ALBERT

Notes: Summary The coronar growth of a cidaroid and an aulodont echinoid are investigated by means of tetracycline labelling. The results are compared with earlier investigations on a stirodont and on a camarodont echinoid in order to evaluate the general features of coronar growth. In all echinoids new coronar plates are added at the apical end of the corona throughout the life cycle. The plates are shifted towards the peristome and they grow peripherically. In cidaroids ambulacral (A-) plates are detached from the firm corona. They are transformed into scales covering the peristomial field. The interambulacral (IA-) plates, however, are partially reabsorbed at the peristomial margin. In this manner the oldest solitary interambulacral plates are lost. The subsequent plates are arranged in pairs. The cidaroids thus show interradial growth even at their peristomial margin. This is unique to echinoids. In non-cidaroids there is a perignathic girdle made up of paired ambulacral auricles with interambulacral ridges in between. In some species the ridge is a solitary element. Therefore interradial growth cannot occur in the peristomial margin. In other species the ridge consists of several elements, but it also grows as a whole. Slight resorption of calcite occurs in places at the peristomial margin. In other places, however, calcite is added onto the peristomial edge. In non-cidaroids, therefore, the widening of the peristome is achieved solely by means of lateral growth in the plates bordering the peristome. The shift of the coronar plates from apicad to orad in noncidaroids is a relative shift only. In all echinoids the coronar plates are arranged in meridional columns. All plates grow up to the peristome. Their growth rates are relatively uniform towards the adambulacral sutures (which run between A- and IA-columns). Their growth rates towards the perradius and the interradius respectively are high in younger plates which are positioned above the ambitus, and decrease rapidly in plates located below the ambitus. Near the peristome the interradiad and perradiad growth rates are always considerably lower than adradiad growth rates. Perradial and interradial growth serve to adjust the plates in size and shape to their respective position in the corona.

Notes: Summary The ultrastructure of the shell gland of Microdalyellia fairchildi (Graff) is described. The gland is composed of two types of secretion cells termed gland cell I and II. The first type consists of two bundles of large flasklike cells placed in opposite positions at the proximal ovovitelloduct. Distinguishing features of these cells are the amply developed rough E.R. with distended cisternae, forming several circular or elongate vesicles, which contain a granular substance, the long cell process with densely packed secretion vacuoles constituting a honeycomblike structure, and autolysosomes. No condensed material is seen in the vacuoles. The process terminates with a narrow channellike part lined by peripheral microtubules and forming septate desmosomal junctions with the epithelial cells of the ovovitelloduct, into which the cells open ventrolaterally. The second cell type is likewise arranged in two lateral clusters at a more distal part of the genital duct. The cells are essentially smaller and the rough E.R. has the usual appearance with flattened cisternae. The secretion bodies are surrounded by a membrane and contain a central core of dense granular material. Some autolysosomes are also present. The fine structure of the endpiece of the process passing through the ventrolateral epithelium of the ovovitelloduct is similar to that of the gland cell I. There are special similarities between the first cell type of Microdalyellia and certain Mehlis gland cells of parasitic flatworms termed S2 cells in Trematoda, indicating that these are homologous. On the other hand there are no such hints concerning the gland cell II and another cell type of the Mehlis gland called the S1 cell.

Notes: Summary The development of abdominal segments in Spirorbis moerchi (Polychaeta: Annelida) was studied by light and electron microscopy. Abdominal segments develop in strict succession from anterior to posterior. Segmentation is initiated in the mesoderm and is followed by segmentation of the ectoderm. The mesoderm of the abdominal segments arises entirely from pygidial residual mesoderm; inward migration of cells from the pygidial ectoderm to give rise to mesoderm does not occur. The primordial germ cells remain distinct from the residual mesoderm of the pygidial growth region. After several abdominal segments have developed, the primordial germ cells “migrate” posteriorly from the achaetous region, invade the abdominal segments, and give rise to the retroperitoneal gonads. Abdominal segment formation is discussed in terms of heteronomy, primordial germ cell origin, gonad formation, and development of the circulatory system.

Notes: Summary The cerebral and epidermal ocelli of the Müller's larva and the cerebral and tentacular eyes of the adult turbellarian Pseudoceros canadensis were studied by electron microscopy. The right cerebral ocellus of the larva consists of one cup-shaped pigmented cell and three sensory cells that bear microvilli. The left cerebral eye of the larva has the above named cells plus a sensory cell with many cilia. Evolutionary significance is attributed to the presence of both ciliary and microvillar photoreceptors in an eye of a flatworm. The one epidermal ocellus of the larva is composed of two cells: a cup-shaped pigmented one bearing flattened cilia, the presumed photoreceptors, and a cell above the cup that adds a few nonciliary lamellae to the stack of ciliary ones from the pigmented cell. The adult eyes contain only microvillar receptors; cilia were not observed.

Notes: Summary 1. The cells of the ventral epithelium form no microvilli but a spongy meshwork of fenestrated ledges and folds which may play a rôle in the adhesion of the animal to the substratum and/or in the extrasomatic predigestion of the food. 2. During cell division typical centrioles occur at the spindle poles. 3. The growing egg cells phagocytize projections of the fiber cells which function as trophocytes. 4. Under the same conditions leading to egg formation so-called S-cells may occur. Some ultrastructural data suggest that they are sperm cells.

Notes: Summary The mesogastropod Pyrazus ebeninus, produces true spermatozoa (here termed euspermatozoa) and multi-flagellate, mobile cells (here termed paraspermatozoa). The mature paraspermatozoon consists of an elongateconical ‘head’ (6.5–8.5 μm in length), constructed of an electron-dense mosaic sheath surrounding a similarly dense, rod-shaped nuclear core (which runs almost the full length of the head). An acrosome-like structure forms the apex of the head. Five to eight axonemes are fixed to the posterior extremity of the nuclear core, each by means of an attachment complex (dense attachment rod, centriolar cap and centriole). A short (3–4 μm) ‘midpiece’ zone follows the head and consists of the multiple axonemes interspersed with very elongate mitochondria. A tuft of short (20 μm) tails (termed minor tails) emerges from the midpiece in addition to one very long tail (termed the major tail) ensheathed in dense granules which resemble glycogen granules. A single membrane surrounds head, midpiece and tails whilst the nuclear core retains the original double nuclear membrane. Developmentally, the multiple axonemes arise from one of a pair of wheel-shaped arrangements of centrioles and attach to posterior indentations in the nucleus prior to its transformation into the nuclear core. Dense vesicles, derived apparently from the endoplasmic reticulum, accumulate along and around the developing nuclear core and (in the presence of microtubules) condense into the mosaic head sheath. Cytoplasmic mitochondria elongate and collect at the posterior axis of the cell, where, together with the axonemes, they form the midpiece. Features not previously reported in other ultrastructural studies of paraspermatozoa include the acrosome-like structure of the head, the structure of the midpiece zone, the glycogen sheath of the major tail, the dense annular structure at the junction of the midpiece and major tail and the presence of microtubules in the final phase of head and midpiece maturation. Some features of the euspermatozoon are also described and the comparative ultrastructure of mature and developing paraspermatozoa and their possible functions in the Gastropoda, are reviewed.

Notes: Summary A previously undescribed receptor in the coxo-trochantinal region of the metathoracic leg of the cockroach Periplaneta americana was found to have central cell bodies. This cockroach stretch receptor is the second sensory receptor in insects reported to possess somata in the CNS and its remarkable similarity to a locust proprioceptor suggests it to be homologous.

Notes: Summary The structural organization of the ocelli of several diplopod species has been studied by means of electron microscopy. The results provide evidence that diplopodan ocelli are derived from typical mandibulate ommatidia, which consequently had been present in diplopod ancestors. The recent representatives of the two sister groups, Pselaphognatha and Chilognatha are characterized by two essentially different types of eye morphology: The eyes of the Pselaphognatha comprise a bilayered rhabdom (built up by 3+4 retinular cells), a few corneagenous cells, a corneal lens, and two vitreous bodies. The latter probably represent relics of a former crystalline cone. On the contrary, the ocelli of the Chilognatha consist of a multilayered rhabdom (built up by a large number of retinular cells), numerous corneagenous cells, and a corneal lens. The dioptric apparatus lacks a crystalline cone. Further structural elements, the distribution of which varies, are the covering cells and processes of hypodermal cells which contain screening pigments. Whereas the eye of the Pselaphognatha can be traced back to a single ommatidium, the ocellus of the Chilognatha can only be interpreted as a merging product of several associated ommatidia or as the result of multiplication and rearrangement of former ommatidial elements. This concept is substantiated by analogous phenomena which occur within other arthropod groups and thus serve as models for the phylogeny of the diplopodan eyes. The comparison of the morphology and the ecology of palaeozoic and recent diplopods demonstrates that the disintegration of former facetted eyes and the modification of ommatidia were induced by the adaptation to cryptic modes of life.

Notes: Summary That the behavior of wood in service results from its “structure” is generally accepted by wood scientists. No doubt this acceptance is due to the broad interpretation of such a term. Structure can refer to the organization of elements on a macro scale, such as in a laminated beam, as well as to the arrangement of cellulose molecules in the crystalline region of an elementary fibril. This presentation focuses on a structural domain that appears increasingly to be a critical one in wood behavior-ultrastructure. The spectrum of terminology that has been used in profusion during the “electron microscopic era” must first be defined so that confusion is minimized. Then a historical evolution of the field of wood ultrastructure can be presented to provide perspective. Structures that have been shown to affect or indeed to control certain processes can be identified. The role of a “non-structure”, the elusive transient capillary, can be illustrated. Microfibrillar organization and cell wall archictecture fall into the realm of ultrastructure as well. The past decade of research in wood science has been productive to a significant extent because of scanning electron microscopy and its accessory tools and techniques. The exploration of wood penetration by wood preservatives, pulping liquors and coatings using this approach has yielded much new evidence. One can speculate about the anticipated contributions of computer-driven SEM, stereology, STEM, and even higher resolution microscopy in the near future.

Notes: Summary Problems associated with handling non-steady liquid flow data are discussed. It is shown that the Darcian flow model is fundamentally imprecise when applied to non-steady state flow in wood due to: 1) the observed decrease in permeability with increased specimen length 2) the wide range of diameters encountered in wood pores. Because of this wide range of pore sizes, liquid penetrates some flow paths more rapidly than others. This may give rise to the occurrence of surface forces resisting penetration, with both “wetting” and “non-wetting” liquids. It seems unlikely that these various factors can be accurately quantified. Hence the precise prediction of liquid penetration rate from steady state permeability data may be illusory.

Notes: Summary To predict the capillary transport of free liquid during the drying of softwood, it is essential to have knowledge of capillary pressure as a function of moisture content. The dependence of the capillary pressure on the wood's moisture content is predicted with a mechanistic model and measured for isothermal moisture movement in the tangetial direction. The experimental measurements confirm the model which is formulated on the postulate that the menisci that form between the liquid and gas in the tracheid lumens control the magnitude of the capillary pressure. Lumen size variation within an annual growh ring was found to significantly affect the local capillary pressure and indicated that separate flow paths are likely to exist in earlywood and latewood.

Notes: Summary A model for the build up of residual growth stresses in cylindrical tree stems is presented. By using Bessel functions the general equations can be solved to allow for surface strain distributions that vary both in the circumferential as well as longitudinal directions. An arbitrary surface strain distribution can be decomposed into Fourier components and the residual internal stresses can be found by superimposing the component solutions due to each new increment of growth. A numerical simulation leading to the residual stress distribution for a typical hardwood is presented.

Notes: Summary Information is presented on the magnitude of errors associated with various sampling simulation schemes of the distribution of three different populations, representing actual bending strength of dimension lumber. Errors were determined between the simulated and actual distributions. Graphical evaluations indicated good fits with the three-parameter form of the weibull distribution for both original and simulated bending strength data, as well as with the resulting error terms. Error terms, based on the simulated versus actual distributions, were generated for the lower 5% exclusion limit, for the 50% exclusion limit and for the entire distribution curve. Simulations were carried out with the aid of Monte Carlo techniques using distribution functions fitted to actual test data for dimension lumber. The errors are expressed as functions of confidence levels. The comparison of the erro obtained through the various sampling schemes could provide some initial directions to choose an economical sampling plan for the presently ongoing in-grade lumber testing program.

Notes: Summary Paintings on 150 wooden panels accepted and not accepted as authentic Rembrandts were investigated using wood-anatomical and dendrochronological techniques. Paintings on 131 panels came from oaks in the coastal area of the Netherlands and 1 panel came from an oak in the interior. The wood of the remaining 18 panels was from beech, poplar and walnut, presumably from the Netherlands, and from cedrela, mahogany and jequitiba imported from Central and South America. In several cases wood of different panels was from the same trunk. By determining the felling date of a tree, a “terminus post quem” could be set for the production of the panel and the completion of the painting, respectively. The art-historical dating of most paintings could be dendrochronologically confirmed. In some cases the attribution was corrected by a few years. In one case an older panel was re-used.

Notes: Summary Structural factors in a Pinus densiflora tree grown under the influence of strong wind were measured. No $$\overline {DP} $$ difference for cellulose molecules was noticed between compression and opposite wood, but the $$\overline {DP} $$ was somewhat lower in the region where the compression wood was concentrated. The degree of crystallinity of cellulose was 45–50% in compression wood, about 50% in normal wood, and 50–60% in opposite wood. The crystallinity decreased with increasing height above the ground. The maximum point of crystallographic b-axis (fiber axis) orientation distribution for cellulose crystallites in compression wood was located at ϕ≅30°, in normal wood at ϕ≅25° and in opposite wood at ϕ≅0°. The cellulose crystallite dimension in the transverse direction was 3.2 nm, corresponding to four cellulose unit cells, a value that was almost constant throughout the wood. In the longitudinal direction, there were large differences in cellulose crystallite dimensions between compression and opposite woods. In compression wood the cellulose crystallite dimensions was 12 nm corresponding to 11–12 cellulose unit cells. In opposite wood it was 17–32.5 nm corresponding to 17–32 cellulose unit cells. These structural factors were apparently affected by the environmental conditions, and the mechanical properties of the wood were influenced by these factors. Opposite wood had longer crystallites, a higher degree of crystallinity and a better orientation distribution of cellulose crystallites in the longitudinal direction. Compression wood, on the other hand, had shorter crystallites, a lower degree of crystallinity and a large angle between the stem and the direction of the crystallites.

Notes: Summary Wood poles have been traditionally tested by “sounding” — striking with a hammer and making a subjective assessment on the basis of the sound emitted. Various other acoustic methods have been developed and employed for this function but none has been accepted on any regular basis as being successful. The propagation of acoustic waves in poles is examined here, and measurements are made using a pulse echo technique of the two acoustic parameters, velocity and damping, on a selection of poles some of which contain decay and rot. The results suggest that measurement of the acoustic damping of longitudinal compression waves may be useful in detecting the presence of decay and rot within a pole.

Notes: Summary The simple pharynges in thirteen species of Turbellaria in the orders Macrostomida, Haplopharyngida, Catenulida, and Acoela have been studied by electron microscopy. After consideration of the functional aspects of the pharynx simplex, the relationship of the pharynx simplex ultrastructure to the phylogeny of the above mentioned groups is analyzed. The Haplopharyngida and Macrostomida are united as a group by the following characters: a pharynx transition zone of 1–5 circles of insunk cells with modified ciliary rootlets or no cilia, pharynx sensory cells without stereocilia collars and with a variable number of cilia, a prominent nerve ring with more than 30 axons circling the pharynx at the level of the beginning of the pharynx proper distal to the gland ring, 2 or more gland cell types in the pharynx, with at least two layers of muscle present and the longitudinal muscles derived from regular and special body wall circular muscles and a prominent post-oral nerve commissure. This specific arrangement can be distinguished from the other pharynx simplex types and is called the pharynx simplex coronatus. The catenulid pharynx simplex is characterized by the lack of a prominent nerve ring, no prominent post-oral commissure, a transition zone with epidermal type ciliary rootlets, recessed monociliated sensory cells, and one or no type of pharynx gland cell. The Acoela are specialized because of the epidermal type rootlets in the pharynx proper. They also lack a transition zone and a prominent nerve ring and have monociliated sensory cells different from the catenulid type. Ultrastructural characters of the pharynx simplex support the view that the Haplopharyngida-Macrostomida are monophyletic. The more primitive catenulid pharynx probably arose from a common ancestral pool with the Haplopharyngida and Macrostomida, although it does not appear possible presently to establish a clear monophyletic line for these forms. The various pharynx types within the Acoela appear to indicate independent origins with no clear link to the basic pharynx simplex type in the three other orders.

Notes: Summary The surface anatomy and the structures lining the pharynx of Halicryptus spinulosus were examined by scanning electron microscopy (SEM). The structures were compared and contrasted with those reported for other priapulids, particularly those features previously studied with SEM. Buccal papillae and pharyngeal teeth of two types were described. Surface structures observed with SEM were: scalids, abdominal setae, anal papillae, posterior warts and ring papillae. The latter three structures are unique among described priapulids. The anal papillae are composed of several rounded, perhaps pedunculate, structures; the posterior warts are composed of mitriform structures in close association with columnar structures. Both are located in separate depressions in the posterior integument. The ring papillae occur on the annuli close to the posterior end. Halicryptus spinulosus was previously thought to lack these structures.

Notes: Summary The ultrastructure of the blood vessels in the caudal region of Branchiostoma is described in specimens injected with indian ink. None of the vessels have endothelial cells delimiting the luminal surface. The vessels are delimited either by dense connective tissue or by the characteristic basement lamella underneath the basal lamina of the myocoelic epithelium. It is proposed that the main blood flow in the caudal region follows different pathways depending on the activity of the animal. During swimming the muscle activity of the caudal muscles may have the effect that more blood flows from the aorta to the myoseptal plexi and is drained to the caudal vessel. In the resting animal it is possible that the blood flow through the myosepta is insignificant, and that the caudal blood flow is more or less restricted to the direct connections between the aorta and the caudal vessel: the dorsoventral anastomosis and the segmental connecting vessels.

Notes: Summary The flagellated chambers of Ephydatia fluviatilis arise at scattered sites within the mesenchyme. Each such site is marked by an accumulation of rounded cells, which appear to be derived from archaeocytes in most respects except that they are smaller than the latter and have no nucleoli in the nucleus. These are choanoblasts, which first develop a flagellum and later a collar; eventually, as choanocytes, they become arranged so as to form a flagellated chamber. Having reached this preliminary stage of completion in the mesenchyme, the flagellated chambers migrate to the endopinacocyte epithelium of the excurrent canal system. Then the choanocytes at the contact point are converted to cone cells. The endopinacocyte epithelium in turn responds by developing one pore cell for each flagellated chamber. The porocytes become permanently joined to the chamber by way of the adjacent cone cells, and from this time on the flagellated chamber is functional.

Notes: Summary Observations on two species of sponges, Tethya seychellensis from the Red Sea, and T. aurantium from the Mediterranean Sea revealed that young colonies are able to detach from their sites of settlement and by means of filamentous podia, to move to other sites in the vicinity. These podia are 10–16 mm long extensions of the sponge body wall that bear an adhesive knob on their distal ends. After being attached, the contracting ‘podia’ pull the spherical colonies of 2.0–3.0 cm in diameter, transporting them to a new site. EM observations showed that in the podia the matrix is rich in contractile myocytes, primary archaeocytes, nucleated archaeocytes and scleroblastic cells, each of which takes part in the moving ability of the podium. It was also shown that some of the archaeocytes go over a process of ripening within the podium and produce collagenic filaments deposited in the internal matrix.

Notes: Summary The position of the oocyte nucleus within the ooplasm is fixed during the mid and late stages of house fly oogenesis. The germinal vesicle is located near the border of the nurse chamber, towards the periphery of the oocyte. The position of the anlage of the chorion raphe is strictly related to the germinal vesicle. As the raphe corresponds to the dorsal side of the later embryo, both the position of the oocyte nucleus and the raphe anlage in the follicular epithelium are early indicators of the dorsoventral axis of the house fly egg cell. In cross sections of the ovary the follicles are arranged in several concentric circles. The dorsal sides of all follicles within the ovary are oriented to an imaginary center. This center of orientation lies eccentrically near the medial part of the female abdomen. The resulting symmetrical pattern can be observed throughout the course of oogenesis. This implies that only a few follicles have the same dorsoventral orientation as the mother fly, and therefore this arrangement is contradictory to the imprinting hypotheses of body axis formation as well as to a possible inductive role of gravity.

Notes: Summary Histological and ultrastructural observations of the digestive tract of eight-armed plutei of Dendraster excentricus are reported. The esophagus is divided into two regions. The uppermost is a narrow tube comprised of ciliated cells that assist in transporting food to the more bulbous lower esophagus where food particles are formed into a bolus prior to entering the stomach. The esophagus is surrounded by a network of smooth muscle fibers that are predominantly oriented circumferentially in the upper esophagus, and longitudinally in the lower esophagus. The musculature of the upper esophagus produces peristaltic contractions, whereas contractions of the muscle of the lower esophagus open the cardiac sphincter and force food from the lower esophagus into the stomach. Axons are associated with the ciliated cells and the muscles of the upper esophagus. The cardiac sphincter consists of a ring of myoepithelium, with cross-striated myofibrils oriented around the bases of the cells. The gastric epithelium is comprised of two cell types. Type I cells, which predominate, absorb and store nutrients, and may be the source of secreted digestive enzymes. Type II cells apparently phagocytize and intracellularly digest whole algal cells. The intestine is comprised of relatively unspecialized cells and probably functions primarily as a conductive tube for the elimination of undigested materials.

Notes: Summary Spermatogenesis was studied at the ultrastructural level in Polydora ligni, P. websteri, P. socialis and Streblospio benedicti. Spermatogonia, spermatocytes, spermatids and mature sperm are described. In all four species, meiosis occurs in the coelom following release of spermatogonia from the gonad. In Polydora spp., chromatin condensation is lamellar with no microtubules present during nuclear elongation. In S. benedicti, chromatin condensation is fibrous with a manchette of microtubules present around the nucleus. In all four species, the acrosome forms from a Golgi-derived vesicle situated at the base of spermatids. The acrosome in Polydora spp. is conical with a distinctive substructure whereas the S. benedicti acrosome is long and spiral. The implantation fossa is short in all species except P. ligni. All four species have elongated sperm heads. The middlepiece as well as the nucleus is elongated in Polydora spp. whereas S. benedicti has a long nucleus but a short middlepiece. Platelet-shaped electron-dense bodies are present throughout the nuclear region and middlepiece of Polydora spp. and the nuclear region of S. benedicti. These membrane-bounded bodies may be energy storage organelles. The use of ultrastructural data in analysis of sibling species complexes is discussed.

Notes: Summary Ototyphlonemertes pallida (Keferstein, 1862) has two statocysts, which are situated just behind the dorsal ganglions on the elongations of the ventral ganglions. Each statocyst consists of one statolith chamber cell, some nerve cells and a number of covering cells and is surrounded by a thick basement membrane. Usually the statolith chamber cell encloses three statolith chambers, which are intercommunicated and surrounded by a double membrane. Each chamber contains a single mobile statolith. Cilia and ciliary structures are lacking. Within the dorsal part of the statocyst some very ramified nerve cells are situated, which form a nerve fibre. In the vicinity of the statolith chamber cell the nerve cells split up into synaptical plates with electric synapses; there are one or several synaptical plates at the level of each chamber. The statolith chamber cell is surrounded by numerous covering cells, which are connected by desmosomes and additionally linked together at the outside in the ventral part of the statocyst. With regard to their structure the covering cells differ greatly from the other cell types, and they do not participate in impulse perception and impulse conduction. There do not exist any closer morphological relations to the statocysts lacking cilia in Coelenterates, Turbellaria, Holothuria, Xenoturbella and Tunicata. The statocyst of O. pallida represents an indigenous structure within the Nemerteans.

Notes: Summary The pericardium in Lepidopleurus asellus (Spengler), Tonicella marmorea (Fabricius), T. rubra L., Ischnochiton albus L., and Calleochiton laevis (Montagu), species taxonomically far apart, is described. It consists of a flat, simple epithelium facing the pericardial cavity, a basement membrane, a muscle layer with two types of muscle fibres, nerve processes, glio-interstitial cells, and fibrocytes, embedded in a loose collagen matrix. The epithelium in L. asellus and I. albus have convoluted lateral cell borders, and in L. asellus very long basal cell processes are seen. Type 1 muscle fibres resemble smooth molluscan muscle. Type 2 muscle fibres resemble cardiac muscle fibres in chitons. Nerve processes associated with glio-interstitial cells and cell processes, run free in the matrix. Synapses in type 1 fibres are covered with glio-interstitial cell processes, lacking in type 2 muscle fibres synapses.

Notes: Summary Dart formation in Helix aspersa has been investigated by SEM of isolated darts at progressive stages in their development, and by histology of dart sacs at the same times. Dart formation begins at the tip of a tubercle where a small group of epithelial cells secrete an organic material filling a small CaCO3 cone that is the first mineralized part of the shaft. Subsequent secretory activity by an increasing area of the tubercle epithelium results in an increase in the diameter and anterior lengthening of the shaft. Continued secretion by the tubercle and dart sac epithelium produces the flare and finally the corona. A pattern of deposition is also evident in the fine structure of the mineral. In the shaft and vanes there is an inner layer of spherulitic prismatic structure which is covered by a layer of irregular patches of simple prismatic structure. The outermost layer of the shaft and vanes has a continuous simple prismatic structure. Two layers are present in the flare, an inner granular amorphous layer and an outer spherulitic prismatic layer. The corona consists of a single rarefied prismatic layer. A mechanism of dart formation is suggested that involves two types of organic matrix, calcifying and non-calcifying. Measurements of the calcium content of darts, dart sacs, and collars indicate that the hemolymph is the probable source of calcium for the dart.

Notes: Summary Primordial gemmules in the freshwater sponge Ephydatia fluviatilis consist of archaeocytes, trophocytes, and spongioblasts. Once the shell has been completed the gemmules contain only archaeocytes filled with food reserves; they become binucleate before completion of the shell. The three layers of the gemmule shell discernible in the light microscope — the inner, vacuolar, and outer layers — are secreted by a highly prismatic spongioblast epithelium along a gradient from the apex to the base of the sponge. All the evidence indicates that these spongioblasts are temporarily modified exopinacocytes. Shell formation is initiated when a group of flat archaeocytes at the periphery of the inner cell complex assumes the function of establishing the shape of the shell. That is, they secrete toward the spongioblast epithelium a boundary layer, detectable only electron microscopically, that marks the inner surface of the shell. Each of the microscleres (amphidisks) in the gemmule shell is formed within an amphidiskoblast in the mesenchyme; when auxiliary cells have contacted the amphidiskoblast, they move together to the spongioblast epithelium in a region of the shell. There the spicule is released from the cell complex and incorporated into the shell. The membrane that closes the pore (micropyle) of the gemmule shell is secreted by a group of modified spongioblasts (micropyle spongioblasts). It consists of a continuation of the inner boundary layer lining the shell itself, detectable only electron microscopically, plus two other layers not identical with any layer of the shell. Toward the end of shell formation the spongioblasts flatten, creating a permanent pavement epithelium that secretes a thin envelope of spongin over the surface of the completed gemmule.

Notes: Summary Orifice flow and drag theory are found theoretically to be generally inapplicable to axial gas flow through conifer wood under the conditions normally used for gas permeability studies of the material. However, orifice flow theory might be applicable at higher mean pressures or at higher applied pressure drops. Methods of testing this possibility experimentally are discussed.

Notes: Summary The maximum torsional-shear stress of 5 softwoods and 4 hardwoods were tested in the radial and tangential planes. These tests were carried out in glycerin which was preheated to different temperatures between 22°C and 150°C, inclusively. The dense hardwoods possess 2.4 times higher shear stress than softwoods at 22°C. However, at elevated temperatures, the same degree of shear stress reduction (77 %) is obtained for hardwoods and softwoods in both radial and tangential failure. Thus, the reduction in shear stress is independent of physical and structural wood variables.

Notes: Summary Past research on the combustion and pyrolysis of wood have often indicated a link between wood microstructure and its observed properties in fire exposure. The present research, after utilizing an instrumented fire exposure shown to simulate actual fire conditions, examines the microstructure of fire damaged wood and considers the implications of microstructural changes seen on the burning process. Differences in microstructural detail between wood and char, as well as fissure geometry, were shown to be consistent. The demarcation between damaged and undamaged wood was shown to be extremely small (several cell layers in thickness). The resulting microstructural observations are considered in light of published kinetic data on wood combustion and current theories and data on thermal degradation of wood.

Notes: Summary Radial pattern of variation in the first-formed earlywood tracheid length in blue pine shows that it increases outwards from the pith at first rapidly up to the 10th ring, then more slowly up to about the 40th ring and thereafter it remains more or less constant. It is correlated significantly and positively with both age and distance from the pith up to 40 years. In the mature wood zone i.e. after 40 years, tracheid length is not affected by either age or distance from the pith. The mean tracheid length of mature wood is significantly and positively correlated with the mean tracheid length of juvenile wood and also with the tracheid length of each of the juvenile wood rings. Based on the results of this study some guidelines for sampling are proposed. Trees with greater than 51 cm d.b.h. or above 40 years of age can be compared by sampling only four outermost consecutive mature wood annual rings; and those with less than 51 cm d.b.h. or below 40 years of age can be compared by sampling any of the juvenile wood rings.

Notes: Summary Crosslinking of wood with gaseous formaldehyde improves its hygroscopic and dimensional behaviour and its resistance against microorganisms. However, this formaldehyde crosslinking reaction takes place only in the presence of an acid catalyst, which results in losses in mechanical strength. Electron microscopic analysis of poplar samples treated under various conditions of reaction revealed severe degradation of cell wall substances. The formaldehyde gaseous nonomer is shown to have some hydrolytic action on cellular structure. Sulphur dioxide and particularly hydrochloric acid used as catalysts caused substantial extraction of matrix substances from fibre walls. Walls of vessels and ray parenchyma cells seemed to become less degraded. Strong exposure of cellulose fibrils during formaldehyde crosslinking reactions, illustrated by highly electron transparent zones in the S1 and inner S2 layers, occurred for both the SO2 and HCl catalyzed treatments. In general a more extensive degradation was observed for the formaldehyde-hydrochloric acid reaction and for the formaldehyde sulfur dioxide treatments using a high acid concentration. From these observations it might be concluded that the reduced mechanical strength of formaldehyde-treated woods are partially based on the hydrolysis of the carbohydrate backbone of the cell wall.

Notes: Summary The structure of the non-cyclic benzyl aryl (α-0-4) ethers 4 and 5, proposed by Freudenberg and Friedmann (1960) and recently boubted by Leary (1980), is discussed on the basis of previously published experimental results. Further evidence in favor of the occurrence of non-cyclic α-0-4 bonds in lignin is provided. A critical comment is, however, given on the formation of non-cyclic α-0-γ bonds in lignin according to Leary (1980).

Notes: Summary Light and dark adaptations were studied in the eye of Squilla mantis. Light adaptation is characterized by (1) a proximal shift of the distal pigment sheath (DPS) surrounding the proximal portion of the crystalline cone above its zone of contact with the rhabdom; (2) flattening of the distal pigment sheath; (3) lengthening of the crystalline cone correlated with shortening of the rhabdom; (4) a migration of screening pigment granules in retinula cells in the protoplasmic bridges crossing the perirhabdomal space. In animals kept in constant darkness, longitudinal displacements of the distal pigment sheath were found to be subject to a circadian rhythm characterized by a maximal light adaptation state at about 5 p.m. and a minimal one at 5 a.m. Screening pigment granule translocation in retinula cells does not show such rhythmic activity.

Notes: Summary The male copulatory apparatus of Pelodera strongyloides is described using electron microscopical pictures. The genital structures are composed of a spicule, a spicule sac and a bursa copulatrix. Papillae of the bursa copulatrix, which are chemoreceptors, and papillae of the spicule sac and the spicule, which are mechanoreceptors, represent the sensory equipment. The co-operation of all structures during copulation is discussed.

Notes: Summary The morphology and mechanics of the larynx and the ventral pharyngeal valves of the pigeon (Columba livia L.) are described. The glottal apparatus is an elastic ring of cartilage since the caudomedial ridges of the cricoid wings are tightly interconnected via the median cauda procricoidea. The bilateral arytaenoids can only hinge mediolaterad relative to the corpus procricoideus as a result of their particularly shaped articulation facets. The procricoid is tilted by changing the constriction of the ring. At rest, the glottis is held in an intermediate open position because the arytaenoids are kept along the dorsal ridges of the alae cricoideae in an ‘elastic open rest’ position by the elasticity of the ring and of the lig. arytaenocricoideum. The large dilator muscle covers the apparatus as a continuous sheet. The constrictor muscle complex, however, has five discrete sections, each having a different origin. They all insert on the heavy interarytaenoid ligament and one of them is a sphincter. These five sections can constrict the cricoprocricoid ring, thus causing a forward tilting of the procricoid which forces the arytaenoids to hinge mediad. The glottal apparatus operates as a drill-chuck system in which the arytaenoids are taken as the graspers (chuck jaws). The model is studied by a movement- and electromyographic analysis of three common glottal actions: respiration, reaction to water, and reaction to touch. The ‘elastic open rest’ position of the glottis is found in anaesthetized birds. The drill-chuck model is tested by the comparison of the recorded myogram pattern with the myogram pattern that must follow from the model for the moving structures. The ventral pharyngeal valves are erected by the long submucosal m. hyovalvularis, running between the basihyal and the dorsal side of the gland. cricoarytaenoidea in the valves. The valves are pulled down to the floor of the pharynx by a network of collagen and elastic fibres connected to the small m. tracheovalvularis, which runs down to a medium strand attached to the first tracheal ring. These two subsystems of the floor of the pharynx operate independently during respiration. But, in case of pecking and drinking they show combined actions which place them as parts of a highly integrated system.

Notes: Summary The entire gut of Cyathura carinata is lined by a cuticle indicating its completely ectodermal origin. By flattening of the epithelial folds and possibly also of reserve-folds of the plasma membrane the intestine is highly dilatable, an adaptation towards a rapid uptake of the food which is sucked in by means of specialized mouthparts, which pierce the body wall of its main prey, the polychaete Nereis diversicolor. Bundles of microtubules within the intestinal cells presumably represent cytoskeletal structures providing protection against mechanical stress. Spirally arranged muscle fibres, which form peculiar contact areas with the gut, can easily follow any dilatation. A few indications of the metabolic functions of the anterior gut epithelium have been found: Basally and apically located labyrinthine structures of the plasma membrane, apically located clear vesicles, positive reactions for lysosomal, mitochondrial and membraneous enzymes, a strikingly thin and loosely arranged cuticle through which food substances of low molecular weight may diffuse. The cells of the gut and also of the digestive caeca are interconnected by desmosomes, extensive pleated septate junctions, and gap junctions. In the pleon the gut is less dilatable and devoid of plasma membrane specializations. In this area tendon cells, particularly rich in microtubules, serve as attachment sites for the dilating muscles of the rectum. The digestive caeca synthetize and secrete digestive enzymes, mix food and enzymes in their lumen, resorb food molecules, store lipids and glycogen. In the glandular epithelium small cells, rich in rough ER, and a majority of large cells, rich in lipid droplets, occur which, however, are interconnected by a series of morphologically intermediate cells. All cells bear an apical brush border, form a basal labyrinth and contain high to medium activities of acid phosphatase, nonspecific esterases, ATPase, and succinic dehydrogenase. The ER-rich cells are far less frequent than in the omnivorous or herbivorous isopods (Sphaeroma, Idothea, Asellidae, Oniscoidea).

Notes: Summary About 1 s after appropriate stimulation, arms of Florometra serratissima break at articulations called syzygies that are specialized for autotomy. The fine structure of unreacted and of newly broken syzygies is described. The unreacted syzygy includes (1) ligament fibers consisting of collagen fibrils interconnected by interfibrillar strands and (2) axons filled with presumed neurosecretory granules. The newly broken syzygy includes (1) ruptured ligament fibers consisting of swollen collagen fibrils associated with interfibrillar globules and (2) axons containing few presumed neurosecretory granules, some of which are fixed in the act of exocytosis; moreover, the calcareous skeleton adjacent to the broken syzygy is partly eroded. The observations before and after breaking suggest that the autotomy mechanism may comprise the following sequence of events: rapid neural transmission from stimulation site to syzygy triggers a massive exocytosis of granules from presumed neurosecretory axons; the released neurosecretions (which could include chelating agents, strong acids, proteolytic enzymes or enzyme activators) etch the skeleton and lower the tensile strength of the ligament fibers by weakening the collagen fibrils and/or the interfibrillar material; breakage of the ligament fibers, the major connective tissue of the articulation, is quickly followed by rupture of all the other tissues at the syzygy.

Notes: Abstract A new method is described for the determination of phytoplankton growth rates and carbon biomass. This procedure is easy to apply and utilizes the labeling of chlorophyll a (chl a) with 14C. Pure chl a is isolated using two-way thin-layer chromatography, and the specific activity of chl a carbon is determined. Data from laboratory cultures indicate that the specific activity of chl a carbon becomes nearly equal to that of total phytoplankton carbon in incubations lasting 6 to 12 h and can be used to calculate phytoplankton growth rates and carbon biomass. Application of the method to the phytoplankton community in an eutrophic estuary in Hawaii indicates that the cells are growing with a doubling time of about 2 d and that about 85% of the particulate carbon consists of phytoplankton carbon.

Notes: Abstract A non-thecate dinoflagellate, Gymnodinium splendens, was studied in a 12 d laboratory experiment in 2.0x0.25 m containers in which light, temperature, and nutrients could be manipulated. Under a 12 h light: 12 h dark cycle, the dinoflagellates exhibited diurnal vertical migrations, swimming downward before the dark period began and upward before the end of the dark period. This vertical migration probably involved geotaxis and a diel rhythm, as well as light-mediated behavior. The vertical distribution of nitrate affected the behavior and physiology of the dinoflagellate. When nitrate was present throughout the container, the organisms resembled those in exponential batch culture both in C:N ratios and photosynthetic capacity (Pmax); moreover, they migrated to the surface during the day. In contrast, when nitrate was depleted, C:N ratios increased, Pmax decreased, and the organisms formed a subsurface layer at a depth corresponding to the light level at which photosynthesis saturated. When nitrate was present only at the bottom of the tank, C:N ratios of the population decreased until similar to those of nutrient-saturated cells and Pmax increased; however, the dinoflagellates behaved the same as nutrient-depleted cells, forming a subsurface layer during the light period. Field measurements revealed a migratory subsurface chlorophyll maximum layer dominated by G. splendens. It was just above the nitracline during the day, and in the nitracline during the night, which concurs with our laboratory observations.

Notes: Abstract The adenylate energy charge ratio (EC) of 8 species of zooplankton ranged from 0.70 to 0.89. Eucalanus subcrassus had significantly (P〈0.05) lower EC when captured during a 30-min tow than during a 3-min tow, indicating stress at capture. The concentration of ATP in the 8 species ranged from 9.1 to 36.0 μg/mg protein and from 0.17 to 15.7 μg/mg dry weight. Excluding a low value for the ctenophore Pleurobrachia sp., the average concentration was 8.1 μg ATP/mg dry weight, which is equivalent to an approximate C/ATP ratio of 50.

Notes: Abstract Uptake of radioactively labeled glycolic acid, arginine, glutamic acid, and glycine by natural marine bacterial population was rapid and approached a maximum value which was over 90% of the total substrate. Uptake of glucose was rapid, but had a maximum uptake of less than 80%. All substrates except glycolic acid were assimilated to a similar degree (a maximum of more than 30% of the total given substrate). Glycolic acid had a maximum assimilation of less than 10%. The presence of glycolic acid resulted in no extracellular metabolites detectable on a gel permeation column. Between 5 and 10% of the other substrates were transformed and excreted within 72 h by the bacteria. These exudates were both nominally larger and smaller than the given substrates.

Notes: Abstract A blue carotenoprotein, extracted from the marine spongia Suberites domuncula has been purified. The apoprotein has a molecular weight of about 31,000; the chromophore is not astaxanthin but it is similar to a monohydroxy, mono-expoxycarotene. The amino acid composition of the protein is briefly discussed.

Notes: Abstract The juveniles, non-gravid females, gravid females and males of the free-living marine nematode Anoplostoma viviparum Bastian showed markedly different distributions within layers of mud from Southampton Water sampled during the early spring of 1975. Of the total population, 92% of gravid females occurred in the anoxic layer, 73% of juveniles occurred in the flocculant layer, non-gravid females and males were found in approximately equal numbers in both the flocculant and oxidised layers but none in the anoxic layer. A tentative activity cycle based on these distributions is put forward for consideration, taking into account the water movement within the estuary.

Notes: Abstract We determined concentrations of dissolved adenosine triphosphate (DATP) and rates of its uptake by marine bacteria in seawater from the continental shelf and Gulf Stream off the southeastern USA. Dissolved adenosine triphosphate (DATP) concentrations (22 to 568 ng l−1) were highest in nearshore surface waters and at the interfaces of continental shelf water and upwelled water from the cold wall of the Gulf Stream; lowest concentrations were found in surface water furthest from shore and in subsurface waters. Bacterial population density and DATP uptake velocities were determined to calculate average rates of DATP uptake per-cell. In general, percell rates of uptake were highest in samples having the highest in situ concentrations of DATP and varied markedly with small-scale temporal and spatial changes. Per-cell uptake by attached bacteria was one to two orders of magnitude faster than uptake by free-living bacteria; this difference could be accounted for by the much larger average cell volume of the former.

Notes: Abstract Light profiles beneath the tabular coral species Acropora cytherea and A. hyacinthus were examined at Rib and Broadhurst Reefs, central Great Barrier Reef, in November 1980. They show a strongly decreasing illumination gradient towards the central stem. Beneath tables at 10m deep, which receive about 7.0 mW cm−2 at solar noon, substrate irradiance falls to a minimum of about 5% ambient or to about 0.4 mW cm−2. Thus, from previously reported compensation values, most sub-table substrate may receive above-compensation irradiance. Illumination beneath tables screened by foil is significantly lower. The coral communities beneath tables of these two species plus those of A. subulata and A. clathrata support an average 26 colonies m−2, at a cover of 40%, nearly identical to adjacent, unshaded quadrats. Species richness is likewise very similar. Species richness and colony density beneath the tables increase inwards from the perimeter of the shaded areas, decreasing only near the central stems. Dark adaptation and reduced competitive and grazing pressure are suggested explanations for the latter. It is concluded that shading does not provide a significant competitive advantage for Acropora spp. tables at 10 m deep.

Notes: Abstract Seasonal changes in ambient NO 3 − and NH 4 + , tissue composition (N, C, and C/N ratio), and frond growth rates for Macrocystis pyrifera (L.) Agardh were examined. Ambient NO 3 − showed distinct seasonal variations. Frond growth rates were variable, but showed no clear correlation to ambient NO 3 − . The average N content of plant tissue did, however, show the same seasonal variations as ambient NO 3 − . The longitudinal distribution of total tissue N and various components of tissue N along fronds were also analyzed. Several distinct patterns were found: high levels of protein N at growing tips and elevated levels of soluble N in lower parts of the frond. Free amino acids accounted for a major portion of the soluble N, but neither NO 3 − nor NH 4 + accumulated in the plant tissue. The longitudinal distribution of N along the fronds is compared to reported variations in C metabolism, and it is concluded that C and N sourcesink relations do not always coincide and bidirectional translocation may occur.

Notes: Abstract The intertidal limpet Siphonaria kurracheensis (Reeve, 1856) has a bimodal vertical distribution of abundance on rocky shores at Rottnest Island, Western Australia. An electrophoretic study of 5 polymorphic enzymes revealed no consistent genetic differences between adults high and low on the shore. Contrasting with this absence of a detectable genetic response to the steep environmental gradients in the intertidal zone, there were genetic differences among low-shore adults from different sites, and between adults and recruits. This genetic differentiation could be due to either localized selection or temporal variation in the genetic makeup of recruits.

Notes: Abstract Deep-burrowing crustaceans are common on all coasts. In a series of model experiments conducted at the Hawaii Institute of Marine Biology from March to October 1977, the effect of the alpheid shrimp Alpheus mackayi Banner and Banner, on material fluxes across the sediment-water interface has been determined. Viewed as a “biological pump”, the shrimp's irrigation pattern was not random, but intermittent, with a mean period of 6 min activity and 16 min resting. Plume velocities between 1 and 18 cm s−1 were measured by seawater-resistant hot-wire anernometry at the apertures of active burrows. Based on 55 h of velocity data, mean hourly pumping rates of 0.35 liters h−1 were calculated, with an average mechanical energy of 4000 erg h−1 dissipated by burrow-wall friction and plume mixing. In microcosm experiments with 177 cm2 sediment surface area and 120 cm2 burrow-system surface, the pumping of one shrimp enhanced the release of silica from the pore water by an average factor of 5 compared to concentration gradient-driven flux across the sedimentwater interface in a control core with the same dimensions but without a shrimp. Our data suggest that “real-world models” of interfacial fluxes without inclusion of the macro-infauna as biological pumps will be unrealistic.

Notes: Abstract The anemone Phymactis clematis exhibits intraspecific agression. An investigation into dominance relationships amongst the 3 colour morphs collected from Vĩna del Mar, Chile, during June, 1980, revealed them to be equally aggressive. The outcomes of experimental contests appeared to reside solely with size-dependent differences in the threshold for the release of agression. Contests were asymmetric and larger individuals displayed aggression earlier against smaller opponents, and won encounters. An analysis of times for the onset of aggression in contests showed that they were highly variable and were not a good indicator of the absolute aggressive ability of individuals as denoted by dominance rankings. It provided, however, evidence indicating a lack of assessment of opponent size during initial contact. This is discussed in relation to the evolution of aggression in anemones and to the concept of evolutionarily stable strategies in contest behaviour. It is concluded that future work on the apparent size-dependent threshold will most instructively be conducted at the neurophysiological level.

Notes: Abstract Growth of individually marked specimens of Notoacmea scutum (Rathke) was followed for 15 months (April, 1978 to June, 1979) at a field site in central California, USA. Growth rates were highly seasonal, being highest from late spring through early summer and lowest during winter. Growth rate also varied significantly with intertidal height: limpets lower in the intertidal zone grew faster. Both relationships may have been related to the relative abundance of food or to the amount of time available for foraging. Recently settled limpets, which were present throughout the year, grew to approximately 17 mm in length by the end of their first year; by then, they had also reached the size at which mature gonads were consistently found (16 mm). Limpets were almost 26 mm long by the end of the second year. Substantial mortality occurred throughout the year, but it was particularly severe during winter, when a large portion of the reproductive population was lost. This pronounced winter mortality was probably not caused by invertebrate predators such as seastars. Most limpets at the study site were less than 2 yr old.

Notes: Abstract In vivo chlorophyll fluorescence is particularly interesting ot ecologists because of various concepts (biomass, productivity, physiological state) associated with it. Using a modified spectrophotofluorometer, we have studied the kinetics of fluorescence in unialgal cultures and in a natural population of marine phytoplankton. Our apparatus did not achieve satisfactory results with cell suspensions having a chlorophyll concentration less than 10 μg l-1. We have also tested a method for estimating kinetics of diluted cultures and marine phytoplankton using cells collected on glass-fibre filters. For unialgal cultures in the exponential growth phase, the method proved satisfactory, and results obtained from both cell suspensions and filters were in good agreement. However, for aged cultures (principally diatoms) and natural marine phytoplankton the method proved unsuitable. The kinetics of fluorescence induction vary according to taxonomic position of the cells, light intensity of the measuring excitation beam and productiveness of the culture medium. The importance of the kinetics of fluorescence induction for characterization of phytoplankton activity is discussed.

Notes: Abstract Spatial and temporal patterns of gene-enzyme variation were estimated in the sibling species Gammarus zaddachi Sexton and G. salinus Spooner by starch gel electrophoresis. Twenty-one G. zaddachi and 18 G. salinus populations from coastal and estuarine areas in the Baltic Sea, North Sea and other localities of north-western Europe were surveyed. Both amphipods display similar electrophoresis patterns of the enzyme systems studied. Considerable interspecific and interpopulational differences were detected in allele frequencies at three highly polymorphic loci, phosphoglucose isomerase (PGI), glutamate oxalacetate transaminase (GOT) and arginine phosphokinase (APK). G. zaddachi exhibits a pronounced genetic heterogeneity in most areas of the sampled range. Populations from northern French and western English coasts differ significantly from the other samples in allele frequencies at the PGI or APK locus, respectively. Baltic populations are widely uniform in their genetic composition but can be distinguished from samples taken at North Sea sites in allele frequencies at the APK locus. The latter reveal a clinal variation, ranging from the Danish to the French coast. In contrast to G. zaddachi, a low degree of genetic differentiation was observed among the G. salinus populations examined. This indicates that migration and interregional mixing may be more important in maintaining the genetic structure than in G. zaddachi which, compared to G. salinus, prefers habitats of lower salinity levels. Evidently, less extensive dispersal capabilities owing to the confinement of G. zaddachi to brackish waters of dilute salt concentrations may account for a diminished gene flow and considerable genetic separation of local populations. This assumption is supported by the genetic homogeneity documented in Baltic G. zaddachi populations. In view of the low and constant salinities in wide areas of this brackish-water sea such barriers do not exist. Survey studies performed with selected populations over a 3-yr period demonstrated a general pattern of temporal constancy in the allozyme variation observed.

Notes: Abstract Pachygrapsus crassipes Randall and Hemigrapsus oregonensis (Dana), coexisting grapsid crabs, were studied in a tidal marsh near Santa Barbara, California, USA. Both species are found in intertidal mud burrows along banks of the slough channels. H. oregonensis occupies the entire intertidal vertical range on the mud banks, whereas P. crassipes inhabits primarily the uppermost zone (above +1.4 m). In areas where both species occur in large numbers, the density of H. oregonensis in the uppermost zone is less than in areas with only a few P. crassipes. P. crassipes does not excavate burrows, but moves into and enlarges the existing burrows of H. oregonensis. P. crassipes also preys upon H. oregonensis, but burrowing provides the latter with partial refuge from predation. Population structures of the two species differ in the number of small crabs that occur in different areas of the slough. Few small specimens of P. crassipes are found along the upstream muddy banks of the slough, whereas young specimens of H. oregonensis are abundant in these areas. Physical factors such as salinity and siltation may restrict settlement or reduce survivorship of small P. crassipes. A balance between the predatory/competitive abilities of P. crassipes and the greater tolerance of H. oregonensis to physical stresses is proposed as a mechanism of coexistence.

Notes: Abstract Experiments were designed to determine whether anemotaxis shown by the terrestrial hermit crab Coenobita rugosus H. Milne Edwards is (i) an orientational strategy leading the crabs to sea or (ii) a strategy improving rectilinear flight. In an arena with uniform landscape, hermit crabs from different beaches of the Aldabra atoll orientated during daylight in the direction of the sea of their own beach; this orientation was only slightly affected by wind direction. Under artificial wind conditions, at night, all hermit crabs displayed positive anemotaxis, independent of the orientation of the home beach, thus leaving little support for the first hypothesis. During the day, with the sea and beach both visible, all the hermit crabs on the beach moved landwards irrespective of wind and home beach direction.

Notes: Abstract Color patterns of the shallow-water shrimps Heptacarpus pictus and H. paludicola are formed by chromatosomes (usually termed chromatophores) located beneath the translucent exoskeleton. Development of color patterns is related to size (age) and sex. The color expressed is determined by the chromatosome pigment dispersion, arrangement, and density. In populations with well-developed coloration (H. pictus from Cayucos, California, 1976–1978, H. paludicola from Argyle Channel, San Juan Island, Washington, June–July, 1978), prominent coloration was a characteristic of maturing females, breeding females, and some of the larger males. In the Morro Bay, California, population of H. paludicola (sampled 1976–1978), color patterns were poorly developed except in a few large females. In both species, most shrimp lose color at night because of pigment retraction in certain chromatosomes. In both species, there are 5 basic morphs: 1 transparent and 4 colored morphs. In the colored morphs, the color patterns are composed of bands, stripes, and spots which appear to disrupt the body outline. Each color morph also has a common environmental color in its color pattern, e.g the green of green algae, the whites and pinks of dead and living coralline algae, and various shades of tidepool litter. These shrimps are apparently under heavy predation pressure by fish, and it is suggested that the color patterns are camouflage against such visually-hunting predators.

Notes: Abstract Re-examination of ine structure of postlarvae previously identified as the abyssal species Ophiura ljungmani (Lyman) in a time series of samples taken from 1975 to 1980 from a 2900 m deep permanent station in the southern Rockall Trough (Northeast Atlantic Ocean) has shown the majority of the large summertime peak of brittle-star postlarvae to belong to a second species. Most were incomplete and probably corpses when collected. The few intact specimens present were identical to postlarvae collected in benthic samples from the neighbouring continental slope, where a dense population of the bathyal species Ophiocten gracilis (G. O. Sars) is present from 600 to 1 200 m depth. Examination of population size-structures indicates synchronous reproduction in January/February and annual recruitment to the population. The presence both of “Ophiopluteus ramosus” and intact postlarvae of Ophiocten gracilis in midwater plankton samples from the vicinity of the permanent station in March/April are thought to derive either from the adjacent slope population or, less probably, from larvae transported in the North Atlantic Current from the Flemish Cap area off Newfoundland. In deep water, viability of these benthic postlarvae is low, none surviving longer than the following winter in the Rockall Trough. These observations suggest a large seasonal transfer from the slope of non-viable larvae and postlarvae as food to the abyssal benthic community.

Notes: Abstract Samples were taken from a 2 900 m deep permanent station (centred on 54°40′N; 12°16′W) in the southern Rockall Trough, from November 1975 to September 1980, inclusive. Revision of juvenile size frequencies was necessary after removal of postlarvae of an annual non-viable settlement of Ophiocten gracilis (G. O. Sars) that were mistakenly included in a previous analysis. The present study of the revised data shows that settlement of Ophiura ljungmani (Lyman) occurs in summer when disk-size frequencies are dominated by the newly metamorphosed postlarvae. The likely age composition in larger sizes was suggested from the progression of modes along the size axis in juvenile size classes in consecutive were developed from Gaussian mixtures fitted by constrained computer search using, as starting values, component parameter values suggested from the frequency histograms. Choice between competing solutions was made on the basis both of goodness-of-fit and biological plausibility. However, identification of year-class structure amongst sizes 〉3 to 4 mm disk diameter remained conjectural owing to the low frequencies of adults in the samples. Comparison of the fitted component-means in the time series suggested a marked seasonal growth pattern, with maximal growth in spring. Probable age composition amongst adult sizes was extrapolated from von Bertalanffy growth parameters estimated from the means of juvenile year classes.

Notes: Abstract A one year study was carried out to investigate the variations in benthic community structure along an environmental gradient of salinity and bottom substratum in a sub-tropical estuary in Hong Kong. The community was dominated by the gastropod Turritella terebra, and to a lesser extent, by the gastropod Murex trapa and the crab Portunus hastatoides. The total number of animals, biomass as well as the domanance of T. terebra in the community decreased, while species diversity increased along a gradient of increasing salinity and decreasing siltclay fraction of the sediment.

Notes: Abstract We have studied the interaction of extra- and intracellular osmoregulatory mechanisms which the estuarine bivalve Rangia cuneata utilize to tolerate salinities ranging from freshwater to 25 ppt. The normally occurring intracellular free amino acid (FAA) accumulation in hyperosmotically stressed R. cuneata isolated ventricles was significantly reduced in the presence of divalent cation concentrations lower than that normally found in the blood. The effect of the divalent cations was not on the intracellular biosynthetic pathways responsible for FAA synthesis but rather on the myocardial membrane permeability to FAA. These data indicate that the effectiveness of the intracellular FAA mediated volume regulatory response in R. cuneata is dependent on both intracellular FAA accumulation and on the extracellular regulation of blood divalent cation concentration. This dependency indicates one interaction of extra- and intracellular osmoregulation in R. cuneata.

Notes: Abstract Rates of oxygen and carbon-dioxide exhange were measured in symbiotic and aposymbiotic specimens of the sea anemone Anthopleura elegantissima while fed and starved under light or dark conditions. Respiratory quotients indicated that fed anemones switched from a carbohydrate to a fat catabolism when starved, with the exception that symbiotic individuals starved in the light showed a pronounced carbohydrate catabolism for over 1 month. The source of the carbohydrate was probably photosynthate translocated by the dinoflagellate Symbiodinium (=Gymnodinium) microadriaticum (Freudenthal) living in the anemones' tissues. The starved symbiotic anemones maintained in the light had lipid levels not significantly different from fed controls and 44 to 61% higher than starved aposymbiotic anemones after 1 month. Thus, the quality and quantity of the metabolic flux from the symbionts to the sea anemone were sufficient to conserve the host's lipid reserves.

Notes: Abstract Changes in the rates of utilization of dissolved compounds during the period of visceral mass regeneration were examined in the crinoid Cenometra bella (Hartlaub). Rates of respiraton and incorporation of labelled amino acids increase, reaching a maximum 2 d after evisceration and returning to normal after 14 d. Rates of incorporation of radioisotope into the organic components of the arms and cirri decrease, while incorporation rate into the visceral mass increases. Incorporation rates of amino acid-derived radioactivity into skeletal carbonate and the ash-free dry weight:protein ratio of arms, cirri and oral disc decrease, reaching a minimum 2 d following evisceration.

Notes: Abstract Based on direct monitoring of feeding and growth under field conditions and frequent measurements of respiration and energy content in the laboratory, annual energy budgets were derived for Polinices duplicatus feeding on Mya arenaria at Barnstable Harbor, Massachusetts. The gross growth efficiency (Pg/C) of P. duplicatus was high (35%) and varied inversely with snail size. The proportion of ingested energy expended on respiration (R/C) was modest (44%) and varied directly with snail size and inversely with temperature. The energetic efficiencies of P. duplicatus agreed with the few results available for othe predatory molluscs and differed from most results available for herbivorous and detritivorous molluscs.

Notes: Abstract Among the Hawaiian species in the genus Conus, larval life histories range from long-term planktotrophy to nonpelagic lecithotrophy. Prehatching developmental time, hatching size, pelagic period and total prejuvenile developmental time are all significantly correlated with egg size, while settling size is correlated with none of these larval characteristics. Therefore, larval life history patterns in the genus Conus appear to be determined by 2 sets of selective forces: the first influencing egg size, and the second stipulating settling size. As egg sizes become larger, hatching sizes and prehatching developmental time increase while pelagic periods and total prejuvenile developmental times decrease. Settling size appears to be related to water depth, but food requirements of newly metamorphosed juveniles may also be important.

Notes: Abstract Growth of Mytilus edulis L. was measured in aquaria with through-flowing sea water at different levels of constant algal concentrations. The amount of food and oxygen consumed by the mussels were measured over given periods as well as the changes in dry organic weight during the same periods. From these parameters it was possible to make simple energy budgets and to compare the estimated growth with actual growth, and, further, to determine growth efficiences at different food levels. Energy budgets were made for mussels grown at algal concentrations of 0, 1.6×103, 3.0×103 and 26.0×103 Phaeodactylum tricornutum cells x ml-1. The estimated growth was found to be close to actual growth at algal concentrations above maintenance level and the net growth efficiency was found to be between 18% (3.0×103 cells x ml-1) and 61% (26×103 cells x ml-1). It has been shown that the filtration rate is independent of algal concentrations between about 1.5×103 to 30×103 P. tricornutum cells x ml-1. Outside this range a decrease in filtration rate was noticed.

Notes: Abstract The relationships between aggressive behaviour and animal density and between aggressive behaviour and metabolic excretion have been investigated in Carcinus mediterraneus Czerniavsky. Increasing the crab density by increasing the number of crabs or reducing the available area revealed that the aggressive interactions perindividual did not increase. The frequency of interactions reached a maximum in several minutes following the introduction of crabs. Individuals isolated between 6 and 24 h were more aggressive than non-isolated ones. The water in which a group of crabs had been held had an inhibitory effect (not abolished by commercial aquarium filters) on aggressiveness of pairs of crabs grater than plain water or water in which single crabs had been kept. No ‘home-group’ effect was observed. The effect of ‘group’ water was enhanced by increasing the concentration of crabs in the duration of confinement, and it is probably due to the accumulation of catabolites in the medium. Crabs kept in groups had a greater excretion than isolated crabs and the nitrogen oupput decreased with an increase in the number of crabs or whith a decrease in the size of the tank (with a constant volume of water and number of crabs).

Notes: Abstract Feeding patterns during four 24-h periods, sampled at 3-h intervals, were investigated for the mummichog Fundulus heteroclitus, in a Delaware, USA tidal marsh. Two factors potentially influencing feeding patterns, time of day and tide height, were examined. On 2 of the sampling periods a low tide occurred in the morning, while on the other 2 sampling periods a high tide occurred in the morning. Results are reported as g-dry wt. of food per g-dry wt. of fish. F. heteroclitus is primarily a daytime feeder that most actively feeds at high tide, regardless of whether or not the high tide inundates marsh surface areas. When tide height was sufficient to inundate the marsh surface, fish invaded these areas and consumed prey characteristic of the marsh surface. F. heteroclitus is an important link in energy transfers between the marsh surface and subtidal systems, enhancing its own energy supplies by consuming marsh surface prey whenever available.

Notes: Abstract Crude extracts from various regions of the digestive tract of pond grown milkfish were tested forttheir ability to catalyze the hydrolysis of various carbohydrates. The most active carbohydrases were those involved in the hydrolysis of α-glucosidic bonds. Maltose, trehalose, dextrin, starch and glycogen were rapidly hydrolyzed in the presence of crude extracts from the intestines and the pyloric caeca. High amylase activity was observed in extracts from the intestines, pancreas, pyloric caeca and liver. The intestinal amylase had optimum activity at pH 6.2 and at a temperature of about 50°C. It was active at a chloride concentration of 10 to 40 ppt. The amylase activity in the intestines consistently peaked daily at about noon when the milkfish gut was full. In contrast, enzyme activity was significantly lower at 0030 hrs when the gut was empty. These results are consistent with earlier observations that the milkfish is a daytime feeder and suggest further that intestinal amylase secretion is in phase with the feeding activity of the milkfish. Although the fishes used in this study fed mostly on the naturally occurring algae in the ponds, no cellulase activity was detected in any region of the digestive tract. Less active carbohydrases that were detected include a β-glucosidase and β-galactosidase, both of which were of limited substrate specificity.

Notes: Abstract The respiration of 3 adult females of Cyclothone acclinidens was measured in situ. These numerically dominant fish of the meso- and bathypelagic zones were individually captured off southern California at a depth of 1300 m using a multiple-chambered slurp-gun respirometer operated from the submersible “Alvin”. Continuous oxygen consumption measurements of each fish were made at the capture depth for about 28 h, spanning an interval from late morning to the following mid-afternoon. Nocturnal rates of respiration of these fish were 3 to 5 times higher than diurnal rates, suggesting a daily thythm in this non-migratory midwater species. Environmental factors such as tides, light, and food could serve to synchronize the observed respiration fluctuation.

Notes: Abstract Red sea breams were kept at 20°C without food at 3 salinities (full sea water, 950 mOsm kg-1; 2/3 sea water, 640 mOsm kg-1; 1/3 sea water, 330 mOsm kg-1). In fish adapted to all 3 salinities, starvation resulted in marked decline of plasma FFA and β-hydroxybutyrate and liver glycogen levels but plasma glucose and lactate concentrations were maintained. These findings suggest that with the onset of starvation, enhanced hepatic glycogenolysis and decreased fat utilization occurred. Fish, adapted to full and 2/3 sea water, could not survive for more than 19 d without food. However, fish adapted to 1/3 sea water could tolerate 27 d of starvation. Enhanced survival during starvation in 1/3 sea water was observed to be associated with maintenance of plasma protein and elevation of hepatic glucose-6-phosphate dehydrogenase activity. It is suggested that sea breams be transferred to an iso-osmotic medium whenever the threat of starvation prevails, but this suggestion has yet to be evaluated in economic terms.

Notes: Abstract A flow-through system was used to follow naphthalene and naphthalene metabolite accumulation in the seawater and in the tissue of the oyster Ostrea edulis. After 72 h, 82.5% of the naphthalene carbon was recovered from the system. Glucose was added to seawater to stimulate the pathways of glucose metabolism in the oysters. Streptomycin (100 ppm) reduced microbial oxidation of naphthalene and glucose, and reduced bacterial growth. However, even in the presence of streptomycin, microbial oxidation of naphthalene was considerable. The main oxidation product recovered from seawater was 14CO2. Radioactivity was also associated with compounds which separated by TLC with 2- and 1- naphthol. The pattern of naphthalene uptake and accumulation in oyster tissues was relatively constant after only a few hours of exposure to naphthalene. The potential of tissues to accumulate naphthalene was shown to be a function of multiple variables such as nutritional state, lipid concentration, length of exposure to naphthalene, and the external naphthalene concentration. Carbon-14-labeled metabolites derived from 14C-naphthalene were consistently recovered from digests of the oyster tissues. Non-CO2 alkaline-soluble substances were the primary metabolites. Hexane-extractable substances, which separated by TLC with known standards of 2- and 1- naphthol, were consistently recovered from seawater and tissue digests. It was not possible to conclude that these metabolites were a result of naphthalene metabolism by oyster enzyme systems.

Notes: Abstract Photosynthetic parameters for netplankton (〉22 μm) and nanoplankton (〈22 μm) varied over similar ranges but exhibited different seasonal and geographic patterns of variation. Nanoplankton a was relatively constant (0.06 mg C [mg Chl · h]-1 [μE m-2 s-1]-1), but P m B (mg C [mg Chl · d]-1) was an exponential function of temperature independent of nutrient concentration and vertical stability in the euphotic zone. The temperature function gives a P m B of 24 at 25°C for nanoplankton growing in an estuarine environment characterized by high nutrient concentrations and a shallow, stratified euphotic zone. Variations in netplankton a and P m B were less predictable and were not correlated with temperature, nutrients or vertical stability. Chain forming diatoms with small cells were able to achieve high α (0.10 to 0.15) and P m B (20 to 24) that were 3 to 5 times higher than large-celled diatoms and dinoflagellates were able to achieve.

Notes: Abstract It is generally thought that the laterofrontal cirri of the bivalve gill act as filters that retain suspended particles in the through current and transfer the particles onto the frontal surface of the gill filaments. In Mytilus edulis calculations indicated that if water passed between the branching cilia of the cirri that are assumed to constitute the filter the pressure drop needed would amount to about 10 times the actual pressure drop across the whole gill. Thus, instead of acting as filters the laterofrontal cirri seem to move water. Presumably, the cirri together with the frontal cilia produce the water currents along the frontal surface of the gill filaments. Particle retention in the bivalve gill implies the transfer of suspended particles from the current of water about to enter an interfilamentar space into a neighbouring frontal surface current. The complex three-dimensional pattern of flow that arises where the 2 systems of current meet is characterized by steep velocity gradients. Particles that enter such steep, steady velocity gradients become exposed to transverse forces that cause the particles to migrate perpendicularly to the direction of flow. Whether particles enter the surface current, i.e. are retained, or they stay within the through current andescape, depends primarily upon particle size, and upon the steepness and height of the gradients within the boundary zone between the surface current and through current. Further studies are needed to evaluate the capacities and relative importance of this hydromechanical particle-trapping mechanism in suspension feeding bivalves. It is suggested that in downstream particle-retaining systems, e.g. on the tentacles of polychaetes and entoprocts, velocity gradients between through currents and surface currents also act as the particle-collecting mechanism.

Notes: Abstract The influence of suspended, natural silt (0 to 20 mg l-1) in addition to unicellular algal cells (Phaeodactylum tricornutum) (o to 20.000 cells ml-1) on clearance, growth and energetics in Mytilus edulis has been studied. Clearance increased by 32 to 43% by the addition of 5 mg silt l-1 as compared to clearance in a pure algal suspension. Ingestion and growth rate increased with algal concentration, and growth rate was further increased by 30 to 70% by the addition of 5 mg silt l-1. A growth rate comparable to maximum natural growth rates was reached only at the highest algal concentration in the presence of 5 mg siltl-1. Assimilation efficiency of P. tricornutum decreased from 77% at 5,000 cells ml-1 to 52% at 20,000 cells ml-1. In the experiments with silt added, some 20 to 30% of the assimilated organic matter originated from the suspended bottom material. Net growth efficiency increased with growth rate at a decelerating rate, approaching a maximum of about 70%. It is concluded that suspended bottom material, which is always present in M. edulis' natural habitats, serves as an additional food source, and that M. edulis depends on suspended bottom material to exploit fully its clearance potential, and to reach the maximum growth rates observed in nature.

Notes: Abstract Nitrification rates, measured in different sediment types from Danish waters, are in the range of 0.3 to 1.4 mmol NO 3 - m-2 d-1. There is no signification between sandy and muddy sediments, nor between shallow and deeper stations. The extent of nitrification is probably limited to the zone of oxygen penetration, 1.5 to 5.5 mm. There are, however, nitrifying bacteria located in the anoxic sediment layers. There relative numbers were found by measuring the “nitrification potential” of the sediment. These potential rates (22°C) can also be used to calculate actual rates of nitrification, by adjusting to in situ temperature and oxygen penetration. These calculated rates agree with the actual measured rates of nitrification for a wide range of sediment types and may be used for the estimation of actual nitrification rates. Nitrate flux out from the sediment/water interface is in the range of 0 to 0.7 mmol NO 3 - m-2 d-1. There is no correlation between concentration gradients of nitrate across the sediment/water interface and the measured flux of nitrate. Approximately 50% of nitrate production is released to the water column. The remainder (0 to 0.35 mmol N m-2 d-1) may have been denitrified.

Notes: Abstract Downwardly directed light-traps were used by night, over seagrass and coral sand to investigate the existence and significance of nocturnal peaks in phototactic zooplankton. Samples each half-hour from sunset to sunrise showed that small invertebrates, mostly copepods, were trapped in large numbers once or twice a night. Each period of high catches lasted only 1 to 2 h and was often associated with periods of failing natural light (evening twilight, moonset). This pattern and its variations are explained in terms of nocturnal vertical migration, in which plankton move towards light in response to decreasing light intensity, move away from light in response to increasing light intensity, and disperse at constant light intensity. Some morning peaks are unexplained.

Notes: Abstract The contribution of fecal pellets to the benthos of the southeastern shelf of the USA is investigated through an analytic model which considers pellet production by different stage groups of the genus Paracalanus. Model results indicate that the concentration and vertical flux of pellets is a function of producer size and consumer size and abundance. Nauplii and adults, respectively, produce daily on the average 50 and 13% of total pellet mass, yet contribute 4 and 63%, respectively, to the daily pellet flux. Most of the pellets produced are consumed or degraded in the water column, with only 0.2% of the average daily primary production reaching the seafloor (35 m) as fecal pellets. This contributes to an impoverished benthos, such as that found on the southeastern continental shelf.

Notes: Abstract A range of substrates has been examined in order to determine the types of attachment mechanism employed by marine bacteria. Use of the scanning electron microscope (SEM) has also allowed an investigation of the initimate relationship between an antifouling paint matrix and its attached bacterial community. Plastic (Thermanox) and glass coverslips, together with Cu2O-based and TPTF-based antifouling paints and their respective empty-matrix analogues have been used in this study. Observations over periods of up to 4 wk have shown that extensive bacterial communities can develop. A variety of bacteria have been found: cocci; various rods; stalked forms; and prosthecate types. These bacteria also exhibit a range of attachment mechanisms. Initial attachment is by simple stickiness of cell walls, flagella, pili (fimbriae) or stalks. This stickiness can be attributed to an actual adhesive, electrostatic forces, electrical double-layer phenomena or to London/van der Waals forces. Often, attachment is subsequently improved by the secretion of insoluble, high molecular weight, polysaccharidic material. This material is found in the form of strands, pads, sheets or capsules and acts to bridge the space between the cell wall and substrate or adjacent cells. Thus, stalked forms are found attached by basal pads of mucilage whilst cocci and rods are often found enmeshed in mucilage strands and sheets, but less often attached by pads and capsules. Initially, single bacterial cells attach and give rise to colonies by cell division. Continuing growth of adjacent colonies leads to the development of confluent films over the substrate surface. Further growth results in thickening until eventually the entire surface is coated with a dense community of mixed bacteria together with their adhesive mucilage. In the case of antifouling paints, the porous nature of the matrix allows invasion by bacteria and the possibility of pore blockage by adhesive polysaccharides. This problem is discussed with reference to the paint's loss of antifouling efficiency.

Notes: Abstract The water exchange between a small (4.1 hectare) salt marsh adjoining the Great Bay Estuary system of New Hampshire, USA was sampled during 16 tidal cycles between July, 1976 and November, 1977. Tidal amplitude, temperature, salinity, nutrient concentrations (ammonia-N, nitrate-N, nitrite-N, orthophosphate-P, total-P, silicates) and suspended particulates were measured. Conspicuous tidal hydrographic patterns were observed. Mean concentrations of nitrate-N and silicates varied with season. The tidal information, combined with volume determinations, was extrapolated to determine the net flux of hydrographic parameters on monthly and yearly bases. Ammonia-N showed a pronounced seasonality of net exchange by regression analyses. Ammonia-N and suspended particulates had a statistically significant import into the marsh. However, the net fluxes of the other materials were not statistically different from O.

Notes: Abstract Net photosynthetic oxygen evolution in Amphiroa anceps (Lamarck) Decaisne is inhibited at high oxygen concentrations. Photosynthesis is highest between pH 6.5 and 7.5. At pH 9 to 10 there is still a significant photosynthetic rate, suggesting that this alga can use HCO - 3 as a substrate for photosynthesis. At pH 7.0 to 8.5, the photosynthetic rate saturates at a total inorganic carbon concentration (ΣCi) greater than 3 mM. At pH 8.5 and 8.8, calcification rate continues to increase with increasing concentration of ΣCi. Between pH 7 and 9, the calcification rate in the light in A. foliacea Lamouroux is proportional to the photosynthetic rate, whereas at higher pH where the photosynthetic rate is very low, the calcification rate is stimulated by the higher concentration of CO 2- 3 ion. At all pH values examined, the calcification rate of living plants in the dark and of dead plants is directly proportional to the CO 2- 3 ion concentration, suggesting little metabolic involvement in calcification processes in the dark, whereas calcification in live A. foliacea in the light is influenced both by the photosynthetic rate and the CO 2- 3 ion concentration in the medium.

Notes: Abstract A symbiotic relationship between a damselfish (Stegastes fasciolatus) and 2 surgeonfishes (Acanthurus lineatus and A. leucosternon) is described. The damselfish, which is about 1/10 the size of the surgeonfishes, is concentrated in, and appears to prefer to be in, the feeding areas of the surgeonfishes. There is an average of one adult damselfish per adult surgeonfish feeding area. All 3 species defend their feeding areas against conspecifics and various other fishes that have similar diets, but there are few aggressive interactions between the cohabitants. Most of the interspecific defense of cohabited areas is provided by the surgeonfishes. The cohabitant species eat the same types of benthic microalgae, but only the damselfish eats microcrustaceans. It appears that the net cost to a surgeonfish of having a damselfish in its feeding area is very low because (1) biomass density of the damselfish is low, (2) it uses some food that the surgeonfishes do not use, and (3) it makes a small contribution to the defense of shared feeding areas. Even if there is a cost to the surgeonfish, the small size of the damselfish would allow it to take shelter from the surgeonfish, thus making it too costly for the surgeonfish to exclude it. Such cohabitation relationships, which may be quite common among reef fishes, represent a means by which the coexistence of species that use the same limiting resources is achieved.

Notes: Abstract The New Zealand sprat Sprattus antipodum (Hector) is phenotypically variable, with two body forms (deep and slender) being recognised in the Canterbury Bight of New Zealand. Electrophoretic analysis of tissue samples from the two body types showed them to be fixed for different alleles at two loci and to have very different allele frequencies at a further three loci. Heterozygosities of 0.088 and 0.104 were found for the deep type and 0.056 for the slender type. Genetic distances of 0.421 and 0.403 were found between samples of deep and slender types and 0.014 between samples of deep types. It is concluded that the two body types are separate species.

Notes: Abstract The pedal retractor muscle of Nassarius coronatus, unlike most mollusc muscles, contains high activities of both octopine dehydrogenase (159 IU g-1 wet wt muscle) and D-lactate dehydrogenase (40 IU g-1 wet wt muscle). Pedal retractor muscles show accumulation of octopine (increase of 4.7 μmol g-1 wet wt muscle), and a fall in arginine phosphate concentration (decrease of 4.1 μmol g-1 wet wt musscle) after exercise. During recovery from exercise, octopine returns to resting levels after about 120 min, D-lactate accumulates (5.1 μmol g-1 wet wt muscle), and arginine phosphate returns to resting levels within 30 min. D-lactate (2.0 μmol g-1 wet wt muscle) accumulates during long-term exposure to air. The results show that octopine dehydrogenase and D-lactate dehydrogenase can function to catalyze the terminal step of glycolysis during muscle anoxia associated with these different physiological states.

Notes: Abstract Earlier studies on reproductive behavior of the tautog Tautoga onitis under laboratory conditions indicated that differences in courtship and spawning behavior were apparently related to the number of males attempting to spawn with a female. It had also been conjectured that certain ecological factors such as availability and distribution of food and shelter would play a role in the establishment of territoriality and defense of a female, indirectly influencing courtship activities and the resultant spawning mode. In the present work we have examined this question more closely by varying the number of males, females and amount of shelter available. Regardless of the social situation, in every instance single males, through aggression, attempted to limit access to a female and pair spawn. The degree to which this succeeded depended on the male's place in the dominance hierarchy, the number of males in proximity which were actively attempting to spawn and the availability of shelter. Courtship activity of the female was influenced by the amount of male attention. When attention was high, the nuptial shading of the female never developed maximally. On the other hand, when male attention was low, the female showed progressive and maximal shading development to attract males. The significance of the findings is discussed.

Notes: Abstract Salps (mainly Salpa fusiformis and, to a lesser extent, Pegea socia) and a web-building pteropod (Corolla spectabilis) were studied in epipelagic waters of the central California Current. Although both kinds of gelatinous zooplankton trap phytoplankton in a mucus net, a fecal pellet analysis indicated that their diet differs significantly when they feed together, probably because of differences both in the pore sizes of their nets and in their feeding methods. Salps have a finemesh filter, on which they can retain even the smallest phytoplankton; thus, when small coccolithophores are abundant, as they were in our study, salp feces contain such cells and the coccoliths derived from them. In contrast, pteropods feeding in the same area produce fecal pellets consisting chiefly of larger phytoplankton, especially diatoms. Since fecal pellets transport most biogenic material to the deep sea, changes in herbivore species composition at a given geographic location can change the chemistry of materials entering deep water; at our study site, the more salps, the greater the calcite flux, and, the more pteropods, the greater the silica flux. In addition, fecal pellets of both salps and pteropods include partially digested residues of phytoplankton that appear as olive-green spheres, having an ultrastructure identical with that of the socalled olive-green “cells.” Presumably, fecal pellets, after sinking into deep water, ultimately disintegrate. releasing both the viable phytoplankton and the olive-green spheres into aphotic waters. Thus the feces of epipelagic herbivores are likely sources of much of the flora of the deep ocean.

Notes: Abstract Energy charge (EC) ratios of microplankton samples have been measured from their adenosine triphosphate (ATP), adenosine diphosphate (ADP) and adenosine monophosphate (AMP) contents, according to a method based on enzymatic tranformations of ADP and AMP into ATP, and the subsequent quantitative analysis of the latter by the bioluminescent reaction of a firefly lantern extract (Photinus pyralis). Interference caused by other non-adenylic nucleotides and bioluminescence inhibition by various compounds were reduced, or estimated, by the use of internal standards for each sample. This was accomplished both by the injection of a small volume of a non-commercial extract of P. pyralis and by measurement of the bioluminescent flash at its maximal value. This standard method for preparation and analysis afforded good reproducibility and permitted the calibration of individual samples, thus allowing the comparison and treatment of data in the large series necessary in oceanographic studies. Studies were made on natural populations taken from a polluted marine area where phytoplankton communities live under the stressful influence of an urban sewer outlet, near Marseille (France). Three sampling strategies in surface waters (transects from the outlet, sampling during a 24-h buoydrift, and regular sampling for a day-night period) conducted at a point in front of the outlet revealed a decrease of EC in relation to urban activity or approaching proximity of the sewer outlet. These low EC values (0.2 to 0.5) were caused by a high AMP content, perhaps originating from degraded biogenic particles and dead or “metabolically impeded” bacteria of terrestrial orgin stressed by ecologic factors such as increased salinity and decreased temperature. Further away from the sewage outlet, the EC increased as the bacterial population decreased, and the phytoplanktonic communities reappeared parallel to the dilution of the effluent. Although in mature and unperturbed ecosystems EC values of 0.70 to 0.80 were recorded, the values were generally lower than those measured in growing bacterial or phytoplankton cultures. This fact may be related to differences in the various metabolic states of multispecific populations. Some EC measurements from deeper microplankton samples presented in this paper were difficult to interpret, reflecting perhaps unsolved problems concerning the treatment of samples. However, it was possible to associate the range of variation in EC values to differences in composition and structure of the ecosystem of microplankton populations in neritic surface waters.

Notes: Abstract Kelp regeneration was observed for the first time in St. Margaret's Bay, Nova Scotia, Canada in an area known to have been devoid of macroalgae for several years. The regeneration was destroyed by sea urchins within 10 months. Experimentally induced kelp regeneration met a similar fate under normal grazing pressure. At the lowest sea urchin biomass and density encountered re-establishment of mature kelp stands seems highly unlikely. The sea urchin population required to suppress kelp regeneration is fed by benthic microalgae. Diatoms and other pioneer algal community species were found in the guts of sea urchins. The mean standing crop of benthic microalgae was found to be, 2.2 g C m-2 and production estimated as ca 15 g C m-2yr-1 at 8m depth. Most of the primary production of St. Margaret's Bay has been lost with the disappearing kelp populations.

Notes: Abstract Ammonia excretion of the Utah strain of Artemia sp. grown in axenic culture media was followed throughout the different stages of larval development. The ammonia accumulated in the culture medium does not affect ammonia excretion rates under our laboratory conditions. Growth rate, density and starvation all affect ammonia excretion. Ammonia excretion is directly related to the numerical growth index and inversely related to Artemia sp. density. Starved adult Artemia sp. excrete considerably lower amounts of ammonia than brine shrimp grown in nutritive medium. In view of the difficulties often encountered in estimating the excretion rates of small crustaceans, our culture conditions would appear advantageous for further studies on the purine metabolism of Artemia sp.

Notes: Abstract Gravid female Uca pugilator (Bosc) maintained in conditions of 14h L: 10h D light regime and constant temperature without simulated tides showed a significant positive correlation between time of hatch and time of the nighttime high tide. Light: Dark experiments showed no entrainment by LD cues. Larval hatching was delayed until dark when high tide occurred between 1900 and 2130 hrs. Hatch time was a positive linear function of the time of the nighttime high tide when high tide occurred after 2130 hrs. Time of hatch was delayed by the light period on days lacking a nighttime high tide. Experiments conducted under constant light (LL) and temperature, without simulated tides, indicated a persistent free-running rhythm of approximately 25 h 03 min, suggesting an endogenous timer. Rhythmic larval release on the nighttime high tide may be adaptive as a predator-avoidance mechanism for adult gravid females.

Notes: Abstract Grafting experiments have provided direct evidence for the occurrence of strain specificity in the marine demosponge Verongia longissima (Carter). All autografts accepted, all xenografts rejected, and there was both acceptance and rejection of allografts. Among allografts, groups of individuals could easily be identified which showed consistent acceptances and rejections of other individuals. The groups were designated as strains. Histological preparations of graft rejections showed the development of a cuticle between the surfaces of the two sponges in contact. The role of specificity in patterns of interactions between sponges in situ has been discussed from an ecological perspective.

Notes: Abstract The structure of the reproductive system in Copepodite Stages IV and V of the marine copepod Calanus finmarchicus (Gunnerus) is described, together with seasonal variations in gonad development and sex ratio, from Balsfjorden (69°21′N; 19°06′E), a subarctic fjord in northern Norway. The genital system in Copepodite Stage IV consists of a small gonad with two genital ducts. The gonad of Copepodite Stage V in its most immature condition resembles that seen in Copepodite Stage IV, whereas the sex of Stage V copepodites with mature gonads can be easily and reliably determined. The genital ducts are the key characters for separating males and females in Copepodite Stage V; potential males have one and potential females two genital ducts connecting the gonad to the genital opening on the first urosome segment. Adults males were rare compared to females, and were only in the majority at the end of January and beginning of February. The sex-ratio also favoured females in Copepodite Stage V. Seasonal peaks in the proportion of adult males reflected peaks of males in Copepodite Stage V, suggesting that seasonal variations in the adult sex-ratio are a direct result of a situation which has already been determined in Copepodite Stage V. The seasonal variation in gonad development in Copepodite Stages IV and V of C. finmarchicus reveals that the size of maturity of the gonad varies throughout the year. This study indicates that visible sex-differentiation in Stage V and moulting into adults occurs in Balsfjorden at least 2 months before spawning in April. Phytoplankton levels are immeasurable before the spring diatom increase starts at the end of March, implying that development and maturation of gonads are dependent upon internal energy resources, whereas the final act of spawning seems to require energy input from phytoplankton.

Notes: Abstract The concentrations of total dissolved carbohydrate (TCHO), monosaccharide (MCHO) and polysaccharide (PCHO) were followed over a total of ten diel cycles in a salt marsh and a 13 m3 seawater tank simulating an estuarine ecosystem. Their patterns are compared to those for total dissolved organic carbon (DOC), ΣCO2, pH, O2, chlorophyll a, phaeopigments and solar radiation. During 5 of the 6 marsh studies, PCHO underwent periods of sustained accumulation starting in the late morning or early afternoon and continuing into the early evening. These periods possibly represent release of recently synthesized PCHO from phototrophs. similar patterns were not found in the tank although direct associations between TCHO and phaeopigment dynamics suggest that zooplankton excretion was an important source of dissolved carbohydrate. The numbers of planktonic bacteria determined in one tank study increased rapidly during a late morning PCHO pulse and varied inversely with PCHO throughout the afternoon and evening, indicating that they were able to respond rapidly and control natural substrate concentrations on a time scale of a few hours. MCHO fluctuated to a much lesser extent than PCHO at both locations with levels possibly maintained near the bacterial uptake threshold or in a closely regulated steady state. TCHO concentration changes over 2-to 3-h sampling intervals suggest very rapid net system release and uptake with summer rates frequently exceeding 30 μg C l-1h-1 in the marsh and 20 μg C l-1 h-1 in the tank.

Notes: Abstract During 1978 and 1979 specimens of Nephtys hombergii in the River Tyne estuary (North East England) became gravid during the winter but did not spawn in the spring breeding season; instead their gametes were resorbed. The drastic effects of these spawning failures were apparent in the population structure in 1980, when the 1978 and 1979 year-classes were shown to be virtually absent, by the size of the individuals in the population and the numbers of growth lines in their jaws. The population structure in 1975, by contrast, indicated that recruitment during the preceding 4 to 5 yr had been good. Spawning was also effective in 1980, and an 0 group was detected in August 1980. Comparable data has been obtained for N. caeca, which occurs in the same beach. It shows that recruitment of this species during 1976–1980 was consistently good, whereas analysis of the age-class frequencies suggests that recruitment of N. caeca was poor in 1973 and 1975. The dominance relationship of the two species in the beach has been reversed during the period 1975–1980. It is suggested that the sympatric distribution of the two species is maintained in part by periodic reproductive failure. The causes of this are not yet known; possible reasons, including the extremely cold conditions experienced in 1978–1979 are discussed. The difference in frequency of the 1978, 1979 and 1980 year classes will now permit a rigorous evaluation of the relationship between the number of growth lines in the jaws and age in N. hombergii.

Notes: Abstract The conversion efficiency (gross growth efficiency) of larval Fundulus heteroclitus fed newly hatched Artemia sp. nauplii was recently reported as the lowest observed (0.69 to 1.11%) for a fish. A recalculation of the efficiencies, based on data from Radtke and Dean, showed that the original determinations were in error by two orders of magnitude. The recalculated values (69.0 to 114.4%), however, are impossibly large and probably result from measurement error in the determination of the weight of a single prey individual (nauplius). Using a nauplius weight estimate from the literature, the conversion efficiencies were again recalculated. The new efficiencies (25 to 41%) agree with those reported for other fish species. The values are still higher than those reported elsewhere for adult F. heteroclitus, but this is consistent with the generalization that conversion efficiency decreases with age.