ALBERT

Description: Two case studies of the application of geoscientific maps for planning in semi-arid regions are presented, one for the Mediterranean province of Valencia and another for the island of Gran Canaria (Canaries). Both regions are very dynamic from the point of view of population growth and urban-touristic-industrial development, and they suffer from a serious degree of environmental degradation. The provincial/ island governments have undertaken programmes of geoscientific mapping and assessment to serve as a basis for the establishment of guidelines for future planning. Two map sets have been made (1:200,000 in Valencia and 1:50,000 in Gran Canaria), based on initial maps of homogeneous integrated units. These represent a series of hierarchical land subdivisions, progressively smaller and more detailed (morphodynamic environments, systems, units, elements), defined on the basis of morphostructure, climate, lithology, surficial deposits, landforms, topography, active processes, soils, vegetation and human influence. Each individual map unit is described by means of a form which includes 114 items, summarising its environmental features. Morphodynamic units have been evaluated in terms of qualities significant for planning, and a series of derivative maps has been developed (geologic hazards, soil capability, present degree of erosion, potential erodibility, quality for conservation). A final map shows the most advisable types of uses and the main limitations for human activities, mainly due to engineering geological factors. This is a synthesis document which can be used directly by planners.

Description: We studied the distribution and abundance of marine birds in Bransfield Strait and southern Drake Passage during January and February 1985. We identified clusters of bird species, “communities” with similar distributions, and examined the extent to which the distributions of these seabird communities reflected the underlying physical oceanography of the region. Based on temperature, salinity and silicon data, we identified 11 water masses which resulted from varying degrees of mixing of water from the Pacific Basin, the Bellingshausen Sea, the Weddell Sea and terrestrial runoff. Seabird species assemblages were associated with contiguous clusters of water masses, suggesting a response by the birds to apparently subtle differences in their marine habitat.

Description: The present paper demonstrates the application of serological methods to the identification of fish prey in the diets of marine mammals. Antisera were raised to muscle protein extracts of cod Gadus morhua Linnaeus, herring Clupea harengus Linnaeus and salmon Salmo salar Linnaeus. The antisera were tested for reaction with protein extracts from raw and in vitro digested fish muscle; stomach contents of captive dolphins Tursiops truncatus Montagu fed on known dites; digestive tract contents of seals Halichoerus grypus Fabricius and Phoca vitulina Linnaeus which contained hard remains of known prey species; and faeces of captive seals fed on known diets. The salmon antisera were shown to be sufficiently strong and specific to be used for identification of salmonid proteins in digestive tract contentc of marine mammals, and were potentially applicable to screening seal faeces. Antisera raised to cod and herring were less successful, due to low speificity and low titre, rspectively. The potential exists to develop this methodology for routine identification of a range of prey species in marine mammal diets.

Description: Feeding trials in which salmon was fed to captive seals are described and sources of evidence for the presence of salmon in the diet of seals are evaluated. In faecal samples, the recovery rate of salmon otoliths is too low and bony remains are too fragmented to be useful. Protein extracts from the faeces of salmon-fed captive seals will react with anti-salmon antisera, but the reaction is not strong enough for the methods to be presently applied to field samples. In the digestive tract samples from seals, the use of bony remains for the identification of salmon significantly increases the probability of recognising this species. Protein extracts from digestive tract contents will react positively with anti-salmon antisera and this shows that serological methods can provide evidence for the presence of Salmonidae in the diet of seals, in the absence of solid remains.

Description: Growth increments have been reported to occur in the squid beak, radula, gladius and statolith. Of these, the statolith, which is part of the organ responsible for detection of linear and angular acceleration, has proved most promising for age determination. Growth increments in the statolith are formed from aragonite crystals in an organic matrix. They are best viewed after sectioning the statolith or after decalcification in weak acid. The statolith grows in concert with the rest of the squid. Experiments with squid in which chemical markers have been incorporated at a known time in the statolith, and experiments with cultured squid of known age, appear to confirm the hypothesis that growth increments in the statolith are laid down daily. Increments are produced in the laboratory in the absence of tidal, feeding or temperature cycles, which suggests that there is a firmly entrained endogenous circadian rhythm associated with their formation. However, the possibility that increment formation can be disrupted by environmental factors, or that rings in the statolith are produced coincidentally at the rate of approximately one per day, should not be fully discounted without further experimental corroboration. Data on squid age, derived from growth increments in the statolith, clearly have value in fisheries investigations, but they should be treated with caution until they have been validated.

Description: The scientific basis for managing the short fin squid, Illex argentinus, Stock around the Falkland Islands is presented. A target proportional escapement policy is used which permits a level of fishing effort compatible with conservation targets to be set each year. This policy is intimately related to the method of assessing stock size and the rate of fishing mortality presented in a related paper. The results of applying this management procedure for the 1987 and 1988 fishing seasons, the first 2 years of regulated fishing in Falkland Islands waters, are described. The policy has the considerable benefit that the data requirements and monitoring procedures are straightforward, and can be implemented by the limited manpower resources of the islands.

Description: The fine fraction of surface sediment samples in the Norwegian Sea shows an unexpectedly high amount of calcareous nannoplankton. Investigations, using time-series sediment traps in the Lofoten Basin (69°N, 1983/84), near Bear Island (75°N, 1984/85) and in the Fram Strait (78°N, 1984/85) provided information about the accumulation of this material in relation to the strong seasonality of biological production. Coccolith identification and counting, by means of a scanning electron microscope, indicated that the coccolith assemblages in the traps consist almost entirely of the two speciesEmiliania huxleyi andCoccolithus pelagicus. These species dominated the flux rate of the nannoplankton carbonate. A further eight species only made minor contributions to the flux. In the Lofoten Basin a distinct seasonality could be recognized in both standing crop and carbonate flux. Also the relationship between the two main species and the proportion of intact coccospheres showed an annual cycle. In the sample series of the two northerly traps the seasonality was less distinct. In general, the coccolith flux decreases towards the North. This was particularly evident for the smaller speciesE. huxleyi, while the number of massiveC. pelagicus coccoliths — and so the coccolith carbonate flux — diminished only slightly. Additional investigations on water samples from the Norwegian Sea revealed species compositions that differed greatly from those in the sediment traps. This suggests that selective processes change the relative species proportions during sedimentation.

Description: Brain pathways controlling the chromatophores of the squidLolliguncula brevis are described using cobalt iontophoresis. The results show several input and output pathways of the anterior and posterior chromatophore and lateral basal lobes. These connections allow coordination and modification of the chromatophore motor program throughout the motor pathway. Unlike other cephalopod species, there seems to be no direct input from the optic lobes to the lateral basal lobes inL. brevis. This species displays only a few simple patterns; therefore the underlying neural pathways for chromatophore control may be different from those of other cephalopods with more extensive patterning repertoires.

Description: Mean intracellular pH (pHi) and PCO2 (PiCO2) have been analysed based on pH and total CO2 measurements in tissue homogenates. Tissues were sampled from undisturbed worms (Sipunculus nudus), squid (Illex illecebrosus), trout (Salmo gairdneri), toads (Bufo marinus), and rats. Homogenate metabolism was inhibited by the addition of potassium fluoride and nitrilotriacetic acid (NTA). Model calculations revealed that the influence of dilution, medium buffers, and contamination by extracellular fluids was negligible. In white muscle tissue the resulting pHi values were virtually the same as found in studies using DMO (dimethyloxazolidinedione). If large fractions of mitochondria were present (e.g. in heart muscle), DMO derived pHi values were considerably higher, probably representing overestimates. Homogenate derived pHi values are concluded to represent the effective mean pHi by taking into account pH gradients, and the volumes and buffering of cellular compartments. High time resolution and small variability make this method especially useful to assess rapid changes in pHi, e.g. in exercising animals.

Description: The organization of the chitin-proteoglycan in Loligo vulgaris pen was examined ultrastructurally and related to the molecular order indicated by X-ray diffraction. There is a centrosymmetric striated repeat of 22 nm in the system which is based upon dark and light bands of unequal width. The banding is orientated perpendicular to the direction of the major molecular axis of the chitin fibres. The chitin molecules are laid down in sheets with a mutual, though irregular, twist to produce a laminated ‘plywood’ material.