ALBERT

Description: The Hg concentration in horned octopus was studied in relation to its biological cycle. The metal was measured in the muscle tissue of specimens of different size, sex and maturity. This species proved to be a strong accumulator of mercury, whose concentration was found to be correlated with length independently of the sex. The relationship with size was found also for the organic form. Consideration was given to the danger of frequent consumption of this cephalopod and to its use as a biomonitor of environmental mercury impact.

Description: 1. The salivary enzymes of the octopus Eledone cirrhosa were separated using isoelectric focusing techniques (IEF) and HPLC. 2. The use of casein zymograms allowed the detection of at least 10 caseinolytic bands in analytical IEF gels and a preliminary, based on pI values, is described. 3. There appear to be two salivary chitinases. 4. Using HPLC, it was possible to separate the most cationic of these from the proteolytic enzymes of similar pI.

Description: Changes in marine ecosystems can be manifested in many different ways, on different temporal and spatial scales. Seabirds are top consumers in marine foodwebs and offer opportunities to detect and assess the biological effects of changes in physical parameters (sea-surface temperature [SST], salinity, depth of thermocline etc.) of the marine ecosystem. We compare six-eight years' of data on the biology (diet, and breeding success) of four species of seabird (arctic tern Sterna paradisaea and common tern S. hirundo, which feed at the sea surface; and Atlantic puffin Fratercula antica and razorbill Alca torda, which dive 30-60 m for their prey) breeding on Machias Seal Island (MSI) in the Bay of Fundy with both our own meteorological and oceanographic measurements, and with standard measurements from conventional sources. These are compared with fisheries data on changes in the main prey of all the seabirds concerned (juvenile or '0-group' herring Clupea harengus) which are the most direct link between the seabirds and the physical properties of the marine system. We explore relationships between seabird productivity and diet, and other aspects of both herring biology (larval surveys, and fat content) and oceanography (SST data from the island, and remotely sensed data from the entrance to the Bay of Fundy). Timing of laying by puffins followed SST variation at neither the local (MSI) nor regional scales, but at the scale of the North Atlantic, following the trend of populations breeding off northern Norway. The proportion of herring in the diet of terns over 6 years varied inversely with herring larval abundance the previous fall; this relationship was not statistically significant in the puffin and razorbill. A major new finding is the considerable (approximately 50%) inter-annual variation in the energy density (fat content) of juvenile herring that are the main seabird prey; breeding success of both species of tern varied in parallel with the energy density of juvenile herring in the diet until the last two years of the study, when sandlance (Ammodytes sp.) and euphausid shrimp predominated in the diet. Our long-term research approach combines traditional population monitoring (of numbers of breeding birds) with demographic, behavioural and environmental monitoring, to provide new understanding of the marine ecosystem as well as of seabirds.

Description: Coupling between surface water plankton and abyssal benthos was investigated during a mass development of salps (Salpa fusiformis) in the Northeast Atlantic. Cyanobacteria numbers and composition of photosynthetic pigments were determined in faeces of captured salps from surface waters, sediment trap material, detritus from plankton hauls, surface sediments from 4500–4800 m depth and Holothurian gut contents. Cyanobacteria were found in all samples containing salp faeces and also in the guts of deep-sea Holothuria. The ratio between zeaxanthin (typical of cyanobacteria) and sum of chlorophyll a pigments was higher in samples from the deep sea when compared to fresh salp faeces, indicating that this carotenoid persisted longer in the sedimenting material than total chlorophyll a pigments. The microscopic and chemical observations allowed us to trace sedimenting salp faeces from the epipelagial to the abyssal benthos, and demonstrated their role as a fast and direct link between both systems. Cyanobacteria may provide a simple tracer for sedimenting phytodetritus.

Description: A mechanistic account of skeletal density band formation in massive colonies of Porites is developed by linking observations from vital staining of growing skeletons with measurements of density band characteristics, dissepiment spacing and the depth to which skeleton was occupied by tissue. Three growth processes contribute to density band formation. First, addition of new skeleton at the outer surface of the colony. Second, thickening of existing skeleton through the depth of the tissue layer (tissue usually occupies skeleton formed over the last 4–13 months). Third, the density pattern is then modified by periodic and abrupt uplift of the lower margin of the tissue layer which occurs about every 30 days. Uplift is associated with formation of new dissepiments and produces a fine density band at the lower margin of the tissue layer. Less regular, fine bands are formed within the tissue layer probably as a result of variations in calcification at the colonial surface. X-radiography of skeletal slices compresses and combines the results of these mechanisms making it difficult to distinguish the contribution of individual mechanisms to the overall X-ray image. The relative importance of the three mechanisms — extension, thickening and tissue uplift — to overall skeletal growth may differ between individual colonies. Variability in the way the mechanisms operate and combine may account for widely differing reports of coral density banding.

Description: Accurate congener-specific determination of chlorobiphenyl congeners (all 209 congeners) is finally possible with the use of multidimensional gas chromatography-electron-capture detection techniques. The effectiveness of this technique for environmental analyses is enhanced by ultraclean laboratory practices, non-destructive extraction and clean-up steps and the use of low-volume, high-efficiency HPLC separation for various classes of organic contaminants. In the light of these new developments conventional procedures for chlorobiphenyl analysis are evaluated.

Description: During a R.V. Meteor JGOFS-NABE cruise to a tropical site in the northeast Atlantic in spring 1989, three different vertical regimes with respect to nitrate distribution and availability within the euphotic zone were observed. Besides dramatic variations in the depth of the nitracline, a previously undescribed nose-like nitrate maximum within the euphotic zone was the most prominent feature during this study. Both the vertical structure of phytoplankton biomass and the degree of absolute and relative new production were related to the depth of the nitracline, which in turn was dependent on the occurrence/non-occurrence of the subsurface subtropical salinity maximum (S(max)). The mesoscale variability of the nitracline depth, as indicated from a pre-survey grid, and published data on the frequent occurrence of the S(max) in tropical waters suggest higher variability of new production and F-ratio than usually expected for oligotrophic oceans. The importance of salt fingering and double diffusion for nitrate transport into the euphotic zone is discussed.

Description: In April 1990, 488 marine fish belonging to 30 species from central Phillipine waters were examined for flesh parasitic infections that may affect their consumability. One species of hemirhamphids and 3 species of belonids harboured plerocercoids of Otobothrium penetrans Linton, 1907 (Proceedings of the U.S. National Museum33, 85–126). This is the first record of this parasite from Pacific fish species. The highest intensity of infection found was 8 in Tylosurus crocodilus. Most of the larvae were located between the dorsal spines of the vertebral column, only 32% were found in the fillets. Based on the present material we give a description of the plerocercoid stage of the species using scanning electron microscopy of the armature and morphometrical measurements. Comparison to results from earlier findings of O. penetrons by Linton (1907; 1924, Proceedings of the U.S. National Museum64, 1–114) and to O. kurisi by Shields (1985, International Journal for Parasitology15: 635–643) lead to the conclusion that the latter species is a synonym for O. penetrans.