The feeding rates ofPleurobrachia (ctenophora) andSagitta (chaetognatha), with notes on the potential seasonal role of planktonic predators in the dynamics of north sea zooplankton communities

The zooplankton off the north-east coast of England has been the subject of a number of studies focusing on its productivity. It has also been shown to be representative of the zooplankton of much of the western North Sea. The community contains a number of predatory species, three of which are widely described as ‘voracious’, the ctenophorePleurobrachia pileus, the chaetognathSagitta elegans and the hyperiid amphipodThemisto compressa (≡ Parathemisto gaudichaudi). This study investigates the role of these planktonic predators in this community, with special reference to the seasonal changes in predation pressure. The functional response ofPleurobrachia pileus feeding onAcartia was determined from laboratory experiments. It was found to be linear at prey densities typical of UK coastal waters, although the linear relationship appeared to break down at low and high prey densities. Feeding rate data forSagitta elegans were obtained from gut content analysis and published laboratory derived estimates of digestion time. Of the 1,789 individuals examined 198 (11.1%) had food remains in the gut. A linear relationship betweenSagitta length and prey size was established and the daily feeding rate ofSagitta elegans was estimated to be 0.4 prey items d⁻¹ ind⁻¹. For comparative purposes, the proportion of the copepod standing stock removed bySagitta elegans, Pleurobrachia pileus andThemisto gaudichaudi was estimated for each month of the year. From this model it was shown thatThemisto applied the most predation pressure, andSagitta elegans applied the least predation pressure of the three planktonic predators considered. The impact ofPleurobrachia will be to a large extent offset due to its peak of seasonal abundance coinciding with the zooplankton peak in the summer.     

The invasive worm Hydroides elegans (Polychaeta – Serpulidae) in southeastern Brazil and its potential to dominate hard substrata

The serpulid Hydroides elegans is recognized as an invasive species in many harbour areas of the world, growing mainly on man-made structures such as pier pilings, where native diversity is low. In addition, because they build large aggregations of calcareous tubes, this increases the maintenance and fuel costs of vessels. While H. elegans is well known for the North Atlantic, Europe, Caribbean and Pacific Ocean, detailed information of the species for the South Atlantic is missing. In the last decade, owners of boats moored at the Clube Naval Charitas (CNC), in the Guanabara Bay, southeastern Brazil noticed an increase in the occurrence of an encrusting organism that we identified as H. elegans. In this study we characterize H. elegans specimens from CNC and Itaguaí Harbor, both in southeastern Brazil, and discuss its distribution in the world. In addition, we deployed PVC panels at two different depths to quantify how H. elegans affects community assembling over two months. We observed that H. elegans could dominate hard substrata in the intertidal zone, occupying more than 50% of the available substrata. Considering the damage caused by H. elegans elsewhere and the ability of the species to monopolize space in the intertidal zone demonstrated here, accurate taxonomic information is essential for future monitoring and management of the species in Brazil and the South Atlantic.     

Benthic invertebrates as indicators of organic pollution in the Western Baltic Sea

The quantitative distribution of some important benthic invertebrates in a shallow inshore area of Kiel Bay (Western Baltic Sea) is described. This region is partly polluted by domestic sewage from the municipality of Kiel. Three groups of species are distinguished with reference to their densities and other population parameters in the different subareas: Progressive species of the 1st and 2nd order indicate a high and moderate to slight degree of pollution respectively by high population numbers. Regressive species are adverse indicators, absent or occurring in exceptionally low numbers in affected areas. In many cases the examination must be concentrated on sand bottom, because a series of species normally dwelling on aufwuchs build up dense populations in sand, if it is organically enriched. The polychaetes Capitella capitata, Nereis diversicolor and Polydora ligni are regarded as progressive species of the 1st order. The amphipods Corophium insidiosum and Gammarus salinus, the mussel Mytilus edulis, the polychaete Pygospio elegans, the snail Hydrobia ulvae, and some other invertebrates belong to the group of indicators for slight organic pollution. The main regressive species are the amphipod Bathyporeia sarsi and the mite Copidognathus fabriciusi.     

Long-term studies of macrozoobenthos in intertidal and shallow subtidal habitats near the island of Norderney (East Frisian coast,Germany)

Near the East Frisian island of Norderney two sites are investigated permanently in order to study long-term fluctuations of macrozoobenthos: one transect (since 1977) at the northern side in shallow subtidal waters and another one (since 1976) at the sheltered southern side in the intertidal area of the Wadden Sea. Since 1980 the investigations have been continued in the frame of COST-47, sedimentary intertidal programme (including the shallow subtidal habitats colonized by the Macoma balthica community).The results up to 1984, respectively to 1985, are presented and the changes of abundance of the dominant species are discussed. Discussed are also the influences of water temperatures and sediment disturbances caused by wave action. There is evidence that the intertidal variety of the Macoma balthica community shows a greater stability than the subtidal variety.     

Heterochrony in mandible development of larval shrimp (Decapoda: Caridea)—A comparative morphological SEM study of two carideans

Mandible development in the larval stages I–V of two palaemonid shrimp species, Palaemon elegans and Macrobrachium amazonicum, was analyzed using scanning electron microscopy, light microscopy, and confocal laser scanning microscopy. In contrast to the zoea I of P. elegans, first‐stage larvae of M. amazonicum are nonfeeding. At hatching, the morphology of the mandibles is fully expressed in P. elegans, while it appears underdeveloped in M. amazonicum, presenting only small precursors of typical caridean features. In successive zoeal stages, both species show similar developmental changes, but the mandibular characters of the larvae in M. amazonicum were delayed compared to the equivalent stages in P. elegans, especially in the development of submarginal setae and mandible size. In conclusion, our results indicate heterochrony (postdisplacement) of mandible development in M. amazonicum compared to that in P. elegans, which is related to initial lack of mandible functionality or planktivorous feeding at hatching, respectively. This conclusion is supported by comparison with other palaemonid zoeae exhibiting different feeding modes. Our data suggest that an evolutionary ground pattern of mandible morphology is present even in species with nonfeeding first‐stage larvae. J. Morphol. 275:1258–1272, 2014. © 2014 Wiley Periodicals, Inc.     

Effects of green algal mats on bivalves in a New England mud flat

Concurrent with the spread of green algal mats on tidal flats, reports of macrofauna dieoffs under dense algal mats have increased in numbers. Bivalves seem to be particularly affected by persistent dense algal mats. Bivalve species with a long extendible siphon seem to be less affected underneath algal mats, but no distinction has been made in the past between species with short and those with long siphons,Mya arenaria andMacoma balthica, on an intertidal mudflat in New England. Abundances ofM. arenaria declined substantially during the study period when a thick green algal mat covered the mudflat for several months. Numbers of the small bivalveGemma gemma also decreased substantially, whereas abundances ofM. balthica showed minimal variation during the time of algal coverage. In algae removal/addition experiments numbers ofM. arenaria decreased, but effects were only significant in an algal addition to previously algal-free mudflat areas. Abundance ofM. balthica did not change significantly in the algal removal/additition experiments. Over the time period of the experiment (9 weeks),M. arenaria showed measurable size increase in uncovered mudflat areas, but not underneath algal mats. Similarly,M. balthica only increased in size in the uncovered mudflat area. From these results it is concluded thatM. balthica can survive time periods of dense algal coverage because it is able to penetrate through the algal mat with its long extendible siphon, and thus can reach well-oxygenated water layers above the mat.M. arenaria with its thick, less extendible, siphon cannot push through dense algal mats and therefore is more likely to die underneath persistent algal mats.     

Dense aggregations of tube-building polychaetes: response to small-scale disturbances

Many species of tube-building polychaetes form dense aggregations or ‘patches’ within marine soft-bottom habitats. Although the ecological importance of such patches has been well studied, the effect of small-scale disturbances within patches has not been investigated. On the intertidal sandflat Drum Sands, Firth of Forth, Scotland, the tube-building spionid Pygospio elegans Claparède forms patches approximately 1-1.5 m², wherein its density is significantly greater than in surrounding sediments. This study explicitly investigates whether the initial communities colonising small-scale disturbances within P. elegans patches differ in terms of community structure and colonisation mode from those of surrounding sediments.Defaunated sediments (1/125 m²) were implanted into the sediments within and outside patches during April, August and December 1997, and sampled after 3 weeks. The results indicated that some species colonised patches and non-patches in significantly different numbers, at least at certain times of the year. Following these controlled disturbances, P. elegans larvae colonised patches in significantly higher numbers compared to non-patch areas during April 1997, but showed the opposite trend in August 1997 when larval recruitment was relatively low. Adult P. elegans colonised patch sediments in higher numbers than non-patch ones during August and December. Capitella capitata (Fabricius) consistently colonised all defaunated areas in relatively high numbers while Cerastoderma edule (L.) and Macoma balthica (L.) colonised non-patch azoic sediments in significantly higher numbers than patch azoics during April 1997. Multivariate analyses, together with nonparametric analysis of similarities (ANOSIM) tests, revealed that the community composition of the disturbed sediments was significantly different between patches and non-patches during April 1997 only. These analyses also indicated that there was a strong temporal effect on community composition since the April community was markedly different from those of August and December 1997. Sediment measurements taken during December suggested that the observed faunal differences were unlikely to have been a response to differences in bulk sediment characteristics or redox potential.It is proposed that the initial recolonisation differences were likely to have been due to the near-bed hydrodynamic effects of P. elegans tubes creating local sediment stabilisation. The ecological implications of differential recruitment following small-scale disturbances within patches compared to outside patches are discussed. The ability of P. elegans patches to enhance successful conspecific colonisation, as demonstrated here, may explain the longevity of such patches. Their persistence promotes alpha diversity and small-scale patchiness, together with providing a local source of colonists for the initial recovery of large-scale disturbances.     

Rock selection for nesting inProformica longiseta Collingwood, 1978 (Hymenoptera,Formicidae) in a Mediterranean high mountain

Proformica longiseta, an ant species endemic to certain high mountains, has been studied with regard to its tendency to nest underneath rocks. This behaviour led us to investigate whether a particular type of rock is selected, and, if so, the advantages to this species of the selection. This study was located at 2400 m above sea-level in the Sierra Nevada mountains (Granada, Spain). To determine the range of rock sizes available, in eight control plots the thicknesses were recorded and also the maximum and minimum diameters of all rocks with surface area of more than 6 cm². A total of 1724 rocks were recorded, noting among the rock types available those that were used for nesting. Also as a preliminary estimate of the thermal characteristics of the rocks, we recorded the temperatures of the air, soil surface, soil under a rock covering an ant nest, and soil at 30 cm depth. The results indicate thatP. longiseta selects flat rocks with a surface area/thickness ratio of 2–5, the thickness being not less than 1.5 cm, the surface area being 50–250 cm² and volume less than 1000 cm³. This type of rock offers the nests two beneficial but apparently contradictory effects: (1) protection against high temperatures on hot days, and (2) warmth on colder days by absorbing the diffusing solar heat more effectively than the air or soil around the nest.     

Host range ofPachycerus cordiger (=P. Scabrosus) (Col.: Curculionidae)

The univoltine weevilPachycerus cordiger Germar (=P. scabrosus Brullé) completes its life cycle on species of Boraginaceae, it is found from western Europe to the Middle East. In southern France, adultP. cordiger were collected feeding on the leaves ofHeliotropium europaeum L.,Echium vulgare L. andCynoglossum creticum Miller, whereas larvae were found feeding externally on the roots of the three plant species from within an earthen cell. BecauseP. cordiger is considered too much of a generalist to be released in Australia, work on the weevil as a potential biological control agent ofH. europaeum has been stopped.     

Characterization of Prorocentrum elegans and Prorocentrum levis (Dinophyceae) from the southeastern Bay of Biscay by morphology and molecular phylogeny

Benthic Prorocentrum species can produce toxins that adversely affect animals and human health. They are known to co‐occur with other bloom‐forming, potentially toxic, benthic dinoflagellates of the genera Ostreopsis, Coolia, and Gambierdiscus. In this study, we report on the presence of P. elegans M.Faust and P. levis M.A.Faust, Kibler, Vandersea, P.A. Tester & Litaker from the southeastern Bay of Biscay. Sampling was carried out in the Summer‐Autumn 2010–2012 along the Atlantic coast of the Iberian Peninsula, but these two species were only found in the northeastern part of the Peninsula. Strains were isolated from macroalgae collected from rocky‐shore areas bordering accessible beaches. Morphological traits of isolated strains were analyzed by LM and SEM, whereas molecular analyses were performed using the LSU and internal transcribed spacer (ITS)1‐5.8S‐ITS2 regions of the rDNA. A bioassay with Artemia fransciscana and liquid chromatography–high‐resolution mass spectrometry analyses were used to check the toxicity of the species, whose results were negative. The strains mostly corresponded to their species original morphological characterization, which is supported by the phylogenetic analyses in the case of P. levis, whereas for P. elegans, this is the first known molecular characterization. This is also the second known report of P. elegans.     

Quantitative distribution of meiobenthos and the structure of the free-living nematode community of the mangrove intertidal zone in Nha Trang bay (Vietnam) in the South China Sea

Meiobenthic studies were performed in an intertidal area in the Be River estuary (Nha Trang Bay, Vietnam). The study area is an area of riverine-type mangroves that have been heavily damaged by human impacts, including timber cutting and waste. Three biotopes are situated in the middle intertidal zone: a fringe of Rhizophora stylosa, a bush area composed of Avicennia aff. alba behind it, and muddy sand with fiddler crabs (Uca spp.), which is free of mangrove plants. Three replicate samples of meiobenthos were collected in each biotope and each sample was subdivided into two layers: 0–1 and 1–4 cm. The abundance of metazoan meiobenthos varied from 735 specimens/10 cm² in the Uca spp. biotope to 244 specimens/10 cm² beneath the Rhizophora trees. Six taxonomic groups of high rank were found among the meiofauna: Nematoda, Copepoda (Harpacticoida), Oligochaeta, Turbellaria, Kinorhyncha, and Foraminifera (Allogromiida). The spatial variability of meiobenthos and its key taxa was estimated and the spatial distribution patterns of free-living nematode species were described. About 90% of the total meiobenthos inhabited the upper 0–1 cm of the sediments. Nematodes constituted 90–95% of all meiobenthic organisms in the samples. A total of 48 species of free-living nematodes were found in the investigated mangrove intertidal area. In terms of species composition and set of dominants, the nematode community is comprised of three local assemblages: one of them inhabits the uppermost centimeter in the Uca and Avicennia biocenoses; the second assemblage occupies the upper sediment layer in the Rhizophora stand; a less abundant but specific assemblage of several nematode species occurs in the subsurface sediments at all three sites.     

Yeast communities of the cactusPilosocereus arrabidae as resources for larval and adult stages ofDrosophila serido

The feeding behavior ofDrosophila serido on the yeast communities of necrotic stem tissue ofPilosocereus arrabidae were studied in a sand dune ecosystem of Rio de Janeiro, Brazil. The prevalence of cactophilic yeasts includingPichia barkeri, Candida sonorensis andGeotrichum sp. in the crops and external surfaces ofD. serido reflected its association with the cactus habitat. The effective number of yeasts vectored on the surface of flies was higher than that in the crops. Also overlap between the yeasts from stems and from crops was partial suggesting selective feeding by the flies in the substrates visited. The females had a higher effective number of yeast species and a lower similarity than males with the yeast community ofP. arrabidae. This was probably related to the search for oviposition sites by females. The presence ofPichia thermotolerans-like andPichia amethionina varpachycereana in the flies, but not inP. arrabidae stems, indicated thatD. serido was not limited to this cactus species. The larvae and adults lived in different patches with the adults feeding in patches with higher yeast species richness. The larvae had a narrower feeding niche and higher overlap withP. arrabidae, and preferredP. barkeri andPichia cactophila as food. Adult flies fed on patches with the most frequent yeasts except forP. cactophila. Pichia caribaea was found in higher frequency in the adult crops than in the stems. Our data suggested that there was food selection and diet partitioning between adult and larval stages ofD. serido.     

The process of population increase and patterns of resource utilization of two spider mites,Oligonychus ununguis (Jacobi) andPanonychus citri (McGregor), under experimental conditions (Acari: Tetranychidae)

Summary Pattern of population growth and characteristics of habitat utilization and of migration by two species of spider mites were studied under experimental conditions. The population growth ofOligonychus ununguis (Jacobi) on a chestnut occurred only on a single mite-release leaf over a long period, and few individuals moved away. Most of the 2nd progeny generation females of this species emigrated from the mite-release leaf as well as the sapling by means of ballooning threads. During this growth period, population density on the mite-release leaf levelled off, whereas that on the sapling increased. In contrast, the foundress ofPanonychus citri (McGregor) on citrus actively moved over several neighbouring leaves, and until the 2nd progeny generation females emerged, individuals were distributed over all the sapling leaves by means of walking. Emigration from the sapling was not observed until the 2nd progeny females emerged, and after that the mites emigrated by means of ballooning threads. The population density ofP. citri on the sapling levelled off and was rather decreased on the mite-release leaf at the time of mite emigration. Comparing the changing pattern of the relative degree of aggregation (m ^*/m) measured in two different units between these two species, the pattern ofm ^*/m in 1 cm² on the mite release leaf inO. ununguis resembled that of the unit of leaves on the sapling inP. citri. This result as well as behavioural observations indicate that migration ofO. ununguis is the movement from leaf to leaf and that ofP. citri from sapling to sapling. It is, therefore, concluded that the boundary of the microhabitat is a single leaf forO. ununguis but sapling or foliage forP. citri. This work was presented in Annual Meeting of Jap. Soc. Appl. Ent. Zool., 1981 in Okayama.     

Vertical distribution and ecological significance of chaetognaths in the Arctic environment of Baffin Bay

Summary The vertical distributions of species of chaetognaths are described to a depth of 1043 m in Baffin Bay during the summer. The dominant species in the southern region of the Bay were Eukrohnia hamata and Sagitta maxima and, in the northern region, E. hamata and S. elegans. The younger stages of all chaetognath species were found at depths above the older more mature stages. There was no evidence of any diurnal vertical migration by any species. The population structure of E. hamata was bimodal suggesting two sub-populations and a two year life cycle. Sagitta maxima showed a multimodal population suggesting a life cycle of four or more years. The population structure of E. elegans was unimodal. Gut contents showed that E. hamata fed at a higher rate than did S. maxima. E. hamata fed at a higher rate during the night but there was no significant difference between day/night feeding rates for S. maxima. It was estimated that E. hamata consumed up to 1.8 prey items day^-1 and S. maxima 0.5 prey items day^-1. The daily ration was influenced by the water temperature. Calculations showed chaetognaths are major predators on copepods consuming between 1.2 and 1.3% of the standing crop of copepods per day. Generally the maximum concentration of chaetognaths was found at a depth below the maximum concentration of copepods.     

Effects of the deposit-feeding benthic bivalve Macoma balthica on meiobenthos

To evaluate the effects of a deposit-feeding bivalve on meiobenthic assemblage structure in muddy habitats, a laboratory experiment was performed at the Askö Laboratory in the northwestern Baltic proper. Microcosms, surface area 104 cm², containing a c. 7-cm thick layer of sieved (0.5 mm) sublittoral mud were established in June 1990. Two months later the tellinid bivalve Macoma balthica was added in quantities varying from 0 to 40 individuals per microcosm. After 5 months the effects of the bivalves on the meiofauna were surprisingly small. The density of harpacticoid copepods was lowest (P <0.05) in microcosms containing a high density of M. balthica. It is suggested that competition for food resources was responsible for this pattern. For all other meiofaunal groups, including nematodes which were the most abundant taxon (99%), no significant differences (P>0.05) were observed among treatments. The assemblage structure of the nematodes was similar between treatments. The vertical distribution of both major taxa and nematode species appeared to be unaffected by the presence of the bivalve.     

Reproduction and larval development ofManayunkia aestuarina (Bourne, 1883) (Polychaeta,Sabellidae) in a coastal region of the southern Baltic

The reproduction and larval development ofManayunkia aestuarina, a polychaete typical of brackish lenitic waters, was studied in a tideless shallow region on the south Baltic coast in 1990. Reaching abundances of up to 50 000 ind./m², it is an important element of the benthic community in this area. Reproduction started in late March/early April, when the females deposited their eggs in the tubes. On the average, 4 (maximum: 16) developing embryos were found in a maternal tube during the reproduction period. The females probably produced a mean of about 12 eggs. Development in the maternal tube lasted about 8 weeks. The first juveniles were found outside the tubes in mid-May. The survival rate during the first few weeks was estimated to be 15–20%. After reproducing, the adult animals survived until October. The changes involved in the development from eggs to juvenile animals are illustrated by drawings.     

Application of soft X-ray microradiography to observation of cystoliths in the leaves of various higher plants

Soft X-ray microradiography was applied to observation of the cystoliths, calcified bodies of higher plants, in the leaves ofMorus bombycis, Humulus scandens, Ficus elastica, F. retusa (Moraceae),Boehmeria platanifolia, Pilea viridissima (Urticaceae) andMomordica charantia (Cucurbitaceae). It was proved that this technique is useful for examination of the shape, size, distribution and number of cystoliths in fresh leaves. The microradiographs revealed large cigar-shaped cystoliths in the leaf ofP. viridissima, and neighbor-cystoliths in somewhat restricted areas of the leaves ofM. bombycis andH. scandens, and two to seven radially arranged cystoliths in the leaf ofM. charantia. The number of cystoliths per unit area of leaf (nos./cm²) was estimated to be from 1,090 to 3,900 by means of the microradiographs, varying from species to species. The CaCO₃ content of the leaf calculated from the volume and number of cystoliths was approximately 0.4 mg/cm² in all species exceptF. retusa. InF. retusa, it was about 1.06 mg/cm², the highest value among all species tested. Hand-sections of the leaves showed that the lithocysts were localized in the upper and/or lower epidermis, and they were associated with many photosynthetic cells in all species, suggesting some relationship between CaCO₃ deposition in cystoliths and photosynthesis. This paper is dedicated to Professor Kurazo Furuya, Department of Biology, Tokyo Gakugei University, on the occasion of his retirement (1986).     

Biology of the threespine stickleback,Gasterosteus aculeatus,and the blackspotted stickleback,G. wheatlandi,during their marine pelagic phase in the Bay of Fundy,Canada

Synopsis Two species ofGasterosteus were collected from the surface waters of 48 stations in the Bay of Fundy from 1979–1982. Densities varied widely according to locality and time of year (range: 1 fish 0.2 m^–2 to 1 fish 26.3 m^–2 of sea surface) but peaked within 30 km of the New Brunswick/Maine coast in July and August. A few adults were caught as far as 100 km from the coast in winter. Guts ofG. wheatlandi were significantly fuller (63.3 ± 0.6%) than those ofG. aculeatus (44.6 ± 0.1%) but there were no differences between male and female guts within species. Quantitatively, gut contents were very similar between species, consisting primarily of (99.4%): calanoid copepods (Centropages typicus Kroyer andEurytemora cfamericana Williams), copepod nauplii, cladocerans (Podon leuckarti Sars andP. polyphemoides Leuckart) and planktonic eggs (in decreasing order of importance).Gasterosteus wheatlandi ate significantly more calanoids thanG. aculeatus but all other prey types were eaten in similar amounts. Within species, there were no differences in the numbers of each prey type eaten over time. The most abundant calanoid species caught alongside the fishes in the sampling nets did not occur in the sticklebacks' diets; probably they were too large to be ingested.Gasterosteus aculeatus bred in inshore, brackish water ponds in late April. By late July most juveniles had migrated out into the Bay but a few remained until early September.Gasterosteus wheatlandi bred later in the brackish water ponds (late May) and juveniles began migrating into the Bay in early August; a few remained in the ponds until early September. Adults were found in the Bay alongside juveniles suggesting that individuals of both species may survive for a second year. In both species, growth rates of juveniles were greater in brackish water than in the sea.     

Secondary Production of Macrobenthic Invertebrates from Delaware Bay and Coastal Waters

Secondary production of benthic invertebrates was estimated for Delaware Bay and coastal Delaware. Production and turnover ratios were highest in Delaware Bay (P = 46,572 mg AFDW m⁻² yr⁻¹, P:B = 6,O) and progressively lower at two coastal stations (P = 7,501 to 30,124 mg AFDW m⁻² yr⁻¹, P:B = 2.3 to 5.3, and P = 4,485 to 4,492mg AFDW m⁻² yr⁻¹, P:B =2.3 to 4.8). Production was inversely related to sediment particle size. Production in Delaware Bay was relatively evenly distributed between deposit feeding polychaetes and suspension feeding molluscs with a definite shift in production dominance to suspension feeding molluscs at the coastal stations. Moreover, crustaceans and echinoderms played a larger role in production at the coastal stations than in Delaware Bay. Concerns about the health of soft-bottom communities in Delaware Bay expressed earlier were not supported here. Finally, it was concluded that P and P: B from the Delaware Bay area were very similar to those obtained from other areas in the North Atlantic which agrees with estimates for other estuaries in the northern hemisphere.     

Feeding habits of the Alaska greenlingHexagrammos octogrammus in the coastal waters of amurskii bay (sea of Japan)

Feeding habits of the Alaska greenlingHexagrammos octogrammus were studied in the coastal waters of Amurskii Bay in April–October 1997–1998. The greenling is characterized by a wide feeding spectrum of no less then 56 fish and invertebrate species. Decapods predominate in the diets of all fish age groups. The feeding spectrum ofH. octogrammus broadens as the fish grows. From spring to autumn, the stomach filling index of first-year fish rises, while that of the other age groups decreases, reaching minimum values in the spawning period.