Search

The population and biological characteristics of the bivalve mollusk Macoma calcarea (Gmelin, 1791) off the Novaya Zemlya Archipelago, eastern Barents Sea, are considered. The biomass of Macoma clams in the study area varied from 3.9 to 350.6 g/m2; the population density varied from 13.3 to 196.6 ind./m2. It was shown that the biomass and population density of clams do not depend on the depth and near-bottom water temperature; the size structures and growth rates were similar at different depths. The life span was found to differ significantly between clams that lived at depths shallower than 100 m (17 years) and deeper (26 years). At depths shallower than 100 m, aggregations of this species consisted mainly of juveniles (up to 4 mm); at the stations with greater depths, both juveniles and individuals with a shell length of 14.9 mm were found in abundance. Individuals of M. calcarea reach sexual maturity at an age of 3–4 yr, with a shell length of over 7.5 mm. At the stations with greater depths, there were significantly more mature clams than immature ones, and more males than females. Three stages of gametogenesis were identified in the examined females. The size of mature, ready to be spawned oocytes was 175 μm.

Structure, quantitative indicators, distribution features and main communities of macrobenthos of Malokurilskaya Bay (Shikotan Island) are described. Four taxa defined the total biomass of macrozoobenthos: polychaetes, bivalves, decapods, and gastropods. The main regularities of the distribution of macrozoobenthos are given. Four bottom communities are marked: native communities of Chaetozone setosa + Macoma nipponica, Macoma nipponica + Liocyma fluctuosa, Pagurus ochotensis, and the community of the inner aquatic area of the port of Capitella capitata + Chaetozone setosa. Suspension / filter feeders, deposit feeders and detritus feeders dominate in the trophic structure of macrozoobenthos. The trophic community “suspension / filter feeders + detritus feeders” occupies the central and southern parts of the aquatic area on the fine-grained sands. The trophic community “deposit feeders + detritus feeders” is marked on the silts of the eastern part and on the fine-grained sands of the western part of the Bay. The trophic community “scavengers / detritus feeders / browsing + suspension / filter feeders” is localized at the exit of the Bay on medium-grained sands. Anthropogenic influence is the main factor affecting the distribution and abundance of macrozoobenthos.

Organic-rich sediments in estuaries and the coastal ocean are often a product of land clearing, runoff of excess nutrients and other human activities. They can harbor pollutants, oxygen-consuming microbes and toxic hydrogen sulfide (H2S), thereby creating a hostile environment for infauna. In one barrier island lagoon, the Indian River Lagoon (IRL), Florida, layers of organic-rich sediments have increased substantially in thickness and areal extent over the past 60 years. Geochemical properties of these muddy sediments have been described; however, less is known about their habitability. We analyzed infauna and geochemical properties of 102 samples taken during wet and dry seasons at 17 locations spanning 60 km of the lagoon. We quantified infaunal abundance and diversity (Shannon-Wiener, H′) and determined Pearson’s correlation coefficients for effective number of species (ENS = eH′) vs. sediment porosity (ϕ = 0.69–0.95), organic carbon (1–8%), nitrogen (0.1–0.7%), silt + clay (16–99%), porewater H2S (5–3,600 μM), and other environmental variables. Small bivalves accounted for 70% of the organisms collected, followed by gastropods, polychaetes and other biota. The bivalves were predominantly Macoma spp., Mulinia lateralis and Parastarte triquetra with average abundances of 3,896, 2,049, and 926 individuals per m2, respectively. High abundance of some species, such as Macoma, showed that these opportunists had adapted to poor quality sediments. More than two-thirds of the 35 species collected were present at 2 of sediment. Cluster analysis identified four groups of stations with significantly different geochemical properties. Permutation analyses of variance indicated that the four groups also represented statistically different infaunal communities. Diversity decreased with increasing sediment concentrations of organic carbon, nitrogen and silt + clay; however, community richness at our most prolific station along the perimeter of muddy deposits was ∼7 times lower than found previously in sandy sediments from the IRL. The results identified areas where infaunal communities have experienced the greatest stress due to accumulation of organic-rich sediments. Results from this study help support management plans for remediation of organic-rich mud and improvement of sediment and water quality, especially in areas identified with low ENS.

Nielsen, Jan Kresten (2021): Macoma Leach, 1819 (Mollusca: Bivalvia: Tellinidae): the unavailability of Limecola Brown, 1844, and Limicola Leach, 1852. Zootaxa 5052 (4): 579-584, DOI: https://doi.org/10.11646/zootaxa.5052.4.7

Author(s): Groves, Lindsey T.; Squires, Richard L. | Abstract: This checklist is a sequel to the one published by A. Myra Keen and Herdis Bentson in 1944 and is an alphabetical listing of California marine Paleogene–Neogene mollusk species or subspecies described and/or figured in the published literature spanning the interval of 1944 through 2020. The original data are given for each species and subspecies of bivalves, gastropods, chitons (polyplacophorans), scaphopods, and cephalopods. Where detected, formation names, ages, taxonomy, systematics, and specimen disposition were corrected. A total of 559 genera and 1,698 species/subspecies were tabulated, with the bivalves and gastropods being the most abundant taxa. Bivalve and gastropod diversity steadily built up during the Paleocene, nearly doubled during the Eocene warm time, declined greatly during the cool time of the Oligocene, rebounded to its highest peak in the Miocene and then declined slightly during the Pliocene. The other classes represented only minor faunal components. Chitons were only reported from the Pliocene, and cephalopods had their highest diversity during the Paleocene and Eocene. Bivalve genera having the highest diversity are: Glycymeris, Macoma, Mactromeris, Nuculana, and Tellina. Gastropod genera having the highest diversity are Cancellaria and Turritella. It is very likely that the Turritella species/subspecies complex has been significantly overnamed. The high point of research productivity of published reports on California Paleogene-Neogene mollusks was in 1990–1994, and a significant decline occurred in 1995–1996, following the closure of the Menlo Park USGS Paleontology and Stratigraphy facility. An overall decline in productivity has continued, with noticeable upticks in 2003 and in recent years.

For a better understanding of functioning and stability of ecosystems, it is important to know to what extent constituent species show similarity in their long-term fluctuation patterns, i.e. whether their numbers and biomass frequently show simultaneous peaks and lows. Synchronic peaks and lows of important species would enhance variability in the functioning of the entire system and might affect its stability. When fluctuation patterns of individual species are largely independent, their peaks and lows would tend to extinguish each other’s effect on overall parameters (such as total zoobenthic biomass), thus promoting system stability. A long-term (46 years) monitoring study of the macrozoobenthos in a large (50 km2) tidal-flat area revealed that the 4 most important bivalve species (3 suspension feeders: Cerastoderma edule, Mytilus edulis, Mya arenaria and 1 deposit/suspension feeder: Limecola (Macoma) balthica) frequently showed peak numbers of their recruits in the same years. The annual growth rates of the three suspension feeding species showed some synchrony as well. Annual survival rates, on the other hand, did not show any synchronization, wiping out the initial synchrony of numbers within less than 2 years. As a result, annual biomass values did not show any positive between-species correlations. Annual amounts of bivalves that are accessible as bird food rarely declined to levels below 5 g AFDW m−2 and showed limited (5 to 10 fold difference between maximal and minimal values) variation. Oystercatchers left the area quicker in late winter and showed increased death rates at very low levels of food supply. Total bivalve bird food did not show any significant long-term trend. However, biomass of Mya arenaria showed an increasing trend and that of Limecola balthica a declining trend.

Benthic invertebrates are a crucial trophic link in Arctic marine food webs. However, estimates of the contribution of different primary production sources sustaining these organisms are not well characterised. We measured the stable carbon isotope values (δ13C) of essential amino acids (EAAs) in muscle tissue from two common bivalve genera (Macoma spp. and Astarte spp.) collected in Hanna Shoal in the northeastern Chukchi Sea. Mixing models comparing the δ13CEAA fingerprints of the bivalves to a suite of primary production endmembers revealed relatively high contributions of EAAs from phytoplankton and bacteria in both species. We also examined whether δ13CEAA fingerprints could be produced from the EAAs preserved in bivalve shells, which could allow primary production sources to be estimated from ancient bivalve shells. The δ13CEAA fingerprints from a suite of paired modern bivalve shells and muscle from Macoma calcarea from across the Chukchi Sea revealed a correspondence between the estimates of the dominant primary production source of EAAs derived from analyses of these two tissue types. Our findings indicate that δ13CEAA fingerprinting of marine bivalves can be used to examine dominant organic matter sources in the Arctic marine benthos in recent years as well as in deeper time.

Changes in species composition and biomass of Arctic benthic communities are predicted to occur in response to environmental changes associated with oceanic warming and sea-ice loss. Such changes will likely impact ecosystem function, including flows of energy and organic material through the Arctic marine food web. Oxygen consumption rates can be used to quantify differences in metabolic demand among species and estimate the effects of shifting community structure on benthic carbon consumption. Closed-system respirometry using non-invasive oxygen optodes was conducted onboard the R/V Sikuliaq in June 2017 and 2018 on six dominant species of benthic macrofauna from the northern Bering and southern Chukchi Sea shelves, including five bivalve species (Macoma sp., Serripes groenlandicus, Astarte sp., Hiatella arctica and Nuculana pernula) and one amphipod species (Ampelisca macrocephala). Results revealed species-specific respiration rates with high metabolic demand for S. groenlandicus and A. macrocephala compared to that of the other species. For a hypothetical 0.1-g ash-free dry mass individual, the standard metabolic rate of S. groenlandicus would be 4.3 times higher than that of Astarte sp. Overall, carbon demand ranged from 8 to 475 μg C individual−1 day−1 for the species and sizes of individuals measured. The allometric scaling of respiration rate with biomass also varied among species. The scaling coefficient was similar for H. arctica, A. macrocephala and Astarte sp., while it was high for S. groenlandicus and low for Macoma sp. These results suggest that observed shifts in spatial distribution of the dominant macrofaunal taxa across this region will impact carbon demand of the benthic community. Hence, ecosystem models seeking to incorporate benthic system functionality may need to differentiate between communities that exhibit different oxygen demands.

Microphytobenthos forms an important part of the diet of macrofauna (macrozoobenthos) in many intertidal ecosystems. It is unclear, however, whether the dependence of macrofauna on microphytobenthos varies spatially within and among tidal systems. We aim (1) to assess the spatial variability in the importance of microphytobenthos in the diet of macrofauna (i.e., between and within two tidal basins and as function of elevation), (2) to quantify grazing pressure of the macrofaunal community on different potential food sources (microphytobenthos, phytoplankton and terrestrial organic material) for several sites in two tidal basins and (3) to compare microphytobenthic production and summer/autumn grazing of the total macrofaunal community and grazing pressure per feeding type, with potential microphytobenthic production estimated from rates in early spring, when grazing was low. Using a natural stable isotope approach, we identified microphytobenthos as a more important food source for macrofauna than phytoplankton and terrestrial organic material. Microphytobenthos dependency differed between tidal basins for the genera Bathyporeia (sand digger shrimp), Macoma (Baltic tellin), and Peringia (mudsnail) and for sampled individuals of all genera combined, and did not vary as function of elevation. We showed that macrofaunal grazing on microphytobenthos is quantitatively important and, in some cases, approached microphytobenthic production rates in early spring. No positive relation between microphytobenthic production in early spring and macrofaunal grazing in summer/autumn was observed. This suggests that the studied consumer‐resource interactions are coupled on a larger spatial scale (i.e., mesoscale, ≈10 to 100 km), rather than the fine (mm to m) scale.

The Velikaya Salma Strait is part of a fiard, typical of the Kandalaksha Gulf of the White Sea. Seabed topography, landscapes, and bottom sediments were studied in an area of 35.12 km2 (depths of 10–120 m) using geophysical methods, geological sampling, and visual observations. Macrobenthos distribution was sampled at 15–60 m depth and studied using an underwater camera. Structural-denudation, glacial, gravity, and tidal current landforms were identified on the Strait seabed. Bottom sediments vary from boulder–pebble to pelite. The bathymetric zonation of their distribution is disturbed when tidal currents encounter the dissected seabed topography and by gravitational displacements. Macrobenthos distribution has statistically significant dependence on bottom sediments grain size and depths. Galathowenia oculata–Chaetozone setosa community prevails on muddy sediment, and Macoma calcarea–Scoloplos acutus community prevails on sandy bottom. Statistical relationships between sidescan sonar images and macrobenthos distribution are stable in the areas of gently dismembered seabed and are lost in the areas of dissected topography.

We conducted a comparative analysis of the fatty acid (FA) composition and the ratios of stable isotopes of carbon (δ13C) and nitrogen (δ15N) in soft tissues of ten species of bivalve mollusks collected simultaneously on adjacent biotopes in shallow Vostok Bay (the Sea of Japan). Comparison of the FA composition of the lipids of digestive gland and all soft tissues showed that the percentages of C16 and C18 marker FAs were greater in the digestive gland and the levels of marker C20 and C22 FAs were, in most cases, higher in soft tissues. According to the results of cluster analysis and principal component analysis, four groups of samples were identified with a similarity of the FA composition of more than 80% within groups. The carbon stableisotope ratios varied within very wide limits in the studied species of bivalves; the range of δ13C variations was 8.1‰. The range of δ15N variations was much smaller, 2.5‰. Two pairs of species of mollusks (Saxidomus purpurata–Protothaca euglypta and P. jedoensis–Diplodonta semiasperoides) did not differ in the values of both δ15N and δ13C, the remaining species differed in at least one of these parameters. The greatest similarity of the FA composition and stable-isotope ratios was found in species that inhabit similar substrates, except Macoma irus and D. semiasperoides. Particularly marked differences in the FA composition and stable-isotope ratios were found between a filter-/surface deposit-feeder M. irus and filter-feeders Arca boucardi and Mytilus coruscus that live next to this species.

Pristine and before-disturbance baseline data are essential tools in monitoring and measurement of progress and net success or otherwise of restoration of degraded ecosystems. These are usually lacking in regions such as the Niger Delta where demands for such data is pressing due to impending pollution. We present a rare case of available pre-spill data of how distribution and abundance of macrobenthic infauna were structured by some physical and chemical variables of interstitial water in Bodo Creek, lower eastern Niger Delta, Nigeria, before two major oil spills impacted the creek in 2008. Monthly composite samples of macrobenthos and interstitial water in four soft-bottom unvegetated intertidal flats were analysed for one year. Thirty six taxa, twenty-two families and four classes of macrozoobenthos were recorded. The bivalves Lorepis aberrans, Macoma innominata, Senilia senilis, and polychaetes Nereis diversicolor, N. virens, N. pelagic and Clymenella torquata were eurizonal in distribution and abundant, attaining sub-dominant and dominant status at the sites. The observed pattern of reduction in rainy season macrofauna abundance in some river systems of the Niger Delta due to sediment instability was counterbalanced by increased recruitment of the dominant taxa. Canonical Correspondence Analysis (CCA) showed the explanatory (physicochemical) variables only accounted for 31.8% of variation in the species data. The species–environmental correlations were: 0.64, 0.74 and 0.72 for the first, second and third axes, respectively. Plans for cleanup, remediation and ‘restoration’ of Bodo Creek, have reached implementation stage as the Federal Government of Nigeria flagged off cleanup of Ogoniland on June 2, 2016. The usefulness of these data as potential template for monitoring and evaluation of water quality response to the proposed cleanup and restoration is highlighted.

The northeastern Chukchi Sea is a shallow subarctic shelf ecosystem that supports a substantial benthic infaunal community of which bivalves are a major component. We assessed the patterns in population abundance, biomass, and caloric content of ten dominant bivalve taxa in relation to the distribution of the upper trophic level consumer Pacific walrus (Odobenus rosmarus divergens). Bivalves were collected over four cruises in the northeastern Chukchi Sea (2009, 2010, 2012, 2013). Our samples were largely dominated by calorie-dense, deposit-feeding species, including Macoma spp., Ennucula tenuis, Nuculana spp. and Yoldia spp. Weight-frequency distributions were strongly right-skewed for most taxa, though some showed evidence of a bimodal distribution. Caloric densities as measured through bomb calorimetry significantly differed among taxa (ANOVA F = 32.57, df = 9, p-value

Cyanobacterial blooms have been increasing worldwide due to increased nutrients associated with urban, industrial, and agricultural development. Blooms that occur in the Indian River Lagoon (IRL), Florida may be increased by nutrient-laden runoff from storm water and non-point sewage pollution due to alterations to the watershed. In the IRL, during the summer of 2006, extensive blooms of the marine cyanobacterium, Lyngbya majuscula, were observed forming mats throughout beds of the seagrass Halodule wrightii in Fort Pierce, Florida. The effects of cyanobacterial blooms were compared to artificial shading of H. wrightii to assess the shading potential of L. majuscula. The combined effects of L. majuscula removal and artificial shading showed increases in the below ground biomass of H. wrightii. However, leaf length increased in the presence of L. majuscula. In response to artificial shading, H. wrightii decreased in density, but showed similar leaf elongation. A common bivalve in our study area, Macoma constricta, increased in density when L. majuscula was removed. Therefore, when L. majuscula blooms occur, light limitation is one of the mechanisms altering H. wrightii density and leaf lengths in the IRL. Loss of H. wrightii biomass due to shading from cyanobacterial mats may further damage the diversity and habitat value of the IRL.

We evaluated the prevalence of influenza A virus (IAV) in different species of bivalves inhabiting natural water bodies in waterfowl habitat along the Delmarva Peninsula and Chesapeake Bay in eastern Maryland. Bivalve tissue from clam and mussel specimens (Macoma balthica, Macoma phenax, Mulinia sp., Rangia cuneata, Mya arenaria, Guekensia demissa, and an undetermined mussel species) from five collection sites was analyzed for the presence of type A influenza virus by qPCR targeting the matrix gene. Of the 300 tissue samples analyzed, 13 samples (4.3%) tested positive for presence of influenza virus A matrix gene. To our knowledge, this is the first report of detection of IAV in the tissue of any bivalve mollusk from a natural water body.

The relative influence of consumers (top down) and resources (bottom up) on the distribution and abundance of organisms remains a key question in ecology. We examined the relationships between consumer and resource variables along a productivity gradient for a dominant predator–prey interaction in a marine soft‐sediment system. We 1) quantified density and size of the clam Macoma balthica (prey species) in six replicate sites at each of four habitat types (shallow mud, deep mud, muddy sand and detrital mud) in the Rhode River, Chesapeake Bay. We selected one habitat type of high food availability and clam density (shallow mud) and another of low food availability and clam density (muddy sand) for manipulative experiments. Then, we 2) measured M. balthica survival and growth through transplants, 3) measured food availability as sedimentary organic carbon content, 4) quantified predator density, and 5) calculated predator foraging efficiency in the two habitat types. Clam density in the four habitat types differed and was related to sedimentary carbon availability and predator density. One of the habitats, detrital mud, appeared to be a population sink because it only held juvenile Macoma that never survived to reproductive age. Macoma size and growth, and predator (mainly blue crab Callinectes sapidus) densities were positively correlated with productivity and were higher in shallow mud than muddy sand. In contrast, Macoma mortality, local ‘interaction strength’, and predator foraging efficiency were lower in the productive habitat (shallow mud). Thus, predation intensity was inversely correlated with productivity (food availability); consumer and resource effects differed by habitat type; and, at a relatively small spatial scale, consumer and resource forces jointly determined population dynamics in this soft‐sediment marine system.

A laboratory microcosm experiment was performed to study the effect of bivalves on meiobenthic and nematode community structures. Three bivalve species dominant in shallow coastal sediments of the southern Baltic Sea differing in terms of feeding mode, faecal deposition and sediment depth penetration (Macoma balthica, Cerastoderma glaucum and Mya arenaria) were selected as model organisms: our experiment demonstrated that although the bivalves had no overall effect on total meiobenthic densities, they variously affected a number of meiobenthic major taxa. Species buried under the sediment surface (M. balthica, M. arenaria) facilitated meiobenthos to penetrate deeper sediment layers compared to the surface-dwelling bivalves (C. glaucum). The most conspicuous response of meiobenthos and nematodes to bivalve activities was, however, observed at the sediment surface: densities of juvenile bivalves and rotifers, and the dominant nematode species (Adoncholaimus thalassophygas, Desmolaimus cf. zeelandicus and Halomonhystera disjuncta) were significantly reduced in surface sediments in Macoma microcosms compared to other treatments. It is suggested that different bivalve feeding modes (deposit-feeding vs. suspension-feeding), attributes of faecal deposition (to the sediment surface vs. to subsurface sediments) and depth of sediment penetration can significantly change meiobenthic and nematode communities in sandy sediments.

The elevated occurrence of hydrophobic organic chemicals (HOCs) such as polycyclic aromatic hydrocarbons (PAH), polychlorinated biphenyls (PCBs) and legacy organchlorine pesticides (e.g. chlordane and DDT) in estuarine sediments continues to poses challenges for maintaining the health of aquatic ecosystems. Current efforts to develop and apply protective, science-based sediment quality regulations for impaired waterbodies are hampered by non-concordance between model predictions and measured bioaccumulation and toxicity. A passive sampler incorporating commercially available solid phase microextraction (SPME) fibers was employed in lab and field studies to measure the freely dissolved concentration of target HOCs (Cfree) and determine its suitability as a proxy for bioaccumulation. SPME deduced Cfree for organochlorines was highly correlated with tissue concentrations (Cb) of Macoma and Nereis spp. co-exposed in laboratory microcosms containing both spiked and naturally contaminated sediments. This positive association was also observed in situ for endemic bivalves, where SPME samplers were deployed for up to 1 month at an estuarine field site. The concordance between Cb and Cfree for PAH was more variable, in part due to likely biotransformation by model invertebrates. These results indicate that SPME passive samplers can serve as a proxy for bioaccumulation of sediment-associated organochlorines in both lab and field studies, reducing the uncertainty associated with model predictions that do not adequately account for differential bioavailability.

Secondary production of macrobenthic communities is evaluated for 14 different-type estuaries in Primorye on the base of 52 surveys conducted in 2007-2013 (922 stations, 2426 samples). Species composition and abundance of macrobenthos in the estuaries depend mostly on water salinity. Three types of estuaries were distinguished: i) polyhaline with prevaled salinity 18-30 ‰ (external and internal estuaries of the rivers Ryazanovka, Barabashevka, Sukhodol, Tumanovka and external estuaries of the rivers Olga and Avvakumovka); ii) mesohaline with salinity 5-18 ‰ (external and internal estuaries of the rivers Tesnaya and Gladkaya, internal estuaries of the rivers Avvakumovka, Kievka, and Partizanskaya, Lake Presnoye and external estuary of the Razdolnaya River); and iii) oligohaline with salinity 0.5-5.0 ‰ (internal estuaries of the rivers Razdolnaya, Artemovka and Lake Solenoye). Mean annual biomass of macrozoobenthos is the lowest (2.8 ± 0.4 gС/m 2 ) in the polyhaline estuaries and the highest in the meso- and oligihaline ones (6.6 ± 3.0 and 7.0 ± 2.5 gС/m 2 , respectively). Annual production of macrobenthic communities in the estuaries varies from 0.5 to 11.2 gС/m 2 , with mean values 7.5 ± 1.0 gС/m 2 in the polyhaline estuaries, 4.1 ± 1.3 gС/m 2 in the mesohaline estuaries, and 2.7 ± 1.4 gС/m 2 in the oligohaline estuaries, it is the highest in the polyhaline estuaries and the lowest in the oligohaline ones. The production is formed mainly by gastropods, bivalves, polychaetes and amphipods in the polyhaline estuaries; the same groups and also isopods and amphibiotic insects larvae form the production in the mesohaline estuaries, and bivalves and polychaetes are the main producers in the oligohaline estuaries. Daily production of macrobenthic community has strong seasonal variation with the maximum in July-September and the minimum (sometimes below zero) in May-June and October, i.e. at the beginning and the end of vegetation season. The portion of carnivore macrobenthos production varies from 0.7 to 26.5 % of the total annual production of macrobenthic community, it is the highest in the mesohaline estuaries. It increases from spring to autumn; in the autumn predators have the best feeding because of high abundance of young benthic animals at the bottom of estuaries. Mean annual P/B -ratio is 3.4, 1.1 and 0.4 for the polyhaline, mesohaline and oligohaline estuaries, respectively, that is conditioned by species composition of dominant taxonomic groups. Species composition of bivalve mollusks is the main factor of macrobenthic production variability: brackish clam Corbicula japonica with high biomass (up to 5 kg/m 2 ) and low P/B -ratio (0.4-0.7, mean value ≈ 0.5) dominates in the mesohaline and oligohaline estuaries, while euryhaline marine bivalves as Macoma spp., Potamocorbula amurensis, Laternula marilina , and others dominate in the polyhaline estuaries though their biomass is relatively low (no more than 0.36 kg/m 2 ), their P/B -ratio is 0.8-4.5. Year-to-year variability of macrozoobenthos production is supposedly significant, at least its considerable fluctuations are registered in the Sukhodol estuary (from 4.8 to 11.2 gС/m 2 in the 2009-2012). Estuarine macrobenthic communities in Primorye usually have intermediate values of production between those in freshwater and seawater biotopes.

Many size-selective predators switch their diet during ontogeny. At the White Sea, the adult moonsnails Amauropsis islandica feed mostly on Macoma balthica clams. The diet of juveniles was largely unknown. We conducted a field survey and a caging experiment to find out if juvenile moonsnails can prey on Hydrobia ulvae, and whether they prefer this snail to their usual prey. Live molluscs and their intact or perforated shells were collected from 34 sediment cores. We exposed the single-prey cages with 50 Macoma (MP) or 50 Hydrobia (HP) together with five Amauropsis juveniles, as well as the cages where both prey species were in a 25:25 proportion (HMP). While live Hydrobia was more abundant in the natural assemblages, Amauropsis preferred Macoma, as indicated by proportions of perforated shells. The caging experiment produced similar results. Per capita Macoma consumption rate was significantly higher than Hydrobia consumption rate (6.4 ± 0.5 mg day−1 ind.−1vs. 1.4±0.2 mg day−1 ind.−1 in MP and HP respectively). Prey consumption rates in the single-prey treatments were higher than in mixed-prey cages regardless of prey species. Different mechanisms explain this variation: for Hydrobia it is a consequence of the dietary shift, while for Macoma it reflects the ‘floor’ effect in HMP cages, where virtually all Macoma had been drilled by the end of exposure term. While Macoma is the preferable prey of young Amauropsis, Hydrobia can supplement the diet of juveniles when Macoma is scarce in certain locations.

An understanding of the origin and fate of organic matter deposited on the seabed in the Chukchi Sea is critical to our understanding of how regional changes in climate will affect this highly productive ecosystem. We measured the concentrations of chlorophyll a, pheopigments, and accessory pigments in sediments at 39 stations using high-performance liquid chromatography (HPLC) to investigate the degradation pathways of chlorophyll-containing organic matter. Chlorophyll a concentrations were among the highest ever reported in marine sediments (up to 665 mg m-2). Measurements of pheopigments, including pheophytin a, pheophorbide a, and pyropheophorbide a, revealed substantial degradative processing of organic matter that began ∼ 2 weeks after ice breakup. However, the ratio of chlorophyll a to total pheopigments (Chl a : pheo) was > 1 in most stations, indicating that chlorophyll a was preserved despite grazing and senescent degradation pathways that produced accumulated pheopigments. Increased δ13C values of bulk sediment organic matter was also positively correlated to concentrations of pheophytin a (p < 0.01, r=0.46), and total pheopigment concentration was correlated to the δ13C values of the epibenthic scavenging snow crab Chionoecetes opilio (p < 0.01, r = 0.92) and the surface deposit feeding bivalves Macoma spp. (p < 0.01, r = 0.69). Based on these observations, we hypothesize that organic matter degraded by microbial and herbivorous grazing pathways produces an enriched 13C signal that is transferred to macrofaunal consumers, providing a critical source of carbon to a rich and diverse benthic food web.

MIDDLE MIOCENE BIVALVES FROM THE CARPATHIAN FOREDEEP BASIN: THE BUSKO (MŁYNY) PIG-1 AND KAZIMIERZA WIELKA (DONOSY) PIG-1 BOREHOLES – STRATIGRAPHY AND TAXONOMY Abstract. The study is based on the fossil material derived from cores drilled in 2010 in the western part of the Carpathian Foredeep Basin. The deposits overlying the gypsum level, represented mainly by mudstones and clays of the Machow Fm., are less than 200m thick in this part of the Carpathian Foredeep. In total, 56 samples were investigated: 32 samples from the Busko (Mlyny) PIG-1 drilling core 200 m long; and 24 samples from the Kazimierza Wielka (Donosy) PIG-1 drilling core, 191m long. Twelve bivalve species have been identified, namely: Nucula ( Nucula ) nucleus (Linnaeus, 1758), Lentipecten corneus denudatus (Reuss, 1867), Delectopecten vitreus (Gmelin, 1791), Inaequicostata cf. politioanei (Jekelius, 1944), Obsoletiforma vindobonensis (Laskarew, 1903), Plicatiforma pseudoplicata (Friedberg, 1934), Ervilia podolica (Eichwald, 1830), Ervilia trigonula Sokolov, 1899, Abra ( Syndosmya ) reflexa (Eichwald, 1830), Macoma ( Psammacoma ) elliptica (Brocchi, 1814), Corbula ( Varicorbula ) cf. gibba (Olivi, 1792) and Cuspidaria rostrata (Spengler, 1793). Stratigraphic ranges of bivalve species as well as descriptions of rare or stratigraphically important species have been presented. The bivalves define the Badenian/Sarmatian boundary within the depth range 109.10–127.70 m in the Busko (Mlyny) PIG-1 borehole, and within the depth range 150.80–162.80 m in the Kazimierza Wielka (Donosy) PIG-1 borehole. Specifically, the scallop Delectopecten vitreus (Gmelin, 1791) defines the base of the Machow Fm. as the Late Badenian, while the species Abra ( Syndosmya ) reflexa (Eichwald, 1830) enables to specify the age of the uppermost part of the Machow Fm. as the Early Sarmatian.

Long-term (>40 yr, started in the 1970s) data series of Limecola (Macoma) balthica dynamics in 4 distant (>100 km) areas of the Dutch Wadden Sea are described and compared, including annual recruitment, total abundance, age composition (recruits/adults) and adult survival. The aim was to determine to what extent long-term changes in L. balthica population attributes were synchronous in populations throughout the Dutch Wadden Sea and to identify possible underlying causes. At all 4 sites studied, changes in annual recruitment (n m-2 of spat-sized animals in summer) was synchronous with long-term declining trends and peaks and lows occurring in the same years at all sites. Adult survival was high for the first 15 to 20 yr, but irregular after 1990 with low values for periods of varying length. In contrast to the strongly synchronized recruitment, the low-survival periods were not synchronous over the Wadden Sea. Adult density and total biomass varied in parallel over most sites and were low throughout the Dutch Wadden Sea (less than a quarter of the earlier long-term average) from 2005 onwards. The factors suggested to underlie these changes in abundance were (1) negative effects of climate warming on recruitment, which includes higher abundance of predators on young bottom stages, and (2) an unknown cause of enhanced adult mortality, possibly disease. Synchronization in recruitment, adult density and total biomass of L. balthica populations throughout the Dutch Wadden Sea indicates that they are part of a Wadden Sea-wide metapopulation.

We followed the dynamics of the population of the bivalve Limecola (Macoma) balthica in the westernmost part of the Wadden Sea by monitoring for 44 years (1973–2016) its numbers and age composition at 15 sites in a 50-km2 tidal-flat area. During the first half of this period, the annual recruitment and adult survival were at a relatively constant level, resulting in rather constant numbers. During the second half of the observation period, annual recruitment and adult survival showed declining trends, resulting in seriously reduced adult abundance. Sudden substantial reductions in adult survival started around 1996 at a few sites to spread over the entire area within 5 years, like an infectious disease. The resulting small adult stocks produced small numbers of recruits. The stock–recruitment curve showed an increasing part up to about 30 adults m−2, followed by invariably successful recruitments at > 40 adults m−2. Both recruitment and adult survival were negatively related to water temperatures. However, elevated temperatures after 1997 could not explain the very low survival rates observed after 1996 and the very low recruitment success after 2003. So far, recovery of the population has hardly taken place, with both recruitment and adult survival at lower levels than observed for the initial stable period.

Climate warming in seasonally ice-covered seas is expected to reduce the extent and duration of annual sea ice. Resulting changes in sea ice related blooms of ice algae or phytoplankton may in turn alter the timing, magnitude, or quality of organic matter inputs to the sea floor. If benthic taxa rely differently on direct consumption of settling fresh microalgae for growth and reproduction, altered blooms may lead to reorganization of deposit-feeding assemblages. To assess the potential for such changes, we examined the diets of five abundant deposit-feeders (three infaunal bivalves, a polychaete, and a brittle star) with different feeding modes over the course of the spring bloom in May–June 2007 in the north-central Bering Sea (30–90 m depth). Short-term data from gut contents reflected feeding modes, with the bivalves Macoma calcarea, Ennucula tenuis, and Nuculana radiata, and the brittle star Ophiura sarsi, responding more quickly to deposition of fresh algae than did the head-down polychaete Pectinaria hyperborea. Fatty acid biomarkers also indicated rapid ingestion of settling algae by the bivalves (especially Macoma) and the brittle star, while Pectinaria continued to ingest mainly bacteria. Fatty acid biomarkers did not indicate any unique dietary importance of ice algae released from melting ice. Longer-term inference from stable isotopes suggested that fresh microalgae contributed little to overall carbon assimilated by any of these species. Instead, deposit-feeders appeared to select a consistent fraction from the pool of sediment organic matter, probably heterotrophic microbes, microbial products, and reworked phytodetritus that form a longer-term sediment “food bank.” Redistribution of settled organic matter via scouring and accumulation by currents, as well as the multi-year life spans of macroinvertebrates, may further overwhelm effects of short-term variations in the timing, magnitude, and dispersion of blooms in the water column. More diet data are needed from midsummer to account for any lag in assimilation of fresh microalgae at these cold temperatures. Nevertheless, our results suggest that if annual sea ice cover is reduced, increased production of phytoplankton during longer ice-free periods could replace inputs of ice-associated microalgae to the sediment food bank used by deposit-feeders.

Field sampling of the macrobenthos from 23 stations in the Chukchi Sea was conducted during the 4th CHINARE (Chinese National Arctic Research Expeditions, July–August, 2010). We identified a total of 140 species of macrozoobenthos belonging to nine phyla, which were dominated by polychaetes (66), crustaceans (30), and mollusks (25), followed by echinoderms (9) and others (ten others, including four cnidarians, one oligochaete, one sipuncula, one priapulida, two bryozoans, and one urochordata). The dominant species were Aphelochaeta pacifica, Heteromastus filiformis, Nephtys ciliata, Nephtys caeca, Scoletoma fragilis, Golfingia margaritacea, Nuculana pernula, Macoma calcarea, Ennucula tenuis, Macoma inquinata, Musculus discors, Echinarachnius parma, and Ophiura sarsii, so there were more cold-eurythermal boreal immigrants than truly Arctic species (endemics). The average density and biomass (mean ± SD across all stations) of the total macrozoobenthos were (916 ± 907) ind/m2 and (902.9 ± 1 227.7) g/m2 (wet weight), respectively. Relatively high density and biomass were observed in the samples from the northeastern and southern Chukchi Sea. The spatial variation of benthic communities in the study sea area was relatively large; this spatial heterogeneity has led to high diversity and a patchy distribution pattern in the community structure. Compared to the 1st CHINARE (July–August, 1999), this investigation revealed different degrees of decreases in the average taxa numbers and the average density, abundance, and biodiversity in the area over the recent decade, which might be associated with global warming, human activities, and sea ice variations.

Using oxygen isotope ratios in terminal growth rings, we estimate the month of harvest of 32 Macoma nasuta shells from a single component Late Phase II (450–200 cal BP) assemblage from CA-CCO-297. Results suggest that clamming occurred throughout the year, but was most pronounced during two pulses in early summer and early winter. We relate the former to longer daylight in early summer that facilitated access to tidal flats and clamming, while the latter may relate more to a lack of other foraging opportunities. We compare the results to Macoma seasonality studies at two other Late Period sites (CA-SFR-171 and CA-SMA-6) and one Middle Period site (CA-ALA-17) on San Francisco Bay. The patterns at all four sites are similar in many regards, but differ in the details and highlight new information on ancient settlement patterns in the region.

In this study, we describe food availability and diet selection of the Red Knot Calidris canutus islandica wintering in three estuarine bays on the French Channel coast. We examined whether the distribution of birds is related to the density and availability of high quality prey. Results indicate strong seasonal and inter-annual variation in the abundance of birds and considerable variation in prey-item abundance and diet selection depending upon site. At Mont Saint-Michel Bay, the prey community was dominated by Baltic Tellins, Macoma balthica. As expected from their high meat-to-shell ratio, Macoma contributed more than 90% of the diet. Most of the cockles, Cerastoderma edule were too large and their quality too low to be preyed upon. Less than 100 km away, in Saint-Brieuc Bay, Red Knots mainly selected the Thin Tellin Tellina tenuis. Although Tellina are a lower quality prey than Macoma, they occurred at a high density and in some winters might explain why the number of Red Knots exceeds those at Mont ...

The present study aimed to investigate some hematological, histopathological and immunological parameters in the clam, Macoma edentula (Tellinidae) to serve as a reference for monitoring different environmental pollutants through the potential changes in the clam defence activities. Two localities at Lake Timsah, Ismailia exhibiting different levels of environmental contamination were selected for a comparative study of in vitro hemocyte activities. The results of DNA strand breakage in the Comet assay were expressed as the main tail DNA content and the mean tail length. The two measured parameters showed significant differences between the unpolluted and polluted samples. Water pollution was observed to cause significant histopathological changes in the mantle, gills and digestive gland of the tested clam, using light and electron microscopy. Histopathological changes of the mantle were represented in the arrangement of different cells vacuolation, swelling and distortion of gill filaments were also reported. The secretion of glandular cells increased in the polluted samples. Later on, such cells became completely necrotic and vacuolation was observed in most parts of the digestive gland cells. These results suggest that the use of such native bivalve in environmental biomonitoring can indicate the level of environmental pollutants including carcinogens in the examined animal model.

Texto completo. Acesso restrito. p. 108–114 Submitted by Santiago Fabio (fabio.ssantiago@hotmail.com) on 2013-10-14T19:01:05Z No. of bitstreams: 1 3333333333333.pdf: 539784 bytes, checksum: ce2658bac4bd4f948fea25e7b7e84b64 (MD5) Made available in DSpace on 2013-10-14T19:01:05Z (GMT). No. of bitstreams: 1 3333333333333.pdf: 539784 bytes, checksum: ce2658bac4bd4f948fea25e7b7e84b64 (MD5) Previous issue date: 2013 Liquid chromatography–inductively coupled plasma-mass spectrometry (LC–ICP-MS) was used for arsenic speciation analysis in tissues of bivalve mollusks (Anomalocardia brasiliana sp. and Macoma constricta sp.). Microwave and ultrasound radiation, combined with different extraction conditions (solvent, sample amount, time, and temperature), were evaluated for As-species extraction from the mollusks' tissues. Accuracy, extraction efficiency, and the stability of As species were evaluated by analyzing certified reference materials (DORM-2, dogfish muscle; BCR-627, tuna fish tissue; and SRM 1566b, oyster tissue) and analyte recovery tests. The best conditions were found to be microwave-assisted extraction using 200 mg of samples and water at 80 °C for 6 min. The agreement of As-species concentration in samples ranged from 97% to 102%. Arsenobetaine (AsB) was the main species present in bivalve mollusk tissues, while monomethylarsonic acid (MMA) and arsenate (As(V)) were below the limit of quantification (0.001 and 0.003 μg g− 1, respectively). Two unidentified As species also were detected and quantified. The sum of the As-species concentration was in agreement (90 to 104%), with the total As content determined by ICP-MS after sample digestion. Salvador

Although copper (Cu) is an essential element for life, leaching from boat paint can cause excess environmental loading in enclosed marinas. The effects of copper contamination on benthic macrofaunal communities were examined in three San Diego Bay marinas (America’s Cup, Harbor Island West and East) in Southern California, USA. The distribution of Cu concentration in sediments exhibited a clear spatial gradient, with hotspots created by the presence of boats, which in two marinas exceeded the effect range medium (ERM). Elevated sediment Cu was associated with differences in benthic assemblages, reduced species richness and enhanced dominance in America’s Cup and Harbor Island West, whereas Harbor Island East did not appear to be affected. At sites without boats there were greater abundances of some amphipods such as the species Desdimelita sp., Harpinia sp., Aoroides sp., Corophium sp., Podocerus sp., bivalves such as Lyonsia californica, Musculista senhousia, Macoma sp., and polychaetes such as Diplocirrus sp. In contrast, at sites with boats, densities of Pseudopolydora paucibranchiata, Polydora nuchalis, Euchone limnicola, Exogone lourei, Tubificoides spp. were enhanced. The limited impact on Harbor Island East suggests not only lower Cu input rates and increased water flushing and mixing, but also the presence of adequate defense mechanisms that regulate availability and mitigate toxic impacts. At all three marinas, Cu in tissues of several macrobenthic species exhibited Cu bioaccumulation above levels found in the surrounding environment. The annelids Lumbrineris sp. and Tubificoides spp., and the amphipod Desdimelita sp. contained high levels of Cu, suggesting they function as Cu bioaccumulators. The spionid polychaetes Polydora nuchalis and Pseudopolydora paucibranchiata had much lower Cu concentrations than surrounding sediments, suggesting they function as Cu bioregulators. The macrobenthic invertebrates in San Diego Bay marinas that tolerate Cu pollution (e.g. P. nuchalis, P. paucibranchiata, Euchone limnicola, Typosyllis sp., Tubificoides sp.) may function as indicators of high-Cu conditions, whereas the presence of Cu-sensitive species (e.g. Podocerus sp., Aoroides sp., Harpinia sp., Macoma sp., Lyonsia californica) may indicate healthier conditions (less Cu-stressed). Parallel responses by faunas of Shelter Island Yacht Basin, also in San Diego Bay, suggest potential for development of regional Cu contamination assessment criteria, and call for functional comparisons with other marinas and coastal water bodies.