Mollusks of the Utlyuk Liman (Sea of Azov): A Review of Species Composition with Remarks on Distribution and Ecology

Summarized data on the fauna composition, distribution, and ecology of gastropod and bivalve mollusks of the Utlyuk Liman in the northwestern part of the Sea of Azov is presented. The total number of mollusk species identified was 63; 43 species belonged to the class Gastropoda, and 20 species, to the class Bivalvia. The distribution of mollusks in the liman has extremely irregular character, whereas the distribution of species along the marine shore of Biryuchii Ostrov spit is more homogeneous. Euryhaline Mediterranean species represent the core of liman malacofauna; some taxa of the Ponto-Caspian zoogeographical complex (Dreissena polymorpha and species of the genus Theodoxus) and invader species from distant sea basins (Mya arenaria and Anadara inaequivalvis) were also identified.     

Changes in abundances of Alexandrium tamarense resting cysts after the tsunami caused by the Great East Japan Earthquake in Funka Bay,Hokkaido, Japan

The 2011 Great East Japan Earthquake and the subsequent huge tsunami greatly affected both human activity and the coastal marine ecosystem along the Pacific coast of Japan. The tsunami also reached Funka Bay in northern Japan and caused serious damage to the scallop cultures there, and this tsunami was believed to have affected the coastal environments in the bay. Therefore, we investigated the changes in the spatial abundance and distribution of the toxic dinoflagellates Alexandrium tamarense cysts before the tsunami (August 2010) and after the tsunami (May 2011, August 2011, May 2012 and August 2012) in the bay. Further, monthly sampling was conducted after the tsunami to identify seasonal changes of Alexandrium catenella/tamarense cysts and vegetative cells. Significant increases were observed in the populations of A. catenella/tamarense cysts, comparing the abundances before the tsunami (in August 2010; 70 ± 61 cysts g⁻¹ wet sediment) to those just after it (in May 2011; 108 ± 84 cysts g⁻¹ wet sediment), and both A. tamarense bloom (a maximum density was 1.3 × 10³ cells L⁻¹) and PSP (Paralytic Shellfish Poisoning) toxin contamination of scallops (9.4 mouse unit g⁻¹ was recorded) occurred in the bay. Seasonal sampling also revealed that the encystment of A. tamarense and the supply of the cysts to bottom sediments did not occur in the bay from September to April. These results strongly suggested that the mixing of the bottom sediments by the tsunami caused the accumulation of the toxic A. tamarense cysts in the surface of bottom sediment through the process of redeposition in Funka Bay. Moreover, this cyst deposition may have contributed to the toxic bloom formation as a seed population in the spring of 2011.     

Environmental Drivers of Benthic Flux Variation and Ecosystem Functioning in Salish Sea and Northeast Pacific Sediments

The upwelling of deep waters from the oxygen minimum zone in the Northeast Pacific from the continental slope to the shelf and into the Salish Sea during spring and summer offers a unique opportunity to study ecosystem functioning in the form of benthic fluxes along natural gradients. Using the ROV ROPOS we collected sediment cores from 10 sites in May and July 2011, and September 2013 to perform shipboard incubations and flux measurements. Specifically, we measured benthic fluxes of oxygen and nutrients to evaluate potential environmental drivers of benthic flux variation and ecosystem functioning along natural gradients of temperature and bottom water dissolved oxygen concentrations. The range of temperature and dissolved oxygen encountered across our study sites allowed us to apply a suite of multivariate analyses rarely used in flux studies to identify bottom water temperature as the primary environmental driver of benthic flux variation and organic matter remineralization. Redundancy analysis revealed that bottom water characteristics (temperature and dissolved oxygen), quality of organic matter (chl a:phaeo and C:N ratios) and sediment characteristics (mean grain size and porosity) explained 51.5% of benthic flux variation. Multivariate analyses identified significant spatial and temporal variation in benthic fluxes, demonstrating key differences between the Northeast Pacific and Salish Sea. Moreover, Northeast Pacific slope fluxes were generally lower than shelf fluxes. Spatial and temporal variation in benthic fluxes in the Salish Sea were driven primarily by differences in temperature and quality of organic matter on the seafloor following phytoplankton blooms. These results demonstrate the utility of multivariate approaches in differentiating among potential drivers of seafloor ecosystem functioning, and indicate that current and future predictive models of organic matter remineralization and ecosystem functioning of soft-muddy shelf and slope seafloor habitats should consider bottom water temperature variation. Bottom temperature has important implications for estimates of seasonal and spatial benthic flux variation, benthic–pelagic coupling, and impacts of predicted ocean warming at high latitudes.     

Benthic fauna affects recruitment from sediments of the harmful cyanobacterium Nodularia spumigena

Physical disturbance and feeding by macrofauna in the sediment can potentially affect bloom initiation of phytoplankton species that have benthic stages in their life cycle. In this experimental study, we investigated how different species of macrozoobenthos can affect the recruitment of Nodularia spumigena from the sediment to the water column. N. spumigena is a toxic, nitrogen-fixing filamentous cyanobacterium, which forms large summer blooms in the Baltic Sea. Benthic recruitment from resting stages (akinetes) and vegetative cells deposited on the seafloor have long been suspected to initiate the blooms. We found that, depending on species-specific traits, deposit-feeding macrofauna (an amphipod, Monoporeia affinis, a bivalve, Macoma balthica and an invasive polychaete, Marenzelleria cf. arctia) has the potential to either reduce or facilitate recruitment of this cyanobacterium. Shorter filament length in treatments with fauna than in the treatment without indicates feeding on or mechanical destruction of N. spumigena by the animals. Our results show the importance of an often overlooked aspect of phytoplankton bloom initiation, the role of macrozoobenthos.     

Benthic indices and ecological quality of shallow Algeria fine sand community

This study applies six macrozoobenthos-based biotic indices in the shallow coastal waters along the Algerian coast (southern Mediterranean Sea) to establish a reference situation for future use. These shallow fine sand communities were sampled in seven bays along the Algerian coast during the 1980s and the beginning of the 1990s. For the first time, some of the benthic indices used nowadays in Europe for the implementation of the WFD and/or in North America for the Clean Water Act were used to analyze the data collected twenty years ago in order to assess the biological quality status of the Algerian shallow fine sand communities and to provide ecological classifications for the fine sand community along the Algerian coast. The faunal composition showed that the fine sand communities belonged to a Well-Calibrated Fine Sand (WCFS) biocenosis characterized by high species richness and high H′ Shannon-Weaver diversity, with moderate abundance levels only. In the bays of Fetzara, Jijel, Bejaia, Bou Ismail and Arzew (though not in bays of Algiers and Oran), H′ is >4.5, which implies highly diversified communities. The results of the six benthic indices (H′, AMBI, M-AMBI, BENTIX, BOPA and ITI) suggest that good and high quality status assessments are prevalent in all seven bays for the benthic shallow sand communities along the Algerian coast. Nevertheless, the effect of pollution was observed at a small number of sites in the Arzew, Oran and Algiers bays. For example, in Algiers Bay, an east-west quality gradient revealed the effect of organic matter input.     

Mycobiota of the giant oyster <Emphasis Type="Italic">Crassostrea gigas</Emphasis> (Thunberg, 1787) (Bivalvia) from the Peter the Great Bay of the Sea of Japan

Mycological investigation of the Pacific (giant) oyster Crassostrea gigas (Thunberg, 1793) (Bivalvia) from the Peter the Great Bay of the Sea of Japan was carried out. The taxonomic composition of filamentous fungi associated with C. gigas was studied. The taxonomic composition of the fungi associated with the giant oyster included 22 species of filamentous fungi of which 17 species were identified. The latter belonged to six genera: Alternaria, Aspergillus, Botrytis, Fusarium, Penicillium, and Trichoderma. The distribution of filamentous fungi in the internal organs of the bivalve mollusk was studied.     

Sedimentology,taphonomy, and palaeoecology of a laminated plattenkalk from the Kimmeridgian of the northern Franconian Alb (southern Germany)

At Wattendorf in the northern Franconian Alb, southern Germany, centimetre- to decimetre-thick packages of finely laminated limestones (plattenkalk) occur intercalated between well bedded graded grainstones and rudstones that blanket a relief produced by now dolomitized microbialite-sponge reefs. These beds reach their greatest thickness in depressions between topographic highs and thin towards, and finally disappear on, the crests. The early Late Kimmeridgian graded packstone–bindstone alternations represent the earliest plattenkalk occurrence in southern Germany. The undisturbed lamination of the sediment strongly points to oxygen-free conditions on the seafloor and within the sediment, inimical to higher forms of life. The plattenkalk contains a diverse biota of benthic and nektonic organisms. Excavation of a 13 cm thick plattenkalk unit across an area of 80 m² produced 3500 fossils, which, with the exception of the bivalve Aulacomyella, exhibit a random stratigraphic distribution. Two-thirds of the individuals had a benthic mode of life attached to hard substrate. This seems to contradict the evidence of oxygen-free conditions on the sea floor, such as undisturbed lamination, presence of articulated skeletons, and preservation of soft parts. However, palaeoecological and taphonomic analyses indicate that the benthic faunal elements are allochthonous having settled out of suspension and thus must have been derived from hard substrate areas of neighbouring topographic highs. Solely the bivalve Aulacomyella, which occurs concentrated on a single bedding plane, may have colonised the plattenkalk depression during brief periods of oxygenation. Alternatively, a pseudoplanktonic mode of life, attached to floating sea weed, is envisaged for the bivalve. The formation of the plattenkalk is related to local and global factors: a drop in relative sea level caused the death of the microbialite-sponge reefs. Restricted circulation in depressions between the crests of the former reefs led to anoxic conditions and the formation of finely laminated sediments stabilised by microbial mats. The small depressions received sediment and skeletal elements of benthic organisms that were swept off neighbouring topographic highs by storms and that entered the depressions partly as turbidity currents, partly as suspension clouds. A rise in the relative sea level finally terminated the restricted circulation in the depressions and closed the taphonomic window that led to the preservation of the plattenkalk biota.     

Temperature thresholds of opportunistic annelids used as benthic indicators of aquaculture impact in Newfoundland (Canada)

In Newfoundland, Canada, aquaculture sites set up over deep, hard bottom substrates dictate the use of visual indicators to monitor aquaculture footprints on the seafloor. Opportunistic annelids (referred to as opportunistic polychaete complexes, or OPC) are among these indicators. The effect of temperature on the distribution and survival of Ophryotrocha cyclops, the species constituting OPC in Newfoundland aquaculture sites is not known. To address this knowledge gap, this study assesses O. cyclops survival at different temperatures in the laboratory, and describes relationships between O. cyclops presence and seafloor temperatures measured in the field. Results show that worms died within two days at temperatures > 12 °C in the laboratory, and appear restricted to temperatures below 7.9 °C at aquaculture sites, tending to be more frequent at temperatures below 5 °C. We recommend that seafloor temperature be recorded and considered in the assessment of benthic aquaculture impact based on OPC presence.     

Degradation and recovery of an Arctic benthic community under organic enrichment

Fast development of mariculture in the world leads to increasing of the load on natural habitats, especially due to organic enrichment. There are a few investigations concerning the effect of additional organic loading on the Arctic benthic communities. The main goal of our research was to ascertain the impact of mussel farm on the benthic community in the White Sea and its following recovery after mussel farm removal. We performed annual observations from 1988 to 2011. During the mussel farm functioning, two stages of organic enrichment impact on community structure were recorded: in the first 2 years, diversity and proportion of deposit feeders increased but later all studied characteristics of the benthic community decreased significantly. After the mussel farm removal, the benthic community started to restore and we distinguished several stages of recovery succession. Native structure of benthic community began to recover 8 years after organic loading had ceased, when selective deposit feeding bivalves Portlandia arctica Gray appeared in the benthos. 4–6 years later it became the only dominating species in the studied benthic community. Therefore, in the White Sea, native structure recovery of the Arctic benthic community after the severe disturbance took about 15 years.     

Taxonomy and Diversity of Freshwater Bivalve Mollusks (Bivalvia) of China (Based on Analysis of the Catalog by He and Zhuang, 2013)

The diversity of freshwater Bivalvia in China was assessed on the basis of critical analysis of original and published data on the fauna, morphology, taxonomy, and molecular genetics of this group. The taxonomic composition of the following genera has been considered in depth: Anemina Haas 1969, Cristaria Schumacher 1817, Sinanodonta Modell 1944, Lanceolaria Conrad 1853, Middendorffinaia Moskvicheva et Starobogatov 1973, Nodularia Conrad 1853, Unio Philipsson in Retzius 1788, Inversidens Haas 1911, Sphaerium Scopoli 1777, Pisidium Pfeiffer 1821, Odhneripisidium Kuiper 1962, and Euglesa Leach in Jenyns 1832 = Cyclocalyx Dall 1905. No fewer than 170 bivalve species were demonstrated to occur in the freshwater areas of China. Underestimation of the Bivalvia species abundance in previous studies, including the latest catalog of the Chinese Bivalvia (He and Zhuang, 2013), may be accounted for mostly by inadequate use of morphological methods and limited faunistic data, as well as a little number of taxonomic works supported by molecular data. Both the generic and specific compositions of the Chinese Unioniformes and Luciniformes have been significantly extended and updated. Based on a complex study of conchological characters, the following synonymy was established for three species: Sinanodonta qingyuani He et Zhuang 2013 = S. woodiana (Lea 1834) syn. n., Lanceolaria yueyingae He et Zhuang 2013 = L. eucylindrica C. Lin 1962 syn. n., Acuticosta jianghanensis He et Zhuang 2013 = Nodularia douglasiae (Griffith et Pidgeon 1833) syn. n.     

Assessment of turtle grass (Thalassia testudinum ex Banks Konig) community structure in a UNESCO Biosphere Reserve

Tropical turtle grass beds (Thalassia testudinum) were investigated in an UNESCO Biosphere Reserve in St. Johns Island, United States Virgin Islands. Four coastal bays were studied to assess floral characteristics, benthic invertebrate density and secondary production. These bays varied with respect to oceanic exposure and anthropogenic stresses. Results indicate that Coral Bay Harbor, the most anthropogenetically impacted site, had the highest T. testudinum biomass, but the lowest floral diversity. Its faunal community was dominated by small polychaetes with significantly lower secondary production. The most protected site (Hurricane Hole) maintained the highest floral and faunal species richness, faunal density, faunal diversity, and secondary production. The other two bays, Great Lameshur and Little Lameshur, demonstrated intermediate plant biomass and species richness, faunal density and secondary production. Each of these bays, however, had high oceanic exposure due to their orientation which also demonstrated a sediment size shift to larger particles compared to the other sites. One unique finding was a significant increase in the shoot:root ratio in Little Lameshur where green turtle (Chelonia mydas) grazing was frequently observed, suggesting a potential top-down structuring force in this bay.     

山东半岛南部海湾底栖动物群落生态特征及其与水环境的关系

2006-2007年对山东半岛南部4个海湾(荣成湾、桑沟湾、靖海湾和五垒岛湾)19个站位的底栖动物群落结构特征进行了研究,并对14个环境因素和底栖动物群落生态特征分别进行主成分分析和Spearman相关分析。结果显示,荣成湾、桑沟湾和靖海湾的底栖动物种类中,多毛类所占比例最高,而五垒岛湾仅秋、冬季多毛类所占比例最高。根据聚类分析和非度量多维标度方法分析,4季底栖动物群落均可分为2个群落,春、冬季的第一聚群为靖海湾和五垒岛湾,第二聚群为荣成湾和桑沟湾。秋季荣成湾、桑沟湾、靖海湾组成第一聚群,第二聚群由五垒岛湾构成。夏季,底栖动物Shannon-Wiener多样性指数(H')与采样深度和总碱度呈显著正相关,与水温呈极显著的负相关关系。秋季,与硝酸盐呈负相关关系,说明富营养化对山东半岛南部4个海湾大型底栖动物群落产生了一定负面影响。ABC曲线法分析显示,荣成湾和桑沟湾底栖动物的丰度优势度曲线与生物量优势度曲线相交,表明荣成湾和桑沟湾大型底栖动物群落处于中度干扰状态,密集的养殖活动可能对其生态系统带来了巨大影响,加强海水养殖管理,强化生态健康养殖理念,合理利用海洋生物资源,对大型底栖动物群落的稳定性具有重要意义。     

What can 18S rDNA do for bivalve phylogeny?

Molecular characteristics, especially 18S rDNA sequences, may be of great value for the study of bivalve evolution and its numerous morphological convergencies once the reliability of these data can be evaluated. The analysis of 11 published complete molluscan sequences and two new ones,Arca noae andAtrina pectinata, reveals considerable differences in relative substitution rates. The gastropod and eulamellibranch species have the fastest and Atrina species have the slowest rates. Two methods are used to assess the information contents of the dataset in addition to bootstrap analysis, spectral analysis, and the “pattern of resolved nodes” technique. Tree reconstructions by parsimony, neighbor-joining, and maximum-likelihood differ in regard to the position of the eulamellibranch family Mactridae and ofCrassostrea. Although there is a signal for the monophyly of Bivalvia, Mactridae cluster with Gastropoda in most runs, rendering Bivalvia diphyletic. The position ofCrassostrea was extremely variable, probably due to the high substitution rate of this species.Atrina roots deeper thanArca in all trees, although a corresponding signal in spectral analysis is absent. Phylogenetic signals among the three pectinid species are low but sufficient to resolve the branching pattern. The tree inferred from the 18S rDNA and from morphological data has Bivalvia monophyletic with a basal polytomy of Mactridae,Crassostrea, and the remaining Pteriomorphia, whereArca branches off before Atrina and the Pectinidae.Argopecten is sister group to the other two pectinids; 18S sequence data will have great impact on our understanding of bivalve phylogeny, but only when more sequences of similar substitution rates are available. Correspondence to: G. Steiner     

Trophodynamics and functional feeding groups of North Sea fauna: a combined stable isotope and fatty acid approach

The trophodynamics of pelagic and benthic animals of the North Sea, North Atlantic shelf, were assessed using stable isotope analysis (SIA) of natural abundance carbon and nitrogen isotopes, lipid fingerprinting and compound-specific SIA (CSIA) of phospholipid-derived fatty acids (PLFAs). Zooplankton (z), epi- and supra-benthic macrofauna were collected in the Southern Bight, at the Oyster Grounds and at North Dogger, 111 km north of the Dogger Bank. The study included 22 taxonomic groups with particular reference to Mollusca (Bivalvia and Gastropoda) and Crustacea. Primary consumers (Bivalvia) were overall most ¹⁵N enriched in the southern North Sea (6.1‰) and more depleted in the Oyster Grounds (5.5‰) and at North Dogger (2.8‰) demonstrating differences in isotopic baselines for bivalve fauna between the study sites. Higher trophic levels also followed this trend. Over an annual cycle, consumers tended to exhibit ¹⁵N depletion during spring followed by ¹⁵N enriched signatures in autumn and winter. The observed seasonal changes of δ ¹⁵N were more pronounced for suspension feeders and deposit feeders (dfs) than for filter feeders (ffs). The position of animals in plots of δ ¹³C and δ ¹⁵N largely concurred with the expected position according to literature-based functional feeding groups. PLFA fingerprints of groups such as z were distinct from benthic groups, e.g. benthic ffs and dfs, and predatory macrobenthos. δ ¹³C_PLFA signatures indicated similarities in ¹³C moiety sources that constituted δ ¹³C_PLFA. Although functional groups of pelagic zooplankton and (supra-) benthic animals represented phylogenetically distinct consumer groups, δ ¹³C_PLFA demonstrated that both groups were supported by pelagic primary production and relied on the same macronutrients such as PLFAs. Errors related to the static categorization of small invertebrates into fixed trophic positions defined by phylogenetic groupings rather than by functional feeding groups, and information on seasonal trophodynamic variability, may have implications for the reliability of numerical marine ecosystem models.     

Indirect effects of Atrina zelandica on water column nitrogen and oxygen fluxes: The role of benthic macrofauna and microphytes

The effects of ecosystem engineers can be mediated by direct and indirect interactions. For suspension-feeding bivalves that contribute to benthic-pelagic coupling, indirect effects have been linked to hydrodynamics; however, the influence of these ecosystem engineers may also operate through interactions with surrounding sediments, microphytes and macrofauna that, in turn, affect nutrient and oxygen fluxes. This study investigated the indirect effects of an epibenthic suspension-feeding bivalve (Atrina zelandica) on ammonium and nitrate-nitrite effluxes from the sediment, and oxygen consumption in the overlying waters, under dark conditions, at two sites with different environmental characteristics. Location-dependent effects were observed in the relative strength of the effect of Atrina on microphyte and macrofaunal abundance. The difference between the strength of the effect of Atrina on macrofauna between sites was not driven by a single species or type of species; rather all the species decreasing in abundance away from Atrina were small species that utilised the sediment water interface. Location-dependent effects were also observed in the relative strength of the effect of microphyte and macrofaunal abundance on oxygen and nutrient fluxes. While microphytes were an important consumer of oxygen at one site, at the other site, small infaunal macrofauna were important. Similarly, the strength of the effect of surrounding macrofauna on ammonium efflux varied between sites. These findings demonstrate the importance of natural history and species functions for understanding complex responses. They suggest that indirect effects by key benthic macrofaunal species in marine systems can also be important to benthic-pelagic coupling. In particular, while key species are often large, excretion and respiration of smaller macrofauna can be important to the exchange of nutrients near the seafloor and oxygen consumption in the benthic boundary layer.     

Species composition,richness, and distribution of marine bivalve molluscs in Bahía de Mazatlán,México

We describe the composition and distribution of bivalve molluscs from the sandy and rocky intertidal and the shallow subtidal environments of Bahía de Mazatlán, México. The bivalve fauna of the bay is represented by 89 living species in 28 families, including 37 new records and four range extensions: Lithophaga hastasia, Adula soleniformis, Mactrellona subalata, and Strigilla ervilia. The number of species increases from the upper (44) and lower intertidal (53) to the shallow subtidal (76), but only 11 (17%) have a wide distribution in the bay (i.e., found in all sampling sites and environments). The bivalve assemblages are composed of four main life forms: 27 epifaunal species, 26 infaunal, 16 semi-infaunal, and 20 endolithic. A taxonomic distinctness analysis identified the sampling sites and environments that contribute the most to the taxonomic diversity (species to suborder categories) of the bay. The present work increased significantly (31%) to 132 species previous inventories of bivalves of Bahía de Mazatlán. These species represent 34% of the bivalve diversity of the southern Golfo de California and approximately 15% of the Eastern Tropical Pacific region.     

Cenozoic fossil nautiloids (Cephalopoda) from Kutch,western India

The Cenozoic marine succession of Kutch, India, is rich in benthic molluscs and other invertebrates, but nautiloids are very scanty. Three nautiloid species, with two being new, are reported here: Deltoidonautilus vredenburgi n. sp. from the Early Eocene Naredi Formation, Cimomia forbesi (d’Archiac and Haime, 1854) from the Middle Eocene Harudi Formation, and Aturia gujaratensis n. sp. from the Early Miocene Khari Nadi and Chhasra formations. Taphonomic and sedimentary features reveal that the Eocene nautiloids were parautochthonous whereas the Miocene species might have been transported post-mortally for some distance. Palaeobiogeographic distribution of the Cenozoic nautiloids of the Indian subcontinent and other parts of the world reveals that though the genera are pandemic the species are often endemic to a basin or a province. Specific endemism and pattern of broad faunal similarity of nautiloids among different provinces within the Tethys Realm (sensu Harzhauser et al., 2002) mimic those of the benthic molluscs during the Palaeogene.     

Benthic foraminiferal assemblages between two major extinction events: the Paleocene El Kef section,Tunisia

The development of benthic foraminiferal assemblages from the Paleocene outcrops of the El Haria Formation near El Kef, Tunisia is discussed qualitatively and quantitatively. The aim of the study is to reconstruct the paleoenvironmental evolution between the K/Pg boundary interval and the late Paleocene event, and to compare this evolution with results from other sites along the southern Tethyan margin. Eighty-four samples, covering virtually the entire Paleocene, provide a dataset that allows detailed qualitative and multivariate analysis. The benthic foraminiferal faunas indicate a complex pattern of environmental changes during the Paleocene, marked by the succession of different benthic associations. Following the K/Pg boundary event, community restoration was characterized by the gradual build-up of faunal diversity. Decreasing dominance and the entry of taxa common to normal marine, outer neritic to upper bathyal environments indicate the completion of the ecosystem restoration in Zone Plb. A highly diverse benthic foraminiferal assemblage persisted throughout the remainder of the early Paleocene into the earliest late Paleocene. At the P3a-P3b zonal transition relative sea-level lowering is evidenced by the sudden disappearance or decreasing abundance of deeper-water taxa (e.g. Anomalinoides affinis, A. susanaensis, Gavelinella beccariiformis). Neritic deposition continued into Zone P4, when trophic levels at the seafloor increased as indicated by the entry and increasing dominance of species such as Anomalinoides cf. aegyptiacus, Bulimina midwayensis, and B. strobila, which we consider to be sensitive to eutrophication. The combined effect of shallowing and the subsequent eutrophication led to the establishment of assemblages similar to late Paleocene benthic foraminiferal assemblages from Egyptian sections, some of which record the latest Paleocene extinction event. These assemblages were interpreted to be indicative of a middle neritic, highly eutrophic environment. Enhanced vertical fluxes of organic matter along the southern Tethyan margin may have resulted from intensified upwelling. This eventually led to oxygen deficiency at the seafloor. It appears that oxygen-deficient, high-productivity shelves were a common feature of the southern Tethyan margin during the latest Paleocene.     

Benthic foraminiferal paleoenvironmental reconstruction from the Upper Coniacian-Lower Campanian succession in north-western Tunisia

Quantitative analysis of benthic foraminifera is used to characterize the paleoenvironments of the Upper Coniacian-Lower Campanian succession in the Jbil section of north-western Tunisia. Foraminiferal parameters and benthic foraminiferal assemblages show that the studied section includes four distinct paleoenvironmental phases. From oldest to youngest, these are as follows: (1) an interval with a Praebulimina reussi assemblage with infaunal ratios as high as 96.1%. High abundances of P. reussi, reflecting an increase in organic matter flux to the seafloor (meso-to eutrophic) under oxygenated bottom-water conditions. (2) An interval characterized by a Gavelinella costulata assemblage with mixed infaunal/epifaunal foraminifera with higher Fisher's alpha values (ranging from 4 to 15.2), reflecting mesotrophic conditions in an outer shelf environment. (3) An interval with a Gaudryina laevigata assemblage indicative of a middle to outer shelf environment; there is a considerable increase in infaunal agglutinated foraminifera, as well as a relatively abundant and moderately diversified oxic/suboxic foraminifera. (4) The final interval occurs in the lower Campanian (the Globotruncana ventricosa Zone) and includes a Bolivinoides decoratus assemblage reflecting an outer shelf to upper bathyal environment. It contains a higher planktonic percentage and biodiversity with a slight increase in dysoxic species; the mixed infaunal/epifaunal content (57.6 to 73.3%) reflects mesotrophic conditions. Four well-recognized major sea-level falls are matched by the dual signatures of eustatic sea-level changes. These are coincident with the results of this study, which represent the first documentation of these events in Tunisian faunal and paleoenvironmental changes, at the following boundaries: Coniacian/Santonian, intra-Santonian, Santonian/Campanian, and intra-early Campanian.     

Taxonomic composition and seasonal dynamics of the meroplankton of the coastal zone of the northeastern Black Sea

The composition and dynamics of the numerical density of meroplankton in the Bays and Seaports of the Northeastern Black Sea, viz., Novorossiysk, Tuapse, Gelendzhik, and Anapa were studied in the long-term aspect. The larvae of the benthic invertebrates of 73 taxa were identified. Meroplankton had their peak abundance period from May to September. Larvae of mollusca Mytilus galloprovincialis and Cardiidae gen sp. (Bivalvia) were dominant in the spring; larvae of mollusca Bittium reticulatum (Gastropoda), Mytilaster lineatus were dominant in the summer, and M. galloprovincialis, Anadara cf. inaequivalvis, Chamelea gallina (Bivalvia) were dominant in the autumn. Polychaete and cirriped larvae occurred in the plankton during the spring-autumn season. Complex species that are tolerant to pollution, such as Amphibalanus improvisus, M. lineatus, B. reticulatum, and the genus Polydora were abundant in Novorossiysk and the Tuapse.