The distribution of living benthic foraminifera on the continental slope and rise off southwest Norway

Surface sediment samples taken by ? corer from 45 stations on the Norwegian continental margin and in the Norway Basin have been investigated for their benthic foraminiferal content. Unlike previous studies, the living benthic foraminiferal fauna was differentiated from empty tests comprising the foraminiferal death assemblage. Factor analysis of both the living and dead faunal data reveals six living species assemblages and five corresponding dead assemblages. The additional living assemblage is characterized by the arenaceous speciesCribrostomoides subglobosum that dominates between 1400 and 2000 m water depth, but is rare in the dead faunal data.Trifarina angulosa and, to a lesser extent,Cibicides lobatulus characterize the shallowest foraminiferal assemblage from 200 to 600 m water depth, where it is associated with strong bottom currents and warm, saline Atlantic water of the North Atlantic Drift. On the slope between 600 and 1200 m water depth, theMelonis zaandami Species Assemblage dominates, particularly in areas characterized today by rapid sedimentation of terrigeneous material. Between 1000 and 1400 m depth, where the slope is covered by fine grained, organic-rich, terrigeneous mud, the living foraminiferal assemblage is characterized byCassidulina teretis andPullenia bulloides. Below 1400 m, three foraminiferal assemblages are found:C. subglobosum is found from 1400 to 2000 m,Cibicidoides wuellerstorfi andEpistominella exigua predominantly live from 2000 to 3000 m water depth, and below 3000 m,Oridorsalis umbonatus andTriloculina frigida dominate the fauna.All of theElphidium excavatum tests found in this study and theCassidulina reniforme tests found above 500 m water depth were found to be reworked.Analysis of the sediment grain-size distribution and the organic carbon content in surface samples from the deepest stations suggest that the abundance ofC. wuellerstorfi andE. exigua is positively correlated to relatively coarse (caused by planktic foraminifera) and organic-rich sediments, whereas high frequencies ofO. umbonatus andT. frigida coincide with low organic carbon content. We suggest thatC. wuellerstorfi is adapted to deep-sea environments with relatively high food supply, tolerating relatively low interstitial water oxygen content, whereasO. umbonatus may tolerate lower food supply prefering well-oxygenated interstitial waters.     

Recent benthic foraminiferal assemblages from cold-water coral mounds in the Porcupine Seabight

Cold-water coral ecosystems are characterised by a high diversity and population density. Living and dead foraminiferal assemblages from 20 surface sediment samples from Galway and Propeller Mounds were analysed to describe the distribution patterns of benthic foraminifera on coral mounds in relation to different sedimentary facies. Hard substrates were examined to assess the foraminiferal microhabitats and diversities in the coral framework. We recognised 131 different species, of which 27 prefer an attached lifestyle. Epibenthic species are the main constituents of the living and dead foraminiferal assemblages. The frequent species Discanomalina coronata was associated with coral rubble, Cibicides refulgens showed preference to the off-mound sand veneer, and Uvigerina mediterranea displayed abundance maxima in the main depositional area on the southern flank of Galway Mound, and in the muds around Propeller Mound. The distribution of these species is rather governed by their specific ecological demands and microhabitat availability than by the sedimentary facies. Benthic foraminiferal assemblages from coral mounds fit well into basin-wide-scale distribution patterns of species along the western European continental margin. The diversity of the foraminiferal faunas is not higher on the carbonate mounds as in their vicinity. The living assemblages show a broad mid-slope diversity maximum between 500 and 1,300 m water depth, which is the depth interval of coral mound formation at the Celtic and Amorican Margin. The foraminiferal diversity maximum is about 700 m shallower than comparable maxima of nematodes and bivalves. This suggests that different processes are driving the foraminiferal and metazoan diversity patterns.     

Living benthic foraminifera of the Okhotsk Sea: Faunal composition,standing stocks and microhabitats

Live (Rose Bengal stained) benthic foraminifera were investigated in surface sediment samples from the Okhotsk Sea to reveal the relationship between faunal characteristics and environmental parameters. Live benthic foraminifera were quantified in the size fraction > 125 µm in the upper 8 cm of replicate sediment cores, recovered with a multicorer at five stations along the Sakhalin margin, and at three stations on the southwestern Kamchatka slope. The stations are from water depths between 625 to 1752 m, located close or within the present Okhotsk Sea oxygen minimum zone, with oxygen levels between 0.3 and 1.5 ml l^- 1. At the high-productivity and ice-free Kamchatka stations, live benthic foraminifera are characterized by maximal standing stocks (about 1700-3700 individuals per 50 cm²), strong dominance of calcareous species (up to 87-91% of total live faunas), and maximal habitat depths (down to 5.2-6.7 cm depth). Vertical distributions of total faunal abundances exhibit a clear subsurface maximum in sediments. At the Sakhalin stations, which are seasonally ice-covered and less productive, live benthic foraminifera show lower standing stocks (about 200-1100 individuals per 50 cm²), lower abundance of calcareous species (10-64% of total live faunas), and shallower habitat depths (down to 2.5-5.4 cm depth). Faunal vertical distributions are characterized by maximum in the uppermost surface sediments. It is suggested that 1) lower and strongly seasonal organic matter flux, caused by the seasonal sea ice cover and seasonal upwelling, 2) lower bottom water oxygenation (0.3-1.1 ml l^- 1), and 3) more pronounced influence of carbonate undersaturated bottom water along the Sakhalin margin are the main factors responsible for the observed faunal differences. According to species downcore distributions and average living depths, common calcareous species were identified as preferentially shallow, intermediate and deep infaunal. Foraminiferal microhabitat occupation correlates with the organic matter flux and the depth of the oxygenated layer in sediments.     

Living benthic foraminifera of the Okhotsk Sea: Faunal composition, standing stocks and microhabitats

Live (Rose Bengal stained) benthic foraminifera were investigated in surface sediment samples from the Okhotsk Sea to reveal the relationship between faunal characteristics and environmental parameters. Live benthic foraminifera were quantified in the size fraction > 125 µm in the upper 8 cm of replicate sediment cores, recovered with a multicorer at five stations along the Sakhalin margin, and at three stations on the southwestern Kamchatka slope. The stations are from water depths between 625 to 1752 m, located close or within the present Okhotsk Sea oxygen minimum zone, with oxygen levels between 0.3 and 1.5 ml l^- 1. At the high-productivity and ice-free Kamchatka stations, live benthic foraminifera are characterized by maximal standing stocks (about 1700-3700 individuals per 50 cm²), strong dominance of calcareous species (up to 87-91% of total live faunas), and maximal habitat depths (down to 5.2-6.7 cm depth). Vertical distributions of total faunal abundances exhibit a clear subsurface maximum in sediments. At the Sakhalin stations, which are seasonally ice-covered and less productive, live benthic foraminifera show lower standing stocks (about 200-1100 individuals per 50 cm²), lower abundance of calcareous species (10-64% of total live faunas), and shallower habitat depths (down to 2.5-5.4 cm depth). Faunal vertical distributions are characterized by maximum in the uppermost surface sediments. It is suggested that 1) lower and strongly seasonal organic matter flux, caused by the seasonal sea ice cover and seasonal upwelling, 2) lower bottom water oxygenation (0.3-1.1 ml l^- 1), and 3) more pronounced influence of carbonate undersaturated bottom water along the Sakhalin margin are the main factors responsible for the observed faunal differences. According to species downcore distributions and average living depths, common calcareous species were identified as preferentially shallow, intermediate and deep infaunal. Foraminiferal microhabitat occupation correlates with the organic matter flux and the depth of the oxygenated layer in sediments.     

Live benthic foraminiferal faunas along a bathymetrical transect (140-4800 m) in the Bay of Biscay (NE Atlantic)

In a 10-stations bathymetrical transect in the Bay of Biscay, we observed important changes in the density, composition and microhabitats of live foraminiferal faunas from the outer continental shelf to the abyssal plain. Four zones are recognised: (1) at the upper continental shelf (140 m water depth), foraminiferal densities are very high and the superficial sediment is occupied by Bolivina subaenariensis and Valvulineria bradyana. Globobulimina spp., Chilostomella oolina and Nonion fabum dominate the infaunal niches, which are positioned close to the sediment-water interface due to a strong compaction of the vertical succession of redox zones. (2) At the upper continental slope stations (300-1000 m), foraminiferal densities are high and the superficial sediments are dominated by Uvigerina mediterranea/peregrina. Deeper in the sediment, intermediate infaunal niches are occupied by Melonis barleeanus. Due to a deeper oxygen penetration, the deep infaunal taxa Globobulimina spp. and C. oolina live at a considerable depth in the sediment. (3) At the mid and lower slope stations (1000-2000 m) in the superficial sediment Cibicidoides kullenbergi and Hoeglundina elegans progressively replace U. mediterranea. U. peregrina is still a dominant taxon, reflecting its preference for a somewhat intermediate organic flux level. Deep infaunal taxa become increasingly rare. (4) At the lower slope and abyssal plane stations (deeper than 2000 m), faunal densities are very low and the fauna is composed exclusively by shallow infaunal species, such as Nuttallides umboniferus and Melonis pompilioides. The foraminiferal data together with the pore water data in the sediment give evidence of the presence of a trophic gradient from very eutrophic settings at the upper continental shelf towards oligotrophic settings at the abyssal area.     

Benthic foraminifera off West Africa (1°N to 32°S): Do live assemblages from the topmost sediment reliably record environmental variability?

Recent benthic foraminifera (> 125 μm) were investigated from multicorer samples on a latitudinal transect of 20 stations between 1°N and 32°S along the upper slope off West Africa. Samples were selected from a narrow water depth interval, between 1200 and 1500 m, so that changes in water masses are minimized, but changes in surface productivity are important and the only significant environmental variable. Live (Rose Bengal stained) benthic foraminifera were counted from the surface sediment down to a maximum of 12 cm. Dead foraminifera were investigated in the top 5 cm of the sediment only. Five live and five dead benthic foraminiferal assemblages were identified using Q-mode principal component analysis, matching distinct primary productivity provinces, characterized by different systems of seasonal and permanent upwelling. Differences in seasonality, quantity, and quality of food supply are the main controlling parameters on species composition and distribution of the benthic foraminiferal faunas.To test the sensitivity of foraminiferal studies based on the uppermost centimeter of sediment only, a comparative Q-mode principal component analysis was conducted on live and dead foraminiferal data from the top 1 cm of sediment. It has been demonstrated that, on the upper slope off West Africa, most of the environmental signals as recorded by species composition and distribution of the “total” live and dead assemblages, i.e., including live and dead foraminifera from the surface sediment down to 12 cm and 5 cm, respectively, can be extracted from the assemblages in the top centimeter of sediment only. On the contrary, subsurface abundance maxima of live foraminifera and dissolution of empty tests strongly bias quantitative approaches based on the calculation of standing stocks and foraminiferal numbers in the topmost centimeter.     

Live (Rose Bengal stained) and dead benthic foraminifera from the oxygen minimum zone of the Pakistan continental margin (Arabian Sea)

Live (Rose Bengal stained) and dead benthic foraminiferal communities (hard-shelled species only) from the Pakistan continental margin oxygen minimum zone (OMZ) have been studied in order to determine the relation between faunal composition and the oxygenation of bottom waters. Samples were taken from 136 m to 1870 m water depth during the intermonsoon season of 2003 (March–April). Live foraminiferal densities show a clear maximum in the first half centimetre of the sediment only few specimens are found down to 4 cm depth. The faunas exhibit a clear zonation across the Pakistan margin OMZ. Down to 500 m water depth, Uvigerina ex gr. U. semiornata and Bolivina aff. B. dilatata dominate the assemblages. These taxa are largely restricted to the upper cm of the sediment. They are adapted to the very low bottom-water oxygen values (≈ 0.1 ml/l in the OMZ core) and the extremely high input of organic carbon on the upper continental slope. The lower part of the OMZ is characterised by cosmopolitan faunas, containing also some taxa that in other areas have been described in deep infaunal microhabitats. The contrast between faunas typical for the upper part of the OMZ, and cosmopolitan faunas in the lower part of the OMZ, may be explained by a difference in the stability of dysoxic conditions over geological time periods. The core of the OMZ has been characterised by prolonged periods of stable, strongly dysoxic conditions. The lower part of the OMZ, on the contrary, has been much more variable over time-scales of 1000s and 10,000 years because of changes in surface productivity and a fluctuating intensity of NADW circulation. We suggest that, as a consequence, well-adapted, shallow infaunal taxa occupy the upper part of the OMZ, whereas in the lower part of the OMZ, cosmopolitan deep infaunal taxa have repeatedly colonised these more intermittent low oxygen environments.     

Paleoceanography of the Mauritanian margin during the last two climatic cycles: From planktonic foraminifera to African climate dynamics

The last 220 ka of the MD03-2705 (18° 05.81′ N–21° 09.19′ W) sedimentary sequence, retrieved off the Cape Verde islands, was investigated using a multiproxy approach. Planktonic foraminifera assemblage analyses, coupled with isotopic measurements (δ¹⁸O) from benthic (Planulina wuellerstorfi) and planktonic (Globigerinoides ruber) foraminifera monospecific samples were conducted along the topmost 11 m of the sequence. High resolution X-ray fluorescence measurements (0.5 cm resolution), giving access to major element ratio, have completed the geochemical analyses along the core. Seasonal and annual past sea surface temperatures (SST) were quantitatively reconstructed. Local sea-surface salinity (SSS) changes were then estimated by coupling SST with planktonic δ¹⁸O data. Our data provide a set of both oceanic and continental markers of environmental changes along the north-western African margin. The major changes detected in our record are discussed in the light of the regional paleoceanographic and paleoclimatic history of the last 220 ka. Coupled oceanographic and atmospheric processes portray the climatic evolution of the area, and show strong links among the regional oceanography (water mass advection), the upwelling dynamics and the Intertropical Convergence Zone (ITCZ) migration. An increased upwelling activity (or influence of upwelling filaments) is noted at the end of the two last glacial periods, probably in response to a more southerly position of the ITCZ. Higher SSS are recorded over the area during arid intervals and were tentatively interpreted as signing a southward shift of the Cape Verde Frontal Zone. A detailed coupling between dust advection and SSS values over the site of study was noted during MIS6.5.     

Foraminiferes benthiques et bathymetrie: Le cenozoique du golfe de gascogne

Benthonic foraminifera are studied in the limited area of the Bay of Biscay and the present Aquitanian coasts.Recent populations have been dredged between 0 and 4450 m; their associations show a bathymetric zonation: faunas from an estuary (Gironde); in-shore and off-shore shelf; upper, middle and lower continental slope; abyssal fauna. The distribution of agglutinated Foraminifera and size/architectural variations of shells are also useful for bathymetrical zonation.Cenozoic Foraminifera are studied in two continental and four off-shore drillings in the Bay of Biscay and Aquitaine Basin. Results of recent faunal studies are used to select some species among the whole Tertiary population; main bathymetric associations are found that can illustrate the history of the Aquitanian area from Eocene to Recent. Two different areas can be described: a southern one with the Gouf' de Cap Breton and its anyon facies; a northern one with a continental margin which progrades to the west and is disturbed by the Pyrenean tectonic movements.It is only possible to make such a study in a restricted area, where water masses have almost constant bathymetric limits.     

Biogeography and Potential Exchanges Among the Atlantic Equatorial Belt Cold-Seep Faunas

Like hydrothermal vents along oceanic ridges, cold seeps are patchy and isolated ecosystems along continental margins, extending from bathyal to abyssal depths. The Atlantic Equatorial Belt (AEB), from the Gulf of Mexico to the Gulf of Guinea, was one focus of the Census of Marine Life ChEss (Chemosynthetic Ecosystems) program to study biogeography of seep and vent fauna. We present a review and analysis of collections from five seep regions along the AEB: the Gulf of Mexico where extensive faunal sampling has been conducted from 400 to 3300m, the Barbados accretionary prism, the Blake ridge diapir, and in the Eastern Atlantic from the Congo and Gabon margins and the recently explored Nigeria margin. Of the 72 taxa identified at the species level, a total of 9 species or species complexes are identified as amphi-Atlantic. Similarity analyses based on both Bray Curtis and Hellinger distances among 9 faunal collections, and principal component analysis based on presence/absence of megafauna species at these sites, suggest that within the AEB seep megafauna community structure is influenced primarily by depth rather than by geographic distance. Depth segregation is observed between 1000 and 2000m, with the middle slope sites either grouped with those deeper than 2000m or with the shallower sites. The highest level of community similarity was found between the seeps of the Florida escarpment and Congo margin. In the western Atlantic, the highest degree of similarity is observed between the shallowest sites of the Barbados prism and of the Louisiana slope. The high number of amphi-atlantic cold-seep species that do not cluster according to biogeographic regions, and the importance of depth in structuring AEB cold-seep communities are the major conclusions of this study. The hydrothermal vent sites along the Mid Atlantic Ridge (MAR) did not appear as “stepping stones” for dispersal of the AEB seep fauna, however, the south MAR and off axis regions should be further explored to more fully test this hypothesis.     

Planktonic foraminifera of the northern Indian Ocean: Distribution and preservation in surface sediments

In the northern Indian Ocean, planktonic foraminiferal tests accumulate in a wide variety of surface-water environments and depositional settings. This variability enables us to isolate the effects that surface-water ecology and differential dissolution have on the distribution of planktonic foraminifera from 251 geographically widespread surface sediment samples.Foraminiferal abundance varies from 0 to > 10⁴ whole foraminifera in the greater than 150 μm fraction per gram dry sediment. Values < 10 characterize the three deep basins of the equatorial Indian Ocean and the western Bay of Bengal. Foraminiferal tests are most abundant on carbonate covered Ninety-East and Carlsberg Ridges. Absolute abundance patterns are mainly controlled by non-ecological processes. Variations in dissolution resistant species (RSP) with water depth reveal that the foraminiferal lysocline (FL) varies regionally. The FL is deepest (3,800 m) in the equatorial region, rises abruptly to 3,300 m in the Arabian Sea, and varies from 2,600 m to near 2,000 m moving northward in the Bay of Bengal. Deep samples with anomalously low RSP (< 30%) suggest redeposition.Systematic geographic and depth-related variation is observed for the 17 most abundant foraminiferal species. Dissolution resistant species (G. menardii, G. tumida, G. dutertrei, P. obliquiloculata) generally exhibit a rapid and continuous increase in relative abundance at and below the FL. Susceptible species (G. ruber, G. bulloides, G. glutinata, for example) exhibit a rapid and continuous decrease in relative abundance at and below the FL. Moderately susceptible species (G. conglobatus, G. aequilateralis, G. conglomerata, for example) rapidly increase in abundance at the FL and systematically decrease with depth below the FL.Principal components analysis (PCA) of faunal data from minimally dissolved (< 30% RSP) samples reveals important ecologically related species intercorrelations. The major biogeographic gradient is the negative covarying relationship between aG. bulloides-G. glutinata species pair and a grouping ofG. sacculifer, G. conglobatus, G. aequilateralis, andG. ruber. PCA of all samples demonstrates how differential dissolution alters this and other species relationships. Species groupings that incorporateG. ruber, G. menardii, andG. dutertrei are particularly affected by dissolution.Comparison of average faunal data from minimally dissolved samples in the northern Indian Ocean with similar samples from other tropical regions suggests varying environmental factors produce distinct faunas within the tropical ocean. For example,G. bulloides, G. falconensis, andG. hexagona are significantly more abundant in northern Indian Ocean surface sediments while such species asG. ruber, G. sacculifer, G. dutertrei, andP. obliquiloculata dominate in other tropical regions.     

Corrélation des successions de l'Albien par les ammonites entre la Province Nord-Pacifique et les Provinces européenne et arctique du Domaine boréal : zonation, eustatisme et paléobiogéographie

The vertical distribution of Albian ammonites of the North Pacific Province is described on the basis of several sections located in Northern California. Nine Albian ammonite assemblages are identified, compared to the 4 previously described by Murphy in 1956. Owing to several gaps of observation possibly more assemblages could exist. In the North California Albian history, the first results show a succession of confinement periods - with numerous endemic faunas - followed by periods of open communications with other faunal provinces. As an example, the base of the Middle Albian is marked by exotic ammonites coming from the Tethyan realm (Oxytropidoceras, Lyelliceras) and from the Arctic Province of the Boreal realm (Gastroplites, Pseudopulchellia). These ammonites - except Oxytropidoceras - were not known in that area and are described relatively to their palaeobiogeographical interest. Although rare these migrant faunas give valuable elements to correlate these various provinces. Planktonic foraminifera confirm the existence of open sea communications during the uppermost Albian.With such faunal links, a comparison is proposed between the Albian ammonite zonation of Northern California and the standard and phyletic ones of Europe. This attempt suggests that the major connections between the three faunal provinces are established at second order peak transgressions in the Early and Middle Albian, and during the sea-level high of the Late Albian transgressive period. So, it seems that the vertical distribution of Albian non-endemic ammonites of North California and Europe is largely controlled by global eustatic events. Two palaeobiogeographic maps for Early and Middle Albian and one map for the late Late Albian show the migration outer of these exotic ammonites.     

Long-Term Observations of Epibenthic Fish Zonation in the Deep Northern Gulf of Mexico

A total of 172 bottom trawl/skimmer samples (183 to 3655-m depth) from three deep-sea studies, R/V Alaminos cruises (1964–1973), Northern Gulf of Mexico Continental Slope (NGoMCS) study (1983–1985) and Deep Gulf of Mexico Benthos (DGoMB) program (2000 to 2002), were compiled to examine temporal and large-scale changes in epibenthic fish species composition. Based on percent species shared among samples, faunal groups (≥10% species shared) consistently reoccurred over time on the shelf-break (ca. 200 m), upper-slope (ca. 300 to 500 m) and upper-to-mid slope (ca. 500 to 1500 m) depths. These similar depth groups also merged when the three studies were pooled together, suggesting that there has been no large-scale temporal change in depth zonation on the upper section of the continental margin. Permutational multivariate analysis of variance (PERMANOVA) also detected no significant species changes on the limited sites and areas that have been revisited across the studies (P>0.05). Based on the ordination of the species shared among samples, species replacement was a continuum along a depth or macrobenthos biomass gradient. Despite the well-known, close, negative relationship between water depth and macrofaunal biomass, the fish species changed more rapidly at depth shallower than 1,000 m, but the rate of change was surprisingly slow at the highest macrofaunal biomass (>100 mg C m⁻²), suggesting that the composition of epibenthic fishes was not altered in response to the extremely high macrofaunal biomass in the upper Mississippi and De Soto Submarine Canyons. An alternative is that the pattern of fish species turnover is related to the decline in macrofaunal biomass, the presumptive prey of the fish, along the depth gradient.     

Abyssal benthic foraminifera from the northwestern Pacific (Shatsky Rise) during the last 298 kyr

Benthic foraminifera in a gravity core from Shatsky Rise (northwestern Pacific, water depth 2612 m) show large fluctuations in accumulation rate, species composition and diversity over the last 298 kyr. The most important fluctuations (explaining more than 90% of the faunal variance) result from variations in relative abundance of the three most abundant species: Epistominella exigua, Alabaminella weddellensis and Uvigerina peregrina. High accumulation rates of U. peregrina, a species linked to high, continuous productivity, occurred with a 100 kyr periodicity at the end of glacial stages, and correspond to high mass accumulation rates of organic carbon. Peak accumulation rates of E. exigua occurred during glacial stage 4 and the middle part of glacial stages 8 and 6, whereas A. weddellensis was dominant in the early part of stages 8 and 6, and the late part of stage 3. A high abundance of these species probably indicates lower overall productivity than a high abundance of U. peregrina, and their relative and absolute abundances may be linked not simply to the amount of organic matter delivered to the sea floor, but to the intermittent delivery of fresh, easily degraded organic matter. The overall species diversity is negatively correlated to the relative abundance of E. exigua, but not to that of A. weddellensis, implying that these species have different environmental preferences, although both have been linked to periodic phytodetritus deposition in the present oceans.     

Distribution and some biological features of bottom skate <Emphasis Type="Italic">Bathyraja bergi</Emphasis> in the Russian waters of the Sea of Japan

The spatial and depth-related distribution, the size spectra, and the feeding peculiarities have been studied for the bottom skate Bathyraja bergi in the Russian waters of the Sea of Japan for the trawl catches performed in 1986?2015. The species is found at the depths of 38?577 m at the water temperature of 0.3?3.8°C; during the warm season, the fish keep mainly at the shelf, while they keep at the continental slope in the cold period of the year. This species is found nearly everywhere at the preferred depth range, except a part of the Strait of Tartary. The highest population density has been registered in the southwestern Peter the Great Gulf, along the border with the Korean waters. The schools of the bottom skate of the continental slope and the island shallows do not interact with each other. The specimens reach a body length of 129 cm and a body weight of 13.84 kg. The feeding habits indicate that this species is a predator; decapods (59.9%), cephalopods (23.0%), and fish (15.3%) dominate in the food. In spring, average daily ration constitutes 0.9% of the body weight. In the Russian waters of the Sea of Japan, the bottom skate is a common species, however, it is not abundant; the biomass of the population in this area is approximately 1500 tons.     

Deep-sea benthic foraminiferal recolonization of the 1991 Mt. Pinatubo ash layer in the South China Sea

A census count of Rose Bengal stained benthic foraminifera from the surface area on top of a 2 to 6 cm thick ashfall layer at three deep water stations along the western margin of the Philippines exhibits a unique assemblage composition of benthic foraminifera. The total number of benthic foraminifera is low and the ratio of living individuals to empty tests is high. Specific diversity is low, with a significant dominance of infaunal morphotypes including species of the genus Reophax (R. scorpiurus, R. bilocularis and R. dentaliniformis), which are regarded as successful recolonizers. Assemblages below the ash layers are diverse and contain many epifaunal suspension-feeding agglutinated and calcareous foraminifera. The 1991 Mt. Pinatubo eruption caused mass mortality of benthic foraminifera in a vast area of the eastern South China Sea followed by step-wise recolonization of the ash substrate. Three years after the eruption, the benthic foraminiferal community structure is still far from recovery to background levels.     

The importance of Late Miocene faunal exchanges between Eastern Mediterranean areas and Central Europe

Recent studies of mammal faunas from the Vienna and Pannonian Basins—in particular the assemblage from Kohfidisch in Burgenland (Austria)—provide new data on the faunal turnover at the Vallesian—Turolian transition. They demonstrated a considerable influence of the faunal exchanges between Greco-Iranian, Eastern European and Central European faunal provinces on renewal of mammal communities in Central Europe, particularly at MN10/MN11 boundary around 8.7 Ma. Five new comers from the Balkano-Iranian region (Gazella aff. pigrimi, ?Nisidorcas, Tragoportax gaudryi, Protoryx and Palaeoryx) coexisted in the Early Turolian of Central Europe with the Middle Miocene autochthonous (Orygotherium, Dorcatherium naui, Micromeryx, Euprox, Amphiprox anocerus and Miotragocerus pannoniae) and Late Miocene invaders from Eastern Europe (Procapreolus and Cervavitus). Dispersal events were close related to palaeoenvironmental and climatic changes.     

Ammonite habitats in the Early Tithonian of Western Tethys

Cccca, F. 1992 07 15: Ammonite habitats in the Early Tithonian of Western Tethys.
Habitats of Early Tithonian ammonites of Western Tethys are inferred from analysis of faunal spectra, functional morphology. facies characteristics and palaeogeography. Phylloceratina and Lytoceratina are included in a pelagic group characterized by taxa which could reach bathyal depths. This group is very abundant and dominant in some localities. A neritic nektobenthic group, relatively abundant in the Cmbria-Marche Apennines only. is composed of taxa characterired by species bearing simple sutures (some Simoceratidae and Pseudolissoceras ). probably living at shallower depth. The habitat of Haplploceras and some Oppeliidae. is interpreted to be close to the shelf margin/continental slope. Perisphinctids. Aspidoceratidae and some other Oppeliidae are provisionally included in an 'indeterminate' group including deep and shallow taxa. Quantitative studies of assemblage composition and comparison of faunal spectra successions from different pelagic regions allow the characterization of different pelagic environments. Bathymetric hypotheses by means of ammonites are discussed. Z Ammonoidea. habitats. facies, faunal spectra. Jurassic, Tithonian. Tethys .     

A global assessment of freshwater fish introductions in mediterranean-climate regions

Mediterranean-climate regions (med-regions) are global hotspots of endemism facing mounting environmental threats associated with human-related activities, including the ecological impacts associated with non-native species introductions. We review freshwater fish introductions across med-regions to evaluate the influences of non-native fishes on the biogeography of taxonomic and functional diversity. Our synthesis revealed that 136 freshwater fish species (26 families, 13 orders) have been introduced into med-regions globally. These introductions, and local extirpations, have increased taxonomic and functional faunal similarity among regions by an average of 7.5% (4.6–11.4%; Jaccard) and 7.2% (1.4–14.0%; Bray–Curtis), respectively. Faunal homogenisation was highest in Chile and the western Med Basin, whereas sw Cape and the Aegean Sea drainages showed slight differentiation (decrease in faunal similarity) over time. At present, fish faunas of different med-regions have widespread species in common (e.g. Gambusia holbrooki, Cyprinus carpio, Oncorhynchus mykiss, Carassius auratus, and Micropterus salmoides) which are typically large-bodied, non-migratory, have higher physiological tolerance, and display fast population growth rates. Our findings suggest that intentional and accidental introductions of freshwater fish have dissolved dispersal barriers and significantly changed the present-day biogeography of med-regions across the globe. Conservation challenges in med-regions include understanding the ecosystem consequences of non-native species introductions at macro-ecological scales.     

Biogeography of the octocorallian coelenterate fauna of southern Africa

The geographical and bathymetric distribution of southern African octocorals is analysed. Of the over 200 estimated species of regional octocorals, 81 confirmed and adequately described species are studied using a radial sector method. Two primary faunal components are recognized–endemic (53.3% of the fauna by numbers of species) and Indo-Pacific (39.4%). An Atlantic component contributes only minimally (about 1.7%), while the remaining fauna is made up of cosmopolites (2.8%) and scattered species (2.8%). A subantarctic component is not evident for the present-day, although evidence for previous contact is presented. A sister-group analysis using genera as a guide to sister species, shows the biogeographic affinities for the present-day fauna as a whole to be 45% Indo-Pacific, 31% cosmopolitan, 10% endemic, 10% Atlantic and 4% southern oceans (subantarctic). Applying the same method to only those genera with endemic species shows the affinities of the present-day endemic fauna to be 27.5% Indo-Pacific, 27.5% endemic, 24% cosmopolitan, 14% Atlantic and 7% subantarctic. Clearly defined boundaries for west, south, and east coast faunas (as recognized by previous authors in describing various intertidal faunas) are found not be present with regard to the octocoral fauna (largely due to its overwhelmingly subtidal nature). Instead two primary zoogeographic provinces are recognized–the Cape Endemic Province (extending from Liideritz to Inhaca Island) and the south-western fringe of the Indo-Pacific Province from East London north-eastwards. An overlap zone between these two is recognized between East London and Inhaca Island, with the region in the vicinity of Richards Bay having an essentially evenly mixed fauna (roughly 50% Cape Endemic Province and 50% Indo-Pacific). Of the 84 octocoral genera recorded for the region, seven (or 8.3%) are endemic, and of these, five are monotypic while two are ditypic. The fauna is shown to be predominantly sublittoral (about 95% by numbers of species), the shallow sublittoral (< 100 m in depth) being the region with highest species richness. Pennatulaceans are eurybathic (intertidal to 4756 m) and clearly show a high proportion of cosmopolites (20% of presently identified species). Soft corals are stenobathic and restricted to the intertidal, continental shelf and uppermost portion of the continental slope (<500m), while gorgonians are intermediate in depth distributon (intertidal to 1200 m). No cosmopolitan alcyonaceans are presently recorded. The centre of the Cape Endemic Province is the Agulhas Bank–an extensive region of shallow continential shelf (< 200 m in depth) between Cape Town and East London. Two regions of octocoral radiation for southern Africa are postulated–the Agulhas Bank and the western Indian Ocean.