Movement, connectivity and population structure of the intertidal fish <i>Lipophrys pholis</i> as revealed by otolith oxygen and carbon stable

The shanny Lipophrys pholis is an intertidal fish commonly found in Portuguese coastalwaters. Spawning takes place from early autumn to mid spring, after which demersal eggshatch and larvae disperse along the coast. Two to three months later, young juvenilesreturn to the tide pools to settle. However, information on fish movement, habitatconnectivity and population structure is scarce for this species. One hundred and twentyearly juveniles (16–35 mm) were collected in April 2014 from six rocky beaches along thewestern and south Portuguese coasts (Agudela, Cabo do Mundo, Boa Nova, Peniche, Sinesand Olhos de Água). δ18O and δ13C were determined by isotope-ratio mass spectrometry.Data were analysed to determine whether isotopic signatures could be used to assess thedegree of separation between individuals collected from different locations. Mean δ13Cand δ18O values ranged from −0.02‰ to 1.14‰ and −7.77‰ to −6.62‰, respectively.Both seawater temperature and salinity caused differences in otolith δ18O among the fourmain sampling areas. The variation among areas in δ13C was most likely related toslight differences in the diet, growth and metabolism of fish. The distinct isotopicsignatures, at least for the northern and central areas, suggested low levels of connectivityacross large spatial scales during the juvenile stage. Furthermore, similar isotopicsignatures within the same area indicated some degree of larval oceanic retention at shortspatial scales. This study suggests that stable isotope records in otoliths could provideinformation about the home residency, movements and habitat connectivity of intertidalfishes

Ecology and Biogeography of Free-Living Nematodes Associated with Chemosynthetic Environments in the Deep Sea: A Review

Background: Here, insight is provided into the present knowledge on free-living nematodes associated with chemosynthetic environments in the deep sea. It was investigated if the same trends of high standing stock, low diversity, and the dominance of a specialized fauna, as observed for macro-invertebrates, are also present in the nematodes in both vents and seeps. Methodology: This review is based on existing literature, in combination with integrated analysis of datasets, obtained through the Census of Marine Life program on Biogeography of Deep-Water Chemosynthetic Ecosystems (ChEss). Findings: Nematodes are often thriving in the sulphidic sediments of deep cold seeps, with standing stock values ocassionaly exceeding largely the numbers at background sites. Vents seem not characterized by elevated densities. Both chemosynthetic driven ecosystems are showing low nematode diversity, and high dominance of single species. Genera richness seems inversely correlated to vent and seep fluid emissions, associated with distinct habitat types. Deep-sea cold seeps and hydrothermal vents are, however, highly dissimilar in terms of community composition and dominant taxa. There is no unique affinity of particular nematode taxa with seeps or vents. Conclusions: It seems that shallow water relatives, rather than typical deep-sea taxa, have successfully colonized the reduced sediments of seeps at large water depth. For vents, the taxonomic similarity with adjacent regular sediments is much higher, supporting rather the importance of local adaptation, than that of long distance distribution. Likely the ephemeral nature of vents, its long distance offshore and the absence of pelagic transport mechanisms, have prevented so far the establishment of a successful and typical vent nematode fauna. Some future perspectives in meiofauna research are provided in order to get a more integrated picture of vent and seep biological processes, including all components of the marine ecosystem

Open Ocean Deep Sea

The deep sea comprises the seafloor, water column and biota therein below aspecified depth contour. There are differences in views among experts and agencies regarding the appropriate depth to delineate the “deep sea”. This chapter uses a 200 metre depth contour as a starting point, so that the “deep sea” represents 63 per cent of the Earth’s surface area and about 98.5 per cent of Earth’s habitat volume (96.5 per cent of which is pelagic). However, much of the information presented in this chapter focuses on biodiversity of waters substantially deeper than 200 m. Many of the other regional divisions of Chapter 36 include treatments of shelf and slope biodiversity in continental-shelf and slope areas deeper than 200m. Moreover Chapters 42 and 45 on coldwater corals and vents and seeps, respectively, and 51 on canyons, seamounts and other specialized morphological habitat types address aspects of areas in greater detail. The estimates of global biodiversity of the deep sea in this chapter do include all biodiversity in waters and the seafloor below 200 m. However, in the other sections of this chapter redundancy with the other regional chapters is avoided, so that biodiversity of shelf, slope, reef, vents, and specialized habitats is assessed in the respective regional or thematic chapters. AB - The deep sea comprises the seafloor, water column and biota therein below aspecified depth contour. There are differences in views among experts and agencies regarding the appropriate depth to delineate the “deep sea”. This chapter uses a 200 metre depth contour as a starting point, so that the “deep sea” represents 63 per cent of the Earth’s surface area and about 98.5 per cent of Earth’s habitat volume (96.5 per cent of which is pelagic). However, much of the information presented in this chapter focuses on biodiversity of waters substantially deeper than 200 m. Many of the other regional divisions of Chapter 36 include treatments of shelf and slope biodiversity in continental-shelf and slope areas deeper than 200m. Moreover Chapters 42 and 45 on coldwater corals and vents and seeps, respectively, and 51 on canyons, seamounts and other specialized morphological habitat types address aspects of areas in greater detail. The estimates of global biodiversity of the deep sea in this chapter do include all biodiversity in waters and the seafloor below 200 m. However, in the other sections of this chapter redundancy with the other regional chapters is avoided, so that biodiversity of shelf, slope, reef, vents, and specialized habitats is assessed in the respective regional or thematic chapters.https://nsuworks.nova.edu/occ_facbooks/1050/thumbnail.jp

The effect of mud volcano activity on biodiversity at shallow to deep water mud volcanoes at the Moroccan Atlantic slope and in the Gulf of Cadiz

The newly discovered Larache mud volcano field at the Moroccan Atlantic slope (200 m - 700m water depth), and a deep water mud volcano field (1000 m - 1200 m water depth) in the Portuguese sector of the Gulf of Cadiz, have been investigated using side scan sonar, multibeam, video imagery, TV-guided grab, dredge and coring. At five mud volcanoes (Al Idrissi mv, Mercator mv, Gemini mv, Aveiro mv, and Captain Arutnyov mv) biodiversity was studied in relation to environmental factors.This study illustrated that the occurrence of mud volcanoes on the continental slope create new habitats and add to biodiversity. The study yielded the following results:The thickness of hemipelagic drape overlying mud breccias showed that all mud volcanoes have been active in the last 1600 years.Video imagery observations indicate an eastbound current over the Al Arraiche mud volcano field. At greater water depths this current becomes more variable.Faunal assemblages change with the sedimentary facies of the sea floor at each mud volcanoCurrents influence the distribution of trophic groups over the mud volcanoes. Populations of filter feeders are more dense on the upcurrent slope. On the downcurrent slope they are replaced by deposit feeders and scavengers.Faunal diversity and bioturbation increases at seep sitesAbundances of megafauna decreases with increasing water depth.The disturbance of the fauna by mud eruptions is small as periods inactivity are much larger than the time needed for recolonization. Seepage of fluids has a longer-lasting influence, resulting in a decrease of sessile filter feeders and burrows towards the summit of most mud volcanoes.The data were acquired during 2 consecutive surveys by the R/V Belgica (CADIPOR cruise) and the R/V Prof Logachev (TTR 12 cruise)

Record of anthropogenic impact on the Western Irish Sea mud belt

Six cores, geophysical data (multibeam bathymetry), surface grab samples and video photography were collected from the area of the Western Irish Sea Mud Belt (WISMB). These data were analysed to determine the radionuclide input from the Sellafield nuclear facility on the eastern (UK) seaboard of the Irish Sea, and subsequently to assess the influence of bottom trawling and bioturbation on the surface and near-surface sediments. Results show significant changes in the sedimentation and geochemical regime in the WISMB due to anthropogenic causes (bottom trawling and radionuclides derived from the power plant). These changes are consistent with the concept of the Anthropocene time period. Levels of anthropogenic radionuclides measured in two of the cores enabled construction of a chronology correlated with recorded values of discharge from the Sellafield facility. Excess 210Pb and the anthropogenic radionuclide 137Cs proved useful as stratigraphic marker tools. These radionuclide data also enabled quantification of the effects of trawling, which was visible on acoustic seabed maps. Bottom trawling has removed an estimated 20–50 cm of the upper seabed