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Marine Sites (marine + site)
Selected AbstractsReproductive cycle of female Brazilian codling, Urophycis brasiliensis (Kaup 1858), caught off the Uruguayan coastJOURNAL OF APPLIED ICHTHYOLOGY, Issue 2 2000By A. Acuña Between August 1993 and September 1995, aspects of reproduction of female Urophycis brasiliensis (Phycidae), a euryhaline species found in the Western Atlantic between 23° and 40° S, were studied. A total of 2500 specimens (23,60 cm; 113,2400 g) were obtained from artisanal fishermen at two locations on the Uruguayan coast: Piriápolis, influenced by the discharge of the Río de la Plata, and La Paloma, a marine site. The ovaries of 900 fish, analysed according to standard histological techniques, revealed eight maturity stages, including one virgin ovary obtained from the catch of a research vessel. The gonadosomatic index ranged from 0.13 to 8.7. Its maximum was determined in the autumn in La Paloma, whereas a shift towards the winter was observed in Piriápolis. In both capture areas, resting stage 2 was present in the samples throughout the year, reaching 67% of the total. At no time were hydrated ovaries observed. The histological cycle is described and compared with macroscopic features of the female gonad. Maturity stages determined in the field had to be confirmed by histological analysis in order to avoid erroneous classification. Although the two ports are only 150 km apart, data indicate different and extended reproductive periods, between June and December for Piriápolis, and March to May for La Paloma. Data indicate synchronous group spawning, possibly as a reproductive strategy in a highly variable environment. The results are compared with scarce information available on U. brasiliensis in its distribution area and data on other species of the same genus. [source] Metal concentrations, sperm motility, and RNA/DNA ratio in two echinoderm species from a highly contaminated fjord (the Sørfjord, Norway),ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 7 2008Ana I. Catarino Abstract The present study evaluated the effects of field metal contamination on sperm motility and the RNA/DNA ratio in echinoderms. Populations of Asterias rubens and Echinus acutus that occur naturally along a contamination gradient of sediments by cadmium, copper, lead, and zinc in a Norwegian fjord (the Sørfjord) were studied. Sperm motility, a measure of sperm quality, was quantified using a computer-assisted sperm analysis system. The RNA/DNA ratio, a measure of protein synthesis, was assessed by a one-dye (ethidium bromide)/one-enzyme (RNase), 96-well microplate fluorometric assay. Although both species accumulate metals at high concentrations, neither sperm motility parameters in A. rubens nor the RNA/DNA ratio in both species were affected. The Sørfjord is still one of the most metal-contaminated marine sites in Europe, but even so, populations of A. rubens and E. acutus are able to endure under these conditions. [source] Evolutionary divergence and possible incipient speciation in post-glacial populations of a cosmopolitan aquatic plantJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 1 2005G. Nies Abstract Habitat configuration is expected to have a major influence on genetic exchange and evolutionary divergence among populations. Aquatic organisms occur in two fundamentally different habitat types, the sea and freshwater lakes, making them excellent models to study the contrasting effects of continuity vs. isolation on genetic divergence. We compared the divergence in post-glacial populations of a cosmopolitan aquatic plant, the pondweed Potamogeton pectinatus that simultaneously occurs in freshwater lakes and coastal marine sites. Relative levels of gene flow were inferred in 12 lake and 14 Baltic Sea populations in northern Germany using nine highly polymorphic microsatellite markers developed for P. pectinatus. We found highly significant isolation-by-distance in both habitat types (P < 0.001). Genetic differentiation increased approximately 2.5-times faster among freshwater populations compared with those from the Baltic Sea. As different levels of genetic drift or population history cannot explain these differences, higher population connectivity in the sea relative to freshwater populations is the most likely source of contrasting evolutionary divergence. These findings are consistent with the notion that freshwater angiosperms are more conducive to allopatric speciation than their life-history counterparts in the sea, the relative species poor seagrasses. Surprisingly, population pairs from different habitat types revealed almost maximal genetic divergence expected for complete reproductive isolation, regardless of their respective geographical distance. Hence, the barrier to gene flow between lake and sea habitat types cannot be due to dispersal limitation. We may thus have identified a case of rapid incipient speciation in post-glacial populations of a widespread aquatic plant. [source] Distribution, sediment magnetism and geochemistry of the Saksunarvatn (10 180 ± 60 cal. yr BP) tephra in marine, lake, and terrestrial sediments, northwest IcelandJOURNAL OF QUATERNARY SCIENCE, Issue 8 2002Prof. John T. Andrews Abstract In 1997, seismic surveys in the troughs off northwest and north Iceland indicated the presence of a major, regional sub-bottom reflector that can be traced over large areas of the shelf. Cores taken in 1997, and later in 1999 on the IMAGES V cruise, penetrated through the reflector. In core MD99-2269 in Húnaflóaáll, this reflector is shown to be represented by a basaltic tephra with a geochemical signature and radiocarbon age correlative with the North Atlantic-wide Saksunarvatn tephra. We trace this tephra throughout northwest Iceland in a series of marine and lake cores, as well as in terrestrial sediments; it forms a layer 1 to 25 cm thick of fine- to medium-grained basaltic volcanic shards. The base of the tephra unit is always sharp but visual inspection and other measurements (carbonate and total organic carbon weight %) indicate a more diffuse upper boundary associated with bioturbation and with sediment reworking. Off northwest Iceland the Saksunarvatn tephra has distinct sediment magnetic properties. This is evident as a dramatic reduction in magnetic susceptibility, an increase in the frequency dependant magnetic susceptibility and ,hard' magnetisation in a ,0.1T IRM backfield. Geochemical analyses from 11 sites indicate a tholeiitic basalt composition, similar to the geochemistry of a tephra found in the Greenland ice-core that dates to 10 180 ± 60 cal. yr BP, and which was correlated with the 9000 14C yr BP Saksunarvatn tephra. We present accelerator mass spectrometry 14C dates from the marine sites, which indicate that the ocean reservoir correction is close to ca. 400 yr at 9000 14C yr BP off northwest Iceland. Copyright © 2002 John Wiley & Sons, Ltd. [source] Review: Biodegradation of tributyltins (organotins) by marine bacteriaAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 1 2003S. K. Dubey Abstract Many marine bacterial strains have an inherent capability to degrade toxic organotin compounds, especially tributyltins (TBTs), that enter into the environment in the form of insecticides, fungicides and antifouling paints as a result of anthropogenic and industrial activities. Significant degradation of these compounds in the ambient environment may take several years, and it is necessary to consider methods or strategies that can accelerate the degradation process. There have been few demonstrations of biological degradation of these organotin biocides exclusively in laboratory-scale experiments. Compared with the few bench-scale degradation processes, there are no reports of field-scale processes for TBT bioremediation, in spite of its serious environmental threat to non-target organisms in the aquatic environment. Implementation of field-scale biodegradation of TBT requires inputs from biology, hydrology, geology, chemistry and civil engineering. A framework is emerging that can be adapted to develop new processes for bioremediation of toxic environmental wastes. In the case of TBT bioremediation, this framework incorporates screening and identification of natural bacterial strains, determination of optimal conditions for growth of isolates and TBT degradation, establishment of new metabolic pathways involved in TBT degradation, identification, localization and cloning of genes involved in degradation and in TBT resistance, development of suitable microbial strains using genetic manipulation techniques for practical applications and optimization of practical engineering processes for bioremediation of organotin-contaminated sites. The present review mainly addresses the aspect of TBT biodegradation with special reference to environmental sources of TBT, chemical structure and biological activity, resistant and degrading bacterial strains, possible mechanisms of resistance and degradation and the genetic and biochemical basis of TBT degradation and resistance. It also evaluates the feasibility and potential of natural and genetically modified TBT-degrading bacterial strains in field-scale experiments to bioremediate TBT-contaminated marine sites, and makes recommendations for more intensive and focused research in the area of TBT bioremediation mediated by marine bacterial strains. Copyright © 2002 John Wiley & Sons, Ltd. [source] Key biodiversity areas as globally significant target sites for the conservation of marine biological diversityAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 6 2008Graham J. Edgar Abstract 1.Recent approaches to the planning of marine protected area (MPA) networks for biodiversity conservation often stress the need for a representative coverage of habitat types while aiming to minimize impacts on resource users. As typified by planning for the Australian South-east Marine Region, this strategy can be manipulated by political processes, with consequent biased siting of MPAs. Networks thus created frequently possess relatively low value for biodiversity conservation, despite significant costs in establishment and maintenance. 2.Such biases can be minimized through application of the data-driven and species-based concept of key biodiversity areas (KBAs). 3.By mapping locations of threatened species and populations that are highly aggregated in time or space, the KBA process allows marine sites of global biodiversity significance to be systematically identified as priority conservation targets. Here, the value of KBAs for marine conservation planning is outlined, and guidelines and provisional criteria for their application provided. Copyright © 2008 John Wiley & Sons, Ltd. [source] | ||||||||||