Magnitude and extent of sediment toxicity in selected estuaries of South Carolina and Georgia

Toxic chemicals can enter the marine environment through numerous routes: stormwater runoff, industrial point source discharges, municipal wastewater discharges, atmospheric deposition, accidental spills, illegal dumping, pesticide applications and agricultural practices. Once they enter a receiving system, toxicants often become bound to suspended particles and increase in density sufficiently to sink to the bottom. Sediments are one of the major repositories of contaminants in aquatic envronments. Furthermore, if they become sufficiently contaminated sediments can act as sources of toxicants to important biota. Sediment quality data are direct indicators of the health of coastal aquatic habitats. Sediment quality investigations conducted by the National Oceanic and Atmospheric Administration (NOAA) and others have indicated that toxic chemicals are found in the sediments and biota of some estuaries in South Carolina and Georgia (NOAA, 1992). This report documents the toxicity of sediments collected within five selected estuaries: Savannah River, Winyah Bay, Charleston Harbor, St. Simons Sound, and Leadenwah Creek (Figure 1). (PDF contains 292 pages)

Genetic engineering of microorganisms: free release into the environment

Genetic engineering now makes possible the insertion of DNA from many organisms into other prokaryotic, eukaryotic and viral hosts. This technology has been used to construct a variety of such genetically engineered microorganisms (GEMs). The possibility of accidental or deliberate release of GEMs into the natural environment has recently raised much public concern. The prospect of deliberate release of these microorganisms has prompted an increased need to understand the processes of survival, expression, transfer and rearrangement of recombinant DNA molecules in microbial communities. The methodology which is being developed to investigate these processes will greatly enhance our ability to study microbial population ecology.

Biodiversity in drinking water distribution systems:a brief review

In drinking water distribution systems, three groups of living organisms are usually found in the biofilm and circulating water: heterotrophic bacteria, free-living protozoa, and macro-invertebrates. Indirect evidence suggests that protozoa grazing in distribution systems can partially eliminate biomass production and accidental microbiological pollution. This paper examines the biodiversit in drinking water distribution systems.

Les macrophytes aquatiques des berges lagunaires

This synthetic article describes the composition and organization of vegetations colonizing the Ebrié lagoon banks and provides original data on the recent evolution of this association consecutively to the accidental introduction of 2 new species of floating macrophytes (Salvinia molesta and Eichhornia crassipes).

Comparative feeding ecology of two elasmobranch species, Squalus blainville and Scyliorhinus canicula, off the coast of Portugal

The small-spotted catshark (Scyliorhinus canicula) (Linnaeus, 1758) and the longnose spurdog (Squalus blainville) (Risso, 1826) are two species occurring in the European and western African continental shelves with a wide geographical distribution. In this study, the diet of S. blainville and S. canicula off the Portuguese western Atlantic coast was investigated in 2006 by collecting monthly samples of these two species from local fishing vessels. In the stomachs of both species, crustaceans and teleosts were the dominant prey items, and molluscs, polychaetes, echinoderms, and sipunculids were found in lower abundance. In S. canicula, urochordate and chondrichthyan species were also observed in stomachs and were classified as accidental prey items. Scyliorhinus canicula consumed a broader group of prey items than did S. blainville. A significant diet overlap was observed, despite both species occupying different depth ranges over the continental shelf. Scyliorhinus canicula exhibited a consistency in diet composition among seasons, sexes, and maturity stages. Nonetheless, for both adults and juveniles, an increase in relative abundance of teleosts in the diet was observed in the spring and summer. This study provides evidence of the importance of S. canicula and S. blainville as benthic and pelagic predators along the western Atlantic coast.

Comparison of echogram measurements against data expectations and assumptions for distinguishing seafloor substrates

Defining types of seafloor substrate and relating them to the distribution of fish and invertebrates is an important but difficult goal. An examination of the processing steps of a commercial acoustics analyzing software program, as well as the data values produced by the proprietary first echo measurements, revealed potential benef its and drawbacks for distinguishing acoustically distinct seafloor substrates. The positive aspects were convenient processing steps such as gain adjustment, accurate bottom picking, ease of bad data exclusion, and the ability to average across successive pings in order to increase the signal-to-noise ratio. A noteworthy drawback with the processing was the potential for accidental inclusion of a second echo as if it were part of the first echo. Detailed examination of the echogram measurements quantified the amount of collinearity, revealed the lack of standardization (subtraction of mean, division by standard deviation) before principal components analysis (PCA), and showed correlations of individual echogram measurements with depth and seafloor slope. Despite the facility of the software, these previously unknown processing pitfalls and echogram measurement characteristics may have created data artifacts that generated user-derived substrate classifications, rather than actual seafloor substrate types.

Trawling Operations and South African (Cape) Fur Seals, Arctocephalus pusillus pusillus

South African (Cape) fur seals, Arctocephalus pusillus pusillus, interact with the South African trawl fisheries-offshore demersal, inshore demersal, and midwater fisheries. These interactions take thef ollowing forms: Seals take or damage netted fish, on particular vessels they become caught in the propeller, seals drown in the nets, live seals come aboard and may be killed. Except in specific cases of seals damaging particular trawler propellers, interactions result in little cost to the offshore and midwater trawl fisheries. For the inshore fishery, seals damage fish in the net at an estimated cost in excess of R69, 728 (US$18,827) per year, but this is negligible (0.3%) in terms ofthe value of the fishery. Seal mortality is mainly caused by drowning in trawl nets and ranges from 2,524 to 3,636 seals of both sexes per year. Between 312 and 567 seals are deliberately killed annually, but this most likely takes place only when caught and they enter the area below deck, where they are difficult to remove, and pose a potential threat to crew safety. Overall, seal mortality during trawling operations is negligible (0.4-0.6%) in terms of the feeding population of seals in South Africa.

Marine fish assemblages associated with fish aggregating devices (FADs): effects of fish removal, FAD size, fouling communities, and prior recruits

Fishes are widely known to aggregate around floating objects, including flotsam and fish aggregating devices (FADs).The numbers and diversity of juvenile fishes that associated with floating objects in the nearshore waters of the eastern tropical Pacific were recording by using FADs as an experimental tool. The effects of fish removal, FAD size, and the presence or absence of a fouling community at the FAD over a period of days, and the presence of prior recruits over a period of hours were evaluated by using a series of experiments. The removal of FAD-associated fish assemblages had a significant effect on the number of the dominant species (Abudefduf troschelii) in the following day’s assemblage compared to FADs where the previous day’s assemblage was undisturbed; there was no experimental effect on combined species totals. Fishes do, however, discriminate among floating objects, forming larger, more species-rich assemblages around large FADs compared to small ones. Fishes also formed larger assemblages around FADs possessing a fouling biota versus FADs without a fouling biota, although this effect was also closely tied to temporal factors. FADs enriched with fish accumulated additional recruits more quickly than FADs that were not enriched with fish and therefore the presence of prior recruits had a strong, positive effect on subsequent recruitment. These results suggest that fish recruitment to floating objects is deliberate rather than haphazard or accidental and they sup-port the hypothesis that flotsam plays a role in the interrelationship between environment and some juvenile fishes. These results are relevant to the use of FADs for fisheries, but emphasize that further research is necessary for applied interests.

Un alga japonesa en la costa patagónica

En diciembre de 1992, a varios metros de profundidad y adheridos a los pilotes del muelle Almirante Storni de Puerto Madryn (Prov. Chubut, Argentina), se observaron algunos ejemplares de un alga de gran tamaño no registrada entre la flora marina argentina. Se trataba de Undaria pinnatifida, una especie originaria de las costas de Japón, que arribó presumiblemente en forma accidental, trasladada por barcos. Progresivamente esta especie se fue dispersando a lo largo de las costas de la Patagonia Argentina, con indeseables efectos ambientales, sociales y económicos. Se incluye información sobre las características del alga, su adaptación a diversas condiciones ambientales, su dispersión mundial, el impacto ambiental en la región, además de un glosario y lecturas sugeridas.

The present-day fishery of the Uganda waters of Lake Victoria

The Uganda waters of Lake Victoria comprise an area of 28,500 square kilometres with a shore line of 2,380 kilometres extending from the Uganda/Tanzania border in the west to the Uganda/Kenya border in the east. A large part of the Uganda waters of the lake is less than 60 metres deep, waters deeper than 60 metres being on the eastern side of the lake. Thus the Uganda part of the lake is tilted towards the east. A number of rivers drain into the lake from the north and the River Nile flows out of the lake towards the Mediterranean Sea. The Ssese, Kome, Buvuma and Busoga Islands form a very distinctive feature of the lake. These are perhaps the remaining high hills which survived the drowning of the northern valleys during the formation of the lake. In fact, in T. P. O'Brien's book 'The Prehistoric Uganda Protectorate (1939)', Solmon gives a critical summary of the work on the formation of Lake Victoria and shows that the northern part of the lake has numerous drowned valleys, a feature which provides varying habitats for particular species of fish and which may have an effect on the species composition reflected in the catches in different areas along the northern shore of the lake. It is interesting to note that although Lake Victoria as a whole has a number of rivers draining into it, Halbfass (1923) calculated and found that 76 per cent of the water entering the lake is precipitation on the lake surface.