Showing papers by "Scottish Association for Marine Science published in 2000"

Continental slope and deep-sea fisheries: implications for a fragile ecosystem

Abstract: Koslow, J. A., Boehlert, G. W., Gordon, J. D. M., Haedrich, R. L., Lorance, P., andParin, N. 2000. Continental slope and deep-sea fisheries: implications for a fragileecosystem. – ICES Journal of Marine Science, 57: 548–557.Exploited deepwater (>500 m) species generally exhibit clear ‘‘K-selected’’ life-history characteristics markedly different from most shelf species: extreme longevity,late age of maturity, slow growth, and low fecundity. Many also aggregate onrestricted topographic features such as seamounts, and as a consequence are notablyunproductive, highly vulnerable to overfishing, and have potentially little resilienceto overexploitation. Since 1964, deepwater fisheries have contributed 800 000–1 000 000 t annually to global marine fish landings. Underlying this apparent overallstability is the ‘‘boom and bust’’ cycle that has characterized many individualfisheries. The accumulated biomass of previously unfished stocks is typically fisheddown, often within 5–10 years, to the point of commercial extinction or very lowlevels. Most deepwater stocks are today overfished or even depleted. Depletion ofspecies from deep-sea environments that dominate mid to upper trophic levels mayhave long-term ecological implications, but the risks of reduced stock size and agestructure to population viability, the potential for species replacement, and theimpacts on prey and predator populations are not generally known. However, trawlfisheries have been shown to have potentially severe impacts on the benthic fauna ofseamounts, where these fish aggregate. This fauna, dominated by suspension feeders,such as corals, is typically restricted to the seamount environment and is character-ized by high levels of endemism, which suggests limited reproductive dispersal. Theability of the benthic community to recover, following its removal by trawling, is notknown.

Macrobenthic community structure within and beneath the oxygen minimum zone, NW Arabian Sea

Abstract: Investigations of macrobenthos were carried out within and beneath the oxygen minimum zone (OMZ, E[S 100 ], H′ and J′ across the transect; grain size and % TOC did not yield significant regressions. Pigments, assumed to reflect food availability and possibly oxygen effects on organic matter preservation, were negatively correlated with species richness and evenness, and positively correlated with dominance. The reverse was true for water depth. Macrobenthic patterns of calcification and lifestyle within the Oman margin OMZ (0.13–0.3 ml l−1) match the dysaerobic biofacies of paleo-environmental reconstruction models.

Impact of nonlinear waves on the dissipation of internal tidal energy at a shelf break

Abstract: The vertical and temporal structure of the dissipation of turbulent kinetic energy within the internal tide at a location 5 km shoreward of the shelf break on the Malin Shelf has been determined using a combination of the free-falling light yo-yo profiler and acoustic doppler current profilers. Two distinct internal wave regimes were encountered: period I in which large-amplitude high-frequency nonlinear internal waves (NIWs) occurred (around neap tides) and period II in which the internal wave spectral continuum was not dominated by any particular frequency band (around spring tides). Empirical orthogonal function analysis shows that for the low-frequency waves, 76% of the variance was described by mode 1, rising to 95% for the high-frequency waves. During period I the dissipation and vertical mixing were characterized by the NIWs, and 70% of the dissipation occurred in the bottom boundary layer. During period II the depth-integrated dissipation was more evenly distributed throughout the tidal cycle, whereas vertical mixing was greatly enhanced during a single hour long episode of elevated thermocline dissipation coincident with weakened stratification. During both periods I and II ∼30% of the total measured dissipation occurred within the thermocline when averaged over 12.4 hours; the remainder occurred within the bottom boundary layer(BBL). Tidal average values for depth-integrated dissipation and vertical eddy diffusivity for period I (II) were 1.1×10−2 W m−2 (4.0×10−2 W m−2) and 5 cm2 s−1 (12 cm2 s−1), respectively. Decay rates and internal damping are discussed, and vertical heat fluxes are estimated. Observed dissipation rates are compared with a simple model for BBL dissipation.

Variations in bioturbation across the oxygen minimum zone in the northwest Arabian Sea

Abstract: Oxygen minimum zones are expected to alter substantially the nature, rates and depths of bioturbation along continental margins, yet these effects remain poorly studied. Using excess 210 Pb profiles, sediment X-radiography and box-core samples for macrofauna, we examined bioturbation processes at six stations (400, 700, 850, 1000, 1250 and 3400 m deep) along a transect across the oxygen minimum zone (OMZ) on the Oman margin. Bottom-water oxygen concentrations ranged from ∼0.13 ml l−1 at 400 m to ∼2.99 ml l−1 at 3400 m. 210 Pb mixed-layer depth and bioturbation intensity (Db) exhibited high within-station variance, and means did not differ significantly among stations. However, the mean mixed-layer depth (4.6 cm) for pooled OMZ stations (400–1000 m depths, 0.13–0.27 ml l−1 bottom-water oxygen) was half that for stations from similar water depths along well-oxygenated Atlantic and Pacific slopes (11.1 cm), suggesting that oxygen stress reduced 210 Pb mixing depth on the Oman margin. Modal burrow diameter and the diversity of burrow types at a station were highly correlated with bottom-water oxygen concentration from the edge to the core of the Oman OMZ (Spearman's rho⩾0.89, p⩽0.02), suggesting that these parameters are useful proxies for bottom-water oxygen concentrations under dysaerobic conditions. In contrast, neither the maximum diameter and nor the maximum penetration depth of open burrows exhibited oxygen-related patterns along the transect. Reduced 210 Pb mixing depth within the Oman-margin OMZ appeared to result from a predominance of surface-deposit feeders and tube builders within this zone, rather than from simple changes in horizontal or vertical distributions of macrofaunal abundance or biomass. The number of burrow types per station was highly correlated with macrofaunal species diversity, suggesting that burrow diversity may be a good proxy for species diversity in paleo-dysaerobic assemblages. We conclude that bottom-water oxygen concentrations of 0.13–0.27 ml l−1 substantially alter a number of bioturbation parameters of importance to diagenetic and biofacies models for continental margins.

Benthic carbon mineralization in a high-Arctic sound (Young Sound, NE-Greenland)

Abstract: Benthic carbon mineralization was investigated along a depth transect across a sound in the high Arctic. Aerobic mineralization accounted for approximately 30% of the total degradation. Anaerobic degradation, responsible for the remaining 70%, was dominated by sulfate- and iron res- piration, while denitrification and manganese respiration were of marginal importance. The total benthic degradation rate exhibited a rapidly attenuating exponential decline with increasing water depth. Permanent carbon burial accounted for approximately 50% of the total degradation rate, and was comparable to estimates from similar settings at lower latitudes. At the shallow stations, benthic infauna stimulated the benthic oxygen exchange by a factor of 1.5 to 3 relative to molecular diffusion. However, the estimated metabolic activity of the fauna itself accounted for <10% of total benthic degradation. From the rates of benthic degradation, permanent burial, pelagic primary production, and sedimentation of organic carbon, a budget for the pelagic-benthic coupling for outer Young Sound was established. Pelagic production accounted for only a minor fraction of the carbon required by the benthic community, and δ 13 C values suggested that terrestric carbon inputs were significant. However, the budget also indicated that additional sources of labile organic carbon (ice-algae, ben- thic microphytes and oceanic inputs) were important. During July, the time of the summer bloom, 36% of the sedimenting organic material was either degraded or buried. The remainder fueled the community respiration during the long, non-productive, winter.

Seabed photography, environmental assessment and evidence for deep-water trawling on the continental margin west of the Hebrides

Abstract: A photographic survey in 1998 of the seabed along depth transects from 700 to 1300 m across the N.E. Atlantic continental slope off north-west Scotland shows clear depth-related change in sediment type and megabenthic community in an environment where biological communities and species distributions are poorly known. Small-scale features, such as trawl marks and dense fields of xenophyophores, were resolved that may have remained unknown using conventional sampling or lower resolution imaging techniques. Because xenophyophores accumulate barite, a constituent of some drilling muds, their local-scale occurrences will be important to baseline environmental survey prior to hydrocarbon prospecting in deep water. Our results indicate that deep-sea trawling is physically impacting the seabed to depths of more than 1000 m. The persistence and biological consequence of this impact is unknown, but may depend on sediment type and natural physical disturbance. Comparison with similar seabed photographs taken from a neighbouring area in 1988, which show a high incidence of trawl marks, indicates that such impacts have been taking place over at least 10 years.

A literature review of studies on fish egg mortality: implications for the estimation of spawning stock biomass by the annual egg production method

Abstract: (Funded under MAFF project code MF0426: Fish egg development and mortality studies in the Irish Sea) LOWESTOFT 2000

Morphological responses of macrobenthic polychaetes to low oxygen on the Oman continental slope, NW Arabian Sea

Abstract: Morphological adaptation to low dissolved oxygen consisting of enlarged respiratory surface area is described in polychaete species belonging to the family Spionidae from the Oman margin where the oxygen minimum zone impinges on the continental slope. Similar adaptation is suggested for species in the family Cossuridae. Such morphological adaptation apparently has not been previously recorded among polychaetes living in hypoxic conditions. The response consists of enlargement in size and branching of the branchiae relative to similar species living in normal levels of dissolved oxygen. Specimens were examined in benthic samples from different depths along a transect through the oxygen minimum zone. There was a highly significant trend shown to increasing respiratory area relative to body size in two undescribed spionid species with decreasing depth and oxygen within the OMZ. Yet the size and number of branchiae are often used as taxonomic characters. These within-species differences in size and number of branchiae may be a direct response by the phenotype to intensity of hypoxia. The alternative explanations are that they either reflect a pattern of differential post-settlement selection among a highly variable genotype, or represent early genetic differentiation among depth-isolated sub-populations.

Patterns in deep-sea macrobenthos at the continental margin: standing crop, diversity and faunal change on the continental slope off Scotland

Abstract: Depth-related patterns of macrobenthic community structure and composition have been studied from box-core samples from the Scottish continental slope where deep-sea trawling and oil exploration are becoming increasingly important. There is a strong pattern of declining biomass and faunal abundance with increasing depth, but results also indicate reduced biomass and numbers of macrobenthos in the shallowest samples from just below the shelf edge where there are coarse sediments and a regime of strong bottom currents. There is also reduced species diversity at the shallowest stations, probably caused by hydrodynamic disturbance, but no clear mid-slope peak in species diversity as described from the northwest Atlantic. Taxonomic composition of the macrobenthic community shows most change between about 1000 and 1200 m, expressed as a major dichotomy in multivariate analysis by cluster analysis and ordination. It also shows up as a step-like increase in the rate of accumulation of new macrofaunal species. This corresponds to a change in hydrodynamic regime, from a seabed rich in suspension- and interface-feeding epifauna, to one where biogenic traces from large, burrowing deposit feeders are well developed, and visible epifauna rare in seabed photographs. It also corresponds to the depth zone where earlier study of megafaunal echinoderms in trawl and epibenthic sled samples also shows a clear peak in across-slope rate of change in faunal composition.

The abundance of heterotrophic protists associated with intertidal seaweeds

Abstract: Seaweeds have long been known to support abundant populations of bacteria so it is surprising that few studies have considered the abundance of heterotrophic protists on seaweed surfaces. A year-long study was conducted to investigate the numbers of heterotrophic protists on undamaged and damaged tissue of a number of intertidal species of seaweed. Generally, amoebae and flagellates numbered less than 20 cells cm −2 on undamaged seaweed tissue but were found in greater numbers (more than 20 cm −2 ) on damaged tissue. Ciliates were around 1 or 2 cells cm −2 on undamaged seaweeds and between 1 and 5 cm −2 on damaged tissue. Numbers of heterotrophic dinoflagellates and heterotrophic diatoms were similar to those of ciliates in late summer and autumn when seaweeds were producing increased amounts of dissolved organic carbon. By assuming that ‘ true ’ surface protists inhabited the thin surface film of water on seaweeds, comparisons were drawn with the numbers of protists in nearby open waters. After using appropriate conversion factors, both amoebae and flagellates were more abundant in the surface film (per ml) than in the open water. In particular, surface amoebae averaged around 1800 cells ml −1 but only reached around 19 cells ml −1 in open water. The results are discussed in relation to the various sources of nutrition available to heterotrophic protists on macroalgae. The high numbers of amoebae suggest that they are the major micropredators of bacteria on seaweed surfaces.

The reproductive cycle of the sea urchin Psammechinus miliaris (Echinodermata: Echinoidea) in a Scottish sea loch

Abstract: The sea urchin Psammechinus miliaris was sampled at monthly intervals from two replicate sites at contrasting locations (littoral and subtidal habitats) on the west coast of Scotland. Samples were collected from November 1995 to October 1997. A study of gonad development showed a clearly defined annual cycle of gametogenesis with a single spawning period. Gonad indices (GIs) varied between locations, between sites at the same location and between study years. Gonad indices were maximal prior to the onset of the spawning period in June and July. Ripe gametes were shed by dissected urchins from June to September in 1996 and June to August in 1997 coinciding with the time of year when the gonad colour was best in terms of what is desired in the market place. Over winter the GIs were very low and gonads became very dark in colour. Higher summer GIs in the urchins from one littoral site suggested that the urchins there had a seasonal influx of a more nutritious or more abundant food resource. Histological determination of the reproductive state showed that for these food-limited populations high GIs do equate with the spawning period. The gametogenic cycle fits the six stage pattern described for other echinoid species. In females oocytes of various developmental stages were present throughout the annual cycle. Recruitment to the littoral location was monitored over two seasons by quantifying the number of urchins with a test diameter < 5 mm appearing in the population. Recruitment appeared variable between sites and between seasons suggesting that the collection of juveniles resulting from natural settlement may not be a reliable alternative to hatchery produced spat. Although P miliaris has commercial potential when in cultivation, this study provided no evidence of an opportunity for a commercial fishery.

Genetic and morphometric comparisons of squat lobster, Munidopsis scobina (Decapoda: Anomura: Galatheidae) populations, with notes on the phylogeny of the genus Munidopsis

Abstract: Specimens of the galatheid Munidopsis scobina were collected from two stations on the continental slope off Oman, at depths of 900 and 1000 m, using an Agassiz trawl. Starch gel electrophoresis, across 10 enzyme loci, was carried out on 427 specimens. Genetic variability was calculated for both populations using a number of parameters. F-statistics were used to estimate genetic variance within (FIS) and between (FST) populations. Significant deviations from Hardy-Weinberg expectations were detected at one locus (Gotb). Analyses of FIS revealed significant differences from zero at Gotb and Pgm, as a result of heterozygote deficiency. No relationship was observed between size of individuals and genotype. The number of genetically effective migrants per deme per generation (Nem) was calculated using both FST and private alleles methods. Nem values were theoretically sufficient to offset the effects of genetic drift. Additional morphometric analyses were carried out on Munidopsis scobina from the two populations. Individuals were sexed (n=2476 individuals) and ten parameters measured (n=1238). All specimens were examined for parasites (either bopyrid isopod or rhizocephalan). Significant male-biased sex ratios were observed in both populations (p<0.01). In addition, significant differences in size-frequency distributions (p<0.01) were recorded both within sites between sexes, and within sexes between sites; possibly related to a size-dependent response to hypoxia. Significant differences also were observed in mean cheliped length between sexes (p<0.01), potentially indicating that male M. scobina exhibit agonistic behaviour. The genetic relationships of Munidopsis scobina to four other species of Munidopsis (M. crassa, M. parfaiti, M. spinihirsuta and M. subsquamosa) and the confamilial Galathea squamifera were also examined using allozyme loci. Within the genus Munidopsis, pairwise comparisons of genetic identity were within the normal range expected for congeneric species. Comparisons between G. squamifera and Munidopsis spp. were within the range expected for confamilial genera.

Community structure of the benthos in Scottish Sea-lochs. IV. Multivariate spatial pattern

Abstract: Most studies of spatial patterns of invertebrates in soft sediments have concentrated on populations of individual species. Those that examined patterns in communities have tended to employ categorical analytical techniques. Using macrofaunal abundance data from van Veen grab samples collected 20 to 100 m apart in known spatial arrangements from Scottish sea-lochs, the relationships between patterns in macrobenthic species composition and distances between samples were explored using matrix correlations in a non-parametric framework. Using a simple definition of spatial structure, i.e. that intersample distances are monotonically correlated with intersample species-similarity, spatial structure at each of seven stations was assessed using non-parametric Mantel tests based on rank-correlations. Changes in community structure were positively correlated with distance at all sites in Loch Etive, on both current-swept muddy sands and soft deep muds. Different components of the macrobenthos contributed to spatial pattern at each site. Simple spatial structure was also detectable at a muddy-sand site in Loch Creran, but neither on soft mud, nor at the soft mud site in the Firth of Lorne. The concept of rank-correlograms was introduced. These were used to examine the extent and form of spatial structure in different components of the macrobenthos at each site. Relationships between similarity and distance were neither simple nor consistent. Results were compared to previous studies which used the same data, and it was concluded that studies carried out at a particular scale, or on a particular component of the benthos, are unlikely to be successful in predicting spatial relationships at other scales or for other components of the benthos. Correlational rather than categorical analyses are recommended for exploratory studies of spatial relationships in the benthos. Analyses of the spatial structure at these seven sea-loch sites suggests that by ensuring that samples are at least 40 m apart an investigator is unlikely to underestimate variability or otherwise invalidate statistical analyses based on the use of the samples as replicates. Spacing samples up to 100 m apart may increase variability estimates, further reducing the chance of concluding that a difference exists when one does not.

Spatial variations in nutrient utilization, production and diagenesis in the sediments of a coastal upwelling regime (NW Africa): Implications for the paleoceanographic record

Abstract: A biogeochemical study of recent (multicores) sediments of the northwest African slope was undertaken to understand how the sediment composition varies with respect to the location of core sites relative to the centers of coastal upwelling, and how this has affected the palaeoceanographic record. Sedimentary organic carbon contents are inversely correlated with the nitrogen isotopic composition (δ 15 N), high C organic concentrations and low δ 15 N occurring at proximal (shallow) sites and the opposite at distal (deep) ones. These spatial differences are interpreted to result from higher relative nutrient utilization and a decrease in production as waters are advected offshore from the zone of upwelling. Highest C organic contents also correlate positively with highest concentrations of redox-sensitive elements (U, Mo and S) that are fixed diagenetically in the sediments. These results suggest that the sedimentary regime at a fixed position depends on the spatial location of the productive areas relatively to a given core site. Downcore records of Zr/Al, Ti/Al, mean grain size of the terrigenous fraction, δ 15 N, C organic , biogenic Ba, U, Mo and sulfur at a single site on the slope are interpreted to reflect glacial-interglacial changes in the core location relative to the coastline (sea-level effect), and hence changes in production as the area of coastal upwelling moved on- and offshore as sea-level changed, as well as undoubtedly changes in upwelling intensity through wind forcing. Further studies are needed to fully understand the interrelationships of all these processes, which are required for building more reliable paleoceanographic-paleoclimatic records.

Reproduction, dispersal and settlement of the bathyal ophiuroid Ophiocten gracilis in the NE Atlantic Ocean

Abstract: Ophiocten gracilis is an ophiuroid found at bathyal depths in the North Atlantic Ocean. The adults show strong seasonal reproduction, with an ophiopluteus in the surface plankton. Settling postlarvae were collected in sediment traps moored at 1000 and 1400 m depth in the NE Atlantic during Julian Days 142 to 212 (May to July) in 1996. During this period, growth of postlarvae in the traps was linear and the diet consisted of phytodetritus and foraminifera. Experiments suggest that postlarvae sink at rates of up to 500 m dm1, although this may well be slower in the natural environment. The high fecundity, seasonality and high population density resulted in high fertilization success, and many of the offspring were advected outside the normal adult range, where they were able to settle but did not survive to adulthood.

Size-related aspects of arm damage, tissue mechanics, and autotomy in the starfish Asterias rubens

Abstract: Arm damage is a widely reported but superficially investigated aspect of the biology of the starfish Asterias rubens L. In the present study, the incidence of arm damage was surveyed in populations of A. rubens at two sites in the Firth of Clyde, Scotland, and three sites in Gullmarsfjorden, Sweden. The mean (±SD) incidence across all sites of individuals with basal arm damage (resulting from detachment at the basal autotomy plane) was 19.69 ± 8.86%, the incidence of those with distal arm damage (resulting from amputation at more distal levels) was 7.74 ± 10.01%. The mean incidence of arms with basal damage was 5.28 ± 4.12%, of those with distal damage 1.83 ± 2.45%. There was a significant negative correlation between size and the incidence of basal damage at all but one site, but no significant correlation between size and distal damage at any site. Mechanical tests on specimens of the aboral body wall from the basal region of the arm (which included the autotomy plane) and from a more distal region revealed that with increasing body size there was a significant increase in yield stress, ultimate stress and Young's modulus (stiffness) but no significant change in yield strain and ultimate strain. There was no significant difference between the relationships for basal and distal specimens. It is hypothesised that in larger individuals increased mechanical toughness replaces autotomy as an effective antipredator strategy. Using two methods to induce autotomy, a significant positive correlation between size and the delay between the onset of stimulation and arm detachment was found; this may represent a size-related decline in the efficiency of the autotomy mechanism through the relaxation of selection pressure. Since size is an unreliable indicator of age in A. rubens, the trends identified herein can be interpreted only tentatively as age-associated phenomena.

Comparisons of fatty acid and stable isotope ratios in symbiotic and non-symbiotic brittlestars from Oban Bay, Scotland

Abstract: The bed-forming brittlestars Ophiothrix fragilis, Ophiocomina nigra and Amphiura chiajei from Oban Bay, Scotland were studied using methods previously employed to study chemoautotrophic symbioses. Ophiothrix fragilis and A. chiajei both contain symbiotic bacteria (SCB) while Ophiocomina nigra is non-symbiotic. Samples were taken of Ophiothrix fragilis at approximately two-week intervals for one year. Symbiotic bacteria numbers were determined by direct counting of homogenates of the arms of 50 individual brittlestars. Water samples were analysed for chlorophyll content. Stable isotope ratios for carbon and nitrogen were determined for each homogenate sample. Regular SCB counts were made on the infaunal brittlestar A. chiajei. Homogenate samples of Ophiothrix fragilis, A. chiajei and the non-symbiotic Ophiocomina nigra were analysed to produce fatty acid profiles for each species. Symbiotic bacteria count varied by up to one order of magnitude in both Ophiothrix fragilis and A. chiajei with no evidence of seasonality in this variation. Symbiotic bacteria number was inversely correlated with δ 15 N but no relationship was established with δ 13 C. 16:1ω7 and 18:1.ω7 fatty acids were used as putative bacterial markers. Both symbiotic species had higher percentages of 16:1ω7 than the non-symbiotic Ophiocomina nigra. However, only Ophiothrix fragilis appeared to receive appreciable quantities of 18:1ω7 from its SCB. The SCB are heterotrophic and may contribute to the nitrogen budget of the host. The two symbiotic species studied here derive the bulk of their nutrition from conventional feeding but SCB make significant, additional contributions.

Video-assisted grabbing: a minimally destructive method of sampling azooxanthellate coral banks

Abstract: Traditional techniques used to sample azooxanthellate coral banks by dredge and trawl cause extensive impact to both the corals and surrounding seabed. Modern sampling techniques using submersibles and remotely operated vehicles cause very little or no damage, but are expensive and require specialized vessels. Here we describe a combination of video camera and benthic grab for sampling azooxanthellate corals and test this method on a Lophelia pertusa bank in Osterfjorden, western Norway. The video-assisted grab was successfully used both for locating and sampling L. pertusa. This method can largely replace the use of traditional, more destructive dredging and trawling techniques for sampling azooxanthellate corals.

Benthic processes in the deep Arabian Sea: introduction and overview

Abstract: The Arabian Sea in the north-western Indian Ocean is a relatively small but biogeochemically active area of the world ocean. As a result of the monsoon dynamics and consequent high material #ows the region has been thought to have global signi"cance in terms of biogeochemical #uxes (Law and Owens, 1991; Owens et al., 1991). The seasonal reversal of winds leads to strong seasonal upwelling of nutrientrich water from the depths along the narrow continental shelf resulting in high surface productivity and high export particle #ux from the euphotic zone (Quasim, 1982; Sen Gupta and Naqvi, 1984; Nair et al., 1989). However, our understanding of the biological oceanography of the Arabian Sea, particularly its benthic biology, has developed rather intermittently because the region has been far away from the areas of main research emphasis. Benthic fauna in deep water was collected in the Arabian Sea during the voyages of the Indian Marine Survey vessels `Investigator Ia and `Investigator IIa between 1885 and 1925. The discovery of what was considered a more or less azoic zone on the sea bed between about 100}1200 m depth along the continental margin of Arabia is associated with the trawling and dredging work of the Egyptian research vessel `Mabahissa during the John Murray Expedition of 1933}1934 (Sewell, 1934a,b). Taxonomic studies of the fauna collected underlined the taxonomic and zoogeographic importance of the area. But the realisation of the connection between the sediment samples smelling strongly of hydrogen sulphide, along with the apparent absence of megabenthos and the

Environmental impacts of aquaculture.

Abstract: The environmental impacts of marine fish cage culture Freshwater finfish cage culture Ecological effects of shellfish cultivation Environmental effects of warm water culture in ponds / lagoons Tank culture and recirculating systems Genetic impacts of aquaculture Modelling impacts Aquaculture in the age of integrated coastal management (ICM) Sustainability of aquaculture References Index.