Chris Frid

Abnormalities in the reproductive health of flounder Platichthys flesus exposed to effluent from a sewage treatment works

A large number of substances in daily use are now known to mimic the female sex hormone oestrogen. These include DDT, some PCBs, components of food packaging materials and certain alkylphenolic substances which may arise from alkylphenol polyethoxylates used in detergents, paints and cosmetics. Indicators of reproductive health including gonad morphology, hepatosomatic index (HSI) and serum levels of the egg protein vitellogenin (VTG) were determined for wild populations of the flounder, Platichthys flesus. Fish were obtained from three sites in northern England; the Solway Firth which receives only low levels of sewage effluent and two sites in the Tyne Estuary which receives effluent from a major sewage treatment works and a number of industrial discharges. Four lines of evidence suggest that the reproductive health of flounder is being influenced by exposure to oestrogenic substances. 1. Male fish with serum containing VTG, a reliable bio-indicator of oestrogen exposure, were recorded from all the sites studied. Frequency of occurrence was lowest (20%) in the Solway population and reached 60% at one of the sites in the Tyne. 2. Serum concentrations of VTG were also highest in fish from the Tyne stations. 3. Male fish from the Tyne also displayed high levels of testicular abnormalities (up to 53% of fish) compared to the Solway population (no abnormalities recorded) and 4. the HSI of male flounder from the Tyne were significantly greater than for males from the Solway site. This study is the first to demonstrate oestrogenic effects on a wild population of a marine fish exposed to sewage effluent. The high levels of abnormalities recorded raises concerns about the long term health of fish populations in areas receiving large volumes of effluent, these are discussed.

The Role of Recolonization Processes in Benthic Communities, With Special Reference to the Interpretation of Predator-Induced Effects

Abstract Predation and disturbance remove individuals from communities and leave gaps suitable for recolonization. In marine rocky-shore communities, these gaps are primarily colonized by recruiting larvae. Field experiments and simulation studies are used to assess the relative importance of planktonic settlement and adult migration in colonizing gaps in soft-bottom communities. Migration of infaunal adults is rapid, cores being recolonized within 24 h. This adult mobility will influence the results of field caging experiments in these environments, and alter the applicability of patch dynamic models of community organization to these systems.

Domestic waste and TBT pollution in coastal areas of Ambon Island (Eastern Indonesia)

Coastal areas of the island of Ambon (eastern Indonesia), but especially Ambon Bay, were polluted by domestic waste. There was severe beach litter pollution and contamination of inshore waters. High incidences of the isopod ectoparasite Renocila sp. on the coral reef fish Abudefduf saxatilis were probably indirect consequences of pollution stress. Symptoms of imposex, presumably caused by tributyltin compounds leaching from the anti-fouling paints used on boat hulls, were severe in some whelk populations in Ambon Bay but were mild or absent from populations elsewhere on the island. Coastal pollution, and the over-exploitation of natural resources, are global problems but are particularly severe in areas of high population density and those adjacent to semi-enclosed and shallow seas. There are, for example, serious problems along much of the north coast of Java. The island has an enormously dense population accounting for only 6.9% of the land area of Indonesia but supporting 60% of its total population of 176 million people. The most acute problems are in Jakarta Bay which receives pollutants from the city of Jakarta. It suffers from heavy metal and sewage pollution (Sutamihardja, 1988; Thayib & Razak, 1988),

Incorporating ecological functioning into the designation and management of marine protected areas

Marine protected areas are generally designed and managed on the basis of the presence and extent of specific habitat types or the habitats of important species. However, it has become clear that in addition to including these ‘structural’ elements of marine systems, management strategies should incorporate a consideration of the functional aspects of the ecosystems. Biological traits analysis (BTA) has been successfully used to describe ecological functioning in marine benthic systems. BTA uses a number of biological characteristics expressed by the taxa present as indicators of key ecosystem functions. Two expert workshops were used to examine the potential for the application of BTA in the designation and management of MPAs. They concluded that BTA represented the best tool currently available for quantifying ecological functioning and agreed on 10-key ecological functions delivered by marine benthic communities. Twenty-four biological traits were also identified by the workshops as indices of these ten functions. In order to demonstrate the practical utility of the approach, BTA using these traits, was applied to a dataset covering benthos from within and around the proposed Eddystone Special Area of Conservation (SW England). The case study demonstrated that with the type of data normally available from conservation assessment type surveys, and a knowledge of the relevant biological traits, it is possible to use a consideration of ecological functioning to set boundaries for the MPA and to inform the site management objectives. The use of structure and function information to inform the designation process and subsequent management of marine protected areas is discussed.

Using indicator species to assess the state of macrobenthic communities

Environmental impact assessments are often followed by the continuous monitoring needed to determine community change. This long-term monitoring can be time-consuming and expensive. The concept of indicator species attempts to use their presence in a sample or area to characterise a certain degree of community change or pollution effects. This approach has been widely applied to benthic monitoring studies. However, many studies develop their own list of ‘indicators’ in cases without having a prior knowledge of the area or any long-term data. This can result in the production of circular arguments. We carry out a meta-analysis on data sets from 5 of the 20 designated United Kingdom’s sewage sludge dumping grounds and the data set from the classic study of Pearson & Rosenberg (1978). We construct a number of indices to examine this robustness across studies. Having refined our criteria for an ‘indicator taxa’ we examine the spatial and temporal changes in macrobenthic communities occurring at the Tyne sewage sludge dumpsite to examine the utility of this approach. Of the total pool of 123 taxa, 81 taxa responded in one study only. While Spio filicornis (O. F. Muller), Spiophanes bombyx (Claparede), Lagis koreni (Malmgren) and Nephtys cirrosa (Ehlers) showed directly contradictory patterns in different locations. The Spearman’s rank correlation test showed a significant negative relationship between the density of macro-litter per station found at the Tyne dumping ground and the abundance of Abra alba (Wood) (r s = 0.462, n = 6, P = 0.1) and Amphiura filiformis (O. F. Muller)(r s = 0.493, n = 6, P = 0.1). These were the only indicator taxa, which showed a strong relationship to sewage contamination. We therefore conclude that while the concept of indicators may be widely applicable, the actual indicator taxa are not. This demonstrate that the used of indicators must be continually developed providing prior information of the study area.

The response of estuarine fish and benthos to an increasing discharge of sewage effluent

Abstract The Tyne Estuary is one of the most anthropogenically impacted estuaries on the east coast of England. Since 1974, some 200 major sewage discharges to the estuary have been intercepted and redirected to Howdon Sewage Treatment Works for primary treatment. This study examines trends in the benthic fauna and fish populations in the vicinity of the sewage works discharge in relation to an increase in the load of sewage effluent discharged to the estuary at Howdon in the period September 1992 to March 1994. The value of observations of both fish and infauna as a monitoring tool is discussed. These are compared to observations of effluent chemistry and also sediment quality of receiving waters

Environmental monitoring of caged fish farming in macrotidal environments

Abstract Recent years have seen considerable expansion in fish farming using sea cages. These have until recently been located in the sheltered and low current environments of sea lochs and fjords. Significant benthic enrichment is known to occur at these sites, but the effect is highly localized. Fish farm development is now occurring in areas with strong tidal flows. The siting of caged fish farming in macro-tidal environments may reduce the environmental impact of the industry on benthic communities at the farm site. However there exists the potential for accumulation of farm wastes in nearby sedimentary sinks. Additionally the longer residence time of the wastes in the water column has the potential, especially in regions with already high nutrient loadings and/or long flushing times, to lead to stimulation of phytoplankton blooms. Environmental monitoring of such developments therefore needs to consider these addition effects.

The recovery of benthic communities along the County Durham coast after cessation of colliery spoil dumping

Abstract Large amounts of coal tailings and minestone have been dumped off the County Durham coast since at least the beginning of the twentieth century. Three sites which have been subjected to colliery waste dumping were studied to assess the effect of the waste on the marine benthos, and the degree of recovery of the benthic communities after the cessation of dumping. A control site was chosen to the north of the impacted sites and presumed to be unaffected by dumping operations. At each site three replicate grabs were taken for macrofaunal analysis and one for sediment analysis (sand-silt ratio and percentage coal by loss on ignition). The colliery waste appears to have had an effect on the benthic fauna present, indicated by the multidimensional scaling (MDS) configurations, which showed a clear separation between the control and the three sites subjected to dumping. The highest diversity was at Easington (6 months after the cessation of dumping) followed by Blackhall and the control, with the lowest at Horden. This suggests that the level of disturbance is such as to result in an increase in diversity of the affected sites. There were clear signs of recovery from the effects of mine waste dumping at Horden 7 1 2 years after the cessation of dumping, although at Blackhall the community is still perturbed 12 1 2 years after the cessation of dumping. This is probably caused by the prevailing southbound current transporting coal waste down to this site, where it appears to accumulate.

The role of epibenthic predators in structuring the marine invertebrate community of a British coastal salt marsh

Abstract The marine fauna of salt marshes are subjected to predation by birds, tidally feeding flatfish, crabs, prawns and small gobiid fish. The role of these epibenthic predators in structuring the community was investigated using cages to exclude predators. A range of designs of cages and partial cages was employed to control for artefacts due to caging, and sufficient cages were employed so that each cage was only sampled once to prevent the compounding of disturbance due to predation and sampling. Two mesh sizes were employed, a fine mesh excluding epibenthic predators and a coarse mesh allowing access by small crabs, prawns and gobiid fish but excluding birds and larger fish. The exclusion was maintained for 2 years. The presence of any experimental structure had a significant effect on the sedimentary regime within the cage. Epibentic predator exclusion let to an increase in infaunal predator density, but had no significant effect on the infaunal deposit feeders. There was some evidence that predators limit the surface deposit feeding gastropood Hydrobia ulvae during the winter. The gastropod Littorina littorea responded positively to the presence of any caging structure; this may be the result of changes in the availability of food, as the sides of a cage support a diatom flora which this species can exploit. The lack of a response from the infaunal deposit feeders is attributed to their horizontal mobility within the sediment. The possible interactions between epibenthic and infaunal predators are discussed.

Assessing Marine Ecosystem Health: The Long-Term Effects of Fishing on Functional Biodiversity in North Sea Benthos

Assessments based on the taxonomic composition and relative abundance of taxa provide valuable information about the effects of anthropogenic activities on benthic systems. However, international agreements also require active conservation of ecosystem functioning as well as biological assemblages. We must therefore learn more about how ecosystems function and why changes occur within them in order to fully understand the implications of human activities. Biological traits analysis allows systems to be described in terms of the characteristics of member taxa, describing functional diversity whilst retaining information on taxa distributions. This study used biological traits analysis to investigate the long-term effects of fishing on benthic infaunal communities. Infaunal abundance was recorded over three decades at two stations, one within and one outside a fishing ground in the central western North Sea. Each taxon present was categorised for the degree to which it exhibited certain biological traits. The distribution of these traits within a sample produced a picture of functional diversity. Multivariate analyses were used to compare trait composition at the stations over time, thus depicting how community functioning responded to physical disturbance. The assemblages at the two stations were functionally distinct at the onset of the study; with differences in size, feeding type and reproductive method. The functional structure changed over time at the station within the fishing ground as the level of exploitation varied. Large animals, predators, scavengers and those eating invertebrates or carrion dominated years of light effort in the fishing ground but were less represented when effort increased. No such changes occurred at the station outside the fishing ground. Fishing seems to have some effect on benthic functional biodiversity and this effect is most obvious when moving from low to moderate levels. The differences between stations at the start of the timeseries may reflect variations in the physical environment or may result from effects of fishing that predate the timeseries.