Radionuclides and the birds at Ravenglass

Since 1983, concern has been expressed about the apparent decline in numbers of birds in the Ravenglass estuary in west Cumbria, particularly of the black-headed gull colony on the Drigg dunes, and suggestions have been made that this decline might be due to excessive radiation in the birds' food and their general environment. Twelve species of marine invertebrates from Ravenglass, most of them known to be important foods for birds, were analysed, and further samples were taken from sites along the west Cumbrian coast. None of these samples showed excessive contamination with any of the radionuclides analysed. Analysis of a sample of bird carcasses from the areas showed oystercatchers (Haematopus ostralegus) and shelduck (Tadorna tadorna) to have some of the highest concentrations of (137)Cs in their tissues; yet their breeding success and populations were not affected. Black-headed gulls, on the other hand, were found to be feeding mainly inland, and were the least contaminated with radionuclides of all the birds at Ravenglass, yet this species and its breeding success were in decline. Calculations of the total dose equivalent rate to the whole body of the most contaminated black-headed gull amounted to 9.8 x 10(-4) mSvh(-1) (approximately equal to 8.4 x 10(-4) mGy h(-1), whole body absorbed dose rate), and the background exposure dose was of the order of 8.3 x 10(-4) mGy h(-1). As a minimum chronic dose of 1000 mGy day(-1) has been found necessary to retard growth of nestling birds, and 9600 mGy over 20 days of incubation to cause the death of 50% of embryos in black-headed gulls' eggs, the concentrations of radionuclides in the foods, body tissues and general environment were at least three orders of magnitude too low to have had any effect. The more likely cause of the desertion of the gullery was the combination of an uncontrolled fox population, the severest outbreak of myxomatosis amongst the rabbits since 1954 and the driest May-July period on record, all in the same year (1984).     

Stakeholder engagement and knowledge exchange in environmental research

It is commonly put forward that effective uptake of research in policy or practice must be built upon a foundation of active knowledge exchange and stakeholder engagement during the research. However, what is often lacking is a systematic appreciation of the specific practices of knowledge exchange and their relative merits. The paper reports on a 2009 survey of 21 research projects within the UK Research Councils' Rural Economy and Land Use Programme regarding the involvement and perceived impact of over a thousand stakeholders in the research. The survey reveals that most stakeholders were involved as research subjects or as event participants. Large numbers were also engaged in the research process itself, including involvement in shaping the direction of research. Stakeholder engagement is perceived as bringing significant benefits to the process of knowledge production. A close relationship is found between mechanisms and approaches to knowledge exchange and the spread of benefits for researchers and stakeholders. Mutual benefits are gained from exchange of staff or where stakeholders are members of research advisory groups. Different stakeholder sectors are also associated with different patterns of engagement, which lead to contrasting impact patterns. Any efforts to alter knowledge exchange processes and outcomes must overcome these differing engagement tendencies. Overall, much greater attention should be given to early processes of knowledge exchange and stakeholder engagement within the lifetime of research projects.     

Evaluating microbial purification during soil treatment of wastewater with multicomponent tracer and surrogate tests

Soil treatment of wastewater has the potential to achieve high purification efficiency, yet the understanding and predictability of purification with respect to removal of viruses and other pathogens is limited. Research has been completed to quantify the removal of virus and bacteria through the use of microbial surrogates and conservative tracers during controlled experiments with three-dimensional pilot-scale soil treatment systems in the laboratory and during the testing of full-scale systems under field conditions. The surrogates and tracers employed included two viruses (MS-2 and PRD-1 bacteriophages), one bacterium (ice-nucleating active Pseudomonas), and one conservative tracer (bromide ion). Efforts have also been made to determine the relationship between viruses and fecal coliform bacteria in soil samples below the wastewater infiltrative surface, and the correlation between Escherichia coli concentrations measured in percolating soil solution as compared with those estimated from analyses of soil solids. The results suggest episodic breakthrough of virus and bacteria during soil treatment of wastewater and a 2 to 3 log (99-99.9%) removal of virus and near complete removal of fecal coliform bacteria during unsaturated flow through 60 to 90 cm of sandy medium. Results also suggest that the fate of fecal coliform bacteria may be indicative of that of viruses in soil media near the infiltrative surface receiving wastewater effluent. Concentrations of fecal coliform in percolating soil solution may be conservatively estimated from analysis of extracted soil solids.     

Interaction of ocean acidification and temperature; the high cost of survival in the brittlestar Ophiura ophiura

This study has demonstrated an interaction between the effect of increased ocean acidity and temperature (40 days exposure) on a number of key physiological parameters in the ophiuroid brittlestar, Ophiura ophiura. Metabolic upregulation is seen in the low pH treatments when combined with low temperature. However, this is far outweighed by the response to elevated temperature (+4.5°C). In the high temperature/low pH treatments treatments (where calcite is undersaturated) there appears to be an energetic trade-off likely in order to maintain net calcification where dissolution of calcium carbonate may occur. This energy deficit results in a ~30% reduction in the rate of arm regeneration at pH 7.3 which is predicted to be reached by the year 2300. This understanding of how O. ophiura responds to ocean acidification, taking into account an interactive effect of temperature, suggests that fitness and survival may indirectly be reduced through slower recovery from arm damage.     

Effects of the polychlorinated biphenyl Aroclor® 1254 on the American oyster Crassostrea virginica

Young oysters (Crassostrea virginica) were continuously exposed to Aroclor^® 1254, a polychlorinated biphenyl (PCB), in flowing, unfiltered seawater. Growth rate (height and in-water weight) was significantly reduced (=0.05) in oysters exposed to 5 g/l (ppb) for 24 weeks. Growth rate was not affected in oysters exposed to 1 ppb for 30 weeks. Mortality was not significant in exposed and control groups. In oysters exposed to 5 ppb, greatest PCB residue (whole body) was 425 mg/kg (ppm), 85,000x the concentration in the water, and less than 0.3 ppm was retained after 28 weeks depuration in PCB-free water. In oysters exposed to 1 ppb, greatest residue was 101 ppm, 101,000x the concentration in the water, and less than 0.2 ppm was retained after 12 weeks depuration. Examination of oysters exposed to 5 ppb of this PCB for pathogenesis revealed atrophy of digestive diverticular epithelium and degeneration of vesicular connective tissues concomitant with leukocytic infiltration, but tissue recovery seemed excellent after 12 weeks depuration.Registered trademark, Monsanto Company, St. Louis, Missouri, USA. Mention of commercial products or trade names does not constitute endorsement by the Environmental Protection Agency.Contribution No. 146, Gulf Breeze Laboratory.     

Lysosomal responses to experimentally injected anthracene in the digestive cells of Mytilus edulis

Experimentally injected anthracene (10 to 100 g mussel^-1) has been shown to induce dose-dependent lysosomal destabilisation and release of hexosaminidase in the digestive cells of Mytilus edulis after 24 h. This destabilisation was accompanied by cytological evidence of cytolysis of the digestive cells. The destabilising effect of 100 g of injected anthracene persisted for 96 h with a return to the control condition by 168 h. These results are discussed in the context of environmental contamination by polycyclic aromatic hydrocarbons.     

Ecological half-life of caesium in roe deer (Capreolus capreolus)

Biological half-lives for various radionuclides have been determined for many animals kept in the laboratory or under controlled conditions. Only occasionally has been it possible to determine the ecological half-lives of radionuclides in wild animals, where the contamination has occurred in their natural habitats. Following the fallout from the Chernobyl accident and its subsequent ingestion by wildlife, no one knew how long it would take the wild animals to eliminate the radionuclides, and in particular radiocaesium, from their bodies. In this study of roe deer (Capreolus capreolus), bucks (males)were shot at weekly/fortnightly intervals from mid-May till the end of July, as part of the annual cull on an area, which included some young forestry (Stone Chest-National Grid Reference NY48090), planted in 1971/72. The ration of 137Cs:134Cs, typical of the Chernobyl fallout, was seldom observed in these animals due to the highly variable concentrations of 137Cs originating from bomb fallout. Therefore, 134Cs was used instead because its presence was almost entirely due to the Chernobyl fallout. After using log10 transformation of the 134Cs concentrations, a significant (p < 0.01) regression was obtained which accounted for 85% of the variation. From the regression, the ecological half-life for 134Cs was found to be 28.3 days.     

Movements of tiger sharks (Galeocerdo cuvier) in coastal Hawaiian waters

The giant clam Tridacna crocea harbors in the mantle tissue symbiotic microalgae commonly called zooxanthellae. Isolated zooxanthellae release glycerol into the medium in the presence of mantle tissue homogenate (MH), but it is not clear whether the cells do so in situ. In order to determine the photosynthetic products released by zooxanthellae in the mantle of the giant clam we traced photosynthetic fixation products from ¹³C- and ¹⁴C-bicarbonate both in the clam and in isolated zooxanthellae (IZ) in the presence or absence of MH. After 15 min incubation in the absence of MH the IZ released less than 0.6% of the fixed labeled carbon, mainly as glucose. The major intracellular photosynthates were neutral lipids, which constituted 20 to 40% of the total extractable ¹⁴C. In the presence of MH, the IZ released up to 5.6% of the total fixed ¹⁴C, mostly as glycerol, and the major intracellular photosynthate was glucose. In an intact clam incubated in sea water containing ¹⁴C-bicarbonate, 46 to 80% of the fixed ¹⁴C was translocated from the zooxanthellae to the host tissues. Most of the ¹⁴C in the hemolymph, in the isolated zooxanthellae and in intact mantle tissue (containing zooxanthellae) was recovered as glucose. No ¹⁴C-glycerol was detected in the mantle after 1 to 30 min incubation, and, even after 60 min, far less ¹⁴C-glycerol was synthesized than by IZ in the presence of MH. The possibility that in clam tissue glycerol is converted to glucose was examined by tracing the labeled carbon from ¹⁴C-glycerol injected into the adductor muscle. After 5 min incubation, no labeled glucose was found in the hemolymph, but after 60 min, some 20% was found as glucose. Thin slices containing zooxanthellae, cut from the surface of the mantle, fixed inorganic carbon supplied as NaH¹⁴CO₃ in the medium and mainly released ¹⁴C-glucose. The addition of MH to the surrounding medium did not affect the release rate or form of release product. When the slices were cut into smaller pieces, however, the ratio of glycerol to glucose in the release product increased. These results indicate that in the presence of MH the metabolism of isolated zooxan- thellae was different from that of zooxanthellae in the mantle. In the presence of MH, isolated zooxanthellae release mostly glycerol, whereas in the mantle they release glucose. Received: 18 February 1998 / Accepted: 4 December 1998