Impact of trampling on sandy beach macrofauna

The effects of varying intensities of human trampling on sandy beach macrofauna were investigated at an exposed beach on the Eastern Cape coast. An experimental approach investigated the survival rates of four macrofaunal species which were subjected to human trampling at different intensities in a holiday-activity simulation. It was found that the clamDonax serra was slightly impacted at all trampling intensities whileDonax sordidus and the isopodEurydice longicomis were affected only at high trampling intensities. Vigorous beach games, such as volleyball, may have a damaging effect onD. serra. In a second experiment, the severe effects of human trampling onD. serra and the benthic mysidGastrosaccus psammodytes were investigated using numbered animals in enclosures. The results indicated that few members of the macrofauna were damaged at low trampling intensities but substantial damage occurred under intense trampling.     

Internal distribution of uranium and associated genotoxic damages in the chronically exposed bivalve Corbicula fluminea

Uranium (U) internal distribution and involved effects in the bivalve Corbicula fluminea have been studied after direct chronic exposure (90 d, 10 μg.L-1). U distribution was assessed at the subcellular level (Metal Rich Granules -MRG-, pellets and cytosol fractions) in two main organs of the bivalve (gills and visceral mass). Micro-localisation was investigated by TEM-EDX analysis in the gills epithelium. DNA damage in gill and hemolymph samples was measured by the Comet assay. The 90-d exposure period led to a significant increase of U concentration in gills over time (×5) and a large U quantity in subcellular granules in gills. Finally, a significant increase (×2) in DNA damage was noted in exposed gills and haemocytes. This study shows that the accumulation levels and consequently the potential toxicity cannot be successfully predicted only on the basis of concentration in water or in tissues and subcellular fractions after chronic exposure.     

Specific biomagnification of polychlorinated dibenzo-p-dioxins and dibenzofurans in tufted ducks (Aythya fuligula), common cormorants (Phalacrocorax carbo) and their prey from Lake Shinji, Japan

Polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDDs/DFs) were detected in waterfowl such as common cormorants, tufted ducks, and their prey, namely fish and bivalves from Lake Shinji, Japan. The concentration of total PCDDs/DFs-TEQ was found to be higher in the muscle tissues of common cormorants than in those of tufted ducks. The results of hierarchical cluster analysis implied that the residue distribution pattern of PCDD/DF homologues was considerably different between these two species. Furthermore, biomagnification factors (BMFs) were estimated from bivalves as prey to tufted duck muscles as target organs. Despite the highest concentrations of 1,3,6,8- and 1,3,7,9-TeCDD in tufted ducks and their prey, however, the BMFs of these isomers were calculated to be lower than those of the toxic 2,3,7,8-substituted PCDDs/DFs. On the other hand, log BMF of toxic 2,3,7,8-substituted PCDDs/DFs were significantly higher for lower chlorinated isomers than those of the higher chlorinated isomers. The biota-sediment accumulation factors (BSAFs) of PCDDs/DFs were also estimated using shijimi clam and fish samples against sediment from Lake Shinji. The average BSAFs were estimated and ranged from 4.0×10⁻³ to 2.2×10⁻¹ and 2.0×10⁻⁴ to 2.0×10⁻¹ for bivalve and fish samples, respectively. Based on calculated BMFs and BSAFs, the total PCDD/DF-TEQ levels in the tufted duck were estimated to have been lowest (2.0 pg TEQ/g dry weight basis) in 1947 and highest (9.8 pg TEQ/g) in 1971.     

Faecal Coliforms in Bivalve Harvesting Areas of the Alvor Lagoon (Southern Portugal): Influence of Seasonal Variability and Urban Development

Faecal coliform (FC) levels in surface water and clams (Ruditapes decussatus) and variations in environmental parameters were studied in two bivalve harvesting areas in the Alvor lagoon (southern Portugal). Land use and cover characteristics in adjacent subwatersheds were also analysed to assess their contributions as sources of faecal contamination. High FC levels in clams from the harvesting area in the most urbanized subwatershed (impervious surface coverage ≈ 10.5%) were positively associated with rainfall and with the cooler periods of the year. FC levels in clams from the least urbanized subwatershed were generally very low and did not present any detectable seasonal trend. From these results, it was concluded that the periodic deterioration of the microbiological quality of clams derives from the cumulative impact of the reservoir of faecal contamination created in urbanized areas, entering into the lagoon during storm water runoff.     

Identification of PAHs Sources in Bivalves and Sediments 5 Years After the Sea Prince Oil Spill in Korea

On 23 July 1995, the oil tanker Sea Prince ran aground near Son Island, off the South Coast of Korea and spilled 5040 tons of crude and fuel oil into the marine environment. The effects of the Sea Prince oil spill on the marine environment have been investigated since 1996. The main objectives of this study were to find out the residual effects of beached oil and transport of dispersed oil into the subtidal area. Twenty-four PARs were analyzed and principal component analysis was performed to elucidate weathering status, bioaccumulation pattern, and input sources. There were signs of bioconcentration of oil-derived PAHs in mussels of stranded oil remained sites. However, environmental factors overwhelmed these so that all the bivalves studied showed similar pattern in the last two sampling campaigns. There was no significant evidence of transport of oil-derived PAHs into the subtidal environment. However, one station showed an exceptionally high concentration (923 ng/g dry weight), which implies the limited input of particle-bound PAHs into this confined area.     

Characterization of ²⁴¹ Am and ¹³⁴Cs bioaccumulation in the king scallop Pecten maximus: investigation via three exposure pathways

In order to understand the bioaccumulation of ²⁴¹Am and ¹³⁴Cs in scallops living in sediments, the uptake and depuration kinetics of these two elements were investigated in the king scallop Pecten maximus exposed via seawater, food, or sediment under laboratory conditions. Generally, ²⁴¹Am accumulation was higher and its retention was stronger than ¹³⁴Cs. This was especially obvious when considering whole animals exposed through seawater with whole-body concentration factors (CF_7d) of 62 vs. 1, absorption efficiencies (A_0l) of 78 vs. 45 for seawater and biological half-lives (T_b½l) of 892 d vs. 22 d for ²⁴¹Am and ¹³⁴Cs, respectively. In contrast, following a single feeding with radiolabelled phytoplankton, the assimilation efficiency (AE) and T_b½l of ¹³⁴Cs were higher than those of ²⁴¹Am (AE: 28% vs. 20%; T_b½l: 14 d vs. 9 d). Among scallop tissues, the shells always contained the higher proportion of the total body burden of ²⁴¹Am whatever the exposure pathway. In contrast, the whole soft parts presented the major fraction of whole-body burden of ¹³⁴Cs, which was generally associated with muscular tissues. Our results showed that the two radionuclides have contrasting behaviors in scallops, in relation to their physico-chemical properties.     

Bioaccumulation and metabolisation of (14)C-pyrene by the Pacific oyster Crassostrea gigas exposed via seawater

The first objective of this study was to determine the bioaccumulation kinetics of pyrene in the soft tissues of Crassostrea gigas (mantle, muscle, gills, digestive gland, and the remaining soft tissues). As bivalves can biotransform hydrocarbons in more polar compounds (metabolites) that are more easily excreted, the second objective was to investigate the oyster capacity to metabolize pyrene into its metabolite, the 1-hydroxypyrene. To these ends, oysters were exposed 24 h to waterborne ¹⁴C-pyrene then placed in depuration conditions for 15 d. Oysters efficiently bioaccumulated pyrene in their soft tissues and equilibrium was reached within the exposure time. The metabolite1-hydroxypyrene was also detected in oyster tissues but represented only 4-14% of the parent pyrene. At the end of the exposure period, the gills and the mantle showed the highest pyrene proportion of total soft tissue content, i.e. 47% and 26%, respectively. After 15 d of depuration, the mantle contained 32% and 30% of the remaining pyrene and 1-hydroxypyrene, respectively. As C. gigas did not display a high capacity for metabolizing pyrene, it can be considered as a good bioindicator species to survey and monitor pyrene contamination in the coastal marine environment.