Effects of medetomidine, a novel antifouling agent, on the burrowing bivalve Abra nitida (Müller)

The effects of medetomidine, a novel antifouling candidate, on the burrowing bivalve Abra nitida were studied. The burrowing behaviour, sediment reworking activity and faeces production were assessed after 24 h exposure of A. nitida to sublethal concentrations of medetomidine. Medetomidine caused a significant decrease in the burrowing response and in the sediment reworking activity. The median effective concentrations (EC50) were 430 nM (86 microg/l) and 4.4 nM (0.9 microg/l), respectively. No effects on the faeces production were detected. Although significant effects of medetomidine on A. nitida were registered, a reversibility of the effects was observed when 24 h-exposed animals were incubated in clean seawater and sediment for 24 h. Considerations relating to the future commercialisation of medetomidine for antifouling purposes are discussed.     

The two reindeer parasites,Hypoderma tarandi andCephenemyia trompe (Oestridae), have evolved similar olfactory receptor abilities to volatiles from their common host

Summary Using the linked gas chromatographical/electroantennogram (GC/EAG) technique it was revealed that the reindeer warble fly (H. tarandi) was specifically able to sense the same components from reindeer interdigital pheromone gland as the reindeer nose bot fly (C. trompe) another reindeer endoparasite. These two species belong to the same family (Oestridae), but different subfamilies, and the evolution towards an endoparasitic life cycle is thought to have been independent. The development of olfactory abilities to find reindeer from long distances is hypothesized to have taken place through convergent evolution or exists because of their common ancestry.     

Bioaccumulation of 4-nonylphenol in marine animals--a re-evaluation

The bioaccumulation of 4-nonylphenol (NP) has been studied in shrimps (Crangon grangon L.), mussels (Mytilus edulis L.) and sticklebacks (Gasterosteus aculeatus L.) exposed to (14)C-NP in running seawater. NP was extracted with high recovery from tissues which were pretreated with pancreatic enzymes. The bioconcentration factor determined of NP in fish was 1300 and in mussels, 3400. These values are 5 and 340 times higher, respectively, than values reported earlier.     

Identification of Characteristic Regions and Representative Stations: A Study of Water Quality Variables in the Kattegat

Gradients in nutrient distributions and the effects of eutrophication are common features in most coastal marine areas. These structures occur in aquatic systems due to spatial differences in hydrography, nutrient loading and key biogeochemical processes. Two statistical methods, cluster analysis and probability mapping, have been used in the present study to determine characteristics and patterns in water quality variables. Combined, these two methods provide a useful tool to statistically determine spatial homogeneity and representativity of areas and stations. A case study is presented here in which water quality variables (salinity, dissolved inorganic nitrogen, dissolved inorganic phosphorus and chlorophyll) in surface waters of the Kattegat are analysed for the time period 1993-1997. It was found that morphology, the proximity to sources of nutrient loading from land, nutrient uptake and the infrequent water exchange between the Baltic Sea in the south and the Skagerrak in the north all contribute to create distinct regions of water quality. Regions with concentrations significantly different from the overall mean are identified. In addition to identification of regions with similar characteristics, representative stations (as well as not representative stations) for the respective regions were made. This type of information can be used to design new or revise old monitoring programs.     

Beat frequency of cilia in the branchial basket of the ascidian Ciona intestinalis in relation to temperature and algal cell concentration

To elucidate the effects of temperature and algal cell concentration on pumping of water in the ascidian Ciona intestinalis a number of different experiments were performed. Beat frequency of the lateral cilia in the openings of the branchial sac was measured in intact specimens using a microprojection objective and a monochrome CCD video camera. At constant low algal cell concentration, beat frequencies increased linearly with temperature from 4.0 Hz (±0.5) at 7.4 °C to 13.6 Hz (±1.6) at 20.1 °C. At a constant temperature of 15 °C, beat frequency decreased with increasing algal cell concentration from approximately 3000 to >10 000 Rhodomonas sp. cells ml⁻¹. The decrease was observed both in experiments where the ascidians had been acclimated to a fixed algal cell concentration and in experiments with changing concentrations. Effect of algal cell concentration on squirting/siphon closure and flow velocity in the exhalent siphon was measured using a thermistor. At low algal cell concentrations, flow velocity in the exhalent siphon was stable, apart from a few short squirts. At very high algal cell concentrations, the flow velocity was reduced and much less stable, with prolonged squirting. The effect of gut content on filtration was studied in experiments with specimens acclimated to high algal cell concentrations. Results showed a close relation between gut clearance and filtration rate. From the experimental results and a qualitative analysis of the Ciona-pump it was concluded that the ciliary beat frequency is proportional to the water flow through the sea squirt and that changes in pumping caused by temperature or algal cell concentration are under nervous control or governed by enzyme kinetics, rather than being a result of physico-mechanical properties, i.e. pump efficiency versus flow resistance, of the ascidian pump. Received: 6 October 1997 / Accepted: 8 October 1998     

Synthesis of [14C]biphenyl and of some chlorinated [14C]biphenyls containing 4-chloro-, 2,4-dichloro- and 2,3,6-trichlorophenyl nuclei from the corresponding labelled anilines

The preparation of ¹⁴C-labelled biphenyl, 2,5-dichlorobiphenyl, 2,4′,5-trichlorobiphenyl, 2,2′,4,5′-tetrachlorobiphenyl, 2′,3,4,4′,5-pentachlorobiphenyl, 2,2′,3,4,4′-pentachlorobiphenyl, 2,3,3′,4′,6-pentachlorobiphenyl and 2,2′,3,3′,6-pentachlorobiphenyl is described [¹⁴C]Aniline hydrogen sulfate used as a starting material was acetylated, chlorinated and deacetylated followed by coupling to benzene or an appropriate chlorobenzene to give the biphenyls labelled in the phenyl nuclei having chlorine atoms at the 4-, 2,4- or 2,3,6-positions, respectively. The structures of the labelled compounds were established by comparison with authentic samples among which 2′,3,4,4′,5- and 2,2′,3,4,4′-pentachlorobiphenyl were not earlier described.A simple method for the preparation of 2,3,6-trichloroacetanilide, unlabelled and labelled, was worked out. 2,6-Dichloroacetanilide in concentrated hydrochloric acid gave the $\text{meta}$ substituted product when treated with chlorine.An improved thin layer chromatographic technique utilizing plates impregnated with certain tetraalkylammonium salts was used for separation of some of the labelled compounds prepared.     

Butyltin compounds in sediment and molluscs from the shipping strait between Denmark and Sweden

The distribution of tributyltin (TBT) contamination in the subtidal zone of the waters between Denmark and Sweden was investigated in relation to major international shipping lanes. Sediment and different benthic molluscs were sampled in transects along and perpendicularly to the shipping lanes in the Sound (?resund) and the Kattegat/Skagerrak region. The samples were analysed for TBT and its degradation products, dibutyltin (DBT) and monobutyltin (MBT), using GC-PFPD. In sediments, the TBT concentration ranged from <1 to 19 ng g(-1) dry weight (dw) with a strong correlation between the TBT concentration and the organic fraction in sediment (r(2)=0.90) in the samples collected in the Sound, where the highest concentrations were found. This relationship was not observed in the samples from the Kattegat because the TBT concentration in most sediment samples was below the limit of detection. In the molluscs, TBT and its degradation products were detected in all samples from the entire area with concentrations ranging from 8.1 ng g(-1) dw in Buccinum undatum to 1316 ng g(-1) dw in Nuculana pernula. The deposit-feeding bivalve N. pernula was found to have a particularly high accumulation potential for TBT. In addition, a strong correlation between TBT concentrations in sediment and N. pernula was found. Therefore this species seems to be an ideal organism for monitoring sediment contamination. The TBT concentration in N. pernula was found to decrease gradually along the shipping lanes from the Sound, through the Kattegat and into the Skagerrak.     

Sedimentation and sulfate reduction under a mussel culture

The sedimentation and dissimilatory sulfate reduction under a blue-mussel culture were quantified in order to gain information on the environmental impact of intense mussel farming. The sedimentation rate (3 g C·m^-2·d^-1) under a culture is nearly three times higher than at a nearby reference station. A build-up of sediment rich in organic material and sulfide takes place under the mussels. At 15°C the sulfate reduction rate was 30.5 mmol SO ₌ ⁴ ·m^-2·^-1 in the upper 10 cm of the mussel sediment. The increase in sedimentation under a mussel culture and the consequent effects should be considered when establishing mussel farms.