Corrigendum

Distribution of 118 species of Amphipoda, Mysidacea and Decapoda, sampled in 1984 and 1985 with an epibenthic sledge along a transect from the Skagerrak to the inner Gullmarfjord (Sweden), is described. Amphipods were richest in species in the Skagerrak, while most mysid species were taken at the sill. Decapods did not display any clear pattern. Twinspan, a multivariate data analysis program, divided the samples into four groups: (I) deep-fjord samples; (II) sill, shallow-fjord and deep-basin samples; (III) sill samples; (IV) Skagerrak samples. Characteristic species of the groups were identified with a pseudoF-test. Detrended Correspondence Analysis indicated seasonal faunal changes at 42 and 72 m depths. At both depths a shift in numerical dominance from amphipods to mysids was found in winter. The most pronounced changes seemed to occur at 42 m. Changes in composition and abundance of species during a renewal of the bottom water indicated that mysids were influenced by presumed near-bottom currents, while amphipods and decapods were not. Comparison of the present amphipod fauna with the fauna in 1933–37 revealed significant differences. The fauna in the deep basin was impoverished and the Lilljeborgidae, earlier represented by three species, had disappeared since the 1930s. The changes are most likely caused by eutrophication of the fjord.     

The costs of secondary sexual characters in the lekking great snipe (Gallinago media)

Summary Recent studies of the lekking great snipe (Gallinago media) have shown that male mating success increases with display rate and the amount of white on the tail. An obvious question then arises: what is setting the limits to male display rate and to the evolution of even whiter tails? In this study the costs of these two traits are considered. In the case of the white on the tail, almost no predation was observed during the display period. However, predation on the winter grounds and/or during migration cannot be ruled out. Males differed in the amount of white on the tail between years. It is suggested that increasing the amount of white is costly, though the reason for this is still unknown. In the case of display rate, it is shown that predation cannot be a considerable cost, again because of the near absence of predation on the leks. Instead, it is shown that male displays are energetically costly. The daily energy expenditure of displaying males was estimated to be on average 4 times the basal metabolic rate, which is close to the supposed maximum sustainable work load for birds. Furthermore, males lost on average 1.8 g per h (1.7% of the body mass) which is about 7.2 g (6.8%) during a night of display activity. Males do gain some weight during the day when no displays are performed but loose on average 9 g during an 11-day period in the early part of the breeding season. These results indicate that high energetic demands set the limits to male display performance and that males do not have to trade off the benefit of attracting females by their displays against a cost of attracting predators. Offprint requests to: J. Höglund     

Assessing Secchi and photic zone depth in the Baltic Sea from satellite data

Long-term trends in the Secchi depth of the Baltic Sea have been interpreted in terms of eutrophication. The spectral attenuation coefficient Kd (490) can be estimated from remote sensing data. Given the empirical and theoretical relationships between diffuse attenuation and Secchi depth, it is therefore possible to estimate the trophic state from remote sensing data. This paper considers relationships among remotely sensed and in-water measured K (490), and Secchi depth data obtained during dedicated sea-truthing campaigns in the eastern Baltic Proper in 1999 (4) and in the western Baltic Proper/Himmerfj?rden area during 2001 and 2002. In-water measurements are used to establish the relationship between the PAR and the spectral attenuation coefficient in the Baltic Sea via regression analysis. The analysis showed that in the area of investigation Kd(490) is about 1.48 times higher than Kd (PAR). This relationship is then used to define the link between the photic zone depth and the remote sensing optical depth, Kd (490)-1. The results show that the depth of the euphotic zone is about 6.8 times Kd (490)-1. The regression analysis between Kd (PAR) and Secchi depth confirmed previous work that Kd (PAR) is about 1.7 of the inverse Secchi depth. Furthermore, an in-water algorithm between Secchi depth and Kd (490) is used to simulate a Secchi depth map of the Baltic Sea from SeaWiFS Kd(490) data. This map is verified against sea-truthing data. Kd (490) data derived from satellite is compared to in situ Kd (490), and the sources of error are discussed.     

Hair element concentrations in females in one acid and one alkaline area in southern Sweden

Concentrations of 34 trace elements in hair have been determined in 47 females from an acid region in southern Sweden, who were compared with 43 females from an alkaline area. The concentrations of these elements in hair and drinking water were determined by inductively coupled plasma optical emission spectroscopy and inductively coupled plasma mass spectrometry. The hair concentrations of boron and barium were significantly higher (p < 0.001) in hair samples from the acid region, the hair levels of calcium, strontium, molybdenum, iron, and selenium were significantly higher (p < 0.001) in the alkaline region. For some metals, e.g. calcium, lead, molybdenum, and strontium, there were positive correlations between the concentrations in hair and water (rs = 0.34-0.57; p < or = 0.001), indicating the importance of intake from minerals in water. The increased ratio of selenium/mercury concentrations in hair samples obtained in the alkaline district (p < 0.001) indicates that these subjects may have better protection against the toxic effects of mercury.     

Heavy metal pollution from a point source demonstrated by means of mussels, Mytilusedulis

Heavy metal pollution from a point source has been demonstrated by the levels of mercury in flesh of mussels, $\text{Mytilus}$$\text{edulis}$.     

Biomagnification of organochlorines along a Barents Sea food chain

To trace the biomagnification of organochlorines in marine food chains near Svalbard, which may lead to the high organochlorine concentrations in top predators from the area, we compared concentrations and patterns of organochlorines in selected taxa. The pelagic crustaceans, Calanus spp. (copepods), Thysanoessa spp. (euphausiids), Parathemisto libellula (amphipod), and the fish species, Boreogadus saida (polar cod) and Gadus morhua (cod) were selected to represent the lower trophic levels in the food web. Four seabird species were chosen at the higher trophic levels, Uria lomvia (Brünnich's guillemot), Cepphus grylle (black guillemot), Rissa tridactyla (black-legged kittiwake) and Larus hyperboreus (glaucous gull). We found low concentrations of the organochlorines sigma hexachlorocyclohexanes (sigma HCHs), hexachlorobenzene (HCB), sigma Chlordanes, sigma DDTs and sigma polychlorinated biphenyls (sigma PCBs) in crustaceans (11-50 ng g-1 lipid wt.) and fish (15-222 ng g-1 lipid wt.). In seabirds, the organochlorine concentrations biomagnified one to three orders of magnitude dependent on species and compound class. Glaucous gulls had the highest concentrations of all organochlorines. The organochlorine levels in all taxa except glaucous gull were comparable to those recorded in similar species in the Canadian Arctic. The organochlorine pattern changed from crustaceans and fish to seabirds. Moving up the food chain, the relative contribution of sigma HCHs, HCB and sigma Chlordanes decreased, and the relative contribution of sigma DDTs, sigma PCBs, persistent compounds and metabolites increased. The results reflected trophic transfer of organochlorines along the food chain as well as different elimination potentials due to direct diffusion in crustaceans and fish, and higher contaminant metabolic activity in seabirds.     

Small-scale fisheries,population dynamics,and resource use in Africa: the case of Moree,Ghana

We consider population dynamics and sustainable use and development of fishery resources in Moree, a small-scale fishing and coastal community of 20,000 people in the Central Region of Ghana near Cape Coast. Moree suggests that relationships between population dynamics and fishery resources are more complex than the concept of Malthusian overfishing implies. Reasons include changing biophysical characteristics of the upwelling system along the coast of West Africa; qualitative as well as quantitative changes in fishing activity throughout the year; the market nature of fishing activity and nonlocal demands for fish; regular fishery migration; and institutions regulating fishery resource access at home and at migration destinations. Population and resource relationships in Moree may be the effects of fishery resource and economic changes on migration rather than population pressure on fishery resources. Fisheries management policies must take into account processes that lie beyond the influence of local fishermen.     

Exposure to benzene,toluene, xylenes and total hydrocarbons among snowmobile drivers in Sweden

The exposure to benzene, toluene, xylenes and total hydrocarbons among 25 individuals exposed to exhaust from a snowmobile equipped with a two-stroke engine has been evaluated. Sampling was performed by pumped and diffusive sampling in parallel. There was a relatively bad agreement between the two air-sampling methods. The bad agreement can in part be explained by back diffusion of the substances from the samplers, a high face velocity, and deposition of droplets of unburned gasoline onto or in the vicinity of the samplers.

The levels of benzene ranged from not detectable (0.01 mg m⁻³) to 2.5 mg m⁻³. For toluene, xylenes and total hydrocarbons the exposure was 0.10–12.0, 0.05–13.0 and 0.90–273 mg m⁻³ respectively. The result from two measurements on individuals travelling on an open sleigh at the rear of the vehicle indicated higher levels of benzene, 0.7–0.8 mg m⁻³. Children are often riding as a passenger on a sledge and may thus have a higher exposure than their parents. This study indicates that spare time driving a snowmobile may cause a considerable exposure to benzene. Using a four-stroke engine equipped with a catalyst could reduce the exposure. To reduce the exposure for the passenger on a sleigh an extension of the exhaust pipe may be effective.     

Copepod nutritional condition and pelagic production during autumn in Kosterfjorden,western Sweden

The in situ grazing rate and nutritional condition of copepods were studied during October/November 1985, by analyzing gut fluorescence (feeding), body size and lipid composition (nutritional state), and electron transport system (ETS) activity (respiration rate) of copepods from surface-and deep-water in Kosterfjorden on the Swedish west coast. These parameters were related to the physical and biological environment, as defined by light, hydrography, autotrophic and bacterial production and seston in the water column. The results show a gradual build-up of the autumn phytoplankton bloom in the uppermost meters, with a peak in total autotrophic production in mid October of ca 550 mg C m^–2 d^–1, and a bacterial net production corresponding to 15% of this. Phytoplankton exudates made up, on average, 47% of the primary production and more than 50% of this was utilized by the bacteria. Copepods occurring in the surface-water exhibited grazing rates corresponding to between 11 and 18% of their body C d^–1 and potential growth rates of 0 to 9% d^–1. Copepod populations in the surface water were composed of individuals with higher average body-weight and lower lipid-proportion than those from the deep-water.Calanus finmarchicus in the deep-water showed characters indicating diapause condition, while this was not observed forAcartia clausi. Differences in lipid content and composition indicate thatC. finmarchicus, Pseudocalanus sp. andA. clausi represent three successive points on a scale of tolerance for fluctuations in the food environment. Adult femaleMetridia longa was the only one among seven species/stages of copepods in the deep-water ( 50 m depth) that contained phytoplankton pigments.Study performed through Tjärnö Marine Biological Laboratory, University of Göteborg, S-452 00 Strömstad, Sweden