On plankton production in Kungsbacka Fjord,an estuary on the Swedish west coast

Environmental conditions, primary production, and zooplankton populations were studied from May, 1969 to November, 1970 at one station in Kungsbacka Fjord, Sweden. The fjord, with an arca of 53 km², is a moderately polluted estuary, with a small tidal range. Data for primary production and environmental parameters were correlated using Spearman's rank correlation coefficient. The annual rate of primary production in 1970 was about 100 gC·m^-2. Carbon fixation was about 80 g·m^-2 in May–November in1969 and 1970. The average monthly rate was highest in June, 1970, with 25 gC·m^-2; about 15 gC·m^-2 was recorded in August–October of both years. Carbon fixation by the phytoplankton was estimated to be about 2,800 tons in the whole fjord in 1970. The average fresh-water inflow to the fjord, amounting to about 13 m³·sec^-1, added about 380 tons of organic carbon, 45 tons of nitrogen, and 4.5 tons of phosphorus per month. Primary production displayed strong correlation with temperature at different depths (P<0.05 to 0.001), indicating the sediments to be the most important nutrient source. A total of 19 holoplanktonic zooplankton species was identified, copepods being the dominant group. The highest zooplankton biomass, 800 to 900 mg·m^-3, was recorded in June of both years. The production of copepods in May–October was about 1 gC·m^-2 in both years. The total secondary production of the zooplankton was calculated as only 1.8 gC·m^-2 in 1970.     

The indirect effects of eutrophication on habitat choice and survival of fish larvae in the Baltic Sea

The structure of the habitat is usually crucial for growth and survival of young life stages. Presently, some nursery areas of fish larvae are changing due to eutrophication, e.g. due to enhanced growth of ephemeral filamentous algae at the expense of perennial species. We studied the influence of two habitats, one with filamentous algae (Cladophora glomerata) and the other with bladder wrack (Fucus vesiculosus), on habitat choice of pike larvae (Esox lucius) in the absence/presence of a predator or a competitor. We further tested whether the habitat choice is adaptive in increasing survival under predation threat. In contrast to expectations, pike larvae preferred the habitat with ephemeral filamentous algae to the bladder wrack, thriving in clean waters, independent of the presence/absence of both predator/competitor. In addition, the survival of the larvae was higher in the filamentous algae in the presence of predators, which suggested that the habitat preference of the larvae was adaptive. The structure of the bladderwrack habitat was probably too open for newly hatched larvae, which implies that F. vesiculosus and other large brown algae are not as important refuges for young larvae as previously thought.     

Organochlorine pollutants in Scots pine needles--biological and site related variation within a forest stand

To study the biological variation in the content of some persistent organic pollutants, viz hexachlorobenzene (HCB), alpha- and gamma-hexachlorocyclohexane (alpha- and gamma-HCH), and 1,1,1-trichloro-2,2-bis-(4-chlorophenyl)-ethane (DDT) were analysed in needles from Scots pine trees growing at an isolated peninsula south of Stockholm, Sweden. The concentration variations of each compound was evaluated by a nested analysis of variance (ANOVA) with sampling site specific compass direction, individual tree, and sampling height as factors. Two pair-wise post hoc tests were used to test significant results from the ANOVA. The hexachlorocyclohexanes showed no significant differences between sampling site, trees or sampling height. DDT concentration was significantly lower at the sampling site with the densest vegetation compared to at least three of the other sampling sites. HCB was significantly lower at the lowest sampling height (0.5 m).     

A net loss: policy instruments for commercial cod fishing in Sweden

This paper describes the overfishing of the seas, in particular for cod in Sweden. It discusses policy instruments such as individual quotas, labelling and marine reserves. A tentative conclusion is that something needs to be done to the very structure of the policy instruments used. Information on stock depletion is available but goes unheeded and is counteracted by fishermen who want to fish more and who are routinely supported by "the political establishment" who appear to be most concerned about (short-term) employment. The whole debate is taking place before the eyes of a general public that does not care sufficiently and difficult international bureaucracy. In this situation, the most important changes may be to strengthen both the rights and the duties of the fishermen. The integrity of fish stocks must be given absolute priority, but it is also important to motivate the fishermen with a greater stake and interest in the stock by giving them quotas that have, as far as possible, the characteristics of property.     

Hexachlorobenzene as an indicator of dioxin production from combustion

The production of polychlorinated dioxins and dibenzofurans shows a strong correlation with the production of hexachlorobenzene. Hexachlorobenzene can be used as an indicator for the production of chlorinated aromatics.     

Solubility and Potential Mobility of Heavy Metals in Two Contaminated Urban Soils from Stockholm,Sweden

The solubility and potential mobility of heavy metals (Cd, Cu,Hg, Pb and Zn) in two urban soils were studied by sequential andleaching extractions (rainwater). Compared to rural (arable) soils on similar parent material, the urban soils were highlycontaminated with Hg and Pb and to a lesser extent also with Cd,Cu and Zn. Metal concentrations in rainwater leachates were related to sequential extractions and metal levels reported fromStockholm groundwater. Cadmium and Zn in the soils were mainly recovered in easily extractable fractions, whereas Cu and Pb were complex bound. Concentrations of Pb in the residual fractionwere between two- and eightfold those in arable soils, indicatingthat the sequential extraction scheme did not reflect the solidphases affected by anthropogenic inputs. Cadmium and Zn conc. inthe rainwater leachates were within the range detected in Stockholm groundwater, while Cu and Pb conc. were higher, whichsuggests that Cu and Pb released from the surface soil were immobilised in deeper soil layers. In a soil highly contaminatedwith Hg, the Hg conc. in the leachate was above the median concentration, but still 50 times lower than the max concentration found in groundwater, indicating the possibilityof other sources. In conclusion, it proved difficult to quantitatively predict the mobility of metals in soils by sequential extractions.