Publications

Adult female perch (Perca fluviatilis) were investigated at several stations in the Stockholm archipelago in a gradient from Stockholm’s central waterways, through the archipelago to the open Baltic Sea. Various large-scale anthropogenic activities in and around the central part of the city have continuously contaminated especially the inner part of the approximately 80 km long gradient during the past 40 years.

The somatic condition factor, average yearly growth and percentage of sexually maturating females were recorded. Other physiological biomarkers, such as the somatic indices of visceral fat weight, spleen weight, liver weight and gonad weight (GSI) were also included in the study. The biochemical variables investigated were whole blood glucose and haemoglobin, as well as DNA adducts (nuclease P1 version of the 32P-postlabeling methodology), enzymatic activities of CYP1A (ethoxyresorufin O-deethylase), glutathione reductase, glutathione-S-transferase, catalase and glucose-6-phosphate dehydrogenase in the liver and acethylcholinesterase in muscle tissue. Finally, P450arom activity was analyzed in brain tissue.

Our results clearly suggest adverse effects on fish from the stations located within 20-30 km from Stockholm. The GSI and the ratios of sexually mature fish were decreased. The response of many of the biochemical biomarkers indicated an increase in pollution levels as the city is approached. Some of the biomarkers, such as EROD activity and DNA adducts showed, however, surprisingly low responses. Our interpretation of these results is that high chronic exposure has caused physiological and/or genetic resistance to normal biomarker response. In fact, supplementary laboratory studies indicate that this indeed could be the case. In one study, fish from the vicinity of Stockholm did not respond to pure benzo(a)pyrene exposure; in another study, control fish exposed to water/sediment from the area showed a greater response than the feral fish.