H. Parkman et M. Meili, MERCURY IN MACROINVERTEBRATES FROM SWEDISH FOREST LAKES - INFLUENCE OF LAKE TYPE, HABITAT, LIFE-CYCLE, AND FOOD QUALITY, Canadian journal of fisheries and aquatic sciences, 50(3), 1993, pp. 521-534
Mercury concentrations in lacustrine macroinvertebrates were concurren
tly studied in eight remote Swedish forest lakes of differing dystroph
y, acidity, and eutrophy. The aim was to assess the influence of ecolo
gical factors (taxon, habitat, and feeding habits), chemical factors (
characterizing different types of lakes), and regional and climatic fa
ctors (Hg deposition and mean temperature) on the accumulation of Hg.
Concentrations varied from <50 to >5000 ng Hg.g dry weight-1. A large
part of this high variability could be ascribed to differences in wate
r and sediment chemistry, ecological niches, and species-specific seas
onalities. Both taxonomic composition and Hg concentrations were highl
y dependent on the type of lake. Concentrations were highest in acidic
dystrophic lakes and lowest in oligotrophic lakes. Mean Hg concentrat
ions in the examined taxa within a lake differed 100-fold. Contrary to
widely held views on biomagnification, the lowest concentrations amon
g profundal chironomids were found in predators whereas the highest co
ncentrations occurred in detritivores. Seasonal variations were neglig
ible in some taxa but considerable in others and appeared in some taxa
to be related to the life cycle. We conclude that Hg accumulation in
macroinvertebrates is largely determined by feeding behaviour and food
quality.