![]() Allele frequency variation among local populations was marked (mean F(ST) = 0.228) but showed no regional differentiation. We used an hierarchical analysis of allozyme variation to investigate for the freshwater ostracod Candonocypris novaezelandiae the relative contributions of sexual and asexual reproduction to recruitment into 42 local populations and to infer patterns of gene flow within and among four geographical regions (watersheds) in south-eastern Australia. The fossil record can also provide a comparative baseline for evaluating to what extent legislation, intending to cause environmental improvements, has had a positive effect. Consequently, pollution effects on the biota in estuaries can best be evaluated by comparing the natural, pre-pollution assemblages with those of the present day. Differential adaptations to the complex hydrographical and physical conditions that characterize estuarine environmentals often make it difficult to separate natural faunal properties from pollution effects, especially in a temporal context. Most investigations have been carried out in temperate regions, in areas exposed to several pollution sources. Cu-contaminated sediments alone do not seem to promote development of deformed hard-shelled foraminiferal tests beyond the normal range.īenthic foraminiferal distributions in polluted marine areas have been investigated over the last three to four decades, and several workers have pointed out that they provide one of the most sensitive and inexpensive markers available for indicating deterioration of marginal marine environments. fusiformis developed an increasingly patchy distribution pattern. One prom- inent effect of the Cu-contamination is that, at concen- trations higher than about 900 ppm, the opportunistic and dominant S. 2000 ppm had a severe negative impact on the foraminiferal species ability to colonize. This indicates that not even sedi- ment (Cu). There was no significant decrease in the number of species with increasing sedi- ment Cu-enrichment. At the species level, a significant negative effect of the Cu-enrichment could be observed only for Stainforthia fusiformis and Bolivinellina pseudopunctata. The changes, which are revealed through mul- tivariate statistical analyses (MDS-ordination and AN- OSIM tests) of the different treatment assemblages, are reflected by increased equitability and reduced abun- dances in treatments with high (967-977 ppm) and very high (1761-2424 ppm) Cu-concentrations. 900 ppm cause a change in the living (stained) foraminiferal community structure as compared to control values of 70 ppm. The complete depuration occurred at 26 days.Ĭolonization experiments, carried out over a 32-week period at 63 m water depth in the Oslofjord, Norway, have shown that sediment Cu-concentrations of. The bivalve remained contaminated with small concentrations of hydrocarbons for 20 days. After 48 hours in clean river water, tissues burden decreased to 0.22 ppm of hydrocarbons. At the end of the exposure period, the bivalve contains approximately 7.4 ppm. After 25 hours of exposure, the hydrocarbons concentration decreased in the bivalve tissues. After 20 hours, hydrocarbons are present in water at a concentration of 0.09ppm, while the bivalve tissues contained 17.7 ppm hydrocarbons. After 2 hours of exposure, the concentration of hydrocarbons is approximately 0.38 ppm in water, while in tissues it is 4.8 ppm. Hydrocarbons accumulated by the bivalve are slowly during the first few hours of exposure. Hydrocarbons concentrations in the exposure water decreased are slowly in a linear fashion so that no measurable concentrations remained after 32 hours. The bivalve is usually active during the 12– 16 hours of the experiments. The experiments show that there are no mortalities due to WSF of Nahran–Umar crude oil. After the exposure period is over, the bivalve transferred to clean river water for depuration period of 48 hours. The exposure water and animals are periodically taken for analysis of total hydrocarbons concentrations by spectroflurometer. fluminea is exposed to 5ml of WSF of Nahran–Umar crude oil for each liter of river water for 48 hours in the static toxicity test system. This study includes laboratory uptake and depuration experiments. ![]()
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