Kari K. Lehtonen

Accumulation of nodularin-like compounds from the cyanobacterium Nodularia spumigena and changes in acetylcholinesterase activity in the clam Macoma balthica during short-term laboratory exposure.

In this laboratory study the effects of the cyanobacterium Nodularia spumigena (strain AV1) that produces hepatotoxic nodularin (NODLN), non-toxic Nodularia sphaerocarpa (strain UP16f) and purified NODLN on the infaunal clam Macoma balthica from the Baltic Sea were examined. N. sphaerocarpa (2.4 and 12.5 mg dw l(-1)), N. spumigena (4 and 20 mg dw l(-1), intracellular NODLN content ca. 4 and 20 microg l(-1)) and purified NODLN (10 and 50 microg l(-1)) were applied in experimental tanks at 24 h intervals for 96 h. Water samples were taken during the experiment for the measurement of soluble NODLN concentrations. The concentrations of total hepatotoxins in the soft tissues were analysed with enzyme-linked immunosorbent assay (ELISA) and NODLN with high-performance liquid chromatography/diode array detection (HPLC/DAD). Acetylcholinesterase (AChE) activity was measured from the foot tissue samples taken at 0, 24 and 96 h. In the water phase, 60-100% of NODLN in the pure-toxin treatments and all the NODLN in N. spumigena treatments appeared as a yet unidentified form with NODLN-like spectral characteristics. The compound was present in similar quantities also in the non-toxic N. sphaerocarpa treatments. In the toxic N. spumigena treatments the tissue concentration of hepatotoxic NODLN-like compounds (measured with ELISA) increased from the control levels of 0.16 to 16.6 microg g(-1) dw (24 h), reaching 30.3 microg g(-1) dw at 96 h. However, <5% of the toxin detected by ELISA could be shown to be NODLN in HPLC/DAD analysis. Matrix-assisted laser desorption/ionisation-time of flight mass spectrometry (MALDI-TOF/MS) analyses revealed no NODLN-glutathione (GSH) conjugates in the tissues of M. balthica. Combining the responses in the AChE activity recorded after 24 and 96 h exposure, increases by 46% (N. spumigena) and 36% (soluble NODLN) compared with the control activity were observed in the low-level toxic exposures. Oppositely, decreases by 19% (N. spumigena) and 27% (soluble NODLN) of control activity were observed in the high-level exposures. Only the differences between the increased and decreased AChE activities were statistically significant, with individuals exposed to high levels expressing approximately 55% of the activity of those exposed to low concentrations. The results show that M. balthica readily ingests toxic N. spumigena and that accumulation of peptides takes place rapidly, which has potential food chain effects through toxin enrichment. However, it appears that M. balthica is at least partly able to metabolise NODLN. In addition to hepatotoxicity, NODLN seems to induce concentration-dependent neurotoxic effects; this must be taken into consideration when applying AChE activity as a biomarker of specific anthropogenic contamination (e.g. organophosphate and carbamate pesticides).

Biochemical biomarkers in adult female perch (Perca fluviatilis) in a chronically polluted gradient in the Stockholm recipient (Sweden)

A battery of biochemical biomarkers and the SigmaPCB concentration in adult female perch (Perca fluviatilis) verified an aquatic pollution gradient with the city of Stockholm (Sweden) as a point source of anthropogenic substances. The investigation included both an upstream gradient, 46 km westwards through Lake Mälaren, and a downstream gradient, 84 km eastwards through the Stockholm archipelago. Besides the main gradient from Stockholm, there were strong indications of pollution coming from the Baltic Sea. The results indicated a severe pollution situation in central Stockholm, with poor health status of the perch, characterised by increased specific EROD activity in the liver, increased liver EROD somatic index, decreased AChE activity in the muscle, increased amount of DNA adducts in the liver, and a high concentration of biliary 1-pyrenol. In addition, laboratory exposure to common EROD inducers elicited an abnormal response, suggestive of chronic intoxication.

Metabolic effects of short-term starvation on the benthic amphipod Pontoporeia affinis Lindström from the northern Baltic Sea

Changes induced by a short-term (8 days) starvation period on the metabolism (VO2, oxygen uptake rate; VNH4, ammonia excretion rate) of the benthic deposit-feeding amphipod Pontoporeia affinis Lindstrom were studied from a Baltic deep (125 m) open-sea population. The experiments were performed during two different nutritional periods: in March, which represents a period when the benthic environment is deficient of good quality food, and in June, when the vernal phytoplankton bloom has enriched the sediment with fresh algal material. In March, the VNH4-N of P. affinis is already extremely low, and the resulting VO2:VNH4-N ratios (atomic O:N) high (> 240), indicating an almost exclusive utilization of lipids as the energy source of metabolism. The initial VNH4-N is considerably higher in June and the O:N ratio (mean 54) indicates an equal use of protein and lipid. The VO2 is less affected by starvation. The O:N ratio elevates during food deprivation as the animals shift their metabolic balance further towards the use of stored lipid. The results suggest that the ammonia excretion of P. Affinis is an indicator of more-or-less recent feeding history of individuals, and the O:N ratio is a potential index for the condition of these animals as it reflects the nutritional state of the benthic environment; for realistic results, animals should not be kept too long (over 3 days) without food in the laboratory prior to measurements. Results from additional NH4-N excretion experiments, performed on animals collected from geographically different locations, show marked deviations in rates of ammonia release, most likely due to differing environmental conditions.

Seasonal variations in the physiological condition of the benthic amphipods Monoporeia affinis and Pontoporeia femorata in the Gulf of Riga (Baltic Sea)

Seasonal variations in the physiological condition of two benthic deposit-feeding amphipods were studied in two environmentally differing areas in the Gulf of Riga (Baltic Sea) with the purpose of estimating their role in benthic mineralisation. At the shallower (26 m) nearshore station, Monoporeia affinis exhibited low ammonia excretion rate (VNH4+) throughout the year. After intensive accumulation of lipids in spring, the lipid reserves of the individuals became rapidly depleted during autumn. Gravid females in winter-early spring showed exceedingly low lipid and triacylglycerol (TAG) levels compared to studies carried out in open-sea areas. Pontoporeia femorata studied at the deeper (43 m) offshore station exhibited a higher VNH4+ at all times with no significant seasonal variation. Lipid and TAG accumulated continuously until November, reaching higher levels than recorded previously for this species. Experiments showed that the temperature coefficient Q10 determined for VNH4+ is likely to depend on the recent feeding history of the amphipods. Mineralisation of nitrogen and carbon by the amphipod populations at the study sites was estimated to be 1.7-3.0 g C and 11.3-13.5 mmol NH4+ m–2 yr–1. Conclusively, both biotic and abiotic factors affect the condition of the amphipods, while the species also have genuine differences in their metabolic characteristics.

Sediment biotesting in the Baltic Sea : The CONTEST Project

Sediments contaminated by human activities usually contain a mixture of chemicals that produce unforeseen combined toxic effects in organisms. Thus, traditional risk assessments based on the concen ...

Biological effects of environmental pollution in fish and mussels inhabiting Klaipėda-Būtingė area (Baltic Sea)

In June and September 2001 and 2002, acetyl cholinesterase activity, metallothioneins level, bile PAH-metabolites, lysosomal membrane stability, DNA adducts, micronuclei, other nuclear abnormalities, immunological response and histopathological incidences were measured in blue mussel (Mytilus edulis) and flounder (Platichthys flesus) collected along a suspected pollution gradient in the Lithuanian coastal zone (near Nemirseta, Būtingė and Palanga). The biomarkers in flounder from the Klaipėda offshore (reference site) zone were analyzed in December 2001 and 2002. The study results showed the lowest level of genotoxicity and cytotoxicity in organisms inhabiting offshore and Palanga localities in spring 2001. The Palanga zone was originally considered as a coastal reference site, whilst an oil spill occurred in the Būtingė oil terminal in November 2001, causing contamination of this area. After the oil spill the significant increase in genotoxicity and cytotoxicity was detected in mussels and flounder from the Palanga and Būtingė localities. The levels of PAH metabolites, lysosomal membrane instability, as well as neoplastic lesions increased also significantly in flounder after the oil spill. Further elevation of cytogenetic damage caused by the oil spill in mussels was also observed in June 2003. Nevertheless, recovery of flounder was shown by some biomarker responses 10 months after the oil spill.