what is the best method to track trophic transfer of heavy metals in marine food chain?
I suggest to check out relevant papers on this topic:
e.g. Croteau et al. 2005, Limnol. Oceanogr., 50, 1511-1519; Zhang and Wang 2006, Limnol. Oceanogr., 51, 2008-2017; Wang et al. 1999, ES&T, 33, 2905-2909;
Hello,
You can estimate these indices based on any effects of a certain toxicant on fish e.g. effect on survival, reproduction, reproductive hormones, enzymes, histopathology, feeding and foraging behaviour and ... You should compare the results of the exposed fish with that of the control group. Also, you should have a reasonable number of treatments (toxicant concentrations) to obtain rationale responses.
Good luck
Ichecked the EPA, no, it is not the standard. I think it is the simplest. You can check EPA website yourself to find the exact definitions for these terms
Sorry I do not agree. This correspond to toxicity test, not tracking the trophic transfer per se. ratio between metal concentration in prey and predator gave you a rough idea of the transfer (although in the field, other accumulation pathway, - sediment and water - can also play a role) - the best way would rbe to realize experiment in laboratory.
Best regards,
MM
Stable isotopes are a good tool to assess trophic transfer of contaminants. In particular nitrogen stable isotopes, because the isotope ratio of this element experience a shift among trophic levels. Thus, you can relate isotope shift with contaminant concentration and evaluate if the transfer exists and also which is the magnitude.
I agree ...in complement the analyses of metal levels in prey and predator. the stable isotopes will help to identify contribution of preys in the diet. But if PR Jayachandran is looking for pur study on metal transfer through trophic pathway..lab experiment with know levels of metals in the preys is more valuable.
thanks for this inputs Maria.
Best,
MM
but how can I estimate other isotope method. Especially in the case of phytoplankton from field? Its biomass will be very low?
I suggest to check out relevant papers on this topic:
e.g. Croteau et al. 2005, Limnol. Oceanogr., 50, 1511-1519; Zhang and Wang 2006, Limnol. Oceanogr., 51, 2008-2017; Wang et al. 1999, ES&T, 33, 2905-2909;
Right Sebastien for croteau et al(lab study with metal stable isotopes..the other papers (Wang's team) are more dealing with radioisotope which is a very efficient methods (see the paper from our team too. Nevertheless, if it is the measurements in the field with phytoplankton, this will not help (only providing some insights). PR Jayachandran could you be more specific on what you are trying to do (lab, field / organism (species) / which metals). ((Please promote the quality of answer for contributors))
In general the stable isotopes analysis is done in the particulate organic matter (POM) collected in the field from which phytoplankton is part. There are several field studies in this topic which reach accurate conclusions, please see http://www.sciencedirect.com/science/article/pii/S0269749100001536.
Marc, if the metal measurement is done in field samples simultaneously, you know the exact metal concentration in predators and preys and if you face this values with the N isotopes you can know the degree of biomagnification.
Thank you for your answer
I can also recommend this paper (attached), which has some relevant information relating to your question.
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