The use of (14)C tracer technique to assess the functional response of zooplankton community grazing to toxic impact.
The use of functional endpoints in risk assessment of pollutants for marine pelagic communities is scarce, especially for the function of zooplankton communities. This work presents a rapid, inexpensive and ecologically relevant technique to assess the effect of toxic compounds on the grazing rates of zooplankton communities. The combination of a (14)C-tracer labelling technique with a fast (< 3 h) and representative sub-sampling and handling makes it possible to measure changes in food uptake of freshly collected natural zooplankton communities in a short-term assay. The methodology is described and its validity is determined by a full account of the fate of isotope tracers (up to 15% taken up by zooplankton). Egg production of Acartia tonsa cultures exposed to DCOI yielded EC(50) values of 118+/-33 nM DCOI after three days, where EC(50) values from grazing of natural zooplankton communities was 136+/-29 nM DCOI, indicating that grazing was the more sensitive variable. Finally the method was tested in a mesocosm experiment designed to evaluate the toxicity of the antifouling compound zinc pyrithion (ZPT) with an EC(50) value of 17 nM ZPT (SD=3.3 nM, n=3). The method was found to be reproducible both at the community (CV=8-39%) and individual level (CV=23-53%), and could detect small changes in response to a toxicant in a natural pelagic system. The use of natural communities in combination with the fast and cost-effective procedure makes this technique a powerful tool in risk assessment, where lack of ecological relevance or reproducible results often results in unwanted high uncertainties.
Hjorth
Morten
M
Department of Marine Ecology, National Environmental Research Institute, Frederiksborgvej 399, DK-4000 Roskilde, Denmark. moh@dmu.dk
Haller
Rune
R
Dahllöf
Ingela
I
D000818:Animals; D002250:Carbon Radioisotopes; D033342:Copepoda / Q000187:drug effects* / Q000502:physiology; D044785:Cryptophyta / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004784:Environmental Monitoring / Q000379:methods*; D005247:Feeding Behavior / Q000187:drug effects; D005260:Female; D009942:Organometallic Compounds / Q000633:toxicity*; D010063:Ovum / Q000187:drug effects; D010865:Pilot Projects; D011725:Pyridines / Q000633:toxicity*; D018570:Risk Assessment / Q000379:methods; D013844:Thiazoles / Q000633:toxicity*; D015048:Zooplankton / Q000187:drug effects* / Q000502:physiology
D002250:Carbon Radioisotopes; D009942:Organometallic Compounds; D011725:Pyridines; D013844:Thiazoles; C080469:Kathon 930; C010423:pyrithione zinc