|
Passive samplers enable it to measure concentrations of compounds in water systems by the exchange between sampler and water until an equilibrium is reached. But the concentration in an organism is not only dependent on the environment, also intake, metabolism, fat content and growth are important. Results from passive samplers can’t be corrected for those influences. Therefore passive samplers can’t be used for the moment without further research as an alternative for eel as biological indicator.
Simulation models can be used to predict the accumulation of compounds in organisms. But a model must previous been provided with data which can influence the concentration of compounds in the organism. To get this data a lot of previous research has to be done. Therefore the use of models can’t be directly applied as an alternative option for eel.
Roach (Rutilus rutilus) and bream (Abramis brama) are both good alternatives to replace eel as a biological indicator. Their presence is considerable in the Dutch fresh water bodies and it is not likely that their stock will decline in the near future, which make them sustainable as alternatives for eel. Their trophic levels are comparable to eel so their intake and accumulation are expected to be similar. Their faults comparing to eel are likely to be limited, but have to be quantified. Influences of spawning of roach and bream can be avoided by sampling below the age of reproduction.
The continuation of the program with roach or bream will provide in information with the same expressiveness and is directly practical feasible. |