New measures for shellfish health

New measures for shellfish health

MSc student Aimee Gibson measuring stress enzymes on a microplate reader. (Photo: Michael Ahrens, NIWA)

NIWA’s ecodiagnostics team has some innovative techniques available to measure the health of shellfish communities. Newest are a number of sensitive biomarkers, which enable us to quantify genetic damage and stress-enzyme levels in shellfish accurately and quickly – both hidden indicators of current and future shellfish health.

Measuring sublethal biomarkers provides early warning indicators of declining shellfish health in estuaries, before large-scale population changes take place. It also enables us to compare ‘ecological healthiness’ between estuaries and relate this to different levels of chronic contamination, such as from urban stormwater. By integrating a range of these newer tests with classical population and community measures, we can obtain a comprehensive assessment of shellfish health in different locations. This means more reliable predictions of their long-term fate, and associated ecosystem health, and will help to direct conservation and management action.

For example, a recent comparison of cockles from five Auckland sandflats, all affected by stormwater, found significant differences in genetic damage and levels of stress enzymes between sites. Genetic damage was strongly correlated with sediment zinc concentrations. Our results show that sublethal adverse effects are occurring at sites with seemingly thriving shellfish populations. This provides an early indication of adverse effects due to toxins accumulating in shellfish that, in the long-term, could cause more serious harm to shellfish populations.

The work is funded by the Foundation for Research, Science & Technology.