Laboratory and Field Studies
Gene expression and post-translational modifications resulting in elevation of specific stress proteins (e.g. heat shock proteins-HSPS) have become a powerful tool for generating hypotheses regarding the effects of environmental changes on the biology of marine bivalves. Moreover, the metabolic patterns underline the potential for energy supply and the ability of bivalves to defend against stressful conditions.
Determination of threshold levels of a stressor that induces expression of stress proteins, alone or synergistically with other stressors, in vital organs of bivalves can contribute to predicting more precisely the impact of the environmental changes on the physiological performance of bivalves. In this context, bivalve species are studied under specific laboratory conditions to determine the limits of their tolerance in the presence of several stressors (e.g. temperature, salinity, pathogens).
Depending on hydrology, hydrodynamics and geomorphology of the coastlines, however, bivalve species may experience different magnitudes and duration of environmental stressful conditions including water temperature, pH, dissolved oxygen, heavy metals and salinity which are caused by altered freshwater inputs.
Laboratory experiments do not mimic the reality of current and near-future changes driven by climate change in the field. Thus, researchers are increasingly realizing that single-stressor experiments may not be appropriate in assessing the effects of climate change on marine habitats, and consequently, the potential impacts on farming activities often can not be attributed to a single component of climate change.
The physiological performance of marine bivalves is particularly affected by micro-habitats, while climate change exhibits a spatial and temporal heterogeneity. In this context, experiments and samplings of bivalve species are conducted seasonally from several marine areas along the Greek coastline in order to estimate whether local environmental conditions trigger physiological constraints on bivalve species in their habitats. The latter is significant in identifying locations ("refugia") where the impacts of climate change will be comparatively minimal in the short-term.
Moreover, we examine whether mussels' thermal tolerance is enhanced when exposed in bouts of heat shock for a short time. A phenomenon called "heat hardening", or "acquired thermal resistance", which seems to enable mussels to tolerate sublethal temperatures over long-term via gene expression and metabolic reorganization. In the context of global warming, the ability for "acquired thermal resistance" may prove to be a useful tool for the management and conservation of farmed mussels.
