Heavy metals and their potential physiological effects to Parasesarma bidens from Hong Kong mangrove

Abstract

The mangroves of Hong Kong are exposed to multiple and intense anthropogenic stressors due to their proximity to highly populated and industrialised areas. A major stressor is that of heavy metal pollution, as mangroves effectively accumulate contaminants in their fine-grained sediments. Current research focuses on the state of metal contamination in sediments, failing to consider the potential bioaccumulation in associated organisms. Crabs are vital to the health and resilience of mangroves by performing key ecological roles (e.g. bioturbation and nutrient cycling through burrowing and feeding behaviour), thus it is of interest to examine the bioaccumulation level in these organisms and to investigate potential physiological effects. The concentration of metals (Al, Cu, Cd, Cr, Fe, Mg, Mn, Zn, Ni, Pb, As) were examined within the muscle tissue of Parasesarma bidens collected from four sites exposed to varying levels of heavy metal pollution around Hong Kong using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). The influence of heavy metal exposure on the metabolic performance of P.bidens was also investigated assessing the populations’ thermal performance with respirometric techniques. We hypothesise that crabs sampled from polluted populations will displayed higher concentrations of metals within their tissues compared to those from relatively pristine sites and found that populations exposed to acute levels of metal pollution displayed suppressed oxygen consumption (μmol min-1 g-1) against an increasing thermal gradient (3°C hour-1 from 22 – 50°C) compared to other populations.