Impaired growth and reproductive capacity in marine rockweeds following prolonged environmental contaminant exposure

Intertidal macroalgae are resilient organisms, withstanding daily fluctuations in temperature, salinity and air exposure. These sessile seaweeds are exposed to anthropogenic pollution as an additional stressor in their natural habitat alongside coastal waterways, which are often adjacent to industrial centers. One such habitat in the New Bedford Harbor in Massachusetts has been recognized by government agencies as a site of National Priority after several decades of polychlorinated biphenyl and metal discharge. Research has focused on the effects of these contaminants among large-scale trophic cascades, with less emphasis on sessile primary productivity. Macroalgal members of the community were the focus of this study and were used to evaluate the presence and effect of environmental contaminants. Contaminants prominent in highly polluted regions of the harbor were elevated in tissue samples. Field surveys evaluating density and biomass were conducted in five areas of varying contamination and indicated a drastic inhibition of colonization with increasing contaminant load. No differences were detected between sites in terms of oocyte production in a single receptacle, but only individuals from less contaminated regions released those oocytes. Potential causes of decreased population size may therefore be reduction in individual biomass and a decreased ability to release eggs.