Abstract
We examined the impacts of ocean acidification and copper as co-stressors on the reproduction and population level responses of the benthic copepod Tisbe battagliai across two generations. Naupliar production, growth, and cuticle elemental composition were determined for four pH values: 8.06 (control); 7.95; 7.82; 7.67, with copper addition to concentrations equivalent to those in benthic pore waters. An additive synergistic effect was observed; the decline in naupliar production was greater with added copper at decreasing pH than for decreasing pH alone. Naupliar production modelled for the two generations revealed a negative synergistic impact between ocean acidification and environmentally relevant copper concentrations. Conversely, copper addition enhanced copepod growth, with larger copepods produced at each pH compared to the impact of pH alone. Copepod digests revealed significantly reduced cuticle concentrations of sulphur, phosphorus and calcium under decreasing pH; further, copper uptake increased to toxic levels that lead to reduced naupliar production. These data suggest that ocean acidification will enhance copper bioavailability, resulting in larger, but less fecund individuals that may have an overall detrimental outcome for copepod populations.
Highlights
The geological record reveals several periods of past acidification of the global ocean [1] that coincide with marine mass extinctions [2,3]
While the early life histories of several marine organisms have been found to be vulnerable to ocean acidification [14,15], comparatively few studies have examined the long-term, multigenerational impacts that are important for predicting possible future adaptations [16,17,18]
Differences in toxicity have been related to differences in metal binding sites between bottom waters, sediment pore water, suspended particles and sediments [22,23]; for example, cadmium and copper are most toxic in sediment pore waters [22,23]
Summary
The geological record reveals several periods of past acidification of the global ocean [1] that coincide with marine mass extinctions [2,3]. It is important to recognise that ocean acidification is only one aspect of global change [19] and that synergistic effects involving other variables in combination with pH must be considered. One such example is the existence of elevated levels of xenobiotics. As pH decreases, copper bioavailability increases by the increase in free copper ion concentration [24], and toxic effects may be encountered. Richards et al 2011 [25] predicted an increase in free copper ions of 115% over the 100 years in estuarine environments as a result of declining seawater pH and increasing temperature. Ocean acidification may potentially exacerbate the toxic effects of copper in meiobenthic communities and may prove problematic for the fitness of benthic organisms
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
