Temperature, but not pH, compromises sea urchin fertilization and early development under near-future climate change scenarios

Abstract

Global warming is causing ocean warming and acidification. The distribution of Heliocidaris erythrogramma coincides with the eastern Australia climate change hot spot, where disproportionate warming makes marine biota particularly vulnerable to climate change. In keeping with near-future climate change scenarios, we determined the interactive effects of warming and acidification on fertilization and development of this echinoid. Experimental treatments (20-268C, pH 7.6-8.2) were tested in all combinations for the 'business-as-usual' scenario, with 208C/pH 8.2 being ambient. Percentage of fertilization was high (O89%) across all treatments. There was no difference in percentage of normal development in any pH treatment. In elevated temperature conditions, C48C reduced cleavage by 40 per cent and C68C by a further 20 per cent. Normal gastrulation fell below 4 per cent at C68C. At 268C, development was impaired. As the first study of interactive effects of temperature and pH on sea urchin development, we confirm the thermotolerance and pH resilience of fertilization and embryogenesis within predicted climate change scenarios, with negative effects at upper limits of ocean warming. Our findings place single stressor studies in context and emphasize the need for experiments that address ocean warming and acidification concurrently. Although ocean acidification research has focused on impaired calcification, embryos may not reach the skeletogenic stage in a warm ocean.

Temperature modulates the response of the thermophilous sea urchin Arbacia lixula early life stages to CO2-driven acidification

“…Extreme temperature (27 C) was inhibiting fertilization (<1%). A similar impact was observed in H. erythrogramma (Byrne et al, 2009). As a consequence, A. lixula fertilization might be sufficiently resilient to nearfuture ocean warming and acidification although it should be impaired during extreme warming events.…”

“…Mixed responses from negative to positive were observed in P. lividus (Moulin et al, 2011;Martin et al, 2011) and Heliocidaris erythrogramma. Using similar pH changes and working on the same species (H. erythrogramma), Byrne et al (2009;2010a,b) showed no effect on fertilization while Havenhand et al (2008) showed a negative effect. This may partly reflect difference in experimental design (polyandry vs single malefemale crosses, sperm concentration, stability of pH, use of different sperm:egg ratio, sperm-egg contact time etc.…”

“…These include slower somatic and gonadal growth and reflect a shift in energy budgets linked to additional costs for extracellular pH (pHe) and intracellular pH (pHi) regulations rather than direct impact on calcification (Dupont and Thorndyke, 2013). However, interaction between temperature and ocean acidification was only considered in a limited number of studies (Sheppard Brennand et al, 2010;Byrne et al, 2009Byrne et al, , 2010a2011;Caldwell et al, 2011;Catarino et al, 2012a;Ericson et al, 2012;Foo et al, 2012). From this limited dataset, it appears that interaction between temperature and ocean acidification is complex from temperature being the main driver of change to temperature amplifying or diminishing the negative effects of ocean acidification.…”

Science, biodiversity and Australian management of marine ecosystems

“…Deeper water benthic communities are almost completely unstudied and even benthic communities closer inshore are poorly studied especially with regard to natural pertubations over time (Stephenson et al, 1970;Hutchings and Jacoby, 1994). Far less is known about how increasing water temperatures and ocean acidification are affecting benthic communities although we know that species distributions are changing (Ling et al, 2009) and that changes in ocean acidification are impacting on survival of larvae (Byrne, 2011;Byrne et al, 2009Byrne et al, , 2011Preslawski et al, 2008;Ross et al, 2012). IMCRA 4.0 has provided a useful basis for initial planning to address the biodiversity conservation objectives of Australia's Oceans Policy.…”

CO2-induced fertilization impairment in Strongylocentrotus droebachiensis collected in the Arctic

“…Fertilization experiment procedures were performed according to the literature (USEPA 1993;Havenhand et al 2008;Byrne et al 2009;Bay et al 1993;Lera and Pellegrini 2006). For each fertilization experiment, 4-6 females and 2-4 males were induced to spawn by intracoelomic injection of 1 ml KCl 0.55 M. Females shed the eggs into filtered seawater at 2-3°C.…”