Vulnerability of the calcifying larval stage of the Antarctic sea urchin Sterechinus neumayeri to near‐future ocean acidification and warming

Abstract

Stenothermal polar benthic marine invertebrates are highly sensitive to environmental perturbations but little is known about potential synergistic effects of concurrent ocean warming and acidification on development of their embryos and larvae. We examined the effects of these stressors on development to the calcifying larval stage in the Antarctic sea urchin Sterechinus neumayeri in embryos reared in present and future (2100+) ocean conditions from fertilization. Embryos were reared in 2 temperature (ambient: -1.0 °C, + 2 °C : 1.0 °C) and 3 pH (ambient: pH 8.0, -0.2-0.4 pH units: 7.8,7.6) levels. Principle coordinates analysis on five larval metrics showed a significant effect of temperature and pH on the pattern of growth. Within each temperature, larvae were separated by pH treatment, a pattern primarily influenced by larval arm and body length. Growth was accelerated by temperature with a 20-28% increase in postoral (PO) length at +2 °C across all pH levels. Growth was strongly depressed by reduced pH with a 8-19% decrease in PO length at pH 7.6-7.8 at both temperatures. The boost in growth caused by warming resulted in larvae that were larger than would be observed if acidification was examined in the absence of warming. However, there was no significant interaction between these stressors. The increase in left-right asymmetry and altered body allometry indicated that decreased pH disrupted developmental patterning and acted as a teratogen (agent causing developmental malformation). Decreased developmental success with just a 2 °C warming indicates that development in S. neumayeri is particularly sensitive to increased temperature. Increased temperature also altered larval allometry. Altered body shape impairs swimming and feeding in echinoplutei. In the absence of adaptation, it appears that the larval phase may be a bottleneck for survivorship of S. neumayeri in a changing ocean in a location where poleward migration to escape inhospitable conditions is not possible.

The stunting effect of a high CO2ocean on calcification and development in sea urchin larvae, a synthesis from the tropics to the poles

“…We analysed data on arm length prior to commencement of feeding because after food is introduced to sea urchin larval cultures, comparisons between studies are confounded by the natural phenotypic plasticity in arm growth due to a feedback mechanism linking nutritive rstb.royalsocietypublishing.org Phil Trans R Soc B 368: 20120439 environment (food levels and larval density) and arm length, the expression of which differs among echinoid families [40,41]. Most studies report pH on the pH NIST (National Institute of Standards and Technology) scale, which is approximately 0.1 units lower than the pH t (total) scale ( [69], see also, [26,58]). To compare all data on the NIST scale, we added 0.1 pH units to the pH t values provided by studies that used this scale.…”

Juvenile Antarctic rockcod,Trematomus bernacchii, are physiologically robust to CO2–acidified seawater

“…Such results suggest that in polar regions the effects of GCC may manifest in greater P CO2 variability. Potential biological effects of elevated P CO2 have already been observed in several laboratory studies on Antarctic calcifying marine organisms, including morphological changes with reduced growth (Yu et al, 2013), developmental malformations (Byrne et al, 2013) and the dissolution of shells (Orr et al, 2005;McClintock et al, 2009;Bednaršek et al, 2012). Physiological alterations in oxygen consumption rates, heat shock proteins and enzymes involved in shell growth have also been observed (Cummings et al, 2011).…”

Expression pattern of heat shock proteins during acute thermal stress in the Antarctic sea urchin, Sterechinus neumayeri

“…These studies have focused on the effect of a single stressor or a combination of temperature and pH on adult sea urchins, during fertilization and early developmental stages [53][54][55][56][57]. S. neumayeri has shown that under long term acclimation, adult stages are lest affected by two combined effect of temperature and reduced seawater pH [56].…”