Sub-lethal predatory shell damage does not affect physiology under high CO2 in the intertidal gastropod Tritia reticulata

Abstract

Sub-lethal predatory shell damage does not affect physiology under high CO 2 in the intertidal gastropod Tritia reticulata Ocean acidification (OA) poses a major threat to marine animals, especially marine shelled invertebrates such as molluscs. Although many organisms are capable of compensating for the effects of OA, this can impose physiological costs and impact performance (e.g. through increased metabolism and decreased growth). Sublethal injuries on shells may provoke changes in energy allocation. Under acidified conditions, organisms would spend less energy on reproduction and somatic growth to repair the damage. Therefore, we analysed the physiological responses of the intertidal gastropod Tritia reticulata during shell regeneration under OA conditions. We simulated a sub-lethal predation event (a notch in the outer lip of the shell) and individuals were exposed to control (pH 8.08) and low pH scenarios (pH 7.88 and 7.65). After two months exposure, all individuals showed shell repair, with a full repair rate observed in 75% of individuals. Contrary to expectations, shell repair following sub-lethal damage and OA had no apparent impact on physiological state in terms of energy reserves (as measured by whole-animal Carbon/Nitrogen) or growth potential (as measured by whole-animal RNA:Protein and RNA:DNA ratios). As an intertidal organism, T. reticulata could be resilient to future global environmental change because of compensatory mechanisms that are inherent in intertidal animals, and may represent a robust species with which to study future scenarios of OA in temperate coastal ecosystems. However, unrestricted food availability during experiment could have played a role in the results and therefore food limitation should be considered in future studies regarding shell repair and metabolism under the effects of OA.

Short-term response of flat tree oyster, Isognomon alatus to CO2 acidified seawater in laboratory and field experiments

“…Individuals of Tritia reticulate were exposed to control ambient pH of 8.08 (control) and low pH scenarios (pH 7.65 and 7.88). After two months of exposure, all individuals showed shell repair, with a full repair rate observed in 75% of individuals (Yokoyama et al, 2020). Ocean acidification did not impact the metabolism and enzyme activities in the blue mussel, Mytilus edulis, although the temperature does (Matoo et al, 2020).…”

“…Coasts and their marine biota are exposed to significant environmental heterogeneity due to natural drivers and anthropogenic stressors (Braga et al, 2020;Ramajo et al, 2020). The impact of anthropogenic ocean acidification on marine life is still unclear (Matoo et al, 2020;Yokoyama et al, 2020).…”

“…Some marine fauna showed resilience to acidified water. When the gastropod, Tritia reticulate were cultured in high CO 2 , it resulted in shell damage without physiological stress (Yokoyama et al, 2020). Individuals of Tritia reticulate were exposed to control ambient pH of 8.08 (control) and low pH scenarios (pH 7.65 and 7.88).…”