Impact of temperature increase and acidification on growth and the reproductive potential of the clam Ruditapes philippinarum using DEB

F Maynou,E Galimany,M Ramón,M Solé

doi:10.1016/j.ecss.2020.107099

Abstract

We built a simulation model based on Dynamic Energy Budget theory (DEB) to assess the growth and reproductive potential of the Manila clam Ruditapes philippinarum under different temperature and pH conditions, based on environmental values forecasted for the end of the 21st c. under climate change scenarios. The parameters of the DEB model were calibrated with the results of seasonal growth experiments under two levels of temperature (ambient and plus 2–3 °C) and three levels of pH (8.1 used as control and 7.7 and 7.3 representing acidification). The results showed that R. philippinarum is expected to have moderate growth in length or individual body mass (ultimate length and body weight would be larger than current values by 2–3%) when taking into account only the effect of temperature increase. However, acidification is likely to have a deleterious effect on growth, with a decrease of 2–5% length or body weight under the pH value of 7.7 forecasted for the end of the 21st c, or 10–15% under a more extreme scenario (pH = 7.3). However, the aggregated reproductive potential, integrated along a lifetime of 10 years, is likely to increase by 30% with temperature increase. Decreasing pH would impact negatively on reproductive potential, but in all simulations under warmer conditions, reproductive potential values were higher than current, suggesting that temperature increase would compensate losses due to acidification. The results are discussed in relation to their possible impact on aquaculture and fisheries of this important commercial bivalve.

Highlights

Among the environmental changes forecasted for the world’s climate over the current century, further increases in water temperature and acidification are expected in the ocean, as a result of land-based human activities (IPCC, 2019)
Marine bivalves are vulnerable to these physical stressors because, being benthic ectotherms, their biology and physiology will most likely be affected by seawater temperature increase and acidification, which may impair physiological processes related to shell calcification among others (Matozzo and Marin, 2011; Gosling, 2015; Munari et al, 2018)
Several effects on the well-being of bivalves subjected to increased temperature and lowered pH have been reported in the literature including modifications in growth rates, increased immunological response and pathologies, and altered meta bolic rates related to energy production, oxidative stress and detoxification processes (Range et al, 2014; Matozzo and Marin, 2011; Nardi et al, 2018; Liao et al, 2018; Magalhaes et al, 2018; Costa et al, 2020)

Summary

Introduction

Among the environmental changes forecasted for the world’s climate over the current century, further increases in water temperature and acidification are expected in the ocean, as a result of land-based human activities (IPCC, 2019). It has been shown that filtration, ingestion and oxygen-consumption rates of the clam Ruditapes philippinarum (Adams and Reeve, 1850) increased with temperature (Kyung et al, 2008), while acidification resulted in reduced metabolic rates in the clam Ruditapes decussatus (Range et al, 2014). These metabolic modulations may, in turn, alter the relationship between clams and their environ ment, i.e., increasing or diminishing their filtration and the rate of phytoplankton grazing. Munari et al (2018) tested the effect of exposure to increasing concentrations of the drug diclofenac under reduced pH conditions and found that the damage endured by Mytilus galloprovincialis and R. philippinarum from acidifica tion was compounded in some cases, by the exposure to the pharma ceutical drug

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