Abstract
Acidification of the seas, caused by increased dissolution of CO2 into surface water, and global warming challenge the adaptation mechanisms of marine organisms. In boreal coastal environments, temperature and pH vary greatly seasonally, but sometimes also rapidly within hours due to upwelling events. We studied if copepod zooplankton living in a fluctuating environment are tolerant to climate change effects predicted for 2100, i.e., a temperature increase of 3°C and a pH decrease of 0.4. Egg production of the copepod Acartia sp. was followed over five consecutive days at four temperature and pH conditions (17°C/ambient pH; 17°C/low pH; 20°C/ambient pH; 20°C/low pH). Egg production was higher in treatments with warmer temperature but the increase was smaller when copepods were simultaneously exposed to warmer temperature and lowered pH. To reveal if maternal effects are important in terms of adaptation to a changing environment, we conducted an egg transplantation experiment, where the produced eggs were moved to a different environment and egg hatching was monitored for three days. When pH changed between the egg production and hatching conditions, it resulted in lower hatching success, but the effect was diminished over the course of the experiment possibly due to improved maternal provisioning. Warmer egg production temperature induced a positive maternal effect and increased the egg hatching rate. Warmer hatching temperature resulted also in earlier hatching. However, the temperature effects appear to be dependent on the ambient sea temperature. Our preliminary results indicate that maternal effects are an important mechanism in the face of environmental change.
Highlights
Increased atmospheric CO2 concentration is causing global warming
For total nauplii production (g5i = 1NPRi ), the effect of temperature and pH interaction corresponded to the total egg production (Fig. 2)
Copepod egg production increased during the experiment in all treatments (LMM: F1,69 = 7.103, P = 0.010; Fig. 3). pH as a single
Summary
Increased atmospheric CO2 concentration is causing global warming. As CO2 dissolves in surface water, carbonate chemistry changes and the concentration of dissolved inorganic carbon increases, thereby decreasing pH and causing ocean acidification [1]. Coastal organisms are subjected to a large array of environmental stressors during their lifetime. In upwelling regions, both surface water temperature and pH can drop substantially within hours when old deep-water is replaced and forced to the surface. Both surface water temperature and pH can drop substantially within hours when old deep-water is replaced and forced to the surface Species that inhabit such fluctuating environments are likely to be tolerant to ocean acidification [2]. Preceding acidification events or regular pH changes can cause strong selection for evolution of acid tolerance [3]
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