Ocean Acidification Effects on Marine Copepod Dynamics

Ocean acidification, driven by the uptake of anthropogenic carbon dioxide, alters seawater chemistry and lowers pH, with cascading consequences for marine food webs. Copepods, as dominant mesozooplankton, play a pivotal role in carbon cycling and trophic transfer between primary producers and fish. Acidified conditions can impair copepod physiology, affecting survival, development, reproduction and biochemical composition. Direct exposures to lowered pH may disrupt ion regulation and metabolic pathways, while indirect effects through altered phytoplankton food quality can diminish essential fatty acids and lower trophic transfer efficiency. Life-stage sensitivity varies, with early naupliar stages generally more vulnerable than adults, and transgenerational plasticity or adaptive gene expression changes may confer partial resilience. At the ecosystem scale, combined stressors—such as warming, deoxygenation and food limitation—interact synergistically or antagonistically, influencing copepod abundance, body size and reproductive output. Global biogeochemical models and field surveys reveal regional hotspots where multiple stressors overlap, signalling areas of heightened copepod vulnerability. These dynamics have profound implications for fisheries productivity, carbon sequestration and the stability of marine ecosystems under future climate scenarios.

Research from Nature Portfolio

Metabolomic profiling under end-of-century warming and acidification scenarios has revealed that food deprivation imposes a greater physiological stress on Calanus spp. than pH or temperature shifts alone. Key metabolites associated with protein and lipid metabolism, including essential polyunsaturated fatty acids, were significantly altered in starved copepods. This work emphasises the need to contextualise acidification experiments against natural stressors such as variable food availability and highlights the potential for climate-driven changes in microplankton composition to modulate copepod survival and energetics.

Ocean Acidification Effects on Marine Copepod Dynamics publication trend

The graph below shows the total number of articles in ocean acidification effects on marine copepod dynamics across all publications each year (not limited to Nature Index journals).

Technical terms

Ocean acidification: The process by which seawater pH decreases due to absorption of atmospheric CO₂, altering carbonate chemistry.

Copepod: A small planktonic crustacean forming a crucial link between primary producers and higher trophic levels in marine ecosystems.

Metabolomics: The comprehensive analysis of low molecular weight metabolites to assess physiological responses to environmental change.

Mesocosm: A controlled experimental enclosure that simulates natural conditions for studying ecological processes under manipulated variables.

Trophic transfer efficiency: The proportion of energy or biomass transferred from one trophic level to the next, often influenced by prey quality.

References

1. A global biogeography analysis reveals vulnerability of surface marine zooplankton to anthropogenic stressors. One Earth (2024).
2. Combined Effects of Ocean Warming and Acidification on Copepod Abundance, Body Size and Fatty Acid Content. PLOS ONE (2016).
3. Ocean Acidification Affects the Phyto-Zoo Plankton Trophic Transfer Efficiency. PLOS ONE (2016).
4. Regulation of gene expression is associated with tolerance of the Arctic copepod Calanus glacialis to CO2‐acidified sea water. Ecology and Evolution (2017).
5. The metabolic response of marine copepods to environmental warming and ocean acidification in the absence of food. Scientific Reports (2015).
6. Maternal Effects May Act as an Adaptation Mechanism for Copepods Facing pH and Temperature Changes. PLOS ONE (2012).