Ocean acidification affects fishes reproduction

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Ocean acidification affects fishes reproduction

Ocean acidification is the name given to the decrease in the oceanic pH value, caused by the intake of anthropogenic carbon dioxide from the atmosphere. About a quarter of the CO2 present in the atmosphere ends up in the oceans where it is transformed into carbonic acid (H2CO3).

The increase in CO2 in the atmosphere therefore corresponds to a corresponding increase in that dissolved in sea water. It has been estimated that between 1751 and 1994, the surface pH of ocean waters dropped from 8.25 to 8.14, [2] with a corresponding increase in the concentration of H + ions.

The process of continuous acidification of oceanic waters undoubtedly has an effect on the food chain connected to these waters and in particular can affect the lysocline and the compensation depth of the carbonates, which leads to the dissolution of the calcareous shells of the shells of molluscs and calcareous plankton, made up of calcium carbonate (CaCO3).

Now, the study Ocean acidification boosts reproduction in fish via indirect effects, published on the PLoS biology, unfortunately shows how this problem affects fish life.

Ocean acidification affects fishes reproduction

We can read: "Ocean acidification affects species populations and biodiversity through direct negative effects on physiology and behavior.

The indirect effects of elevated CO2 are less well known and can sometimes be counterintuitive. Reproduction lies at the crux of species population replenishment, but we do not know how ocean acidification affects reproduction in the wild.

Here, we use natural CO2 vents at a temperate rocky reef and show that even though ocean acidification acts as a direct stressor, it can indirectly increase energy budgets of fish to stimulate reproduction at no cost to physiological homeostasis.

Female fish maintained energy levels by compensation: They reduced activity (foraging and aggression) to increase reproduction. In male fish, increased reproductive investment was linked to increased energy intake as mediated by intensified foraging on more abundant prey.

Greater biomass of prey at the vents was linked to greater biomass of algae, as mediated by a fertil isation effect of elevated CO2 on primary production. Additionally, the abundance and aggression of paternal carers were elevated at the CO2 vents, which may further boost reproductive success.

These positive indirect effects of elevated CO2 were only observed for the species of fish that was generalistic and competitively dominant, but not for 3 species of subordinate and more specialized fishes. Hence, species that capitalize on future resource enrichment can accelerate their reproduction and increase their populations, thereby altering species communities in a future ocean. "