Ocean acidification an aquaculture issue, not a climate change issue

Ocean acidification will be included in the aquaculture chapter of the Proposed Marlborough Environment Plan rather than the climate change chapter.

Ocean acidification will be included in the aquaculture chapter of the Proposed Marlborough Environment Plan rather than the climate change chapter.

A proposal to have ocean acidification addressed in the climate change chapter of Marlborough’s new environment plan has been knocked back, with it instead being addressed in the plan’s yet-to-be-released aquaculture chapter.

The Marine Farming Association and Aquaculture New Zealand made submissions in the Proposed Marlborough Environment Plan calling for the climate change chapter to be renamed “Climate Change and Ocean Acidification” and for policies to address the two challenges – both caused by increased carbon dioxide in the atmosphere.

The panel acknowledged the “serious potential threat” ocean acidification posed to Marlborough’s marine ecology but declined their submission on the grounds that ocean acidification was “not an effect of climate change”.

It has raised concerns among climate change commentators who believe ocean acidification, a “dangerous situation”, should be receiving more attention.

Climate scientist professor James Renwick said the panel was “technically” correct in their reason not to include acidification in the climate change chapter, but it was “sort of splitting hairs”.

“Because climate change and acidification are both driven by the same thing, I would see them as equally important aspects of the same problem,” Renwick said.

Ocean acidification and climate change were both caused by human emissions of greenhouse gases, he said.

The ocean “soaks up” carbon dioxide, which alters the chemistry of the sea water and results in it becoming more acidic.

It posed a threat to ecosystems and “could be quite damaging to marine life generally”, as some creatures struggled to grow shells in the acidic environment.

“Acidification of the ocean is a really dangerous situation that we should be paying more attention to,” Renwick said.

Choosing to address ocean acidification through the lens of aquaculture was a “bit narrow” as it affected more than just life in marine farms, he said.

“There’s a lot of knock-on effects for acidification generally. It affects fisheries, it affects life in general and that could have huge consequences economically and for our lives.”

Marine Farming Association general manager Ned Wells said the two processes were “inherently linked”.

“The carbon emissions that are responsible for temperature increases are also causing ocean acidification.”

Ocean acidification has two primary impacts on shellfish aquaculture, he said.

Lower pH could affect fecundity and the survival of larvae and spat and secondly, bivalves were reliant on calcium carbonate being readily available in seawater to form their shells.

“Reduced availability causes stress, which can affect growth rates and susceptibility to disease.”

He also noted that the impacts of acidification would not only affect aquaculture species.

“Currently, there is insufficient research to split out the impacts of ocean acidification from other issues such as coastal acidification and increasing water temperatures,” Wells said.

“The industry is however already preparing for change through resilience research and selective breeding.”

A Marlborough District Council spokesman said ocean acidification would be included in the aquaculture chapter which was yet to be released.

Aquaculture New Zealand was approached for comment.

Alice Angeloni, Stuff, 13 March 2020. Article.

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