Warmer and acidified oceans can lead to ‘hidden’ changes in species behaviour

Warmer and acidified oceans can lead to ‘hidden’ changes in species behaviour

Projected ocean warming and acidification not only impacts
the behaviour of individual species but also the wider marine ecosystems which
are influenced by them, a new study shows.

Research published in Nature
Climate Change
shows that in warmer seawater with lower pH, a common clam –
the peppery furrow shell (Scrobicularia
plana
) – makes considerable changes to its feeding habits.

Instead of relying predominantly on food from within the
water column, it changed its behaviour to use its tube-like feeding siphon to
scrape more of its food from the seafloor.

This in turn led to surface-dwelling invertebrates showing
greater tolerance to warming and acidification, most likely due to the
stimulatory effect of the clam’s altered feeding on their microalgal food
resources.

The study was conducted by researchers at Ghent University
(Belgium), University of Plymouth (UK) and University of South Carolina (USA).

They say it demonstrates that changes in ocean conditions can
significantly alter the interaction network among porewater nutrients, primary
producers, herbivores and burrowing invertebrates.

They also highlight that mechanistic insights into non-lethal
climate change effects are urgently needed to improve the understanding of
ocean warming and acidification in predicted future ocean conditions.

This particular species of clam is one of the most common
large burrowing bivalves along the northeastern Atlantic, Mediterranean and
Baltic sea coastlines, where it is an important prey species for wading birds
and affects other sediment fauna and biogeochemistry.

For the study, researchers used pressure sensors to test how
the combined effects of experimental warming and acidification influence
feeding behaviour, which is largely hidden from direct observation. They also analysed
how the clam’s presence mediated the combined warming and acidification effects
on ecosystem interactions and population resilience among other species.

Dr Carl Van Colen, a researcher at Ghent University, led the
study. He said:

“This work demonstrates
the importance of incorporating understanding about how species interact with
others and their environment to better predict how individual populations will
cope with climate change. The big advancement in this research came when we
started to use pressure sensors to pick up small changes in sediment porewater
hydraulics that we could link to the behaviour of the clams. By using this
technology we were able to shed light into the ‘hidden’ life of organisms
living burrowed in seafloor sediments.”

Mark
Briffa
, Professor of Animal Behaviour at the University of Plymouth
and one of the study’s co-authors, added:

“This shows how
unexpected the effects of human impacts on our environment can be. If the
behaviour of a given species changes as a result of ocean acidification and
warming, what are the implications for other components of that community? Our
study illustrates the importance of investigating the consequences of human
impacts on the environment at multiple levels including how it affects the way animals
behave.”

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