[OANNES Foro] Warmer temperatures reduce the predation of an starfish over a sea urchin in the kelp forests of the North-eastern Pacific

Mario Cabrejos casal en infotex.com.pe
Mar Ene 17 07:14:02 PST 2017


Journal of Animal Ecology

·         Accepted manuscript online: 11 January 2017 

·         DOI: 10.1111/1365-2656.12634 


 


Warmer temperatures reduce the influence of an important keystone predator


·         Chiara Bonaviri, Michael Graham, Paola Gianguzza, Nick T. Shears


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Summary


Predator-prey interactions may be strongly influenced by temperature
variations in marine ecosystems. Consequently, climate change may alter the
importance of predators with repercussions for ecosystem functioning and
structure.

In North-eastern Pacific kelp forests, the starfish Pycnopodia helianthoides
is known to be an important predator of the purple sea urchin
Strongylocentrotus purpuratus. Here we investigated the influence of water
temperature on this predator-prey interaction by: (1) assessing the spatial
distribution and temporal dynamics of both species across a temperature
gradient in the northern Channel Islands, California, and (2) investigating
how the feeding rate of P. helianthoides on S. purpuratus is affected by
temperature in laboratory tests.

 

On average, at sites where mean annual temperatures were <14°C, P.
helianthoides were common, S. purpuratus was rare and kelp was persistent,
whereas where mean annual temperatures exceeded 14°C, P. helianthoides and
kelp were rare and S. purpuratus abundant. Temperature was found to be the
primary environmental factor influencing P. helianthoidesabundance, and in
turn P. helianthoides was the primary determinant of S. purpuratus
abundance. In the laboratory, temperatures >16°C (equivalent to summer
temperatures at sites where P. helianthoides were rare) reduced predation
rates regardless of predator and prey sizes, although larger sea urchins
were consumed only by large starfishes.

 

These results clearly demonstrate that the effect of P. helianthoides on S.
purpuratus is strongly mediated by temperature, and that the local abundance
and predation rate of P. helianthoides on sea urchins will likely decrease
with future warming. A reduction in top-down control on sea urchins,
combined with other expected impacts of climate change on kelp, poses
significant risks for the persistence of kelp forests in the future.

 



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