How does rising atmospheric CO2 affect marine organisms?

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Seahorses in a Future Warmer World
Aurelio, M., Faleiro, F., Lopes, V.M., Pires, V., Lopes, A.R., Pimentel, M.S., Repolho, T., Baptista, M., Narciso, L. and Rosa, R. 2013. Physiological and behavioral responses of temperate seahorses (Hippocampus guttulatus) to environmental warming. Marine Biology 160: 2663-2670.

Since it had never been done before, the purpose of this study, in the words of the authors, "was to evaluate, for the first time, the effect of environmental warming on the metabolic and behavioral ecology of a temperate seahorse, Hippocampus guttulatus."

What was done
As described by Aurelio et al., they compared routine metabolic rates, thermal sensitivity, ventilation rates, food intake and behavioral patterns at the average spring temperature (18°C), the average summer temperature (26°C), the temperature that seahorses often experience during summer heat wave events (28°C), and the temperature of a near-future warming (+2°C) scenario (= 30°C) in Portugal's Sado estuary.

What was learned
The ten scientists found that (1) "both newborn juveniles and adults showed significant increases in metabolic rates with rising temperatures," with newborn juveniles being "more impacted by future warming via metabolic depression," that (2) "in adult stages, ventilation rates also increased significantly with environmental warming, but food intake remained unchanged," and that (3) "the frequency of swimming, foraging, swinging, and inactivity did not significantly change between the different thermal scenarios."

What it means
In light of these several findings, Aurelio et al. concluded that "adult seahorses show great resilience to heat stress and are not expected to go through any physiological impairment and behavioral change with the projected near-future warming," but they note that juveniles in their early life stages "display greater thermal sensitivity and may face greater metabolic challenges," the outcome of which remains unknown.

Reviewed 8 January 2014