Seahorses under a changing ocean: the impact of warming and acidification on the behaviour and physiology of a poor-swimming bony-armoured fish.

Filipa Faleiro,Miguel Baptista,Rui Rosa,Catarina Santos,Tiago Repolho,José Ricardo Paula,Ricardo Calado,Marta Pimentel,Maria Rita Pegado,Maria L Aurélio

doi:10.1093/conphys/cov009

Filipa Faleiro, Miguel Baptista + Show 8 more

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https://doi.org/10.1093/conphys/cov009

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Abstract

Seahorses are currently facing great challenges in the wild, including habitat degradation and overexploitation, and how they will endure additional stress from rapid climate change has yet to be determined. Unlike most fishes, the poor swimming skills of seahorses, along with the ecological and biological constraints of their unique lifestyle, place great weight on their physiological ability to cope with climate changes. In the present study, we evaluate the effects of ocean warming (+4°C) and acidification (ΔpH = -0.5 units) on the physiological and behavioural ecology of adult temperate seahorses, Hippocampus guttulatus. Adult seahorses were found to be relatively well prepared to face future changes in ocean temperature, but not the combined effect of warming and acidification. Seahorse metabolism increased normally with warming, and behavioural and feeding responses were not significantly affected. However, during hypercapnia the seahorses exhibited signs of lethargy (i.e. reduced activity levels) combined with a reduction of feeding and ventilation rates. Nonetheless, metabolic rates were not significantly affected. Future ocean changes, particularly ocean acidification, may further threaten seahorse conservation, turning these charismatic fishes into important flagship species for global climate change issues.

Highlights

Seahorses are charismatic fishes that catch people’s attention with their unusual beauty and unique lifestyle
We evaluate the effects of ocean warming (+4°C) and acidification (ΔpH = −0.5 unit) on the metabolism, ventilation rate, feed intake and behavioural patterns of adult temperate seahorses, Hippocampus guttulatus, in order to understand how these fish will respond to future changes in ocean temperature and chemistry
Ocean warming and acidification had a significant impact on the metabolism of H. guttulatus (Fig. 1 and Supplementary Table S2)

Summary

Introduction

Seahorses are charismatic fishes that catch people’s attention with their unusual beauty and unique lifestyle They are admired and sought all around the world, with millions of seahorses being traded every year for traditional medicine, aquarium and curio trade (Lourie et al, 2004). Many seahorse species are currently threatened worldwide by intensive exploitation and overfishing, as well as by the widespread degradation of their natural habitats. Seahorses were included both in the IUCN Red List of Threatened Species and in the Appendix II of CITES, as well as in some regional and national lists of threatened species (Vincent et al, 2011).

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