Loading...
3 results
Search Results
Now showing 1 - 3 of 3
- Neuro-oxidative damage and aerobic potential loss of sharks under elevated CO2 and warmingPublication . Rosa, Rui; Paula, José Ricardo; Sampaio, Eduardo; Pimentel, Marta; Lopes, Ana Rita; Baptista, Miguel; Guerreiro, Miguel; Santos, Catarina; Campos, Derek; Almeida-Val, Vera M.F.; Calado, Ricardo; Diniz, Mário; Repolho, TiagoSharks occupy high trophic levels in marine habitats and play a key role in the structure and function of marine communities. Their populations have been declining worldwide by ≥90 %, and their adaptive potential to future ocean conditions is believed to be limiting. Here we experimentally exposed recently hatched bamboo shark (Chiloscyllium punctatum) to the combined effects of tropical ocean warming (+4; 30 °C) and acidification (ΔpH 0.5) and investigated the respiratory, neuronal and antioxidant enzymatic machinery responses. Thirty days post-hatching, juvenile sharks revealed a significant decrease in brain aerobic potential (citrate synthase activity), in opposition to the anaerobic capacity (lactate dehydrogenase). Also, an array of antioxidant enzymes (glutathione S-transferase, superoxide dismutase activity and catalase) acted in concert to detoxify ROS, but this significant upregulation was not enough to minimize the increase in brain’s peroxidative damage and cholinergic neurotransmission. We argue that the future conditions may elicit deleterious deficiencies in sharks’ critical biological processes which, at the long-term, may have detrimental cascading effects at population and ecosystem levels.
- Deficit in digestive capabilities of bamboo shark early stages under climate changePublication . Rosa, Rui; Pimentel, Marta; Galan, Juan; Baptista, Miguel; Lopes, Vanessa M.; Couto, Ana; Guerreiro, Miguel; Sampaio, Eduardo; Castro, Joana; Santos, Catarina; Calado, Ricardo; Repolho, TiagoLittle empirical information is currently available on the potential effects of acidification and/or warming in sharks, but none exist about digestive capabilities under such future conditions. Here, we investigated the impact of both acidification (ΔpH = 0.5) and warming (+4; 30 °C) on the digestive enzyme levels of recently hatched tropical bamboo shark (Chiloscyllium punctatum). Thirty days post-hatching, juvenile sharks revealed a significant increase in pancreatic trypsin levels under warming, but also a significant decrease under acidification, namely a 42 % drop under present-day temperature and 44 % drop under the warming condition. A similar trend was recorded for the alkaline phosphatase activity in shark’s intestine, i.e. the impact of environmental hypercapnia was also quite notorious—a 50 % drop under present-day temperature and 49 % drop under the warming condition. Thus, our present findings suggest that acidification and warming acted antagonistically, leading to similar enzyme activities under present and future conditions. Future directions on this topic of research should point towards the study of other types of sharks, namely pelagic ones with quite higher energetic demands.
- Seahorses under a changing ocean: the impact of warming and acidification on the behaviour and physiology of a poor-swimming bony-armoured fishPublication . Faleiro, Filipa; Baptista, Miguel; Santos, Catarina; Aurelio, Maria; Pimentel, Marta; Pegado, Maria Rita; Paula, José Ricardo; Calado, Ricardo; Repolho, Tiago; Rosa, RuiSeahorses 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.