Effects of ocean warming and acidification on the early stages of marine fishes

The potential susceptibility of fish species to climate-driven changes as been highlighted by an increasing number of studies, yet little is known about fish earlylife stages capacity to tolerate future ocean conditions. In this context, the main objectives of this dissertation were to investigate a comprehensive set of biological responses of early-life stages of commercially important fish species with different life strategies, seabream (Sparus aurata), meagre (Argyrosomus regius), Senegalese sole (Solea senegalensis) and dolphinfish (Coryphaena hippurus) to future ocean warming (+4°C) and acidification (ΔpH=0.5) expected for 2100. The current dissertation constitutes the first attempt to address the interacting effects of climate-related conditions in fish early ontogeny. The combination of ocean warming and acidification intensified the effects on many morphological, behavioural, biochemical and physiological features, namely hatching success, skeletal deformities, growth, metabolic and enzymatic profiles, heat shock and antioxidant responses. However, species tolerance to future conditions was shown to be species-specific. Changes on the different features here investigated had severe repercussions on larval survival rates of each fish species. Impacts revealed to be more deleterious for seabream and meagre, the most active species with an
associated planktonic life strategy. The higher decrease in survival rates of these species, 51.92% and 50.00% respectively, suggests a lower tolerance than the benthic flatfish (28.44% decrease) to future climate change. Such impairments are expected to affect larval performance, recruitment success, and further influence the abundance of fish stocks and population structure of these species. The main outputs of this dissertation allow stakeholders and policy-makers to take proactive measures to protect endangered and commercially-important species. However, it is worth noting that these species may have the opportunity to adapt to future ocean conditions.

Pimentel da Silva M. C. S., 2016. Effects of ocean warming and acidification on the early stages of marine fishes. PhD thesis, University of Lisbon, 192 p. Thesis.

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