Molecular Plasticity under Ocean Warming: Proteomics and Fitness Data Provides Clues for a Better Understanding of the Thermal Tolerance in Fish.

Diana Madeira,Catarina Vinagre,Mário S Diniz,José L Capelo,Pedro M Costa,Rui Vitorino,José E Araújo

doi:10.3389/fphys.2017.00825

Abstract

Ocean warming is known to alter the performance and fitness of marine organisms albeit the proteome underpinnings of species thermal tolerance are still largely unknown. In this 1-month experiment we assessed the vulnerability of the gilt-head sea bream Sparus aurata, taken here as a biological model for some key fisheries species, to ocean warming (control 18°C, nursery ground temperature 24°C and heat wave 30°C). Survival was impaired after 28 days, mainly at 30°C although fishes' condition was unaltered. Muscle proteome modulation was assessed at 14 and 21 days, showing that protein expression profiles were similar between fish exposed to 18 and 24°C, differing from fish exposed to 30°C. Fish subjected to 24°C showed an enhanced glycolytic potential and decreased glycogenolysis mainly at 14 days of exposure. Fish subjected to 30°C also showed enhanced glycolytic potential and up-regulated proteins related to gene expression, cellular stress response (CSR), and homeostasis (mostly cytoskeletal dynamics, acid-base balance, chaperoning). However, inflammatory processes were elicited at 21 days along with a down-regulation of the tricarboxylic acid cycle. Thus, juvenile fish seem able to acclimate to 24°C but possibly not to 30°C, which is the predicted temperature for estuaries during heat waves by the year 2100. This may be related with increasing constraints on organism physiology associated with metabolic scope available for performance and fitness at higher temperatures. Consequently, recruitment of commercial sea breams may be in jeopardy, highlighting the need for improved management plans for fish stocks.

Highlights

Climate change has been associated with ecological variation, including alterations in biodiversity, abundance and distribution of species, and phenology (Parmesan and Yohe, 2003; Poloczanska et al, 2013)
These results coupled to a lack of a cellular stress response at 24◦C suggest that this temperature is not very stressful to juvenile fish; alternatively, the cellular stress response could have been induced early on in the exposure period, but if this occurred, the fish were able to repair damage and acclimate as no changes related to the stress response/tissue damage were detected
The maturation of peptide hormones probably led to the activation of molecular cascades which potentially triggered energetic adjustments necessary to induce the cellular stress response

Summary

Introduction

Climate change has been associated with ecological variation, including alterations in biodiversity, abundance and distribution of species, and phenology (Parmesan and Yohe, 2003; Poloczanska et al, 2013). Within Europe, the Iberian Peninsula and Mediterranean area are regions with an elevated rate of warming, with a predicted increase between 4 and 7◦C in air temperature by 2100 (Santos and Miranda, 2006; Christensen et al, 2007). Under such scenario, Portuguese coastal waters and the Mediterranean Sea will be 2–3◦C and 3–4◦C warmer, respectively (Miranda et al, 2002; Fischer and Schär, 2010). This will allow researchers to identify the vulnerability of key species, and stakeholders to develop appropriate mitigation plans to reduce costs to society and environment (Poloczanska et al, 2013)

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