Combined effects of ocean acidification and temperature on larval and juvenile growth, development and swimming performance of European sea bass (Dicentrarchus labrax).

Louise Cominassi,Nicolas Le Bayon,Felix C Mark,Guy Claireaux,Sarah Howald,Marta Moyano,Myron A Peck,José-Luis Zambonino-Infante,Frank Melzner

doi:10.1371/journal.pone.0221283

Abstract

Ocean acidification and ocean warming (OAW) are simultaneously occurring and could pose ecological challenges to marine life, particularly early life stages of fish that, although they are internal calcifiers, may have poorly developed acid-base regulation. This study assessed the effect of projected OAW on key fitness traits (growth, development and swimming ability) in European sea bass (Dicentrarchus labrax) larvae and juveniles. Starting at 2 days post-hatch (dph), larvae were exposed to one of three levels of PCO2 (650, 1150, 1700 μatm; pH 8.0, 7.8, 7.6) at either a cold (15°C) or warm (20°C) temperature. Growth rate, development stage and critical swimming speed (Ucrit) were repeatedly measured as sea bass grew from 0.6 to ~10.0 (cold) or ~14.0 (warm) cm body length. Exposure to different levels of PCO2 had no significant effect on growth, development or Ucrit of larvae and juveniles. At the warmer temperature, larvae displayed faster growth and deeper bodies. Notochord flexion occurred at 0.8 and 1.2 cm and metamorphosis was completed at an age of ~45 and ~60 days post-hatch for sea bass in the warm and cold treatments, respectively. Swimming performance increased rapidly with larval development but better swimmers were observed in the cold treatment, reflecting a potential trade-off between fast grow and swimming ability. A comparison of the results of this and other studies on marine fish indicates that the effects of OAW on the growth, development and swimming ability of early life stages are species-specific and that generalizing the impacts of climate-driven warming or ocean acidification is not warranted.

Highlights

We examined the effects of ocean warming (OAW) on the somatic growth, development and swimming capacity throughout the larval and early juvenile phase of sea bass reared at two temperatures (15 ̊C and 20 ̊C) and three PCO2 levels (650, 1150, 1700 μatm; pH 8.0, 7.8, 7.6)
Larval growth rate was significantly higher at 20 ̊C compared to 15 ̊C (p < 0.001), but there was no significant effect of PCO2 treatment (p = 0.120) (Fig 1)
Our results indicate that, when fed ad libitum, European sea bass larvae are not impacted by projected future increases in levels of PCO2 thanks to the use of physiological mechanisms allowing them to maintain growth and swimming performance

Summary

Methods

The present work was performed within Ifremer-Centre de Bretagne facilities (agreement number: B29-212-05). Sea bass juveniles and adults are usually found in coastal waters and estuaries where the impact of PCO2 might be exacerbated [35, 36]. 2014 [37] reported PCO2 values >2000 μatm in northeast US estuaries, while values up to 3000 μatm were recorded in coastal areas of the SW Baltic Sea [38] Based on those data, and PCO2 values of European estuaries provided by Frankignoulle et al, 1998 [39], a higher CO2 treatment of Δ1000 μatm from ambient level Larvae were reared at 15 ̊C and juveniles experienced 15 to 18 ̊C (natural, seasonal differences reflecting ambient summer conditions in the Bay of Brest (see http://marc.ifremer.fr/en/results/ temperature_and_salinity/mars3d_channel_bay_of_biscay_model/(typevisu)/map/(zoneid)/ sudbzh#appTop) [40, 41]. Juveniles enter estuaries in the late spring and grow in these waters through the summer months [43, 44]

Results

Discussion

Conclusion