Effects of Experimental Ocean Acidification on the Larval Morphology and Metabolism of a Temperate Sparid, Chrysoblephus laticeps

Cuen Muller,Warren M Potts,Nicola C James,Amber-Robyn Childs

doi:10.3390/oceans2010002

Cuen Muller, Warren M Potts + Show 2 more

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https://doi.org/10.3390/oceans2010002

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Abstract

Ocean acidification is predicted to have widespread impacts on marine species. The early life stages of fishes, being particularly sensitive to environmental deviations, represent a critical bottleneck to recruitment. We investigated the effects of ocean acidification (∆pH = −0.4) on the oxygen consumption and morphometry during the early ontogeny of a commercially important seabream, Chrysoblephus laticeps, up until flexion. Hatchlings appeared to be tolerant to hypercapnic conditions, exhibiting no difference in oxygen consumption or morphometry between treatments, although the yolk reserves were marginally reduced in the low-pH treatment. The preflexion stages appeared to undergo metabolic depression, exhibiting lower metabolic rates along with lower growth metrics in hypercapnic conditions. However, although the sample sizes were low, the flexion-stage larvae exhibited greater rates of metabolic and growth metric increases in hypercapnic conditions. This study shows that the effects of OA may be stage specific during early ontogeny and potentially related to the development of crucial organs, such as the gills. Future studies investigating the effects of climate change on fish larvae should endeavour to include multiple developmental stages in order to make more accurate predictions on recruitment dynamics for the coming decades.

Highlights

Atmospheric carbon dioxide (CO2 ) concentrations have been rising at an increasing rate since the industrial revolution
While marine organisms will be adversely affected by ocean acidification (OA), the severity of these effects appears to be highly variable among taxa and even within taxa among life-history stages [5,6]
The metabolic rates (RMRmin, RMRroutine, RMRmax and FAS) all showed positive increases from hatching through to late preflexion, after which a separation between the treatments became evident for RMRmin and RMRroutine, in particular, with a greater rate of increase for high pCO2, while the metabolic rates for control larvae increased at a comparatively lower rate (Figure 2)

Summary

Introduction

Atmospheric carbon dioxide (CO2 ) concentrations have been rising at an increasing rate since the industrial revolution. At the current rate of change, the ocean pH may decline to levels over the 300 years not encountered over the past 300 million years [2]. Average ocean surface waters have already dropped by 0.1 units since preindustrial times and are expected to decline by a further 0.4 units by the end of the century, with coastal areas likely to experience an even greater rate of change [1,3,4]. Much of the earlier research focused on marine calcifying invertebrates, primarily due to their increased susceptibility to OA and due to the early assumption that fish would be widely tolerant to rising CO2 levels owing to their well-developed regulatory mechanisms [7,8]. Using extreme CO2 levels (greater than 10,000 μatm), early studies revealed an efficient acid–base regulatory system capable of compensating for hypercapnic disturbances [9,10]

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