Multigenerational Exposure to Ocean Acidification during Food Limitation Reveals Consequences for Copepod Scope for Growth and Vital Rates

Abstract

29The copepod Calanus finmarchicus is a key component of northern Atlantic food webs, linking 30 energy-transfer from phytoplankton to higher trophic levels. We examined the effect of different 53The carbonate concentration in seawater is declining due to increased pCO2 4 , and meta-analyses 54 indicate that calcifying organisms may be negatively affected by this phenomenon 5 . Marine 55 metazoans rely on a positive CO2 gradient from their body fluids to excrete metabolic CO2 by 56 diffusion. Elevated seawater pCO2 can therefore lead to hypercapnia and acidosis 6 which in turn 57 may result in a reallocation of resources away from growth and reproduction, due to mobilization 58 of energy demanding acid-base regulatory processes to counteract internal pH reduction. 59Accordingly, ocean acidification has been shown to negatively affect processes such as 60 reproduction 7 , development 8 and behavior 9 in non-calcifying organisms also. 61Copepods of the genus Calanus constitute a large part of the zooplankton biomass in the North 62 Atlantic 10, 11 . During the development from eggs, these copepods develop through six nauplii 63 stages (N1-N6), of which the two first (N1-2) are non-feeding, and five copepodite stages (C1-64 C5), before reaching maturity as either male or female 12 . These cold water species concentrate 65 and store energy through synthesis and accumulation of lipids and therefore represent an 66 important energy link between phytoplankton and higher trophic level predators such as fish 13, 14 67

Seawater pH Predicted for the Year 2100 Affects the Metabolic Response to Feeding in Copepodites of the Arctic Copepod Calanus glacialis

“…finmarchicus do not respond to OA in the range tested here. While metabolic rates were found to increase linearly in a very wide range of OA from pH T 8.02 to pH T 7.16 in culture reared CVs of this species [57], this change would not be sufficient to create any significant difference by the OA scenario tested in the present study (pH T 8.10–7.70). Accordingly, wild caught C .…”

Ocean acidification effects on mesozooplankton community development: Results from a long-term mesocosm experiment

“…Previously, copepods were considered to be relatively tolerant to OA [26, 27], but several processes in copepods may in fact be affected by low pH, including metabolism [28], pH balance [29], reproduction [30], development [31], growth [32] and survival [33]. Furthermore, diverse sensitivities to OA exist between different species and even between life stages within species [34].…”

Development of Euphausia pacifica (krill) larvae is impaired under pCO2 levels currently observed in the Northeast Pacific

“…OA is happening at a faster rate than at any time during the past 50 million years (Hön isch et al 2012) and has the potential to affect marine ecosystems throughout the world (Hofmann et al 2010, Kroeker et al 2013. Increased CO 2 affects both calcification and acid−base physiology in marine organisms; in some species, the increased metabolic costs of compensating for decreased pH can divert energy away from growth and reproduction (Melzner et al 2011, Thomsen et al 2013, Pedersen et al 2014. In general, increased CO 2 decreases survival, calcification, growth, and development in marine invertebrates, but with highly variable responses among different groups (Kroeker et al 2013).…”