Medium-term exposure of the North Atlantic copepod <i>Calanus finmarchicus</i> (Gunnerus, 1770) to CO<sub>2</sub>-acidified seawater: effects on survival and development

Abstract

Abstract. The impact of medium-term exposure to CO 2 -acidified seawater on survival, growth and development was investigated in the North Atlantic copepod Calanus finmarchicus. Using a custom developed experimental system, fertilized eggs and subsequent development stages were exposed to normal seawater (390 ppm CO 2 ) or one of three different levels of CO 2 -induced acidification (3300, 7300, 9700 ppm CO 2 ). Following the 28-day exposure period, survival was found to be unaffected by exposure to 3300 ppm CO 2 , but significantly reduced at 7300 and 9700 ppm CO 2 . Also, the proportion of copepodite stages IV to VI observed in the different treatments was significantly affected in a manner that may indicate a CO 2 -induced retardation of the rate of ontogenetic development. Morphometric analysis revealed a significant increase in size (prosome length) and lipid storage volume in stage IV copepodites exposed to 3300 ppm CO 2 and reduced size in stage III copepodites exposed to 7300 ppm CO 2 . Together, the findings indicate that a pCO 2 level ≤ 2000 ppm (the highest CO 2 level expected by the year 2300) will probably not directly affect survival in C. finmarchicus. Longer term experiments at more moderate CO 2 levels are, however, necessary before the possibility that growth and development may be affected below 2000 ppm CO 2 can be ruled out.

Analyzing the Impacts of Elevated-CO2 Levels on the Development of a Subtropical Zooplankton Community During Oligotrophic Conditions and Simulated Upwelling

“…These results are in line with previous studies in calanoid copepods which also observed a decrease in copepod size (Garzke et al, 2015) and fecundity loss (Thor and Dupont, 2015) caused by increased CO 2 levels. However, unlike the major sensitivities to OA previously described for early life stages of calanoid copepods (Pedersen et al, 2013;Algueró-Muñiz et al, 2017), we did not observe a stronger pCO 2 effect on Oncaea copepodites than on adults (Figure 5), suggesting differences between poecilostomatoids and calanoids in their offspring responses to expected future OA levels. We conclude that the negative pCO 2 effect detected on Oncaea females' reproductive output might affect food web interactions in the long term in those tropical and subtropical communities dominated by this species (e.g., Böttger-Schnack, 1994), especially in those where oncaeid copepods are the main prey for larvae and juvenile fish (Itoh et al, 2014).…”

The metabolic response of marine copepods to environmental warming and ocean acidification in the absence of food

“…Animals that regularly face exposure to variable seawater temperature and p CO 2 are hypothesized to be more resilient to the effects of ocean acidification and warming owing to the necessity for physiological adaptations 34 35 . The observation that vertically migrating copepods, including a variety of Calanus spp., appear to be robust to end of century climate scenarios 33 lends weight to this understanding; b) Previous studies have demonstrated that rates of respiration, biomass turnover and lipid accumulation in C. finmarchicus exposed to CO 2 -acidified seawater at pH 7.3–~6.9 do not differ to their values in the corresponding control treatments 22 36 37 . Experiments in which sub-adults and females of the congeners, Calanus glacialis and Calanus hyperboreus, were exposed to 3000 μatm p CO 2 (pH ~7.3) also failed to discern treatment effects on the rates of respiration and biomass turnover 38 ; c) Gonad development and egg production in Calanus spp.…”

“…Future warming and ocean acidification scenarios are both reported to affect the development and reproductive potential of Calanus spp. 20 21 22 . We are unaware of any studies that have simultaneously examined how warming and acidification affect metabolic processes and hence the performance of these animals.…”

Ocean and Coastal Acidification off New England and Nova Scotia

“…Copepods appear to be relatively robust to atmospheric pCO 2 levels up to about 3,500 ppm (Ω < 1.0). For example, Calanus finmarchicus survival is not affected by pCO 2 levels less than 7,000 ppm (Pedersen et al, 2013(Pedersen et al, , 2014 and survival of Acartia tonsa copepo dites and adults is not affected by pCO 2 levels less than 3,000 ppm, although the A. tonsa naupliar mortality rate increases at 1,000 µatm (Cripps et al, 2014). In con trast to copepods, pteropods are highly sensitive to increased pCO 2 conditions (Bednaršek et al, 2014).…”