A positive temperature‐dependent effect of elevated CO₂ on growth and lipid accumulation in the planktonic copepod, Calanus finmarchicus

Abstract

Calanus finmarchicus were reared from eggs to adults at 12 C and 16 C with non-limiting food in combination with ambient (600 μatm) and high (1100 μatm) pCO 2 . These conditions are likely to be encountered by the species at the southern margins of its biogeographical range by the end of the century. Dry weight (DW), carbon (C) and nitrogen (N) mass, oil-sac volume (OSV), fatty acid composition (FA), and oxygen consumption rates (OCR) were measured on newly molted stage CV copepodites and recently molted adult females. By focusing our measurements on these precise events in the life cycle, we were able to obtain a more accurate comparison of growth and respiration across treatments. Copepods raised at 12 C had a significantly greater DW, OSV, and C and N mass than those raised at 16 C High pCO 2 , independent of temperature, was associated with a further increase in the DW and C content of the copepods. Interactive effects of temperature and pCO 2 resulted in a larger OSV at low temperature and high pCO 2 . Mass-specific respiration rates were significantly lower at lower temperatures and elevated pCO 2 suggesting that the increase in mass (DW, C, and OSV) resulted from reduced metabolic cost. The composition of fatty acids in the copepods varied mainly with temperature. Two fatty acids varied with pCO 2 : 16:0 tended to decrease with higher pCO 2 and 18:3nÀ3 tended to increase with higher pCO 2 . These observations suggest that elevated pCO 2 /lower pH in future oceans may have a beneficial effect on C. finmarchicus.

Cascading, interactive, and indirect effects of climate change on aquatic communities, habitats, and ecosystems

“…Interestingly, variance among sampling sites increased over time, indicating differences in recovery capacity and stressing the need for long-term observations. The results of Lange et al (2023) emphasizing species-specific differences in responses parallel the findings of several other studies documenting speciesspecific physiology and behavior in zooplankton, including Bomfim et al (2023), Carrier-Belleau et al (2023, Ramondenc et al (2023), andFields et al (2023), documenting zooplankton species specific physiology and ecology. Similarly, Meyer-Gutbrod et al (2023) showed that right whale pod identity is critically important, and Su et al (2023) concluded that location and species were critical to the differential results in their aquaculture lake study.…”

“…Even different life cycle stages of the same species responded uniquely to environmental drivers. Fields et al (2023) found differences in copepod responses at different developmental stages when subject to manipulated temperature and pCO 2 treatments. These life‐stage specific differences have direct implications for the nutritional value of these zooplankton to higher trophic levels.…”

“…It is a strength of this special issue to be representative of diverse habitats and scales, including alpine streams (Leathers et al 2023), wetlands of the North American Great Plains (Hu et al 2023), lakes (Hébert et al 2023; Katkov and Fussmann 2023; Su et al 2023), estuaries (Douglas et al 2023; Franzè et al 2023), tropical reefs (Lange et al 2023), and the arctic ocean (Ramondenc et al 2023), as well as diverse organisms, from single celled algal primary producers (Vrana et al 2023) to top consumers such as right whales (Meyer‐Gutbrod et al 2023). Moreover, contributions cover ecologically and climate‐relevant ranges of scales, including laboratory experimentation lasting days (Bomfim et al 2023; Carrier‐Bellau et al 2023, Fields et al 2023), mesocosm experiments of 1‐month duration (Katkov & Fussmann 2023; Wang et al 2023), as well as the paleorecord (Hu et al 2023). Despite this diversity of habitats and scales, the contributions to the special issue reflect only a subset of breadth, approaches, and geographic coverage; several gaps in contributions of climate‐oriented aquatic research are apparent.…”

“…As highlighted above, such shifts in nutritional value have significant consequences for top predators and can even affect their migration and distribution patterns (Meyer‐Gutbrod et al 2023). Knowledge of changes in carbonate chemistry and sea surface temperatures, particularly in the rapidly warming Northwest Atlantic, along with details of the foraging habitat of right whales elucidated by Meyer‐Gutbrod et al (2023), can be combined with the insights gained by Fields et al (2023) to anticipate future changes to the prey quantity and quality for right whales. The coastal region of the Northeast United States has one of the fastest rates of warming observed globally, along with substantive changes to biodiversity (Thomas et al 2017; Blowes et al 2019).…”

“…Two studies, also from the Atlantic, particularly exemplify how species-specific responses can empower understanding across scales and trophic levels. Fields et al (2023) asked how the direct and interactive effects of potential climate stressors on different life stages of crustacean zooplankton altered vital rates and growth potential. In their two-factor study, temperature and pCO 2 had opposite effects.…”