Eco-physiological responses of copepods and pteropods to ocean warming and acidification

Abstract

We compare physiological responses of the crustacean copepod Calanus pacificus and pelagic pteropod mollusk Limacina helicina to ocean temperatures and pH by measuring biomarkers of oxidative stress, antioxidant defences, and the activity of the respiratory electron transport system in organisms collected on the 2016 West Coast Ocean Acidification cruise in the California Current System. Copepods and pteropods exhibited strong but divergent responses in the same habitat; copepods had higher oxygen-reactive absorbance capacity, glutathione-S-transferase, and total glutathione content. The ratio between reduced to oxidised glutathione was higher in copepods than in pteropods, indicating lower oxidative stress in copepods. Pteropods showed higher activities of glutathione reductase, catalase, and lipid peroxidation, indicating increased antioxidant defences and oxidative stress. Thus, the antioxidant defence system of the copepods has a greater capacity to respond to oxidative stress, while pteropods already face severe stress and show limited capacity to deal with further changes. The results suggest that copepods have higher adaptive potential, owing to their stronger vertical migration behaviour and efficient glutathione metabolism, whereas pteropods run the risk of oxidative stress and mortality under high CO2 conditions. Our results provide a unique dataset and evidence of stress-inducing mechanisms behind pteropod ocean acidification responses.

Copepod reproductive effort and oxidative status as responses to warming in the marine environment

“…They experience strong environmental variability on daily, seasonal, and annual scale, as their diel vertical migration behavior exposes them to a large gradient of physicochemical conditions, such as temperature, salinity, and pH (Almén et al, 2014;Engström-Öst et al, 2019;Lewis et al, 2013). Thus, copepods have traditionally been considered fairly robust to environmental changes, but can be quite sensitive to thermal changes (Garzke et al, 2020;Vehmaa et al, 2013), whereas are less sensitive to pH and slight ocean acidification (Engström-Öst et al, 2019(Engström-Öst et al, , 2020Niehoff et al, 2013). UV light can also cause DNA damage and oxidative stress in zooplankton, especially in clear waterbodies (Tartarotti et al, 2014).…”

Chemical Exposure Due to Anthropogenic Ocean Acidification Increases Risks for Estuarine Calcifiers in the Salish Sea: Biogeochemical Model Scenarios

“…Furthermore, synthesis and metaanalyses work indicate a much broader vulnerability with the ultimate impact on marine ecosystems (Kroeker et al, 2013;Busch and McElhany, 2016). Moreover, the impact is noticeable under present-day conditions, with field studies delineating effects in some of the most vulnerable marine species, such as oysters (Barton et al, 2012(Barton et al, , 2015, copepods (Engström-Öst et al, 2019), foraminifera (Osborne et al, 2016(Osborne et al, , 2020, pteropods (Bednaršek et al, 2014(Bednaršek et al, , 2016(Bednaršek et al, , 2017a(Bednaršek et al, , 2018(Bednaršek et al, , 2019Feely et al, 2016) and Dungeness crab larvae (Bednaršek et al, 2020). For the last three species in particular, robust attribution analyses have unequivocally demonstrated the impact of anthropogenic OA as a driver behind observed negative responses (Bednaršek et al, 2014(Bednaršek et al, , 2020Osborne et al, 2020).…”

The effects of low pH on the taste and amino acid composition of tiger shrimp

“…Sulphur amino acids (methionine and cysteine) play important roles on oxidative stress resistant enzyme expression. While invertebrate expose to acidic water, higher oxidative stress (superoxide, reactive oxygen species) was detected in their tissue 40 , 41 . The decreased of methionine observed in our study, results in lower methionine metabolism affect low expression of cysteine 42 , 43 .…”