Effects of high pCO2 on Tanner crab reproduction and early life history—Part I: long-term exposure reduces hatching success and female calcification, and alters embryonic development

Abstract

Ocean acidification, a decrease in ocean pH due to absorption of anthropogenic atmospheric CO2, has variable effects on different species. To examine the effects of long-term exposure on Tanner crab (Chionoecetes bairdi) embryonic development, hatching success, and calcification, ovigerous females were reared in one of three treatments: ambient pH (∼8.1), pH 7.8, and pH 7.5 for 2 years. Embryos and larvae in year 1 were from oocytes developed in the field and appear resilient to high pCO2. Embryos and larvae in year 2 were from oocytes developed under high pCO2 conditions. Oocyte development appears sensitive to high pCO2, effects carryover and altered embryonic development, and reduced hatching success with on average 71% fewer viable larvae hatched in the pH 7.5 treatment than in the other treatments. Per cent calcium was reduced among females exposed to pH 7.5 waters, and their carapaces were noticeably more pliable than those in the other treatments. Softer carapaces may result in reduced defences against predators, and a reduction in the ability to feed on prey with hard parts such as shells. The results from this long-term study suggest that projected ocean pH levels within the next two centuries will likely have a pronounced impact on Tanner crab populations unless the crab are able to acclimatize or adapt to changing conditions.

Stress physiology and weapon integrity of intertidal mantis shrimp under future ocean conditions

“…We therefore view N. bredini as a model system for understanding why and how some organisms can better tolerate simulated ocean acidification and warming while others cannot. It is also widely recognized that the early developmental stages of crustaceans, such as tanner crabs, lobsters, shrimp, and krill, can be detrimentally effected by high pCO 2 conditions and have carry-over effects on later life history stages5354555657. Adult mantis shrimp could be similarly affected by their past environmental history, which merits further study.…”

The effects of elevated temperature and PCO2 on the energetics and haemolymph pH homeostasis of juveniles of the European lobster, Homarus gammarus

“…The short exposure time of the present study (14 days) suggests that at 13°C, H. gammarus juveniles can effectively cope with extreme levels of P CO2 ; however, over longer time frames this may come at some cost, e.g. carapace demineralisation and subsequent increase in moultrelated mortalities (Small et al, 2016b;Swiney et al, 2016), as seen in other marine invertebrates (Wood et al, 2008(Wood et al, , 2010.…”

“…If we are to understand the effects of complex global change scenarios on marine organisms, we need to understand what makes some species tolerant and others susceptible (Widdicombe and Spicer, 2008): a concept that must also be applied to different life history stages, such as those of the lobster species studied here, to acquire a more comprehensive understanding of species sensitivity to global change (e.g. Long et al, 2013;Small et al, 2016b;Swiney et al, 2016). The aim of the present study was to investigate the ability of early benthic juvenile Homarus gammarus to regulate haemolymph acid-base status when challenged with elevated P CO2 levels at both current and elevated environmental temperatures, whilst maintaining a positive energy metabolism.…”

No compromise between metabolism and behavior of decorator crabs in reduced pH conditions

“…Within crustaceans, the effects are highly variable and the data are still too limited to resolve general patterns, if they exist. Consider that calcification, one of the most commonly measured responses, decreases under reduced pH conditions for some crustacean species and life stages 6–8 , yet increases in others 9–11 , or remains unchanged 1,12–16 . The root of this variability remains unclear, though current hypotheses suggest that the most vulnerable species may be those that are poor osmoregulators, are inactive with low metabolisms, and inhabit stable environments 1,17,18 .…”

“…It is a common argument that increased energy demand to cope with a stressful environment may leave animals, both osmoregulators and osmoconformers, with insufficient energy to perform all of their normal physiological processes and behaviors, resulting in trade-offs in energy allocation. This is evident in species that experience reduced growth rates 6 , changes in calcification 8 , and reduced swimming performance 26 under reduced pH conditions. The energy and metabolic costs of responding to reduced pH has been studied in some species 20 , but typically not in combination with other physiological processes and behaviors that may be compromised.…”