Vulnerability of juvenile hermit crabs to reduced seawater pH and shading

Abstract

Multiple simultaneous stressors induced by anthropogenic activities may amplify their impacts on marine organisms. The effects of ocean acidification, in combination with other anthropogenic impacts (apart from temperature) are poorly understood, especially in coastal regions. In these areas, shading caused by infrastructure development, such as harbor construction, may potentially interact with CO2-induced pH reduction and affect invertebrate populations. Here, we evaluated the effects of reduced pH (7.6) and shading (24h in darkness) on mortality, growth, calcification and displacement behavior to live predator (danger signal) and dead gastropod (resource availability signal) odors using juveniles of the hermit crab Pagurus criniticornis collected in Araçá Bay (São Paulo state, Southeastern Brazil). After a 98 day experimental period, both stressors had a significant interaction effect on mortality, and an additive effect on total growth. No difference in calcification was recorded among treatments, indicating that individuals were able to maintain calcification under reduced pH conditions. When exposed to odor of live predators, crab responses were only affected by shading. However, an interactive effect between both stressors was observed in response to gastropod odor, leading to reduced displacement behavior. This study shows how local disturbance impacts may enhance the effects of global environmental change on intertidal crustacean populations.

Effects of Elevated pCO2 on the Survival and Growth of Portunus trituberculatus

“…The enhanced survival of swimming crabs under OA was expected and observed in this study, despite the lack of enhanced survival in other crabs (Ceballos-Osuna et al, 2013;Long et al, 2013a;Ragagnin et al, 2018;Ramaglia et al, 2018). Based on the SEM, crab survival was mainly explained by the carbonate system, antioxidative enzymes, seawater bacteria, gut bacteria, and digestive enzymes (Figure 7).…”

“…There is evidence that efficient acid-base, metabolic, and ionic regulation contributes to the compensation of extracellular pH changes, as shown in the velvet swimming crab, Necora puber (Spicer et al, 2007;Small et al, 2010), the dungeness crab, Metacarcinus magister (Hans et al, 2014), and the shore crab, Carcinus maenas (Maus et al, 2018). However, such osmoregulatory changes result in a rising energy cost and the reallocation of energy thereby compromises growth and behavior (Caldeira and Wickett, 2003;Dodd-Luke et al, 2015;Ragagnin et al, 2018). Extracellular anisosmotic regulation and intracellular isosmotic regulation have been observed in crustaceans in response to environmental osmolality changes (Ragagnin et al, 2018).…”

“…However, such osmoregulatory changes result in a rising energy cost and the reallocation of energy thereby compromises growth and behavior (Caldeira and Wickett, 2003;Dodd-Luke et al, 2015;Ragagnin et al, 2018). Extracellular anisosmotic regulation and intracellular isosmotic regulation have been observed in crustaceans in response to environmental osmolality changes (Ragagnin et al, 2018). However, OA has a depressing effect on oxygen consumption, which subsequently affects ATP production (Pörtner et al, 2004;Carter et al, 2013;Maus et al, 2018).…”

“…The impacts of OA are raising increasing concerns with regard to crustaceans because of the sensitivity of calcifying animals ( Hendriks et al, 2010 ). Among them, crabs present species-specific responses to OA, such as different impacts on calcification ( Walther et al, 2010 ; Long et al, 2013a ; Wei et al, 2015 ), and survival was shown to be reduced in crabs following a longer term exposure (months) to OA, although shorter term exposure (less than 1 month) did not have any apparent effects ( Ceballos-Osuna et al, 2013 ; Long et al, 2013a ; Ragagnin et al, 2018 ; Ramaglia et al, 2018 ). In addition, OA can also induce negative effects on crab fertilization, embryonic development, and behavior ( de la Haye et al, 2011 , 2012 ; Ceballos-Osuna et al, 2013 ; Long et al, 2013b ; Dodd-Luke et al, 2015 ).…”

Synthesis of Thresholds of Ocean Acidification Impacts on Decapods

“…Decapods are considered less sensitive to decreasing levels of carbonate saturation than are other calcifiers, because of their tightly regulated physiology and calcification process in adults, which is not directly dependent on environmental carbonate chemistry (Boßelmann et al, 2007;Taylor et al, 2015). However, the early life-history stages are particularly vulnerable to OA (Walther et al, 2010;Carter et al, 2013;Ceballos-Osuna et al, 2013;Long et al, 2013a;Small et al, 2015;Gravinese, 2018), either through maternal carryover effects (Long et al, 2016;Swiney et al, 2016) or direct effects including reduced growth rate (Allan and Maguire, 1992;Coffey et al, 2017;Ragagnin et al, 2018), increased oxidative stress and energy metabolism (Harms et al, 2014;Hu et al, 2016), exoskeleton dissolution (Bednaršek et al, 2020); reduced egg production (Kurihara et al, 2008;Meseck et al, 2016), and increased mortality (Kurihara et al, 2008;Long et al, 2013a,b;Coffey et al, 2017;Swiney et al, 2017;Tomasetti et al, 2018). Maintaining biomineralization under OA may come with high energetic costs, causing organisms to divert energy from vital physiological processes, such as reproduction (Long et al, 2013a;Meseck et al, 2016), and growth (Wood et al, 2008).…”