Sea HareAplysia punctata(Mollusca: Gastropoda) Can Maintain Shell Calcification under Extreme Ocean Acidification

Abstract

Abstract. Ocean acidification is expected to cause energetic constraints upon marine calcifying organisms such as molluscs and echinoderms, because of the increased costs of building or maintaining shell material in lower pH. We examined metabolic rate, shell morphometry, and calcification in the sea hare Aplysia punctata under short-term exposure (19 days) to an extreme ocean acidification scenario (pH 7.3, ϳ2800 atm pCO 2 ), along with a group held in control conditions (pH 8.1, ϳ344 atm pCO 2 ). This gastropod and its congeners are broadly distributed and locally abundant grazers, and have an internal shell that protects the internal organs. Specimens were examined for metabolic rate via closed-chamber respirometry, followed by removal and examination of the shell under confocal microscopy. Staining using calcein determined the amount of new calcification that occurred over 6 days at the end of the acclimation period. The width of new, pre-calcified shell on the distal shell margin was also quantified as a proxy for overall shell growth. Aplysia punctata showed a 30% reduction in metabolic rate under low pH, but calcification was not affected. This species is apparently able to maintain calcification rate even under extreme low pH, and even when under the energetic constraints of lower metabolism.This finding adds to the evidence that calcification is a largely autonomous process of crystallization that occurs as long as suitable haeomocoel conditions are preserved. There was, however, evidence that the accretion of new, noncalcified shell material may have been reduced, which would lead to overall reduced shell growth under longerterm exposures to low pH independent of calcification. Our findings highlight that the chief impact of ocean acidification upon the ability of marine invertebrates to maintain their shell under low pH may be energetic constraints that hinder growth of supporting structure, rather than maintenance of calcification.

Ecophysiology and ecological limits of symbiotrophic vesicomyid bivalves (Pliocardiinae) in the Southern Ocean

“…puertodeseadoi, which is a typical response to environmental stress in temperate cold-water molluscs (e.g. Carey and Sigwart 2014;Carey et al 2016) and one other vent obligate mollusc (Sigwart and Chen 2018).…”

A review on distribution, properties, genetic organization, immobilisation and applications of urease

“…Many strains of microbes like Proteus mirabilis, Staphylococcus saprophyticus, Campylobacter pyloridis, Helicobacter pylori, Clostridium perfringens, Proteus, Klebsiella species (Rutherford, 2014), Salmonella sp., Staphylococcus aureus, Yersinia enterocolitica, Pseudomonas aeruginosa, Ureaplasma urealyticum in humans cause various diseases like urinary catheter encrustation, hepatic coma, hepatic encephalopathy, urolithiasis, pyelonephritis, Parkinson's disease and gastritis (Kataria and Khatkar, 2019). Urease activity is also found in invertebrates like Aplysia californica (Carey et al, 2016) and Land snail Otala lactea (Liu et al, 2021a). Ammonia produced due to urease activity acts as proton acceptor enhanced the biological deposition of the Calcium carbonate (Liu et al, 2021b).…”

Overcoming the constraints of spiral growth: the case of shell remodelling

“…A shell covered by the animal's tissues can still calcify even in highly acidified environments as long as it is secreted in a relatively alkaline microenvironment that is insulated from the animal's surroundings (Carey et al . 2016). If the costs of calcification limit skeletal formation, then shells should enclose as large an internal volume for a given investment in mineral deposition as possible (Graus 1974), in principle favouring an efficient use of calcium carbonate as well as mineral dissolution and recycling.…”

“…As noted in the introduction, calcification can still take place under highly acidified external conditions because the microenvironment where mineralization occurs differs from, and is more important than, the ion concentration and solubility in the animal's surroundings (see also Carey et al . 2016).…”

“…Growth rate, shell coiling and apertural shape are all determined in part by basal metabolic rate (Vermeij 2002; Lord & Shanks 2012; Carey et al . 2016), where faster metabolism enables the evolutionary exploration of a greater variety of forms and growth patterns (Vermeij 2002).…”