The importance of dietary calcium consumption in two species of semi-terrestrial grapsoid crabs

Abstract

ABSTRACT. Calcium (Ca) is essential for crustaceans, due to calcium carbonate (CaCO 3 ) deposition in the new exoskeleton to harden it. The purpose of this work was to study short term Ca balance in terms of dietary Ca ingestion in two phylogenetically related crabs (Superfamily Grapsoidea) showing different degrees of terrestrial adaptations: Sesarma rectum Randall, 1840 and Neohelice granulata (Dana, 1851). Dietary Ca ingestion was studied using purified diets with different Ca concentrations (0, 2.2 and 6.66 % Ca), together with measurements of Ca excretion and Ca hemolymph levels. The results showed that both crabs had the same response to foods containing different levels of Ca, with both species eating more of the high Ca diet. However, S. rectum consumed more per mg body mass at all Ca concentrations (6 mg.g -1 for S. rectum against 3 mg.g -1 for N. granulata). Both species excreted/egested Ca differently: S. rectum excreted Ca proportionally to ingestion, whereas N. granulata maintained constant faecal Ca output at all dietary Ca levels. Moreover, Ca hemolymph levels for crabs fed the different diets were independent of dietary Ca. In conclusion, both S. rectum and N. granulata seem to regulate the consumption of diets containing more Ca, which suggests a fine balance for Ca intake.KEYWORDS. Diet, semi-terrestrial crabs, feeding behavior, Sesarma rectum, Neohelice granulata. RESUMO. A importância do consumo de cálcio na dieta de duas espécies de caranguejos grapsóides semi-terrestres.O cálcio (Ca) é essencial para os crustáceos porque cristais de carbonato de cálcio (CaCO 3 ) são depositados no novo exoesqueleto para endurecê-lo. O objetivo do presente trabalho foi estudar o balanço do Ca em relação à sua ingestão em dois caranguejos filogenéticamente relacionados (Superfamília Grapsoidea), que apresentam diferentes graus de terrestrialidade: Sesarma rectum Randall, 1840 e Neohelice granulata (Dana, 1851). A ingestão de Ca foi estudada através do uso de dietas purificadas com diferentes quantidades de Ca (0, 2,2 e 6,66 % Ca), juntamente com a excreção de Ca nas fezes e níveis de Ca na hemolinfa. Os resultados mostraram que ambos apresentam a mesma resposta em relação aos níveis de Ca na dieta, ingerindo mais da dieta com maior quantidade de Ca. Sesarma rectum, porem, consumiu mais dieta por mg de peso para todas as concentrações de Ca utilizadas (6 mg.g -1 para S. rectum contra 3 mg.g -1 para N. granulata). As duas espécies excretaram Ca de maneira diferente: S. rectum excretou em proporção direta à quantidade ingerida, enquanto N. granulata manteve constante a excreção de Ca independente do Ca ingerido. Níveis de Ca na hemolinfa, por outro lado, foram iguais e independentes da quantidade de Ca ingerido para os dois caranguejos. Desse modo, tanto S. rectum como N. granulata parecem discriminar e ingerir dietas com maior quantidade de Ca, sugerindo uma regulação fina na ingestão do Ca.

Effect of Diet on Growth Performance of First Crab Stage Callinectes sapidus Rathbun, 1896 (Brachyura: Portunidae): A Comparison of Three Different Regimens

“…The nutritional value differs mainly in the content of calcium, nitrogen, and phosphorus (shrimp > squid > fish) [ 37 ] Calcium content in the diet can increase the growth efficiency of crabs, as shown in this study (Group 1 > Group 2 > Group 3) (*** p < 0.001). Our results showed the same growth response as in the Scylla serrata [ 38 ], Eriocheir sinensis ) [ 39 ], and superfamily Grapsoidea [ 40 ] species. Different diets with nutritional content rich in calcium can alter the frequency of molting and therefore promote the growth of crabs [ 41 ].…”

Effect of dietary supplementation of calcium chloride on growth, survival, moulting frequency and body composition of narrow-clawed crayfish,Astacus leptodactylus(Eschscholtz, 1823)

“…In intensive aquaculture, a large proportion of calcium is required to harden the new exoskeleton in crayfish (Zanotto et al . ). Calcium is stored in the exoskeleton and used when the crayfish undergoes moulting.…”

Evaluation of the stomach contents of Eriphia gonagra from a rocky shore in the southeastern Brazilian coast

“…Due to the high amount of sand found in all the sampled crabs, we do not believe that this item is there by accident. Corroborating with Pires et al (2017), who stated that Ca, in the form of calcium carbonate, in addition to chitin and proteins, is the main constituent of the structure of the crustacean exoskeleton, and Nedzarek et al (2019) who claim that Ca and Mg are elements found in high concentration in the exoskeletons; Zanotto & Pinheiro (2009) pointed out that the crab Sesarma rectum excreted crystals of calcium carbonate (CaCO3), to the new exoskeleton, in direct proportion to the amount of calcium ingested.…”