Zoological Studies

Vol. 57, 2018

(update: 2018.07.03; 08.08) 

Salinity Variation in a Mangrove Ecosystem: A Physiological Investigation to Assess Potential Consequences of Salinity Disturbances on Mangrove Crabs

Dimitri Theuerkauff1,2,#, Georgina A. Rivera-Ingraham1,#, Jonathan A.C. Roques1,2, Laurence Azzopardi1,2, Marine Bertini1, Mathilde Lejeune1, Emilie Farcy1, Jehan-Hervé Lignot1,*, and Elliott Sucré1,2

1UMR MARBEC (University of Montpellier, CNRS, IFREMER, IRD), Montpellier, France. E-mail: Dimitri.theuerkauff@umontpellier.fr (Theuerkauff); g.rivera-ingraham@gmail.com (Rivera-Ingraham); Jonathan.roques@bioenv.gu.se (Roques); Laurence.azzopardi@univ-mayotte.fr (Azzopardi); Marine.bertini@umontpellier.fr (Bertini); Emilie.farcy@umontpellier.fr (Farcy); Elliott.sucre@univ-mayotte.fr (Sucré)
2Centre Universitaire de Mayotte (CUFR), Route Nationale 3, BP 53, 97660 Dembeni, Mayotte, France

(Received 14 December 2017; Accepted 21 June 2018; Communicated by Benny K.K. Chan)

Theuerkauff, Georgina A. Rivera-Ingraham, Jonathan A.C. Roques, Laurence Azzopardi, Marine Bertini, Mathilde Lejeune, Emilie Farcy, Jehan-Hervé Lignot, and Elliott Sucré (2018) Salinity is one of the main environmental factors determining coastal species distribution. However, in the specific case of mangrove crabs, salinity selection cannot be understood through ecological approaches alone. Yet understanding this issue is crucial in the context of mangrove conservation, since this ecosystem is often used as biofilter of (low-salinity) wastewater. Crabs are keystone species in this mangrove ecosystem and are differentially affected by salinity. We hypothesize that crab salinity selection may be partly explained by specific salinity-induced physiological constraints associated with osmoregulation, energy and redox homeostasis. To test this, the response to salinity variation was analysed in two landward mangrove crabs: the fiddler crab Tubuca urvillei, which inhabits low-salinity areas of the mangrove, and the red mangrove crab Neosarmatium meinerti, which lives in areas with higher salinity. Results confirm that both species are strong hypo-/hyper-osmoregulators that deal easily with large salinity variations. Such shifts in salinity do not induce changes in energy expenditure (measured as oxygen consumption) or in the production of reactive oxygen species. However, T. urvillei is physiologically suited to habitats with brackish water, since it presents i) high hemolymph osmolalities over a wider range of salinities and lower osmoregulatory capacity in seawater, ii) high Na+/K+-ATPase (NKA) activity in the posterior osmoregulatory gills and iii) a thicker osmoregulatory epithelium along the posterior gill lamellae. Therefore, while environmental salinity alone cannot directly explain fiddler and red mangrove crab distributions, our data suggest that salinity selection is indeed influenced by specific physiological adjustments.

Key words: Bioenergetics, Osmoregulation, Salinity-induced oxidative stress, Mangrove, Decapods.

*Correspondence: E-mail: jehan-herve.lignot@umontpellier.fr
#Dimitri Theuerkauff and Georgina A. Rivera-Ingraham contributed equally to this work.