Comparative salinity tolerance in native flies from the subantarctic Kerguelen Islands: a metabolomic approach

Abstract

International audienceThe quasi-extirpation of the cabbage Pringlea antiscorbutica in some locations at the Kerguelen Islands has large impacts on the distribution of the native fly Calycopteryx moseleyi. This insect has long been supposed as being subordinant to P. antiscorbutica until both larvae and adults were observed under seaweed in littoral margins. Physiological plasticity to saline conditions is expected in C. moseleyi, and metabolic rearrangements in salt-exposed specimens should thus be similar between individuals from cabbages and seaweeds. Individuals of C. moseleyi from non-saline (cabbages) and saline (seaweeds) habitats were experimentally subjected to different salinities (0, 35, 70 practical salinity units) and compared to the widely distributed native Anatalanta aptera flies that coexist with C. moseleyi under the seaweeds. A progressive drop of the survival and body water content was observed in C. moseleyi from cabbages exposed to increasing saline conditions. Body water contents remained similar at 35 and 70 practical salinity units in C. moseleyi from seaweeds, while it did not change over the whole saline gradient in A. aptera. Metabolic profiles revealed that both fly populations from the seaweeds accumulated compatible solutes in the form of alanine or glutamic acid when they were exposed to salinity. A distinct pattern was observed in C. moseleyi specimens from cabbages, whose metabolic profiles revealed a progressive loss of metabolic homoeostasis. We conclude that the C. moseleyi specimens from the cabbages and seaweeds differentiated, as also supported by their contrasted morphotypes, and that the limited salinity tolerance of individuals from cabbages may hinder their future expansion to seaweed

Chironomidae larvae in hypersaline waters of the Crimea: diversity, distribution, abundance and production

“…), or come from food (glycerol, betaine, etc. ); this was indicated for several Diptera species (Patrick & Bradley 2000;Yoder et al 2006;Renault et al 2016). Mechanisms of osmo-regulation, as well as the synthesis of osmolytes, require a lot of energy, so obtaining osmolytes from the external environment (Yoder et al 2006) can significantly reduce the energy costs for osmoadaptation processes.…”

“…Country Lake Bulack (near Caspian Sea) (Suworow 1908) Chironomus anthracinus Zetterstedt Chironomus salinarius Kieffer, 1915 76 Mediterranean region, Aral Sea (Drake & Arias 1995;Mirabdullayev et al 2004;Velasco et al 2006) Dicrotendipes Cricotopus zavreli Szadziewski et Hirvenoja, 1981 84 Poland, Ukraine, Caucasus, Kazakhstan, Turkmenistan (Szadziewski & Hirvenoja 1981) Halocladius (Psammocladius) braunsi (Goetghebuer, 1942) 40 Europe (Hirvenoja & Der Gattung 1973) Halocladius mediterraneus Hirvenoja, 1973 63-70 Mediterranean region (Por & Ben-Tuvia 1981;El-Shabrawy & El Sayed 2005) Halocladius & Bradley 2000;Renault et al 2016). Some species can use both osmo-adaptation mechanisms together; Culex tarsalis Coquillett, 1896 can accumulate various compatible osmolytes not only in the cells but also in the body fluids (Patrick & Bradley 2000).…”

Adaptations of a native Subantarctic flightless fly to dehydration stress: more plastic than we thought? ( Short Communication)

“…Although the main habitat of this species is thought to be the native Kerguelen cabbage, it inhabits environments of contrasting characteristics. Previous studies have focused on ecophysiological adaptations to salinity (Laparie et al 2012, Renault et al 2014. Flies from two ecophenotypes, seaweeds and Kerguelen cabbages, were collected from two localities at the Kerguelen Islands (49° 26' S, 70° 26' E): Pointe Suzanne and Ile aux Cochons (Fig.…”

Chronic exposure to soil salinity in terrestrial species: Does plasticity and underlying physiology differ among specialized ground-dwelling spiders?

“…Alanine represents a common feature in several salt-exposed organisms (Patrick & Bradley 2000;Renault et al 2014), including spiders (Foucreau et al 2012). Alanine, only accumulated significantly in P. saltans and P. purbeckensis, is an important contributor of intracellular osmoregulatory processes (Holmstrup & Bayley 2013).…”