Development of a Halotolerant Community in the St. Lucia Estuary (South Africa) during a Hypersaline Phase

Abstract

BackgroundThe St. Lucia Estuary, Africa's largest estuarine lake, is currently experiencing unprecedented freshwater deprivation which has resulted in a northward gradient of drought effects, with hypersaline conditions in its northern lakes.Methodology/Principal FindingsThis study documents the changes that occurred in the biotic communities at False Bay from May 2010 to June 2011, in order to better understand ecosystem functioning in hypersaline habitats. Few zooplankton taxa were able to withstand the harsh environmental conditions during 2010. These were the flatworm Macrostomum sp., the harpacticoid copepod Cletocamptus confluens, the cyclopoid copepod Apocyclops cf. dengizicus and the ciliate Fabrea cf. salina. In addition to their exceptional salinity tolerance, they were involved in a remarkably simple food web. In June 2009, a bloom of an orange-pigmented cyanobacterium (Cyanothece sp.) was recorded in False Bay and persisted uninterruptedly for 18 months. Stable isotope analysis suggests that this cyanobacterium was the main prey item of F. cf. salina. This ciliate was then consumed by A. cf. dengizicus, which in turn was presumably consumed by flamingos as they flocked in the area when the copepods attained swarming densities. On the shore, cyanobacteria mats contributed to a population explosion of the staphylinid beetle Bledius pilicollis. Although zooplankton disappeared once salinities exceeded 130, many taxa are capable of producing spores or resting cysts to bridge harsh periods. The hypersaline community was disrupted by heavy summer rains in 2011, which alleviated drought conditions and resulted in a sharp increase in zooplankton stock and diversity.Conclusions/SignificanceDespite the current freshwater deprivation crisis, the False Bay region has shown to be resilient, harboring a unique biodiversity with species that are capable of enduring harsh environmental conditions. However, further freshwater deprivation may extend beyond the physiological thresholds of this community, as well as other unique biodiversity components which this system sustains.

Copepod Mandible Palynomorphs From the Nolichucky Shale (Cambrian, Tennessee): Implications for the Taphonomy and Recovery of Small Carbonaceous Fossils

“…An Apocyclops reported as A. cf. dengizicus, whose correct identity and origin needs to be verified, lives in the hypersaline St. Lucia Estuary on the east coast of South Africa (Carrasco and Perissinotto 2012).…”

“…A specific ecological character of Apocyclops is its wide spectrum of salinity tolerance (0−~100 gl -1 ), which supposedly is an evolutionarily ancient adaptation present in several lineages of the Cyclopidae to drastically changing water chemistry of the ephemeral continental waters (Löffler 1961;Hammer 1986;Dexter 1993;Timms 1993;Reid et al 2002;Pinder et al 2005;Carrasco and Perissinotto 2012). Species of Apocyclops have been found sometimes in extreme high density in inland saline lakes and coastal lagoons, pools, salt marshes, and phytotelmata (Yeatman 1983;Reid et al 2002).…”

Characteristics of meiofauna in extreme marine ecosystems: a review

“…Several nematodes and harpacticoid copepods are adapted to hypersaline conditions (Carrasco and Perissinotto 2012). In the discharge area of desalination plants in the Canary Islands, substantial changes in the abundance of nematodes and copepods have been recorded (Riera et al 2011).…”

Cyclopoida in Hypersaline Waters of the Crimea and the World: Diversity, the Impact of Environmental Factors, Ecological Role

“…dengizicus (Lepeshkin, 1900 130 Южная Африка Carrasco, Perissinotto, 2012A. dimorphus (Kiefer, 1934 45-100…”

“…При высокой солености трофическая структура сообществ упрощается и на каж-дом трофическом уровне количество ви-дов становится небольшим (Иванова, 1990;Williams, 1998;Балушкина и др., 2009;Carrasco, Perissinotto, 2012;Jia et al, 2015). …”