Correspondence of the Seasonal Patterns of the Brine Shrimp, Artemia Salina (Leach, 1819) (Anostraca) with Several Environmental Factors in an Arid Solar Saltern (Sfax, Southern Tunisia)

Abstract

We investigated the correspondence of the seasonal patterns of Artemia salina with several environmental factors along a natural salinity gradient in four ponds (M1, M2, M3, and B1) located in the arid solar saltern of Sfax (southern Tunisia). The shape of the frontal knobs of males showed the dominance of the autochthonous species, A. salina. Artemia abundance and fecundity were assessed. Biometrics of A. salina stages were studied by comparing cyst size and body length. A. salina abundance displayed a clear seasonal and spatial variation. Abundance of live Artemia ranged between 0.25 × 10 3 and 1414 × 10 3 ind m −3 . The highest numbers were recorded in pond M3, as nauplii (771.8×10 3 ind m −3 corresponding to 31.8 g m −3 ). This resulted from low male and female numbers (34 and 17 × 10 3 ind m −3 , respectively). Artemia cysts were predominant (92.96% of total Artemia), and grouped in small (216 μm) and large (243 μm) sized cysts, which correlated negatively with temperature (r = −0.4, N = 294, p < 0.01) and salinity (r = −0.39, N = 294, p < 0.01), and positively with female fecundity (r = 0.6, p < 0.05). The large (270 μm) and small (216 μm) cysts suggested the presence of also the species A. parthenogenetica and A. franciscana in the saltern, respectively. Fecundity showed a summer-autumn distribution that correlated significantly (−0.6 and −0.9, N = 35, p < 0.01) with both temperature and salinity. A. salina performed best in M2 (more than 80 cysts per brood), at about 200 g l −1 and 26.8 • C, with gravid females representing 20%. A. salina from the Sfax solar saltern was unable to withstand extreme temperatures (35 • C), but tolerated extreme salinity (330 g l −1 ). Abundance, biometrics, and reproductive descriptors of A. salina appeared to be governed chiefly by temperature and salinity, the physical structure of the saltern, and food availability, such as the unicellular green alga, Dunaliella salina. Nauplii (mean length: 401 μm) from small-sized cysts encountered in the saltern might be a valuable food source for hatcheries of some small-mouthed marine fish. RÉSUMÉ La distribution spatio-temporelle d'Artemia salina couplée aux facteurs environnementaux a été étudiée dans quatre bassins de salinité croissante M1, M2, M3 et B1 de la saline de Sfax (Sud de Tunisie). La forme du lobe frontal des mâles d'Artemia montre la dominance de l'espèce autochtone A. salina. L'abondance, la fécondité et la biométrie des différents stades d'Artemia ont été estimées en comparant le diamètre des cystes et les longueurs des autres stades. L'abondance d'A. salina montre une nette variation spatio-temporelle. La densité d'Artemia varie entre 0,25×10 3 et 1,4×10 6 ind m −3 . La plus forte valeur est enregistrée au niveau du bassin M3, où les nauplii représentent 7,71 × 10 5 ind m −3 correspondant à une biomasse de l'ordre de 31,8 g m −3 . Par contre, le nombre des mâles et des femelles est faible avec 34 et 17 × 10 3 ind m −3 , respectivement. Les cystes d'Artemia prédominent (92,9% de l'abondance total), et ils sont repré...

Solar Salterns and Pollution: Valorization of Some Endemic Species as Sentinels in Ecotoxicology

“…The physicochemical properties of seawater change due to evaporation in the flow-through multi-pond system. Although the pH of seawater is slightly alkaline, owing to carbonate buffering systems, the pH of saline water in salterns is generally close to neutral in ponds with biota [ 3 , 8 , 9 , 10 , 11 , 12 ]. The pH of ponds in salterns can be regulated via the salinity, temperature, and amount of carbonate ions [ 2 ].…”

The Solar Saltern of Sfax: Diversity of Hyperhalophilic Microalgae Species as a Promising Naturel Source of Biomolecules

“…The Sfax solar saltern (Tunisia) is an artificial paralic ecosystem characterized by its floristic and faunal richness [7], as well as by its microalgae richness [8,9]. This biotope has been the site of several studies since 1998: (i) microalgae [10], (ii) ciliates [11] and (iii) zooplankton [12][13][14] especially the branchiopod crustacean Artemia salina [15,16]. The cultures of microalgae sampled from the Sfax solar saltern have been the subject of several studies [17][18][19][20].…”