Inland Saline Waters Research Articles

Disentangling responses of aquatic and terrestrial invertebrates to drying in saline streams and shallow lakes

In inland aquatic ecosystems, drying and salinity can co-occur as natural stressors, affecting aquatic invertebrate communities. Despite recent appreciation of the importance of temporary waterbodies for terrestrial invertebrates, knowledge about the effects of drying on dynamics of aquatic and terrestrial invertebrate communities is scarce, especially in saline ecosystems. This study analyzed structural and compositional responses of both communities to the coupled effects of drying and salinity in two streams and two shallow lakes in Spain, during three hydrological phases: wet, contraction, and dry. In the two studied saline streams, the contraction phase presented the highest aquatic and terrestrial abundance and richness, and the main compositional changes were mainly due, to an increase in aquatic lentic taxa (e.g., Coleoptera), and Araneae and Formicidae as terrestrial taxa. In shallow lakes, which presented highly variable salinity conditions, the highest abundance and diversity values were found at the wet phase for aquatic invertebrates and at the dry phase for terrestrial invertebrates. Compositional invertebrate community changes were due to a decrease in Rotifera and Anostraca (aquatic taxa) in the contraction phase for aquatic communities, and to an increase of Araneae, Coleoptera, and Formicidae (terrestrial taxa) at the dry phase for the terrestrial. Our study evidences the significant effect of drying on both aquatic and terrestrial invertebrates communities in natural inland saline waters and the need to integrate aquatic and terrestrial perspectives to study temporary inland waters.

Effect of sulfate on the osmoregulatory and physio-biochemical responses of GIFT (Oreochromis niloticus) juveniles reared in potassium-deficient medium saline waters.

The inland saline waters were continuously observed to have low potassium concentrations compared to their seawater counterpart of the same salinity. We hypothesize that the toxic effect of sulfate may manifest in low potassium saline (LPSW) waters compared to brackish water of the same salinity. Thus, LC50 trials were performed in GIFT (genetically improved farmed tilapia) fry (0.5 ± 0.02 g) to determine the acute sulfate toxicity in freshwater (FW, 0.5 g L-1), artificial seawater (ASW, 10 g L-1), and LPSW (10 g L-1). The median lethal concentrations (96h LC50) of sulfate ion in FW, LPSW, and ASW for the GIFT were 5.30 g L-1, 2.56 g L-1, and 2.98 g L-1, respectively. A second experiment was conducted for 21 days, exposing fish to a sub-lethal level of sulfate ion (SO42-) concentration (1000 mg L-1, one-fifth of FW LC50) with different types of waters (FW, freshwater, 0.5 g L-1; ASW, artificial seawater, 10 g L-1; LPSW, low potassium saline water, 10 g L-1) with and without sulfate inclusion to constitute the treatments as follows, (FW, FW + SO4, ASW, ASW + SO4, LPSW, LPSW + SO4). The effect of sulfate on GIFT reared in sulfate-rich potassium-deficient medium saline water was evaluated by focusing on the hematological adjustments, stress-induced oxidative damage, and osmoregulatory imbalances. The survival was not altered due to the sulfate concentration and K+ deficiency; however, there were significant changes in branchial NKA (Na+/K+-ATPase) activity and osmolality. The increase in NKA was highest in LPSW treatment, suggesting that internal ionic imbalance was triggered due to an interactive effect of sulfate and K+ deficiency. The cortisol levels showed a pronounced increase due to sulfate inclusion irrespective of K+ deficiency. The antioxidant enzymes, i.e., SOD (superoxide dismutase), catalase, GST (glutathione-S-transferase), and GPX (glutathione peroxidase), reflected a similar pattern of increment in the gills and liver of the LPSW + SO4 groups, suggesting a poor antioxidant status of the exposed group. The hepatic peroxidation status, i.e. TBARS (thiobarbituric acid reactive substances), and the peroxide values were enhanced due to both K+ deficiency and sulfate inclusion, suggesting a possible lipid peroxidation in the liver due to handling the excess sulfate anion concentration. The hematological parameters, including haemoglobin, total erythrocyte count, and hematocrit level, reduced significantly in the LPSW + SO4 group, indicating a reduced blood oxygen capacity due to the sulfate exposure and water potassium deficiency. The hepatic acetylcholine esterase activity was suppressed in all the treatments with sulfate inclusion, while the highest suppression was observed in the LPSW + SO4 group. Thus, it is concluded that sulfate-induced physiological imbalances manifest more in potassium-deficient water, indicating that environmental sulfate is more detrimental to inland saline water than freshwater or brackish water of the same salinity.

Regional and fine-scale local adaptation in salinity tolerance in Daphnia inhabiting contrasting clusters of inland saline waters.

Understanding the spatial scales at which organisms can adapt to strong natural and human-induced environmental gradients is important. Salinization is a key threat to biodiversity, ecosystem functioning and the provision of ecosystem services of freshwater systems. Clusters of naturally saline habitats represent ideal test cases to study the extent and scale of local adaptation to salinization. We studied local adaptation of the water flea Daphnia magna, a key component of pond food webs, to salinity in two contrasting landscapes-a dense cluster of sodic bomb crater ponds and a larger-scale cluster of soda pans. We show regional differentiation in salinity tolerance reflecting the higher salinity levels of soda pans versus bomb crater ponds. We found local adaptation to differences in salinity levels at the scale of tens of metres among bomb crater pond populations but not among geographically more distant soda pan populations. More saline bomb crater ponds showed an upward shift of the minimum salt tolerance observed across clones and a consequent gradual loss of less tolerant clones in a nested pattern. Our results show evolutionary adaptation to salinity gradients at different spatial scales, including fine-tuned local adaptation in neighbouring habitat patches in a natural landscape.

The effects of non-lethal heat-shock-induced cross-protection on survival and growth of Pacific whiteleg shrimp, Litopenaeus vannamei in response to ionic stress in inland saline waters

Non-lethal heat shock (NLHS) was used to enhance tolerance to other stressors in aquatic organisms and its effects are associated with the accumulation of Hsp 70. A study was conducted to determine the effect of NLHS on the cross-protection of L. vannamei against stress in K+-deficient inland saline water. To determine the NLHS based on mortality and gill heat shock protein 70 (Hsp70) abundance, L. vannamei juveniles (3.52 ± 0.23 g) were reared in inland water of 10 ppt salinity with 100% seawater equivalent (SWequ) K+ fortification. As one hour of heat shock at 36 °C resulted no mortality and a 3.5-fold increase in Hsp70 protein in gills when followed by 8 h recovery at 28 °C, the 36 °C was designated as NLHS. Subsequently, P. vannamei juveniles (4.64 ± 0.01 g) were exposed to 1 h NLHS in inland saline water containing 25%, 50% and 75% of SWequ K+ in triplicates following a recovery of 8 h, whereas the control group did not receive NLHS. The NLHS significantly increased Hsp70 protein in the gills and muscle. In addition, NHLS brought about higher catalase and superoxide dismutase activity in the gills and hepatopancreas, along with increased serum glucose levels. Increased Hsp70 protein abundance in muscle and gills remained elevated even after 12 h exposure to varying K+ levels, conferring cross-protection by NLHS against ionic stress caused by K+ depletion in inland saline waters. A 45-day growth study showed a significant increase in weight gain and survival (%) in NLHS groups compared to the control group, irrespective of the K+ fortification. This growth-promoting effect of NLHS was also evident in the group reared in the most K+ deficient inland saline water. This study shows that NLHS provides cross-protection through accumulation of Hsp70 protein and activation of antioxidant enzymes, in K+ deficient inland saline water, promoting shrimp growth and survival with atleast 50 aqueous K+ supplementation.

Ecosystems of Inland Saline Waters in the World of Change

Ecosystems of inland saline waters play a significant role in the biosphere and human life. Various articles of this Special Issue are devoted to a wide range of issues of their study and management. This introductory article gives a general overview of the types of inland waters on the planet, as well as the features of their ecosystems, reflected in 18 articles of this Special Issue. Attention is also paid to modern problems of conservation and integrated sustainable use of aquatic ecosystems in a changing climate and increasing anthropogenic pressure on water bodies.

Waterbird guilds predict environmental attributes of inland saline aquatic ecosystems on multi-spatial scales

Inland saline waters in Central Asia constitute an important part of steppe ecosystems, providing considerable ecological functions and ecosystem services. Here we aim to present a multi-spatial scale analysis of nutrient cycling and transport waterbird guilds, and the environmental attributes of saline-soda aquatic ecosystems in Kazakhstan. The density, biomass, and diversity of waterbird guilds was determined in the case of three nutrient cycling and transport guilds: a) net-importer (IM), b) importer-exporter (IMEX), c) net-exporter (EX), according to the Boros's guild classification method, and for several traditional feeding guilds: carnivorous, herbivorous, invertebrate eater, omnivorous and piscivorous.Our results revealed that waterbird guilds, as predictors represented by the complete waterbird community, are in close relationship with several (N = 12) environmental attributes of inland saline waters through complex trophic linkages of waterbird populations on multi-spatial scales. The density and the biomass of the EX and IMEX guilds are strongly and positively correlated (i) with the productivity metrics of habitats (e.g., CHL, GPP), indicating their trophic position, and (ii) with water depth. We found significant correlations among guild density, biomass, diversity and environmental attributes on multi-spatial scales for IMEX and EX. Our results revealed that IMEX predicts the surrounding environment of aquatic habitats, whereas EX species are substantial environmental predictors of aquatic ecosystems. However, the diversity metric had valid models only with EX. The herbivorous and omnivorous guilds, that feed chiefly on plant materials consist mainly of IMEX and EX duck species, which were positively related to grassland coverage and the shoreline development index.As a methodological result, here we present a novel approach, the guild transport index, which has more robust relationships with environmental attributes than individual guilds, thus it provides a complex evaluation of the nutrient cycling by birds between aquatic and terrestrial environments on multi-spatial scales.

Where the Little Ones Play the Main Role-Picophytoplankton Predominance in the Soda and Hypersaline Lakes of the Carpathian Basin.

The extreme environmental conditions of the diverse saline inland waters (soda lakes and pans, hypersaline lakes and ponds) of the Carpathian Basin are an advantage for picophytoplankton. The abundance of picophytoplankton in these waters can be up to several orders of magnitude higher than that in freshwater shallow lakes, but differences are also found within different saline water types: higher picophytoplankton abundances were observed in hypersaline lakes compared to humic soda lakes, and their highest numbers were detected in turbid soda lakes. Moreover, their contribution to phytoplankton biomass is higher than that in shallow freshwater lakes with similar trophic states. Based on long-term data, their ratio within the phytoplankton increased with turbidity in the case of turbid soda lakes, while, in hypersaline lakes, their proportion increased with salinity. Picocyanobacteria were only detected with high abundance (>106–107 cells/mL) in turbid soda lakes, while picoeukaryotes occurred in high numbers in both turbid and hypersaline lakes. Despite the extreme conditions of the lakes, the diversity of picophytoplankton is remarkable, with the dominance of non-marine Synechococcus/Cyanobium, Choricystis, Chloroparva and uncultured trebouxiophycean green algae in the soda lakes, and marine Synechococcus and Picochlorum in the hypersaline lakes.

Diversity of Brachionus plicatilis species complex (Rotifera) in inland saline waters from China: Presence of a new mitochondrial clade on the Tibetan Plateau

The biogeography and molecular phylogeny of invertebrate zooplankton populations from inland saline waters remains under-explored in the Eastern Palearctic, especially the Qinghai-Tibetan Plateau. Here, we surveyed the diversity of the Brachionus plicatilis Müller, 1786 species complex from inland saline waters across China. We compared morphometrics with DNA taxonomy (using two genetic markers: the mitochondrial cytochrome c oxidase subunit I (COI) gene and the nuclear internal transcribed spacer (ITS-1)). Our phylogenies based on the sequences of ITS-1 recognized two distinct clades (i.e. two species: B. plicatilis sensu stricto (s.s.) and B. asplanchnoidis) in China. We detected two mitochondrial clades within B. plicatilis s.s and one within B. asplanchnoidis across China, consistent with the three morphogroups present. One of these three clades was novel and restricted to the Qinghai-Tibetan Plateau, where it exhibited evidence of recent expansion across the region. The new mitochondrial clade fell within B. plicatilis s.s. but was sister to all other mitochondrial sequences of that species, suggesting a period of isolation from other populations. Moreover, significant morphological differences were identified: B. plicatilis s.s. from the Qinghai-Tibetan Plateau had a larger lorica length and width than did members of this species from lowland China. Our data demonstrate the successful adaptation of this species complex to the harsh environment of the Qinghai-Tibetan Plateau.

Zooplankton Community Structure in Shallow Saline Steppe Inland Waters

Several shallow saline waters can be found in Central Asia in arid steppe climate, but our knowledge of their zooplankton community has been so far rather limited. The aim of our research was to provide data on the steppe zooplankton community in a large-scale regional study. Therefore, a baseline survey was carried out in 23 shallow inland waters of different salinity in Northern Kazakhstan. We measured the quantity and identified the taxonomic composition of zooplankton in the spring period and examined changes in community structure in correlation with salinity. Lesser salt concentration of the hyposaline–mesosaline waters was indicated by the presence of halophilic rotifer species: Brachionus asplanchnoides, Br. dimidiatus, Br. plicatilis. Mesosaline and hypersaline waters were indicated by the presence of halobiont crustaceans: Moina salina, Arctodiaptomus salinus, Cletocamptus retrogressus. Very high concentration of salt was indicated by presence of Artemia alone which is the only group, that can tolerate and adapt to this extreme environment. In the hypersaline waterbodies at over 79 gL−1 high TDS conditions a very simple tropical structure was found. Artemia playing monopolistic ecological function in the zooplankton community. We identified three characteristic groups of shallow inland saline waters based on their zooplankton composition.

Growth, biochemical indices and carcass quality of red tilapia reared in zero water discharge based biofloc system in various salinities using inland saline ground water

Biofloc based aquaculture is important in waste recycling in intensive aquaculture and is a promising avenue for inland saline aquaculture. In the present study, growth, biochemical and carcass quality of red tilapia reared in inland saline waters of different salinities based on biofloc technology was estimated during 90 days culture period. Fifteen experimental tanks (500 L each) were filled with inland saline ground water to represent 5 biofloc treatments with variable salinities such as T1 (5 ppt), T2 (10 ppt), T3 (15 ppt), T4 (20 ppt) and control (0 ppt) in triplicates. Red tilapia fry with average body weight of 13.78 ± 0.62 g were stocked at the rate of 150 no.m ‐3 in each biofloc unit. The units maintained at higher salinity (20 ppt) obtained significantly better (P < 0.05) growth performances in terms of percentage weight gain (329.89 ± 13.41), specific growth rate (1.65 ± 0.05), protein efficiency ratio (1.18 ± 0.07) and feed conversion ratio (0.93 ± 0.06). Biochemical properties such as serum glucose (118.49 ± 3.73 mg dL−1), serum total protein (4.23 ± 0.04 mg dL−1), total serum albumin (2.08 ± 0.03 mg dL−1), and total serum globulin (2.16 ± 0.04 mg dL−1) contents were the highest in T4 (20 ppt), whereas activities of enzymes, superoxide dismutase and catalase were the highest in control (0 ppt). Treatment T4 (20 ppt) had shown the highest survival rate (95.56 ± 1.28), carcass quality like firmness (121.45 ± 1.91), and whiteness (49.52 ± 0.79) and in addition, overall sensory attributes were also the highest in T4 (20 ppt). Consequently, the findings of the current investigation have shown that growth efficiency, survival, biochemical indices and carcass quality of red tilapia had improved when reared in higher salinity using inland saline groundwater.

Cuticle Hydrocarbons Show Plastic Variation under Desiccation in Saline Aquatic Beetles.

Simple SummaryDesiccation resistance and physiological plasticity are key traits for species persistence in the context of aridification under global change. One of the main mechanisms of desiccation resistance in insects is the control of cuticular transpiration through changes in the quantity and composition of epicuticular hydrocarbons (CHCs), which have been well studied in terrestrial insects. Our study provides novel information regarding the capacity to cope with desiccation stress through plastic changes in the composition of cuticle hydrocarbons in aquatic insects from saline intermittent streams. We demonstrate that the plasticity of CHCs is an effective mechanism to regulate water loss rate under desiccation stress in the most saline-tolerant species studied. These traits, so far largely unexplored in aquatic insects, are relevant to understanding different biochemical adaptations to deal with drought stress in inland saline waters in an evolutionary and ecological context.In the context of aridification in Mediterranean regions, desiccation resistance and physiological plasticity will be key traits for the persistence of aquatic insects exposed to increasing desiccation stress. Control of cuticular transpiration through changes in the quantity and composition of epicuticular hydrocarbons (CHCs) is one of the main mechanisms of desiccation resistance in insects, but it remains largely unexplored in aquatic ones. We studied acclimation responses to desiccation in adults of two endemic water beetles from distant lineages living in Mediterranean intermittent saline streams: Enochrus jesusarribasi (Hydrophilidae) and Nebrioporus baeticus (Dytiscidae). Cuticular water loss and CHC composition were measured in specimens exposed to a prior non-lethal desiccation stress, allowed to recover and exposed to a subsequent desiccation treatment. E. jesusarribasi showed a beneficial acclimation response to desiccation: pre-desiccated individuals reduced cuticular water loss rate in a subsequent exposure by increasing the relative abundance of cuticular methyl-branched compounds, longer chain alkanes and branched alkanes. In contrast, N. baeticus lacked acclimation capacity for controlling water loss and therefore may have a lower physiological capacity to cope with increasing aridity. These results are relevant to understanding biochemical adaptations to drought stress in inland waters in an evolutionary and ecological context.

Extreme weather drives spatial and temporal variation in water bug (Heteroptera: Gerromorpha, Nepomorpha) assemblages in soda pans in Hungary

ABSTRACT Soda pans in Central Europe are inland saline waters of nonmarine origin that represent dynamically changing environments with unique species and communities. Our aim was to explore the spatial and temporal variation in water bug assemblages among soda pans at 3 temporal scales (years, seasons, and months). Data on 9005 individuals belonging to 18 species collected in 3 seasons per year for 4 years in 5 soda pans demonstrated large interannual and seasonal fluctuations of water bugs. Two water boatman species (Paracorixa concinna, Sigara lateralis) were dominant, and species composition varied little among soda pans, seasons, or years. Species richness and abundance were influenced by interactions among soda pans, year, and season and showed cyclic changes in dry years and serial changes in wet years. Richness and abundance were highest in 2000 when water levels were high in spring and early summer. Richness was also high but abundance was lowest in 2010, a year with extremely high precipitation after a dry year. Richness and abundance peaks (individual numbers up to 2100 m−2) occurred in late summer, suggesting that water bugs are important in the trophic network of soda pans. Our results suggest that weather-driven extreme fluctuations in soda pans determine the spatial and temporal variation of water bug assemblages, with cycles of local extinction and recolonization maintained by good dispersal ability.

Multiple Euryhaline Lineages of Centrohelids (Haptista: Centroplasthelida) in Inland Saline Waters Revealed with Metabarcoding.

The diversity of centrohelids in inland saline waters was studied with metabarcoding for the first time. The fragment of V6-V7 regions of 18S rDNA was sequenced with newly designed primers. Obtained OTUs were identified with molecular phylogenetic analysis and comparison of the signatures in 39es9 hairpin of V7. The obtained data included some OTUs, which could be attributed to four described species, but the majority belonged to previously established or novel environmental clades. Along with some presumably marine/brackish clades and freshwater/low salinity (0-2 ppt) clades, seven presumable species demonstrating broad (from 1-2 up to 78 ppt) salinity tolerance were detected. A number of OTUs belonged to Raphidocystis contractilis, which is known from three independent findings in brackish habitats only. Thus, it was assumed that this species is stenohaline and specifically adapted to salinity 5-15 ppt. The high level of salinity tolerance was suggested for centrohelids before based on morphology, which was used to justify their cosmopolitan distribution. Later these views were criticized based on environmental sequencing, but the results of the current survey indicate, that at least some species are present at salinities from almost freshwater (1-2 ppt) to twice oceanic (78 ppt) and are presumably capable of overcoming oceanic salinity barriers for their distribution.

Effect of low salinity on the growth and survival of juvenile pacific white shrimp, Penaeus vannamei: A revival

The euryhaline white shrimp Penaeus vannamei lives in both coastal and oceanic areas and is capable of surviving over a large range of salinities. There is an ambiguity on its osmoregulation pattern and variations in its tolerance to low salinity waters. In order to determine the effects of salinity on growth, survival, osmotic regulation and ionic composition (Na+, K+, Ca++ and Mg++), the juveniles of P. vannamei were divided into five treatments (1, 5, 7, 15 and 25 ppt) in triplicates for conducting the experiment. The experiment was carried out over a period of 3 weeks with two sampling time points (8th and 21st day). No significant differences (P > 0.05) were found in feed conversion rate, survival percentage, body weight gain percentage and specific growth rate. The isosmotic point estimated was 671.3 mOsm/kg (21.1 ppt) which is the lowest value obtained for the genus Penaeus so far. The hemolymph osmolality was regulated within a narrow range for wide variations in salinity. Changes in hemolymph Na+ and Mg++ concentrations paralleled those of hemolymph osmolality; values were around significantly higher at 15 ppt than other treatments. Whereas, K+ and Ca++ were present at higher concentrations than Mg++ and lower than Na+ but didn't show any trend with the hemolymph osmolality. It suggested that total calcium levels are maintained regardless of salinity and may not bear a connection with osmoregulatory mechanisms. Among the four ions determined, the sodium was found at highest concentration in hemolymph followed by calcium, potassium and magnesium. Our findings suggest that low salinity does not seem to affect osmotic regulation to the extent so that growth and survival rate will be affected in P. vannamei. If the acclimation process is followed properly, the species has excellent potential in inland saline waters at salinity as low as 1 ppt.

Role of cuticle hydrocarbons composition in the salinity tolerance of aquatic beetles

Salinity tolerance has enabled the colonization of inland saline waters and promoted species diversification in some lineages of aquatic insects. However, the mechanisms behind this tolerance, particularly the role of cuticle hydrocarbons (CHCs), are not well-known. We characterized the CHC profile of eight species of two water beetle genera (Nebrioporus, Adephaga: Dytiscidae and Enochrus, Polyphaga: Hydrophilidae), which span the fresh-hypersaline gradient, to: i) determine the interspecific variation of CHC composition in relation to species’ salinity tolerance; ii) explore plastic adjustments in CHC profiles in response to salinity changes at the intraspecific level in saline-tolerant species. CHC profiles were highly species-specific, more complex and diverse in composition, and characterized by longer-chain-length compounds in the species with higher salinity tolerance within each genus. Higher salinity tolerance in the Enochrus species was also associated with an increase in the relative abundance of branched alkanes, and with a lower proportion of n-alkanes and unsaturated compounds. These CHC characteristics are related with improved waterproofing capacity and suggest that reducing cuticle permeability was one of the key mechanisms to adapt to saline waters. Similar CHC composition patterns were found at the intraspecific level between populations from lower and higher salinity sites within saline-tolerant species of each genus. These saline species also displayed an extraordinary ability to adjust CHC profiles to changing salinity conditions in the laboratory in a relatively short time, which reflects great plasticity and a high potential to deal with daily and seasonal environmental fluctuations in the highly dynamic saline habitats.

Halotolerant Copepoda in South American inland saline waters

Abstract The zooplankton in South American saline waters is mainly dominated by copepods at salinities lower than 90 g/l, whereas at salinities above 90 g/l Artemia sp. is totally dominant. The aim of the present study is to analyse the salinity range of halophilic copepods on the basis of a literature review for South American saline inland waters. The calanoid Boeckella poopoensis Marsh, 1906, is widespread on the South American Altiplano and southern Argentinian plains, and in southern Patagonian shallow ponds. In the upper part of the salinity range, 20-90 g/l, B. poopoensis is the only copepod in the zooplankton of southern Patagonian and Altiplano shallow lakes. In the salinity range 5-20 g/l B. poopoensis may co-exist with B. palustris (Harding, 1955), two cyclopoids and an harpacticoid, and at salinities lower than 5 g/l it may co-exist with an even wider range of copepod species. Ecological and biogeographical aspects are also discussed.

Nitzschia austriaca Hustedt: a characteristic diatom of Hungarian inland saline waters including a morphological comparison with the type material

A detailed scanning electron microscopic investigation was carried out to clarify the taxonomic status of a small sigmoid Nitzschia species, a potential indicator of Central European soda waters. We found this taxon to be one of the dominant epiphytic diatoms collected from sodic bomb crater ponds at Apaj (Hungary). The large population allowed for a morphometric comparison based on frustule ultrastructure with the type material of the most similar species, Nitzschia austriaca Hustedt that was originally described from a soda pan in the region. The results clearly demonstrated an overlap between the Apaj population and the type material of N. austriaca (based on NMDS analysis), therefore we argue that they represent the same taxon. An emended diagnosis of N. austriaca is given. Total suspended solids and total phosphorous proved to be the most important factors predicting the occurrence of the species, with possible interactive effects of conductivity and pH. We then expanded the distribution of the species by revisiting data originating from previous large-scale surveys targeting sodic habitats in Hungary. On the basis of our results, N. austriaca is a characteristic species for Central European soda waters, including the protected astatic soda pans, indicating their typical chemical and physical characteristics.

Aquatic insects in a multistress environment: cross-tolerance to salinity and desiccation.

Exposing organisms to a particular stressor may enhance tolerance to a subsequent stress, when protective mechanisms against the two stressors are shared. Such cross-tolerance is a common adaptive response in dynamic multivariate environments and often indicates potential co-evolution of stress traits. Many aquatic insects in inland saline waters from Mediterranean-climate regions are sequentially challenged with salinity and desiccation stress. Thus, cross-tolerance to these physiologically similar stressors could have been positively selected in insects of these regions. We used adults of the saline water beetles Enochrus jesusarribasi (Hydrophilidae) and Nebrioporus baeticus (Dytiscidae) to test cross-tolerance responses to desiccation and salinity. In independent laboratory experiments, we evaluated the effects of (i) salinity stress on the subsequent resistance to desiccation and (ii) desiccation stress (rapid and slow dehydration) on the subsequent tolerance to salinity. Survival, water loss and haemolymph osmolality were measured. Exposure to stressful salinity improved water control under subsequent desiccation stress in both species, with a clear cross-tolerance (enhanced performance) in N. baeticus In contrast, general negative effects on performance were found under the inverse stress sequence. The rapid and slow dehydration produced different water loss and haemolymph osmolality dynamics that were reflected in different survival patterns. Our finding of cross-tolerance to salinity and desiccation in ecologically similar species from distant lineages, together with parallel responses between salinity and thermal stress previously found in several aquatic taxa, highlights the central role of adaption to salinity and co-occurring stressors in arid inland waters, having important implications for the species' persistence under climate change.

The Occurrence of Marine Alga Enteromorpha Intestinalis in Water Courses from Salt Area Meledic Plateau, Vrancei Subcarpathians (Romania)

AbstractThree new sites of Enteromorpha intestinalis have been found in the drainage basin of the Slănic River located in the Subcarpathians region, salt Meledic Plateau. E. intestinalis is a cosmopolitan macro green alga species with tubular thali that is primarily found in the coastal zone, including the Romanian Black Sea coast. Due to its salt tolerance this alga it was found in some inland waters, both fresh and saline waters courses and limnic waters that are often positively correlated with cultural eutrophication. These new reported localities of E. intestinalis in inland waters from this saline region contribute new and essential information about the distribution of this originally marine species on the inland area of Romania.

Picocystis salinarum (Chlorophyta) in saline lakes and hot springs of East Africa

Krienitz L., Bock C., Kotut K. And Luo W. 2012. Picocystis salinarum (Chlorophyta) in saline lakes and hot springs of East Africa. Phycologia 51: 22–32. DOI: 10.2216/11-28.1The occurrence of Picocystis salinarum in saline inland waters of East Africa was investigated using a polyphasic approach of small-subunit (SSU) rDNA phylogeny and light microscope observations. Recent studies have found that Picocystis occasionally replaces the dominant cyanobacterium (Arthrospira fusiformis), which is the main food resource of Lesser Flamingos, in soda lakes of Bogoria and Nakuru. This article discusses the consequences of a high abundance (maximum cell numbers of > 3 billion cells l−1) of Picocystis on food chains of African saline waters. During the study, we found a new morphotype of Picocystis characterized by larger cell sizes and absence of lobes in hot springs near Lake Magadi. SSU rRNA genes of Picocystis strains and uncultured field clones collected from Lake Nakuru were subjected to phylogenetic analyses together with other picoplankton from field and culture samples from saline, marine or freshwater. Picocystis salinarum from saline inland waters represents a link between marine and freshwater habitats from both an ecological and a phylogenetic point of view and is therefore of great interest.