Hyposaline Waters Research Articles

Application of capacitive deionizing membrane distillation (CDIMD) system for seawater desalination: Emphasizing on the impacts of operating parameters

Although membrane distillation (MD) is highly regarded as a promising technique for seawater desalination, membrane scaling induced by the accumulation of crystals is the crucial obstacle for real application of MD. Capacitive deionization (CDI), another novel desalination technology, is mainly applied in the desalination of hyposaline water, and its desalination efficiency is inferior to MD. Even so, the electro-absorption desalination mechanism of CDI is a novel enlightenment for alleviating MD scaling. Hence, we developed a new-type desalination technique by integrating CDI with traditional MD system to retard MD scaling, namely capacitive deionizing membrane distillation (CDIMD) technique. In the CDIMD system, the anions and cations were respectively separated by the activated carbon fiber felt (ACFF) electrodes and lab-made electrically conductive membranes (CNTs-PTFE), accordingly alleviating the combination of salt ions and the subsequent membrane scaling development. The influences of crucial operation parameters of CDIMD on the desalination efficiency were deeply researched. The results revealed that feed temperature of around 65 °C, feed flow velocity of 15.72 mm/s, operating mode of forward-CDIMD, input voltage of 1.2–1.6 v, CNTs thickness of 40–60 μm, and a short time-set of ion-adsorption/desorption phases (9/1 min and 17/3 min) might contribute to the CDIMD desalination.

Salinity Affects Wound Healing in Wild Common Bottlenose Dolphins (Tursiops truncatus)

Dolphins are often individually identified by unique naturally-acquired markings. Identification becomes difficult when markings heal, or new scars appear. As salt accelerates wound healing in many organisms, the diminishment of scars on common bottlenose dolphins (Tursiops truncatus) residing in varying natural salinities was determined. South Texas contains the only hypersaline lagoon in the USA, located adjacent to hyposaline waters, with genetically distinct populations of dolphins in the two environments. Photographs of dolphin dorsal fins were collected, and scar stability over time was determined and compared by measuring changes in the relative lengths and surfaces of scars. All scars on dolphins in the hypersaline lagoon completely diminished between three to six years, while scars on dolphins in the hyposaline bay ranged in the amount of fading between three to six years. Data from this case study indicate that high salinity may increase the healing speed of wounds on common bottlenose dolphins compared to low salinity, although a larger sample size is needed for robust statistical comparison. Scar diminishment is an important consideration in determining the temporal reliability of photo identification. KEYWORDS: Bottlenose dolphin; Corpus Christi Bay; healing; hypersaline; Laguna Madre; photo-identification; salinity; scar

Hyposaline to hypoxic foraminiferal facies and stratigraphy of Middle Jurassic to basal Cretaceous deposits of the Trøndelag Platform, mid-Norwegian shelf

The study is based on sample material and log data from the commercial well 6610/7-1 drilled on the Trøndelag Platform. The Melke and Spekk formations of the well contain a Bajocian to Ryazanian foraminiferal succession, here used for stratigraphic zonation and assessment of environmental conditions. Seven interval zones are established, with age estimates primarily based on foraminiferal stratigraphy using regional ranges of taxa. The foraminiferal assemblages are strongly dominated by agglutinated taxa and show low species diversities reflecting the effects of restricting water mass properties. Through most of the Melke Formation, morphogroup analysis of foraminifera reveals nearly equal amount of sediment-dwelling and surficial components suggesting that the bottom waters were sufficiently oxygenated for an infaunal mode of life. Through this formation, hyposaline waters low in carbonate are regarded the dominant factors controlling the development of foraminiferal assemblages. The organic-rich shales of the Spekk Formation with high gamma activity are typified by very low to extremely low species diversities and high dominance of the surface-dwelling morphogroup mainly composed of small-sized species of Trochammina, suggesting hypoxia as the main restricting factor. Here, CO2 release from organic matter degradation led to seawater acidification contributing to creation of inhospitable conditions for calcareous foraminifera. Restricted basinal conditions with stagnant bottom waters and high organic productivity are assumed crucial for this development. Comparison between foraminiferal assemblages of the Trøndelag Platform and the paleo-Arctic seas reveals close similarities illustrating that the mid-Norwegian shelf belonged to the Boreal Realm in accordance with a direct marine communication.

Palaeoecologic and Palaeoclimatic Inferences from Calcareous Nannofossils in Western Lobe Offshore, Niger Delta

In support of the ongoing temporal palaeoenvironment and palaeoclimatic reconstructions of the Neogene sediments, this study attempts to detail the paleo-proxies recovered from DEL-1 Well, western offshore Niger Delta. The standard smear slide method enabled the recovery of well-preserved calcareous nannofossils that depict early to mid–Miocene (NN4–NN5) sediments. The up-hole relationships between the nannofossil accumulation rate (NAR), the relative abundance of Discoaster and coccolith size of Reticulofenestra show step by step collapse of sea surface stability from early to middle Miocene. The lower horizons (8000–9460 ft) exhibit a low NAR, relatively high Discoaster abundance and relatively large Reticulofenestra size to suggest a deep thermocline and nutricline that characterise oligotrophic conditions in less warm-water induced climate. Conversely, upper horizons (5225–6550 ft) exhibit a high NAR, relatively low Discoaster abundance and relatively small Reticulofenestra size to suggest a shallow thermocline and nutricline that characterise eutrophic conditions in warm-water induced climate. The relative abundance of Helicosphaera carteri within the mid-NN5 suggests mesotrophic conditions within a stressed environment, with the possible occurrence of carbonate crash events. The combined parameters indicate gradual eutrophication and collapse of sea surface stability favouring nutrients and influx of terrestrial sediments in the ocean water as it progressed from early to middle Miocene. The abundance of the palaeo-proxies assemblages suggests hyposaline waters in a neritic environment that prevailed during the warm climatic condition.

Novel use of nanofiltered hyposaline water to control sea lice (Lepeophtheirus salmonis and Caligus elongatus) and amoebic gill disease, on a commercial Atlantic salmon (Salmo salar) farm

Infestations by the salmon louse (Lepeophtheirus salmonis) and amoebic gill disease (AGD) are currently significant disease concerns facing the Atlantic salmon aquaculture industry in Ireland. Increasing seawater temperatures, and the move away from chemotherapeutants has prompted a new approach to researching areas of host-parasite life histories and using the physiology and behaviour of the parasites to develop novel control methods. Freshwater, with a low ionic concentration can be used to control sea lice and AGD but this may not always be available. Alternative treatments with hydrogen peroxide can prove toxic at the higher summer water temperatures experienced at this latitude. The aim of this study was to determine the efficacy of using nano-filtered hyposaline water as a non-medicinal method to reduce sea lice (L. salmonis and Caligus elongatus) infestation levels and amoebic gill disease under commercial conditions on an Atlantic salmon farm. To achieve this salmon were bathed in a tarpaulin filled with 5 ppt hyposaline water for 4.5 h and a regime of prophylactic bath treatments put in place to follow the production cycle. The nano-filtration unit consistently produced low saline water and resulted in a significant reduction of sea lice levels and AGD following routine 4.5 h baths. A 4.5 h bioassay of detached salmon lice confirmed both hyposaline and freshwater were equally effective against L. salmonis in the absence of the host.

Evidence for physiological niche expansion of an intertidal flatworm: evolutionary rescue in the wild

Microevolution may enable populations to adapt physiologically to rapid climate change. Where it exists, historical data could provide a rare opportunity to document such adaptation. The intertidal flatwormProcerodes littoralisexperiences large changes in salinity throughout the tidal cycle. We investigated whether regeneration performance ofP. littoralishas changed over the last century. We repeated identical experiments to those published in 1914 on the same species and from the same location. In the modern experiment, when tested across a range of different salinities (S = 3, 6, 28, 44 and 53),P. littoraliscould regenerate at lower salinities (S = 3) than reported previously. Also in the modern study, no significant optimum salinity could be identified, whereas in 1914 the optimum salinity (S = 28.5) was clear. The possibility of differences resulting from acclimation or oxygen availability instead of adaptation was investigated and discounted. It would appear that individuals from this population have extended their tolerance performance range further into hyposaline waters in the intervening 104 yr since the previous study. Local climate change is suggested to be the microevolution driver, as mean daily precipitation has increased and the number of days per year with no/trace precipitation has decreased in Plymouth, UK. Climate change is often considered a global phenomenon, but it drives local regime shifts. Here, we suggest an evolutionary shift attributable to a century-long local change in precipitation.

Metabolic performance and thermal and salinity tolerance of the coral Platygyra carnosa in Hong Kong waters

Stress-tolerant coral species, such as Platygyra spp., are considered to be well adapted to survive in marginal reefs, but their physiological response to short term exposure to abnormally high temperature and lowered salinity remains poorly understood. Using non-invasive techniques to quantitatively assess the health of Platygyra carnosa (e.g. respiration, photosynthesis, biocalcification and whiteness), we identified the plasticity of its energetics and physiological limits. Although these indicators suggest that it can survive to increasing temperature (25–32 °C), its overall energetics were seriously diminished at temperatures >30 °C. In contrast, it was well adapted to hyposaline waters (31–21 psu) but with reduced biocalcification, indicating short term adaptation for expected future changes in salinity driven by increased amounts and intensities of precipitation. Our findings provide useful insights to the effect of these climate drivers on P. carnosa metabolism and thus better forecast changes in their health status under future climate change scenarios.

Physiological trade-offs, acid-base balance and ion-osmoregulatory plasticity in European sea bass (Dicentrarchus labrax) juveniles under complex scenarios of salinity variation, ocean acidification and high ammonia challenge

In this era of global climate change, ocean acidification is becoming a serious threat to the marine ecosystem. Despite this, it remains almost unknown how fish will respond to the co-occurrence of ocean acidification with other conventional environmental perturbations typically salinity fluctuation and high ammonia threat. Therefore, the present work evaluated the interactive effects of elevated pCO2, salinity reduction and high environmental ammonia (HEA) on the ecophysiological performance of European sea bass (Dicentrarchus labrax). Fish were progressively acclimated to seawater (32 ppt), to brackish water (10 ppt) and to hyposaline water (2.5 ppt). Following acclimation to different salinities for at least two weeks, fish were exposed to CO2-induced water acidification representing present-day (control pCO2, 400 μatm, LoCO2) and future (high pCO2, 1000 μatm, HiCO2) sea-surface CO2 level for 3, 7 and 21 days. At the end of each exposure period, fish were challenged with HEA for 6 h (1.18 mM representing 50% of 96 h LC50). Results show that, in response to the individual HiCO2 exposure, fish within each salinity compensated for blood acidosis. Fish subjected to HiCO2 were able to maintain ammonia excretion rate (Jamm) within control levels, suggesting that HiCO2 exposure alone had no impact on Jamm at any of the salinities. For 32 and 10 ppt fish, up-regulated expression of Na+/K+-ATPase was evident in all exposure groups (HEA, HiCO2 and HEA/HiCO2 co-exposed), whereas Na+/K+/2Cl− co-transporter was up-regulated mainly in HiCO2 group. Plasma glucose and lactate content were augmented in all exposure conditions for all salinity regimes. During HEA and HEA/HiCO2, Jamm was inhibited at different time points for all salinities, which resulted in a significant build-up of ammonia in plasma and muscle. Branchial expressions of Rhesus glycoproteins (Rhcg isoforms and Rhbg) were upregulated in response to HiCO2 as well as HEA at 10 ppt, with a more moderate response in 32 ppt groups. Overall, our findings denote that the adverse effect of single exposures of ocean acidification or HEA is exacerbated when present together, and suggests that fish are more vulnerable to these environmental threats at low salinities.

Survival time of juvenile pen shell Atrina pectinata (Bivalvia: Pinnidae) in hyposaline water

Survival time of juvenile pen shell Atrina pectinata (shell length ≈ 34 mm) exposed to hyposaline water without sediments was investigated in laboratory experiments. The bivalves were individually maintained in rearing cups in which salinity was decreased either gradually (over 1–11 h to 12 salinities ranging from 0 to ca. 34 ppt) or rapidly (directly to 21 salinities) at 12 and 24 °C. When the environmental salinity was gradually decreased, survival time differed markedly between the bivalves exposed to: salinities ≤ 18.6 ppt (survival time < 20 h in general) vs. ≥ 21.1 ppt (> 83 h) at 24 °C; and between salinities ≤ 15.1 ppt (< 34 h) vs. ≥ 17.2 ppt (> 83 h) at 12 °C. When the environmental salinity was rapidly decreased, survival time, again, differed markedly between the bivalves exposed to: salinities ≤ 15.9 ppt (< 20 h in general) vs. ≥ 17.7 ppt (> 140 h) at 24 °C; and salinities ≤ 21.3 ppt (< 38 h in general) vs. ≥ 22.3 ppt (> 140 h) at 12 °C. Such sharp decreases in survival time due to reduced salinity led to the selected, statistical models that assume either a sharp exponential increase or stepwise hike in hazard (instantaneous mortality rate) according to salinity reduction. These data and models indicate that juvenile A. pectinata should not be kept at salinities < 21 ppt for periods > 1 day in environments without sediments.

Reciprocal transplants support a plasticity-first scenario during colonisation of a large hyposaline basin by a marine macro alga

BackgroundEstablishing populations in ecologically marginal habitats may require substantial phenotypic changes that come about through phenotypic plasticity, local adaptation, or both. West-Eberhard’s “plasticity-first” model suggests that plasticity allows for rapid colonisation of a new environment, followed by directional selection that develops local adaptation. Two predictions from this model are that (i) individuals of the original population have high enough plasticity to survive and reproduce in the marginal environment, and (ii) individuals of the marginal population show evidence of local adaptation. Individuals of the macroalga Fucus vesiculosus from the North Sea colonised the hyposaline (≥2–3‰) Baltic Sea less than 8000 years ago. The colonisation involved a switch from fully sexual to facultative asexual recruitment with release of adventitious branches that grow rhizoids and attach to the substratum. To test the predictions from the plasticity-first model we reciprocally transplanted F. vesiculosus from the original population (ambient salinity 24‰) and from the marginal population inside the Baltic Sea (ambient salinity 4‰). We also transplanted individuals of the Baltic endemic sister species F. radicans from 4 to 24‰. We assessed the degree of plasticity and local adaptation in growth and reproductive traits after 6 months by comparing the performance of individuals in 4 and 24‰.ResultsBranches of all individuals survived the 6 months period in both salinities, but grew better in their native salinity. Baltic Sea individuals more frequently developed asexual traits while North Sea individuals initiated formation of receptacles for sexual reproduction.ConclusionsMarine individuals of F. vesiculosus are highly plastic with respect to salinity and North Sea populations can survive the extreme hyposaline conditions of the Baltic Sea without selective mortality. Plasticity alone would thus allow for an initial establishment of this species inside the postglacial Baltic Sea at salinities where reproduction remains functional. Since establishment, the Baltic Sea populations have evolved adaptations to extreme hyposaline waters and have in addition evolved asexual recruitment that, however, tends to impede local adaptation. Overall, our results support the “plasticity-first” model for the initial colonisation of the Baltic Sea by Fucus vesiculosus.

Holocene paleoenvironmental reconstruction of Laguna Babícora, Chihuahua, Northern Mexico, based on Ostracode Ecology and Shell Chemistry

Fossil ostracodes from the Las Vacas trench measured in Laguna Babícora, Chihuahua, Mexico were analyzed taphonomically, and the shells of Limnocythere bradburyi were tested for trace-elements. Chronological control of the sediments was established using two calibrated 14C ages placing plant material at 9250 and 990 years B.P. Ostracode association is represented by Candona caudata, Eucandona patzcuaro, Cypridopsis vidua, Limnocythere platyforma and Limnocythere bradburyi. Population structure and taphonomy indicate a biocenosis living in a low energy lake, fluctuating from fresh to hyposaline water. Ostracode abundances in the studied interval ranged from 698 to 2 valves/g of sediment. Water salinity was established between 100 – 5000 ppm. Shell Mg/Ca molar ratios were used to interpret changes in lake temperature, with calculated temperatures ranging from 11.9 °C to 7.3 °C, revealing a low-temperature trend during the early to late Holocene. Our data contributes to the completion of the paleoenvironmental scenario for the Early to Mid-Holocene based on evidence that is consistent with other paleoclimatic reconstructions from the Babícora area.

Nutritional Status as the Key Modulator of Antioxidant Responses Induced by High Environmental Ammonia and Salinity Stress in European Sea Bass (Dicentrarchus labrax).

Salinity fluctuation is one of the main factors affecting the overall fitness of marine fish. In addition, water borne ammonia may occur simultaneously with salinity stress. Additionally, under such stressful circumstances, fish may encounter food deprivation. The physiological and ion-osmo regulatory adaptive capacities to cope with all these stressors alone or in combination are extensively addressed in fish. To date, studies revealing the modulation of antioxidant potential as compensatory response to multiple stressors are rather lacking. Therefore, the present work evaluated the individual and combined effects of salinity challenge, ammonia toxicity and nutritional status on oxidative stress and antioxidant status in a marine teleost, European sea bass (Dicentrarchus labrax). Fish were acclimated to normal seawater (32 ppt), to brackish water (20 ppt and 10 ppt) and to hypo-saline water (2.5 ppt). Following acclimation to different salinities for two weeks, fish were exposed to high environmental ammonia (HEA, 20 mg/L representing 50% of 96h LC50 value for ammonia) for 12 h, 48 h, 84 h and 180 h, and were either fed (2% body weight) or fasted (unfed for 7 days prior to HEA exposure). Results show that in response to decreasing salinities, oxidative stress indices such as xanthine oxidase activity, levels of hydrogen peroxide (H2O2) and lipid peroxidation (malondialdehyde, MDA) increased in the hepatic tissue of fasted fish but remained unaffected in fed fish. HEA exposure at normal salinity (32 ppt) and at reduced salinities (20 ppt and 10 ppt) increased ammonia accumulation significantly (84 h–180 h) in both feeding regimes which was associated with an increment of H2O2 and MDA contents. Unlike in fasted fish, H2O2 and MDA levels in fed fish were restored to control levels (84 h–180 h); with a concomitant increase in superoxide dismutase (SOD), catalase (CAT), components of the glutathione redox cycle (reduced glutathione, glutathione peroxidase and glutathione reductase), ascorbate peroxidase (APX) activity and reduced ascorbate (ASC) content. On the contrary, fasted fish could not activate many of these protective systems and rely mainly on CAT and ASC dependent pathways as antioxidative sentinels. The present findings exemplify that in fed fish single factors and a combination of HEA exposure and reduced seawater salinities (upto 10 ppt) were insufficient to cause oxidative damage due to the highly competent antioxidant system compared to fasted fish. However, the impact of HEA exposure at a hypo-saline environment (2.5 ppt) also defied antioxidant defence system in fed fish, suggesting this combined factor is beyond the tolerance range for both feeding groups. Overall, our results indicate that the oxidative stress mediated by the experimental conditions were exacerbated during starvation, and also suggest that feed deprivation particularly at reduced seawater salinities can instigate fish more susceptible to ammonia toxicity.

Interactive effect of high environmental ammonia and nutritional status on ecophysiological performance of European sea bass (Dicentrarchus labrax) acclimated to reduced seawater salinities

We investigated the interactive effect of ammonia toxicity, salinity challenge and nutritional status on the ecophysiological performance of European sea bass (Dicentrarchus labrax). Fish were progressively acclimated to normal seawater (32ppt), to brackish water (20ppt and 10ppt) and to hyposaline water (2.5ppt). Following acclimation to different salinities for two weeks, fish were exposed to high environmental ammonia (HEA, 20mg/L ∼1.18mM representing 50% of 96h LC50 value for ammonia) for 12h, 48h, 84h and 180h, and were either fed (2% body weight) or fasted (unfed for 7 days prior to HEA exposure). Biochemical responses such as ammonia (Jamm) and urea excretion rate, plasma ammonia, urea and lactate, plasma ions (Na+, Cl− and K+) and osmolality, muscle water content (MWC) and liver and muscle energy budget (glycogen, lipid and protein), as well as branchial Na+/K+-ATPase (NKA) and H+-ATPase activity, and branchial mRNA expression of NKA and Na+/K+/2Cl− co-transporter (NKCC1) were investigated in order to understand metabolic and ion- osmoregulatory consequences of the experimental conditions. During HEA, Jamm was inhibited in fasted fish at 10ppt, while fed fish were still able to excrete efficiently. At 2.5ppt, both feeding groups subjected to HEA experienced severe reductions and eventually a reversion in Jamm. Overall, the build-up of plasma ammonia in HEA exposed fed fish was much lower than fasted ones. Unlike fasted fish, fed fish acclimated to lower salinities (10ppt–2.5ppt) could maintain plasma osmolality, [Na+], [Cl−] and MWC during HEA exposure. Thus fed fish were able to sustain ion-osmotic homeostasis which was associated with a more pronounced up-regulation in NKA expression and activity. At 2.5ppt both feeding groups activated H+-ATPase. The expression of NKCC1 was down-regulated at lower salinities in both fed and fasted fish, but was upregulated within each salinity after a few days of HEA exposure. Though an increment in plasma lactate content and a decline in energy stores were noted for both feeding regimes, the effect was more severe in feed deprived fish. Overall, several different physiological processes were disturbed in fasted sea bass during HEA exposure while feeding alleviated adverse effects of high ammonia and salinity challenge. This suggests that low food availability can render fish more vulnerable to external ammonia, especially at reduced seawater salinities.

Hypo-osmotic stress-induced physiological and ion-osmoregulatory responses in European sea bass (Dicentrarchus labrax) are modulated differentially by nutritional status

We investigated the impact of nutritional status on the physiological, metabolic and ion-osmoregulatory performance of European sea bass (Dicentrarchus labrax) when acclimated to seawater (32ppt), brackish water (20 and 10ppt) and hyposaline water (2.5ppt) for 2weeks. Following acclimation to different salinities, fish were either fed or fasted (unfed for 14days). Plasma osmolality, [Na+], [Cl−] and muscle water content were severely altered in fasted fish acclimated to 10 and 2.5ppt in comparison to normal seawater-acclimated fish, suggesting ion regulation and acid–base balance disturbances. In contrast to feed-deprived fish, fed fish were able to avoid osmotic perturbation more effectively. This was accompanied by an increase in Na+/K+-ATPase expression and activity, transitory activation of H+-ATPase (only at 2.5ppt) and down-regulation of Na+/K+/2Cl− gene expression. Ammonia excretion rate was inhibited to a larger extent in fasted fish acclimated to low salinities while fed fish were able to excrete efficiently. Consequently, the build-up of ammonia in the plasma of fed fish was relatively lower. Energy stores, especially glycogen and lipid, dropped in the fasted fish at low salinities and progression towards the anaerobic metabolic pathway became evident by an increase in plasma lactate level. Overall, the results indicate no osmotic stress in both feeding treatments within the salinity range of 32 to 20ppt. However, at lower salinities (10–2.5ppt) feed deprivation tends to reduce physiological, metabolic, ion-osmo-regulatory and molecular compensatory mechanisms and thus limits the fish's abilities to adapt to a hypo-osmotic environment.

A review of the biology of Australian halophilic anostracans (Branchiopoda: Anostraca).

Australia has two species of Artemia: A. franciscana introduced to salt works and apparently not spreading, and parthenogenetic Artemia presently spreading widely through southwestern Australia. In addition, and unique to Australia, there are 18 described species of Parartemia in hypersaline lakes. All Parartemia use a lock and key mechanism in amplexus and hence have distinctive antennal-head features in males and thoracic modifications in females. Various factors, including climatic fluctuations and isolation, contribute to a far higher diversity in the southwest of the continent. There are few congeneric occurrences of Parartemia possibly due to their consuming largely uniform allochthonous organic matter rather than multisized planktonic algae. In P. zietziana there are 2–3 cohorts a year each persisting 3–9 months. Up to 80% of assimilation is used in respiration and at times energy balance is negative, which accounts for its continuous mortality, inconsistent growth rates and unpredictable recruitment. Many species are as osmotically competent as Artemia, but are at a disadvantage in hypersaline waters >250 g L-1 as they lack the haemoglobin of Artemia. Parartemia acidiphila and P. contracta live in markedly acid waters to pH 3.5, where dissolved carbonate and bicarbonate are unavailable, and hence they must have evolved an additional proton pump to produce ATP from endogenous CO2. Occurrences of some species have been severely curtailed by lake salinisation (which includes acidification and changes in hydroperiod), so that their continued existence is in doubt. A few species of the otherwise freshwater Branchinella occur in mainly hyposaline waters.

Floating Desalination and Water Pumping Plants as Harmful Algal Bloom Control Technologies

Harmful Algal Blooms (HABs) have significant ecological and economic effects on the marine environment and use. In recent years, researchers have been increasingly developing and testing methods to treat and control HABs. General categories or strategies proposed as HAB control technologies include mechanical, biological, chemical, genetic, and environmental controls. The authors of this paper suggest using floating desalination plants to treat or control red tides. HAB producing dinoflagellates have been shown to be sensitive to physical and chemical changes in the environment, such as changes in temperature and salinity. The typical response of dinoflagellates is to form cysts that then settle out of the water column. The discharges from a floating desalination and water pumping plant can rapidly change the temperature and salinity in the water column. These changes could be expected to induce encystment in the dinoflagellate species that form cyst and could cause mortality in those species unable to form temporary cysts. Preventing population growth, inducing encystment, or causing mortality would effectively end a HAB. Discharges from a desalination plant are temporary in nature and include hypersaline water, freshwater (hyposaline water), and heated warmer. By discharging the heated hyposaline water at a low depth in the water column, due to its lower density than seawater, the discharge would move upward towards the surface. Since the hypersaline water would be denser than seawater, by discharging it at the surface, the hypersaline water would sink. In environments where a stratified water column exists, pumping water could disrupt the stratification without the need for additional desalination. The discharges from a floating desalination plant would stress the red tide with surfacing warmer fresh water and sinking hypersaline water. The stresses caused by these disturbances can disrupt a HAB. These temperature and salinity changes that could be created by a floating desalination plant would be achieved without the discharge of chemicals or other materials that could have other detrimental environmental impacts. A good aspect of this treatment is that, with continued mixing after discharge, the water would return to ambient temperature and salinity relatively quickly with minimal effect on the marine environment. Since the dinoflagellates have been shown to react quickly to environmental changes, the temperature and salinity of the discharges could be controlled to reduce adverse impacts on other marine organisms. B

Further studies on the fairy shrimp genus Branchinella (Crustacea: Anostraca: Thamnocephalidae) in Australia, with descriptions of five new species

Branchinella is the most speciose anostracan genus in Australia and is one of a few speciose fairy shrimp genera in theworld. Two new species, B. erosa sp. nov. and B. hearnii sp. nov. live in hyposaline waters in western Western Australiaand three new species, B. herrodi sp. nov., B. anatinorhyncha sp. nov. and B. minmina sp. nov. are described from freshwaters in northern Queensland. Branchinella clandestina is synonymised with B. affinis, so that the total Australian spe-cies of Branchinella is now 39. Significant new distribution records are given for B. affinis, B. compacta and B. simplex.New morphological data is provided for B. compacta and B. wellardi to differentiate them from B. hearnii sp. nov. and B.herrodi sp. nov. respectively. Branchinella compacta and B. hearnii sp. nov. may demonstrate lock and key amplexus, while multiple tumidities on female B. erosa sp. nov. suggest possible sensory selection by males.

Concordance between realised and fundamental niches in three IberianSigaraspecies (Hemiptera: Corixidae) along a gradient of salinity and anionic composition

Summary1. We test the hypothesis that the physiological tolerance of corixids for saline conditions determines, at least partially, their occurrence along a salinity gradient that encompasses a variety of anionic compositions.2. Three species ofSigara,S. nigrolineata(fresh waters),S. scripta(hyposaline waters) andS. selecta(mesosaline and hypersaline waters) were selected, and it was predicted that species occurring in the most saline waters would be ion regulation specialists that are more tolerant of higher salinity, while species living in fresh or hyposaline waters would be generalist regulators in relation to different anions, and therefore less tolerant of higher salinity.3. Niche breadth was quantified using field data for both water conductivity and anionic composition (realised niche). In addition, physiological tolerance in relation to conductivity and anionic composition (fundamental niche) was estimated in laboratory tests using eggs, nymphs and adults of all species.4. Sigara nigrolineataadults showed the most limited conductivity tolerance and were generalists in relation to different anionic water compositions.Sigara scriptademonstrated tolerance of hyposaline and mesosaline waters and higher survival rates in sulphated waters.Sigara selectawas the only species occupying hypersaline waters that showed a preference for anion chloride.5. Sigara scriptawas the only species coexisting with the other two species. This can be explained by the overlap found in conductivity and anionic composition niche dimensions at the lower (S. nigrolineata) and upper (S. selecta) tolerance limits.6. Young life‐stages of the species showed similar responses but less tolerance of higher salinity than adults; this was the case for eggs ofS. nigrolineataand nymphs ofS. scriptaandS. selecta.7. Physiological limitations were not found in relation to fresh and less saline waters inS. selecta,so other factors, probably involving biotic interactions, may play an important role in this species.

Effects of salinity on ingestion, oxygen consumption and ammonium excretion rates of the sea cucumber Holothuria leucospilota

The sea cucumber Holothuria leucospilota is a good candidate for aquaculture, for large-scale production of this sea cucumber, it is imperative to know the effects of salinity on its physiological performance. In this study, ingestion, oxygen consumption and ammonium excretion rates of the adult sea cucumber H.leucospilota (16.98 ± 1.14 g, wet weight) at various salinity levels (18, 23, 28, 33 and 38 PSU) were studied in the laboratory. The species were acclimated for 1 week at the desired salinity before testing, and were fed with sediment from their natural habitat during this period. Results showed that the minimum ingestion rate (0.02 ± 0.01 g g−1d−1) at a salinity of 18 PSU was significantly lower than those observed at salinities of 28, 33 and 38 PSU, and there was no significant difference among the values at 23, 28, 33 and 38 PSU. The maximum value of oxygen consumption rate recorded at a salinity of 28 PSU was significantly higher than the minimum at 18 PSU, no significant differences were observed among other treatments. The ammonium excretion rates of H. leucospilota also changed significantly in response to salinity variations, the maximum value observed at a salinity of 28 PSU (0.09 ± 0.03 μM g−1h−1) being nearly five times higher than the minimum value at a salinity of 38 PSU (0.02 ± 0.01 μM g−1h−1). The O:N ratio varied as a function of salinity. Lower O:N ratios (<11.0) at salinities below 23 PSU indicated protein-dominated catabolism under hyposaline stress; the higher O:N ratio (46.5) at a salinity of 38 PSU indicated carbon-based metabolism. Results of this study indicated that the sea cucumber H. leucospilota may have a wide tolerance of salinity variation. However, it is not a very suitable species for rearing in hyposaline water. This study provides useful information for improving aquaculture management in tropical and subtropical coastal areas.

Marine shelf to paralic biofacies of Upper Triassic to Lower Jurassic deposits in Spitsbergen

The Upper Triassic to Lower Jurassic Kapp Toscana Group of Spitsbergen consists of mudstones, sandstones and shales deposited in offshore marine to paralic conditions in an extensive shelf embayment. The study focuses on microfossil-based biofacies features (mainly foraminifera, but also palynomorphs) combined with sedimentary and selected geochemical data, in relation to transgressive–regressive developments. The analysed material includes field logs and sediment samples originating from the Juvdalskampen section, central Spitsbergen.The benthic foraminiferal succession reveals three principal associations: 1) assemblages of mixed agglutinated and calcareous components, typified by medium to high diversities, indicating offshore shelf conditions; 2) assemblages consisting dominantly or entirely of agglutinated forms with low diversity, attributed to hyposaline conditions; 3) highly impoverished agglutinated assemblages or barren samples suggesting extremely brackish to freshwater environments. The marine influence is highest in the lower and upper parts, and lowest in the middle part of the Kapp Toscana Group, as indicated both by foraminiferal and palynomorph proxies. The potential of the boron concentration as a salinity indicator is demonstrated by its co-variance with biofacies features: the boron content increases with increasing salinity.The Kapp Toscana Group consists of two depositional sequences. The Storfjorden sequence (Carnian to Early Norian) starts with a transgressive systems tract formed in offshore shelf conditions with normal marine salinity and terminates at the maximum flooding event, which is succeeded by a highstand systems tract deposited in paralic (hyposaline to freshwater), prodelta to delta plain environments. The overlying Wilhelmøya sequence (Middle Norian to Bajocian) is punctuated by several hiatuses, and was deposited in hyposaline waters on a sediment-starved, prodelta shelf platform.