Different Combinations Of Salinity Research Articles

Cross-stress lipid response of Tetraselmis striata CTP4 to temperature and salinity variation

Tetraselmis striata CTP4 is a euryhaline, eurythermal microalga, rich in lipids, including omega-3 polyunsaturated fatty acids. However, little is known about how salinity and temperature affect its lipid profile. This work sought to evaluate the plasticity of the lipidome of T. striata CTP4 grown under different combinations of salinity (5, 20 and 35 ppt) and temperature (10, 20, 30 and 40 °C) by gas-chromatography and liquid-chromatography coupled to mass spectrometry. High salinity reduced phospholipid and glycolipid content and upregulated diacylglyceryl hydroxymethyltrimethyl-β-alanine betaine lipids at 20 °C. Accumulation of omega-6 fatty acids was observed at higher temperatures, with changes in glycolipid composition and reduction of lipid species esterified to polyunsaturated fatty acids. T. striata CTP4 grown at 40 °C had higher triacylglycerol productivity, although imposing severe limitations on its survival. Overall, the different combinations of salinity and temperature allowed the production of biomass with dissimilar lipid composition and nutritional value with promising biotechnological applications.

The combined effect of seawater salinity and duration on the survival and growth of eelgrass Zostera marina

Abrupt changes in salinity are considered a key cause of seagrass bed degradation. In the study, we first quantified the effects of different combinations of salinity and duration on the responses of Zostera marina shoots in terms of survivorship, morphology, growth and physiology. The recovery potential (recovery of shoots from salinity stress to be returned to original salinity level) of Z. marina shoots was assessed. The LT50 (lethal time that caused an increase in mortality to 50 % of that of the control) and EC50 (effect concentration, i.e., salinity level that caused a decrease in growth to 50 % of that of the control) were calculated to reveal the quantitative relationship between salinity and duration that resulted in limiting effects on the survival and growth of Z. marina shoots. Z. marina shoots were exposed to different combinations of water salinity [20, 25, 30 (control), 35, 40, and 45 PSU] and duration (5, 10, 15 and 20 days), and then the shoots were transferred to the control condition for 30 days under laboratory conditions. The results showed that the survival rate of shoots at the end of recovery was significantly lower than those of shoots at the end of direct salinity stress at the hypersalinity levels of 40 and 45 PSU, indicating that short-term periods of increase in water salinity would lead to long-term effects on the survival of Z. marina shoots. The total leaf area of shoots at the end of recovery was significantly higher than those of shoots at the end of direct salinity stress at salinity levels of 25–35 PSU, indicating a significant recovery potential following the salinity stress. However, a poor recovery potential was found under combinations of hypersalinity (40–45 PSU) and duration of 20 days. Regression analysis revealed that the relationship between salinity and duration was a strong power function that could limit the growth of Z. marina. Pearson correlation analysis showed that the survival and growth of Z. marina shoots exposed to different salinity levels were significantly correlated with leaf soluble sugar contents when the duration was higher than 5 days. This study will further enhance our understanding of seagrass bed degeneration induced by abrupt changes in salinity.

Polyextremophilic Chitinolytic Activity by a Marine Strain (IG119) of Clonostachys rosea.

The investigation for novel unique extremozymes is a valuable business for which the marine environment has been overlooked. The marine fungus Clonostachys rosea IG119 was tested for growth and chitinolytic enzyme production at different combinations of salinity and pH using response surface methodology. RSM modelling predicted best growth in-between pH 3.0 and 9.0 and at salinity of 0–40‰, and maximum enzyme activity (411.137 IU/L) at pH 6.4 and salinity 0‰; however, quite high production (>390 IU/L) was still predicted at pH 4.5–8.5. The highest growth and activity were obtained, respectively, at pH 4.0 and 8.0, in absence of salt. The crude enzyme was tested at different salinities (0–120‰) and pHs (2.0–13.0). The best activity was achieved at pH 4.0, but it was still high (in-between 3.0 and 12.0) at pH 2.0 and 13.0. Salinity did not affect the activity in all tested conditions. Overall, C. rosea IG119 was able to grow and produce chitinolytic enzymes under polyextremophilic conditions, and its crude enzyme solution showed more evident polyextremophilic features. The promising chitinolytic activity of IG119 and the peculiar characteristics of its chitinolytic enzymes could be suitable for several biotechnological applications (i.e., degradation of salty chitin-rich materials and biocontrol of spoiling organisms, possibly solving some relevant environmental issues).

Culture Growth of the Cyanobacterium Phormidium sp. in Various Salinity and Light Regimes and Their Influence on Its Phycocyanin and Other Pigments Content

A strain of the filamentous non N-fixing cyanobacterium Phormidium sp. isolated from the Messolonghi (W. Greece) saltworks, was cultured in the laboratory at six different combinations of salinity (20-40-60 ppt) and illumination (low-2000 lux and high-8000 lux). At salinities of 60 and 40 ppt and in high illumination (XL-8000 lux), the growth rate (μmax) presented the highest values (0.491 and 0.401, respectively) compared to the corresponding at 20 ppt (0.203). In general and at all salinities, the higher illumination (XL) gave the highest growth rates and shorter duplication time (tg) in comparison to the lower illumination (L). On the contrary, phycocyanin, phycoerythrin and allophycocyanin production was extremely increased in the lower illumination (L) in all salinities, from ~14 fold at 40 and 60 ppt to 269 fold at 20 ppt of those corresponding to higher illumination (XL). Similar analogies were also recorded for the other two billiproteins. Chlorophyll-a content was also higher in lower illumination at all salinities in contrast to total carotenoids that did not exhibit such a pattern. The high growth rate and high phycocyanin content along with the rapid sedimentation of its cultured biomass can set this marine Phormidium species as a promising candidate for mass culture.

Sustainable Innovation in Membrane Technologies for Produced Water Treatment: Challenges and Limitations

Discharged water from the oil and gas fields is a common type of wastewater called produced water (PW). It consists of different combinations of salinities, oils, and mineral deposits. Growing industrial demand, accelerated urbanization, and rapid population growth are putting enormous strain on the world’s water supply. Based on sustainable freshwater supplies, North Africa, the Middle East, and South Asia confront the ultimate water shortages threat. Proper implementation of innovative membrane technologies in wastewater treatment is considered a solution towards tackling water insecurity and sustainability. Different types of innovative membrane technologies used for produced water treatment were considered in this work. A framework of innovative membrane technology was studied for industrial wastewater with direct contribution to the environmental and economical sustainability factors, taking into consideration grand challenges and limitations in energy costs and environmental constraints. Treated produced water can be utilized in irrigation providing many benefits only if the desalination sector is mature and fully developed.

Freshening increases the susceptibility to heat stress in intertidal mussels (Mytilus edulis) from the Arctic

Temperatures in the Arctic are increasing at a faster pace than at lower latitudes resulting in range expansion of boreal species. In Greenland, the warming also drives accelerating melt of the Greenland Ice Sheet resulting in more meltwater entering Greenland fjords in summer. Our aim was to determine if increasing summer temperatures combined with lower salinity can induce the expression of stress-related proteins, for example, heat shock protein, in boreal intertidal mussels in Greenland, and whether low salinity reduces the upper thermal limit at which mortality occurs. We conducted a mortality experiment, using 12 different combinations of salinity and air temperature treatments during a simulated tidal regime, and quantified the change in mRNA levels of five stress-related genes (hsp24, hsp70, hsp90, sod and p38) in surviving mussels to discern the level of sublethal stress. Heat-induced mortality occurred in mussels exposed to an air temperature of 30°C and mortality was higher in treatments with lowered salinity (5 and 15‰), which confirms that low habitat salinity decreases the upper thermal limit of Mytilus edulis. The gene expression analysis supported the mortality results, with the highest gene expression found at combinations of high temperature and low salinity. Combined with seasonal measurements of intertidal temperatures in Greenland, we suggest heat stress occurs in low salinity intertidal area, and that further lowered salinity in coastal water due to increased run-off can make intertidal bivalves more susceptible to summer heat stress. This study thus provides an example of how different impacts of climate warming can work synergistically to stress marine organisms.

The habitat preference of mangrove crabs in different mangrove forests of Penang, North Peninsular Malaysia

Different crab assemblage compositions may result in distinct pathways in mangrove ecosystem function, attributed to specific preferences and habitat selection criteria by each crab species. This study assessed the preference of crabs to different mangrove forests at Balik Pulau, Penang, Malaysia across temporal scales of four months and spatial scales across three forests. Sites were characterized by Avicennia, Rhizophora and Bruguiera species. Crabs were sampled using hand-catch method, which was then preserved in 70% ethanol and identified to the lowest taxonomic level possible. Environmental variables were determined by in-situ and ex-situ analysis and comprised the collection of canopy cover, root cover, surface temperature, sediment salinity and organic matter data. PERMANOVA analysis showed there was a difference in crab abundance and environmental variables across Month and Forest (p < 0.05). SIMPER analysis revealed that the Grapsidae family dominated mangroves of Balik Pulau, with Perisesarma eumolpe and Perisesarma foresti found to be most abundant in Avicennia and Bruguiera forests respectively. However, in the Rhizophora forest, dominant crab species varied, with Parasesarma sp2. and Perisesarma indiarum found in high abundance in June and August, respectively. In October and December, however Perisesarma foresti was the major contributor to patterns observed in crab assemblage composition in Rhizophora forest. BEST correlation varied among month and forest, with different combinations of salinity, pH, canopy cover and root density explaining patterns in crab assemblages.

Embryonic and larval development of the caridean shrimp Palaemon argentinus (Decapoda, Caridea): effects of salinity and diet

Abstract The caridean shrimp Palaemon argentinus is a species of commercial and ecological interest. Its numerous larval stages, the lack of knowledge on their nutritional requirements, and their ability to survive in a wide range of salinities raise questions on the optimum conditions for larval rearing in captivity. The present study was aimed at evaluating embryonic development under different salinities and larval development under different combinations of salinities and diet regimes, in order to define alternative, cheaper culture conditions. We tested salinities usually encountered by the species in natural habitats (0.1, 1 and 5 ppt) and a highly protein-inert diet (Tetracolor®) as a potential replacement for live food (nauplii of Artemia salina). The incubation period and fecundity were similar among salinity treatments. Overall, the number of survival days and percentage of zoeae that moulted two, three and four times were higher when embryogenesis occurred at 5 ppt and when larvae were exposed to 5 ppt. These results suggest that the conditions experienced by embryos affect the performance of the first larval stages, and probably reflect the lower energetic requirements of zoeae to osmoregulate as water and haemolymph osmolarity become closer. On the other hand, larval performance was better when fed A. salina nauplii than Tetracolor®. The latter may not cover the nutritional requirements of zoeae or may have low digestibility due to insufficient enzymes in the undeveloped larval digestive system. Based on the present results, we conclude that a salinity of 5 ppt combined with a diet consisting of Artemia sp. nauplii is optimal for larval culture at early stages.

Hydrodynamic classification of submerged Thermal-Saline Inclined Single-Port discharges

The discharge of warm effluent from thermal power plants and saline effluent from desalination sites in aquatic environments can, if the sufficient dilution is not attained, subsequently lead to severe environmental damage in the water column or surrounding waterbed. This paper attempted to experimentally assess an inclined single-port discharge system for thermal-saline effluent in a still, homogeneous water environment. The experiments were conducted for different combinations of salinity and warmth of the effluent and at three discharge angles of 30°, 45° and 60°.The results of this study developed a classification chart for Thermal-Saline Inclined Single-Port jets. In fact, the charts are applicable to thermal-saline jets with a new layer added to the charts proposed in previous studies for positive and negative jets. This research has also provided the criteria for thermal-saline buoyant jets to design, including the discharge angle and the proper combinations of effluent salinity and warmth.

Early development of the ectoparasite Caligus rogercresseyi under combined salinity and temperature gradients

One of the pathogens causing the highest economic impacts on the Chilean salmon industry is the ectoparasite copepod Caligus rogercresseyi, whose abundance is strongly influenced by environmental variables (e.g. salinity and temperature). Infested fish with sea lice reduces appetite, food-conversion efficiency and increase stress level, which results in decreased growth. The skin wounds, caused by the ectoparasite feeding, leave fish exposed to secondary infections and antiparasitics treatment expenses are high. To evaluate the impact of environmental variables on the early development of C. rogercresseyi, egg strings were obtained from mature females (reared in laboratory conditions) and exposed to different combinations of salinity (14, 20, 26 and 32 PSU) and temperature (6, 9, 12, 15 and 18°C). The hatching success and time, pelagic life time, survival and size of nauplius I, nauplius II and copepodid were quantified. Our results indicate that salinity and temperature have a significant effect on the hatching success of this parasite. Salinities between 26 and 32 PSU result in a hatching success of 100%, whereas lower salinities (14 PSU) reduce hatching success by 60% (at all experimental temperatures) generating an increase in mortality of these early developmental stages. A temperature reduction from 18°C to 6°C in culture conditions significantly extended the incubation time of C. rogercresseyi by 50%. Specifically, temperature had a higher impact on nauplius I and nauplius II larvae, increasing development times to 50 and 100 h respectively, when temperature was decreased to 6°C. Although combination of salinity and temperature have a significant effect on hatching time and survival in C. rogercresseyi, the combination of these variables had no impact on the size of nauplius I, nauplius II and copepodid stage. Thus, the effects on the survival and pelagic life time of the early stage of C. rogercresseyi, might substantially affect the fitness of the species under fluctuating conditions of salinity and temperature.

Gene expression and physiological responses to salinity and water stress of contrasting durum wheat genotypes.

Elucidating the relationships between gene expression and the physiological mechanisms remains a bottleneck in breeding for resistance to salinity and drought. This study related the expression of key target genes with the physiological performance of durum wheat under different combinations of salinity and irrigation. The candidate genes assayed included two encoding for the DREB (dehydration responsive element binding) transcription factors TaDREB1A and TaDREB2B, another two for the cytosolic and plastidic glutamine synthetase (TaGS1 and TaGS2), and one for the specific Na(+) /H(+) vacuolar antiporter (TaNHX1). Expression of these genes was related to growth and different trait indicators of nitrogen metabolism (nitrogen content, stable nitrogen isotope composition, and glutamine synthetase and nitrate reductase activities), photosynthetic carbon metabolism (stable carbon isotope composition and different gas exchange traits) and ion accumulation. Significant interaction between genotype and growing conditions occurred for growth, nitrogen content, and the expression of most genes. In general terms, higher expression of TaGS1, TaGS2, TaDREB2B, and to a lesser extent of TaNHX1 were associated with a better genotypic performance in growth, nitrogen, and carbon photosynthetic metabolism under salinity and water stress. However, TaDREB1A was increased in expression under stress compared with control conditions, with tolerant genotypes exhibiting lower expression than susceptible ones.

Synergistic effects of altered salinity and temperature on estuarine eelgrass (Zostera marina) seedlings and clonal shoots

Salinity and temperature are among the most important factors determining eelgrass distribution and performance. Plants in estuarine environments experience large variations in both on a seasonal basis and exceptionally warm summers have caused massive die-backs of eelgrass in many areas. We investigated experimentally how different combinations of salinity and temperature affect the physiological performance of adult eelgrass (Zostera marina) shoots and seedlings. Plants were exposed to different combinations of salinity (salinity 5, 12.5 and 20) and temperature (15, 20 and 25°C) in a 5-week aquarium experiment. Plants responded in general negatively to decreasing salinity and increasing temperature and the combination of high temperature and low salinity resulted in markedly higher mortality rates and lower leaf production when compared to plants held at more optimal combinations of salinity and temperature. Seedlings had higher absolute mortality, while adult shoots were relatively more sensitive to unfavorable levels of salinity. Leaf tissue sucrose concentrations in both life stages decreased at low salinity, whereas salinity and temperature resulted in contrasting starch concentrations between seedlings and adult shoots. Our results show that altered salinity and temperature may have negative synergistic effects on eelgrass performance. Future climate changes may thus have serious impacts on eelgrass survival and performance.

Metabolic Activity, Reproduction and Survival of the High Littoral Fringe Copepod Itunella muelleri (Harpacticoida: Canthocamptidae) at Different Combinations of Salinities and Temperatures

Survival, metabolic and reproductive activity of Itunella muelleri was tested in several combinations of temperatures (2°-30°C) and salinities (from fresh water to salinity of 34‰). Proportions of individuals alive after 18 or 22 days was high in all experimental combinations except in fresh water at 2°C and at 30°C at salinities of 4 and 16‰. Metabolic activity, as measured by the production of faecal pellets, was low in fresh water regardless of temperature. Metabolic activity was also very low at 2°C regardless of salinity. Maximum activity was found at 20°C and 22°C with little difference between salinities of 4, 8, 16, and 32‰. Production of nauplii during the first 29 days was nil in fresh water regardless of temperature, and also nil at 2°C and 30°C regardless of salinities. The maximum production was found in the combination of 22°C and salinity of 16‰. The results are discussed in relation to expected ambient conditions in the natural habitat of the species.

Variation in penaeid shrimp growth rates along an estuarine salinity gradient: Implications for managing river diversions

Freshwater inflows from river diversions may affect nekton populations by altering the salinity and temperature of estuarine waters. To investigate the influence of these environmental variables on the growth and survival rates of brown shrimp Farfantepenaeus aztecus and white shrimp Litopenaeus setiferus, we conducted field experiments in May and September 2007 to expose experimental animals to the range of different combinations of salinity and water temperature that commonly occur in an estuarine environment. Growth rates for shrimp held in mesocosms for approximately 7 days were compared among four locations and three treatments; locations were identified by the dominant marsh vegetation and distance from the Gulf of Mexico (low to high salinity: Intermediate, Brackish, Saline UE = Saline Up Estuary, Saline DE = Saline Down Estuary). At each location, the treatments were replicated four times and included shallow water with additional food, shallow water without food added, and deeper water (an attempt to expose animals to lower temperatures). Our experiments were designed to test the null hypothesis that shrimp growth and survival rates did not differ by location or treatment. Both brown shrimp and white shrimp grew more slowly at the Intermediate than higher salinity locations. Potential prey (benthic infauna) biomass was relatively low at both the Intermediate and Brackish locations in May, and both shrimp species consistently grew faster in mesocosms where food was added. We conclude that reduced growth in low salinity environments is likely due to the combined effects of increased metabolic costs and less food in these areas. River diversions that reduce estuarine salinities over a large portion of available habitat during peak recruitment periods may reduce overall growth rates and shrimp productivity in the affected areas.

Effect of salinity and water stress during the reproductive stage on growth, ion concentrations, Δ13C, and δ15N of durum wheat and related amphiploids

The physiological performance of durum wheat and two related amphiploids was studied during the reproductive stage under different combinations of salinity and irrigation. One triticale, one tritordeum, and four durum wheat genotypes were grown in pots in the absence of stress until heading, when six different treatments were imposed progressively. Treatments resulted from the combination of two irrigation regimes (100% and 35% of container water capacity) with three levels of water salinity (1.8, 12, and 17 dS m(-1)), and were maintained for nearly 3 weeks. Gas exchange and chlorophyll fluorescence and content were measured prior to harvest; afterwards shoot biomass and height were recorded, and Delta(13)C, delta(15)N, and the concentration of nitrogen (N), phosphorus, and several ions (K(+), Na(+), Ca(2+), Mg(2+)) were analysed in shoot material. Compared with control conditions (full irrigation with Hoagland normal) all other treatments inhibited photosynthesis through stomatal closure, accelerated senescence, and decreased biomass. Full irrigation with 12 dS m(-1) outperformed other stress treatments in terms of biomass production and physiological performance. Biomass correlated positively with N and delta(15)N, and negatively with Na(+) across genotypes and fully irrigated treatments, while relationships across deficit irrigation conditions were weaker or absent. Delta(13)C did not correlate with biomass across treatments, but it was the best trait correlating with phenotypic differences in biomass within treatments. Tritordeum produced more biomass than durum wheat in all treatments. Its low Delta(13)C and high K(+)/Na(+) ratio, together with a high potential growth, may underlie this finding. Mechanisms relating delta(15)N and Delta(13)C to biomass are discussed.

Combined effects of temperature and salinity on critical thermal minima of pacific white shrimp Litopenaeus vannamei (Crustacea: Penaeidae)

Critical thermal minima (CTMin) were determined for the Pacific white shrimp Litopenaeus vannamei juveniles from four different acclimation temperatures (15, 20, 25, and 30 °C) and salinities (10‰, 20‰, 30‰, and 40‰). The lowest and highest CTMin of shrimp ranged between 7.2 °C at 15 °C/30‰ and 11.44 °C at 30 °C/20‰ at the cooling rate of 1 °C h −1. Acclimation temperature and salinity, as well as the interaction of both parameters, had significant effects on the CTMin values of L. vannamei ( P<0.01). Yet, the results showed a much more profound effect of temperature on low thermal tolerance of juveniles. Only 40‰ salinity had an influence on the CTMin values ( P<0.01). As the acclimation temperature was lowered from 30 to 15 °C thermal tolerance of the shrimp significantly increased by 3.25–4.14 °C. The acclimation response ratio (ARR) of the Pacific white shrimp exposed to different combinations of salinity and temperature ranged between 0.25 and 0.27. When this species is farmed in sub-tropical regions, its pond water temperature in the over-wintering facilities (regardless of the water salinity level) must never fall below 12 °C throughout the cold season to prevent mortalities.

Hematocrit and plasma osmolality values of young-of-year shortnose sturgeon following acute exposures to combinations of salinity and temperature

Little is known about the physiological capabilities of young-of-year (YOY) shortnose sturgeon. In this study, plasma osmolality and hematocrit values were measured for YOY shortnose sturgeon following 48-h exposures to 12 different combinations of salinity and temperature. Hematocrit levels varied significantly with temperature and age, and plasma osmolalities varied significantly with salinity and age. Plasma osmolality and hematocrit values were similar to previously published values for other sturgeons of similar age and size in similar treatment conditions.

Survival and behavioral characteristics of amphidromous goby larvae of Sicyopterus japonicus (Tanaka, 1909) during their downstream migration

To understand the ecology and environmental tolerances of newly hatched larvae of the amphidromous fish Sicyopterus japonicus during their downstream migration, the salinity tolerance of eggs, 0–15 day old larvae, and adults, and the temperature tolerance, specific gravity and phototaxis of hatched larvae were examined. Tolerances of adults were measured as survival after a 24 h challenge in freshwater (FW), brackish water (1/3 SW) and seawater (SW). The survival rate of adult S. japonicus was 100% in FW and 1/3 SW, while none survived in SW. Hatching success of eggs (30 eggs each) was significantly higher in FW (mean: 73%) and 1/3 SW (73%) than in SW (19%). Tolerance of newly hatched larvae to salinity and temperature was investigated in different combinations of salinities (FW, 1/3 SW and SW) and temperatures (18, 23 and 28 °C). Larval survival was significantly different in each salinity and temperature. Survival rate was significantly higher in 1/3 SW than in FW and higher in SW than in FW at 23 °C and 28 °C. At the latter part of the experiment, there was no survival in FW and at 28 °C. Survival was higher in lower temperatures, but larval development did not occur in FW. Specific gravity of newly hatched larvae was 1.036 at 28 °C and 1.034 at 23 °C. When exposed to a light source on one side of an aquarium, larval distribution was not affected. Our results indicated larval S. japonicus are more adapted to brackish water and seawater than freshwater, while the adults and eggs are more adapted to freshwater and brackish water than seawater. This is consistent with their amphidromous life history with growth and spawning occurring in freshwater and the larval stage utilizing marine habitats.

Growth and blood chemistry of Atlantic halibut (Hippoglossus hippoglossus L.) in relation to salinity and continuous light

In order to study the possible interactive effects of salinity and photoperiod on growth, feed conversion, and blood chemistry in juvenile halibut, 2,604 (initial mean weight 26.8 g ± 0.2 SEM) juvenile halibut were exposed to six different combinations of salinities (13, 21, or 27‰) and photoperiods [continuous light, C and simulated natural photoperiod (65°N), SNP] for 129 days. Improved (10–20%) growth and 10–24% higher feed conversion efficiency were observed at low and intermediate salinities compared to the high salinity groups. Improved feed conversion efficiency (20%) and temporary growth enhancing effects (10%) of continuous light were observed, but effects faded out as day length in the simulated natural photoperiod group increased. No interactive effects of photoperiod and salinity on growth feed conversion or measured blood chemistry variables (blood sodium, pH level, haematocrit, bicarbonate content, and total carbon dioxide). It is suggested that juvenile Atlantic halibut should be reared at low and intermediate salinities and at continuous light, as this will improve growth and increase feed conversion efficiency.

The effects of temperature and salinity on larval development of Armases rubripes Rathbun, 1897 (Brachyura, Grapsoidea, Sesarmidae), and the southern limit of its geographical distribution

The southernmost stable population of Armases (= Metasesarma) rubripes (Brachyura, Grapsoidea, Sesarmidae) is found in Montevideo, Uruguay, in the northeastern coast of the Rio de la Plata estuary. Isolated individuals have seldom been collected in the southwestern coast of this huge estuary. Since pelagic larvae are primarily responsible for the dispersion of A. rubripes, and crab larvae are generally less tolerant than adults to extreme environmental conditions, we tested the survival and intermolt period of zoeae in different combinations of salinity (10, 20, and 30 psu) and temperature (16 and 20 °C). These salinity and temperature conditions are usually found in the estuary and adjacent waters during spring and summer. We found that the survival rate of the larvae increased and they developed faster at 30 psu and 20 °C. It is unlikely that larvae from the Montevideo population of A. rubripes could be transported south and westward due to the hydrographic conditions of the region. The Rio de la Plata seems to function as a biogeographic barrier to A. rubripes, and probably to other crab species as well. However, this barrier is not absolute: it hinders, but does not entirely prevent, the dispersal of larvae.