The effect of environmental factors on the absorption of amino acids by isolated gill tissue of the bivalve, Mya arenaria (L.)

The absorption of amino acids by isolated gill tissue of Mya arenaria (L.) was examined under conditions in which the environmental temperature, salinity, and pH were varied experimentally. A decrease in salinity resulted in a fall in amino-acid uptake. The V_max of L-histidine uptake increased with temperature, the Q₁₀ for the range 5° to 15 °C being 2.64. No significant effect of pH on amino-acid absorption was observed over the pH range 6.2–8.8. These results emphasize the need clearly to specify the experimental conditions when substrate uptake values are used to calculate the contribution made by any extra-alimentary absorption route to the nutritional economy of an animal.     

Physiological responses of a green algae (<Emphasis Type="Italic">Ulva prolifera</Emphasis>) exposed to simulated acid rain and decreased salinity

In order to evaluate the combined effects of simulated acid rain (SAR) and salinity on the physiological responses of macroalgae, Ulva prolifera was cultured under three salinity treatments (5, 10, 25 ‰) and at different pH, i.e., at pH 4.4 (C), pH 4.4(F), where the pH of the culture increased from 4.4 to approximately 7.8 during the cultivation period, or in absence of SAR at pH 8.2(C), at 100 μmol(photon) m^–2 s^–1 and 20°C. Compared to 25‰ salinity, Relative growth rate (RGR) of U. prolifera was enhanced by 10‰ salinity, but decreased by 5‰ salinity. No significant differences in RGR were observed between the pH 8.2(C) and pH 4.4(F) treatments, but the chlorophyll a content was reduced by SAR. Negative effects of SAR on the photosynthesis were observed, especially under low salinity treatments. Based on the results, we suggested that the U. prolifera showed a tolerance to a wide range of salinity in contrast to the low pH induced by acid rain.     

Environmental factors affecting hatching of rotifer (Brachionus plicatilis) resting eggs

Hatching experiments were carried out on a population of Brachionus plicatilis (Dor strain) resting eggs produced in batch laboratory cultures under controlled conditions and then stored for at least one month at 4 °C in the dark. Light was found to be obligatory for termination of dormancy. Over the temperature range of 10–30 °C (at 9.0‰ salinity), hatching was optimal (40–70%) at 10–15 °C and decreased linearly with the rise in incubation temperature. Resting eggs incubated over a salinity range of 9–40‰ (at 15 °C) showed optimal hatching at 16‰. Incubation of resting eggs in distilled water permitted normal embryonic development, but neonates died at eclosion. Presence of algae, Chlorella stigmatophora (0.5 × 10⁶ cell ml^?1), was found to aid hatching.     

Improving effect of vegetation on the coastal salt marshes in Yancheng,Eastern China: A five-year observation (2013–2017)

Coastal wetlands reclamation is facing the problem of salinization. Along with the alternation of ecosystem status, studying the following effect on soil properties becomes emergency. Here we reported the pH, salinity and elemental content (mainly metals) variation affected by the vegetation situations, water sources and geographic positions. The results showed that vegetation could lead the pH and salinity of seawater zones closer to that of freshwater zones in both spatial and time scales. Spartina alterniflora (SA) was the most efficient species among the investigated plants, causing decreases of 0.15–0.69 in pH and 2.250–3.821 in salinity. This result might be caused by the absorption of Ca and K from salt marshes by SA and Suaeda salsa (SS), due to the fact that the component content of calcium (all reduced to approximate one-third) and potassium (reduced in some samples) both decreased. Meanwhile, vegetation could improve soil in seawater zones in Fe content with no extra negative influences in elemental analysis. Thus, ecological engineered vegetation indicated great potential in alternating coastal salt marshes to favorable wetlands or farmlands with almost primitive ecosystem. The results might be significant for ecological engineering and agricultural management in future.     

Effects of temperature and salinity on the larvae of two species of rhizocephalan (Crustacea: Cirripedia)

Summary

Responses of larvae of two rhizocephalan species to changes in seawater temperature and salinity were studied under laboratory conditions. Peltogasterella gracilis parasitizes the hermit crab Pagurus pectinatus, which occurs at stable salinity and gradually changing temperature in summer. Sacculina polygenea is a parasite of the crab Hemigrapsus sanguineus, which lives in the intertidal zone in summer where salinity and temperature can fluctuate during the day. The development of both species is comprised of five naupliar stages and the cyprid stage, and it was considered successful if more than 50% of the nauplii attained the cyprid stage. P. gracilis nauplii successfully developed at 12–20°C and 30–34‰, but at 22°C successful development occurred in a narrower salinity range (32–34‰). All nauplii died both at 25°C and in 26‰. S. polygenea nauplii successfully reached the cyprid stage at higher temperatures (18–25°C) and a wider salinity range (18–34‰) than P. gracilis nauplii, but at 12°C and 16‰ larval development of S. polygenea was suppressed. Under favorable conditions, naupliar development lasted 3.5 days in P. gracilis and 2–3 days in S. polygenea. The cyprids of both rhizocephalan species demonstrated a greater resistance to temperature and salinity changes than nauplii. However, P. gracilis cyprids were active in a narrower salinity range (16–34‰), as compared to S. polygenea cyprids (8–34‰). Under favorable conditions the cyprids of both species survived for 6 to 10 days.     

Isolation and evaluation of a strain of Pyropia yezoensis (Bangiales,Rhodophyta) resistant to red rot disease

Red rot disease (Pythium porphyrae) resistant strains of Pyropia yezoensis, AP1 and AP2, were isolated from live cells taken from lesions on infected P. yezoensis blades. The degree of resistance of these strains to red rot disease was evaluated over a range of environmental conditions including temperature (10, 15, and 20 °C), salinity (20, 26, and 32 ppt), and pH (7.5, 8.0, and 8.5). These conditions are within the range that red rot disease naturally occurs on Pyropia blades. P. yezoensis and Pyropia suborbiculata with low and high partial resistance to red rot disease, respectively, were used as controls. Infection with red rot disease occurred under all environmental conditions. The incidence, severity, and expansion of the disease increased with increasing temperature and decreasing salinity and pH. The resistance of the strains P. yezoensis-AP1 and P. yezoensis-AP2 was higher than that of P. yezoensis, but lower than that of P. suborbiculata. The degree of resistance was not significantly different between the AP1 and AP2 strains. These strains can therefore be considered to exhibit stable partial resistance to P. porphyrae, and as a good starting point for the development of more resistant strains that will prevent or reduce the incidence of red rot disease on Pyropia farms.     

Effects of temperature,salinity and their interaction on growth of Japanese Gambierdiscus spp. (Dinophyceae)

Marine toxic dinoflagellates of the genus Gambierdiscus are the causative agents of ciguatera fish poisoning (CFP), a seafood poisoning that is widespread in tropical, subtropical and temperate regions of the world. In the main island of Japan, distributions of Gambierdiscus australes, Gambierdiscus scabrosus and two phylotypes of Gambierdiscus spp. type 2 and type 3, have been reported. To discuss the bloom dynamics of these Japanese species/phylotypes of Gambierdiscus, first we tested six culture media to optimize growth conditions and then clarified the effects of temperature and salinity and temperature–salinity interactions on growth. All strains of the species/phylotypes tested showed the highest cell yields when they were cultivated in IMK/2 medium. G. australes, G. scabrosus and Gambierdiscus sp. type 2 grew in the range 17.5–30 °C, whereas Gambierdiscus sp. type 3 grew in 15–25 °C. The semi-optimal temperature ranges (≥80% of the maximal growth rate) of the former three species/phylotypes were 19–28 °C, 24–31 °C and 21–28 °C, respectively, whereas that of the latter phylotype was 22–25 °C. Hence, Gambierdiscus sp. type 3 may be adapted to relatively lower water temperatures of ≤25 °C. In contrast, G. australes, G. scabrosus and Gambierdiscus sp. type 2 presumably possess adaptability to relatively high water temperatures. The optimal temperature for G. scabrosus was 30 °C, whereas the optimal temperature for the others was 25 °C. G. australes and Gambierdiscus sp. type 3 grew in a salinity range of 25–40 whereas G. scabrosus and Gambierdiscus sp. type 2 grew in salinity 20–40. Furthermore, the semi-optimal salinity range of G. australes, G. scabrosus, Gambierdiscus spp. type 2 and type 3 were salinity 27–38, 24–36, 22–36 and 29–37, respectively. Among the species/phylotypes, G. scabrosus and Gambierdiscus sp. type 2 grew even at salinity 20 where the others did not grow, thus possessing adaptability to low salinity waters. Our results clearly demonstrate that the optimal and tolerable temperature–salinity conditions differ among Japanese Gambierdiscus species/phylotypes. Considering these results, temperature–salinity interactions may play an important role in bloom dynamics and the distribution of the Gambierdiscus species/phylotypes in Japanese coastal waters.     

Picophytoplankton predominance in hypersaline lakes (Transylvanian Basin,Romania)

The occurrence and importance of photoautotrophic picoplankton (PPP, cells with a diameter <2 μm) was studied along a trophic and salinity gradient in hypersaline lakes of the Transylvanian Basin (Romania). The studied lakes were found to be rich in PPP, with abundances (maximum 7.6 × 10⁶ cells mL^?1) higher than in freshwater and marine environments of similar trophic conditions. The contribution of PPP to the total phytoplankton biovolume did not decrease with increasing trophic state as it was generally found in other aquatic environments. Regardless of the trophic conditions, the contribution of PPP could reach 90–100 % in these hypersaline lakes. We hypothesized that the PPP predominance might be the result of the low grazing pressure, since heterotrophic nanoflagellates (the main grazers of PPP) were absent in the studied samples. There were significant differences in community composition among the lakes along the salinity gradient. CyPPP predominated in less saline waters (mainly below 5 %), while EuPPP were present along the entire salinity range (up to 18.7 %), dominating the phytoplankton between 3 and 13 % salinity. Above 13 % salinity, the phytoplankton was composed mainly of Dunaliella species.     

Combined effects of physicochemical variables (pH and salinity) on sperm motility: characterization of sperm motility in European sea bass Dicentrarchus labrax

Gamete activation in fish is an important step in terms of artificial fertilization of oocytes, cryopreservation studies and other experimental manipulations. Salinity and pH differences in activation media affect to sperm motility and fertilizing ability. These experiments were therefore designed to investigate the combined effects of pH (range 5.0–9.0) and salinity (20, 30, 37, and 45‰) of activation media on sperm motility of European sea bass Dicentrarchus labrax. The best results were obtained at salinity 37‰ and a pH of 9.0. Our results also demonstrated that non-progressive motility at salinity 45‰ was observed in the range of 5.0–9.0 pH. In conclusion, spermatozoa can be motile at a wide range of pH and salinity values although the percent of motile spermatozoa and motility duration are negatively affected by low pH values.     

Inversion of sucrose with β-d-fructofuranosidase (invertase) immobilized on bead DEAHP-cellulose: Batch process

The inversion of sucrose with β-d-fructofuranosidase (EC 3.2.1.26) immobilized by an ionic bond on bead cellulose containing weak basic N,N-diethylamino-2-hydroxypropyl groups has been investigated. The immobilized enzyme is strongly bound at an ionic strength up to 0.1 M in the pH range 3–6. The amount adsorbed is proportional to porosity and to the exchange capacity of the ion exchange cellulose, reaching values up to 200 mg/g dry carrier, with an activity in 10% sucrose solution at 30°C, pH 5, >8000 μmol min^?1 g^?1. The inversion of sucrose with immobilized β-d-fructofuranosidase was carried out in a stirred reactor. The dependence of activity on pH (3–7), temperature (0–70°C) and concentration of the substrate (2–64 wt%) were determined, and the inversion was compared with that obtained using non-immobilized enzyme under similar conditions. The rate of inversion at low substrate concentration (2–19 wt%) was described by Michaelis-Menten kinetics.     

Diversity, distribution and ecology of water mites (Acari: Hydrachnidia and Halacaridae) in high Alpine lakes (Central Alps, Italy)

Information on water mite assemblages from high elevation lentic biotopes is scant. A survey of 14 small Alpine lakes located between1900 and 2400 m a.s.l. in Italy resulted in the discovery of 17 species of Hydrachnidia and a single species of freshwater Halacaridae. Arrenurus conicus and Lebertia tuberosa were the most widespread and abundant species; Lebertia sefvei, Lebertia rufipes, Oxus setosus, Panisus torrenticolus and Sperchon glandulosus were also widely distributed but relatively less abundant. Atractides fissus and Arrenurus conicus are recorded for the first time from Italy. In contrast to mid/low elevation lakes and ponds, water mite assemblages of alpine lakes are less diverse and are composed mainly of rheo- and crenobiontic taxa, most of which are cold-stenothermic. Typical standing water dwellers represented only a small fraction (23%) of the species sampled. A principal component analysis conducted on lake environmental variables resulted in a clear separation of the lakes mainly based on ionic contents, pH and temperature. Water mites seem to be less influenced by these factors than by temperature fluctuations and habitat stability and heterogeneity. We conclude with some considerations of the influence of abiotic and biotic factors on the altitudinal and latitudinal distribution pattern of water mites.     

Osmotic and ionic regulation in the western rock lobster Panulirus longipes (Milne-Edwards)

The western rock lobster, Panulirus longipes (Milne-Edwards) is poikilosmotic over its tolerated salinity range, 25–45 ‰. Blood sodium is accumulated while chloride concentration is reduced. Sodium and chloride vary directly with the external salinity, although maintaining their differences in the same proportions as at normal salinity (36.0 ‰). Calcium is accumulated, ranging from over 150% at salinity 20 ‰ to about 117% at salinity 45 ‰. Potassium concentration is equivalent to the external at normal salinity, but is increased with lowered and decreased with raised salinity. Magnesium is reduced to about one-third that of the external concentration over the salinity range 20–40 ‰, but regulation begins to break down at 45 ‰. Individual ions exhibit, therefore, a range of regulation types, from poikilosmotic to homoiosmotic.Equilibrium for sodium, chloride, and calcium is attained in 10 h at salinities of 25, 30, 40 and 45 ‰ respectively. Rate constants for this exchange are linearly related to salinity differential, and rapid osmotic adjustment is by high permeability, equal in both directions, probably mainly via the gills. Muscle appears to act as a salt pool for sodium, chloride, and potassium but not for magnesium and calcium. Salt-loading causes a slight salt diuresis, the salts being excreted, probably via the gills. Except for calcium, there is no excretion of salt into the gut, but there is evidence of an exchange of chloride with another anion. Magnesium excretion is slow, and in the absence of osmotic stress possibly occurs via the antennal glands. All the ions examined appear to be regulated independently.     

Partial purification and characterization of the major midgut proteases of grass grub larvae (Costelytra zealandica,Coleoptera: Scarabaeidae)

The major proteases of the grass grub (Costelytra zealandica) larval midgut have been identified, partially purified and characterized. Identification was made initially on the basis of hydrolysis of synthetic substrates (blocked and partially blocked esters and amides of specific amino acids), thus classifying the activities into different classes of endo- and exopeptidases. A range of inhibitors specific to different classes of proteases were used to confirm the presence of trypsin, chymotrypsin, elastase, leucine aminopeptidase and carboxypeptidases A and B and to establish the absence of thiol- and metallo-endopeptidases. The dominant endopeptidase in the midgut is trypsin, which is present in four forms, distinguishable by net charge, but indistinguishable either in terms of Michaelis-Menten parameters (K_m and k_cat) or in molecular weight (23,000). The pH optimum lies between pH 9–10. Leucine aminopeptidase has a molecular weight of 91,000 and a pH optimum at pH 8.0. Carboxypeptidase A has a molecular weight of 43,000 and a pH optimum at pH 8.5. All enzymes retained substantial activity at pH 7.0–7.1, the pH of the midgut lumen, where the bulk of the activity was located. Protease levels in the hindgut (or fermentation sac) were 1–5% of those in the midgut. The range of enzymes appears sufficient for complete breakdown of ingested protein.     

Study of copper(II) and nickel(II) ternary complexes involving tertiary amines and phenyl or hydroxylphenyl substituted amino acids

Formation constants of ternary complexes MAL, where M = Cu(II) or Ni(II). A = 2.2′bipyridyl. 1, 10-phenanthroline, and L = 3.4-dihydroxyphenylalanine (dopa), tyrosine, or phenylalanine have been determined by using the computer program SCOGS. It is observed that dopa coordinates with Cu(II)-A and Ni(II)-A through the aminocarboxylate and only over the pH range 3–8, though the ligand coordinates with free Cu(II) ion from the amino carboxylate end in the lower pH range (pH 2–4) and from the catechol end at the higher pH range (pH > 5). The visible spectrum of Cu-A-dopa is similar to that of Cu-A-phenylalanine or Cu-A-tyrosine over the entire pH range, confirming amino carboxylate coordination. Δ log K (K_MAL - log_KML) is found to be positive in all the six Cu(II) complexes. whereas it is negative in Ni(II) complexes. Release in the ternary complexes of the repulsion between the Cu(II) dπ electron and electrons delocalized over the phenyl ring has been proposed as a probable reason for the positive Δ log K.     

The combined effects of temperature,salinity, and declining oxygen tension on oxygen consumption in the marine pulmonate Amphibola crenata (Gmelin, 1791)

Oxygen consumption of Amphibola crenata (Gmelin) was measured in various salinity-temperature combinations (< 0.1‰ to 41‰ salinity and 5 to 30°C) in air, and following exposure to declining oxygen tensions. In all experimental conditions, respiration varied with the 0.44 power of the body weight (sd = 0.14). The aquatic rate was consistently higher than the aerial rate of oxygen consumption, although at 30 °C the two rates were similar. Oxygen consumption increased with temperature up to 25 °C in all salinities; the lowest values were recorded at temperatures below 10 °C and at 30 °C in the most dilute medium. At all exposure temperatures, the oxygen consumption of Amphibola decreased regularly with salinity down to 0.1 ‰, and following exposure to concentrated sea water (41‰). Salinity had the least effect at 15 °C which was the acclimation temperature. In general, all of the temperature coefficients (Q₁₀ values) were low, < 1.65. However, Q₁₀ values above 2.8 were recorded at a salinity of 17.8‰ between 10 and 15 °C. Oxygen consumption of all size classes of Amphibola was more temperature dependent in air than in water and small individuals show a greater difference between their aerial and aquatic rates than larger snails. The rates of oxygen consumption in declining oxygen tensions were expressed as fractions of the rates in air saturated sea water at each experimental salinity-temperature combination. The quadratic coefficient B₂ becomes increasingly more negative with both decreasing salinity and temperatures up to 20 °C. At higher temperatures (25 and 30 °C) the response is reversed such that O₂ uptake in snails becomes increasingly independent of declining oxygen tensions at higher salinities. On exposure to a salinity of 4‰, Amphibola showed no systematic response to declining oxygen tension with respect to temperature. The ability of Amphibola to maintain its rate of oxygen consumption in a wide range of environmental conditions is discussed in relation to its potential for invading terrestrial habitats and its widespread distribution on New Zealand's intertidal mudflats.     

Growth, maturation and photosynthesis of the brackish water alga Rhizoclonium sp. (Cladophoraceae, Chlorophyta) in relation to salinity

The effects of salinity on growth, maturation and photosynthesis were examined in the filamentous alga Rhizoclonium sp. (Cladophoraceae, Chlorophyta) growing in a brackish water habitat in a canal draining into Tokyo Bay, Japan. In this habitat Rhizoclonium sp. was exposed to a wide salinity range, both daily, 5–23‰ during November 1996, and hourly, 6–24‰ during the spring tide day. From the results of culture experiments, growth and maturation of Rhizoclonium sp. occurred in the wide salinity range of 10–40‰ at 20 μmol photons m‐²s‐¹ at 20°C, but did not occur at salinity of 0‰. Light saturation on the photosynthesis‐irradiance curve at 20°C at 20‰ was reached at 100 μmol photons m‐²s‐¹, which is characteristic for shade‐adapted algae. On the photosynthesis‐salinity curve at 20°C at saturated irradiance (160 μmol photons m‐²s‐¹), the net photosynthetic rate increased with increasing salinity up to 30‰ but decreased at 40‰. On the photosynthesis–salinity curve at 20°C at 20 μmol photons m‐²s‐¹ (at near in situ irradiance), the photosynthetic rates were almost the same in the salinity range from 0 to 40‰. Therefore, this species is able to grow, reproduce and photosynthesize with a relative efficiency in a wide salinity range, which shows that it is well adapted to a brackish water environment.     

Identification, phylogenetic analysis and characterization of obligate halophilic fungi isolated from a man-made solar saltern in Phetchaburi province, Thailand

A total of 17 species from 43 isolates were obtained through serial dilutions of soil samples isolated from one of the man-made solar salterns located in Ban Laem district of Phetchaburi province, Thailand. Soil analysis of the sample revealed high salinity and moisture content, slight alkalinity and low amounts of nitrogen, total organic carbon and organic matter in the habitat. Morphological analysis was performed on all isolates, and molecular identification and phylogenetic analysis were carried out only on the halophilic fungi isolated. Six halophilic fungi, belonging to four species, were identified among the isolates, including five strains of Aspergillus genus [Aspergillus flavus, A. gracilis, A. penicillioides (2 strains) and A. restrictus]. One species was found to be a yeast, namely, Sterigmatomyces halophilus, which was the most frequent isolate found among the halophilic fungi. All other isolates were halotolerant fungi. Characterization of the halophilic fungal isolates showed that they were best adapted to conditions of 10–15 % NaCl (w/v), slight alkalinity (pH 7.0–7.5) and a temperature range of 30–35 °C.     

Responses of Embryos and Larvae of the Starfish <Emphasis Type="Italic">Asterias amurensis</Emphasis> to Changes in Temperature and Salinity

We studied the effects of different combinations of temperature (5, 10, 14, 17, 20, and 22°C) and salinity (from 32 to 8‰) on the development of the starfish Asterias amurensis Lutken from Vostok Bay, Sea of Japan. Embryonic development is the most vulnerable stage; it passes successfully at 10–17°C and the salinity range of 32 to 26‰. Blastulae are the most tolerant of changing environmental factors. They survive and develop at the temperatures of 5–17°C and in the salinity range of 32–18‰. Gastrulae and bipinnariae survive under higher temperature values and salinity from 32 to 20‰. The tolerance for decreased salinity during the process of fertilization and in the latest stage of development, the brachiolaria with the developing juvenile starfish, was confined to the salinity range of 32–22‰, which agrees with the tolerance of adult starfish Asterias amurensis. Thus, for normal development of the Amur starfish in the early stages, some particular conditions of temperature and salinity are required. This is, probably, due to adaptive capabilities of each developmental stage and the peculiarities of the ecological conditions at particular depths.     

A physico-chemical survey of inland lakes and saline ponds: Christmas Island (Kiritimati) and Washington (Teraina) Islands, Republic of Kiribati

Background

This study investigates the relationship between salinity and biotic communities (primary producers and macroinvertebrates) in Rambla Salada, a Mediterranean hypersaline stream in SE Spain. Since the 1980's, the mean salinity of the stream has fallen from about 100 g L^-1 to 35.5 g L^-1, due to intensive irrigated agriculture in the watershed. Furthermore, large dilutions occur occasionally when the water irrigation channel suffers cracks.

Results

Along the salinity gradient studied (3.5 – 76.4 g L^-1) Cladophora glomerata and Ruppia maritima biomass decreased with increasing salinity, while the biomass of epipelic algae increased. Diptera and Coleoptera species dominated the community both in disturbed as in re-established conditions. Most macroinvertebrates species found in Rambla Salada stream are euryhaline species with a broad range of salinity tolerance. Eight of them were recorded in natural hypersaline conditions (~100 g L^-1) prior to important change in land use of the watershed: Ephydra flavipes, Stratyomis longicornis, Nebrioporus ceresyi, N. baeticus, Berosus hispanicus, Enochrus falcarius, Ochthebius cuprescens and Sigara selecta. However, other species recorded in the past, such as Ochthebius glaber, O. notabilis and Enochrus politus, were restricted to a hypersaline source or absent from Rambla Salada. The dilution of salinity to 3.5 – 6.8 gL^-1 allowed the colonization of species with low salininty tolerance, such as Melanopsis praemorsa, Anax sp., Simulidae, Ceratopogonidae and Tanypodinae. The abundance of Ephydra flavipes and Ochthebius corrugatus showed a positive significant response to salinity, while Anax sp., Simulidae, S. selecta, N. ceresyi, N. baeticus, and B. hispanicus showed significant negative correlations. The number of total macroinvertebrate taxa, Diptera and Coleoptera species, number of families, Margalef's index and Shannon's diversity index decreased with increasing salinity. However, the rest of community parameters, such as the abundance of individuals, evenness and Simpson's index, showed no significant response to changes in salinity. Classification and ordination analysis revealed major differences in macroinvertebrate community structure between hypersaline conditions (76.4 g L^-1) and the rest of the communities observed at the lower salinity levels, and revealed that below ~75 g L^-1, dissimilarities in the communities were greater between the two habitats studied (runs and pools) than between salinity levels.

Conclusion

Salinity was the first factor determining community composition and structure in Rambla Salada stream followed by the type of habitat.