Tolerance of seahorse Hippocampus kuda (Bleeker) juveniles to various salinities

In line with current conservation efforts, some success in the captive breeding of the seahorse Hippocampus kuda (Teleostei: Syngnathidae) has been achieved. To evaluate the salinity tolerance of these hatchery‐bred juveniles, 9‐week‐old H. kuda were transferred without prior acclimatization from ambient full strength seawater (32–33 ppt) to salinities ranging from freshwater to 85 ppt. Survival, growth, and total body water content were determined after 4 and 18 days of exposure. Juvenile H. kuda are able to survive in dilute seawater (15 ppt) for at least 18 days without any compromise in growth (both wet and dry body weight), survival, and total body water. Fish abruptly transferred to freshwater succumbed within 4–24 h, while survival of 5 ppt‐reared fish decreased to ca. 65% in 18 days. Although 10 ppt‐reared seahorses had growth and survival comparable with the control (30 ppt seawater), total body water was significantly elevated indicating reduced adaptability. The upper limit of H. kuda salinity tolerance was 50 ppt. Fish reared at salinities ≥55 ppt succumbed within 24 h. Like several other marine teleosts, growth and survival of juvenile H. kuda tended to peak in diluted seawater salinities of 15 and 20 ppt. These results indicate the possibility of growing hatchery‐bred H. kuda in brackishwater environments.     

Effects of salinity on growth and survival of African sharptooth catfish (clarias gariepinus) larvae

Growth and survival of replicate batches of African sharptooth catfish (Clarias gariepinus) larvae were monitored in 0, 2.5, 5.0, 7.5 and 10 ppt salinity. No significant differences in mortality or growth rate were evident between 0 and 5 ppt salinity. At 7.5 ppt mortality rate was higher and larval growth rate declined in comparison to the lower salinities. At 10 ppt all larvae died within 48 hours. The condition factor of the larvae similar between 0–2.5 ppt and displayed a declining trend between 2.5–7.5 ppt. Osmoconcentratkm of blood plasma of C. gariepinus in fresh water was 280 ± 20 mOsm/kg which is equivalent to 9.5 ppt salinity. It was concluded that 0–2.5 ppt is the optimal sclinity range for larval rearing and that short-term exposure to higher salinities (2.5–7.5 ppt) could be effective in the treatment of ectoparasitic diseases.     

The salinity tolerance of the invasive golden apple snail (Pomacea canaliculata)

We exposed snails of an invasive species of golden apple snail (Pomacea canaliculata) to five artificial sea water treatments at salinity levels of 0, 5, 10, 15 or 20 parts per thousand (ppt) to assess their salinity tolerance. We observed the behaviour, heart rate, total haemocyte counts, haemolymph ionic concentration and Na⁺/K⁺-ATPase activity in the mantle at 0, 12, 24, 48, 72 and 96 h post salinity exposures. The heart rate declined with increasing salinity, while Na⁺/K⁺-ATPase activity in the mantle presented a reverse trend, possibly to maintain normal osmolality. A trend of rising total haemocyte count was observed from 0 ppt and 5 ppt to 10 ppt salinities, while a sudden increase in the count was observed at 15 ppt and 20 ppt salinity groups. Furthermore, haemolymph Cl^?, Na⁺ and K⁺ concentrations increased directly with elevated salinity. An additional trial was performed to assess the growth performance of the snails under exposure to low salinities. During a 1 month trial, snails grew better at 5 ppt salinity treatment. Taken together, our results demonstrate that P. canaliculata can tolerate salt stress to some extent. The finding also obviously implies a possible invasive risk to estuaries.     

Salinity tolerance and osmoregulation of the arctic marine amphipods Onisimus litoralis (Kroyer) and Anonyx nugax (Phipps)

Summary The gammarid amphipod Onisimus litoralis, which inhabits arctic and subarctic intertidal and under-ice habitats, is a euryhaline hyperosmotic regulator. It survives 10 d exposures to salinities from 5 to 55 ppt. It hyperregulates its hemolymph osmolality during 3 h exposures to dilutions of 33 ppt seawater and remains hyperosmotic for at least 2 w. The hemolymph is isosmotic to the medium after 12 h exposures to salinities higher than 33 ppt. The gammarid amphipod Anonyx nugax, which inhabits arctic and subarctic subtidal areas, tolerates salinities from 23 to 45 ppt with little mortality. Unlike Onisimus, however, it is an osmoconformer and its hemolymph becomes isosmotic to all dilute salinities within its tolerance range after 12 h and to concentrated media after 3 h. The salinity tolerances and osmoregulatory abilities of both species are reflected in their distributions in the field.     

Spectral reflectance of Thalassia testudinum (Hydrocharitaceae) seagrass: low salinity effects

Massive anthropogenic changes in estuarine salinities, from manipulations of freshwater flows, are again occurring through governmental projects “correcting” past freshwater alterations. The downstream effects of increased freshwater on seagrass meadows, a major fisheries and ecosystem habitat, are not clear. Spectral responses to low salinities were quantitatively delimited for the important habitat seagrass Thalassia testudinum utilizing spectral reflectance measurements for the first time (non-invasive sampling). Over a range of salinities (32–16 parts per thousand sea salts [ppt] for 24 h) and spectra (308–1138 nm), Thalassia specimens showed statistically significant differences in spectral values (P < 0.05) between treatments at normal (32 ppt) and 50% reduced (16 ppt) seawater. Mature blades yellowed at low salinities. Reflectance changes at 525 nm and 650–680 nm at low salinities suggested changes in xanthophylls and chlorophylls. Four indices were also used to characterize the reflectance spectra to delineate the effect of the salinity changes: (1) The normalized difference vegetation index (NDVI) for mature blades reduced at 16 ppt from that at 32 ppt. (2) The chlorophyll normalized difference index (Chl NDI) suggested chlorophyll content decreases in response to reduced salinity. (3) The structure independent pigment index (SIPI), higher in mature blades at 16 ppt than new blades, indicates a higher carotenoid : chlorophyll ratio in mature blades. (4) The photochemical reflectance index (PRI) suggested a lower photochemical efficiency at lower salinities. The main low-salinity effect on Thalassia physiology delineated herein is likely through changes in pigmentation (decreases in chlorophyll and changes in xanthophyll cycle epoxidation).     

Toxic effects of mercury on the hard clam,Meretrix lusoria,in various salinities

1. The 96-hr lc₅₀ values for juvenile hard clams, Meretrix lusoria, were 328, 392 and 194 μg/l Hg in 10, 20 and 30 ppt salinities at 25 ± 1°C, respectively; for adult hard clams 341 and 140 μg/l Hg in 20 and 30 ppt salinities, respectively.2. Acclimatizing the adult clams to low salinity of 10 ppt lessened the toxicity of mercury. However, juvenile animals appeared to be more sensitive to mercury poisoning after 96 hr exposure in 10 ppt salinity.3. All embryos exposed to 40 μg/l Hg and above died within 30 hr. In the control, 44% of hatched embryos had developed into D-stage larvae, while those exposed to 20 μg/l Hg were still in the trochophore stage. Most of the retarded larvae developed into abnormal forms within 30 hr at 28°C in 15 ppt salinity.4. In order to maintain water quality and protect natural resources, the recommended safe level of mercury is 0.046 (0.039–0.053) μg/l Hg, based on the estimated 30-hr EC₅₀ for the clam embryos, with an application factor of 0.01.     

Salinity tolerance in different life history stages of an invasive false mussel Mytilopsis sallei Recluz, 1849: implications for its restricted distribution

ABSTRACT

Although the false mussel Mytilopsis sallei Recluz, 1849 is recognised as an aggressive invasive species, its populations in several estuaries in Thailand are restricted to small areas. A salinity gradient is a major characteristic of its habitat, hence the effect of various salinity levels (0–40?ppt) on the mortality of larvae, juveniles and adults of M. sallei was investigated. Condition Indices of adults reared at different salinity levels for two months were measured. Spatial and temporal variations of salinity and false mussel abundance in a canal with a salinity gradient were also monitored. After an acute (48?h) test, survival of larvae was highest at salinity levels of 12.5 and 16.25?ppt and decreased at lower and higher levels. Juveniles survived at all salinity levels, but most adults died in the first 24?h at a salinity of 40?ppt, while condition indices were lowest at salinity levels of 30 and 35?ppt. In the field survey, highest false mussel abundance was consistently found at the middle part of the canal with mid-range salinity. The results suggested that salinity is a determinant of survival in M. sallei larvae and potentially regulates the dispersal success of false mussels. However, the importance of salinity was marginal in the later stages of its life history.     

Acute osmotic tolerance of cultured cells of the oyster pathogen Perkinsus marinus (Apicomplexa : Perkinsida)

Cultured Perkinsus marinus cells were exposed for 24 hr to salinities of 0, 3, 6, 9, 12 and 22 ppt at temperatures of 1, 5, 10, 15 and 28°C in artificial seawater (ASW) and to the same salinities at 28°C in ASW with the osmotic concentration adjusted with sucrose to the equivalent of 22 ppt. At 28°C mortality increased as salinity decreased below 22 ppt. Mortality was greater than 99% at 0 ppt and greater than 90% at 3 ppt. Mortality was 70% at 6 ppt, 43% at 9 ppt and 20% at 12 ppt. Mortality was low (<5%) and equal to that at 22 ppt in all treatments where osmotic concentration was maintained with sucrose. Mortality occurred rapidly, within 5 min of exposure to experimental conditions. In the region where mortality was most sensitive to salinity changes (6–12 ppt), lower temperature caused an increase in mortality, but the temperature effect was significant only at 9 ppt.     

Cloning and Expression of Four Aquaporin Homologs from the Chinese Black Sleeper (Bostrychus sinensis): The Effects of Salinity Acclimation

Several fish species are known to possess mechanisms that allow them to adapt to environments with different salinities. The aim of this study was to investigate the effects of salinity on the expression of aquaporins (aqp1a, aqp3a, aqp8a, and aqp9a) in the gills and intestines of Chinese black sleeper. After 30 days of acclimation, the expression of aqp1a, aqp3a, and aqp9a in the gills was significantly higher in fish transferred to 5 ppt than in those transferred to 40 ppt seawater, whereas aqp8 expression was lower. In contrast, aqp1a, aqp3a, and aqp8a expression in the intestines was higher in fish acclimated in 40 ppt than in those acclimated in 5 ppt. During abrupt salinity acclimation, the levels of aqp1a and aqp9a in the gills varied over time in fish acclimated in 5 ppt, but not in 40 ppt. The aqp3a levels in gills were higher in the 5 ppt group after 24 h than in the 40 ppt. The expression level of aqp8a in gills was higher in 40 ppt than in 5 ppt, except for that at 12 h. In the intestines, expression level of aqp1a and aqp8a were significantly upregulated from 12 to 48 h following acclimation in 40 ppt and aqp3a was higher in 40 ppt group than in 5 ppt, while aqp9a expression exhibited an opposite trend. These findings suggest that aqp1a, aqp3a, aqp8a and aqp9a may play a major osmoregulatory role in water transport in the gills and intestines during acclimation to different salinity environment.

     

A study of the relative efficiency of mustard oil cake and urea and the effect of salinity in plankton production in indian fishponds

Augmentation of plankton production in Indian fishponds by application of manure and inorganic fertilisers was studied in laboratory experiments. The effects of the salinity of the medium were also examined.Laboratory trials were made with mustard oil cake and urea on equivalent nutrient bases in media with varying degrees of salinity (0–30 ppt at 2 ppt. intervals). It was observed that Closterium, Fragilaria, Pinnularia and Gyrosigma grew well in the higher salinity range between 24 to 30 ppt. whereas lower salinities ranging from a trace to 8 ppt. are suitable for improved production of Anabaena, Synedra, Navicula, Amphipleura, Amphora and Nitzschia. Comparatively better production of plankton was recorded with urea than with mustard oil cake.     

Osmoregulation by the broad-snouted caiman, Caiman latirostris, in estuarine habitat in southern Brazil

The broad-snouted caiman Caiman latirostris, of South America mostly frequents freshwater but occurs also in estuaries. Nothing of substance is known of its osmoregulatory physiology but, in the light of accumulating evidence that alligatorids lack specialised adaptations for life in hyperosmotic waters, we anticipated its physiology would be more similar to that of Alligator mississippiensis than the euryhaline Crocodylus porosus, which has both lingual salt glands and a more complex renal:cloacal system. This proved to be the case. Caiman captured in estuaries of the Ilha do Cardoso in southern Brazil were effective hypo-osmotic osmoregulators in salinities of 0–24 ppt (seawater = 35 ppt). Plasma osmolarity, sodium and chloride were similar to those in other crocodilians and not influenced by salinity. Plasma urea was low and did not vary with salinity. We found no evidence of lingual or other salt glands. Urinary electrolyte concentrations varied considerably with salinity and in ways reminiscent of A. mississippiensis but very different from C. porosus. Ca. latirostris dehydrated in seawater more rapidly than C. porosus and had substantially higher integumental permeability to water. Caiman did not drink seawater but rehydrated rapidly when returned to freshwater (FW). We found small caiman (<500 g) only in very low salinities (<3 ppt) and larger caiman closer to the sea. We postulate that medium to large Ca. latirostris can take advantage of the feeding opportunities presented by the estuarine mangal despite lacking the physiological specialisations of crocodylids. Two individuals which we re-sighted by chance had travelled at least 600 m in 2–3 days, showing that every caiman we captured or saw was within easy reach of FW. Most likely their habitation of the estuary and its mangal is achieved through a combination of low surface area:volume ratio, relatively impermeable skin, and periodic access to FW. Accepted: 11 May 1998     

Salinity tolerance and osmotic regulation in the diamond killifish,Adinia xenica

Synopsis Salinity tolerances and plasma osmotic regulatory capacity were determined in individuals of Adinia xenica following laboratory acclimations. Survival of individuals was better than 90% of those entered into the acclimation sequence from an initial acclimation salinity of 17.0 ppt down to fresh-water, and up to 95.0 ppt. Survival of individuals transferred from 95.0 to 105.0 ppt was low. Adinia showed most consistent plasma osmotic regulation in the range of ambient salinities from 17.0 to 60.0 ppt, but responded well over the ambient salinity range from 0.5 ppt to 85.0 ppt. Plasma osmotic concentrations were higher at common ambient salinities, but in a generally similar overall pattern of response, compared with such euryhaline cyprinodontids as Cyprinodon variegatus and Fundulus kansae.     

The effect of cadmium on plasma melanocyte-stimulating hormone and morphological changes of melanophores in the cichlid fish Oreochromis niloticus,at different salinity levels

ABSTRACT

The effects of cadmium concentration (0, 2.5 and 5 mg L^?1) on melanocyte-stimulating hormone (MSH), melanophore index (MI), and melanophore number (MN), as well as a microscopic examination of scale melanocytes in tilapia (Oreochromis niloticus Linnaeus, 1757) was evaluated at different salinity levels (0, 5 and 15 ppt). The levels of MSH, MI, and MN were lower in Cd-exposed fish than in control fish (not exposed to Cd) at salinity level of 0 and 5 ppt. In ppt, however these levels of MSH, MI and MN in control and Cd-exposed fish were not significantly different. In the media without Cd, the levels of MSH, MI and MN were not significantly different at all salinities. The morphological changes of melanophores were higher in Cd-exposed fish than in control fish at salinity 0 and 5 ppt, respectively. These morphological changes were not significantly different in the control fish at all salinities as well as in fish exposed to 0–5 mg L^?1 Cd at salinity of 15 ppt. This study therefore demonstrates that the toxic effect of Cd on MSH levels and melanophore morphology decreased with increasing salinity. Further, due to the sensitivity of chromatophores to Cd, melanophore morphology is proposed as a biomarker of Cd exposure in aquatic ecosystems.     

Lead toxicity at different life stages of the giant prawn (Macrobrachium rosenbergii,de Man): considerations of osmoregulatory capacity and histological changes in adult gills

This study evaluated the acute toxicity of lead in different life stages of the freshwater prawn Macrobrachium rosenbergii, determined the effect of sublethal Pb concentrations on osmoregulatory capacity (OC), measured the Pb level in gills, and investigated the effect of Pb on the structure of the gills of adult prawns. The 24-, 48-, and 96-h LC₅₀ values for Pb to M. rosenbergii increased progressively with increasing life stage, from post-larvae (PL), juvenile to adult. The 24- and 48-h LC₅₀ values for post-larvae ranged from 0.01- to 0.09-mg Pb/L. The 24-, 48-, and 96-h LC₅₀ values for Pb were lower at 12 ppt than those at 0 ppt for either the juveniles or the adults. At 12 ppt, the 96-h LC₅₀ values in PL11, juvenile and adult were 0.47-, 0.58-, and 2.03-mg Pb/L, respectively. Meanwhile, at 12 ppt, the 96-h LC₅₀ values in PL11, juvenile and adult were 0.63-, 4.44-, and 7.98-mg Pb/L, respectively. In adults, the OC values of controls and prawns exposed to 2- and 4-mg Pb/L at 0 ppt were not significantly different. The OC of prawns exposed to and 2-mg Pb/L at 12 ppt increased by 72 and 109% from the OC of the control prawns. At media 12 ppt, the OC value of prawns exposed to 1-mg Pb/L was significantly different from that of prawns exposed to 2-mg Pb/L. The concentrations of Pb in gill tissues increased significantly in Pb exposed prawns both at 0 and 12 ppt. The level of Pb in gills of prawns exposed to 2-mg Pb/L at 12 ppt was not significantly different from those exposed at 0 ppt. The severe toxic actions of Pb were noted in gills of prawns exposed in media 12 ppt. Hyperplasia and necrosis were observed in gill lamellae, resulting in abnormal gill tips after Pb exposure at media 12 ppt. Since the effect of Pb is more pronounced in higher salinity (12 ppt) than in freshwater (0 ppt) it is clear that aquaculture of M. rosenbergii should be conducted in freshwater ponds.     

Salinity‐induced changes to the survival,growth and glycogen distribution in the early fry stages of silver barb,Barbodes gonionotus (Bleeker, 1850)

Five‐week‐old silver barb, Barbodes gonionotus, fry (initial length = 10 mm) were subjected to different salinities of 0, 3, 6 or 9 ppt for 17 days, to then assess their survival and growth. Whole body histological sections were stained with Periodic‐acid Schiff (PAS). Groups of 15 fish were triplicated in each treatment with an ambient temperature (26–28°C). Results showed that growth and condition factor significantly decreased and increased (p < .05), respectively, with the increased salinities after 17 days. While survival was similar (p > .05), between 0 and 6 ppt (at 98% and 87%, respectively), the decrease was significant at 9 ppt (22%). In addition, the fry at 9 ppt had fewer gill mucous cells as well as reduced PAS positive staining intensity within the liver and intestine. This suggests energy was becoming exhausted, leading to mortalities and lower growth. Silver barb early fry were relatively sensitive to elevated salinity, which was likely due to their young age, but short‐term exposure to 3–6 ppt can be used to decrease potential freshwater diseases in the early nursery culture.     

Microcosm analysis of salinity effects on coastal lagoon plankton assemblages

A microcosm experiment was conducted to assess the effects of salinity on coastal lagoon plankton assemblages. Five salinity levels were replicated four-fold in 3801 fiberglass tanks. Salinity levels used were 0, 8.5, 17, 34 and 51 ppt, or 0, 25, 50, 100 and 150 percent seawater. These were achieved by mixing concentrated lagoon water and tapwater in different proportions. Tanks were inoculated with plankton collected from San Dieguito Lagoon (Del Mar, San Diego County, California) and other fresh and saline waterbodies in the area. Selected physical-chemical variables, phytoplankton, zooplankton, and other invertebrate populations were monitored on five sampling dates over a 114 day period (13 August–5 December 1986).Total phytoplankton abundance increased with salinity, for salinities >17 ppt. Most taxa showed marked effects of salinity, though the pattern of the effects often varied greatly from date to date. Chlorophytes tended to be most abundant at 51 ppt. Pyrrhophytes were most abundant at 0 or 51 ppt, and least abundant at 8.5 or 17 ppt. Cryptophytes increased with increasing salinity. Euglenophytes exhibited no salinity effect on any date. Bacillariophytes were most abundant at 8.5–34 ppt and least abundant at 51 ppt, with individual taxa showing maxima at 0–17 ppt (Navicula, Synedra), 8.5–34 ppt (Surirella, Amphora), and 34 ppt (Cylindrotheca).Total zooplankton abundance decreased with salinity, for salinities > 17 ppt. The dominant taxa were protozoans, rotifers, cladocerans, and copepods, and all but the first group showed strong salinity effects. Protozoan abundance was unaffected by salinity. Rotifers were most abundant at 0 ppt (Keratella, Filinia) or 8.5 ppt (Brachionus). With few exceptions, cladocerans (Alona, Ceriodaphnia, Scapholeberis) were found only at 0 ppt. Abundance of calanoid copepods decreased with increasing salinity, with individual taxa showing maxima at 0 ppt (Diaptomus), 8.5–17 ppt (Pseudodiaptomus, Eurytemora), and 34 ppt (Acartia). Cyclopoid copepods were most abundant at 17 ppt, with individual taxa showing maxima at 0 ppt (Eucyclops), 8.5 ppt (Halicyclops), and 17 ppt (Oithona). Harpacticoid copepods (Cletocamptus, Tachidius) were most abundant at 17–34 ppt. Ostracods and mosquito (Culex) larvae were most abundant at 8.5 ppt and absent at 34 and 51 ppt. Polychaetes generally were most abundant at 17–34 ppt, and water boatmen (Trichocorixa) at 8.5–34 ppt. Various physical and chemical variables also showed significant variations with salinity. Tending to increase with salinity were temperature, ammonia and orthophosphate concentrations. Decreasing with salinity were pH, dissolved oxygen and silica concentrations. The causes and interrelationships of these salinity effects are discussed.     

Salinity Tolerance in Some Selected Aquatic Oligochaetes

Salt tolerance of the freshwater tubificid Limnodrilus hoffmeisteri varied from an LD 50 of 10 ppt to 10.5 ppt for mature and immature worms without sediment, 9.4 to 10.5 in sand, and 14.3 for immatures acclimated to 5 ppt. Ilyodrilus templetoni was similarly intolerant to higher salinities. The estuarine Tubificoides gabriellae tolerated salt water, but was susceptible to freshwater, with LD 50's of 2 and 3.5 when acclimated to 5 and 10 ppt sea water. It survived immersion in freshwater for 3 hours. The estuarine naidids Paranais litoralis and frici experienced mortalities at both high and low salinities but showed a wide tolerance range. The coastal tubificid Monopylephorus irroratus showed almost complete tolerance to the salinity range employed. The findings reflected field distributions especially when interstitial salinities were measured, but worms did not occupy the full range of habitats possible in terms of salinity alone.     

Growth and physiological parameters of whiting (Sillaginodes punctata) in relation to salinity

This study assessed the impact of salinity on whiting (Sillaginodes punctata) in an attempt to understand the mechanisms by which salinity could potentially influence habitat selection and growth of King George whiting in southern Australia. The experiment included whiting of two age classes, young of the year (YOY) and 2⁺ year, at three salinities (30, 40, 50 ppt). YOY whiting showed no significant difference in length or weight gain, specific growth rate, feed intake, food conversion ratio or condition factor when exposed to the three salinities for 72 day. Plasma osmolality of YOY whiting was not significantly different at any salinity, although it was significantly lower than that of 2⁺ year whiting. The 2⁺ year whiting showed significantly higher plasma osmolality than the YOY. Blood plasma potassium and chloride levels of 2⁺ year fish at 50 ppt were significantly higher than those at 30 ppt and 40 ppt. Blood sodium levels at 50 ppt were significantly higher than at 30 ppt but the sodium level at 40 ppt was not different from 30 ppt or 50 ppt. Haematocrit of 2⁺ whiting was significantly higher at 30 than at 50 ppt while haematocrit at 40 ppt was not different from 30 or 50 ppt. The 2⁺ year‐old whiting had a more pronounced increase in plasma osmolality and plasma ions at high salinities, indicating poorer osmoregulatory capacity in older fish. This study provides physiological evidence to partially explain habitat occupancy and growth in relation to salinity of different age groups of whiting in southern Australia.     

Acclimation trials of wild and hatchery sea bass (Dicentrarchus labrax) fry at different salinities

Hatche and wild sea bass (Dicentrarchus labrax) fry were transferred from sea water to low salinities and freshwater (FW) usiny three different operational protocols: 1) direct exposure to ow salimues and FW (LC 50 test, ST 50 test); 2) quick acclimation to FW (48h); 3) slow acclimation to FW (17d). Direct exposure to freshwater led to e death of all fry. Comete survival was observed after direct transfer to salinities ≥ 9 ppt, both in wild and hatchery fry. Eatchery fry tolerate direct transfer to low salinities (LC 50=4.393 ppt) better than wild fry (LC 50 = 3.215 ppt). Slow acclimation rotocol leads to higher survival rates (nearly 90 %) than does the quick procedure. In 48h and 17d accimation trials wild fry tolerate FW better tlan hatchery fry. Hypotheses to explain observed differences in wild and hatchery tolerances to low salinities and FW are discussed.     

Influences of Salinity on Growth and Survival of Juvenile Pinfish <Emphasis Type="Italic">Lagodon rhomboides</Emphasis> (Linnaeus)

We investigated the effect of salinity on growth, survival, and condition of pinfish Lagodon rhomboides juveniles (36–80 mm standard length) in two laboratory experiments in July 2003 and June/July 2004. Our results show that juvenile pinfish grown in laboratory conditions under a range of salinities experience rapid growth and high survival in typical estuarine-like salinities (15–30 ppt). We also found that relative weight as an index of condition corroborates the idea that pinfish are well adapted to survive and grow in a wide range of salinities. Such rapid growth and high survival in a dynamic environment may afford juvenile pinfish potential ecological advantages over other estuarine-dependent fish species that are relatively more constrained by changes in salinity regime. Because coastal development is wide-spread throughout Gulf of Mexico and Atlantic estuaries, insights concerning the impacts of human-induced changes to estuarine environments are essential for effective management practices.