Salinity

1998

Recent interest in the culture of cold water marine fish has prompted many questions with regards to water quality during early culture. Although temperature is probably the most important parameter of water quality, another key factor in determining site locations as well as optimizing success is salinity. Since salinity may vary dramatically from one location (e.g. estuarine) to another (eg. open ocean), determination of the optimal salinity for a species is important in selecting site locations for prospective marine hatcheries. The current study investigated salinity effects in four prospective aquaculture species: winter flounder, haddock, cod, and halibut. -- Studies were undertaken to determine the optimal salinities for egg survival and their effects on the viability, size, and behaviour of newly-hatched larvae. Eggs from each species were incubated at salinities of 15, 20, 25, 30, and 35 ppt and a variety of parameters including hatch rate, % viable larvae, larval size, yol...

Aquaculture Research, 2008

We report the e¡ect of salinity and temperature on the viability of stored culture-based subitaneous eggs of the calanoid copepod Acartia tonsa for use of copepods in ¢sh larvae culture. Quiescence induction was recorded at 17 and 25 1C, in salinities from 0 to 30. Quiescence was strongly induced at 0 salinity and partially at 5 in both temperatures. Eggs incubated at 0 salinity for up to 12 days at both temperatures showed a decline in the fraction able to be induced into quiescence by abrupt salinity changes. The hatching success of eggs that were able to enter quiescence stabilized after a 1-day incubation and remained $ 25% viable for 12 days in 17 1C. On the contrary, the 25 1C trial showed a gradual decline in viability until stabilizing $ 10% at day 7 and onwards. Longterm 17 1C incubation for 35 days showed that eggs remained quiescent with a viability of $ 14%. Hence, we recommend salinity storage of A. tonsa subitaneous eggs as a relevant shortterm technique, and a suitable alternative to the recently proposed cold storage of eggs when eggs are to be shipped from the copepod producer to a given ¢sh larvae hatchery.

2005

"The shrimp Palaemonetes argentinus Nobili 1901 inhabits freshwater streams, lakes and brackish coastal lagoons in the warm temperate regions of southeastern South America. Larvae and adults tolerate a wide range of salinities, exhibiting a well developed osmoregulatory capacity already from hatching. Nevertheless, effects of salinity on the embryos of P. argentinus have not been studied yet. In the present investigation, freshly layed eggs were removed from ten females and, from the time of extrusion to larval hatching, exposed in vitro to four salinities (1, 15, 25, 32 PSU; all incubated at 20EC). This technique allowed the comparison of salinity effects on embryos of the same brood, excluding maternal effects as potentially confounding sources of variation. Initial egg size and duration of embryonic development under identical conditions varied significantly among broods from different females, but showed no significant relationships with female body size. Development was most successful in eggs incubated at salinities of 1 and 15 PSU, with average hatching rates of 72% and 79%, respectively. In contrast, 20% hatched at 25 PSU, and only three individuals (1.5%) in seawater (32 PSU). Egg mortality increased consistently near the end of the developmental period, especially at 25 and 32 PSU. Larvae hatching at these relatively high salinities retained a greater quantity of yolk, while many were deformed, suggesting that hyperosmotic stress interfered with metabolic energy mobilization and morphogenetic processes. The mean time from spawning of the eggs to larval hatching was similar at 1 and 15 PSU (ca. 24 d), but lasted significantly longer at 25 and 32 PSU (26–27 d, respectively). During the first ca. 10–12 days of embryonic development, the volume of the eggs decreased slightly at 25 and 32 PSU, while an increase was observed at lower salinities (maximum: 20% at 1 PSU). During the final period of development, an increase in egg volume occurred in all treatments, being significantly stronger at low salinities (#15 PSU). The first zoeal stage of P. argentinus can also in complete absence of food successfully develop from hatching through the moult to the zoea-II stage; this trait (facultative lecithotrophy) was not affected by salinity. Our results suggest that successful reproduction of P. argentinus in freshwater and brackish habitats with highly variable conditions of salinity and food availability is based on an early appearance of osmoregulatory functions during the embryonic phase and/or a low permeability for ions of the egg membrane, while yolk reserves persisting from the egg allow for food-independent development through the first larval stage.""

Marine Ecology Progress Series, 2010

Mass density, sinking speed and hatching success of eggs in Calanus euxinus, Acartia clausi and A. tonsa have been examined in response to salinity and temperature of the Marmara and Black Seas. Eggs of C. euxinus from the Marmara and Black Sea populations (mean mass density of 1.036 to 1.040 g cm -3 ) laid in brackish (18 to 22 psu) upper layers of the Marmara Sea could sink to high-saline (~38.5 psu) deep layers during embryonic development. Gradual salinity increase from 22 to 38.5 psu in laboratory experiments reduced egg hatching success in C. euxinus from the Marmara Sea from 97 ± 4 to 47 ± 11% (means ± SD) while all eggs of the Black Sea C. euxinus did not hatch. Mean mass density of eggs in A. tonsa and A. clausi amounted to 1.062 and 1.044 g cm -3 , respectively. Eggs of A. tonsa with higher mass density and longer development time than those of A. clausi could descend to high salinity strata in the Marmara Sea, or to a cold intermediate layer in the Black Sea. On the contrary, sinking depth of eggs of A. clausi should not exceed 30 m both in the Black and Marmara Seas, as this increases predator pressure. Hatching success in A. tonsa eggs laid at 18 psu decreased from 77.7 ± 18.5% at 20°C to 46.7 ± 21.5% at 7°C, and reduced to 10.2 ± 4.7% at 7°C and 39 psu. Egg hatching success in A. clausi from the Black Sea did not depend upon temperature, whilst it decreased dramatically from 80 to 90% to 3.3 to 10% after salinity increase from 18 to 38 psu.

2007

Aquaculture Research, 2019

Aquaculture, 2008

The tropical calanoid copepod, Acartia sinjiensis, has good potential for mass culture as a live feed for tropical reef fish larvae. This study was carried out to investigate the effects of temperature and salinity on population growth and egg hatching rates of A. sinjiensis. At a salinity of 30 ± 1 psu, temperature effects on population growth of A. sinjiensis was determined after 8 day culture at eight temperatures of 10, 15, 20, 25, 28, 30, 34 and 38°C. Adopting similar experimental protocols, effects of salinity on population growth of A. sinjiensis were investigated under nine salinities of 10, 15, 20, 25, 30, 35, 40, 45 and 50 psu, with culture temperature set at 30 ± 1°C. In addition to population growth experiments, egg hatching rates (%) after 48 h of incubation at various temperature and salinity conditions were also examined. For all experiments, five replicates were set up for each treatment. A. sinjiensis were fed an identical binary algal diet of Tetraselmis chuii and the Tahitian strain of Isochrysis sp. (T-ISO), photoperiod was maintained at 12 L:12D.

Journal of Experimental Marine Biology and Ecology, 2009

The brackish water copepod Eurytemora affinis is the most abundant copepod species in the low salinity zone (2-15) of the Seine estuary. Despite its ecological importance, little is known about its population dynamics in the Seine. We studied the effects of temperature (10 °C and 15 °C) and salinity (5, 15 and 25) on reproduction under non-limiting food conditions. We used experiments to determine multiple reproductive parameters for E. affinis. In all experiments, we fed E. affinis a mixture of Rhodomonas marina and Isochrysis galbana. Couples of pre-adult females (C5) and adult males were mated until the female extruded a clutch of eggs and then individual females were observed every 6-12 hours until death to determine (a) embryonic development time, (b) inter clutch time and (c) clutch size throughout their adult lifespan. All reproductive parameters were negatively affected by low temperature (10 °C) and by high salinity (25). At 10 °C and a salinity of 25, mortality during the post-embryonic period was extremely high (85%). Differences in all reproductive parameters between salinities 5 and 15 were minimal. From 15 °C to 10 °C mean latency time (time between hatching of eggs and extrusion of new ones) increased from 0.8 to 2.25 days, the mean embryonic development time from 2.2 to 3.2 days and the mean clutch size decreased from 38 to 22 eggs female- 1. The mean clutch size decreased when females reached a critical age. The hatching success was high (near 95%) under all conditions except at high salinity. Egg production rates showed no significant differences between salinities 5 and 15 and were significantly higher at 15 °C (13 eggs female- 1 day- 1 at salinity 5 and 15) than at 10 °C (4 eggs female- 1 day- 1). These values at 15 °C were higher compared to those from other populations of E. affinis in estuaries or lakes. The high reproductive potential of E. affinis from the Seine estuary at 15 °C and low salinities explain its high densities in the low salinity zone during spring and early summer.

Salinity is an important factor for fish embryonic development. In tilapias, tolerance to salinity at any age is influenced by physiological responses of each species and can be transferred into hybrids. We evaluated the differences with respect to hatching rate (HR), total length at hatching (TL) and yolk sac area (YS) in eggs obtained from breeders kept at 0‰ and directly transferred to salinities of 0, 5, 15, 25, 35, 45, 55 and 65 ‰, after egg collection of the following varieties of tilapia: red tilapia (Oreochromis sp) (RT), a hybrid 1 (H1) obtained from the cross of Nile tilapia (male) X red tilapia (female) and a new red synthetic tilapia as hybrid 2 (H2): Pargo-UNAM.

Turkish Journal of Zoology, 2012

Th e combined eff ects of 3 diff erent temperatures (24, 28, and 32 °C) and salinity levels (35, 40, and 45 g L-1) on the egg hatching rate, incubation time, larval activity, and survival rate until protozoal (PZ1) stage of Metapenaeus monoceros (Fabricius) were investigated under controlled laboratory conditions. Th e average fertilization rate was 97.25% following spawning. Th e eggs were stocked in 2-L glass larval culture fl asks and received 1 of 9 salinity and temperature combinations in 3 replicates. Th e eggs hatched in all treatments. Temperature, salinity, and their interaction had signifi cant infl uences on the hatching rate of the eggs (P < 0.05). Th e hatching rate decreased as salinity increased and was lowest in all temperature levels at a salinity of 45 g L-1. With regard to the hatching rate, the best combinations were obtained at 35 g L-1 and 32 °C (91.67%) and at 35 g L-1 and 28 °C (89.17%). Th e incubation time was shorter at 32 °C (11.2 h) than at 28 °C (14 h) or 24 °C (17.2 h). Th e development rate from the naupliar stage to the protozoal stage was best at a salinity level of 35 g L-1 combined with temperatures of 28 °C and 32 °C. Larval activity was also found to be best at 28 °C and 32 °C at 35 g L-1 and 40 g L-1 , as compared to that at 24 °C in all salinity levels.