Influence of Water Salinity on the Growth and Survivability of Asp Larvae Leuciscus aspius (Linnaeus, 1758) under Controlled Conditions

Abstract

The effect of water with a salinity 3, 5, 7, 9 and 11 ppt on the growth and survivability of asp Leuciscus aspius (L.) larvae was investigated. A control sample consisted of asp larvae reared up in freshwater (0 ppt). Larvae were fed for 21 days with nauplii of the brine shrimp Artemia salina. Water salinity was observed to have a considerable effect on the growth and survivability of asp larvae. In addition, saline water extended the life span of Artemia salina nauplii, which resulted in their prolonged availability to asp larvae. Asp larvae showed low tolerance to the salinity of water, reaching 9–11 ppt. Depending on the degree of salinity, the mean final weight of larvae varied from 122.6 to 139.4 mg, at body lengths from 23.8 to 25.6 mm, respectively. The best body length increments were recorded among asp larvae maintained in water with a salinity of 3 ppt. Depending on the level of water salinity, the final survivability of asp larvae ranged from 16.9 to 94.5%. The highest and increasing mortality was demonstrated among the larvae reared in water of the salinity equal to 11 ppt. It is not recommended to rear asp larvae in water with a salinity above 7 ppt due to the low survivability and large differences in the body size of the larvae that managed to survive.

Effect of Different Water Salinities on the Larvae of the Blue Bream Ballerus ballerus (Linnaeus, 1758) during Rearing

“…Point or sectional salinity is not without influence on the biocoenoses of local water bodies, including the resident ichthyofauna [ 1 , 10 , 13 ]. This study confirms that blue bream larvae, like asp larvae inhabiting similar environments, also tolerate waters with salinity levels of 3–7 ppt [ 28 ]. Older individuals of rheophilic cyprinid fish are able to tolerate much higher water salinities.…”

“…Current investigations in many research centres focus on determining the ability of various taxa to survive in water where salinity has occurred rather than on increasing the effects of rearing using saline water. The described experiment on blue bream larvae fits perfectly into this issue, as developing embryos and early-stage fish larvae, in addition to fish gametes, are particularly sensitive to changes in water salinity [ 13 , 14 , 15 , 16 , 28 , 45 , 46 ]. Freshwater fish are exposed to saline water not only when they are in the intertidal zone or when migrating from fresh to saline waters, but also while in their natural habitat.…”

“…Most of the studies have been on fish reared for consumption, in which the optimum salinity level to increase rearing efficiency in recirculating RAS systems has been determined [ 39 , 40 , 41 , 42 , 43 , 44 ]. Examples include studies on the rearing of larvae of sichel Pelecus cultratus [ 45 ] and asp Leuciscus aspius [ 28 ]. The above studies made it possible to raise more fish with less labour and energy.…”

“…The filter medium consisted of bactoballs used in denitrification filters (AB Aqua Medic GmbH, Bissendorf, Germany). The water circulation in each circuit and the water supply to the individual aquaria were identical to the methodology described by Kujawa and Piech when studying the effects of salinity on asp larvae ( Figure 1 ) [ 28 ].…”

“…They were caught in the morning (before feeding began). Fish were weighed to the nearest 0.1 milligram and measured to the nearest 0.1 mm [ 28 ].…”