Effect of salinity on survival, growth and biochemical parameters in juvenile Lebranch mullet Mugil liza (Perciformes: Mugilidae)

Abstract

Teleost fish growth may be improved under isosmotic condition. Growth and metabolic performance of juvenile Mugil liza (isosmotic point: 12‰) were evaluated after 40 days in different salinities (0, 6, 12 and 24‰). Tests were performed in quadruplicate (30 fish/tank; 0.48 ± 0.1 g body weight; 3.27 ± 0.1 cm total length) under controlled water temperature (28.2 ± 0.1°C) and oxygen content (>90% saturation). Fish were fed on artificial diet (50% crude protein) four times a day until apparent satiation. Results showed that salinity influenced juvenile mullet growth. Fish reared at salinity 24‰ grew better than those maintained in freshwater (salinity 0‰). Gill Na + ,K + -ATPase activity and whole body oxygen consumption showed an U-shape-type response over the range of salinities tested, with the lower values being observed at the intermediate salinities. Although no significant difference was observed in liver glycogen content at different salinities, it tended to augment with increasing salinity. These findings indicate that energy demand for osmorregulation in juvenile M. liza can be minimized under isosmotic condition. However, the amount of energy spared is not enough to improve fish growth. Results also suggest that M. liza is able to alternate between different energy-rich substrates during acclimation to environmental salinity.O crescimento de peixes teleósteos pode ser melhorado em condição isosmótica. O crescimento e o desempenho metabólico de juvenis da tainha Mugil liza (ponto isosmótico: salinidade de 12‰) foram avaliados após 40 dias de cultivo em diferentes salinidades (0, 6, 12 e 24‰). Os testes foram realizados em 4 réplicas (30 peixes/tanque; 0,48 ± 0,1 g de peso corporal; 3,27 ± 0,1 cm de comprimento total) em condições controladas de temperatura (28,2 ± 0,1°C) e conteúdo de oxigênio (>90% saturação). Os peixes foram alimentados quatro vezes ao dia com dieta artificial (50% de proteína bruta) até a saciedade aparente. Os resultados mostraram que a salinidade influenciou o crescimento dos juvenis da tainha. Os peixes cultivados na salinidade 24‰ cresceram melhor que aqueles mantidos na água doce (salinidade 0‰). A atividade da Na + ,K + -ATPase branquial e o consumo corporal de oxigênio mostraram uma resposta do tipo em forma de U, na faixa de salinidade testada, com os menores valores sendo observados nas salinidades intermediárias. Apesar de não ter sido observada diferença significativa no conteúdo de glicogênio entre os peixes mantidos nas diferentes salinidades, este parâmetro tendeu a aumentar com o incremento da salinidade. Estes achados indicam que a demanda energética para osmorregulação em juvenis de M. liza podem ser minimizados em condição isosmótica. Entretanto, a quantidade de energia poupada não é suficiente para melhorar o crescimento. Os resultados também sugerem que M. liza é capaz de alternar entre diferentes substratos ricos em energia durante a aclimatação à salinidade da água.

Acclimation of juvenile Mugil liza Valenciennes, 1836 (Mugiliformes: Mugilidae) to different environmental salinities

“…Also, it is important to note that juveniles of M. liza reared at 24‰ were shown to grow better than those maintained in fresh water for 40 days. However, fish reared at 12‰, which is very close to its isosmotic point (13.5‰), showed similar growth to those maintained at 0, 6 and 24‰ (Lisboa et al, 2015). Taken together, these findings clearly do not support the "Isosmotic Theory" for juveniles of the Lebranche mullet M. liza.…”

“…However, this theory seems to be species-specific, since it has been proved for some fish species like Sparus sarba (Woo & Kelly, 1995), but not for others like Paralichthys orbignyanus (Sampaio & Bianchini, 2002). Very recently, we have shown that juveniles of the Lebranche mullet M. liza reared at 12‰, a salinity close to the isosmotic point, did not display a better growth than those cultivated in a wide range of salinities (0-24‰) (Lisboa et al, 2015). Results from the present study are in agreement with this finding, thus suggesting that the idea of improving fish growth at isosmotic condition cannot be considered for juveniles of the Lebranche mullet M. liza.…”

“…Among abiotic factors, the influence of water salinity on fish growth has been reported for several species (Woo & Kelly, 1995;Sampaio & Bianchini, 2002;Resley et al, 2006), including the mullet Mugil liza Valenciennes, 1836 (Lisboa et al, 2015).…”

“…Fonseca /1999 reported no mortality after 96 h of abrupt transfer of juvenile M. liza from sea water (30‰) to lower salinities (15, 10 and 5‰). Very recently, we have shown that salinity influenced growth without significant changes in biochemical parameters (gill Na + /K + -ATPase and liver glycogen content) in juvenile Lebranch mullet M. liza after a 40-days rearing period in different salinities ranging from 0 to 24‰ (Lisboa et al, 2015).…”

PERTUMBUHAN DAN VARIASI GENETIK IKAN BANDENG, Chanos chanos DARI PROVINSI ACEH, BALI, DAN GORONTALO, INDONESIA

“…Kondisi tambak BBRBLPP Gondol di musim kemarau, saat salinitas tinggi sangat memengaruhi pertumbuhan yang berkaitan dengan perangsangan makan maupun osmoregulasi. Menurut Lisboa et al (2015), sebagian besar hewan laut tipe osmoregulator-eurihalin, pengaruh langsung dari salinitas media pemeliharaan adalah melalui efek osmotiknya, ikan hanya akan mempertahankan keseimbangan terhadap Gambar 1. Pertumbuhan panjang total ikan bandeng, Chanos chanos dari lokasi perairan Aceh, Bali, dan Gorontalo.…”