Temperature Tolerance and Metabolic Depression of a Convict Child Under the Influence of Enhanced Ultraviolet-A (320-400 nm) Irradiation

• Published in: Aquaculture international Vol. 7; no. 1; p. 13
• Main Authors: Winckler, Klaus, Fidhiany, Lucia
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Nature B.V 01.01.1999
• Subjects: Developmental stages; Fish; Fish populations; Hatching; Irradiation; Oxygen consumption; Temperature
• ISSN: 0967-6120; 1573-143X
• DOI: 10.1023/A:1009236618927

The effect of an enhanced (5%) sub-lethal UVA irradiation on the total metabolism of a sub- tropical convict cichlid (Cichlasoma nigrofasciatum) is described. The specific oxygen consumption (vo^sub 2^) of related but differently treated populations was determined from 23 °C to 35 °C, to detect their tolerance limits toward environmental temperature. The experiments cover two generations (G1 and G2) of inbred derived populations. The fish were measured at different stages of development covering the period before and after maturation. The fish were grown at and adapted to 27-29 °C. The results showed that the population which was grown under an enhanced UVA irradiation since hatching (G2-UVA) had developed a general metabolic depression (MD) at all ranges of experimental temperature. The MD was especially expressed after the fish reached maturation. No MD was shown for the non-irradiated control populations (G2-control and G1-control) nor for the mature fish of G1-UVA. The G1-UVA population was grown under an enhanced UVA irradiation from 4 months of age. The vo^sub 2^ increased with increasing temperature, reaching a maximum at 31-33 °C for the G1- and G2-control populations. For the G1-UVA, a small peak of vo^sub 2^ was obtained at 29 °C reaching its maximum level at 33 °C. For the G2-UVA population, a maximum vo^sub 2^ was reached at 33 °C for the young and mature fish and at 29 °C during the maturation period. It can be concluded that the accumulation of UVA irradiation from early life was responsible for the MD in this fish. A wider temperature tolerance observed in the G2-UVA population might possibly be due to a reduction of total metabolic activity. The mechanisms underlying the MD observed in this fish are not yet known, but natural selection and adaptation processes might be involved.[PUBLICATION ABSTRACT]