The effect of dietary arachidonic acid on growth, survival, and cortisol levels in different-age gilthead seabream larvae (Sparus auratus) exposed to handling or daily salinity change

摘要

The effect of dietary arachidonic acid (ArA) on survival, growth, and cortisol level in different-age gilthead seabream larvae exposed to handling or daily fluctuating salinity was tested. Premetamorphosing (3-19 DPH) larvae were reared in 400-1 V-tanks and fed one of three rotifer treatments containing ArA levels of 1.14, 2.11, or 3.87 mg g(-1). At 20 DPH, the larvae were divided into two groups where each larval group was randomly divided over twelve 27-1 aquaria (300 larvae per aquarium) and the stress of transfer was defined as an acute stressor. In each set of 12 aquaria, larvae were fed over 12 days three Artemia metanauplii treatments, which were tested in four aquaria per treatment, giving Artemia ArA levels of 0.59, 3.42, or 5.86 mg g(-1) dry weight (DW). One set of 12 aquaria received seawater of constant salinity (25 parts per thousand) and these larvae, exposed only to the stress of transfer, were considered as controls. The other set of 12 aquaria was supplied with seawater with a daily fluctuating salinity from 25 parts per thousand to 40 parts per thousand and back to 25 parts per thousand, exposing the larvae to 12 days of salinity change. Another trial was carried out on 30 DPH metamorphosing larvae, which were similarly stocked in the aquaria and tested with the identical Artemia treatments as the premetamorphosing larvae study.