Effects of starvation stress on respiratory metabolism and biochemical composition of the sea cucumber Holothuria leucospilota

In the report, the physiological adaptation mechanisms of the tropical reef-dwelling sea cucumber Holothuria leucospilota under starvation stress were investigated, and its dynamic changes in oxygen consumption rate, ammonia excretion rate, and body wall tissue nutritional composition at 0, 7, 14, and 21 days were systematically measured. The results showed that the respiratory metabolism of H. leucospilota exhibited a typical stepwise decline pattern. The oxygen consumption rate decreased rapidly by 15.00% within 0-7 days and sharply declined by 65.00% by 21 day, and which was (7.00±1.11) μg·g⁻¹·h⁻¹. The ammonia excretion rate displayed a slow decrease during 0-7 days, a sharp decline during 8-14 days, and stabilization during 15-21 days. In terms of nutritional metabolism, short-term starvation (21 days) led to a significant reduction in the tissue moisture and lipid content (P<0.05), which decreased by 2.00% and 28.00% from initial levels, respectively, whereas organic matter, crude protein, and total carbohydrate content showed no significant differences during starvation. During starvation, the levels of 16 amino acids (including 9 essential and 7 non-essential amino acids) reached peak at 7 day, then, gradually declined, though they remained significantly higher than the initial levels after 21 days (P<0.05). These findings provide a scientific basis for optimizing feeding strategies in sea cucumber aquaculture.