CAROTENOIDS IN THE TIGER PRAWN PENAEUS-ESCULENTUS DURING OVARIAN MATURATION

Female Penaeus esculentus Haswell were collected by 15 to 20 min durat ion trawls during 1990. Carotenoids were analysed in the digestive gla nd, abdominal muscle, the remainder of the body (hereafter called ''in tegument'') and ovary of prawns in Stage 2 through Stage 4 (fully matu re) of maturation. The only oxycarotenoids (xanthophylls) identified w ere astaxanthins or astaxanthin esters; occasionally low levels of bet a-carotene were detected in the digestive gland. The concentrations of astaxanthin monoesters (AM) and diesters (AD) were highest, with only minor amounts of free astaxanthins (Ast), except in the maturing ovar ies, where free astaxanthins predominated (up to 80% of the total caro tenoid). Of the total carotenoid, 82 to 94% was in the integument, but at maturity the digestive gland contained 10.7 +/- 3.4% and the ovary 5.6 +/- 0.9% of the total carotenoid. Only the ovary increased in mas s during maturation, reaching up to 5.2% of total prawn mass. During t his period, digestive gland concentrations of AM, AD and Ast all incre ased (total 20 to 120 mu g g(-1)), levels in the muscle and integument varied little throughout maturation (total similar to 0.4 and 100 mu g(-1), respectively); ovary AM levels remained low throughout (1.5 to 1.2 mu g g(-1)), AD increased from only 2 to 5 mu g g(-1), but Ast inc reased from 2 to 34 mu g g(-1). Apart from the ovary, AM concentration s were the most variable. In common with other decapod Crustacea, the maturing ovary of P. esculentus contained high levels of carotenoids, indicating that these may have an important role in early development. The natural diet of P. esculentus includes a variety of carotenoids, but except for a little beta-carotene, the digestive gland, where abso rption occurs, contained astaxanthins, with only an occasional trace o f beta-carotene. This suggests that the conversion of dietary caroteno ids to astaxanthin occurs soon after ingestion.