Population differences in gonad and pyloric caeca cycles of the New Zealand seastarSclerasterias mollis (Echinodermata: Asteroidea)

Abstract

Date of final manuscript acceptance: September 24, 1990. Communicated by J.M. Lawrence, TampaAbstract. Inshore and offshore populations of Sclerasterias moll& (Hutton, 1872) were sampled on the outer continental shelf off the Otago Peninsula, New Zealand, and their nutritional and reproductive cycles are described from [1985][1986]. Histological changes in the gonads are generally typical of other asteroids. The gametogenic cycle takes 12 too. The gonad and pyloric caeca indices in both females and males had an inverse relationship. S. mollis accumulates nutrients in the pyloric caeca during summer and early autumn. The gonads develop in the autumn and winter. Offshore seastars were much larger and had significantly higher gonad and pyloric caeca indices than inshore individuals. These differences in body sizes and organ indices arise from differences in food availability and/or population density.

Seasonal changes in biochemical composition of body walls, gonads and pyloric caeca in two populations ofSclerasterias mollis (Echinodermata: Asteroidea) during the annual reproductive cycle

“…8 b). Seasonal changes in the carbohydrate contents of the pyloric caeca of the two populations showed similar trends, which closely followed changes in the pyloric caeca index (see Barker and Xu 1991). The offshore population had consistently higher carbohydrate contents, with significant differences between the two populations in May, June, August, November (ANOVA, P<0.001) and December (ANOVA, P<0.05) 1985, and May, July and September, 1986 (ANOVA, P<0.001).…”

“…Protein in the ovaries of Sclerasterias mollis was about twice that of carbohydrate and lipid during oogenesis, and over twice that of carbohydrate and lipid levels during Stage I (see Barker and Xu 1991 for definitions of reproductive stages), while protein levels of testes were more than twice the combined level of carbohydrate and lipid levels during spermatogenesis, and over three times that of carbohydrate and lipid levels during Stage 1. This indicates that protein is also a major constituent in the gonads of S. mollis', however its level is rather constant, with a slight increase during gonadal development.…”

“…However, marked differences in gonad and pyloric caeca indices occur in offshore and inshore populations (Barker and Xu 1991). In order to determine whether these marked differences in organ indices were also reflected in differences in biochemical composition of tissues, the seasonal changes in carbohydrates lipids and proteins were determined for inshore and offshore populations of both female and male S. mollis.…”

Annual changes in the steroid levels in the testis and the pyloric caeca ofSclerasterias mollis(Hutton) (Echinodermata: Asteroidea) during the reproductive cycle

“…rubens. However, biochemical studies of the gonads and the pyloric caeca of S. mollis have shown that there were differences between sexes in biochemical components in the gonads but not inthepyloric caeca of this species Barker 1990d, Barker andXu 1991b). Generally, there is a resting stage in reproductive cycle of echinoderms following spawning (Boolootian 1966).…”

Reproductive output and consistency of source populations in the sea star Pisaster ochraceus

“…Observers of other asteroid species have noted that individuals with large gonads are sometimes associated with areas of high resource quality (Crump 1971, Barker & Xu 1991. For example, in New Zealand, the sea star Sclerasterias mollis had larger pyloric caecum and gonad indices at a site where scallops were the primary prey available than at a site where the diet consisted of gastropods and other small prey (Barker & Xu 1991). When Pisaster occur at sites with abundant mussels and barnacles, the blue mussel Mytilus trossulus is the dominant prey in the diet, whereas acorn barnacles are rarely consumed (Sanford 1999, see also Feder 1970.…”