Reproductive biology of porcellanasterid asteroids from three abyssal sites in the northeast Atlantic with contrasting food input

Abstract

The reproductive biology of the abyssal asteroids Hyphalaster inermis, Styracaster chuni, and S. horridus from the Porcupine Abyssal Plain (PAP), the Madeira Abyssal Plain (MAP), and the northwest African slope (NWA) is described and compared. The most northern location (PAP) is subjected to a strong seasonal input of aggregated phytodetritus to the seabed. The site at MAP does not receive a significant signal of phytodetritus but has been affected recently (ca. 1,000 years ago) by a relatively organic-rich turbidite. The site in the NWA is affected by a strong upwelling regime, which provides the seabed with important inputs of surface-derived organic matter. The gametogenic processes were similar in all three species at the three locations. Oogenesis was asynchronous. The previtellogenic oocytes grow to a size of ~150–200 µm before undergoing vitellogenesis. Most of the volume of the ovary was occupied by large vitellogenic oocytes of 300–500 µm in diameter. The maximum oocyte size was ~650 µm. The males had a continuous supply of spermatozoa densely packed in the lumen of the testes. There were no seasonal variations in gonad index (GI), pyloric caecum index (PCI), and fecundity for any of the species. The GI of H. inermis was similar between locations, indicating a constant allocation of energy to reproduction. The mean GI of S. horridus differed between locations, but there was no clear pattern. Size at maturity and average adult size were larger in the specimens from PAP and NWA than in the specimens from MAP. Fecundity was significantly higher in the specimens from PAP and NWA than in the specimens from MAP. The results are discussed in relation to phylogenetic constraints on gametogenesis and the effects of food quantity and quality on reproductive output.