Life history of a dominant polychaete, Polygordius jouinae, in inner continental shelf sands of the Mid-Atlantic Bight, USA

Abstract

The life history of the polychaete Polygordius jouinae Ramey, Fiege, and Leander 2006 was studied in the sandy sediments of the LEO-15 research area off the coast of Tuckerton, New Jersey (39°27.69′N, 74°15.81′W). Divers collected sediment cores biweekly, from February 2004 to November 2005 to examine the temporal patterns of abundance and size–frequency distributions of P. jouinae. These parameters were also examined (for the first time) for P. jouinae in samples taken in ambient sediments and in three reciprocal 3 to 5-day sediment transplant experiments that were part of a previous, unrelated study at coarse sand and muddy sand sites (∼3 km apart) at LEO-15 in the summers of 1994 and 1995. Analysis of these previous data along with the current data provided a larger set of values for P. jouinae, as well as further insight into the life history, habitat selection, and dispersal of P. jouinae (not considered in previous studies). Polygordius jouinae is gonochoristic and the population was mostly composed of sexually mature individuals in late May 2004 and 2005. The reproductive period usually occurs from May to August and individuals that spawn generally have a 1-year life span. Non-spawning individuals of P. jouinae could potentially live longer than 1 year and therefore the population may sometimes consist of individuals of two generations. Recruitment begins no later than July as recently settled individuals (≤9 mm body length), which were not present during the first week of June 1995, 2004, and 2005, first appeared in July in all 3 years. The smallest individual was 2.01 mm long and 0.07 mm wide and this provides the first estimate of size at initial recruitment. Although some worms in sediment trays likely settled as larvae, most worms were recently settled juveniles (length categories 6 and 9 mm) transported in from the surrounding sediments, presumably as a consequence of re-suspension or bed load transport. As expected, larger individuals were present later in September. Although it is unknown whether P. jouinae were transported actively or passively these data suggest that recently settled juveniles are capable of habitat selection (prefer sand over mud) and show that post-settlement transport and selection influence community structure.