BURROWING ACTIVITIES AND 

 SEDIMENT IMPACT OF NEPHTYS INCISA 



Wayne R. Davis 



Don C. Miller 



Environmental Research Laboratory 



U.S. Environmental Protection Agency 



Narragansett, R.I. 02882 



ABSTRACT 



It is suggested here that benthic deposit feeders are an important faunal 

 group contributing to the flux of materials, including pollutants, between the 

 benthos and overlying water. The present study has documented the burrowing 

 and feeding activities of one dominant deposit feeder, the polychaete worm. 

 Nephtys incisa, at a series of test temperatures spanning the annual thermal 

 range (0-24°C) of Narragansett Bay, R.I. New burrow development and feeding 

 are coupled events as the worm penetrates and ingests sediment. Each new 

 burrow is usually continuous with recently abandoned burrows, which results 

 in extensive perforation of the benthic sediment. Then as Nephtys ventilates its 

 burrow for respiratory purposes, sediment oxygenation along the entire 

 subsurface burrow network also occurs. Rate of new burrow building ranges 

 from one/20 days at 0°C to one/day at 24°C. 



It is hypothesized that Nephtys burrowing, feeding and irrigation activity 

 contributes significantly to substrate conditioning for development of the 

 aerobic benthic compartment. Doubtless, pollutant diagenesis is also directly 

 influenced by this creation of an oxidative environment, resulting in significant 

 pollutant fluxes to and from the benthos. 



INTRODUCTION 



The polychaete worm, Nephtys incisa, is common in silty-clay sediments of 

 the northern Atlantic estuarine and coastal waters. Its dominance in fine 

 sediment is a unique departure from other Nephtys species, all reported to be 

 active carnivores inhabiting poor to well-sorted sands (Clark, 1962; Clark efc/, 

 1962). To better understand the anomalous, silty-clay habitat preference of iV. 

 incisa, information regarding its in-sediment activities was pursued, primarily 

 through the use of laboratory microcosms. 



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