EPIBENTHIC KRILL IMPACT PARTICLE AND FOOD WEBS: 

 DETECTION BY SUBMERSIBLE 



Marsh J. Youngbluth 



Thomas G. Bailey 



Peter J. Davoll 



Harbor Branch Oceanographic Institution, 



Fort Pierce, FL 34946 



Charles A. Jacoby 



Marine Laboratory, RD, 



Leigh, New Zealand 



Pamela I. Blades-Eckelbarger 



Harbor Branch Oceanographic Institution, 



Fort Pierce, FL 34946 



Carolyn A. Griswold 



National Marine Fisheries Service, 



Narragansett, RI 02882 



ABSTRACT 



Recently, submersible dives in the Gulf of Maine and the 

 canyons south of Georges Bank revealed that prodigious numbers of 

 fecal pellets (200-350 particles • m~ 3 ) accumulated at night in 

 5-17 m thick layers coincident with the pycnocline (15-30 m) . 

 These large, cylindrical (0.2 mm OD x 3-5 mm long) particles sank 

 rapidly (200 m • d -1 + 25 SE) and could-transport substantial 

 amounts of organic matter (35 mg C ■ m~2 * d - - 1 -) to the bottom. 

 Vertically migrating euphausiids Meqanyctiphanes norvegica 

 produced the pellets after feeding in the mixed layer. These 

 individuals represented only part of enormous (10^-10 4 

 individuals • m -3 ) aggregations of adults (25-35 mm long) which 

 remained within 10 m of the seabed day and night and appeared to 

 forage in the benthic boundary region. These discoveries are 

 significant because they improve our basic understanding about 

 the dependence of benthic communities on zooplankton grazing in 

 the mixed layer and expose variability in diel migratory and 

 feeding behaviors of a single zooplankton species, concommitantly 

 indicating the existence of unquantified pathways of particle 

 transport. Furthermore, the unexpected observations of such 

 large, epibenthic stocks of krill disclose the location of major 

 food resources that have probably supported the centuries-old 

 fishery in this region. 



205 



