108 



Abstract — Seasonal and cross-shelf 

 patterns were investigated in larval 

 fish assemblages on the continental 

 shelf off the coast of Georgia. The 

 influence of environmental factors on 

 larval distributions also was exam- 

 ined, and larval transport processes 

 on the shelf were considered. Ichthyo- 

 plankton and environmental data were 

 collected approximately every other 

 month from spring 2000 to winter 

 2002. Ten stations were repeatedly 

 sampled along a 110-km cross-shelf 

 transect, including four stations in 

 the vicinity of Gray's Reef National 

 Marine Sanctuary. Correspondence 

 analysis (CA) on untransformed com- 

 munity data identified two seasonal 

 (warm weather [spring, summer, and 

 fall] and winter) and three cross-shelf 

 larval assemblages (inner-, mid-, and 

 outer-shelf). Five environmental 

 factors (temperature, salinity, den- 

 sity, depth of the water column, and 

 stratification) were related to larval 

 cross-shelf distribution. Specifically, 

 increased water column stratification 

 was associated with the outer-shelf 

 assemblage in spring, summer, and 

 fall. The inner shelf assemblage was 

 associated with generally lower tem- 

 peratures and lower salinities in the 

 spring and summer and higher salini- 

 ties in the winter. The three cross- 

 shelf regions indicated by the three 

 assemblages coincided with the loca- 

 tion of three primary water masses 

 on the shelf. However, taxa occurring 

 together within an assemblage were 

 transported to different parts of the 

 shelf; thus, transport across the con- 

 tinental shelf off the coast of Georgia 

 cannot be explained solely by two- 

 dimensional physical factors. 



Cross-shelf and seasonal variation 



in larval fish assemblages 



on the southeast United States 



continental shelf off the coast of Georgia 



Katrin E. Marancik 



Department of Biology 



East Carolina University 



East Fifth Street 



Greenville. North Carolina 27858 



Present address: Center for Coastal Fisheries and Habitat Research 



NOAA Beaufort Laboratory 



101 Pivers Island Road 



Beaufort, North Carolina 28516 

 E mail address: Katey Marancikiffinoaa.gov 



Lisa M. Clough 



Department of Biology 



East Carolina University 



East Fifth Street 



Greenville, North Carolina 27858 



Jonathan A. Hare 



Center for Coastal Fisheries and Habitat Research 

 NOAA Beaufort Laboratory 

 101 Pivers Island Road 

 Beaufort, North Carolina 28516 



Manuscript submitted 20 December 2003 

 to the Scientific Editor's Office. 



Manuscript approved for publication 

 June 25 2004 by the Scientific Editor. 



Fish. Bull. 103:108-129(2005). 



The study of larval fish assemblages 

 provides information on community 

 structure, spawning, and larval 

 transport. Larval fish assemblages 

 are groups of larvae with similar 

 temporal and spatial distributions 

 (Cowen et al., 1993). Larval distribu- 

 tion patterns are initially determined 

 by spawning time and location; larvae 

 of species with similar spawning pat- 

 terns are initially in the same larval 

 assemblage (Rakocinski et al., 1996). 

 Physical forcing and larval behavior 

 then modify the structure of larval 

 assemblages and ultimately deter- 

 mine the outcome of larval transport 

 (Cowen et al., 1993; Smith et al., 1999; 

 Hare et al., 2001). 



Marine protected areas (MPAs) are 

 portions of the marine environment 

 designated to "provide lasting protec- 

 tion for part or all of the natural and 

 cultural resources therein" (Federal 

 Register, 2000). A number of specific 

 conservation objectives are encom- 



passed by this definition, such as 

 protecting small areas with histori- 

 cal significance or aesthetic quality, 

 or protecting much larger areas to 

 enhance fisheries through increases 

 in spawning stock biomass and the 

 supply of recruits to surrounding ar- 

 eas (Crowder et al., 2000). However, 

 whether an MPA provides recruits 

 to other areas is difficult to quantify 

 and involves determining the fate 

 of larvae and juveniles spawned in 

 a protected area (Stephenson, 1999; 

 Warner et al., 2000). 



MPAs are under consideration as 

 a fisheries management tool on the 

 southeast United States continental 

 shelf (Plan Development Team, 1990), 

 and larval assemblage studies would 

 provide useful information regard- 

 ing spawning and larval transport. 

 Although substantial larval fish re- 

 search has been conducted on the 

 southeast U.S. continental shelf, no 

 studies have examined the dynamics 



