258 
Fishery Bulletin 95(2), 1997 
tion of prey may be beneficial for both larvae and 
adults. 
The concentration of biomass at a front may be 
caused by advection (Olson and Backus, 1985) or by 
new production. Claustre et al. ( 1994) found evidence 
that suggested that the increased biomass found 
along a frontal region is due to new production. In 
the Mediterranean they found that frontal stations 
had phytoplankton biomass levels much higher than 
those at adjacent zones. These areas of high biomass 
were dominated by diatoms as opposed to flagellates 
and cyanobacteria found in typical Atlantic and Medi- 
terranean waters. They concluded that 
the high biomass levels found at the 
front are not the result of purely pas- 
sive accumulation but are the result of 
physically driven new production. 
The Loop Current and the anticy- 
clonic-cyclonic gyres found in the Gulf 
of Mexico provide an extensive (and 
dynamic) frontal habitat, and new 
production, coupled with coastal produc- 
tion advected off the shelf by ring-ring 
dipoles (Biggs and Muller-Karger, 1994), 
may play an important role in maintain- 
ing the productivity of these areas. It 
follows that stability and position of 
these mesoscale physical features may 
have a profound impact upon the spawn- 
ing success of C. pauciradiatus and on 
subsequent recruitment to the stock. 
Examination of the survey and 
transect data indicates considerable 
within- and among-year variation both 
in the position, shape, and intensity of 
the dominant physical oceanographic 
features as well as in the abundance of 
larvae and plankton along the front. 
Variation in the distribution of larvae 
along the Loop Current is evident and is 
the result of the interaction of physical and 
biological processes. As Loop water flows 
north, it makes an anticyclonic turn to the 
east and south. The meanders and eddy 
separations that result can be thought of 
as forcing mechanisms for ecology and 
population structure through divergence 
and upwelling; likewise convergence re- 
sults in passive accumulation of plankton 
and larvae and in the formation or disper- 
sion of micro patches of prey. 
Cold-core submesoscale (~50 km) cy- 
clonic rings that form along the northern 
edge of the Loop Current would also be 
expected to affect both the physical and 
biological component. In the eastern Gulf, 
these closed cyclonic domes apparently 
form as a cold perturbation on the north- 
ern boundary of the Loop Current and 
move south along the Florida shelf 
(Vukovich and Maul, 1985; Vukovich, 
© 
- 5 larvae 
© 
- 175 larvae 
Figure 1 0 
NOAA ship Oregon II cruise 173, leg 2, 12 May-26 May 1988. Symbols as 
in Figure 2. Number of larvae under 10 m 2 ranged from 5 to 58 individuals 
per station. 
-94 -93 
-92 
-91 
-90 
-89 
-88 
Figure 1 1 
NOAA ship Oregon II cruise 173, leg 2,12 May-26 May 1988. Tempera- 
ture (°C) of northern Gulf of Mexico at 200 meters. Symbols as in Fig- 
ure 2. Number of larvae under 10 m 2 ranged from 5 to 58 individuals 
per station. 
