that an additional 19% of the total corrected sum of squares was due to the difference between the two 

 sampling dates (April 28 and May 9). Based on the harmonic regressions, the effect of tidal stage on 

 sample density at station C was inverse for Stage 1 compared to Stage 3 and 4 larvae (Fig. 12). Stage 1 

 density increased during ebb tides and declined during flood tides. This pattern was attributed to the 

 flushing of Stage 1 larvae from the upper portion of the Niantic River, where they were more abundant, 

 into the lower portion during ebb tide (NUSCo 1985). The decline during flood tide was caused by water 

 from Niantic Bay that contained few Stage 1 larvae entering the river. The inverse relationship for Stage 

 3 and 4 larvae was attributed to vertical migration in response to tidal flow as a retention mechanism 

 (NUSCo 1984), where the larvae remained on or near the bottom during an ebb tide and moved up in 

 the water column during flood tides. This tidal behavior of Stage 3 and 4 larvae would help explain the 

 lack of diel behavior at station C, as shown above (Fig. 10). 



6- 



A\ 



STAGE 3 AND 4 



2 4 



, FLOOD 



8 10 12 14 16 1i 

 EBB I FLOOD , 



20 22 24 26 

 EBB I 



HOUR 



Figure 1 2. Harmonic regression models of larval winter flounder abundance (log density per 500 m ) during 24-h 

 tidal cycles at station C for developmental Stage 1 and Stage 3 and 4 combined. 



67 



