DISCUSSION 



The panels at 100, 500, and 1000 m represent a series of samples collected along a straight line at 

 increasing distances from the quarry. The direction of this transect was the same as the ebb tide flow of 

 the effluent plume. The data described a consistent decrease in panel recruitment of Teredo navalis from 

 601 at 100 m to 388 at 1000 m. This trend may indicate that recruitment of 7'. navalis is enhanced m 

 the effluent mixing zone, even though the differences in shipworm densities were not statistically different 

 (p < 0.05) from 100 to 1000 m. 



This was the first study investigating the distribution of Teredo bartschi beyond the undiluted effluent 

 or F-F site. Panels at the 100 m sampling site were within the effluent mixing zone, and were periodically 

 flushed by effluent waters; the depth at this site was 5 m. Incursion of effluent water permitted the 

 successful recruitment of T. bartschi in panels at 100 m. Studies on the life history of this species from 

 1983-1985 established that T. bartschi could grow and reproduce at ambient water temperatures in the 

 Millstone area (report in preparation), but may require higher effluent temperatures for successful recruit- 

 ment. The panels at 500 and 1000 m sampling sites were at depths of approximately 10 m and were not 

 exposed to effluent water, under 2-unit operating conditions. No T. bartschi were found at 500 or 1000 m. 



A similar link between high temperatures and the distribution of this species has been indicated by 

 others; Teredo bartschi has been recorded outside its normal range only in the vicinities of thermal effluents. 

 Hoagland and Turner (1980) reported that T. bartschi was present in panels at the mouth of the Waretown 

 Creek and in Forked River from 1975 to 1978; both areas were in the mixing zone of the thermal plume 

 from the Oyster Creek Nuclear Generating Station, Bamegat Bay, New Jersey. 



In summary, a reproductive population of Teredo bartschi was collected at a site 100 m outside of 

 the quarry cuts, within the mixing zone of 2-unit effluent. Preliminary data indicate that water temperatures 

 above ambient are needed for larval recruitment, i.e., some incursion of effluent water; however, additional 

 studies are needed to determine the exact conditions needed for T. bartschi settlement, and to determine 

 whether the local distribution of T. bartschi will expand under 3-unit operating conditions. Additional 

 studies may also substantiate the observed trend of increasing T. navalis abundance with decreasing distance 

 from the quarry cuts. 



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