_20 



3.2.1.2 Clam-worms (Nereis virens) 



Survey results for Sheep Island clam-worm populations are similar to those for soft- 

 clams (Table 3-3; Table 3-4). Abundances from rake and pit samples reflected considerable 

 annual variation with twice as many animals present at the reference area than the 

 constructed flat in 1991, the opposite result in 1992, and no animals found at either site in 

 1998 (Table 3-3). Clam- worms are large-bodied, mobile animals which periodically leave 

 their burrows to swim and breed in the water column (Pettibone, 1963). It is unclear how 

 much of the variation in rake/pit abundances was due to reproductive behaviors, natural 

 interannual variations in abundance, site-specific differences, or other factors. Data for 

 small-sized animals, i.e. the core data, indicate no difference (p>0.05) in abundance 

 between sites or between sites over time (Table 3-4). Differences among years were 

 restricted to the highest and lowest values with 1990 abundances being the least and 1998 

 being the highest (Figure 3-8). Size frequency analysis, limited to the 1991 and 1992 data, 

 indicates that while the 1991 constructed flat and reference area populations had similar 

 structures (Figure 3-9), in 1992 constructed flat populations were dominated by much 

 smaller animals than those found at the reference area (Figure 3-10). 



Table 3-3. Sheep Island Clam-worm ( Nereis virens ) Survey Results* 

 Year DM n REF n 



1990 



















1991 



16.7 



19 



33.3 



40 



1992 



27.8 



213 



4.1 



37 



1998 



















* Abundances in No. animals/m^; n = total numbers collected 



Table 3-4. ANOVA Results for Sheep Island Nereis virens Abundance (Cores) 



Effect Test 



Source 



DF 



Sum Sq. 



F Ratio 



P 



Site 



1 



0.0589 



0.1919 



0.6618 



Year 



1 



7.5649 



6.1594 



0.0001 



Site*Year 



4 



2.3019 



1.8742 



0.1164 



Error 



200 



61.4103 



0.3071 





Ecological Monitoring of a Constructed Intertidal Flat at Jonesport, Maine 



