FISHERY BULLETIN: VOL. 76, NO. 1 



ambiseta, and Heteromastus filiformis were the 

 dominant organisms in the silt-fine sands around 

 and beneath the serpulid tubes. Other 

 polychaetes, such as Cistena gouldii and Streblo- 

 spio benedicti, inhabited the surrounding sedi- 

 ment. 



Two seasonal changes were noted in the 

 polychaete distributions of the Hydroides dian- 

 thus assemblage. Adult Polydora ligni were not 

 found in the August grab samples; however, when 

 dredge hauls were sieved through a 250-mm mesh 

 screen, juveniles down to the eight or nine setiger 

 stages were collected. Harmothoe extenuate was 

 totally absent from the fall collections, but reap- 

 peared the following spring. 



Oyster Assemblage (D) 



The oyster assembl age ( Figure 1 ) was the first of 

 the epifaunal-infaunal communities to be sam- 

 pled. Since this study was described in detail in 

 Maurer and Watling ( 1973), it will only be briefly 

 described here for purposes of comparison with the 

 other epifaunal-infaunal groups. Twenty species 

 of polychaetes were collected on oyster bars in 

 Delaware Bay and in the Broadkill, Mispillion, 

 Murderkill, St. Jones, and Leipsic Rivers. Four of 

 the species, Hydroides dianthus, Polydora 

 websteri, P. ligni, and S. vulgaris, were associated 

 directly with the shell substratum. Polydora 

 websteri is known to burrow into oyster shells and 

 dissolve the shell to form U-shaped cavities lined 

 with detritus (Zottoli and Carriker 1974). Poly- 

 dora ligni forms silty mucous tubes which may be 

 present in very high densities on the external sur- 

 face of the oysters. 



Five species of polychaetes, Harmothoe ex- 

 tenuata, L. sublevis, Eteone heteropoda, E. lactea, 

 and Eumida sanguinea, were found to inhabit the 

 mud and debris associated with the epifaunal or- 

 ganisms. Other species such as Scoloplos fragilis, 

 Spiochaetopterus oculatus, Cistena gouldii, and 

 Streblospio benedicti, were found on nearby soft 

 bottoms. Nereis succinea was collected in all types 

 of sediment. 



Small Bays (F) 



From 1968 to 1970, 273 samples were taken in 

 Rehoboth and Indian River Bays (Figure 1) during 

 summer and winter, with emphasis on the former. 

 Seventeen polychaete species were collected in In- 

 dian River Bay in summer 1968, 14 in winter 



218 



1969, 15 in summer 1969, and 17 in winter 1970. 

 During the same time periods, 28, 13, 20, and 14 

 polychaete species, respectively, were collected in 

 Rehoboth Bay. Based on density and frequency of 

 occurrence, the following five species of 

 polychaetes emerged as dominants: Capitella 

 capitata, Glycera americana, Lumbrineris tenuis, 

 Scoloplos fragilis, and Glycinde solitaria. 

 Capitella capitata was found in both bays in high 

 numbers in the summer samples only. Only three 

 of the dominant organisms, L. tenuis, S. fragilis, 

 and Glycera americana, were present during all 

 sampling periods. Nereis succinea was another 

 important species. Logan and Maurer (1975) 

 found that A^^. succinea and Heteromastus filifor- 

 mis dominated monthly samples throughout the 

 year in the upper Indian River Bay; N . succinea 

 was postulated to be an indicator organism for 

 thermal pollution. 



Watling (1975) reported that Streblospio bene- 

 dicti and C. capitata were the dominant benthic 

 species in a deposit-feeding community in a small 

 cove of Rehoboth Bay. Other species, such as 

 Polydora ligni and H. filiformis, were also impor- 

 tant. His study further indicated that S. benedicti 

 and C. capitata showed opportunism and rapidly 

 recolonized the area after a summer die-off, pre- 

 sumably taking advantage of available food re- 

 sources. Brania clavata, Exogone dispar, and H. 

 filiformis gradually increased in numbers as the 

 community stabilized. 



Coastal Fauna (G, H, I) 



The Hen and Chickens Shoal (area H), im- 

 mediately adjacent to the bay mouth, showed the 

 greatest resemblance to the estuarine fauna. 

 Bethany Beach (area G) and the northeast sta- 

 tions off the mouth of Delaware Bay (area I) ap- 

 peared more like the offshore assemblages (Figure 

 1). The southeastern portion of area I was also 

 estuarine in character (Watling et al. 1974). 

 Tharyx acutus and Harmothoe extenuata were the 

 dominant polychaetes in area H. Tharyx acutus 

 occasionally occurred in the bay and frequently 

 offshore, but never in the densities recorded in 

 area H. Tharyx acutus was particularly important 

 during January through April, when it reached 

 densities of 960/m2. Harmothoe extenuata was pres- 

 ent in large numbers in Delaware Bay, but very 

 rarely offshore. Pettibone (1963a) stated that H. 

 extenuata is a highly adaptable species which oc- 

 curs intertidally and at great depth on all types of 



