FISHERY BULLETIN: VOL. 76, NO. 1 



ANIMAL-SEDIMENT RELATIONSHIPS 



To describe some of the sediment associations of 

 the dominant species of Delaware Bay, correla- 

 tions were made with median grain size and per- 

 centage of silt-clay using Spearman's p (a = 0.05). 

 Nephtys picta was collected in sediments with an 

 unweighted mean grain size of 2.1c/) and in 1-10% 

 silt-clay (x = 4.7%). Increasing abundance of A^. 

 picta was associated with increasing amounts of 

 silt-clay within the range in which it occurred. 

 Glycera dibranchiata was found in sediment with 

 up to 50% silt-clay (3c = 13.3%), and a mean size 

 ranging from 0.8 to 6.6(^ (x = 2.7). There was a 

 positive association between numbers of individu- 

 als and increasing silt-clay content. No other as- 

 sociations were significant. 



Two of the dominant species were found primar- 

 ily in muddier sands. Heteromastus filiformis has 

 been described as a member of soft sediment com- 

 munities in Delaware Bay (Kinner et al. 1974) as 

 well as elsewhere (Dean and Haskin 1964). The 

 species inhabited a wide range of sediments, M 

 0.08-6.5(^ (x = 3.7), and was positively correlated 

 with increasing silt-clay and increasing median 

 and mean grain size. Streblospio benedicti occur- 

 red in sediments with a wide range of silt-clay 

 (2.5-59.0%). The distribution of the species was 

 not correlated with median grain size, silt-clay, or 

 mean grain size. Streblospio showed an even 

 greater affinity for the areas along the Delaware 

 and New Jersey shoreline than did H. filiformis. 



Correlations were also made between measures 

 of sediment and five of the dominant polychaetes 

 of the offshore assemblages. Lumbrinerides acuta 

 (0.76-2.40(/)) and Goniadella gracilis (0.76-2.49(/)) 

 were negatively associated (a = 0.05) with in- 

 creases in median </> and positively correlated with 

 an increase in the percentage of sediment >1 mm 

 in diameter. Both species showed correlations of 

 high density with more poorly sorted sediments. 

 Nichols (1970) has postulated that although sort- 

 ing is not well understood biologically, positive 

 correlations with well sorted sediments may indi- 

 cate niche specificity, while poor sorting suits a 

 wider variety of needs. The larger sediment sizes 

 probably facilitate burrowing. 



Aricidea catherinae (0.34-2.64(/)) was negatively 

 associated with an increase in the size of the me- 

 dian (I). This deposit-feeding species builds a flexi- 

 ble mucous tube and is far less mobile than L. 

 acuta and G. gracilis. Sediments containing parti- 

 cles >1 mm may be difficult for this fragile species. 



220 



Aglaophamus circinata was not significantly as- 

 sociated with any sediment parameters. However, 

 it was found in a range of sediment (0.34-2.64(^) 

 similar to that of the other species. Sediments 

 which contained the greatest densities of 

 Spiophanes bombyx were generally well sorted 

 (o- = 0.21-0.570) with between 25% and 50% of 

 the sediment >04>. There was a negative associa- 

 tion (a = 0.05) between S. bombyx and sediment 

 >1 mm. This species was also negatively as- 

 sociated with an increase in the standard devia- 

 tion of (/) indicating its preference for a well-sorted 

 sediment. 



GENUS-SPECIES RELATIONSHIPS 



A comparison was made of the genus to species 

 ratios for each of the estuarine coastal and offshore 

 areas to obtain information on diversity and 

 speciation. The midshelf station had the highest 

 ratio of 1.0:1.6 with the Serpulidae and Mytilus 

 assemblages second (1.0:1.4). Coastal areas were 

 next with Hen and Chickens Shoal and Bethany 

 Beach 1.3 and off the bay mouth 1.2. The areas 

 within Delaware Bay and the small bays were as 

 follows: baywide (1.3), intertidal (1.3), bay mouth 

 (1.0), oyster beds (1.2), and small bays (1.1). The 

 epifaunal-infaunal speciation ratio does not 

 reflect the stability of the habitat, but rather the 

 greater number of niches due to a mixed sub- 

 stratum. Winter reductions in species diversity in 

 the Mytilus assemblage due to storms and mussel 

 mortality emphasize the fragile nature of the en- 

 vironmental stability. 



TAXONOMIC NOTES 



Revisions and synonymies that appear in 

 polychaete taxonomic literature are often not in- 

 cluded in ecological publications for a long time. 

 Based on suggestions from Marian Pettibone, we 

 have included a section describing some of the 

 systematic changes that affect the east coast of the 

 United States. We formally acknowledge her for 

 providing us with much of the information in- 

 cluded in this section. 



Ampharetidae 

 Hypaniola florida (Hartman) 



In a recent paper Pettibone (1977) has pre- 

 sented the synonomy and distribution of the es- 

 tuarine species, Hypaniola florida (Hartman). The 



