Tabic .'!. — Continued. 



Leptocheirus pinguis 

 Microdeutopus gnllotalpa 

 Microdeutupus anumalus 

 Pseudunciola vbliquua 



COROI'HIIDAE 

 Cerapus tubularis 

 Corophium acherusicum 

 Corophium tuberculatum 

 Corophium crassicorne 

 Corophium bonelti 

 Erichthonius brasiliensis 

 Unciota inermis 

 Unciola irrorata 

 Vnciola serrata 

 Unciola dissimilis 



GAMMARIUAE 

 Elasmopus leu is 

 (iammarus mucronatus 



HAUSTORllDAE 

 Acanthohaustorius mittsi 

 Bathyporeia parkeri 

 Parahaustorius attenuatus 

 Parahaustonus holmesi 

 i^otohauatorius deichmannae 

 Protohaustoriuti wigleyi 

 Acanthohaustorius n. sp. #1 

 Acanthohaustorius n. sp. tt2 



ISAEIDAE 

 Photis dentata 



ISCHYROCERIDAE 

 Jassa falcata 



LILJEBORGIIDAE 

 Listriella barnardi 

 Sextonia americana 



LYSIANASSIDAE 

 Lysianasna alba 

 Psammonyx nobilis 

 Orchomenella pinguis 



OEDICEROTIDAE 



Svnchelidium americanum 



PHOXOCEPHALIDAE 



Paraphoxus spinosus 

 Phoxocephalus holbolU 

 Trichophoxus epistomus 



PLEUSTIDAE 

 Stenopleustes gracilis 

 StenopU'ustes inermis 

 Pleusym tes gla ber 



CAl'RELLIDAE 

 Aeginina longicornis 

 Caprella unica 

 Caprella penantis 

 Paracaprella tenuis 

 Luconacia incerta 

 DECAPODA 



HIPPOLYTIDAE 

 Eualus pusiolus 



CRANGONIDAE 



Crangon septemspinosa 



THALASSINIDEA 

 CalUanassa atlantica 

 Axiustfl 



PAGURIDAE 



Pagurus longicarpus 

 Pagurus pollicaris 



PORTUNIDAE 

 Ovalipes ocellatus 



CANCRIDAE 

 Cancer borealis 

 Cancer irroratus 



XANTHIDAE 

 Neopanope texana sayi 

 Xanthid 141 



PINNOTHERIDAE 

 Dissodactylus mellitae 

 Pinnotheres maculatus 

 Pmnixa ffl 



MAJIDAE 

 Libinia dubia 

 Libinia emarginata 



The cluster analysis of 1972 faunal data revealed one 

 large group of 43 stations (Fig. 40) with relatively homo- 

 geneous fauna (similarity >50%). This group occurred 

 mostly in muddy, deepwater sediments throughout cen- 

 tral and western LIS; 37 of the stations had >69% 

 silt/clay, and 38 were > 15 m deep. Table 4 lists the fauna 

 typical of these fine sediments in 1972, giving mean 

 densities per square meter as well as coefficient of varia- 

 tion (standard deviation -^ mean density X 100) and fre- 

 quency of station occurrences for each of the 17 species 

 found at a majority of the 43 stations (an 18th species, 

 the anthozoan Ceriantheopsis americana, was present in 

 a majority of samples analyzed for April and September 

 1973 though not for 1972). The 1972 mud-bottom assem- 

 blage was dominated by small bivalves, including Nu- 

 cula proximo and Yoldia limatula (burrowing deposit 

 feeders), Pitar morrhuana, and especially Mulinia later- 

 alis (suspension feeders). Other very frequently occurring 

 constituent species were the polychaete Nephtys incisa 

 (burrowing deposit feeder), and gastropods Nassarius 

 trivittatus (surface deposit feeder) and Acteocina canali- 

 culata (carnivore). Overall faunal density was extremely 

 high (x = 10,400/m-). Diversity was quite low, due to low 

 species richness and dominance by Mulinia. As indi- 



cated by frequencies of occurrence and coefficients of 

 variation, Nephtys, Nassarius, Acteocina, Mulinia, and 

 Pitar had relatively even abundances in the mud-bottom 

 areas; distributions of the remaining species were 

 patchier. 



Table 4 also lists mean densities, coefficients of varia- 

 tion, and frequencies of occurrence of these 18 species 

 based on the more limited data available for April 1973 

 (one sample from each of 13 stations) and September 

 1973 (16 samples, 13 stations; these stations were fairly 

 evenly distributed over the area in which the mud assem- 

 blage was present in 1972, as was also the case for 1973 

 sampling in the sand and transitional assemblages dis- 

 cussed below). 



Numbers of individuals and species declined precipi- 

 tously from summer 1972 to April 1973, and no recovery 

 was apparent by September 1973. The decline affected 

 almost all taxa; only the anthozoan Ceriantheopsis, poly- 

 chaetes Nephtys and Pherusa, and bivalve Nucula 

 showed September 1973 densities greater than or equal to 

 two-thirds as high as their summer 1972 values. Species 

 diversity and equitability increased, reflecting the re- 

 ductions in populations of dominants such as Mulinia 

 and Pitar. This "population crash" had been reported for 

 portions of central LIS (McCall 1977), but its areal ex- 

 tent had not been delimited. Our evidence indicates that 

 the decline extended over the entire area containing the 

 mud assemblage (Fig. 40) with the following exceptions: 

 the westernmost station (5) had slightly increased 

 numbers of individuals and species in 1973, though 

 Mulinia and Pitar were replaced as dominant species by 

 several polychaetes and Ceriantheopsis; station 72, in 

 relatively shallow water near New Haven, also had a shift 

 in species composition toward polychaetes with little 

 change in overall faunal density or species richness; 

 while station 86, the easternmost mud bottom area for 

 which we have 1973 data, contained a typical Mulinia as- 

 semblage in April 1973, but Mulinia had disappeared 

 and overall numbers of species and individuals were 

 greatly reduced by September 1973. 



A somewhat less widespread, more variable faunal as- 

 semblage, found at 12 stations with faunal similarity 

 >37%, occurred primarily along the Long Island coast, in 

 sandy sediments at shallow depths (Fig. 40). All stations 

 in this group contained <3.7' e silt/clay, and all were in 

 water <6.1 m deep. This group of stations thus repre- 

 sents the other extreme of soft-bottom habitat types 

 among our LIS samples. Only 15 species were present at 

 >50'^c of the 12 stations in 1972 (Table 5) though overall 

 species richness (and diversity) were considerably 

 greater than in mud bottoms. The assemblage was domi- 

 nated by three suspension-feeding bivalves, Tellina 

 agilis, Ensis directus, and Spisula solidissima. Other 

 prominent members were Nephtys picta and Nassarius 

 trivittatus as well as a suspension-feeding gastropod, 

 Crepidula fornicata, and the omnivorous hermit crab, 

 Pagurus longicarpus. 



Based on the few samples processed from September 

 1973 (Table 5), this habitat did not experience a faunal 

 decline comparable with that described above for the 



