WENNER: SPONGE-CORAL HABITAT FISHES 



Table 4. — Ten most numerically abundant demersal teleosts taken 

 spring 1978 in 57 sponge-coral habitat trawl tows, South Atlantic 

 Bight. 



TABLE 5. — Ten most important demersal teleosts by weight in 57 

 sponge-coral habitat trawl tows taken spring 1978, South Atlantic 

 Bight. 



Species 



Weight 

 (kg) 



% of 

 catch 



Cumulative No. of 



% occurrences 



Stenotomus 



aculeatus 

 Haemulon 



aurolmeatum 

 Holacanthus 



isabelita 

 Calamus 



leucosteus 

 Stephanolepis 



hispidus 

 Centropristis 



striata 

 Chromis 



enchrysurus 

 Rhomboplites 



aurorubens 

 Calamus 



nodosus 

 Balistes 



capnscus 



The five species of group D were rare in the trawl 

 collections but had their greatest frequency of oc- 

 currence in night trawl tows from reef sites in depths 

 >30 m. Members of group E were more abundant 

 than group D and were collected primarily in night 

 samples. They were not, however, restricted to reef 

 sites, since five species (Synodus foetens, Aluterus 

 heudeloti, Scorpaena brasiliensis, Syacium papil- 

 losum, and Ophidion beam) cooccurred in site group 2 

 (night open-shelf collections). Generally, this group 

 was rarely found in day trawl tows but was widely dis- 

 tributed and abundant in night samples from all 

 sites. 



Species group F occurred almost exclusively at 

 night and was most frequently encountered and 



abundant at site group 10 (6 night tows at reef 3; 1 

 night tow at reef 4). Low constancy values were ob- 

 served for species at site groups 2, 7, 8, 9, and 12, 

 whereas they exhibited high constancy and fidelity 

 values for site group 10. 



Group G had seven species that were relatively rare 

 but most frequently found in daytime tows with max- 

 imum abundances in site group 7 (11 day samples 

 from 4 reef areas). Group H also contained fishes that 

 were widely distributed among site groups but not 

 very abundant. Highest constancy and fidelity values 

 were in site group 3 where species in group H had 

 maximum abundance and frequency of occurrence. 



Although members of species group I were found in 

 several site groups, this assemblage was considered 

 to be a regular component of the deeper reef sites 

 where their greatest frequencies of occurrence and 

 abundance were observed in day tows. Their affinity 

 for deeper reefs is supported by high constancy and 

 fidelity values in site groups 4 (3 day tows at reef 2, 

 depth = 44 m), and moderate constancy and fidelity 

 values in site groups 3 (4 day and 1 night tow at reef 5, 

 depth = 42 m) and 5 (5 day tows at reef 1, depth 

 = 37 m). 



Diversity 



More species were collected in night trawl tows in 

 both open-shelf and reef habitats than in day tows. 

 Comparisons of the mean number of species per tow 

 in day and night samples at the open-shelf site 

 showed night tows (x = 7.3) had significantly more 

 species than day tows (x = 3.6) at the 95% probability 

 level (t = 2.905, df = 9). The same trend was ob- 

 served for samples from the sponge- coral habitat, 

 pooled by time of collection. The 28 day tows had 

 significantly fewer species (x = 10.8) than night tows 

 {x = 19.6) at the 99% level (t = 7.777, df = 55). 



Comparisons of the number of species per tow for 

 each time period in the two habitat types showed that 

 mean values for the open-shelf habitat were one- 

 third to one-half the mean values for various reef 

 sites. Night tows in the reef habitat had higher 

 species diversity values than day tows. This was at- 

 tributed to increased evenness and species richness 

 (Table 6). 



DISCUSSION 



Standard otter trawl collections in the sponge- coral 

 habitat (inshore and intermediate reefs of Miller and 

 Richards 1979) yielded demersal teleost biomass es- 

 timates that were an order of magnitude higher than 

 those of the open shelf (Table 7). Although these 



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