Megafaunal communities along a depth gradient on the tropical Brazilian continental margin

Abstract

The species composition, abundance and diversity patterns of the epibenthic megafauna and fish community from the tropical Brazilian continental margin were analysed based on 42 bottom trawls from the Campos Basin continental shelf and slope. Trawls were collected aboard R/V Gyre during autumn 2008 from depths of 13 to 2030 m. Overall, 452 species belonging to five main taxa were identified: teleosts (Actinopterygii) were represented by 196 species, crustaceans by 113 species and echinoderms by 108 species. These three groups contributed 92% to the 452 taxa. Several species (289) were recorded only once or twice, and the species accumulation curves showed no signs of being close to reaching asymptotic values. A tendency of increasing diversity and richness with depth was observed. Analysis of the trawls showed the existence of megafaunal assemblages significantly associated with depth and water mass. The shelf group (13-100 m) had subgroups associated with Coastal Water (CW) and South Atlantic Central Water (SACW). The upper-slope group (376-501 m) was found exclusively under the influence of SACW. The mid-and lower-slope group (978-2030 m) had two subgroups associated with the presence of Antarctic Intermediate Water and North Atlantic Deep Water. The 39 typifying species contributed 90% to the global similarity. Teleosts and squids greatly contributed to the within-group similarity over the shelf, while decapods, echinoids and galatheids contributed to the upper-slope assemblage. Deep-sea isopods and decapods mostly contributed to the mid-and lower-slope assemblages.

Explainable Classification Methods for Fish Species Detection Using Hydroacoustic Data

“…The attributes SL and LD were revealed as very important for the composition of the rules. Those descriptors are directly related to other abiotic (eg, temperature and water salinity) and biotic (food availability) factors that influence the places where these marine beings inhabit [26], [27]. According to [27], depth is the main structuring factor of marine megafauna communities (macroscopic animals).…”

The trophic ecology of marine catfishes in south-eastern Brazil

“…Situation 1 can be sustained, as lolignid squids ( Doryteuthis plei and D. sanpaulensis ) have a strong association with the sea bottom and are considered abundant in the inner shelf from 10 to 50 m (Robin et al ., 2014; Costa et al ., 2015). A short distance south (100 km), in the Cabo Frio upwelling region, Soares et al .…”

“…Situation 1 can be sustained, as lolignid squids (Doryteuthis plei and D. sanpaulensis) have a strong association with the sea bottom and are considered abundant in the inner shelf from 10 to 50 m (Robin et al, 2014;Costa et al, 2015). A short distance south (100 km), in the Cabo Frio upwelling region, Soares et al (2014) found similar δ 15 N values (higher than for other invertebrates of the present study) of loliginid species (D. plei -12.5‰ and D. sanpaulensis -11.0‰) compared with our results (13.3‰).…”

Feeding habits and trophic status of Merluccius hubbsi along the northernmost limit of its distribution in the South-western Atlantic

“…Prey selection is often proportional to prey availability in the environment (Link & Garrison, 2002), and preference for D . volitans could be attributed to its abundance in the study area, since it occurs at great densities along the shelf between 20–23°S (Costa et al ., 2015). Moreover, the protein content of D .…”

“…In Brazilian waters, Argentine hake is considered a keystone species in the demersal community of the outer shelf and upper slope between 22–27°S (Nascimento et al ., 2012), as well as between 20–23°S (Costa et al ., 2015). Despite the importance of M. hubbsi in the demersal ecosystem, its trophic relationships have been poorly understood.…”