Biodiversity of macrofaunal assemblages from three Portuguese submarine canyons (NE Atlantic)

Abstract

a b s t r a c tThe macrofaunal assemblages from three Portuguese submarine canyons, Nazaré , Cascais and Setú bal were studied from samples collected at their upper (900-1000 m), middle (3200-3500 m) and lower sections (4200-4500 m) and at the adjacent open slopes ( $ 1000 m), during the HERMES cruises D297 (R.R.S. Discovery, 2005) CD179 (R.R.S. Charles Darwin, 2006) and 64PE252 (R.V. Pelagia, 2006). The taxonomic composition and patterns in biodiversity, abundance and community structure of the benthic macrofauna were described. Annelida (42.1% of total abundance; 137 species) and Arthropoda (20.6%; 162 species) were, respectively, the most abundant and the most species-rich Phyla among the 342 taxa identified during this study. Multivariate analyses showed significant differences between and within canyons and between canyons and open slope assemblages. At their upper section, canyons supported higher macrofauna abundance but slightly lower biodiversity than the adjacent slopes at similar depth. In all canyons abundance reached the highest value in the middle section and the lowest in the upper section, with marked fluctuations in Nazaré (474-4599 ind. m

Sediment community responses to marine vs. terrigenous organic matter in a submarine canyon

“…Abundances recorded in the present study were comparable with those observed by Cunha et al (2011) Witte et al, 2003a;Sweetman and Witte, 2008b). Benthic macrofaunal assemblages exhibited conspicuous differences between the Whittard canyons eastern and western branches.…”

“…Canyon sediments receive increased POM inputs via both vertical transport, through the water column, and lateral transport, through slope processes. Consequently, canyons may support higher bacterial and faunal densities than surrounding bathyal and abyssal sediments (Vetter and Dayton, 1998;Duineveld et al, 2001;EscobarBriones et al, 2008;De Leo et al, 2010;Cunha et al, 2011). In the Whittard Canyon (Northeast Atlantic), Duineveld et al (2001) report enhanced sediment community oxygen consumption (SCOC) within canyon sediments.…”

Trophic state of benthic deep-sea ecosystems from two different continental margins off Iberia

“…Such trophic characteristics allow us to hypothesize, according to the optimal foraging theory (McArthur and Pianka, 1966), that benthic detritus feeders inhabiting the Nazarè canyon may have relevant energetic/metabolic advantages compared to those inhabiting the open slopes. These findings provide additional support to explain why higher meiofaunal and macrofaunal standing stocks are reported in the Nazarè canyon compared with the adjacent open slopes at similar depths (Ingels et al, 2009;Cunha et al, 2011). Moreover, the enhanced nutritional value of bioavailable organic detritus with increasing water depth can contribute, along with other factors previously suggested (e.g., level of physical disturbance and spatial heterogeneity), to justify the distribution patterns of macrofaunal abundances, i.e.…”

Effect of continental shelf canyons on phytoplankton biomass and community composition along the western Antarctic Peninsula

“…Allen et al 2001, Ryan et al 2005 and subsequent distribution and diversity of higher trophic levels (Cunha et al 2011, Fanelli et al 2011. Canyon dynamics along some regions of the Antarctic continental margin may be affected both by latitudinal trends in atmospheric warming and sea ice loss, as well as regional shifts in winds and ocean circulation.…”