Deep-sea demersal ichthyofauna of contrasting localities: Mid-Atlantic Ridge, Nazaré Canyon (North Atlantic Ocean) and Crozet Plateau (Southern Indian Ocean), with special reference to the abyssal grenadier, Coryphaenoides (Nematonurus) armatus (Hector, 1875)
King, Nicola J 2006
University of Aberdeen (U.K.), 401 pp.
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The first observations of deep-demersal scavenging fishes are presented from three regions of the world’s oceans with contrasting overlying productivity; the Mid-Atlantic Ridge (MAR) and Nazaré Canyon, Northeast Atlantic Ocean, and the Crozet Plateau, Southern Indian Ocean. The MAR is the most significant topographic feature of the North Atlantic Ocean and is under the influence of a sub-polar front with increased productivity to the north. Twenty-two taxa were photographed at bait; 14 at 42 deg N and 17 over two transects at 51 and 53deg N respectively. Decreases in biodiversity across the 51 deg N transect compared to the 42 and 53 deg N transects, support the hypothesis that 48 deg N - 52 deg N, is a region of faunal change in demersal fish assemblages in the North Atlantic Ocean.

The Nazaré Canyon is a large submarine canyon intersecting the Iberian continental margin which receives high levels of organic matter from local upwelling and terrigenous sources. Nine fish species were photographed at the baited ROBIO lander at all depths within the canyon. It is hypothesized that the increased organic input positively influences benthic food supply within the canyon, supporting elevated populations of scavenging fauna.

The Crozet Plateau is situated in the southern reaches of the Indian Ocean, where the abyssal seafloor (ca. 4200 m) receives differing levels of surface-derived organic enrichment. Demersal ichthyofaunal biodiversity, abundance and biomass were sampled by trawl at a eutrophic site (M5) and oligotrophic site (M6). Demersal fish species richness, abundance and biomass were greater at M5 compared to M6, and dominated by Macrouridae. However, overall results were not significant, leading to the conclusion that the rattail fishes are transient between sites. Six species new to science were collected and are described herein (one Ophidiid, three Liparidae and two Zoarcidae), as well as several other rare specimens of Ophidiid and Zoarcid.

More information is avilable at http://www.oceanlab.abdn.ac.uk/staff/king.shtml