Biological structures exert a major influence on species diversity at both local and regional scales on deep continental margins. Some organisms use other species as substrates for attachment, shelter, feeding or parasitism, but there may also be Mutual benefits from the association. Here, we highlight the structural attributes and biotic effects of the habitats that corals, sea pens, sponges and xenophyophores offer other organisms. The environmental setting of the biological structures influences their species composition. The importance of benthic species as substrates seems to increase with depth as the complexity of the surrounding geological substrate and food supply decline. There are marked differences in the degree of mutualistic relationships between habitat-forming taxa. This is especially evident for scleractinian corals, which have high numbers of facultative associates (commensals) and few obligate associates (mutualists), and gorgonians, with their few commensals and many obligate associates. Size, flexibility and architectural complexity of the habitat-forming organism are positively related to species diversity for both sessile and mobile species. This is mainly evident for commensal species sharing a facultative relationship with their host. Habitat complexity is enhanced by the architecture of biological structures, as well as by biological interactions. Colony morphology has a great influence on feeding efficiency for suspension feeders. Suspension feeding, habitat-forming organisms modify the environment to optimize their food uptake. This environmental advantage is also passed on to associated filter-feeding species. These effects are poorly understood but represent key points for understanding ecosystems and biodiversity on continental margins. In this paper we explore the contributions of organisms and the biotic structures they create (rather than physical modifications) to habitat heterogeneity and diversity on the deep continental margins

The oceanic abyss (depths greater than 3000 m), one of the largest environments on the planet, is characterized by absence of solar light, high pressures and remoteness from surface food supply necessitating special molecular, physiological, behavioural and ecological adaptations of organisms that live there. Sampling by trawl, baited hooks and cameras we show that the Chondrichthyes (sharks, rays and chimaeras) are absent from, or very rare in this region. Analysis of a global data set shows a trend of rapid disappearance of chondrichthyan species with depth when compared with bony fishes. Sharks, apparently well adapted to life at high pressures are conspicuous on slopes down to 2000 m including scavenging at food falls such as dead whales. We propose that they are excluded from the abyss by high-energy demand, including an oil-rich liver for buoyancy, which cannot be sustained in extreme oligotrophic conditions. Sharks are apparently confined to ca 30% of the total ocean and distribution of many species is fragmented around sea mounts, ocean ridges and ocean margins. All populations are therefore within reach of human fisheries, and there is no hidden reserve of chondrichthyan biomass or biodiversity in the deep sea. Sharks may be more vulnerable to over-exploitation than previously thought.

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Scavenging fishes of the Mid-Atlantic Ridge (MAR) were investigated using a baited autonomous lander equipped with a time-lapse camera between 924 and 3420 m water depth along 3 east -west transects at 42, 51 and 53°N across the MAR. We photographed 22 taxa at bait. Community structure analysis revealed 3 main assemblages, shallow (924 to 1198 m), intermediate (1569 to 2355 m) and deep (2869 to 3420 m), dominated by 3 species, Synaphobranchus kaupii, Antimora rostrata and Coryphaenoides (Nematonurus) armatus, respectively. Abyssal species in the axial valley region were C. armatus, Histiobranchus bathybius and Spectrunculus sp. Compared with continental margin regions A. rostrata were abundant and grew to a large size in the 2 northern transects, whereas S. kaupii were reduced in abundance and maximum depth of occurrence. The size, abundance and depth distribution of C. armatus was consistent with the hypothesis that these fish are part of a population mixing freely across the deep North Atlantic Basin. Temperature and latitude influenced distribution. (1) Five taxa were found only in the southern transect: Pseudotriakis microdon, Centroscymnus coelolepis, Simenchelys parasitica, Anguilliformes sp. and Lepidion 1 sp.

Deep-ocean animals remain poorly understood compared to their shallow-water relatives, mainly because of the great cost and difficulty involved in obtaining reliable ecological data. This is a serious issue, as exploitation of deep-water resources progresses without sufficient data being available to assess its risks and impacts. First described almost 40 yr ago, the use of baited cameras was pioneered by deep-sea biologists and is now a widely used technique for assessing patterns of animal behavior, abundance, and biodiversity. The technique provides a non-destructive and cost-effective means of collecting data, where other techniques such as trawling are difficult or impractical. This review describes the evolution of baited camera techniques in deep-sea research from the early deployments, through recent programs to investigate trends in animal distribution with depth, latitude, and ocean basin. The techniques used for imaging, baiting, and analysis are synthesized, with special consideration of the modeling techniques used in assessing animal abundance and biomass.

The ichthyofauna of ocean margin regions is characterised by a succession of different species occurring at different depths. This study was aimed at determining whether the resultant pattern of species richness with depth is a consequence of local factors in a given region or whether it simply reflects the global pattern of fish species distribution in the oceans. Along the ocean margin of the temperate NE Atlantic Ocean in the Porcupine Seabight and Abyssal Plain region, 48°-53°N, a total of 108 demersal fish species were identified from 187 trawls at depths from 240 to 4865 m. Fitting of species accumulation curves predicted an asymptote of 120, indicating that the fauna is 90% described. Baited cameras detected 22 scavenging species with a predicted asymptote of 24 species. Scavenging species represented a constant 22.7% (SD 3.5%) of the total species richness throughout the depth range studied. Species richness per trawl varied between a maximum of 16 at 1600 m and 4 on the abyssal plain > 4000 m with no significant influence of sea floor slope (a measure of topographic heterogeneity). Total species richness was 48 at 1600 m and 10 on the abyssal plain. There is a clear transition between slope species above 3000 m and abyssal species below. The depth at which peak species richness occurs (1100-2000 m) coincides with the depth of the permanent thermocline, presence of Mediterranean overflow water (MOW), seasonally strong currents, resuspension of particulate matter, high biomass of benthic filter feeders and pelagic biomass impinging on the slope. We suggest that these factors increase habitat and resource heterogeneity, thus supporting a wider range of fish species. The local pattern of species richness was compared with the global distribution of maximum depths of marine fish species from FishBase. Globally all three Classes of fishes, Agnatha, Chondrichthyes and Osteichthyes, showed a logarithmic decrease in species with depth, with the deepest observed species in each class occurring at 3003 m, 4156 m and 8370 m, respectively. In contrast, the local distribution of species maximum depths is idiosyncratic with a mean of 16.6 species maxima per 500 m at 1000-3000 m depth followed by three species per 500 m at 3500-4000 m and 11 species per 500 m at 5000 m. It is concluded that global patterns of species richness, as a source of recruitment, exert a weak influence on local patterns of species richness. Rather, global species richness is the sum of numerous regional and local patterns, each determined by characteristic environmental conditions.

Burkholderia cepacia has recently been recognized as an important pathogen in chronic lung disease in patients with cystic fibrosis (CF). Because of the social, psychological, and medical implications of the isolation of B. cepacia from CF patients, accurate identification of this organism is essential. We compared the accuracies of four commercial systems developed for the identification of nonfermenting, gram-negative bacilli with that of conventional biochemical testing for 150 nonfermenters including 58 isolates of B. cepacia recovered from respiratory secretions from CF patients. The accuracies of the four systems for identifying all nonfermenters ranged from 57 to 80%, with the RapID NF Plus system being most accurate. The accuracies of these systems for identifying B. cepacia ranged from 43 to 86%, with the Remel system being most accurate. Depending on the commercial system, from two to seven isolates were misidentified as B. cepacia. The relatively poor performance of the commercial systems requires that identification of certain nonfermenters be confirmed by conventional biochemical testing. These organisms include B. cepacia, Burkholderia sp. other than B. cepacia, and infrequently encountered environmental species (Pseudomonas and Flavobacterium species). In addition, conventional biochemical testing should be done if a commercial system fails to assign an identification to an organism. Confirmatory testing should preferably be performed by a reference laboratory with experience in working with organisms isolated from CF patients.

The addition of iron to high-nutrient low-chlorophyll (HNLC) oceanic waters stimulates phytoplankton, leading to greater primary production. Large-scale artificial ocean iron fertilization (OIF) has been proposed as a means of mitigating anthropogenic atmospheric CO2, but its impacts on ocean ecosystems below the photic zone are unknown. Natural OIF, through the addition of iron leached from volcanic islands, has been shown to enhance primary productivity and carbon export and so can be used to study the effects of OIF on life in the ocean. We compared two closely-located deep-sea sites (∼400 km apart and both at ∼4200 m water depth) to the East (naturally iron fertilized; +Fe) and South (HNLC) of the Crozet Islands in the southern Indian Ocean. Our results suggest that long-term geo-engineering of surface oceanic waters via artificial OIF would lead to significant changes in deep-sea ecosystems. We found that the +Fe area had greater supplies of organic matter inputs to the seafloor, including polyunsaturated fatty acid and carotenoid nutrients. The +Fe site also had greater densities and biomasses of large deep-sea animals with lower levels of evenness in community structuring. The species composition was also very different, with the +Fe site showing similarities to eutrophic sites in other ocean basins. Moreover, major differences occurred in the taxa at the +Fe and HNLC sites revealing the crucial role that surface oceanic conditions play in changing and structuring deep-sea benthic communities.