Benthic Deep-sea Research Articles

Miles down for lunch: deep-sea in situ observations of Arctic finned octopods Cirroteuthis muelleri suggest pelagic-benthic feeding migration.

Deep-sea cephalopods are diverse, abundant, and poorly understood. The Cirrata are gelatinous finned octopods and among the deepest-living cephalopods ever recorded. Their natural feeding behaviour remains undocumented. During deep-sea surveys in the Arctic, we observed Cirroteuthis muelleri. Octopods were encountered with their web spread wide, motionless and drifting in the water column 500-2600 m from the seafloor. Individuals of C. muelleri were also repeatedly observed on the seafloor where they exhibited a repeated, behavioural sequence interpreted as feeding. The sequence (11-21 s) consisted of arm web spreading, enveloping and retreating. Prey capture happened during the enveloping phase and lasted 5-49 s. Numerous traces of feeding activity were also observed on the seafloor. The utilization of the water column for drifting and the deep seafloor for feeding is a novel migration behaviour for cephalopods, but known from gelatinous fishes and holothurians. By benthic feeding, the octopods benefit from the enhanced nutrient availability on the seafloor. Drifting in the water column may be an energetically efficient way of transportation while simultaneously avoiding seafloor-associated predators. In situ observations are indispensable to discover the behaviour of abundant megafauna, and the energetic coupling between the pelagic and benthic deep sea.

Local Environmental Conditions Promote High Turnover Diversity of Benthic Deep-Sea Fungi in the Ross Sea (Antarctica).

Fungi are a ubiquitous component of marine systems, but their quantitative relevance, biodiversity and ecological role in benthic deep-sea ecosystems remain largely unexplored. In this study, we investigated fungal abundance, diversity and assemblage composition in two benthic deep-sea sites of the Ross Sea (Southern Ocean, Antarctica), characterized by different environmental conditions (i.e., temperature, salinity, trophic availability). Our results indicate that fungal abundance (estimated as the number of 18S rDNA copies g−1) varied by almost one order of magnitude between the two benthic sites, consistently with changes in sediment characteristics and trophic availability. The highest fungal richness (in terms of Amplicon Sequence Variants−ASVs) was encountered in the sediments characterized by the highest organic matter content, indicating potential control of trophic availability on fungal diversity. The composition of fungal assemblages was highly diverse between sites and within each site (similarity less than 10%), suggesting that differences in environmental and ecological characteristics occurring even at a small spatial scale can promote high turnover diversity. Overall, this study provides new insights on the factors influencing the abundance and diversity of benthic deep-sea fungi inhabiting the Ross Sea, and also paves the way for a better understanding of the potential responses of benthic deep-sea fungi inhabiting Antarctic ecosystems in light of current and future climate changes.

Development of a life cycle impact assessment framework accounting for biodiversity in deep seafloor ecosystems: A case study on the Clarion Clipperton Fracture Zone

The transformation of ecosystems is known to be a major driver of biodiversity loss. Consequently, supporting tools such as life cycle assessment methods (LCA) include this aspect in the evaluation of a product's environmental performance. Such methods consist of quantifying input and output flows to assess their specific contributions to impact categories. Therefore, land occupation and transformation are considered as inputs to assess biodiversity impacts amongst others. However, the modelling of biodiversity impact in deep seafloor ecosystems is still lacking in LCA. Most of the LCA methods focus on terrestrial biodiversity and none of them can be transposed to benthic deep sea because of knowledge gaps. This manuscript proposes a LCA framework to assess biodiversity impacts in deep seafloor ecosystems. The framework builds upon the existing methods accounting for biodiversity impacts in terrestrial and coastal habitats. A two-step approach is proposed, assessing impacts on regional and on global biodiversity. While the evaluation of regional biodiversity impacts relies only on the benthic communities' response to disturbance, the global perspective considers ecosystem vulnerability and scarcity. Those provide additional perspective for the comparison of impacts occurring in different ecosystems. The framework is operationalised to a case study for deep-sea mining in the Clarion Clipperton Fractures Zone (CCZ). Through the large variety of data sources needed to run the impact evaluation modelling, the framework shows consistency and manages the existing limitations in the understanding of deep seafloor ecosystems, although limitations for its application in the CCZ were observed mainly due to the lack of finer scaled habitat maps and data on connectivity. With growing interest for commercial activities in the deep sea and hence, increased environmental research, this work is a first attempt for the implementation of LCA methods to deep-sea products.

<strong>New reports of echinoderms on the Caribbean continental slope of central America</strong>

The Caribbean is considered a unique biogeographic region that represents an important hotspot of marine diversity in the Atlantic Ocean. The Caribbean Continental Slope of Central America (CCCA) is a largely unexplored area that exhibits a variety of habitats. Among this unstudied biodiversity, special importance has been given to the benthic communities associated with deep bottoms, a diverse group that plays a major role in the ocean carbon cycling and nutrient flux. Echinoderms are one of the main benthic deep sea taxa, in which Holothuroidea is the globally dominant class. We present the results from the first exploratory fishing survey campaign on the CCCA, done under the regional coordination of OSPESCA (Central America Fisheries and Aquaculture Organization) on board of the R/V Miguel Oliver in January 2011. Data was collected from a total of 96 trawls arranged in 25 transects that started in Panama and finished in Belize. A Lofoten bottom trawling net was dragged for 30 min between 0 to 1500m depth. The major component of the total invertebrate catch was Holothuroidea with a biomass of 593 kg (16.49% of the total) and represented by seven species. The following are new reports for the Caribbean: Bathyplotes natans in Honduras and Guatemala, Bentothuria funebris in Panama, Benthodytes sanguinolenta in Panama, Costa Rica, Nicaragua and Belize; Hansenothuria sp. in Panama, Costa Rica and Honduras. Paroriza pallens extends its distribution to Panama, Costa Rica, Nicaragua and Honduras, Zygothuria lactea its reported in Panama. We also present the first records of the crinoid Neocomatella pulchella in Honduras, theasteroid Cheiraster (Cheiraster) planusin Panama, and, for Costa Rica (Asteroidea: Doraster constellatus and Echinoidea: Clypeaster euclastus).Holothurians are the predominant invertebrate fauna in terms of biomass in the entire region of the CCCA. These findings suggest that CCCA presents a high echinoderm biodiversity and also supports the ecoregional variation theory. We report higher echinoderm biomass (75%) in the Southwestern Caribbean compared to Western Caribbean ecoregion. The information presented in this paper establishes the baseline information of echinoderms depth fauna in the Caribbean of Central America, and opens new opportunities for future research.

From virus isolation to metagenome generation for investigating viral diversity in deep-sea sediments

Viruses are the most abundant and, likely, one of the most diverse biological components in the oceans. By infecting their hosts, they play key roles in biogeochemical cycles and ecosystem functioning at a global scale. The ocean interior hosts most of the microbial life, and, despite deep-sea sediments represent the main repository of this component and the largest biome on Earth, viral diversity in these ecosystems remains almost completely unknown. We compared a physical-chemical procedure and a previously published sediment washing-based procedure for isolating viruses from benthic deep-sea ecosystems to generate viromes through high-throughput sequencing. The procedure based on a physical-chemical dislodgment of viral particles from the sediments, followed by vacuum filtration was much more efficient allowing us to recover >85% of the extractable viruses. By using this procedure, a high fraction of viral DNA was recovered and new viromes from different benthic deep-sea sites were generated. Such viromes were diversified in terms of both viral families and putative functions. Overall, the results presented here provide new insights for evaluating benthic deep-sea viral diversity through metagenomic analyses, and reveal that deep-sea sediments are a hot spot of novel viral genotypes and functions.

Response of Bacterial Communities to Different Detritus Compositions in Arctic Deep-Sea Sediments.

Benthic deep-sea communities are largely dependent on particle flux from surface waters. In the Arctic Ocean, environmental changes occur more rapidly than in other ocean regions, and have major effects on the export of organic matter to the deep sea. Because bacteria constitute the majority of deep-sea benthic biomass and influence global element cycles, it is important to better understand how changes in organic matter input will affect bacterial communities at the Arctic seafloor. In a multidisciplinary ex situ experiment, benthic bacterial deep-sea communities from the Long-Term Ecological Research Observatory HAUSGARTEN were supplemented with different types of habitat-related detritus (chitin, Arctic algae) and incubated for 23 days under in situ conditions. Chitin addition caused strong changes in community activity, while community structure remained similar to unfed control incubations. In contrast, the addition of phytodetritus resulted in strong changes in community composition, accompanied by increased community activity, indicating the need for adaptation in these treatments. High-throughput sequencing of the 16S rRNA gene and 16S rRNA revealed distinct taxonomic groups of potentially fast-growing, opportunistic bacteria in the different detritus treatments. Compared to the unfed control, Colwelliaceae, Psychromonadaceae, and Oceanospirillaceae increased in relative abundance in the chitin treatment, whereas Flavobacteriaceae, Marinilabiaceae, and Pseudoalteromonadaceae increased in the phytodetritus treatments. Hence, these groups may constitute indicator taxa for the different organic matter sources at this study site. In summary, differences in community structure and in the uptake and remineralization of carbon in the different treatments suggest an effect of organic matter quality on bacterial diversity as well as on carbon turnover at the seafloor, an important feedback mechanism to be considered in future climate change scenarios.

Diversity and abundance of deep-sea Isopoda along the Southern Polar Front: Results from the SYSTCO I and II expeditions

For the investigation of the diversity and composition of deep-sea Isopoda in the Polar Front of the Southern Ocean two expeditions were performed, ANtartic benthic DEEP-sea biodiversity: colonization history and recent community patterns–SYSTem COupling (ANDEEP–SYSTCO I, 2007/2008) and SYSTCO II (2012). Samples were taken in the Atlantic sector of the Southern Polar Front (52°S) within a depth range between 2752 and 4327m using an epibenthic sledge. From nine stations, located in four different geographic areas, a total of 107 species from 476 specimens were identified, 99% belonged to the suborder Asellota. Haploniscidae was the most dominant family in terms of abundance, followed by Munnopsidae and Desmosomatidae. However, Munnopsidae were the most diverse followed by Desmosomatidae and Haploniscidae. The majority of species (53%) did not occur frequently indicating a patchy distribution; only one species, Haploniscus spinifer Hansen, 1916, was found at almost all stations comprising more than 10% of all sampled specimens. Isopod abundance was generally low in the Polar Front compared to other regions of the Southern Ocean, like the Weddell Sea. Diversity strongly varied between stations even within the same sampling area, it was highest around a depth of 3000m with 48 species found at station 13–16 at 0°E. Surface chl a concentration, received from satellite images as a measure for food supply, was compared with isopod abundance and diversity, however, no clear pattern could be observed. Analysis of the species composition of Isopoda revealed in general terms that deep-sea stations within the same depth range build one cluster. Also the sampling year, the geographic area or salinity turned out to be possible factors affecting species composition. The deep-sea area along the Southern Polar Front is characterized by low numbers of specimens but shelters a relatively high level of isopod diversity with species also known from other regions of the Atlantic.

Dark inorganic carbon fixation sustains the functioning of benthic deep‐sea ecosystems

Previous studies have provided evidence that dark inorganic carbon fixation is an important process for the functioning of the ocean interior. However, its quantitative relevance and ecological significance in benthic deep‐sea ecosystems remain unknown. We investigated the rates of inorganic carbon fixation together with prokaryotic abundance, biomass, assemblage composition, and heterotrophic carbon production in surface sediments of different benthic deep‐sea systems along the Iberian margin (northeastern Atlantic Ocean) and in the Mediterranean Sea. Inorganic carbon fixation rates in these surface deep‐sea sediments did not show clear depth‐related patterns, and, on average, they accounted for 19% of the total heterotrophic biomass production. The incorporation rates of inorganic carbon were significantly related to the abundance of total Archaea (as determined by catalyzed reporter deposition fluorescence in situ hybridization) and completely inhibited using an inhibitor of archaeal metabolism, N1‐guanyl‐1,7‐diaminoheptane. This suggests a major role of the archaeal assemblages in inorganic carbon fixation. We also show that benthic archaeal assemblages contribute approximately 25% of the total 3H‐leucine incorporation. Inorganic carbon fixation in surface deep‐sea sediments appears to be dependent not only upon chemosynthetic processes but also on heterotrophic/mixotrophic metabolism, as suggested by estimates of the chemolithotrophic energy requirements and the enhanced inorganic carbon fixation due to the increase in the availability of organic trophic resources. Overall, our data suggest that archaeal assemblages of surface deep‐sea sediments are responsible for the high rates of inorganic carbon incorporation and thereby sustain the functioning of the food webs as well as influence the carbon cycling of benthic deep‐sea ecosystems.

A new species of Wellsopsyllus (Copepoda, Harpacticoida, Paramesochridae) from the deep Southern Ocean and remarks on its biogeography

The new deep-sea copepod species of the family Paramesochridae (Copepoda, Harpacticoida) presented here was collected during the scientific ANtarctic benthic DEEP-sea biodiversity cruise II (ANDEEP II) to the Weddell Abyssal Plain and western Weddell Sea and the CROZet natural iron bloom and EXport experiment (CROZEX cruise) to the Crozet Isles in the Indian Ocean. The new species has been allocated to the subgenus Wellsopsyllus within the genus Wellsopsyllus Kunz, 1981, based on the 1-segmented endopods and 3-segmented exopods of swimming legs 2–4. Furthermore, the new species shows a 1-segmented exopod of the antenna. Wellsopsyllus (W.) antarcticus sp. n. can be distinguished from its congeners by its small body size, the presence of two setae on the distal segment of the endopod of the first swimming leg, by the very small furcal rami, the extremely reduced endopods of second and third swimming legs, the reduced mandibular palp and maxillula, as well as by the size and armature of the fifth and sixth swimming legs in both sexes. Difficulties of the placement of the new species into a suitable genus show an insufficiency in the present family classification. In the future, a revision of the genus Wellsopsyllus is essential. With its presence in the western Weddell Sea and the Indian Ocean, the new species may have a wide distribution range. Furthermore, it is the first abyssal species of the genus Wellsopsyllus sampled outside of the Scotia Sea.

Is there a distinct continental slope fauna in the Antarctic?

The Antarctic continental slope spans the depths from the shelf break (usually between 500 and 1000 m) to ∼3000 m, is very steep, overlain by ‘warm’ (2–2.5 °C) Circumpolar Deep Water (CDW), and life there is poorly studied. This study investigates whether life on Antarctica’s continental slope is essentially an extension of the shelf or the abyssal fauna, a transition zone between these or clearly distinct in its own right. Using data from several cruises to the Weddell Sea and Scotia Sea, including the ANDEEP (ANtarctic benthic DEEP-sea biodiversity, colonisation history and recent community patterns) I–III, BIOPEARL (BIOdiversity, Phylogeny, Evolution and Adaptive Radiation of Life in Antarctica) 1 and EASIZ (Ecology of the Antarctic Sea Ice Zone) II cruises as well as current databases (SOMBASE, SCAR-MarBIN), four different taxa were selected (i.e. cheilostome bryozoans, isopod and ostracod crustaceans and echinoid echinoderms) and two areas, the Weddell Sea and the Scotia Sea, to examine faunal composition, richness and affinities. The answer has important ramifications to the link between physical oceanography and ecology, and the potential of the slope to act as a refuge and resupply zone to the shelf during glaciations. Benthic samples were collected using Agassiz trawl, epibenthic sledge and Rauschert sled. By bathymetric definition, these data suggest that despite eurybathy in some of the groups examined and apparent similarity of physical conditions in the Antarctic, the shelf, slope and abyssal faunas were clearly separated in the Weddell Sea. However, no such separation of faunas was apparent in the Scotia Sea (except in echinoids). Using a geomorphological definition of the slope, shelf-slope-abyss similarity only changed significantly in the bryozoans. Our results did not support the presence of a homogenous and unique Antarctic slope fauna despite a high number of species being restricted to the slope. However, it remains the case that there may be a unique Antarctic slope fauna, but the paucity of our samples could not demonstrate this in the Scotia Sea. It is very likely that various ecological and evolutionary factors (such as topography, water-mass and sediment characteristics, input of particulate organic carbon (POC) and glaciological history) drive slope distinctness. Isopods showed greatest species richness at slope depths, whereas bryozoans and ostracods were more speciose at shelf depths; however, significance varied across Weddell Sea and Scotia Sea and depending on bathymetric vs. geomorphological definitions. Whilst the slope may harbour some source populations for localised shelf recolonisation, the absence of many shelf species, genera and even families (in a poorly dispersing taxon) from the continental slope indicate that it was not a universal refuge for Antarctic shelf fauna.

Southern Ocean deep-sea biodiversity—From patterns to processes

Abstract The Southern Ocean is characterized by a narrow and deep shelf, an almost isothermal water column and a large area of deep sea surrounding Antarctica. However, knowledge of the deep-sea faunal composition, particularly in the Southern Ocean, is still scarce in comparison with shelf and upper slope environment. For that reason a deep-sea project was devoted to investigate this little-known area of the Southern Ocean. ANDEEP (ANtarctic benthic DEEP-sea biodiversity: colonisation history and recent community patterns) took place in 2002–2005 and provided first insights into the biodiversity and biogeography of Southern Ocean benthic animals from meio- to megafauna. The results with the very general patterns are outlined here. Based on the knowledge on biodiversity patterns gained through ANDEEP, a follow-up project, ANDEEP-SYSTCO (SYSTem COupling), was established in the international polar year in order to investigate the processes driving the biodiversity pattern observed. This expedition took place in 2007/2008 and only preliminary data can be presented at this stage given that the material was available for only a couple of months since the return of R.V. Polarstern. Some key results identified after the SYSTCO expedition are presented.

Deep-sea habitat heterogeneity influence on meiofaunal communities in the Gulf of Guinea

To estimate the degree of spatial heterogeneity of benthic deep-sea communities, we carried out a multiple-scale (from m's to 200 km) investigation in the Congo-Angola margins (Equatorial West African margin, 3150–4800 m) in which we examined the metazoan meiofauna at a variety of habitats along the Congo Channel system and in the associated cold seep. We investigate the structure, density, vertical distribution patterns in the sediment and biomass of meiofaunal communities in the Gulf of Guinea and how they are controlled by hydrologic and biogeochemical processes. The meiofaunal communities in the Gulf of Guinea were shaped by heterogeneous conditions on the margin, and reflect the multiple-scale spatial variability that corresponds with the different identified habitats. The two control sites, located at >100 km away from the canyon, were inhabited by very dense and the most diverse meiobenthic communities. Similar meiobenthic communities inhabited the transition zone between the canyon and the cold seep. Sites located along the Congo Channel were obviously affected by the local high-velocity bottom currents and unstable sedimentary conditions in this active submarine system. Extremely low meiobenthic densities and very low proportions in the most surficial sediment layers provided evidence for recently highly disturbed sediments at these sites. The remote operated vehicle (ROV) Victor 6000 provided images of the cold seep, showing a patchy distribution of several types of patchy distributed megafaunal communities dominated by three key symbiotic taxa (Mytilidae, Vesicomyidae and Siboglinidae). These cold seep sediments were colonised by a unique meiobenthic community, characterised by a high small-scale (m's) patchiness, low species richness and the prominent dominance of two large-sized nematode species: Sabatieria mortenseni, which is a cosmopolitan nematode known from littoral habitats, and an undescribed Desmodora species. The high individual body weight of S. mortenseni and its dominance at the cold seep site resulted in a significantly higher nematode biomass at the seep compared to the surrounding sites. In addition, the vertical nematode profiles, with maximum proportions in subsurficial layers, points to a chemosynthesis-based meiobenthic community in this cold seep, in contrast to the phytodetritus-based communities at the control sites and at the transition zone.

First record and new species of the genus Hebefustis Siebenaller & Hessler, 1977(Isopoda: Asellota: Nannoniscidae) from the deep Weddell Sea Basin

The ANDEEP (ANtarctic benthic DEEP-sea biodiversity, colonisation history and recent community patterns) cruises contributed immensely to the understanding of the deep Southern Ocean biodiversity, and study of the fauna, in particular the isopod crustaceans, which were revealed to be patchily rich. Most of the species found during the three ANDEEP expeditions were not only new to the region but also new to science. In the current paper a new nannoniscid species, Hebefustis clareolithis sp. nov., is described from the deep Weddell Sea Basin (Southern Ocean). Specimens of the new species were sampled during ANDEEP III in Antarctic summer 2004/05 and represent the first Southern Ocean record of the genus Hebefustis Siebenaller & Hessler, 1977. The new species closely resembles Hebefustis cornutus Siebenaller & Hessler, 1977 but can be distinguished from the latter by the number of flagellar articles of the female antenna, the shape of pleopod 1 and pleotelson in male. A key to the species in the genus Hebefustis is provided.

Recent deep-water sedimentation, trace metal and radioisotope geochemistry across the Southern Ocean and Northern Weddell Sea, Antarctica

Abstract A wide variety of deep-water depositional environments were examined across 12 sampling stations in the Southern Ocean and northern Weddell Sea, Antarctica in order to provide a depositional context for the benthic biodiversity studies of ANDEEP (Antarctic Benthic Deep-Sea Biodiversity: colonisation history and recent community patterns). Here we present a diverse dataset comprising sub-bottom profiles, seabed photographs, sediment profile images, and box and multicore samples in order to investigate the recent depositional environments across the region. The sediments were investigated using texture, structure, trace metal (Mn, Fe, U, Mo, Ba, and Pb), stable (206Pb/207Pb) and radionuclide (excess 210Pb) isotopes. The sediments of the Agulhas Basin are interpreted as siliceous pelagites, the product of enhanced surface productivity. The eastern Weddell continental rise is characterised by diverse depositional environments with hemipelagic, turbiditic and contouritic sedimentation. In contrast, the northern Weddell Abyssal Plain is dominated by hemipelagites with fine-grained turbidites. A single sampling station from the central Powell Basin contained hemipelagites and a fine-grained turbidite. A core from the central Bransfield Strait recovered hemipelagites with a silt turbidite. The seabed photographs display a seabed dominated by biogenic mud balls formed by cirratulid polychaetes. Trace metal, Pb-isotope, and excess 210Pb data all reveal the central Bransfield Strait to be a region of enhanced productivity with a mass accumulation rate of 0.073 g/cm2. Two stations in the Bellingshausen Sea recovered hemipelagites and turbidites. Mn, Fe and Mo data suggest a degradation of organic matter in the sediments leading to redox cycling.

Slope and deep-sea abundance across scales: Southern Ocean isopods show how complex the deep sea can be

How animals are distributed in the world's largest surface environment, the deep sea, is poorly understood. The ANDEEP (ANtarctic benthic DEEP-sea biodiversity, colonisation history and recent community patterns) III cruise probed richness and abundance of one group, peracarid crustaceans (isopods, amphipods, cumaceans, tanaidaceans, mysidaceans), as a model of deep-sea fauna across Southern Ocean (SO) sites. Analysis of samples from the ANDEEP cruises reveals SO isopods to be highly abundant, rich and endemic as many other taxa in the region are known to be. Samples taken across three spatial scales include sites tens, hundreds and thousands of kilometers apart, sites stretching from the Southern Cape Basin (South Atlantic) to continental Antarctica and including depths from 1030 to 5000 m. Across these spatial scales we investigated ecological success (abundance) of peracarids at order, family, and species levels. Remarkably no significant relationship was found between abundance and spatial scale at any taxonomic level. That is, the variability in abundance at major regional scale is no different to that across just tens of kilometres. Most taxa were represented in only a few samples, but we suggest most inhabitants of the deep Weddell Sea environment to be very patchy rather than rare. Separate plots of family, genus, and species abundance by sample number revealed this to be true—nearly all genera and species are an order of magnitude more abundant than ‘background’ levels in just one or two samples. Our isopod and amphipod samples reveal the Atlantic sector of the SO, one of the most dynamic and important regions influencing the global deep-sea environment, to be highly complex. Our study suggests that, at least with regard to the study taxa and area, the typical comparisons of regions that are made by ecologists miss the scale at which crucial ecological variability happens. Even without ice scours creating topographical complexity (as on the shelf) the deep Weddell Sea is clearly complex at scales smaller than that measured to date.

Deep-sea isopod biodiversity, abundance, and endemism in the Atlantic sector of the Southern Ocean—Results from the ANDEEP I–III expeditions

Abstract Three expeditions were performed in the framework of ANDEEP (ANtarctic benthic DEEP-sea biodiversity, colonisation history and recent community patterns) in order to understand the Southern Ocean (SO) biodiversity of the Isopoda and to investigate faunal connections with other deep-sea areas in the world oceans. We sampled mainly in the Atlantic sector of the SO (Drake Passage along the Shackleton Fracture Zone, off Elephant Island, in the South Shetland Islands area, in the northwestern Weddell Sea, and at the South Sandwich Islands), but also took two stations in each Bellingshausen Sea and Cape Basin. In total, three expeditions yielded 13,046 specimens of Isopoda. During ANDEEP I–II 5525 specimens and 317 species of Isopoda were sampled, and 7521 specimens and 496 species were discriminated from the ANDEEP III material. Overall, Isopoda comprised 35% of all Peracarida sampled, and we identified 674 isopod species from the 40 deep SO stations. Eighty-nine of these species (13%) were known, the others (585 species) were new to the area, and most of these were new to science, 43 genera being recorded for the first time. Asellota comprised 97% of all ANDEEP Isopoda, and Munnopsidae were the most dominant family, followed by the Desmosomatidae, Haploniscidae, and Ischnomesidae. To our present knowledge 87% of the SO deep-sea Isopoda are apparently “endemic”. Most species did not occur frequently in the samples. Abundance was higher at the shallower ANDEEP stations and highest in the Powell Basin at station 133, and generally decreased with increasing depth. Species richness was highest with 92 species at the bathyal station 80-9 in 3100 m off Kapp Norvegia, in general, species richness was highest at around 3000 m depth with 216 species found at all ANDEEP stations, and 92 species sampled at a single station in 3100 m depth. The cluster analysis of the isopod composition from ANDEEP revealed in general terms that the abyssal Weddell-Sea stations build one cluster. Depth turned out to be the most important abiotic factor for the species composition reported. Most of the species frequently occurring at the abyssal stations are Munnopsidae, which can swim. The SO deep sea differs in faunal composition from the shelf, and few isopod species occur at many stations, while most species only occur at few. The reasons for these findings are unknown. Future studies should focus on the functional role of the frequent species of the SO deep-sea ecosystem and food-web.

Thoughts on controls on evolution and dispersal of benthos in the Magellan-Scotia Sea region: a workshop proposal

The Scotia Arc and the Scotia Sea comprise a geologically young feature of the Earth’s surface that evolved over the last 40 million years (Ma) or so, between the southern tip of South America and the northern tip of the Antarctic Peninsula. With the notable exception of the much younger South Sandwich Islands, the islands, banks and seamounts of the arc represent dispersed fragments of a previous continental link between southern South America (Magellan region) and the Antarctic Peninsula. The benthic marine shelf faunas of the region are the focus of the IBMANT (Investigacion Biolologica Marina en Magallanes relacionada con la Antartida) programme, and those of the surrounding oceanic deeps are the focus of ANDEEP (Antarctic Benthic Deep-Sea Biodiversity). Elucidating the potential relationships between the faunas of the region and the profound geographical, oceanographic and climatic changes undergone by the region in later Cenozoic time is hampered by significant unknowns in the geological history, the expense of further geoscientific exploration to fill these, and a general lack of communication between the biological and geological science communities. It is suggested that the time is opportune for a truly multidisciplinary workshop at which all the involved science communities have much to gain from the others.

Trophic Structure of One Deep-sea Benthic Fish Community in the Eastern Canadian Arctic: Application of Food, Parasites and Multivariate Analysis

As new arctic marine fisheries develop there is need for a comprehensive ecosystem approach to long-term management. This approach recognizes the importance of community interactions such as food web structure and trophic patterns. We determined whether hierarchical clustering (guild formation) is an effective method of trophic evaluation in deep-sea Artic fish communities using stomach content and parasite data with size class, and evaluated the application of endohelminth communities (parasite species transmitted in the food) as indicators of trophic status. Cluster analysis using food group abundance with size class of fish revealed the presence of 11 guilds within the community, however the same analysis using parasite data showed little correlation between food and parasites. Redundancy analysis (RDA) within the 11 guilds also revealed no significant correlations between food group and parasite abundance suggesting that this type of ordination is not suited for environments containing mainly generalist feeders. RDA of individual taxa without a priori guild designation found that taxa in benthic deep-sea communities are defined by their ability to exploit prey species in more than one habitat zone. Benthic fish species were significantly correlated with benthic food groups and parasites that utilize benthic intermediate hosts whereas benthopelagic–pelagic species fed on a higher diversity of prey species and were infected by a larger number of non-host specific parasites. Eigenanalysis and Monte Carlo results showed that parasites and food groups are highly correlated, indicating that parasite community analysis is an effective tool for predicting feeding strategies in Arctic marine environments. It also suggests that in most cases endoparasite infections alone could be used for trophic evaluation in the absence of stomach content data.

Diversity of Southern Ocean deep-sea Isopoda (Crustacea, Malacostraca) — a comparison with shelf data

Samples were taken during the expeditions ANDEEP I & II (ANT XIX/3-4) (ANtarctic benthic DEEP-sea biodiversity, colonisation history and recent community patterns) with RV Polarstern for the analysis of the Southern Ocean (SO) deep-sea isopod biodiversity in the Drake Passage, off Elephant Island, along the South Shetland Islands, in the northwestern Weddell Sea, and at the South Sandwich Islands. In total 5525 specimens of Isopoda were sampled and 317 species were discriminated. Isopoda were the most abundant peracarid taxon, with 38% of all Peracarida, 98% of the Isopoda belonging to the suborder Asellota. Species richness was highest in the northwestern Weddell Sea; diversity and evenness were relatively high at all stations. The Munnopsididae were the most dominant isopod family, with 61% of the specimens, 118 species divided among 28 genera; the Haploniscidae comprised 15% of all isopods with 36 species from four genera, followed by the Ischnomesidae with 7% and 30 species from five genera. The families Desmosomatidae, Macrostylidae and Nannoniscidae comprised 10% of the isopod specimens. The Desmosomatidae were the second most diverse family, with 48 species from 12 genera. Species of the suborder Valvifera or the family Serolidae were much rarer in the SO deep-sea than on the shelf. 141 of isopod species (46% of the total number) were rare, occurring only at one of the 21 epibenthic-sledge stations. A cluster analysis showed no clear relation between isopod communities and geographic area. Depth was the most important factor for differences in isopod community patterns. The species accumulation curve shows that the SO deep sea was not sampled representatively during ANDEEP I & II and further sampling is necessary. The SO deep-sea differs in faunal composition from the shelf.

Introduction to ANDEEP (ANtarctic benthic DEEP-sea biodiversity: colonization history and recent community patterns)—a tribute to Howard L. Sanders

We dedicate the present volume to the late Howard Sanders, who passed away after a long illness on 7 February 2001. When as a young scientist at the Woods Hole Oceanographic Institution he, together with his colleague Bob Hessler and his technical assistant George Hampson, collected and analyzed the first “quantitative” samples of deep-sea benthos (today one would call them semi-quantitative), he may not have had any idea how instrumental the resulting time-stability hypothesis would prove to be for at least four decades of biological deep-sea research. The image of the deep-sea floor being a lifeless desert or, at best, a desolate place harboring a depauperate fauna was shattered when investigations along a transect between Bermuda and Gay Head, a cliff on the island of Martha's Vineyard off Massachusetts, revealed that while densities decreased with depth, species richness actually increased. Since then, many more samples have been collected, our knowledge, limited as it may still be, has increased dramatically, and many new theories and hypotheses have been developed. Nevertheless, the work and personality of Howard Sanders are still something one feels obligated to measure up to. With ANDEEP I and II, we may not have entered as much of a terra incognita as Sanders and colleagues did 40 years ago, but our excitement was certainly comparable. We sincerely hope Howard would approve if he could hold this volume in his hands.