RRS Challenger Cruise 142, 19 Apr-19 May 1999. Temporal and spatial variability of benthic communities on the Porcupine Abyssal Plain and in the Porcupine Seabight

RRS Challenger Cruise 142 aimed to study 1) long-term change in abyssal benthic communities (4850m, Porcupine Abyssal Plain) and 2) coral communities on carbonate mounds (c. 800m, Porcupine Seabight).Sampling on the first leg was focussed at a central locality 48°50’N, 16°30’W) on the Porcupine Abyssal Plain. This locality had been sampled on 9 separate cruises over a 9-year period (1989-1998). A radical change in the composition of the benthic fauna had occurred in recent years and this cruise aimed to follow further long-term change in the benthic fauna and sediment biogeochemistry. In addition, in order to set the results from this central locality in a basin-wide context, further sampling was undertaken across the Porcupine Abyssal Plain.Sampling on the second leg concentrated on the giant carbonate mounds discovered in recent years on the eastern and northern flanks of the Porcupine Seabight. The mounds had well-developed coral communities. Samples and video of the coral were collected. Other seabed features also noted in sidescan sonar records on previous cruises were imaged as well

RRS Discovery Cruise 248, 07 Jul-10 Aug 2000. A multidisciplinary study of the environment and ecology of deep-water coral ecosystems and associated seabed facies and features (The Darwin Mounds, Porcupine Bank and Porcupine Seabight)

RRS Discovery Cruise 248 aimed to carry out a multidisciplinary study of the environment and ecology of deep-water coral ecosystems and associated seabed features in the northeast Atlantic. The study was primarily focused on the Darwin Mounds area, northern Rockall Trough (59° 49’N, 07° 22’W), but also examined a number of sites in the Porcupine Seabight area. The cruise was divided into two legs (Govan-Stornoway, 8 Jul-21 Jul 2000; Stornoway-Southampton, 22 Jul-10 Aug 2000). Leg 1 focused on the ecology of the Darwin Mounds area, with seabed photographic surveys (SOC SHRIMP system), coring (Box and Multiple cores) and trawling (Agassiz) forming the main activities. Leg 2 began with detailed geological investigations of the Darwin Mounds area, concentrating on piston coring and sidescan sonar surveys. Leg 2 concluded with combined ecological and geological studies of carbonate mound sites on the Porcupine Bank and in the Porcupine Seabight.Observations in the Darwin Mounds area confirmed the common occurrence of deep-water corals on these Mounds. The mounds themselves do not appear to be carbonate formations but may be better characterised as sand volcanoes. Numerous xenophyophores were observed in association with the mounds; however, no live specimens were recovered in any of the samples collected. Sidescan sonar images and seabed photography both suggested that the Darwin Mounds area had been subject to considerable commercial trawling with resultant apparent damage to the deep-water coral ecosystems.The various operations undertaken in the Porcupine Seabight area were also successful in imaging giant carbonate mounds and their associated coral communities with both sidescan sonar and seabed photography, and in recovering biological sample material from these areas. In common with the Darwin Mounds area, the observations made suggested that deep-water fishing impacts on coral ecosystems were also evident in this region

RRS Challenger Cruise 135, 15 Oct-30 Oct 1997. BENGAL: High resolution temporal and spatial study of the BENthic biology and Geochemistry of a north-eastern Atlantic abyssal Locality

Challenger Cruise 135 was the fourth of a series of cruises funded by the European Commission’s Marine Science and Technology III (MAST III) Programme as part of the BENGAL project (MAS3 CT 950018). Sampling commenced in September 1996 to assess changes in benthic systems over a period of one and a half years at a single, abyssal locality in the NE Atlantic (48° 50’N, 16° 30’W). It is hoped that changes within a year (seasonal) and between years (inter-annual) will be detected.Challenger Cruise 135 replaced a longer cruise planned for the vessel Atalante, which had to be cancelled as a result of a strike by the crew of that vessel. Challenger Cruise 135 was planned at extremely short notice with the aim of undertaking a reduced sampling programme and recovering vital moorings that had been in place on the seabed for periods of up to 1 year. Samples of the benthos and overlying water column were collected using a multiple corer, box corer, trawl and CTD. Two activities planned for the Atalante cruise, sampling of benthopelagic fauna using the University of Hamburg MOCNESS net system and photographing the seabed using the Southampton Oceanography Centre WASP system, could not be undertaken

Deep-sea scavenging amphipod assemblages from the submarine canyons of the Western Iberian Peninsula

Submarine canyons have often been identified as hotspots of secondary production with the potential to house distinct faunal assemblages and idiosyncratic ecosystems. Within these deep-sea habitats, assemblages of scavenging fauna play a vital role in reintroducing organic matter from large food falls into the wider deep-sea food chain. Free-fall baited traps were set at different depths within three submarine canyons on the Iberian Margin. Amphipods from the traps were identified to species level and counted. Scavenging amphipod assemblages were compared at different depths within each canyon and between individual canyon systems. Using data from literature, abyssal plain assemblages were compared to submarine canyon assemblages. Samples from canyons were found to contain common abyssal plain species but in greater than expected abundances. It is proposed that this is a result of the high organic carbon input into canyon systems owing to their interception of sediment from the continental shelf and input from associated estuarine systems. Community composition differed significantly between the submarine canyons and abyssal plains. The cause of this difference cannot be attributed to one environmental variable due to the numerous inherent differences between canyons and abyssal plains.<br/

Feeding ecology of deep-sea seastars (Echinodermata : Asteroidea): a pigment biomarker approach

Resource partitioning and utilisation of phytodetritus by the abyssal mud-ingesting seastars Styracaster chuni and Hyphalaster inermis were investigated using pigment biomarker analysis. The chlorophyll and carotenoid pigment composition of the stomach content was examined using high-pressure liquid chromatography. No significant differences were observed between the composition of pigments in the 2 species. Both asteroid species utilise the same phytodetrital resource with no apparent partitioning of that resource. Analysis of specific biomarker pigments together with evidence from previous studies suggest that both species ingest small chlorophytes, cryptomonads, cyanobacteria, coccoliths and diatoms as part of the phytodetrital component of their diet. Phytodetrital material itself is not thought to be an important food source for H. inermis or S. chuni

The trophic and metabolic pathways of foraminifera in the Arabian Sea: evidence from cellular stable isotopes

The Arabian Sea is a region of elevated productivity with the highest globally recorded fluxes of particulate organic matter (POM) to the deep ocean, providing an abundant food source for fauna at the seafloor. However, benthic communities are also strongly influenced by an intense oxygen minimum zone (OMZ), which impinges on the continental slope from 100 to 1000 m water depth. We compared the trophic ecology of foraminifera on the Oman and Pakistan margins of the Arabian Sea (140–3185 m water depth). These two margins are contrasting both in terms of the abundance of sedimentary organic matter and the intensity of the OMZ. Organic carbon concentrations of surficial sediments were higher on the Oman margin (3.32 ± 1.4%) compared to the Pakistan margin (2.45 ± 1.1%) and sedimentary organic matter (SOM) quality estimated from the Hydrogen Index was also higher on the Oman margin (300–400 mg HC mg TOC−1) compared to the Pakistan margin (< 250 mg HC mg TOC−1). The δ13C and δ15N values of sediments were similar on both margins (−20 and 8‰, respectively). Stable isotope analysis (SIA) showed that foraminiferal cells had a wide range of δ13C values (−25.5 to −11.5‰), implying that they utilise multiple food sources; indeed δ13C values varied between depths, foraminiferal types and between the two margins. Foraminifera had broad ranges in δ15N values (−7.8 to 27.3‰). The enriched values suggest that some species may store nitrate to utilise in respiration; this was most notable on the Pakistan margin. Depleted foraminiferal δ15N values, particularly at the Oman margin, may reflect feeding on chemosynthetic bacteria. We suggest that differences in productivity regimes may be responsible for the differences observed in foraminiferal isotopic composition. In addition, at the time of sampling, whole jellyfish carcasses (Crambionella orsini) and a carpet of jelly detritus were observed across the Oman margin transect. Associated chemosynthetic bacteria may have provided an organic-rich food source for foraminifera at these sites. Our data suggest that foraminifera in OMZ settings can utilise a variety of food sources and metabolic pathways to meet their energetic demands

The impact of deep-sea fisheries and implementation of the UNGA Resolutions 61/105 and 64/72. Report of an international scientific workshop

The scientific workshop to review fisheries management, held in Lisbon in May 2011, brought together 22 scientists and fisheries experts from around the world to consider the United Nations General Assembly (UNGA) resolutions on high seas bottom fisheries: what progress has been made and what the outstanding issues are. This report summarises the workshop conclusions, identifying examples of good practice and making recommendations in areas where it was agreed that the current management measures fall short of their target

Links between deep-sea respiration and community dynamics

It has been challenging to establish the mechanisms that link ecosystem functioning to environmental and resource variation, as well as community structure, composition and compensatory dynamics. A compelling hypothesis of compensatory dynamics, known as 'zero-sum' dynamics, is framed in terms of energy resource and demand units, where there is an inverse link between the number of individuals in a community and the mean individual metabolic rate. However, body-size energy distributions that are non-uniform suggest a niche advantage at a particular size class, which suggests a limit to which metabolism can explain community structuring. Since 1989, the composition and structure of abyssal seafloor communities in the northeast Pacific and northeast Atlantic have varied inter-annually with links to climate and resource variation. Here, for the first time, class and mass-specific individual respiration rates were examined along with resource supply and time series of density and biomass data of the dominant abyssal megafauna, echinoderms. Both sites had inverse relationships between density and mean individual metabolic rate. We found fourfold variation in echinoderm respiration over inter-annual timescales at both sites, which were linked to shifts in species composition and structure. In the north-eastern Pacific, the respiration of mobile surface deposit feeding echinoderms was positively linked to climate-driven particulate organic carbon fluxes with a temporal lag of about one year, respiring about 1-6% of the annual particulate organic carbon flux

The impact of deep-sea fisheries and implementation of the UNGA Resolutions 61/105 and 64/72. Report of an international scientific workshop, National Oceanography Centre, Southampton

The scientific workshop to review fisheries management, held in Lisbon in May 2011, brought together 22 scientists and fisheries experts from around the world to consider the United Nations General Assembly (UNGA) resolutions on high seas bottom fisheries: what progress has been made and what the outstanding issues are. This report summarises the workshop conclusions, identifying examples of good practice and making recommendations in areas where it was agreed that the current management measures fall short of their target.Peer reviewe

RRS Charles Darwin Cruise 179, 14 Apr - 17 May 2006. Hotspot ecosystem research in the Setúbal, Lisbon, Cascais and Nazaré canyons on the Portuguese continental margin

RRS Charles Darwin Cruise 179 was one of a series of cruises studying the biology, geology, biogeochemistry and physical oceanography of the Portuguese margin canyons. The cruise contributed to the European Union Framework Programme VI Integrated Project HERMES (Hotspot Ecosystem Research on the Margins of European Seas). Four key canyon areas on the European margin are being studied in HERMES: the Portuguese margin, the Irish margin and the Western and Eastern Mediterranean. On the Portuguese margin four canyons had been selected for multidisciplinary studies by the HERMES community: the Nazaré Canyon, Setúbal Canyon, Lisbon Canyon and the Cascais Canyon.RRS Charles Darwin cruise 179 was divided into two legs (Cartagena to Lisbon, 14 April to 1 May 2006; Lisbon to Falmouth, 1 to 17 May 2006). Leg 1 focused on the upper and middle parts of the Setúbal and Lisbon canyons, which join together at a depth of about 2000m, and the upper and middle Cascais Canyon. Leg 2 sampled the lower Cascais and Setúbal canyons and a wide variety of depths in the Nazaré Canyon. The principal sampling activities were seabed photographic and video imaging (NOCS SHRIMP system), deep-tow 30 kHz sidescan sonar imaging (NOCS TOBI system), coring (Megacorer, Piston Corer and Box Corer), trawling (Agassiz Trawl), and benthic boundary layer particulate biogeochemistry using CTD-mounted Stand Alone Pump Systems (SAPS).Seabed photo-transects at depths between 300 and 4500m confirmed that large parts of all the canyons were covered in a sediment drape, with little evidence of epifaunal megafauna within the canyon axis, but with localised communities of suspension feeding sponges, cnidarians (soft and stony corals), crinoids and asteroids on rocky ledges around the thalweg (central channel) of the canyons. Photo-transects across the thalwegs of the canyons revealed fascinating changes in the nature of the seabed (e.g. ripple patterns) and fauna (e.g. xenophyophores (giant protozoans) on the flanks of the Nazaré Canyon thalweg). New sidescan sonar images were obtained of the Lisbon and Cascais canyons and the base of the continental slope in the vicinity of the Cascais and Setúbal canyons. Coring and trawling focused on comparable sites at c. 3400m and 4400m in the lower canyons. Burrowing holothurians were evident in all three canyons at c. 3400m, but only in the Nazaré Canyon were they superabundant.This was the penultimate scientific cruise of RRS Charles Darwin. The ship has given UK and European marine science many years of excellent service. She will be greatly missed, and will be succeeded by RRS James Cook in 2006