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Changes in habitat-forming organisms can have complex consequences for associated species. Sessile epibenthic glass 'plate' sponges (Porifera: Hexactinellida) are conspicuous inhabitants of soft-sediment abyssal areas and their siliceous spicules create persistent spicule patches on the seafloor. Sponge spicule patch density, spatial dispersion, and percent cover were examined over a sevenyear period (2006-2013) using remotely operated vehicle videos from Station M in the abyssal northeast Pacific (50 00N, 123 00W, ~4,000 m depth). There was an apparent large increase in newly dead plate sponges in February 2007 compared with December 2006, with this trend continuing through June 2007 (mean 0.03 % cover increasing to 0.33 %). A second increase in mean percent cover of dead plate sponges occurred from May 2011 (0.24 %) through June 2012 (0.60 %). Among the 28 megafaunal taxa occurring in association with the patches, the distributions of three taxa [two sponge taxa (Porifera) and brittle stars (Ophiuroidea)] suggested selectivity for the sponge spicule patches. The community structure of visible megafauna within sponge spicule patches was different when compared with that outside the patches suggesting that the sponges, after death, provide preferred habitat patches for certain benthic megafauna. These findings indicate that sponge spicule patches contribute to habitat heterogeneity in space and time., Introduction Characterizing deep-sea systems has become more important under changing climate and rising exploitation of deep-sea resources (Glover and Smith 2003; Thiel 2003; Ramirez-Llodra et al. 2011). Fine sediments dominate [...]

Pelagic forms of the brown algae (Phaeophyceae) Sargassum spp. and their conspicuous rafts are defining characteristics of the Sargasso Sea in the western North Atlantic. Given rising temperatures and acidity in the surface ocean, we hypothesized that macrofauna associated with Sargassum in the Sargasso Sea have changed with respect to species composition, diversity, evenness, and sessile epibiota coverage since studies were conducted 40 years ago. Sargassum communities were sampled along a transect through the Sargasso Sea in 2011 and 2012 and compared to samples collected in the Sargasso Sea, Gulf Stream, and south of the subtropical convergence zone from 1966 to 1975. Mobile macrofauna communities exhibited changes in community structure and declines in diversity and evenness within a 6-month time period (August 2011-February 2012). Equivalent declines in diversity and evenness were recorded in the same region (Sargasso Sea, 25°-29°N) in 1972-1973. Recent community structures were unlike any documented historically, whether compared to sites of the same latitude range within the Sargasso Sea, or the broader historical dataset of sites ranging across the Sargasso Sea, Gulf Stream, and south of the subtropical convergence zone. Recent samples also recorded low coverage by sessile epibionts, both calcifying forms and hydroids. The diversity and species composition of macrofauna communities associated with Sargassum might be inherently unstable. While several biological and oceanographic factors might have contributed to these observations, including a decline in pH, increase in summer temperatures, and changes in the abundance and distribution of Sargassum seaweed in the area, it is not currently possible to attribute direct causal links., Introduction Pelagic forms of the brown algae (Phaeophyceae) Sargassum are a defining characteristic of the Sargasso Sea. Ranging from approximately 20°-40°N and 30°-75°W (Butler et al. 1983; Coston-Clements et al. [...]

Time-series particle flux and seasonal sediment community oxygen consumption (SCOC) were measured in Port Foster (160 m water depth), Deception Island, Antarctica, beginning in March 1999 and continuing through November 2000. Sediment traps were moored at 50 and 20 m above bottom and collected sedimenting material for contiguous periods of 10 to 18.3 days. Fluxes of material increased in mid-winter of 1999 and 2000 but were more notable in 1999. Fluxes were higher in the deeper sediment trap and there was an inverse relationship between mass flux and % organic carbon and particulate total nitrogen. A piston-operated grab respirometer was deployed at 160 m depth for 35–60 h in November 1999, and in February, May/June, and November 2000, to measure SCOC and recover the sediment for organic carbon, nitrogen and pigment composition. SCOC, as an estimate of sediment community carbon demand, exceeded the organic carbon flux to the seafloor (supply), and alternative sources of organic carbon input to the benthos are discussed. Highest SCOC occurred in the austral summer during a particle-flux sampling hiatus in the summer of 2000. Fluxes were positively correlated with local wind speed measured at a terrestrial station positioned on a hill overlooking Port Foster. There was also a positive correlation between the particulate matter fluxes and the ratio of chlorophyll a to phaeopigments, an indicator of the “freshness” of material entering the sediment trap at 20 mab. [Copyright &y& Elsevier]

An autonomous weather station (Terrestrial station) was developed and deployed at Deception Island, Antarctica, an active volcanic island, to monitor the daily weather conditions as part of a long time-series marine ecosystem study of the sunken caldera, Port Foster. The principal components of the Terrestrial station were a time-lapse digital camera, ultrasonic wind sensor, controller, wind turbine generators, and batteries. The Terrestrial station was installed on a ridge at 200 m altitude overlooking Port Foster and the surrounding terrain from 9 March 1999 until 20 November 2000. Ice cover on Port Foster began in late July 2000 and was intermittently visible through early November. Daily averaged wind speeds ranged from 0.2 m s−1 in October to 47.4 m s−1 in June, with the prevailing direction from the southwest and less frequently from the northeast. Daily averaged air temperatures fluctuated from a low of −12.6°C in August 2000 to 2.7°C in March 1999. Weather conditions measured at Deception Island were generally consistent with those concurrently measured in the region of the South Shetland Islands. Ice cover in Port Foster was less pronounced in 1999 and 2000 than reported in previous years, suggesting regional warming. [Copyright &y& Elsevier]

Examines the relationship between the utilization of organic carbon by the sediment community and the production and downward flux of particulate matter through the water column. Measurements of sediment community oxygen consumption; Profiles of sediment chemical parameters and bacterial count; Composition of sediment community.

Examines the ecology of under-ice fauna, including the logistic intractability of the environment and the distribution and behavior of the animals in Weddell Sea, Antarctica. Use of free-vehicle acoustic instruments to monitor the abundance, vertical distribution, and size distribution; Use of target strength to generate estimates of animal body lenght.

Provides information on a study on visible detrital aggregates formed between July and December at an abyssal station in the northeastern Pacific. Methods used; Results; Comparison of the results with the data available on chemical composition and respiration associated with detrital materials in other deep-sea area of the World Ocean.

Addresses a discrepancy between particulate organic carbon (POC) flux and sediment community oxygen consumption (SCOC) in the North Pacific. Comparison of long-time series measurements of POC flux into the benthic boundary layer and concurrent, seasonal measurements of SCOC; Details.

A description of the oceanographic instrumentation developed and deployed at Deception Island, Antarctica during the period 9 March 1999 to 20 November 2000 as part of the ERUPT program is presented. This instrumentation includes (1) an autonomous weather station (Terrestrial station) to record daily conditions and ice-cover, (2) an underwater time-lapse camera/sediment trap array to photograph the abundance and movements of bottom-dwelling animals and collect sinking particulate matter, (3) an acoustic array to monitor movements of macrozooplankton and nekton, (4) an autonomous, vertically profiling pump sampler to capture and preserve plankton and nekton from discrete depths, (5) thermistor arrays to record water temperature at various depths, (6) an acoustic Doppler profiler to record current velocities at discrete depths, and (7) a piston-operated grab respirometer to measure sediment community oxygen consumption and recover sediments. The Terrestrial station and thermistor arrays, current meter and grab respirometer were the most successful instruments deployed, producing large data sets. The acoustic array produced some data of limited value, while the camera tripod and pump sampler produced no useful data due to technical and operational problems. [Copyright &y& Elsevier]