ALBERT

Description: Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution May 1989

Description: Deep-sea benthic communities dependent on chemosynthetic primary production are associated with areas of active venting of chemically-modified seawater. Patterns in the distribution of species that occur at hydrothermal vents can be used to predict locations of the vent sites. Patterns in the distributions of species among vents along ridge segments are used to identify the spatial scales over which biological and physical processes operate to control community composition. Within a vent, a zonation in species distributions correlates with gradients of temperature and water chemistry. Along a given ridge segment, vent communities share the same species pool, but the relative abundance of each species varies from one site to another. On a basin-wide scale, the fauna of vent communities represent biological continua, where gradual morphological and genetic differentiation in species is correlated with increasing distance between vent sites. Differentiation of distinctive faunals assemblages at vents occursat a global scale. Populations of species at vents are established and maintained through recruitment of larval stages. To study recruitment processes at vent sites, slate panels were placed at and near vent sites on the seafloor for varying lengths of time. Size distributions of animals on retrieved panels suggest that recruitment is an intermittent or continuous process rather than a single episodic event. Recruitment of vent-associated species was greater on panels placed within vent communities compared to panels placed adjacent to these communities, a pattern consistent with the observed maintenance of communities in discrete regions of hydrothermal flux. The trophic structure of chemosynthetic communities can be complex. Primary production by chemoautotrophic bacteria can take place within host tissues of some invertebrates as well as on surfaces and in the water column and subsurface conduits. Carbon and nitrogen isotopic compositions of host tissues can be used to demonstrate the dependence of symbiont species on chemosynthetically-derived organic material. From the patterns in the isotopic compositions of vent and seep symbionts, potential sources of inorganic carbon are identified. Deep-water dissolved inorganic carbon serves as a large, isotopically buffered pool of inorganic carbon used by tubeworms and bivalves at hydrothermal communities of Juan de Fuca, Gorda, Guaymas Basin, East Pacific Rise, Galapagos, and Marianas vents. Variability in tubeworm carbon isotopic compositions at seeps may be attributed to significant contributions of isotopically variable DIC in seep effluents. Isotopic techniques are also used to explore trophic relationships among a variety of heterotrophic and symbiont-containing fauna at Hanging Gardens on the East Pacific Rise and at Marianas vents. Carbon isotopic measurements suggest that free-living bacteria are important sources of food at both sites. Nitrogen isotopic analyses show that the Marianas community may be simpler in trophic structure than the Hanging Gardens community. The biomass of most known vent sites is conspicuously dominated by large invertebrates with symbiotic bacteria. At vent sites on the Mid-Atlantic Ridge, large swarms of shrimp dominate the biomass. There is no evidence for endosymbionts in these shrimp, based on analyses of morphology, stable isotopes, lipopolysaccharides and ribulose- l, 5-bisphosphate carboxylase activity. Instead, the shrimp appear to be normal heterotrophs, grazing on free-living microorganisms associated with black smoker chimneys. High bacterial productivity within the sulfide matrix of the chimneys must be required to sustain the shrimp populations. Hydrothermal vent environments exhibit some of the most extreme gradients of temperature and chemistry found in the biosphere. Many of the animals that colonize vent sites exhibit adaptations that allow them to exist in such an unusual environment. A novel eye in shrimp from Mid-Atlantic Ridge vents is described. The eye, comprised of a pair of large organs within the cephalothorax, contains a visual pigment but lacks image-forming optics. The eye appears to be adapted for detection of low-level illumination and is suggested to have evolved in response to a source of radiation associated with the environment of hydrothermal vents. An electronic camera was used to detect light emitted from high-temperature (350°C) plumes that rise from the orifice of black smoker chimneys on the Endeavour Segment of the Juan de Fuca Ridge. Calculations suggest that thermal radiation from hot water may account for most of the light detected and that this light may be sufficient for geothermally-drive photosynthesis by bacteria.

Description: Portions of this dissertation were supported by grants from NSF, ONR, Sea Grant, and the WHOI Ocean Ventures Fund, by the WHOI Education Office, the WHOI Biology Department, and an NSF graduate fellowship.

Description: © Macmillan Publishers Limited, 2012. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Nature Communications 3 (2012): 620, doi:10.1038/ncomms1636.

Description: The Mid-Cayman spreading centre is an ultraslow-spreading ridge in the Caribbean Sea. Its extreme depth and geographic isolation from other mid-ocean ridges offer insights into the effects of pressure on hydrothermal venting, and the biogeography of vent fauna. Here we report the discovery of two hydrothermal vent fields on the Mid-Cayman spreading centre. The Von Damm Vent Field is located on the upper slopes of an oceanic core complex at a depth of 2,300 m. High-temperature venting in this off-axis setting suggests that the global incidence of vent fields may be underestimated. At a depth of 4,960 m on the Mid-Cayman spreading centre axis, the Beebe Vent Field emits copper-enriched fluids and a buoyant plume that rises 1,100 m, consistent with 〉 400 °C venting from the world’s deepest known hydrothermal system. At both sites, a new morphospecies of alvinocaridid shrimp dominates faunal assemblages, which exhibit similarities to those of Mid-Atlantic vents.

Description: This work is supported by a UK NERC award (NE/F017774/1 & NE/F017758/1) to J.T.C., D.P.C., B.J.M., K.S. and P.A.T., Royal Society Travel Grant 2009/R3 to R.C.S., A.M. is supported by SENSEnet, a Marie Curie Initial Training Network (ITN) funded by the European Commission Seventh Framework Programme, Contract Number PITN-GA-2009-237868 and a NASA ASTEP Grant NNX09AB75G to C.R.G. and C.L.V.D., which are gratefully acknowledged.

Description: © The Author(s), 2016. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 137 (2017): 297–306, doi:10.1016/j.dsr2.2016.05.007.

Description: The current standard for large-volume (thousands of cubic meters) zooplankton sampling in the deep sea is the MOCNESS, a system of multiple opening–closing nets, typically lowered to within 50 m of the seabed and towed obliquely to the surface to obtain low-spatial-resolution samples that integrate across 10 s of meters of water depth. The SyPRID (Sentry Precision Robotic Impeller Driven) sampler is an innovative, deep-rated (6000 m) plankton sampler that partners with the Sentry Autonomous Underwater Vehicle (AUV) to obtain paired, large-volume plankton samples at specified depths and survey lines to within 1.5 m of the seabed and with simultaneous collection of sensor data. SyPRID uses a perforated Ultra-High-Molecular-Weight (UHMW) plastic tube to support a fine mesh net within an outer carbon composite tube (tube-within-a-tube design), with an axial flow pump located aft of the capture filter. The pump facilitates flow through the system and reduces or possibly eliminates the bow wave at the mouth opening. The cod end, a hollow truncated cone, is also made of UHMW plastic and includes a collection volume designed to provide an area where zooplankton can collect, out of the high flow region. SyPRID attaches as a saddle-pack to the Sentry vehicle. Sentry itself is configured with a flight control system that enables autonomous survey paths to low altitudes. In its verification deployment at the Blake Ridge Seep (2160 m) on the US Atlantic Margin, SyPRID was operated for 6 h at an altitude of 5 m. It recovered plankton samples, including delicate living larvae, from the near-bottom stratum that is seldom sampled by a typical MOCNESS tow. The prototype SyPRID and its next generations will enable studies of plankton or other particulate distributions associated with localized physico-chemical strata in the water column or above patchy habitats on the seafloor.

Description: This work is part of the SeepC Project funded by the National Science Foundation through OCE-1031050 (Van Dover) and 1030453 (Young), together with funds for development of SyPRID and Sentry operations (OCE-1036843; A Bowen, WHOI).

Description: Author Posting. © The Authors, 2010. This is the author's version of the work. It is posted here by permission of National Academy of Sciences for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of America 107 (2010): 14020-14025, doi:10.1073/pnas.1009205107.

Description: Thirty years after the first discovery of high-temperature submarine venting, the vast majority of the global Mid Ocean Ridge remains unexplored for hydrothermal activity. Of particular interest are the world’s ultra-slow spreading ridges which were the last to be demonstrated to host high-temperature venting, but may host systems particularly relevant to pre-biotic chemistry and the origins of life. Here we report first evidence for diverse and very deep hydrothermal vents along the ~110 km long, ultra-slow spreading Mid-Cayman Rise. Our data indicate that the Mid- Cayman Rise hosts at least three discrete hydrothermal sites, each representing a different type of water-rock interaction, including both mafic and ultra-mafic systems and, at ~5000 m, the deepest known hydrothermal vent. Although submarine hydrothermal circulation, in which seawater percolates through and reacts with host lithologies, occurs on all mid-ocean ridges, the diversity of vent-types identified here and their relative geographic isolation make the Mid-Cayman Rise unique in the oceans. These new sites offer prospects for: an expanded range of vent-fluid compositions; varieties of abiotic organic chemical synthesis and extremophile microorganisms; and unparalleled faunal biodiversity - all in close proximity.

Description: This research was funded through NASA (ASTEP) and WHOI (Ocean Ridge Initiative).

Description: © The Author(s), 2022. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Woods, D., Cheadle, M., John, B., German, C., & Van Dover, C. Making use of relicts: brisingid seastars aggregate on hydrothermally inactive sulfide chimneys near black smokers. Frontiers in Marine Science, 9, (2022): 774628, https://doi.org/10.3389/fmars.2022.774628.

Description: When hydrothermal activity ceases at black-smoker chimneys on mid-ocean ridges, populations of associated invertebrates hosting chemoautotrophic endosymbionts decline and then disappear, but the chimneys can persist on the seabed as relicts. Suspension-feeding brisingid seastars colonize hydrothermally inactive (relict) chimneys on the East Pacific Rise (EPR), though their distribution relative to available hard substrata and proximity to hydrothermal activity is poorly documented. In this study, brisingid abundance on sulfide and basalt substrata was assessed along an ∼3,700 m ROV Jason II transect at the summit of Pito Seamount (SE Pacific; ∼2,275 m). Brisingids were non-randomly distributed, with highest densities (up to ∼300 m–2) on relict sulfides chimneys near active black smokers. Brisingids were relatively uncommon on basalt substrata, and absent on black smokers. We infer that both relict sulfide structures and proximity to black smokers play key roles in the maintenance of dense brisingid populations on Pito Seamount and in similar environments on the EPR. Our observations suggest that experimental introduction of “artificial” relict chimneys providing microtopographic relief could test whether such an approach might mitigate potential impacts of mineral extraction on populations of suspension-feeding invertebrates.

Description: his project was partially supported by the Global Ocean Biodiversity Initiative through the International Climate Initiative (IKI; grant no. 16_IV_049_Global_A_Global Ocean Biodiversity Initiative GOBI). The Federal Ministry for the Environment, Nature Conservation, and Nuclear Safety (BMU) supports IKI on the basis of a decision adopted by the German Bundestag. DW was supported by Duke University funds to CV. CG’s participation was funded through WHOI’s Deep Ocean Exploration Institute. The AT37-08 cruise was funded by NSF OCE-1459462 (MC and BJ) and OCE-1459387 (J Gee, Scripps Institution of Oceanography).