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Paul Dando

The Marine Biological Association of the UK, None, Emeritus

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Paul has worked as a marine scientist for over 55 years, mainly at the Marine Biological Association of the UK (MBA), in Plymouth, but with a period of 13 years as Professor of Marine Biology at Bangor University. His research interests include; the environmental effects of hydrothermal vents, hydrocarbon seeps and submarine ground water seeps, including their roles in geochemical cycles and benthic production: the behaviour, biochemistry and physiology of bivalves and frenulate pogonophores with methanotrophic and/or chemoautotrophic bacterial symbionts and the distribution and home ranges of fish in estuaries, including their spawning and nursery grounds. His research areas have ranged from the Mediterranean to mid-Atlantic and the Arctic and in the NE Pacific from Panama to the Gulf of California and northwards to the Canadian coast, using research vessels from 10 countries. Paul has coordinated three international projects and has been editor-in-chief of the Journal of the Marine Biological Association of the UK.

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Julian D Reynolds

Trinity College Dublin

Kristen J Gremillion

Ohio State University

Iowa State University

Kansas State University

Armando Marques-Guedes

UNL - New University of Lisbon

José F. González-Maya

Universidad Autónoma Metropolitana-Lerma

University of New England - Australia

Universidade Federal de Santa Catarina - UFSC (Federal University of Santa Catarina)

Hemwati Nandan Bahuguna Garhwal University

taufik budhi pramono

Jenderal Soedirman University

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Papers by Paul Dando

Study of food chains at methane seeps in the North Sea

SIGLEAvailable from British Library Document Supply Centre-DSC:3614.6031(05) / BLDSC - British Li... more

The Chemical Biology of Fishes (Volume 2)

Biochemical Society Transactions, 1982

This is the book to consult if you wish to know the concentration of silver or of sialic acid in ... more

In Situ Investigations Of Shallow Water Hydrothermal Vent Systems, Palaeochori Bay, Milos, Aegean Sea

ABSTRACT Shallow hydrothermal vent systems in Palaeochori Bay, Milos, Aegean Sea were characteriz... more ABSTRACT Shallow hydrothermal vent systems in Palaeochori Bay, Milos, Aegean Sea were characterized in terms of their flow of fluid, gas, heat and chemicals The chemistry and fluid flow through the sediments around the vents and the activity of micro-organisms inhabiting the ambient seawater were studied using equipment accurately positioned by scientific divers. In situ measurements confirmed the shallow vent sites to be extreme environments of low pH and high temperature The outflow of gas or hot liquid through the permeable sediment induced a convection cell of pore-water entrainment from deeper in the sediment to the surface Nutrients and dissolved carbon dioxide were transported to the sediment surface across an area of 4m diameter around a single vent and ejected into the water column This outflow was compensated by an inflow of oxygen rich water over an area foaming a ring around the outflow region These geochemical conditions were reflected in the colour of the sediment and the type of precipitate or &#39;mat&#39; forming on the sediment surface. Gas and fluid flux measurements made at a number of vent sites indicate the mean flow of fluid discharge in Palaeochori Bay to be in the range 50 - 80 dm3 h -1. Despite the &#39;nutrient pump&#39; effect of the vent system, plankton biomass, photosynthesis and respiration remained low (&lt; 0 1 mg m-3,&lt; 1 mmol -3 -1 -3 -1 02 m d , 2-4 mmol 02 m d respectively) The water column was always dominated by respiring rather than photosynthesizing organisms No significant difference was found between plankton production at venting and non-venting sites despite a large range of ambient dissolved inorganic carbon concentration. By contrast, small changes in ambient temperature had a profound stimulatory effect on plankton respiration and a lesser effect on plankton photosynthesis.

Methane venting associated with submarine groundwater discharge in Eckernförde Bucht, Baltic sea

Abstract:Submarine groundwater discharges are responsible for pockmark depressions on the bed ofE... more Abstract:Submarine groundwater discharges are responsible for pockmark depressions on the bed ofEckernforde Bucht, Western Baltic. In these depressions there is an interface between almostfluid sediment and sea water that is typically about 1.5 2m below the surrounding seabed.Transects, made with a underwater digital video camera sled in October 1998 and September1999, showed that near the rims of the depressions the clay aquaclude was not covered byrecent methane generating organic sediment. Cracks could be seen in the clay indicating thatedges of the aquaclude layer are slowly collapsing into the steep sided depressions. Somesharply angular cobble sized clay clasts were seen just outside the pockmark rims suggestingthat blow-outs may occur. Acoustic turbidity is widespread in the sediments of the deeperparts of Eckernforde Bucht due to methane gas bubble formation within the sediment. Themethane seems to derive mainly from the decomposition of recent organic matter. Becausethe Buc...

Seismicity in the hellenic volcanic arc hydrothermal system in relation to geochemical parameters

Physics and Chemistry of the Earth, Part B: Hydrology, Oceans and Atmosphere, 2000

The aim of the paper is to study the microseismicity of the island of Milos, Greece, in order to ... more The aim of the paper is to study the microseismicity of the island of Milos, Greece, in order to relate the recorded earthquake signals to venting periodic@ and to understand better the role of episodic events. A seismic network of five three-component, triggering mode digital stations, installed on the island in the summer of 1996, recorded almost 400 local microearthquakes and 500 signals, tentatively associated with hydrothermal activity. The analysis indicates low seismic@, probably associated with the existing hydrothermal field of the area. The hydrothermal signals are of two types, with peak frequencies of 2-3 Hz and 20-30 Hz, respectively. Preliminary analysis of records from the same experiment in 1997 showed that a high concentration of seawater in particulates Mn was followed by a group of microearthquakes 6-8 hours later.

Biodiversity and Biogeography of Chthamalid Barnacles from the North-Eastern Pacific (Crustacea Cirripedia)

PLOS ONE, 2016

The biogeography and ecology of the species of Chthamalus present on the west coast of America ar... more

The history of the Journal of the Marine Biological Association of the United Kingdom and the influence of the publication on marine research

Journal of the Marine Biological Association of the United Kingdom

The origin and development of the Journal of the Marine Biological Association of the United King... more The origin and development of the Journal of the Marine Biological Association of the United Kingdom is described on the occasion of the publication of the 100th volume. Papers in the Journal demonstrate how the techniques and approaches to the study of the marine environment have evolved over the 120 years of publication. The early papers provided a baseline description of the marine environment and of marine communities that allowed the effects of later perturbations of the environment to be determined. Both the early papers and the long time series of records have proved to be particularly relevant as marine scientists try to predict the long-term results of climatic and anthropogenic effects on the marine ecosystem. The Journal has now become increasingly international, with most papers coming from outside Europe.

ObituaryAlan J. Southward (1928�2007)

Nature, 2008

Bathymetric characterization of tectonically active basins in the northern Gulf of California

The Wagner Basin can be considered a "nascent spreading centre" that evolved from a hal... more The Wagner Basin can be considered a "nascent spreading centre" that evolved from a half graben with a thick sediment cover that may mask magmatic activity at depth. The 200-210 m deep Wagner and Consag Basins are the northernmost of the 8 active extensional basins within the Gulf of California rift system and have been assumed to be mostly hydrothermally inactive; however, bathymetric data show dense deep faulting, mainly on the SE edge of the basins; additionally, the presence of extensive gas venting and heated sediments along the Wagner Fault was observed. Detailed bathymetry of the Wagner and Consag Basins shows the steep eastern edge of the basins bordered by the Wagner Fault. Bathymetry and profiler data revealed large vertical displacements due to faulting that disrupted the sedimentary column. More than 246 bubble plumes were mapped on the echo-sounder profiles, many rising to the surface from 65 -150 m depth and the area affected by low bottom pH, due to CO2 discharge, was in excess of 365 km2. Bubbles were observed breaking the sea surface from some large plumes. Only a minority of the vents present were mapped with the echo-sounders, since the closest survey lines were 1km apart. Based on the bottom coverage of the acoustic beam we estimate that there are at least 15,000 individual gas vents along the Wagner fault. Profiler images showed gas channels and chimneys associated with sedimentary layers. The gas plumes originated from sites of intense disruptions of the upper sediments (synsedimentary faults, pockmarks, mud domes and diapirs and raised irregular hard reflectors). Beneath the plumes, there were enhanced sedimentary reflectors and acoustic blanking indicative of subsurface gas accumulation. One of the strongest vents was associated with a mud diapir. Cemented sediments were common inside pockmarks and around gas outlets; 13 (22%) of grab and box core samples in the outgassing area contained these but in many cases the grab was empty after hitting a hard bottom. The nodules analyzed contained on average 83% of quartz and barite, and 12% of pyrite and gypsum. Calcite contributed only a small percentage of the total minerals found.

New information on the ecology of deep-sea vent communities in the azores triple junction area : preliminery results of the Diva 2 cruise (May 31-July 4, 1994)

Interridge News, 1994

Preliminary observations on biological communities at shallow hydrothermal vents in the Aegean Sea

Geological Society London Special Publications, 1995

... 1990) and off the coast of Kos and Yali (Varnavas & Cronan 1991). Venting of gas bubbles,... more

Long-Term Oceanographic and Ecological Research in the Western English Channel

Advances in Marine Biology, 2004

Spermatogenesis of Bathymodiolus azoricus in captivity matching reproductive behaviour at deep-sea hydrothermal vents

Journal of Experimental Marine Biology and Ecology, 2006

This study aims to improve our knowledge on the reproduction cycles of invertebrates from deep-se... more

Gas seep induced interstitial water circulation: observations and environmental implications

Continental Shelf Research, 1995

Ah&act-An interstitial water circulation, generated by gas flow through a permeable sediment, was... more Ah&act-An interstitial water circulation, generated by gas flow through a permeable sediment, was observed at an intertidal site on the Kattegat coast of Denmark. Concentrations of methane dissolved in the interstitial water of the near-surface sediment decreased sharply only centimetres away from gas seeps venting almost pure methane (-99% methane). Water was driven out of the sediment by the rising bubbles of gas at the seep and was replaced by an equivalent draw-down of overlying, oxygenated water into the surrounding sediment. This process steepened the chemical gradients close to the gas flow channel, with the effects progressively diminishing with increasing distance from the seep. The position of the redox potential discontinuity (RPD) moved by as much as 7 cm deeper into the sediment close to the seep: this effect was less marked, but still detectable, 50 cm away. The degree of displacement from the "normal" sediment profiles depended on the magnitude of the interstitial flow rate. The distribution of pore water pH and sulphate: sodium ratios were also dependent on the flow rate of the circulating water. The concentrations of sulphide, thiosulphate and sulphite in the interstitial water from the top 10 cm of sediment, were high at a seep, decreased to a minimum at 20-30 cm distance, then increased again at 40-50 cm distance. Laboratory experiments confirmed that gas bubbling through a fluid filled permeable matrix generated a flow, out of the sediment at the gas exit and into the sediment over the peripheral surfaces surrounding the outlet. Experimentally determined rates of dispersion, for gas flow rates of 3-20 ml min-', for a 40 g 1-l sodium chloride solution, were 62.5 x 1r9 to 540 x W9 m* s-l, 4o-400 times the molecular diffusion coefficient. Linear interstitial fluid velocities of 3-12 mm mitt-', were recorded at 14-3 cm from the seep axis respectively, with a gas flow rate of 5 ml min-'. Two-dimensional modelhng of the experimental system confirmed the flow pattern determined visually with dye. Implications of this process with regard to the recycling rates of elements generally, and of nutrient and waste materials, in particular, are discussed.

Gas venting rates from submarine hydrothermal areas around the island of Milos, Hellenic Volcanic Arc

Continental Shelf Research, 1995

Gas seeps were located, by echo sounding, SCUBA divers and ROV observations, at hydrothermal site... more Gas seeps were located, by echo sounding, SCUBA divers and ROV observations, at hydrothermal sites around the island of Milos, in the Hellenic Volcanic Arc. Samples were collected by SCUBA divers and by a ROV from water depths between 3 and 110 m. Fifty-six flow rates from 39 individual seeps were measured and these ranged from 0.2 to 18.5 1 h-' at the depth of collection. The major component, 54.9-91.9% of the gas, was carbon dioxide. Hydrogen (~3%), methane (59.7%) and hydrogen sulphide (58.1%) were also measured. Hydrothermal free gas fluxes from the submarine hydrothermal areas around Milos were estimated to be greater than lOto moles y-l. It was concluded that submarine gas seeps along volcanic island arcs may be an important carbon dioxide source.

Retrievable cages open up new era in deep-sea vent research

To date, regulation of activities (including scientific research), in and around hydrothermal ven... more

Bathymetric characterization of tectonically active basins in the northern Gulf of California

The Wagner Basin can be considered a "nascent spreading centre" that evolved from a hal... more The Wagner Basin can be considered a "nascent spreading centre" that evolved from a half graben with a thick sediment cover that may mask magmatic activity at depth. The 200-210 m deep Wagner and Consag Basins are the northernmost of the 8 active extensional basins within the Gulf of California rift system and have been assumed to be mostly hydrothermally inactive; however, bathymetric data show dense deep faulting, mainly on the SE edge of the basins; additionally, the presence of extensive gas venting and heated sediments along the Wagner Fault was observed. Detailed bathymetry of the Wagner and Consag Basins shows the steep eastern edge of the basins bordered by the Wagner Fault. Bathymetry and profiler data revealed large vertical displacements due to faulting that disrupted the sedimentary column. More than 246 bubble plumes were mapped on the echo-sounder profiles, many rising to the surface from 65 -150 m depth and the area affected by low bottom pH, due to CO2 discharge, was in excess of 365 km2. Bubbles were observed breaking the sea surface from some large plumes. Only a minority of the vents present were mapped with the echo-sounders, since the closest survey lines were 1km apart. Based on the bottom coverage of the acoustic beam we estimate that there are at least 15,000 individual gas vents along the Wagner fault. Profiler images showed gas channels and chimneys associated with sedimentary layers. The gas plumes originated from sites of intense disruptions of the upper sediments (synsedimentary faults, pockmarks, mud domes and diapirs and raised irregular hard reflectors). Beneath the plumes, there were enhanced sedimentary reflectors and acoustic blanking indicative of subsurface gas accumulation. One of the strongest vents was associated with a mud diapir. Cemented sediments were common inside pockmarks and around gas outlets; 13 (22%) of grab and box core samples in the outgassing area contained these but in many cases the grab was empty after hitting a hard bottom. The nodules analyzed contained on average 83% of quartz and barite, and 12% of pyrite and gypsum. Calcite contributed only a small percentage of the total minerals found.

Long-Term Oceanographic and Ecological Research in the Western English Channel

Advances in Marine Biology, 2004

Interactions between sediment chemistry and frenulate pogonophores (Annelida) in the north-east Atlantic

by P. Lamont and Paul Dando

Deep Sea Research Part I: Oceanographic Research Papers, 2008

The small frenulate pogonophores (Annelida: Pogonophora a.k.a. Siboglinidae) typically inhabit mu... more The small frenulate pogonophores (Annelida: Pogonophora a.k.a. Siboglinidae) typically inhabit muddy sediments on the continental slope, although a few species occur near hydrothermal vents and cold seeps. We present data on the distribution and habitat characteristics of several species on the European continental shelf and slope from 481N to 751N and show how the animals interact with the chemistry of the sediments. The environments inhabited include: shallow (30 m), organic-rich, fjord sediments; slope sediments (1000-2200 m) and methane seeps at 330 m depth. All the species studied obtain nutrition from endosymbiotic bacteria. They take up reduced sulphur species, or in one case, methane, through the posterior parts of their tubes buried in the anoxic sediment. We conclude that most species undertake sulphide 'mining', a mechanism previously demonstrated in the bivalves Lucinoma borealis and Thyasira sarsi. These pogonophores participate in the sulphur cycle and effectively lower the sulphide content of the sediments. Our results show that the abundance of frenulate pogonophores increases with increasing sedimentation and with decreasing abundance of other benthos, particularly bioturbating organisms. The maximum sustainable carrying capacity of non-seep sediments for frenulate pogonophores is limited by the rate of sulphate reduction.

In Situ Investigations Of Shallow Water Hydrothermal Vent Systems, Palaeochori Bay, Milos, Aegean Sea

by P. Linke and Paul Dando

Shallow hydrothermal vent systems in Palaeochori Bay, Milos, Aegean Sea were characterised in ter... more Shallow hydrothermal vent systems in Palaeochori Bay, Milos, Aegean Sea were characterised in terms of their flow of fluid, gas, heat and chemicals. The chemistry and fluid flow through the sediments around the vents and the activity of micro-organisms inhabiting the ambient seawater were studied using equipment accurately positioned by scientific divers.

Study of food chains at methane seeps in the North Sea

SIGLEAvailable from British Library Document Supply Centre-DSC:3614.6031(05) / BLDSC - British Li... more

The Chemical Biology of Fishes (Volume 2)

Biochemical Society Transactions, 1982

This is the book to consult if you wish to know the concentration of silver or of sialic acid in ... more

In Situ Investigations Of Shallow Water Hydrothermal Vent Systems, Palaeochori Bay, Milos, Aegean Sea

ABSTRACT Shallow hydrothermal vent systems in Palaeochori Bay, Milos, Aegean Sea were characteriz... more ABSTRACT Shallow hydrothermal vent systems in Palaeochori Bay, Milos, Aegean Sea were characterized in terms of their flow of fluid, gas, heat and chemicals The chemistry and fluid flow through the sediments around the vents and the activity of micro-organisms inhabiting the ambient seawater were studied using equipment accurately positioned by scientific divers. In situ measurements confirmed the shallow vent sites to be extreme environments of low pH and high temperature The outflow of gas or hot liquid through the permeable sediment induced a convection cell of pore-water entrainment from deeper in the sediment to the surface Nutrients and dissolved carbon dioxide were transported to the sediment surface across an area of 4m diameter around a single vent and ejected into the water column This outflow was compensated by an inflow of oxygen rich water over an area foaming a ring around the outflow region These geochemical conditions were reflected in the colour of the sediment and the type of precipitate or &#39;mat&#39; forming on the sediment surface. Gas and fluid flux measurements made at a number of vent sites indicate the mean flow of fluid discharge in Palaeochori Bay to be in the range 50 - 80 dm3 h -1. Despite the &#39;nutrient pump&#39; effect of the vent system, plankton biomass, photosynthesis and respiration remained low (&lt; 0 1 mg m-3,&lt; 1 mmol -3 -1 -3 -1 02 m d , 2-4 mmol 02 m d respectively) The water column was always dominated by respiring rather than photosynthesizing organisms No significant difference was found between plankton production at venting and non-venting sites despite a large range of ambient dissolved inorganic carbon concentration. By contrast, small changes in ambient temperature had a profound stimulatory effect on plankton respiration and a lesser effect on plankton photosynthesis.

Methane venting associated with submarine groundwater discharge in Eckernförde Bucht, Baltic sea

Abstract:Submarine groundwater discharges are responsible for pockmark depressions on the bed ofE... more Abstract:Submarine groundwater discharges are responsible for pockmark depressions on the bed ofEckernforde Bucht, Western Baltic. In these depressions there is an interface between almostfluid sediment and sea water that is typically about 1.5 2m below the surrounding seabed.Transects, made with a underwater digital video camera sled in October 1998 and September1999, showed that near the rims of the depressions the clay aquaclude was not covered byrecent methane generating organic sediment. Cracks could be seen in the clay indicating thatedges of the aquaclude layer are slowly collapsing into the steep sided depressions. Somesharply angular cobble sized clay clasts were seen just outside the pockmark rims suggestingthat blow-outs may occur. Acoustic turbidity is widespread in the sediments of the deeperparts of Eckernforde Bucht due to methane gas bubble formation within the sediment. Themethane seems to derive mainly from the decomposition of recent organic matter. Becausethe Buc...

Seismicity in the hellenic volcanic arc hydrothermal system in relation to geochemical parameters

Physics and Chemistry of the Earth, Part B: Hydrology, Oceans and Atmosphere, 2000

The aim of the paper is to study the microseismicity of the island of Milos, Greece, in order to ... more The aim of the paper is to study the microseismicity of the island of Milos, Greece, in order to relate the recorded earthquake signals to venting periodic@ and to understand better the role of episodic events. A seismic network of five three-component, triggering mode digital stations, installed on the island in the summer of 1996, recorded almost 400 local microearthquakes and 500 signals, tentatively associated with hydrothermal activity. The analysis indicates low seismic@, probably associated with the existing hydrothermal field of the area. The hydrothermal signals are of two types, with peak frequencies of 2-3 Hz and 20-30 Hz, respectively. Preliminary analysis of records from the same experiment in 1997 showed that a high concentration of seawater in particulates Mn was followed by a group of microearthquakes 6-8 hours later.

Biodiversity and Biogeography of Chthamalid Barnacles from the North-Eastern Pacific (Crustacea Cirripedia)

PLOS ONE, 2016

The biogeography and ecology of the species of Chthamalus present on the west coast of America ar... more

The history of the Journal of the Marine Biological Association of the United Kingdom and the influence of the publication on marine research

Journal of the Marine Biological Association of the United Kingdom

The origin and development of the Journal of the Marine Biological Association of the United King... more The origin and development of the Journal of the Marine Biological Association of the United Kingdom is described on the occasion of the publication of the 100th volume. Papers in the Journal demonstrate how the techniques and approaches to the study of the marine environment have evolved over the 120 years of publication. The early papers provided a baseline description of the marine environment and of marine communities that allowed the effects of later perturbations of the environment to be determined. Both the early papers and the long time series of records have proved to be particularly relevant as marine scientists try to predict the long-term results of climatic and anthropogenic effects on the marine ecosystem. The Journal has now become increasingly international, with most papers coming from outside Europe.

ObituaryAlan J. Southward (1928�2007)

Nature, 2008

Bathymetric characterization of tectonically active basins in the northern Gulf of California

The Wagner Basin can be considered a "nascent spreading centre" that evolved from a hal... more The Wagner Basin can be considered a "nascent spreading centre" that evolved from a half graben with a thick sediment cover that may mask magmatic activity at depth. The 200-210 m deep Wagner and Consag Basins are the northernmost of the 8 active extensional basins within the Gulf of California rift system and have been assumed to be mostly hydrothermally inactive; however, bathymetric data show dense deep faulting, mainly on the SE edge of the basins; additionally, the presence of extensive gas venting and heated sediments along the Wagner Fault was observed. Detailed bathymetry of the Wagner and Consag Basins shows the steep eastern edge of the basins bordered by the Wagner Fault. Bathymetry and profiler data revealed large vertical displacements due to faulting that disrupted the sedimentary column. More than 246 bubble plumes were mapped on the echo-sounder profiles, many rising to the surface from 65 -150 m depth and the area affected by low bottom pH, due to CO2 discharge, was in excess of 365 km2. Bubbles were observed breaking the sea surface from some large plumes. Only a minority of the vents present were mapped with the echo-sounders, since the closest survey lines were 1km apart. Based on the bottom coverage of the acoustic beam we estimate that there are at least 15,000 individual gas vents along the Wagner fault. Profiler images showed gas channels and chimneys associated with sedimentary layers. The gas plumes originated from sites of intense disruptions of the upper sediments (synsedimentary faults, pockmarks, mud domes and diapirs and raised irregular hard reflectors). Beneath the plumes, there were enhanced sedimentary reflectors and acoustic blanking indicative of subsurface gas accumulation. One of the strongest vents was associated with a mud diapir. Cemented sediments were common inside pockmarks and around gas outlets; 13 (22%) of grab and box core samples in the outgassing area contained these but in many cases the grab was empty after hitting a hard bottom. The nodules analyzed contained on average 83% of quartz and barite, and 12% of pyrite and gypsum. Calcite contributed only a small percentage of the total minerals found.

New information on the ecology of deep-sea vent communities in the azores triple junction area : preliminery results of the Diva 2 cruise (May 31-July 4, 1994)

Interridge News, 1994

Preliminary observations on biological communities at shallow hydrothermal vents in the Aegean Sea

Geological Society London Special Publications, 1995

... 1990) and off the coast of Kos and Yali (Varnavas & Cronan 1991). Venting of gas bubbles,... more

Long-Term Oceanographic and Ecological Research in the Western English Channel

Advances in Marine Biology, 2004

Spermatogenesis of Bathymodiolus azoricus in captivity matching reproductive behaviour at deep-sea hydrothermal vents

Journal of Experimental Marine Biology and Ecology, 2006

This study aims to improve our knowledge on the reproduction cycles of invertebrates from deep-se... more

Gas seep induced interstitial water circulation: observations and environmental implications

Continental Shelf Research, 1995

Ah&act-An interstitial water circulation, generated by gas flow through a permeable sediment, was... more Ah&act-An interstitial water circulation, generated by gas flow through a permeable sediment, was observed at an intertidal site on the Kattegat coast of Denmark. Concentrations of methane dissolved in the interstitial water of the near-surface sediment decreased sharply only centimetres away from gas seeps venting almost pure methane (-99% methane). Water was driven out of the sediment by the rising bubbles of gas at the seep and was replaced by an equivalent draw-down of overlying, oxygenated water into the surrounding sediment. This process steepened the chemical gradients close to the gas flow channel, with the effects progressively diminishing with increasing distance from the seep. The position of the redox potential discontinuity (RPD) moved by as much as 7 cm deeper into the sediment close to the seep: this effect was less marked, but still detectable, 50 cm away. The degree of displacement from the "normal" sediment profiles depended on the magnitude of the interstitial flow rate. The distribution of pore water pH and sulphate: sodium ratios were also dependent on the flow rate of the circulating water. The concentrations of sulphide, thiosulphate and sulphite in the interstitial water from the top 10 cm of sediment, were high at a seep, decreased to a minimum at 20-30 cm distance, then increased again at 40-50 cm distance. Laboratory experiments confirmed that gas bubbling through a fluid filled permeable matrix generated a flow, out of the sediment at the gas exit and into the sediment over the peripheral surfaces surrounding the outlet. Experimentally determined rates of dispersion, for gas flow rates of 3-20 ml min-', for a 40 g 1-l sodium chloride solution, were 62.5 x 1r9 to 540 x W9 m* s-l, 4o-400 times the molecular diffusion coefficient. Linear interstitial fluid velocities of 3-12 mm mitt-', were recorded at 14-3 cm from the seep axis respectively, with a gas flow rate of 5 ml min-'. Two-dimensional modelhng of the experimental system confirmed the flow pattern determined visually with dye. Implications of this process with regard to the recycling rates of elements generally, and of nutrient and waste materials, in particular, are discussed.

Gas venting rates from submarine hydrothermal areas around the island of Milos, Hellenic Volcanic Arc

Continental Shelf Research, 1995

Gas seeps were located, by echo sounding, SCUBA divers and ROV observations, at hydrothermal site... more Gas seeps were located, by echo sounding, SCUBA divers and ROV observations, at hydrothermal sites around the island of Milos, in the Hellenic Volcanic Arc. Samples were collected by SCUBA divers and by a ROV from water depths between 3 and 110 m. Fifty-six flow rates from 39 individual seeps were measured and these ranged from 0.2 to 18.5 1 h-' at the depth of collection. The major component, 54.9-91.9% of the gas, was carbon dioxide. Hydrogen (~3%), methane (59.7%) and hydrogen sulphide (58.1%) were also measured. Hydrothermal free gas fluxes from the submarine hydrothermal areas around Milos were estimated to be greater than lOto moles y-l. It was concluded that submarine gas seeps along volcanic island arcs may be an important carbon dioxide source.

Retrievable cages open up new era in deep-sea vent research

To date, regulation of activities (including scientific research), in and around hydrothermal ven... more

Bathymetric characterization of tectonically active basins in the northern Gulf of California

The Wagner Basin can be considered a "nascent spreading centre" that evolved from a hal... more The Wagner Basin can be considered a "nascent spreading centre" that evolved from a half graben with a thick sediment cover that may mask magmatic activity at depth. The 200-210 m deep Wagner and Consag Basins are the northernmost of the 8 active extensional basins within the Gulf of California rift system and have been assumed to be mostly hydrothermally inactive; however, bathymetric data show dense deep faulting, mainly on the SE edge of the basins; additionally, the presence of extensive gas venting and heated sediments along the Wagner Fault was observed. Detailed bathymetry of the Wagner and Consag Basins shows the steep eastern edge of the basins bordered by the Wagner Fault. Bathymetry and profiler data revealed large vertical displacements due to faulting that disrupted the sedimentary column. More than 246 bubble plumes were mapped on the echo-sounder profiles, many rising to the surface from 65 -150 m depth and the area affected by low bottom pH, due to CO2 discharge, was in excess of 365 km2. Bubbles were observed breaking the sea surface from some large plumes. Only a minority of the vents present were mapped with the echo-sounders, since the closest survey lines were 1km apart. Based on the bottom coverage of the acoustic beam we estimate that there are at least 15,000 individual gas vents along the Wagner fault. Profiler images showed gas channels and chimneys associated with sedimentary layers. The gas plumes originated from sites of intense disruptions of the upper sediments (synsedimentary faults, pockmarks, mud domes and diapirs and raised irregular hard reflectors). Beneath the plumes, there were enhanced sedimentary reflectors and acoustic blanking indicative of subsurface gas accumulation. One of the strongest vents was associated with a mud diapir. Cemented sediments were common inside pockmarks and around gas outlets; 13 (22%) of grab and box core samples in the outgassing area contained these but in many cases the grab was empty after hitting a hard bottom. The nodules analyzed contained on average 83% of quartz and barite, and 12% of pyrite and gypsum. Calcite contributed only a small percentage of the total minerals found.

Long-Term Oceanographic and Ecological Research in the Western English Channel

Advances in Marine Biology, 2004

Interactions between sediment chemistry and frenulate pogonophores (Annelida) in the north-east Atlantic

by P. Lamont and Paul Dando

Deep Sea Research Part I: Oceanographic Research Papers, 2008

The small frenulate pogonophores (Annelida: Pogonophora a.k.a. Siboglinidae) typically inhabit mu... more The small frenulate pogonophores (Annelida: Pogonophora a.k.a. Siboglinidae) typically inhabit muddy sediments on the continental slope, although a few species occur near hydrothermal vents and cold seeps. We present data on the distribution and habitat characteristics of several species on the European continental shelf and slope from 481N to 751N and show how the animals interact with the chemistry of the sediments. The environments inhabited include: shallow (30 m), organic-rich, fjord sediments; slope sediments (1000-2200 m) and methane seeps at 330 m depth. All the species studied obtain nutrition from endosymbiotic bacteria. They take up reduced sulphur species, or in one case, methane, through the posterior parts of their tubes buried in the anoxic sediment. We conclude that most species undertake sulphide 'mining', a mechanism previously demonstrated in the bivalves Lucinoma borealis and Thyasira sarsi. These pogonophores participate in the sulphur cycle and effectively lower the sulphide content of the sediments. Our results show that the abundance of frenulate pogonophores increases with increasing sedimentation and with decreasing abundance of other benthos, particularly bioturbating organisms. The maximum sustainable carrying capacity of non-seep sediments for frenulate pogonophores is limited by the rate of sulphate reduction.

In Situ Investigations Of Shallow Water Hydrothermal Vent Systems, Palaeochori Bay, Milos, Aegean Sea

by P. Linke and Paul Dando

Shallow hydrothermal vent systems in Palaeochori Bay, Milos, Aegean Sea were characterised in ter... more Shallow hydrothermal vent systems in Palaeochori Bay, Milos, Aegean Sea were characterised in terms of their flow of fluid, gas, heat and chemicals. The chemistry and fluid flow through the sediments around the vents and the activity of micro-organisms inhabiting the ambient seawater were studied using equipment accurately positioned by scientific divers.