Mullineaux Lauren S.

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Photographic identification guide to larvae at hydrothermal vents

(Woods Hole Oceanographic Institution, 2009-06) Mills, Susan W. ; Beaulieu, Stace E. ; Mullineaux, Lauren S.

The purpose of this guide is to assist researchers in the identification of larvae of benthic invertebrates at hydrothermal vents. Our work is based on plankton sampling at the East Pacific Rise 9-10°N vent field from 1991-2007, supplemented by benthic collections of juveniles. In addition to images and descriptions of the species, we included frequency data from large-volume plankton pump samples taken between 1998 and 2004 and time-series sediment trap samples from 2004-2005.
Detecting the influence of initial pioneers on succession at deep-sea vents

(Public Library of Science, 2012-12-04) Mullineaux, Lauren S. ; Le Bris, Nadine ; Mills, Susan W. ; Henri, Pauline ; Bayer, Skylar R. ; Secrist, Richard G. ; Siu, Nam

Deep-sea hydrothermal vents are subject to major disturbances that alter the physical and chemical environment and eradicate the resident faunal communities. Vent fields are isolated by uninhabitable deep seafloor, so recolonization via dispersal of planktonic larvae is critical for persistence of populations. We monitored colonization near 9°50′N on the East Pacific Rise following a catastrophic eruption in order to address questions of the relative contributions of pioneer colonists and environmental change to variation in species composition, and the role of pioneers at the disturbed site in altering community structure elsewhere in the region. Pioneer colonists included two gastropod species: Ctenopelta porifera, which was new to the vent field, and Lepetodrilus tevnianus, which had been rare before the eruption but persisted in high abundance afterward, delaying and possibly out-competing the ubiquitous pre-eruption congener L. elevatus. A decrease in abundance of C. porifera over time, and the arrival of later species, corresponded to a decrease in vent fluid flow and in the sulfide to temperature ratio. For some species these successional changes were likely due to habitat requirements, but other species persisted (L. tevnianus) or arrived (L. elevatus) in patterns unrelated to their habitat preferences. After two years, disturbed communities had started to resemble pre-eruption ones, but were lower in diversity. When compared to a prior (1991) eruption, the succession of foundation species (tubeworms and mussels) appeared to be delayed, even though habitat chemistry became similar to the pre-eruption state more quickly. Surprisingly, a nearby community that had not been disturbed by the eruption was invaded by the pioneers, possibly after they became established in the disturbed vents. These results indicate that the post-eruption arrival of species from remote locales had a strong and persistent effect on communities at both disturbed and undisturbed vents.
Desperate planktotrophs : decreased settlement selectivity with age in competent eastern oyster Crassostrea virginica larvae

( 2018-07) Meyer, Kirstin S. ; Wheeler, Jeanette D. ; Houlihan, Erin ; Mullineaux, Lauren S.

For larvae of benthic marine invertebrate species, settlement from planktonic to benthic life is a critical transition. The “desperate larva” concept describes the tendency of larvae to accept suboptimal settlement habitats as they age. We quantified swimming behavior in planktotrophic larvae of the eastern oyster, Crassostrea virginica, to determine whether settlement behaviors, such as swimming downward and remaining on the bottom, increased with age and whether these ontogenetic changes were more apparent in larvae exposed to suboptimal conditions than to preferred conditions (settlement cue absent or present, respectively). In two experiments, the proportion of competent larvae remaining near the bottom of experimental flasks (indicating settlement) increased with larval age, but only in larvae that were not exposed to the settlement cue. This result is consistent with the hypothesis that larvae encountering suboptimal habitat become “desperate” (i.e. more likely to settle) as they age. Exploratory behaviors, such as upward swimming, meandering, or helices, were expected to decrease with age, especially in the absence of the settlement cue, but this pattern was detected in only one of the five swimming metrics tested (helices in downward swimming larvae). Surprisingly, pre-competent larvae exhibited settlement behavior when exposed to the cue, raising the question of whether a response at this stage would have positive or negative consequences. Acceptance of suboptimal settlement habitats by aging larvae may increase the resilience of a species by allowing populations to persist in variable environmental conditions.
Active positioning of vent larvae at a mid-ocean ridge

( 2013-03) Mullineaux, Lauren S. ; McGillicuddy, Dennis J. ; Mills, Susan W. ; Kosnyrev, V. K. ; Thurnherr, Andreas M. ; Ledwell, James R. ; Lavelle, J. William

The vertical position of larvae of vent species above a mid-ocean ridge potentially has a strong effect on their dispersal. Larvae may be advected upward in the buoyant vent plume, or move as a consequence of their buoyancy or active swimming. Alternatively, they may be retained near bottom by the topography of the axial trough, or by downward swimming. At vents near 9°50’N on the axis of the East Pacific Rise, evidence for active larval positioning was detected in a comparison between field observations of larvae in the plankton in 2006 and 2007 and distributions of non-swimming larvae in a two-dimensional bio-physical model. In the field, few vent larvae were collected at the level of the neutrally buoyant plume (~75 m above bottom); their relative abundances at that height were much lower than those of simulated larvae from a near-bottom release in the model. This discrepancy was observed for many vent species, particularly gastropods, suggesting that they may actively remain near bottom by sinking or swimming downward. Near the seafloor, larval abundance decreased from the ridge axis to 1000 m off axis much more strongly in the observations than in the simulations, again pointing to behavior as a potential regulator of larval transport. We suspect that transport off axis was reduced by downward-moving behavior, which positioned larvae into locations where they were isolated from cross-ridge currents by seafloor topography, such as the walls of the axial valley – which are not resolved in the model. Cross-ridge gradients in larval abundance varied between gastropods and polychaetes, indicating that behavior may vary between taxonomic groups, and possibly between species. These results suggest that behaviorally mediated retention of vent larvae may be common, even for species that have a long planktonic larval duration and are capable of long-distance dispersal.
Larval responses to turbulence and temperature in a tidal inlet: Habitat selection by dispersing gastropods?

(Sears Foundation for Marine Research, 2010-06) Fuchs, Heidi L. ; Solow, Andrew R. ; Mullineaux, Lauren S.

Marine larval dispersal is affected by hydrodynamic transport and larval behavior, but little is known about how behavior affects large-scale patterns of dispersal and recruitment. Intertidal habitats are characterized by strong and variable turbulence relative to shelf and pelagic waters, so larval responses to turbulence may affect both dispersal and habitat selection. This study combined observations and theoretical approaches to model gastropod larval responses to multiple physical variables in a well-mixed tidal inlet. Physical measurements and larvae were collected in July 2004 in Barnstable Harbor, Massachusetts (USA). Physical measurements were incorporated in an advection-diffusion model where larval vertical velocity is a function of turbulence dissipation rate, temperature, and the temperature gradient. Modeled larval distributions were fitted to observed concentration profiles by maximum likelihood to estimate larval behavioral velocity (swimming or sinking) as a function of environmental conditions. These quantitative behavior estimates were used to test hypotheses about behavioral differences among groups and to assess the relative impact of different cues on overall larval behavior. Larvae of five common gastropod species from different coastal habitats reacted most strongly to turbulence but had genus-specific responses to environmental cues. Larvae of a species from tidal inlets (the mud snail Nassarius obsoletus) had near-zero velocities under calmer conditions and sank in strong turbulence. In contrast, larvae from exposed beach habitats (Crepidula spp. and Anachis spp.) sank in weak turbulence and swam up in strong turbulence, with additional responses to temperature and temperature gradient. Larval responses also differed between small and large size classes and between flood and ebb tides. Behavior of mud snail larvae would contribute to retention inside the inlet and near adult habitats, whereas behavior of beach snail larvae would contribute to rapid export from muddy inlets lacking suitable adult habitats.
Vertical, lateral and temporal structure in larval distributions at hydrothermal vents

(Inter-Research, 2005-06-02) Mullineaux, Lauren S. ; Mills, Susan W. ; Sweetman, Andrew K. ; Beaudreau, A. H. ; Metaxas, Anna ; Hunt, H. L.

We examined larval abundance patterns near deep-sea hydrothermal vents along the East Pacific Rise to investigate how physical transport processes and larval behavior may interact to influence larval dispersal from, and supply to, vent populations. We characterized vertical and lateral distributions and temporal variation of larvae of vent species using high-volume pumps that recovered larvae in good condition (some still alive) and in high numbers (up to 450 individuals sample–1). Moorings supported pumps at heights of 1, 20, and 175 m above the seafloor, and were positioned directly above and at 10s to 100s of meters away from vent communities. Sampling was conducted on 4 cruises between November 1998 and May 2000. Larvae of 22 benthic species, including gastropods, a bivalve, polychaetes, and a crab, were identified unequivocally as vent species, and 15 additional species, or species-groups, comprised larvae of probable vent origin. For most taxa, abundances decreased significantly with increasing height above bottom. When vent sites within the confines of the axial valley were considered, larval abundances were significantly higher on-vent than off, suggesting that larvae may be retained within the valley. Abundances of all vent species varied significantly among sample dates; the variation was not synchronized among taxa, except for consistently low abundances during November 1998. Lateral distributions did not vary among major larval groups (gastropods, polychaetes and bivalves), although polychaetes showed anomalously high abundances off-vent at 1 m above bottom. Lateral patterns also did not vary among species of gastropods, indicating that hydrodynamic processes may be transporting diverse species in similar ways. However, the species-level differences in temporal patterns indicate that there is substantial discontinuity in the abundance of individual species at vent communities, possibly due to timing of spawning and/or behavioral interactions with flow.
The prediction, verification, and significance of flank jets at mid-ocean ridges

(The Oceanography Society, 2012-03) Lavelle, J. William ; Thurnherr, Andreas M. ; Mullineaux, Lauren S. ; McGillicuddy, Dennis J. ; Ledwell, James R.

One aspect of ocean flow over mid-ocean ridges that has escaped much attention is the capacity of a ridge to convert oscillatory flows into unidirectional flows. Those unidirectional flows take the form of relatively narrow jets hugging the ridge's flanks. In the Northern Hemisphere, the jets move heat and dissolved and particulate matter poleward on the west and equatorward on the east of north-south trending ridges. Recent measurements and a model of flow at the East Pacific Rise at 9–10°N show that these ridge-parallel flows can extend 10–15 km horizontally away from the ridge axis, reach from the seafloor to several hundreds of meters above ridge crest depth, and have maximum speeds in their cores up to 10 cm s–1. Because of their along-ridge orientation and speed, the jets can significantly affect the transport of hydrothermal vent-associated larvae between vent oases along the ridge crest and, possibly, contribute to the mesoscale stirring of the abyssal ocean. Because jet-formation mechanisms involve oscillatory currents, ocean stratification, and topography, the jets are examples of "stratified topographic flow rectification." Ridge jets have parallels in rectified flows at seamounts and submarine banks.
Deep ocean circulation and transport where the East Pacific Rise at 9–10°N meets the Lamont seamount chain

(American Geophysical Union, 2010-12-31) Lavelle, J. William ; Thurnherr, Andreas M. ; Ledwell, James R. ; McGillicuddy, Dennis J. ; Mullineaux, Lauren S.

We report the first 3-D numerical model study of abyssal ocean circulation and transport over the steep topography of the East Pacific Rise (EPR) and adjoining Lamont seamount chain in the eastern tropical Pacific. We begin by comparing results of hydrodynamical model calculations with observations of currents, hydrography, and SF6 tracer dispersion taken during Larval Dispersal on the Deep East Pacific Rise (LADDER) field expeditions in 2006–2007. Model results are then used to extend observations in time and space. Regional patterns are pronounced in their temporal variability at M2 tidal and subinertial periods. Mean velocities show ridge-trapped current jets flowing poleward west and equatorward east of the ridge, with time-varying magnitudes (weekly average maximum of ∼10 cm s−1) that make the jets important features with regard to ridge-originating particle/larval transport. Isotherms bow upward over the ridge and plunge downward into seamount flanks below ridge crest depth. The passage (P1) between the EPR and the first Lamont seamount to the west is a choke point for northward flux at ridge crest depths and below. Weekly averaged velocities show times of anticyclonic flow around the Lamont seamount chain as a whole and anticyclonic flow around individual seamounts. Results show that during the LADDER tracer experiment SF6 reached P1 from the south in the western flank jet. A short-lived change in regional flow direction, just at the time of SF6 arrival at P1, started the transport of SF6 to the west on a course south of the seamounts, as field observations suggest. Approximately 20 days later, a longer-lasting shift in regional flow from west to SSE returned a small fraction of the tracer to the EPR ridge crest.
Persistent effects of disturbance on larval patterns in the plankton after an eruption on the East Pacific Rise

( 2013-07) Mills, Susan W. ; Mullineaux, Lauren S. ; Beaulieu, Stace E. ; Adams, Diane K.

To predict how benthic communities will respond to disturbance, it is necessary to understand how disturbance affects the planktonic larval supply available to recolonize the area. Deep-sea hydrothermal vent fauna along the East Pacific Rise (EPR) experience frequent local extinctions due to tectonic and magmatic events, but the effects on regional larval abundance and diversity are unknown. We had been monitoring larvae at 9° 50' N on the EPR prior to the 2006 eruption and were able to resume collections shortly afterward. We found that many species that were common before the eruption became significantly less so afterward, whereas a few other species experienced a transient spike in abundance. Surprisingly, overall species richness in the plankton was high 9 mo after the eruption, but then decreased sharply after 1 yr and had not returned to pre-eruption levels after 2 yr. These results suggest that recovery from disturbance may continue to be affected by limited larval supply even several years after a disturbance event. This delay in recovery means that larvae of pioneer species may dominate potential colonists, even after benthic habitats have transitioned to conditions that favor later-successional species. Moreover, the combined effects of natural and anthropogenic disturbance (e.g. mining) would be likely to cause more profound and long-lasting changes than either event alone. Our results indicate that we do not have sufficient data to predict the timing of recovery after disturbance in the deep sea, even in a well-studied vent system.
Biogeochemical exploration of the Pescardero Basin vents

(The Oceanography Society, 2018-03) Michel, Anna P. M. ; Wankel, Scott D. ; Beaulieu, Stace E. ; Soule, Samuel A. ; Mullineaux, Lauren S. ; Coleman, Dwight ; Escobar Briones, Elva ; Gaytan-Caballero, Adriana ; McDermott, Jill M. ; Mills, Susan W. ; Speth, Dan ; Zierenberg, Robert
Surface-generated mesoscale eddies transport deep-sea products from hydrothermal vents

( 2011-03) Adams, Diane K. ; McGillicuddy, Dennis J. ; Zamudio, Luis ; Thurnherr, Andreas M. ; Liang, Xinfeng ; Rouxel, Olivier J. ; German, Christopher R. ; Mullineaux, Lauren S.

Atmospheric forcing, which is known to have a strong influence on surface ocean dynamics and production, is typically not considered in studies of the deep sea. Our observations and models demonstrate an unexpected influence of surface-generated mesoscale eddies in the transport of hydrothermal vent efflux and of vent larvae away from the northern East Pacific Rise. Transport by these deep-reaching eddies provides a mechanism for spreading the hydrothermal chemical and heat-flux into the deep-ocean interior and for dispersing propagules hundreds of kilometers between isolated and ephemeral communities. Since the eddies interacting with the East Pacific Rise are formed seasonally and are sensitive to phenomena such as El Niño, they have the potential to introduce seasonal to interannual atmospheric variations into the deep sea.
Temperature and salinity effects on elemental uptake in the shells of larval and juvenile softshell clams Mya arenaria

(Inter-Research, 2008-10-28) Strasser, Carly A. ; Mullineaux, Lauren S. ; Thorrold, Simon R.

The chemical composition of biogenic carbonate has great potential to serve as a natural tag in studies of marine population connectivity. Yet the degree to which carbonate chemistry reflects ambient water composition may be influenced by environmental parameters, physiology, and uptake kinetics. We explored the effects of temperature and salinity on the uptake of elements into shells of larval and juvenile softshell clams Mya arenaria. Clams were reared under controlled conditions using combinations of temperatures (15, 20, and 24°C) and salinities (22 and 30‰) commonly encountered in their natural habitat. We analyzed the ratios of a suite of elements (Mg, Mn, Sr, Ba and Pb) to Ca in seawater and shells using solution-based inductively coupled plasma-mass spectrometry (ICP-MS). Elemental ratios were translated into discrimination coefficients (Delement) to account for water chemistry variability among treatments. For larval shell, we found that DMn was lower in the low-temperature treatment than at higher temperatures, had mixed results for correlations with salinity, and exhibited an interactive effect between salinity and temperature. We also found that DBa of larval shell was higher in the 15°C treatment than at the other 2 temperatures. In juvenile shell, we found a temperature effect for DMn, however the exact relationship was unclear because DMn was higher in the mid-temperature treatment than either the low- or high-temperature treatments. DSr was negatively correlated with salinity in juveniles, with evidence of an interactive effect for temperature and salinity. DBa and DPb were both higher in juveniles in the low-temperature treatment than in the 2 higher temperatures. When discrimination coefficients significantly differed based on ANOVA, we used post hoc comparisons to further explore the effects of temperature and salinity. Correlation analyses showed that uptake differed significantly between larval and juvenile M. arenaria shell for all elements, with no predictable relationship in shell uptake between the 2 stages except for DBa. All of the elements examined in this study have the potential to be useful in tagging studies where geographic variability in temperature, salinity or elemental concentrations exists, although caution should be used to ensure any biological interactions with these variables are accounted for in data interpretation.
Hydrography and circulation near the crest of the East Pacific Rise between 9° and 10°N

( 2010-12-12) Thurnherr, Andreas M. ; Ledwell, James R. ; Lavelle, J. William ; Mullineaux, Lauren S.

Topography has a strong effect on the physical oceanography over the flanks and crests of the global mid-ocean ridge system. Here, we present an analysis of the hydrography and circulation near the crest of the East Pacific Rise (EPR) between 9◦ and 10◦N, which coincides with an integrated study site (ISS) of the RIDGE2000 program. The analysis is based primarily on survey and mooring data collected during the LADDER project, which aimed to investigate oceanographic and topographic influences on larval retention and dispersal in hydrothermal vent communities. Results indicate that the yearly averaged regional mean circulation is characterized by a westward drift of 0.5–1 cm·s−1 across the EPR axis and by north- and southward flows along the western and eastern upper ridge flanks, respectively. The westward drift is part of a basin-scale zonal flow that extends across most of the Pacific ocean near 10◦N, whereas the meridional currents near the ridge crest are a topographic effect. In spite of considerable mesoscale variability, which dominates the regional circulation and dispersal on weekly to monthly time scales, quasi-synoptic surveys carried out during the mooring deployment and recovery cruises indicate subinertial circulations that are qualitatively similar to the yearly averaged flow but associated with significantly stronger velocities. Weekly averaged mooring data indicate that the anticyclonically sheared along-flank flows are associated with core speeds as high as 10 cm·s−1 and extend ≈10 km off axis and 200m above the ridge-crest topography. Near the northern limit of the study region, the Lamont Seamount Chain rises from the western ridge flank and restricts along-EPR flow to five narrow passages, where peak velocities in excess of 20 cm·s−1 were observed. Outside the region of the ridge-crest boundary currents the density field over the EPR near 10◦N is characterized by isopycnals dipping into the ridge flanks. Directly above the EPR axis the ridge-crest boundary currents give rise to an isopycnal dome. During times of strong westward cross-EPR flow isopycnal uplift over the eastern flank causes the cross-ridge density field below the doming isopycnals to be asymmetric, with higher densities over the eastern than over the western flank. The data collected during the LADDER project indicate that dispersal of hydrothermal products from the EPR ISS on long time scales is predominantly to the west, whereas mesoscale variability dominates dispersal on weekly to monthly time scales, which are particularly important in the context of larval dispersal.
Larval dispersion along an axially symmetric mid-ocean ridge

( 2009-12-22) McGillicuddy, Dennis J. ; Lavelle, J. William ; Thurnherr, Andreas M. ; Kosnyrev, V. K. ; Mullineaux, Lauren S.

We investigated planktonic larval transport processes along an axially symmetric mid-ocean ridge with characteristics similar to that of the East Pacific Rise (EPR) segment at 9-10°N. The hydrodynamic basis for this study is a primitive equation model implemented in two dimensions (depth and across-ridge), forced at the open boundaries to provide suitably realistic simulation of currents observed on the EPR ridge crest from May to November 1999. Three-dimensional trajectories of numerical larvae are computed assuming homogeneity in currents in the along-ridge direction. Larval dispersal fluctuates significantly in time. Transport distance decreases systematically with height above the bottom where numerical larvae are less subject to strong currents along the flanks of the ridge. The probability that the simulated larvae will be located near the ridge crest at settlement depends strongly on their behavioral characteristics (vertical position in the water column during the larval stage) and the length of their precompetency period.
Prolonged recovery time after eruptive disturbance of a deep-sea hydrothermal vent community

(The Royal Society, 2020-12-23) Mullineaux, Lauren S. ; Mills, Susan W. ; Le Bris, Nadine ; Beaulieu, Stace E. ; Sievert, Stefan M. ; Dykman, Lauren

Deep-sea hydrothermal vents are associated with seafloor tectonic and magmatic activity, and the communities living there are subject to disturbance. Eruptions can be frequent and catastrophic, raising questions about how these communities persist and maintain regional biodiversity. Prior studies of frequently disturbed vents have led to suggestions that faunal recovery can occur within 2–4 years. We use an unprecedented long-term (11-year) series of colonization data following a catastrophic 2006 seafloor eruption on the East Pacific Rise to show that faunal successional changes continue beyond a decade following the disturbance. Species composition at nine months post-eruption was conspicuously different than the pre-eruption ‘baseline' state, which had been characterized in 1998 (85 months after disturbance by the previous 1991 eruption). By 96 months post-eruption, species composition was approaching the pre-eruption state, but continued to change up through to the end of our measurements at 135 months, indicating that the ‘baseline' state was not a climax community. The strong variation observed in species composition across environmental gradients and successional stages highlights the importance of long-term, distributed sampling in order to understand the consequences of disturbance for maintenance of a diverse regional species pool. This perspective is critical for characterizing the resilience of vent species to both natural disturbance and human impacts such as deep-sea mining.
Functional traits provide new insight into recovery and succession at deep-sea hydrothermal vents

(Ecological Society of America, 2021-05-28) Dykman, Lauren ; Beaulieu, Stace E. ; Mills, Susan W. ; Solow, Andrew R. ; Mullineaux, Lauren S.

Investigation of communities in extreme environments with unique conditions has the potential to broaden or challenge existing theory as to how biological communities assemble and change through succession. Deep-sea hydrothermal vent ecosystems have strong, parallel gradients of nutrients and environmental stress, and present unusual conditions in early succession, in that both nutrient availability and stressors are high. We analyzed the succession of the invertebrate community at 9°50′ N on the East Pacific Rise for 11 yr following an eruption in 2006 in order to test successional theories developed in other ecosystems. We focused on functional traits including body size, external protection, provision of habitat (foundation species), and trophic mode to understand how the unique nutritional and stress conditions influence community composition. In contrast to established theory, large, fast-growing, structure-forming organisms colonized rapidly at vents, while small, asexually reproducing organisms were not abundant until later in succession. Species in early succession had high external protection, as expected in the harsh thermal and chemical conditions after the eruption. Changes in traits related to feeding ecology and dispersal potential over succession agreed with expectations from other ecosystems. We also tracked functional diversity metrics over time to see how they compared to species diversity. While species diversity peaked at 8 yr post-eruption, functional diversity was continuing to increase at 11 yr. Our results indicate that deep-sea hydrothermal vents have distinct successional dynamics due to the high stress and high nutrient conditions in early succession. These findings highlight the importance of extending theory to new systems and considering function to allow comparison between ecosystems with different species and environmental conditions.
Habitat associations in gastropod species at East Pacific Rise hydrothermal vents (9°50'N)

(Marine Biological Laboratory, 2007-06) Mills, Susan W. ; Mullineaux, Lauren S. ; Tyler, Paul A.

At deep-sea hydrothermal vents on the East Pacific Rise (9°50'N), distinct megafaunal assemblages are positioned along strong thermal and chemical gradients. We investigated the distribution of gastropod species to determine whether they associate with specific megafaunal zones and to determine the thermal boundaries of their habitats. Gastropods colonized a series of basalt blocks that were placed into three different zones characterized by vestimentiferan tubeworms, bivalves, and suspension-feeders, respectively. Additional gastropods were collected on selected blocks from higher temperature vestimentiferan habitat and from grab samples of alvinellid polychaetes. On the blocks, gastropod species clustered into a "Cool" group (Clypeosectus delectus, Eulepetopsis vitrea, Gorgoleptis spiralis, and Lepetodrilus ovalis) whose species tended to be most abundant in the suspension-feeder zone, and a "Warm" group (Lepetodrilus cristatus, L. elevatus, L. pustulosus, and Cyathermia naticoides) whose species all were significantly more abundant in the vestimentiferan zone than elsewhere. The temperature ranges of Cool species were generally lower than the ranges of Warm ones, although both groups were present at 3 to 6 °C; also present was Bathymargarites symplector, which clustered with neither group. Three additional species, Rhynchopelta concentrica, Neomphalus fretterae, and Nodopelta rigneae, co-occurred with Warm-group species on selected blocks from hotter habitats. Although a few species were found only in alvinellid collections, most species were not exclusive to a specific megafaunal zone. We propose that species in the Cool and Warm groups occupy specific microhabitats that are present in more than one zone.
Bacterial group II introns in a deep-sea hydrothermal vent environment

(American Society for Microbiology, 2002-12) Podar, Mircea ; Mullineaux, Lauren S. ; Huang, Hon-Ren ; Perlman, Philip S. ; Sogin, Mitchell L.

Group II introns are catalytic RNAs and mobile retrotransposable elements known to be present in the genomes of some nonmarine bacteria and eukaryotic organelles. Here we report the discovery of group II introns in a bacterial mat sample collected from a deep-sea hydrothermal vent near 9°N on the East Pacific Rise. One of the introns was shown to self-splice in vitro. This is the first example of marine bacterial introns from molecular population structure studies of microorganisms that live in the proximity of hydrothermal vents. These types of mobile genetic elements may prove useful in improving our understanding of bacterial genome evolution and may serve as valuable markers in comparative studies of bacterial communities.
Introduction to the special issue : From RIDGE to Ridge 2000

(The Oceanography Society, 2012-03) Fornari, Daniel J. ; Beaulieu, Stace E. ; Holden, James F. ; Mullineaux, Lauren S. ; Tolstoy, Maya

Articles in this special issue of Oceanography represent a compendium of research that spans the disciplinary and thematic breadth of the National Science Foundation's Ridge 2000 Program, as well as its geographic focal points. The mid-ocean ridge (MOR) crest is where much of Earth's volcanism is focused and where most submarine volcanic activity occurs. If we could look down from space at our planet with the ocean drained, the MOR's topography and shape, along with its intervening fracture zones, would resemble the seams on a baseball, with the ocean basins dominating our planetary panorama. The volcanic seafloor is hidden beneath the green-blue waters of the world's ocean, yet therein lie fundamental clues to how our planet works and has evolved over billions of years, something that was not clearly understood 65 years ago—witness the following quote from H.H. Hess (1962) in his essay on "geopoetry" and commentary on J.H.F. Umbgrove's (1947) comprehensive summary of Earth and ocean history: The birth of the oceans is a matter of conjecture, the subsequent history is obscure, and the present structure is just beginning to be understood. Fascinating speculation on these subjects has been plentiful, but not much of it predating the last decade [the 1950s] holds water.
Colonisation of newly-opened habitat by a pioneer species, Alvinella pompejana (Polychaeta: Alvinellidae), at East Pacific Rise vent sites

(Inter-Research, 2005-11-04) Pradillon, Florence ; Zbinden, Magali ; Mullineaux, Lauren S. ; Gaill, Francoise

Animal communities on the walls of deep-sea hydrothermal chimneys are distributed in mosaics of patches that may evolve as local environmental conditions change and biological interactions develop. Alvinella pompejana Desbruyères et Laubier, 1980 is one of the first metazoan colonisers of new surfaces created by mineral precipitation, and therefore may be particularly important in community establishment in active parts of smokers. Here our goal was to investigate the colonisation mechanisms of A. pompejana in new patches and determine whether these mechanisms may influence population structure and reproductive patterns in this species. We deployed a series of TRAC (Titanium Ring for Alvinellid Colonisation) devices at East Pacific Rise (EPR) vent sites to compare the size and stage (i.e. reproductive maturity) distribution of A. pompejana individuals between recently colonised patches (TRACs) and established patches (grabbed by submersible). TRACs deployed for short time periods (11 d to 1 mo) were generally colonised by smaller individuals than those found in background populations or in TRACs deployed for longer time periods (>1 mo). Colonists into new patches were a mix of juveniles and individuals that were sexually mature but non-reproductive (i.e. not producing gametes), whereas background population and older patches harboured a mixture of individuals at different stages including reproductive females. Although some individuals may have recruited on TRACs as larvae, the major colonisation process involved was probably immigration of post-larval stages. In long-term TRAC, reproductive females were not reproductively synchronised. In this dynamic environment, reproduction would be triggered by the disturbance/migration processes, explaining the heterogeneity observed in reproductive patterns.

Mullineaux Lauren S.

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