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Gage, JD, Levin LA, Wolff GA.  2000.  Benthic processes in the deep Arabian Sea: introduction and overview. Deep-Sea Research Part Ii-Topical Studies in Oceanography. 47:1-7.   10.1016/S0967-0645(99)00095-8   AbstractWebsite
Gallardo, VA, Palma M, Carrasco FD, Gutierrez D, Levin LA, Canete JI.  2004.  Macrobenthic zonation caused by the oxygen minimum zone on the shelf and slope off central Chile. Deep-Sea Research Part Ii-Topical Studies in Oceanography. 51:2475-2490.   10.1016/j.dsr2.2004.07.028   AbstractWebsite

The relationship between macrobenthic (greater than or equal to 300 mum) zonation and the oxygen minimum zone (OMZ: O(2) < 0.5 ml L(-1)) was studied in shelf and slope sediments (122-840 m depth) off Concepcion Bay, central Chile. Four study sites were sampled during March-April 1999 for abiotic factors, macrofaunal density, biomass, mean individual size, and diversity. Within the OMZ (122-206 m), the macrofaunal density was high (16,478-21,381 individuals m(-2)) and 69-89% of the organisms were soft-bodied. Density was highest (21,381 individuals m(-2)), biomass lowest (16.95 g wet weight m-2), and individual size smallest (0.07 mg C individuals) at the shelf break site (206 m). Polychaete worms made up 71% of the total abundance, crustaceans 16%, and mollusks only 2%. Total abundance beneath the OMZ (mid-slope site, similar to840 m) was 49% crustaceans and 43% polychaetes. Although existing literature originally led to the hypothesis that both diversity and biomass within the OMZ would be lower than beneath the OMZ, in the present study this was only true for diversity. Biomass distribution, on the other hand, was concave along the depth gradient; the highest values were near the upper edge of (122 m) and beneath (840 m) the OMZ. Indices of the macrofaunal community structure varied in relation to bottom-water oxygen concentration, chlorophyll-alpha, phaeopigments, and sulfide concentration, but not in relation to grain size, C, N, mud, porosity, redox potential, a bottom-water temperature. (C) 2004 Published by Elsevier Ltd.

Gallo, ND, Levin LA.  2016.  Fish ecology and evolution in the world's oxygen minimum zones and implications of ocean deoxygenation. Advances in Marine Biology, Vol 74. 74( Curry BE, Ed.).:117-198., San Diego: Elsevier Academic Press Inc   10.1016/bs.amb.2016.04.001   Abstract

Oxygen minimum zones (OMZs) and oxygen limited zones (OLZs) are important oceanographic features in the Pacific, Atlantic, and Indian Ocean, and are characterized by hypoxic conditions that are physiologically challenging for demersal fish. Thickness, depth of the upper boundary, minimum oxygen levels, local temperatures, and diurnal, seasonal, and interannual oxycline variability differ regionally, with the thickest and shallowest OMZs occurring in the subtropics and tropics. Although most fish are not hypoxia-tolerant, at least 77 demersal fish species from 16 orders have evolved physiological, behavioural, and morphological adaptations that allow them to live under the severely hypoxic, hypercapnic, and at times sulphidic conditions found in OMZs. Tolerance to OMZ conditions has evolved multiple times in multiple groups with no single fish family or genus exploiting all OMZs globally. Severely hypoxic conditions in OMZs lead to decreased demersal fish diversity, but fish density trends are variable and dependent on region-specific thresholds. Some OMZ-adapted fish species are more hypoxiatolerant than most megafaunal invertebrates and are present even when most invertebrates are excluded. Expansions and contractions of OMZs in the past have affected fish evolution and diversity. Current patterns of ocean warming are leading to ocean deoxygenation, causing the expansion and shoaling of OMZs, which is expected to decrease demersal fish diversity and alter trophic pathways on affected margins. Habitat compression is expected for hypoxia-intolerant species, causing increased susceptibility to overfishing for fisheries species. Demersal fisheries are likely to be negatively impacted overall by the expansion of OMZs in a warming world.

Gallo, ND, Victor DG, Levin LA.  2017.  Ocean commitments under the Paris Agreement. Nature Climate Change. 7:833-+.   10.1038/nclimate3422   AbstractWebsite

Under the Paris Agreement nations made pledges known as nationally determined contributions (NDCs), which indicate how national governments are evaluating climate risks and policy opportunities. We find that NDCs reveal important systematic patterns reflecting national interests and capabilities. Because the ocean plays critical roles in climate mitigation and adaptation, we created a quantitative marine focus factor (MFF) to evaluate how governments address marine issues. In contrast to the past, when oceans received minimal attention in climate negotiations, 70% of 161 NDCs we analysed include marine issues. The percentage of the population living in low-lying areas-vulnerable to rising seas-positively influences the MFF, but negotiating group (Annex 1 or small island developing states) is equally important, suggesting political motivations are crucial to NDC development. The analysis reveals gaps between scientific and government attention, including on ocean deoxygenation, which is barely mentioned. Governments display a keen interest in expanding marine research on climate priorities.

Gallo, ND, Cameron J, Hardy K, Fryer P, Bartlett DH, Levin LA.  2015.  Submersible- and lander-observed community patterns in the Mariana and New Britain trenches: Influence of productivity and depth on epibenthic and scavenging communities. Deep-Sea Research Part I-Oceanographic Research Papers. 99:119-133.   10.1016/j.dsr.2014.12.012   AbstractWebsite

Deep-sea trenches remain one of the least explored ocean ecosystems due to the unique challenges of sampling at great depths. Five submersible dives conducted using the DEEPSEA CHALLENGER submersible generated video of undisturbed deep-sea communities at bathyal (994 m), abyssal (3755 m), and hadal (8228 m) depths in the New Britain Trench, bathyal depths near the Ulithi atoll (1192 m), and hadal depths in the Mariana Trench Challenger Deep (10908 m). The New Britain Trench is overlain by waters with higher net primary productivity (similar to 3-fold) than the Mariana Trench and nearby Ulithi, and receives substantially more allochthonous input from terrestrial sources, based on the presence of terrestrial debris in submersible video footage. Comparisons between trenches addressed how differences in productivity regime influence benthic and demersal deep-sea community structure. In addition, the scavenger community was studied using paired lander deployments to the New Britain (8233 m) and Mariana (10918 m) trenches. Differences in allochthonous input were reflected in epibenthic community abundance, biodiversity, and lifestyle representation. More productive locations were characterized by higher faunal abundances (similar to 2-fold) at both bathyal and hadal depths. In contrast, biodiversity trends showed a unimodal pattern with more food-rich areas exhibiting reduced bathyal diversity and elevated hadal diversity. Hadal scavenging communities exhibited similar higher abundance but also similar to 3-fold higher species richness in the more food-rich New Britain Trench compared to the Mariana Trench. High species- and phylum-level diversity observed in the New Britain Trench suggest that trench environments may foster higher megafaunal biodiversity than surrounding abyssal depths if food is not limiting. However, the absence of fish at our hadal sites suggests that certain groups do have physiological depth limits. Submersible video footage allowed novel in situ observation of holothurian orientation, jellyfish feeding behavior as well as lifestyle preferences for substrate, seafloor and overlying water. This study documents previously unreported species in the New Britain Trench, including an ulmariid scyphozoan (8233 m) and an acrocirrid polychaete (994 m), and reports the first observation of an abundant population of elpidiid holothurians in the Mariana Trench (10908 m). It also provides the first megafaunal community analysis of the world's deepest epibenthic community in the Mariana Trench Challenger Deep, which was composed of elpidiid holothurians, amphipods, and xenophyophores. (C) 2015 The Authors. Published by Elsevier Ltd.

Gooday, AJ, Bett BJ, Escobar E, Ingole B, Levin LA, Neira C, Raman AV, Sellanes J.  2010.  Habitat heterogeneity and its influence on benthic biodiversity in oxygen minimum zones. Marine Ecology-an Evolutionary Perspective. 31:125-147.   10.1111/j.1439-0485.2009.00348.x   AbstractWebsite

Oxygen minimum zones (OMZs; midwater regions with O(2) concentrations <0.5 ml l(-1)) are mid-water features that intercept continental margins at bathyal depths (100-1000 m). They are particularly well developed in the Eastern Pacific Ocean, the Arabian Sea and the Bay of Bengal. Based on analyses of data from these regions, we consider (i) how benthic habitat heterogeneity is manifested within OMZs, (ii) which aspects of this heterogeneity exert the greatest influence on alpha and beta diversity within particular OMZs and (iii) how heterogeneity associated with OMZs influences regional (gamma) diversity on continental margins. Sources of sea-floor habitat heterogeneity within OMZs include bottom-water oxygen and sulphide gradients, substratum characteristics, bacterial mats, and variations in the organic matter content of the sediment and pH. On some margins, hard grounds, formed of phosphorites, carbonates or biotic substrata, represent distinct subhabitats colonized by encrusting faunas. Most of the heterogeneity associated with OMZs, however, is created by strong sea-floor oxygen gradients, reinforced by changes in sediment characteristics and organic matter content. For the Pakistan margin, combining these parameters revealed clear environmental and faunal differences between the OMZ core and the upper and lower boundary regions. In all Pacific and Arabian Sea OMZs examined, oxygen appears to be the master driver of alpha and beta diversity in all benthic faunal groups for which data exist, as well as macrofaunal assemblage composition, particularly in the OMZ core. However, other factors, notably organic matter quantity and quality and sediment characteristics, come into play as oxygen concentrations begin to rise. The influence of OMZs on meiofaunal, macrofaunal and megafaunal regional (gamma) diversity is difficult to assess. Hypoxia is associated with a reduction in species richness in all benthic faunal groups, but there is also evidence for endemism in OMZ settings. We conclude that, on balance, OMZs probably enhance regional diversity, particularly in taxa such as Foraminifera, which are more tolerant of hypoxia than others. Over evolutionary timescales, they may promote speciation by creating strong gradients in selective pressures and barriers to gene flow.

Gooday, AJ, Jorissen F, Levin LA, Middelburg JJ, Naqvi SWA, Rabalais NN, Scranton M, Zhang J.  2009.  Historical records of coastal eutrophication-induced hypoxia. Biogeosciences. 6:1707-1745.   10.5194/bg-6-1707-2009   AbstractWebsite

Under certain conditions, sediment cores from coastal settings subject to hypoxia can yield records of environmental changes over time scales ranging from decades to millennia, sometimes with a resolution of as little as a few years. A variety of biological and geochemical indicators (proxies) derived from such cores have been used to reconstruct the development of eutrophication and hypoxic conditions over time. Those based on (1) the preserved remains of benthic organisms (mainly foraminiferans and ostracods), (2) sedimentary features (e.g. laminations) and (3) sediment chemistry and mineralogy (e.g. presence of sulphides and redox-sensitive trace elements) reflect conditions at or close to the seafloor. Those based on (4) the preserved remains of planktonic organisms (mainly diatoms and dinoflagellates), (5) pigments and lipid biomarkers derived from prokaryotes and eukaryotes and (6) organic C, N and their stable isotope ratios reflect conditions in the water column. However, the interpretation of these indicators is not straightforward. A central difficulty concerns the fact that hypoxia is strongly correlated with, and often induced by, organic enrichment caused by eutrophication, making it difficult to separate the effects of these phenomena in sediment records. The problem is compounded by the enhanced preservation in anoxic and hypoxic sediments of organic microfossils and biomarkers indicating eutrophication. The use of hypoxia-specific proxies, such as the trace metals molybdenum and rhenium and the bacterial biomarker isorenieratene, together with multi-proxy approaches, may provide a way forward. All proxies of bottom-water hypoxia are basically qualitative; their quantification presents a major challenge to which there is currently no satisfactory solution. Finally, it is important to separate the effects of natural ecosystem variability from anthropogenic effects. Despite these problems, in the absence of historical data for dissolved oxygen concentrations, the analysis of sediment cores can provide plausible reconstructions of the temporal development of human-induced hypoxia, and associated eutrophication, in vulnerable coastal environments.

Gooday, AJ, Bernhard JM, Levin LA, Suhr SB.  2000.  Foraminifera in the Arabian Sea oxygen minimum zone and other oxygen-deficient settings: taxonomic composition, diversity, and relation to metazoan faunas. Deep-Sea Research Part Ii-Topical Studies in Oceanography. 47:25-54.   10.1016/s0967-0645(99)00099-5   AbstractWebsite

Previous work has shown that some foraminiferal species thrive in organically enriched, oxygen-depleted environments. Here, we compare 'live' (stained) faunas in multicorer samples (0-1 cm layer) obtained at two sites on the Oman margin, one located at 412m within the oxygen minimum zone (OMZ) (O(2) = 0.13 ml l(-1)), the other located at 3350 m, well below the main OMZ (O(2) similar to 3.00 ml l(-1)). While earlier studies have focused on the hard-shelled (predominantly calcareous) foraminifera, we consider complete stained assemblages, including poorly known, soft-shelled, monothalamous forms. Densities at the 412-m site were much higher (16,107 individuals.10 cm(-2) in the > 63-mu m fraction) than at the 3350-m site (625 indiv.10 cm(-2)). Species richness (E(S(100))), diversity (H', Fishers Alpha index) and evenness (J') were much lower, and dominance (R1D) was higher, at 412 m compared with 3350 m. At 412 m, small calcareous foraminifera predominated and soft-shelled allogromiids and sacamminids were a minor faunal element. At 3350 m, calcareous individuals were much less common and allogromiids and saccamminids formed a substantial component of the fauna. There were also strong contrasts between the foraminiferal macrofauna( > 300-mu m fraction) at these two sites; relatively small species of Bathysiphon, Globobulimina and Lagenammina dominated at 412 m, very large, tubular, agglutinated species of Bathysiphon, Hyperammina, Rhabdammina and Saccorhiza were important at 3350 m. Our observations suggest that, because they contain fewer soft-shelled and agglutinated foraminifera, a smaller proportion of bathyal, low-oxygen faunas is lost during fossilization compared to faunas from well-oxygenated environments. Trends among foraminifera (> 63 mu m fraction) in the Santa Barbara Basin (590 and 610m depth; O(2) = 0.05 and 0.15 ml(-1) respectively), and macrofaunal foraminifera(> 300 mu m) on the Peru margin (300-1250 m depth: O(2) = 0.02-1.60 mi l(-1)), matched those observed on the Oman margin. Tn particular, soft-shelled monothalamous taxa were rare and large agglutinated taxa were absent in the most oxygen-depleted ( < 0.20 mi l(-1)) stations. Foraminifera often outnumber metazoans (both meiofaunal and macrofaunal) in bathyal oxygen-depleted settings. However, although phylogenetically distant, foraminifera and metazoans exhibit similar population responses to oxygen depletion; species diversity decreases, dominance increases, and the relative abundance of the major taxa changes. The foraminiferal macrofauna ( > 300 mu m) were 5 times more abundant than the metazoan macrofauna at 412 m on the Oman margin but 16 times more abundant at the 3350 m site. Among the meiofauna (63-300 mu m), the trend was reversed, foraminifera were 17 times more abundant than metazoan taxa at 412 m but only 1.4 times more abundant at 3350 In. An abundance of food combined with oxygen levels which are not depressed sufficiently to eliminate the more tolerant taxa, probably explains why foraminifera and macrofaunal metazoans flourished at the 412-m site, perhaps to the detriment of the metazoan meiofauna. (C) 1999 Elsevier Science Ltd. All rights reserved.

Gooday, AJ, Levin LA, Linke P, Heeger T.  1992.  The role of benthic foraminifera in Deep-sea food webs and carbon cycling. Deep-sea food chains and the global carbon cycle. ( Rowe GT, Pariente V, Eds.).:63-91., Dordrecht ; Boston: Kluwer Academic Publishers Abstract
Gooday, AJ, Levin LA, da Silva AA, Bett BJ, Cowie GL, Dissard D, Gage JD, Hughes DJ, Jeffreys R, Lamont PA, Larkin KE, Murty SJ, Schumacher S, Whitcraft C, Woulds C.  2009.  Faunal responses to oxygen gradients on the Pakistan margin: A comparison of foraminiferans, macrofauna and megafauna. Deep-Sea Research Part Ii-Topical Studies in Oceanography. 56:488-502.   10.1016/j.dsr2.2008.10.003   AbstractWebsite

The Pakistan Margin is characterised by a strong mid-water oxygen minimum zone (OMZ) that intercepts the seabed at bathyal depths (150-1300 m). We investigated whether faunal abundance and diversity trends were similar among protists (foraminiferans and gromiids), metazoan macrofauna and megafauna along a transect (140-1850 m water depth) across the OMZ during the 2003 intermonsoon (March-May) and late/post-monsoon (August-October) seasons. All groups exhibited some drop in abundance in the OMZ core (250-500 m water depth; O(2): 0.10-0.13 mL L(-1) = 4.46-5.80 mu M) but to differing degrees. Densities of foraminiferans >63 mu m were slightly depressed at 300 m, peaked at 738 m, and were much lower at deeper stations. Foraminiferans >300 mu m were the overwhelmingly dominant macrofaunal organisms in the OMZ core. Macrofaunal metazoans reached maximum densities at 140 m depth, with additional peaks at 850, 940 and 1850 m where foraminiferans were less abundant. The polychaete Linopherus sp. was responsible for a macrofaunal biomass peak at 950 m. Apart from large swimming animals (fish and natant decapods), metazoan megafauna were absent between 300 and 900 m (O(2) <0.14-0.15 mLL(-1) = 6.25-6.69 mu M) but were represented by a huge, ophiuroid-dominated abundance peak at 1000 m (O(2) similar to 0.15-0.18 mLL(-1) = 6.69-8.03 mu M). Gromiid protists were confined largely to depths below 1150 m (O(2) > 0.2 mLL(-1) = 8.92 mu M). The progressively deeper abundance peaks for foraminiferans (> 63 mu m), Linopherus sp. and ophiuroids probably represent lower OMZ boundary edge effects and suggest a link between body size and tolerance of hypoxia. Macro- and megafaunal organisms collected between 800 and 1100 m were dominated by a succession of different taxa, indicating that the lower part of the OMZ is also a region of rapid faunal change. Species diversity was depressed in all groups in the OMZ core, but this was much more pronounced for macrofauna and megafauna than for foraminiferans. Oxygen levels strongly influenced the taxonomic composition of all faunal groups. Calcareous foraminiferans dominated the seasonally and permanently hypoxic sites (136-300 m); agglutinated foraminiferans were relatively more abundant at deeper stations where oxygen concentrations were >0.13 mLL(-1)( = 5.80 mu M). Polychaetes were the main macrofaunal taxon within the OMZ; calcareous macrofauna, and megafauna (molluscs and echinoderms) were rare or absent where oxygen levels were lowest. The rarity of larger animals between 300 and 700 m on the Pakistan Margin, compared with the abundant macrofauna in the OMZ core off Oman, is the most notable contrast between the two sides of the Arabian Sea. This difference probably reflects the slightly higher oxygen levels and better food quality on the western side. (C) 2008 Published by Elsevier Ltd.

Gooday, AJ, Hughes JA, Levin LA.  2001.  The foraminiferan macrofauna from three North Carolina (USA) slope sites with contrasting carbon flux: a comparison with the metazoan macrofauna. Deep-Sea Research Part I-Oceanographic Research Papers. 48:1709-1739.   10.1016/s0967-0637(00)00098-4   AbstractWebsite

Food supply exerts a strong influence on benthic faunal abundance and community structure. Here, we compare community-level responses of macrofaunal foraminiferans and metazoans ( > 300 mum fraction) in relation to a gradient of organic carbon flux [Site III > II > I] along the 850 m contour on the North Carolina slope. Foraminiferan density, species richness E(S(100)), and dominance were positively correlated with organic carbon flux;. Foraminiferans were more abundant at Site III, displayed lower diversity and higher dominance, and tended to live deeper in the sediment column than at either Sites I or II. The Site I fauna was dominated by agglutinated taxa (mainly simple monothalamous forms and hormosinaceans) and included large epifaunal species, some of which projected from the sediment surface and probably fed on fresh phytodetritus. Hormosinaceans and monothalamous taxa also were abundant at Site II, although large epifaunal taxa were not present. The Site III fauna was dominated by calcareous tare. The most abundant species was Globobulimina auriculata, an infaunal, low-oxygen tolerant, deposit feeder with a calcareous test sometimes obscured by an agglutinated cyst. Plate-like or flattened fragments of small xenophyophore species occurred at Site I, an unusually shallow record for this taxon and the first from the North Carolina margin. Most of these fragments were dead. Xenophyophores were not present at Sites II and III. The metazoan macrofauna exhibited trends in density, diversity, dominance and vertical distribution within the sediment that parallel those of the foraminiferans and were correlated with between-site differences in food availability. However, metazoans were 4.5-6.5 times less abundant than the foraminiferans, were more diverse, exhibited lower dominance and (at least at Sites I and III) tended to penetrate the sediment less deeply, These differences suggest that foraminiferans, considered as a group, are more opportunistic than metazoans, tolerate oxygen depletion better, and have population dynamics that are more closely coupled to organic matter inputs than those of metazoans. Foraminiferan diversity trends are even more similar to those of the polychaetes at these sites, suggesting that there are ecological parallels between the two taxa despite their fundamental phylogenetic and structural differences. Foraminiferans are a ubiquitous yet frequently overlooked component of the macrofauna on continental margins that experience a broad range of organic input regimes. They deserve to be considered more often in macrofaunal studies addressing interactions between organisms and their environments. (C) 2001 Elsevier Science Ltd. All rights reserved.

Gooday, AJ, Levin LA, Thomas CL, Hecker B.  1992.  The distribution and ecology of Bathysiphon filiformis sars and B. major de folin (Protista, Foraminiferida) on the continental slope off North Carolina. Journal of Foraminiferal Research. 22:129-146. AbstractWebsite

Two large species of the agglutinated foraminifera genus Bathysiphon are common in samples and photographs from bathyal depths on the North Carolina continental slope: B. filiformis off Cape Hatteras (588-930 m bathymetric depth) and B. major off Cape Lookout (850-1950 m depth). The sampling area, and particularly the 850 m station where B. filiformis is abundant (mean densities of 59-154 per m2), is believed to receive large inputs of organic material from various sources. This is consistent with the previously observed occurrence of large Bathysiphon species in regions of high food supply. Ten camera sled transects across the eastern U.S. continental slope between 32-degrees-N and 41-degrees-N emphasize the abundance of B. filiformis in the Cape Hatteras area compared with its rarity or absence elsewhere along the continental slope. Box cores, bottom photographs, and direct submersible observations indicate that B. filiformis tubes project above the sediment in an arcuate curve with only the lower 1 cm or so buried. Bathysiphon major adopts a similar orientation but has a greater proportion (50-80%) of the tube buried. The voluminous, dense, granular protoplasm of both species contains biogenic particles (including diatoms, in B. filiformis only), dinoflagellate cysts, fungal remains, pollen grains, tintinnid loricae, polychaete jaws and setae, benthic foraminiferal tests, and fish tooth fragments), suggesting that they feed mainly on material derived from the sediment surface. Submersible observations indicate that B. filiformis is patchily distributed at 100 m scales. Smaller scale dispersion patterns (analyzed from photographs) are generally random but with a tendency to be aggregated at lower densities and uniform at higher densities. A variety of metazoans and foraminifers live epifaunally on the outer surfaces of B. filiformis tubes. The most frequently occurring metazoans were larvae and juveniles of an unidentified gastropod and a tubiculous terebellid polychaete Nicolea sp. The most common epifaunal foraminifers were Tritaxis conica and Trochammina sp. Tubes of B. major, however, are virtually devoid of epifauna. Our results support the view that large, agglutinated rhizopod tests may influence the structure of deep-water benthic communities. However, in the case of Bathysiphon on the North Carolina continental slope, the effect appears limited to taxa directly associated with the foraminiferal tubes.

Grant, SB, Saphores JD, Feldman DL, Hamilton AJ, Fletcher TD, Cook PLM, Stewardson M, Sanders BF, Levin LA, Ambrose RF, Deletic A, Brown R, Jiang SC, Rosso D, Cooper WJ, Marusic I.  2012.  Taking the "Waste" Out of "Wastewater" for Human Water Security and Ecosystem Sustainability. Science. 337:681-686.   10.1126/science.1216852   AbstractWebsite

Humans create vast quantities of wastewater through inefficiencies and poor management of water systems. The wasting of water poses sustainability challenges, depletes energy reserves, and undermines human water security and ecosystem health. Here we review emerging approaches for reusing wastewater and minimizing its generation. These complementary options make the most of scarce freshwater resources, serve the varying water needs of both developed and developing countries, and confer a variety of environmental benefits. Their widespread adoption will require changing how freshwater is sourced, used, managed, and priced.

Grosholz, ED, Levin LA, Tyler C, Neira C.  2009.  Changes in community structure and ecosystem function following Spartina alterniflora invasion of Pacific estuaries. Human impacts on salt marshes : a global perspective. ( Silliman BR, Grosholz E, Bertness MD, Eds.).:23-40., Berkeley: University of California Press Abstract
Grupe, BM, Krach ML, Pasulka AL, Maloney JM, Levin LA, Frieder CA.  2015.  Methane seep ecosystem functions and services from a recently discovered southern California seep. Marine Ecology-an Evolutionary Perspective. 36:91-108.   10.1111/maec.12243   AbstractWebsite

The recent discovery of a methane seep with diverse microhabitats and abundant groundfish in the San Diego Trough (1020 m) off the coast of Del Mar, California raised questions about the role of seep ecosystem functions and services in relation to continental margins. We used multicorer and ROV grab samples and an ROV survey to characterize macrofaunal structure, diversity, and trophic patterns in soft sediments and authigenic carbonates; seep microhabitats and taxa observed; and the abundance and spatial patterns of fishery-relevant species. Biogenic microhabitats near the Del Mar Seep included microbially precipitated carbonate boulders, bacterial mats, vesicomyid clam beds, frenulate and ampharetid beds, vestimentiferan tubeworm clumps, and fields of Bathysiphon filiformis tubes. Macrofaunal abundance increased and mean faunal delta C-13 signatures decreased in multicorer samples nearer the seep, suggesting that chemosynthetic production enhanced animal densities outside the seep center. Polychaetes dominated sediments, and ampharetids became especially abundant near microbial mats, while gastropods, hydroids, and sponges dominated carbonate rocks. A wide range of stable isotopic signatures reflected the diversity of microhabitats, and methane-derived carbon was the most prevalent source of nutrition for several taxa, especially those associated with carbonates. Megafaunal species living near the seep included longspine thornyhead (Sebastolobus altivelis), Pacific dover sole (Microstomus pacificus), and lithodid crabs (Paralomis verrilli), which represent targets for demersal fisheries. Sebastolobus altivelis was especially abundant (6.5-8.2 fish.100 m(-2)) and appeared to aggregate near the most active seep microhabitats. The Del Mar Methane Seep, like many others along the world's continental margins, exhibits diverse ecosystem functions and enhances regional diversity. Seeps such as this one may also contribute ecosystem services if they provide habitat for fishery species, export production to support margin food webs, and serve as sinks for methane-derived carbon.

Guilini, K, Levin LA, Vanreusel A.  2012.  Cold seep and oxygen minimum zone associated sources of margin heterogeneity affect benthic assemblages, diversity and nutrition at the Cascadian margin (NE Pacific Ocean). Progress in Oceanography. 96:77-92.   10.1016/j.pocean.2011.10.003   AbstractWebsite

Hydrate Ridge (HR), located on the northeastern Pacific margin off Oregon, is characterized by the presence of outcropping hydrates and active methane seepage. Additionally, permanent low oxygen conditions overlay the benthic realm. This study evaluated the relative influence of both seepage and oxygen minima as sources of habitat heterogeneity and potential stress-inducing features on the bathyal metazoan benthos (primarily nematodes) at three different seep and non-seep HR locations, exposed to decreasing bottom-water oxygen concentrations with increasing water depth. The nematode seep communities at HR exhibited low diversity with dominance of only one or two genera (Daptonema and Metadesmolaimus), elevated average individual biomass and delta C-13 evidence for strong dependance on chemosynthesis-derived carbon, resembling deep-sea seeps worldwide. Although the HR seep habitats harbored a distinct nematode community like in other known seep communities, they differed from deep-sea seeps in well-oxygenated waters based on that they shared the dominant genera with the surrounding non-seep sediments overlain by oxygen-deficient bottom water. The homogenizing effect of the oxygen minimum zone on the seep nematode assemblages and surrounding sediments was constant with increasing water depth and concomitant greater oxygen-deficiency, resulting in a loss of habitat heterogeneity. (C) 2011 Elsevier Ltd. All rights reserved.