We do not know how the deep sea will be visited and sampled 50 years from now, but current pace and developments in data collection, management and analysis will undoubtedly improve our ability to investigate the deep sea. In imagining the future landscape of deep-sea research we might dream of exciting technological advances, but stark reality tells us that financial limitations will continue to impact on our research endeavours. Researchers need to deliver high-quality science in the most cost-effective way, and leave a legacy of archived data for future generations. We may see greater data collection from ships of opportunity, and certainly from autonomous vehicles, and seabed observatories. The need for baseline data remains a challenge, and visual data will become more important. Data collection and analyses need to be multidisciplinary and collaborative, using geospatial methods to identify spatial and temporal change. The need for trained taxonomists to identify deep-sea organisms will remain, although genetic techniques will greatly assist in this important task. Information exchange underpins the world in which we live, and an increasingly connected and more informed public will place even greater demands on scientists to anticipate the likely human impacts in the deep sea, and inform deep-sea management, walking a tightrope between conservation and exploitation.

Seamounts shape the topography of all ocean basins and can be hotspots of biological activity in the deep sea. The Census of Marine Life on Seamounts (CenSeam) was a field program that examined seamounts as part of the global Census of Marine Life (CoML) initiative from 2005 to 2010. CenSeam progressed seamount science by collating historical data, collecting new data, undertaking regional and global analyses of seamount biodiversity, mapping species and habitat distributions, challenging established paradigms of seamount ecology, developing new hypotheses, and documenting the impacts of human activities on seamounts. However, because of the large number of seamounts globally, much about the structure, function and connectivity of seamount ecosystems remains unexplored and unknown. Continual, and potentially increasing, threats to seamount resources from fishing and seabed mining are creating a pressing demand for research to inform conservation and management strategies. To meet this need, intensive science effort in the following areas will be needed: 1) Improved physical and biological data; of particular importance is information on seamount location, physical characteristics (e.g. habitat heterogeneity and complexity), more complete and intensive biodiversity inventories, and increased understanding of seamount connectivity and faunal dispersal; 2) New human impact data; these shall encompass better studies on the effects of human activities on seamount ecosystems, as well as monitoring long-term changes in seamount assemblages following impacts (e.g. recovery); 3) Global data repositories; there is a pressing need for more comprehensive fisheries catch and effort data, especially on the high seas, and compilation or maintenance of geological and biodiversity databases that underpin regional and global analyses; 4) Application of support tools in a data-poor environment; conservation and management will have to increasingly rely on predictive modelling techniques, critical evaluation of environmental surrogates as faunal “proxies”, and ecological risk assessment.

In 2005 the Census of Marine Life launched ''A Global Census of Marine Life on Seamounts'' (CenSeam), an international science project to increase our knowledge of the ecology of seamounts.Specifically, the mission of CenSeam was to determine the role of seamounts in the biogeography, biodiversity, productivity, and evolution of marine organisms, and to evaluate the effects of human impacts on seamounts.Here we overview the history, goals, activities and programmatic outcomes of CenSeam, with recommendations for improving similar programs in the future.Effective components of the project included mini-grants of generally less than US$10,000 to fund proposal development or difficult-to-fund research, or to expand the scope of an expedition; travel funds for data analysis working groups to meet, several times if needed, to address a targeted research question; advanced training workshops for both young researchers and established scientists; staff support for organizing books, special issues in journals, and review papers; and advising conservation and management initiatives on seamount science.From a programmatic perspective, the lessons learned include the importance of: having the science community develop and endorse the key programmatic and scientific goals; in-person meetings and workshops to foster new collaborations; promoting open data sharing; funding salary time for critical work; and establishing and actively managing open communication mechanisms to allow scientists to develop a consensus opinion on science topics, which could then be conveyed to conservation and management organizations.

Despite a relatively short history, the field of seamount ecology is rife with ecological paradigms, many of which have already become cemented in the scientific literature and in the minds of advocates for seamount protection. Together, these paradigms have created a widely held view of seamounts as unique environments, hotspots of biodiversity and endemicity, and fragile ecosystems of exceptional ecological worth. However, closer examination reveals significant gaps in our knowledge, thereby calling the accuracy of some of these paradigms into question. Here, we review the evolution of the major paradigms in seamount ecology, assess their status against the weight of existing evidence to date, identify emerging paradigms, and suggest future research directions. We find the assertions that seamount communities are vulnerable to fishing, and that these communities have high sensitivity and low resilience to bottom trawling disturbance are well supported by existing data. We find plausible evidence that seamounts are stepping stones for dispersal, oases of abundance and biomass, and hotspots of species richness. Nonetheless, the poor sampling coverage of these discrete but globally distributed environments prevents us from accepting these ideas as paradigms. Also plausible, but requiring further investigation, are the emerging paradigms that seamount communities are structurally distinct, that populations of invertebrates on seamounts are the source of propagules for nearby slope sinks, and that seamounts have acted and can act as biological refugia from large-scale catastrophic environmental events. In contrast, the generalizations that seamounts are island habitats with highly endemic faunas that comprise unique communities distinct in species composition from other deep-sea habitats, and that they have high production supported by localized bottom-up forcing, are not supported by the weight of existing evidence.

Because the nature, tempo and trajectories of biological changes that follow the cessation of trawling are unknown for seamounts, it is unclear whether closing them to trawling will lead to a recovery of the fauna and, if so, over what time scales. This paper reports on a 'test of recovery' from repeated towed camera surveys on three seamounts off New Zealand in 2001 and 2006 (5 years apart) and three off Australia in 1997 and 2006 (10 years apart). In each region, seamounts where trawling had ceased were compared to adjacent seamounts where trawling was still active, and to seamounts that had never been trawled. If recovery signals existed, the likelihood of detecting them was high because the seamounts were relatively small and topographically simple, and because quantitative survey methods were employed. Multivariate patterns showed no change in the megafaunal assemblage consistent with recovery over a 5-10 year timeframe on seamounts where trawling had ceased. Results based on the number of species and diversity were equivocal, with some cases of increase and decrease on seamounts where trawling had ceased. A few individual taxa were found at significantly higher abundance in the later surveys where trawling had occurred. We suggest this may have resulted from their resistance to the direct impacts of trawling (two chrysogorgid corals and solitary scleractinians), or from protection in natural refuges inaccessible to trawls (unstalked crinoids, two chrysogorgid corals, gorgonians, and urchins). Alternatively, these taxa may represent the earliest stages of seamount recolonisation. They have potential to be dominant for long periods because the pre-trawling composition of benthic assemblages on seamounts includes taxa that grow slowly and/or have an association with 'thickets' of a single keystone stony coral (Solenosmilia variabilis) that has generated biogenic habitat over millennia. Resilience of seamount ecosystems dominated by corals is low compared to most other marine systems subject to disturbance by bottom trawling because there are no alternative habitats of the same value for supporting associated species, and because trawling typically removes coral habitat from large areas of individual seamounts. Management to conserve seamount ecosystems needs to account for changing oceanographic conditions (ocean acidification), as well as the direct impacts of human activities such as bottom trawling. Networks of spatial closures that include intact habitats over a range of depths, especially < 1500 m, and on clusters and isolated seamounts, may be effective by maintaining the resilience of seamount benthic communities.

Conventional wisdom suggests that seamounts harbour high levels of biodiversity and endemism, play important roles in marine biogeography, are hotspots of biological carbon processing, and support substantial fisheries. However, since fewer than 300 seamounts have been thoroughly sampled, these generalizations remain largely untested. This has provided the motivation for a number of seamount-focused research projects in recent years, including CenSeam, a field project within the Census of Marine Life. This issue presents some of the research output facilitated by CenSeam. Here we summarize the main findings and provide a precis of future research directions highlighted by contributors to the issue. Recent studies show that seamounts can have comparable levels of benthic diversity and endemism to continental margins, but their communities also include a distinct composition of species that can attain higher biomass. Reported geographic differentiation among seamount communities suggests limited larval dispersal, local speciation, geographic isolation, or a combination of these processes. Genetic studies contained in the issue address these themes explicitly, documenting complex patterns of connectivity that depend on spatial scale and life history characteristics. Globally, seamount ecosystems are also under pressure from bottom-contact fishing and ocean acidification. Contributions detailing the footprint of trawling and a risk assessment confirm what has long been suspected: seamount ecosystems are highly vulnerable to disturbance by bottom trawling and recovery from fishing impacts is a lengthy process, likely requiring decades at a minimum. A predicted shallowing of the aragonite saturation horizon caused by ocean acidification is predicted to place deep-water corals at risk, but seamounts may yet provide a spatial/chemical refuge from these impacts. The issue concludes with a 'myth-buster' synthesis that updates the status of the various seamount ecological paradigms.

Seamounts have often been viewed as specialized habitats that support unique communities; this notion has given rise to several hypotheses about how seamount ecosystems are structured. One, the 'seamount oasis hypothesis', predicts that invertebrates are more abundant, speciose and attain higher standing stocks on seamounts compared to other deep-sea habitats. Because this hypothesis has remained untested for biomass, we ask two questions: (i) Do seamounts support a higher benthic biomass than nearby slopes at corresponding depths? (ii) If they do, which particular taxa and trophic groups drive observed difference in biomass? Analysis of more than 5000 sea-floor images reveals that the mean biomass of epibenthic megafauna on 20 southwest Pacific seamounts was nearly four times greater than on the adjacent continental slope at comparable depths. This difference is largely attributable to the scleractinian coral Solenosmilia variabilis, whose mean biomass was 29 times higher on seamounts. In terms of trophic guilds, filter-feeders and filter-feeders/predators made up a significantly greater proportion of biomass on seamounts, whereas deposit feeders and those with mixed feeding modes dominated at slope habitats. Notwithstanding support for the seamount oasis hypothesis provided by this study, the hypothesis needs to be critically tested for seamounts in less productive regions, for seamounts with a greater proportion of soft substratum, and in other parts of the oceans where scleractinian corals are not prevalent. In this context, testing of seamount paradigms should be embedded in a broader ecological context that includes other margin habitats (e.g. canyons) and community metrics (e.g. diversity and body size).

Chapter 7 Life on Seamounts Mireille Consalvey, Mireille Consalvey National Institute of Water and Atmospheric Research, P.B. 14-901, Wellington, New ZealandSearch for more papers by this authorMalcolm R. Clark, Malcolm R. Clark National Institute of Water and Atmospheric Research, P.B. 14-901, Wellington, New ZealandSearch for more papers by this authorAshley A. Rowden, Ashley A. Rowden National Institute of Water and Atmospheric Research, P.B. 14-901, Wellington, New ZealandSearch for more papers by this authorKaren I. Stocks, Karen I. Stocks San Diego Supercomputer Center, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093, USASearch for more papers by this author Mireille Consalvey, Mireille Consalvey National Institute of Water and Atmospheric Research, P.B. 14-901, Wellington, New ZealandSearch for more papers by this authorMalcolm R. Clark, Malcolm R. Clark National Institute of Water and Atmospheric Research, P.B. 14-901, Wellington, New ZealandSearch for more papers by this authorAshley A. Rowden, Ashley A. Rowden National Institute of Water and Atmospheric Research, P.B. 14-901, Wellington, New ZealandSearch for more papers by this authorKaren I. Stocks, Karen I. Stocks San Diego Supercomputer Center, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093, USASearch for more papers by this author Book Editor(s):Alasdair D. McIntyre, Alasdair D. McIntyre The University of Aberdeen, Scotland, UKSearch for more papers by this author First published: 08 October 2010 https://doi.org/10.1002/9781444325508.ch7Citations: 14 AboutPDFPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShareShare a linkShare onFacebookTwitterLinked InRedditWechat Summary This chapter contains sections titled: Introduction: A History of Seamount Research A Global Census of Marine Life on Seamounts (CenSeam) What Factors Drive Community Composition and Diversity on Seamounts? What are the Impacts of Human Activities on Seamount Community Structure and Function? Knowledge Transfer to Stakeholders Moving Beyond 2010: Emerging Issues Moving Forward: The Next Decade of Seamount Research Acknowledgments References Citing Literature Life in the World's Oceans: Diversity, Distribution, and Abundance RelatedInformation

The “Graveyard seamounts” comprise a complex of 28 small volcanic edifices covering about 140 km2 on the northern flank of the Chatham Rise, an oceanic plateau that extends several hundred kilometers east of New Zealand. The features are associated with widely distributed Late Cenozoic volcanism that created a number of clusters of small intraplate volcanoes in the area. They have various volcanic forms, including cones, summit craters, and lateral dike ridges. Typically, each seamount is between 100 and 400 m high, rising from basal water depths of 1050–1200 m to summit depths of 750–1000 m. Bottom-current flows of 10–20 cm s-1 produce basal scour moats at all the seamounts.

In this review of seamount ecology, we address a number of key scientific issues concerning the structure and function of benthic communities, human impacts, and seamount management and conservation. We consider whether community composition and diversity differ between seamounts and continental slopes, how important dispersal capabilities are in seamount connectivity, what environmental factors drive species composition and diversity, whether seamounts are centers of enhanced biological productivity, and whether they have unique trophic architecture. We discuss how vulnerable seamount communities are to fishing and mining, and how we can balance exploitation of resources and conservation of habitat. Despite considerable advances in recent years, there remain many questions about seamount ecosystems that need closer integration of molecular, oceanographic, and ecological research.

Biological communities on seamounts are widely regarded as being distinct from those in other offshore habitats, but it is unclear what factors drive any differences. We used invertebrate and algal data from the extensive REVIZEE benthic surveys from the continental margin and seamounts in the Southwest Atlantic Ocean off Eastern Brazil to investigate environmental predictors of seamount assemblage composition. We found that seamount summit samples were significantly different from those of the continental shelf for both invertebrates and algae. Invertebrate samples from the shelf showed more spatial variability than those from seamounts, congruent with the increased variability in both sampled sea-floor habitats and oceanographic conditions recorded along the continental margin. The most important environmental predictors of assemblage composition across all habitats were distance from shore, temperature, dissolved oxygen and particulate organic carbon for invertebrates, and distance from shore, nitrate and phosphate concentrations for algae. Only distance from shore for invertebrates, and distance from shore, nitrate and phosphate concentrations for algae were consistently emphasised in analyses restricted to seamount and island samples. We found no support for the hypothesis that seamount assemblages in this region become less species rich with distance from the continental margin. However, algal samples did form a serial gradient of compositional turnover with distance from shore. In summary, the seamounts shared the same species pool as nearby continental margins but samples contained a different, equally rich, assemblage of species.

Aim  Globally, species distribution patterns in the deep sea are poorly resolved, with spatial coverage being sparse for most taxa and true absence data missing. Increasing human impacts on deep‐sea ecosystems mean that reaching a better understanding of such patterns is becoming more urgent. Cold‐water stony corals (Order Scleractinia) form structurally complex habitats (dense thickets or reefs) that can support a diversity of other associated fauna. Despite their widely accepted ecological importance, records of scleractinian corals on seamounts are patchy and simply not available for most of the global ocean. The objective of this paper is to model the global distribution of suitable habitat for stony corals on seamounts.

Massive coral species play a key role in coral reef ecosystems, adding significantly to physical integrity, long term stability and reef biodiversity. This study coupled the assessment of the distribution and abundance of 4 dominant massive coral species, Diploastrea heliopora, Favia speciosa, F matthaii and Porites lutea, with investigations into species-specific photoacclimatory responses within the Wakatobi Marine National Park of southeast Sulawesi, Indonesia, to determine the potential of photoacclimation to be a driver of biological success. For this, rapid light curves using pulse amplitude modulated (PAM) chlorophyll a fluorescence techniques were employed with additional manipulations to circumvent differences of light quality and absorption between species and across environmental gradients. P. lutea was examined over a range of depths and sites to determine patterns of photoacclimation, and all 4 species were assessed at a single depth between sites for which long-term data for coral community structure and growth existed. Light availability was more highly constrained with depth than between sites; consequently, photoacclimation patterns for P. lutea appeared greater with depth than across environmental gradients. All 4 species were found to differentially modify the extent of non-photochemical quenching to maintain a constant photochemical operating efficiency (qP). Therefore, our results suggest that these massive corals photoacclimate to ensure a constant light-dependent rate of reduction of the plastoquinone pool across growth environments.

Microphytobenthos (MPB) on intertidal mudflats is a major component of primary pro- ducers in some estuarine ecosystems. To sustain photosynthesis, MPB migrate through the upper sed- iment layer and form transient biofilms during emersion periods, and thus may be exposed to high irradiance and ultraviolet radiation (UV-R), possibly resulting in photodamage to the photosynthetic apparatus. In contrast, downard migration could allow cells to optimize position in the photic zone, avoiding photoinhibitory light levels. Engineered biofilms with inhibited migratory capacity were used to distinguish between possible strategies (photoacclimation or migration) evolved by MPB to cope with photoinhibitory irradiances, when a series of UV filters with different cut-off wavelengths was used to estimate the respective contribution of visible light and UV-R. Engineered biofilms with full migratory capacity maintained a high relative electron transport rate (rETR), in contrast to engi- neered non-migratory biofilms, which showed a decrease in rETR under high irradiance, with a greater decrease under UV-B radiation. Migration thus appeared to be the principal short-term mechanism allowing MPB to avoid or minimize UV-R and high PAR photodamage in situ. Neverthe- less, physiological acclimation processes to different light levels ('light-shade' patterns) seem to occur in the long term, and probably superimpose on migratory capacity, making light history an important component of MPB photoacclimation strategies.

For the first time we have investigated the natural ecosystem engineering capacity of stromatolitic microbial assemblages. Stromatolites are laminated sedimentary structures formed by microbial activity and are considered to have dominated the shallows of the Precambrian oceans. Their fossilised remains are the most ancient unambiguous record of early life on earth. Stromatolites can therefore be considered as the first recognisable ecosystems on the planet. However, while many discussions have taken place over their structure and form, we have very little information on their functional ecology and how such assemblages persisted despite strong eternal forcing from wind and waves. The capture and binding of sediment is clearly a critical feature for the formation and persistence of stromatolite assemblages. Here, we investigated the ecosystem engineering capacity of stromatolitic microbial assemblages with respect to their ability to stabilise sediment using material from one of the few remaining living stromatolite systems (Highborne Cay, Bahamas). It was shown that the most effective assemblages could produce a rapid (12-24 h) and significant increase in sediment stability that continued in a linear fashion over the period of the experimentation (228 h). Importantly, it was also found that light was required for the assemblages to produce this stabilisation effect and that removal of assemblage into darkness could lead to a partial reversal of the stabilisation. This was attributed to the breakdown of extracellular polymeric substances under anaerobic conditions. These data were supported by microelectrode profiling of oxygen and calcium. The structure of the assemblages as they formed was visualised by low-temperature scanning electron microscopy and confocal laser microscopy. These results have implications for the understanding of early stromatolite development and highlight the potential importance of the evolution of photosynthesis in the mat forming process. The evolution of photosynthesis may have provided an important advance for the niche construction activity of microbial systems and the formation and persistence of the stromatolites which came to dominate shallow coastal environments for 80% of the biotic history of the earth.