Ronald S. Kaufmann

Climate, carbon cycling, and deep-ocean ecosystems

Climate variation affects surface ocean processes and the production of organic carbon, which ultimately comprises the primary food supply to the deep-sea ecosystems that occupy ≈60% of the Earths surface. Warming trends in atmospheric and upper ocean temperatures, attributed to anthropogenic influence, have occurred over the past four decades. Changes in upper ocean temperature influence stratification and can affect the availability of nutrients for phytoplankton production. Global warming has been predicted to intensify stratification and reduce vertical mixing. Research also suggests that such reduced mixing will enhance variability in primary production and carbon export flux to the deep sea. The dependence of deep-sea communities on surface water production has raised important questions about how climate change will affect carbon cycling and deep-ocean ecosystem function. Recently, unprecedented time-series studies conducted over the past two decades in the North Pacific and the North Atlantic at >4,000-m depth have revealed unexpectedly large changes in deep-ocean ecosystems significantly correlated to climate-driven changes in the surface ocean that can impact the global carbon cycle. Climate-driven variation affects oceanic communities from surface waters to the much-overlooked deep sea and will have impacts on the global carbon cycle. Data from these two widely separated areas of the deep ocean provide compelling evidence that changes in climate can readily influence deep-sea processes. However, the limited geographic coverage of these existing time-series studies stresses the importance of developing a more global effort to monitor deep-sea ecosystems under modern conditions of rapidly changing climate.

Spatial and temporal variation in the abundance, distribution and population structure of epibenthic megafauna in Port Foster, Deception Island

Abundance and spatial distribution of epibenthic megafauna were examined at Port Foster, Deception Island, five times between March 1999 and November 2000. Camera sled surveys and bottom trawls were used to identify and collect specimens, and camera sled photographs also were used to determine abundances and spatial distributions for each species. The ophiuroid Ophionotus victoriae, the regular echinoid Sterechinus neumayeri, and one or more species of Porifera were the most abundant taxa during this sampling period. Abundances of O. victoriae varied throughout the annual cycle, peaking in June 2000, and were correlated positively with sedimentation rates. In contrast, abundances of S. neumayeri were consistent throughout the sampling period, except for a peak in June 2000, during austral winter. Peak abundances for both species coincided with a large number of small individuals, indicating apparent recruitment events for O. victoriae and S. neumayeri during this time period. Poriferans, as a group, had statistically similar abundances during each sampling period. Low-abundance species tended to be aggregated on both small and large spatial scales, their distributions probably influenced by reproductive method, gregarious settlement, and food availability. The spatial distribution of S. neumayeri in June 2000 and O. victoriae was random across multiple spatial scales, perhaps in response to food availability and broad environmental tolerances, respectively.

Seasonal variation in biochemical indicators of physiological status in Euphausia superba from Port Foster, Deception Island, Antarctica

Seasonal changes in biochemical indicators of physiological status were analyzed in abdominal muscle of the Antarctic krill, Euphausia superba, collectedfrom Port Foster, Deception Island , an active volcano locatedin the ShetlandIslandchain west of the Antarctic Peninsula. Krill were collectedwith a 10 m 2 MOCNESS trawl during four cruises (November 1999, February, May, November 2000). RNA:DNA mirroredthe chlorophyll a concentration, with the highest values found during seasons of abundant phytoplankton. Activities of the glycolytic enzyme lactate dehydrogenase (LDH) and the mitochondrial enzyme citrate synthase (CS) were significantly higher in male krill when comparedto females of similar size, indicating that their burst andaerobic swimming performance may be higher than females throughout the year. RNA:DNA ratio andenzyme activities were highly elevatedin summer as comparedto the earliest spring sampling period. Krill showed significant seasonal changes in LDH activity, with lowest values in spring andhighest values in summer (females) or autumn (males). Krill showedsignificant seasonal changes in CS activity with highest values in summer. Protein and% water variedsignificantly among seasons for both males and females. Lower CS activity and RNA:DNA ratio suggest krill exhibit reduced metabolism during the winter when phytoplankton production is reduced, perhaps enhancing survival. Lower enzyme activities in female krill in early spring suggest they may achieve greater metabolic suppression during overwintering. r 2003 Elsevier Ltd. All rights reserved.

Temporal patterns in the distribution, biomass and community structure of macrozooplankton and micronekton within Port Foster, Deception Island, Antarctica

The pelagic community within the flooded caldera of Deception Island, Antarctica, was sampled with a 10-m 2

Ecosystem studies at Deception Island, Antarctica: an overview

The Southern Ocean represents one of the most extreme marine environments on Earth, characterized by low temperature throughout the water column and extensive seasonal ice cover resulting in high temporal variability in primary production (Smith and Nelson, 1986; Arrigo et al., 1997). This fluctuating production of organic matter heavily impacts the marine ecosystem. Ship-based measurements and observations during all seasons of the year have provided a description of ecosystems encompassing surface to benthic communities (Ainley et al., 1991; Lancraft et al., 1991; Siegel et al., 1992; Hopkins et al., 1993; Grebmeier and Barry, 1991; Knox, 1994). However, seasonal ice cover has impeded year-round studies of how these ecosystems function, especially under such extreme conditions. Long time-series studies are critical in understanding processes affecting marine ecosystems on seasonal and annual time scales (Austen et al., 1991; Brodeur and Ware, 1992; Deuser et al., 1995). Such studies are especially important in geographic regions, such as the Southern Ocean, that experience high annual variability in physically and/or chemically mediated processes (e.g., Franklin, 1989). In situ long-term monitoring has been employed successfully in the Southern Ocean to document extreme temporal variability in the sinking of particulate matter (e.g., Collier et al., 2000). Much of this variability appears related to seasonal ice cover and the production of organic matter in the surface waters of both open-ocean (Wefer et al., 1988; Fischer et al., 1988; Wefer and Fischer, 1991) and shelf (Fukuchi et al., 1988; Dunbar et al., 1989, 1998; DeMaster et al., 1992) environments. A study of the marine ecosystem associated with Port Foster, Deception Island, in the South Shetland Islands, Antarctica (Fig. 1), was undertaken with the intent of utilizing a long time-series approach to monitoring the unique marine communities in this polar environment throughout an annual cycle. Such long time-series studies are essential to understanding the impact of global warming in these highly temperature-sensitive environments. Evidence is now accumulating that the Antarctic Peninsula area has warmed over the past half century by as much as 2.5 C along the western coastline (Vaughan and Doake, 1996; Vaughan et al., 2001). Warming in the Antarctic Peninsula region, including the South Shetland and South Orkney Islands, has been related to changes in marine populations ranging from predators such as penguins (Fraser et al., 1992) seals and albatross to prey such as krill (Reid and Croxall, 2001). Port Foster, the sunken, seawater flooded caldera of Deception Island, was chosen for our studies because of its proximity to Antarctic stations located within the South Shetland Islands and along the northwestern side of the Antarctic Peninsula (Fig. 1) where long time-series climate and marine community data have been collected for decades. Deception Island is also the site of several scientific stations occupied by British, Chilean, Argentine and Spanish contingents since the mid-1930s. This island also afforded a unique opportunity to work in a semi-enclosed environment that could be monitored effectively with long-term instrumentation while being free from ARTICLE IN PRESS

Spatial and temporal variability of mesozooplankton and tintinnid ciliates in a seasonally hypersaline estuary

The zooplankton community of Mission Bay, San Diego, California, was monitored over two years, to study spatial and temporal patterns and the response of zooplankton species composition to environmental variation. Data were collected every two weeks from six stations and included hydrographic parameters, dissolved nutrient concentrations, and phytoplankton and zooplankton species composition. Hydrography varied seasonally, along a spatial gradient from the mouth to the back of the bay, and between the two years around the influence of rainfall. Spatially, Mission Bay could be divided into three regions during this study based on hydrography and zooplankton species composition. Zooplankton species composition followed a predictable seasonal progression, with different groups of species being characteristic to particular times of the year. Variability in zooplankton species composition was also evident between years, as certain species were more common in one or the other year of the study. Spatial patterns were more consistent than temporal ones, and related to distance from the mouth of the bay during much of the year and distance from freshwater inlets during the relatively short rainy season. Multivariate analysis revealed that variation in zooplankton species composition was best related to measured abiotic factors (temperature, salinity, rainfall, and tidal velocity).

Spatial characterization of the meltwater field from icebergs in the Weddell Sea

We describe the results from a spatial cyberinfrastructure developed to characterize the meltwater field around individual icebergs and integrate the results with regional- and global-scale data. During the course of the cyberinfrastructure development, it became clear that we were also building an integrated sampling planning capability across multidisciplinary teams that provided greater agility in allocating expedition resources resulting in new scientific insights. The cyberinfrastructure-enabled method is a complement to the conventional methods of hydrographic sampling in which the ship provides a static platform on a station-by-station basis. We adapted a sea-floor mapping method to more rapidly characterize the sea surface geophysically and biologically. By jointly analyzing the multisource, continuously sampled biological, chemical, and physical parameters, using Global Positioning System time as the data fusion key, this surface-mapping method enables us to examine the relationship between the meltwater field of the iceberg to the larger-scale marine ecosystem of the Southern Ocean. Through geospatial data fusion, we are able to combine very fine-scale maps of dynamic processes with more synoptic but lower-resolution data from satellite systems. Our results illustrate the importance of spatial cyberinfrastructure in the overall scientific enterprise and identify key interfaces and sources of error that require improved controls for the development of future Earth observing systems as we move into an era of peta- and exascale, data-intensive computing.

Microbiome Composition and Diversity of the Ice-Dwelling Sea Anemone, Edwardsiella andrillae.

Edwardsiella andrillae is a sea anemone (Cnidaria: Anthozoa: Actiniaria) only known to live embedded in the ice at the seawater interface on the underside of the Ross Ice Shelf, Antarctica. Although the anatomy and morphological characteristics of E. andrillae have been described, the adaptations of this species to the under-ice ecosystem have yet to be examined. One feature that may be important to the physiology and ecology of E. andrillae is its microbiome, which may play a role in health and survival, as has been deduced in other metazoans, including anthozoans. Here we describe the microbiome of five specimens of E. andrillae, compare the diversity we recovered to that known for temperate anemones and another Antarctic cnidarian, and consider the phylogenetic and functional implications of microbial diversity for these animals. The E. andrillae microbiome was relatively low in diversity, with seven phyla detected, yet included substantial phylogenetic novelty. Among the five anemones investigated, the distribution of microbial taxa varied; this trait appears to be shared by many anthozoans. Most importantly, specimens either appeared to be dominated by Proteobacteria-affiliated members or by deeply branching Tenericute sequences. There were few closely related sequence types that were common to temperate and Antarctic sea anemone microbiomes, the exception being an Acinetobacter-related representative. Similar observations were made between microbes associated with E. andrillae and an Antarctic soft coral; however, there were several closely-related, low abundance Gammaproteobacteria in both Antarctic microbiomes, particularly from the soft coral, that are also commonly detected in Southern Ocean seawater. Although this preliminary study leaves open many questions concerning microbiome diversity and its role in host ecology, we identify major lineages of microbes (e.g., diverse deep-branching Alphaproteobacteria, Epsilonproteobacteria, and divergent Tenericutes affiliates) that may play critical roles, and we highlight the current understanding and the need for future studies of sea anemone-microbiome relationships.

Pathology of Ocular Lesions Associated with Gas Supersaturation in White Seabass

Cultured juvenile white seabass Atractoscion nobilis (WSB) can suffer from intraocular emphysemas and exophthalmia in the hatchery environment. To identify the cause, two size-groups of WSB were exposed to five gas saturation levels, ranging from 98% to 122% total gas pressure (TGP), over a 96-h exposure period in 18 degrees C and 23 degrees C seawater. Histological examination revealed that the gross and subgross lesions associated with gas supersaturation included corneal and orbital emphysema, along with subretinal, optic nerve, and iridial hemorrhage. Corneal emphysema was the most prominent gross lesion, with the severity and prevalence increasing between size-groups and water temperatures as TGP increased. Following the same pattern was orbital emphysema, which affected more than 93% of the fish examined and caused hemorrhage in the subretinal space, around the optic nerve, in the iris, or a combination thereof. Iridial hemorrhage occurred in 91% of the fish examined and decreased significantly with fish size. The prevalence and severity of hemorrhage in the subretinal space increased significantly with TGP and fish size but not with temperature. Optic nerve hemorrhage was absent in small fish exposed at 18 degrees C but increased significantly with temperature and fish size. The reverse was true for the large fish.