The JGOFS North Atlantic Bloom Experiment: An overview

The North Atlantic Bloom Experiment (NABE) of JGOFS presents a unique opportunity and challenge to the data management community because of the diversity and large size of biogeochemical data sets collected. NABE was a pilot study for JGOFS and has also served as a pilot study within the U.S. NODC for management and archiving of the data sets. Here I present an overview to some of the scientific results of NABE, which will be published as an Introduction to a special volume of NABE results in Deep-Sea Research later this year. An overview of NABE data management is given elsewhere in the present report. This is the first collection of papers from the Joint Global Ocean Flux Study (JGOFS). Formed as an international program in 1987, JGOFS has four principal elements: modelling and data management, multidisciplinary regional process studies, a global survey of biogeochemical properties and long-term time series observatories. In 1989-1990 JGOFS conducted a pilot process study of the spring phytoplankton bloom, the North Atlantic Bloom Experiment (NABE). JGOFS decided to conduct a large scale, internationally-coordinated pilot study in the North Atlantic because of its proximity to the founding nations of the project, the size and predictability of the bloom and its fundamental impact on ocean bio-geochemistry (Billett et al., 1983; Watson and Whitfield, 1985; Pfannkuche, 1992). In 1989, six research vessels from Canada, Germany, The Netherlands, the United Kingdom and the USA and over 200 scientists and students from more than a dozen nations participated in NABE. Some of their initial results are reported in this volume

Ocean Biogeochemical Fluxes - New Production And Export Of Organic-Matter From The Upper Ocean

Studies of ocean biogeochemical fluxes have been energized in this decade, by the urgency of our need to understand and predict the effects of continued CO2accumulation in the atmosphere, by the global perspectives offered by satellite views of ocean color and related physical fields (McClain et al. 1991; Yoder et al. 1992; Mitchell 1994), and by the successful implementation of the Joint Global Ocean Flux Study (JGOFS; Bowles and Livingston, 1993). In this review, I focus on oceanic new production, originally defined as the fraction of primary production supported by inputs of ‘new’ nitrogen from outside the euphotic zone. With a growing appreciation of the role of this fundamental biogeochemical flux in the global carbon cycle, it has become more common to refer interchangeably to new production so defined, and to the export of organic matter from the upper ocean (e.g.. Sarmiento and Siegenthaler 1992). New production, the driving process of the ocean carbon cycle, is responsible for maintaining over half the vertical gradient in total inorganic carbon. In this review I refer to nitrate‐based new production in the open sea, and not to new production supported by other N compounds as observed in the coastal zone. Eppley (1992) gives a personal view of the modern formulation of the concept of equivalence between new production and upper ocean export. This review is dedicated to the memory of John Martin, a friend, colleague, leader and teacher who contributed mightily to our field

Lessons for Social Workers: A Review of the Latino/a Undocumented Immigrant Experience

Undocumented Latino/a immigrants seeking social work services face additional challenges due to their immigration status, such as social isolation, trauma, a hostile political climate, and fear of deportation. The researcher of this systematic literature review sought to answer the research questions: “What factors do undocumented Latino/a immigrants identify as helpful when utilizing social work services?” and “What factors do undocumented Latino/a immigrants identify as hurtful or barriers when utilizing social work services?” A systematic review was conducted using the databases SOCIndex, PsycINFO, and Social Work Abstracts and variations of the search terms “Latino/a,” “immigrant,” and “social work services.” Articles that were peer-reviewed and directly incorporated the thoughts and opinions of immigrant clients were accepted for inclusion. In total, 14 articles met the inclusion and exclusion criteria for this literature review. The following themes emerged regarding factors that Latino/a immigrant clients identified as helpful or hurtful when accessing social work services: 1) accessibility of social work services, 2) language and culture, 3) discrimination and prejudice, and 4) information and resources. Future research implications included the need to increase the amount of studies that directly incorporate the voices of undocumented immigrants. Future research should also examine the effects of the larger political climate on social work practice with undocumented immigrants. Practice implications included the need for social workers to provide accessible, culturally responsive, and bilingual services to their undocumented Latino/a immigrant clients

Lessons for Social Workers: A Review of the Latino/a Undocumented Immigrant Experience

Undocumented Latino/a immigrants seeking social work services face additional challenges due to their immigration status, such as social isolation, trauma, a hostile political climate, and fear of deportation. The researcher of this systematic literature review sought to answer the research questions: “What factors do undocumented Latino/a immigrants identify as helpful when utilizing social work services?” and “What factors do undocumented Latino/a immigrants identify as hurtful or barriers when utilizing social work services?” A systematic review was conducted using the databases SOCIndex, PsycINFO, and Social Work Abstracts and variations of the search terms “Latino/a,” “immigrant,” and “social work services.” Articles that were peer-reviewed and directly incorporated the thoughts and opinions of immigrant clients were accepted for inclusion. In total, 14 articles met the inclusion and exclusion criteria for this literature review. The following themes emerged regarding factors that Latino/a immigrant clients identified as helpful or hurtful when accessing social work services: 1) accessibility of social work services, 2) language and culture, 3) discrimination and prejudice, and 4) information and resources. Future research implications included the need to increase the amount of studies that directly incorporate the voices of undocumented immigrants. Future research should also examine the effects of the larger political climate on social work practice with undocumented immigrants. Practice implications included the need for social workers to provide accessible, culturally responsive, and bilingual services to their undocumented Latino/a immigrant clients

The bacterial component of the oceanic euphotic zone

Bacteria in the open sea remote from land are sustained strictly on local sources of organic production which should make understanding their nutrition and growth regulation easier than in nearshore systems, estuaries and lakes. Until now, a paucity of data from geographically isolated oceanic sites prevented ready :interpretation. In the past decade investigation of bacterial properties in oceanic systems has increased rapidly, stimulated in part by large oceanographic programs like the Joint Global Ocean Flux Study. Here I review comprehensive investigations of bacterial biomass and production dynamics in the subarctic north Atlantic and north Pacific, oligotrophic gyres in both oceans, upwelling provinces in the equatorial Pacific and northwest Arabian Sea, and in the Ross Sea, Antarctica. Euphotic zone bacterial stocks are remarkably similar across all except the last regime, averaging about 1 g C m(-2). Production and growth rates vary more widely, suggesting independent regulation of biomass and production. The seasonal to annual mean ratio of bacterial to primary production is usually below 20%. (C) 1999 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved

Bacterioplankton growth responses to temperature and chlorophyll variations in estuaries measured by thymidine:leucine incorporation ratio

To identify the biochemical response of heterotrophic bacterioplankton to changing environmental conditions, seasonal and diel cycles of bacterial protein and DNA synthesis rates were estimated in temperate estuarine habitats from H-3-leucine (Leu) and H-3-thymidine (TdR) incorporation rates. Several short-term temperature manipulation experiments (5 to 35 degrees C) and 2 mesocosm experiments were performed to examine the effects of temperature and substrate supply on the ratio of Leu:TdR, respectively. The molar ratio of Leu to TdR varied about 5-fold (5.6 to 29.5) in the field and the values of the ratio were lower and more constant during high temperature (\u3e25 degrees C) and high chlorophyll a (\u3e8.0 mu g l(-1)) periods. In the temperature manipulation experiments, the Leu:TdR ratio decreased as temperature increased. In the mesocosm experiments, the Leu:TdR ratio was negatively correlated with chlorophyll a concentrations and bacterial specific growth rates. We propose that changes toward less favorable environmental conditions (e.g. reductions in temperature or substrate supply in temperate estuaries) might reduce bacterial protein and DNA synthesis rates simultaneously. However, the former process may be favored to maximize survival and this might lead to a higher Leu:TdR ratio. Conversely, when environmental conditions turn favorable, both processes could be enhanced and bacteria might optimize DNA duplication over protein metabolism to maximize reproduction, resulting in lower Leu:TdR ratios. Our results further indicate the complementariness of H-3-thymidine and H-3-leucine incorporation measurements for understanding processes controlling bacterial production since the ratio of these 2 tracer methods varied independently with temperature and substrate supply

Bacterioplankton distribution and production in the bathypelagic ocean: Directly coupled to particulate organic carbon export?

A recently published evaluation of bacterioplankton abundance and productivity in the bathypelagic North Pacific suggests that these properties are generally coupled with particulate organic carbon (POC) fluxes. In that analysis, bacterial biomass and productivity were several-fold greater in subarctic than subtropical waters, consistent with the basin-scale distribution of POC flux and suggestive of a sinking POC --\u3e DOC --\u3e bacteria transformation of the carbon. To test this hypothesis, we sought to determine whether the very strong spatial and temporal gradients in POC flux in the Arabian Sea would force similar deep-ocean gradients in bacterial variables. On both a within and between-cruise basis, there was variability in bacterial abundance and thymidine incorporation in the deep Arabian Sea, but correspondence was equivocal between these variables and several correlates to export: flux of biogenic carbon from the euphoric zone, state of the monsoon, and proximity to productive coastal upwelling zones. However, when annual mean bacterial abundance at 2,000 m was compared with annual POC flux at that depth, a strong correspondence emerged: high annual flux supported high bacterial abundance (such a correspondence was not found for bacterial productivity). This finding suggests that bathypelagic bacterial abundance responds to the long-term mean input of organic matter and less to episodic inputs. A comparative evaluation of the North Pacific revealed that although the bathypelagic bacteria there showed correspondence to deep POC flux, that variable alone would not account for the wide meridional variations in bacterial abundance that have been reported

Multiscale control of bacterial production by phytoplankton dynamics and sea ice along the western Antarctic Peninsula : a regional and decadal investigation

Author Posting. © The Author(s), 2012. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Journal of Marine Systems 98-99 (2012): 26-39, doi:10.1016/j.jmarsys.2012.03.003.We present results on phytoplankton and bacterial production and related hydrographic properties collected on nine annual summer cruises along the western Antarctic Peninsula. This region is strongly influenced by interannual variations in the duration and extent of sea ice cover, necessitating a decade-scale study. Our study area transitions from a nearshore region influenced by summer runoff from glaciers to an offshore, slope region dominated by the Antarctic Circumpolar Current. The summer bacterial assemblage is the product of seasonal warming and freshening following spring sea ice retreat and the plankton succession occurring in that evolving water mass. Bacterial production rates averaged 20 mgC m-2 d-1 and were a low (5%) fraction of the primary production (PP). There was significant variation in BP between regions and years, reflecting the variability in sea ice, Chlorophyll and PP. Leucine incorporation was significantly correlated (r2 ranging 0.2-0.7, p<0.001) with both chlorophyll and PP across depths, regions and years indicating strong phytoplankton-bacteria coupling. Relationships with temperature were variable, including positive, negative and insignificant relationships (r2 <0.2 for regressions with p<0.05). Bacterial production is regulated indirectly by variations in sea ice cover within regions and over years, setting the levels of phytoplankton biomass accumulation and PP rates; these in turn fuel BP, to which PP is coupled via direct release from phytoplankton or other less direct pathways.This research was supported by NSF Grants OPP-0217282 and 0823101 from the Antarctic Organisms and Ecosystems Program to HWD

Long-term studies of the marine ecosystem along the west Antarctic Peninsula

Author Posting. © The Author(s), 2008. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Deep Sea Research Part II: Topical Studies in Oceanography 55 (2008): 1945-1948, doi:10.1016/j.dsr2.2008.05.014.Articles in this volume focus on longer-term studies of the marine ecosystem of the continental shelf west of the Antarctic Peninsula, principally by the Palmer, Antarctica Long- Term Ecological Research project (Ross et al., 1996; Ducklow et al., 2007). There is a rich history of oceanographic and ecological research in the Bellingshausen Sea region and on the continental shelf dating back to the 19th and early 20th centuries (El-Sayed, 1996). The modern era of scientific research started with the British Discovery Investigations of 1925-37 (Hardy, 1967), and included classic studies of phytoplankton (Hart, 1934) and krill (Marr, 1962). Hart’s report presciently suggested primary producers could be limited by iron availability. El-Sayed (1996) dissects the subsequent history of oceanographic research up to the advent of the Southern Ocean GLOBEC (Hofmann et al., 2001; Hofmann et al., 2004) and JGOFS (Anderson and Smith Jr., 2001) programs. The period from the 1970’s to the mid-90’s was dominated by expeditionary and process-level studies of particular regions and processes extending over a few seasons to a few years at most. The Research on Antarctic Coastal Ecosystem Rates (RACER) Program (Huntley et al., 1991; Karl, 1991) is the outstanding example of this mode of research, having focused on determination of key rate processes as a new approach to understanding ecosystem dynamics (Karl et al., 1991a; Karl et al., 1991b). RACER was a direct predecessor and major influence on Palmer LTER, GLOBEC and JGOFS. What was lacking in Antarctic waters, as in most other regions and ocean provinces were sustained, long-term observations of a variety of ocean properties and rates, conducted in the context of hypothesis-driven, experimental science (Ducklow et al., 2008a). The creation of the US LTER Network in 1980 (Magnuson, 1990) made this possible.Observations reported in this volume were supported by NSF Grants OPP-90-11927 and OPP- 96-32763 to the University of California-Santa Barbara and OPP-02-17282 to the Virginia Institute of Marine Science

Ultrahigh bacterial production in a eutrophic subtropical Australian river : does viral lysis short-circuit the microbial loop?

Author Posting. © American Society of Limnology and Oceanography, 2011. This article is posted here by permission of American Society of Limnology and Oceanography for personal use, not for redistribution. The definitive version was published in Limnology and Oceanography 56 (2011): 1115-1129, doi:10.4319/lo.2011.56.3.1115.We studied trophic dynamics in a warm eutrophic subtropical river (Bremer River, Australia) to determine potential sources of dissolved organic carbon (DOC) and the fate of heterotrophic bacterial production. Sustained high rates of bacterial production suggested that the exogenous DOC was accessible (labile). Bacterial specific growth rates (0.2 h−1 to 1.8 h−1) were some of the highest measured for natural aquatic ecosystems, which is consistent with high respiration rates. Bacteria consumed 10 times more organic carbon than that supplied by the daily algal production, a result that implies that terrestrial sources of organic carbon were driving the high rates of bacterial production. Viruses (1011 L−1) were 10 times more abundant than bacteria; the viral to bacterial ratio ranged from 3.5 to 12 in the wet summer and 11 to 35 in the dry spring weather typical of eutrophic environments. Through a combination of high bacterial respiration and phage lysis, a continuous supply of terrestrial DOC was lost from the aquatic ecosystem in a CO2-vented bacterial–viral loop. Bacterial processing of DOC in subtropical rivers may be contributing disproportionately large amounts of CO2 to the global carbon cycle compared to temperate freshwater ecosystems.Thanks go to the Coastal Cooperative Research Centre and the Healthy Waterways Partnership for their funding