Search

A primary focus of the US Global Ocean Ecosystem Dynamics (GLOBEC) program was to identify the mechanisms of ecosystem response to large-scale climate forcing under the assumption that bottom-up forcing controls a large fraction of marine ecosystem variability. At the beginning of GLOBEC, the prevailing bottom-up forcing hypothesis was that climate-induced changes in vertical transport modulated nutrient supply and surface primary productivity, which in turn affected the lower trophic levels (e.g., zooplankton) and higher trophic levels (e.g., fish) through the trophic cascade. Although upwelling dynamics were confirmed to be an important driver of ecosystem variability in GLOBEC studies, the use of eddy-resolving regional-scale ocean circulation models combined with field observations revealed that horizontal advection is an equally important driver of marine ecosystem variability. Through a synthesis of studies from the four US GLOBEC regions (Gulf of Alaska, Northern California Current, Northwest Atlantic, and Southern Ocean), a new horizontal-advection bottom-up forcing paradigm emerges in which large-scale climate forcing drives regional changes in alongshore and cross-shelf ocean transport that directly impact ecosystem functions (e.g., productivity, species composition, spatial connectivity). The horizontal advection bottom-up forcing paradigm expands the mechanistic pathways through which climate variability and climate change impact the marine ecosystem. In particular, these results highlight the need for future studies to resolve and understand the role of mesoscale and submesoscale transport processes and their relationship to climate.

Management of living marine resources is undergoing a profound transition toward a more holistic, ecosystem-based paradigm. The interplay of climate and environmental forcing, ecosystem structure and function, and human influences and requirements shape the dynamics of these systems in complex ways. The US Global Ocean Ecosystem Dynamics (GLOBEC) program was designed to unravel the elements of this complexity and to forge the tools needed to explore the scope for predictability of ecosystem change in a rapidly changing ocean. As a basic science program, US GLOBEC established new standards in ecological monitoring, technological development, and coupled bio-physical modeling of marine systems. Its legacy goes beyond these fundamental achievements, however, through the realized and potential importance of the GLOBEC approach and findings in resource management. Development of the US GLOBEC program considerably predated the formal adoption of strategies for ecosystem-based management of coastal and marine systems in the United States under the aegis of the National Ocean Policy. The GLOBEC strategy and its resulting products and tools have nonetheless proven extremely valuable in moving toward the goal of operational marine ecosystem-based management. The GLOBEC selection of target species of direct relevance to management (including economically important species and those with special conservation status) underscored the recognized need to provide results of the highest scientific caliber while also meeting broader societal needs and objectives for sustainable resource management. Here, we trace some of the current applications of GLOBEC science in resource management (including the extension of single species management strategies to incorporate climate forcing and the use of broader ecosystem models) and point to its potential to further shape the evolution of marine ecosystem-based management.

Lower trophic level (LTL) ocean ecosystem models are important tools for understanding ocean biogeochemical variability and its role in Earth's climate system. These models are often replete with parameters that cannot be well constrained by the sparse observational data available. LTL ocean ecosystem model parameter estimation is examined from a probabilistic perspective, using a Bayesian hierarchical model (BHM), in the coastal Gulf of Alaska (CGOA) domain that benefits from ocean station observations obtained in repeated US GLOBEC cruises. Data entering the BHM include daily average SeaWiFS satellite estimates of surface chlorophyll and GLOBEC observations of nutrient and phytoplankton profiles at inner and outer shelf stations on the Seward Line. The final form of the BHM process model component is comprised of a discrete version of the Nutrient-Phytoplankton-Zooplankton-Detritus LTL ecosystem model equations augmented to address iron limitation in the CGOA (i.e., NPZDFe), and including a vertical diffusion term to constrain the timing of the phytoplankton bloom in spring. Even in the relatively data-rich GLOBEC context, parameter estimation in the BHM requires guidance from a suite of calculations in a coupled physical-biological deterministic model—the Regional Ocean Model System coupled to an NPZDFe component (ROMS-NPZDFe). ROMS-NPZDFe simulations are used to: (1) validate the BHM formulation, (2) separate BHM limitations due to sampling from those due to LTL model approximations, and (3) obtain output distributions for zooplankton grazing rate and phytoplankton nutrient uptake rate using GLOBEC and SeaWiFS data for 2001. Uncertainty is evident from the spreads in output distributions for model parameters in the BHM. Experiments driven by simulated data from ROMS-NPZDFe helped to optimize the utility of GLOBEC observations for LTL ocean ecosystem model parameter estimation, given ever-present uncertainty issues. The ROMS-NPZDFe simulations are also used to build Bayesian statistical models as surrogates for the deterministic model. Two applications are briefly described. One estimates output distributions for selected ocean ecosystem parameters while accounting for spatial variability across the GLOBEC stations in the CGOA. A second application assimilates SeaWiFS data and simulated data from a ROMS-NPZDFe control run for 2002 to estimate complete fields of surface phytoplankton concentration, with associated spatial and temporal uncertainties.

The 20-year US GLOBEC (Global Ocean Ecosystem Dynamics) program examined zooplankton populations and their predators in four coastal marine ecosystems. Program scientists learned that environmental controls on zooplankton vital rates, especially the timing and magnitude of reproduction, growth, life-cycle progression, and mortality, determine species population dynamics, seasonal and spatial distributions, and abundances. Improved knowledge of spatial-temporal abundance and distribution of individual zooplankton taxa coupled with new information linking higher trophic level predators (salmon, cod, haddock, penguins, seals) to their prey yielded mechanistic descriptions of how climate variation impacts regionally important marine resources. Coupled ecological models driven by improved regional-scale climate scenario models developed during GLOBEC enable forecasts of plausible future conditions in coastal ecosystems, and will aid and inform decision makers and communities as they assess, respond, and adapt to the effects of environmental change. Multi-region synthesis revealed that conditions in winter, before upwelling, or seasonal stratification, or ice melt (depending on region) had significant and important effects that primed the systems for greater zooplankton population abundance and productivity the following spring-summer, with effects that propagated to higher trophic levels.

The goal of the Pacific Ocean Boundary Ecosystem and Climate Study (POBEX) was to diagnose the large-scale climate controls on regional transport dynamics and lower trophic marine ecosystem variability in Pacific Ocean boundary systems. An international team of collaborators shared observational and eddy-resolving modeling data sets collected in the Northeast Pacific, including the Gulf of Alaska (GOA) and the California Current System (CCS), the Humboldt or Peru-Chile Current System (PCCS), and the Kuroshio-Oyashio Extension (KOE) region. POBEX investigators found that a dominant fraction of decadal variability in basin- and regional-scale salinity, nutrients, chlorophyll, and zooplankton taxa is explained by a newly discovered pattern of ocean-climate variability dubbed the North Pacific Gyre Oscillation (NPGO) and the Pacific Decadal Oscillation (PDO). NPGO dynamics are driven by atmospheric variability in the North Pacific and capture the decadal expression of Central Pacific El Niños in the extratropics, much as the PDO captures the low-frequency expression of eastern Pacific El Niños. By combining hindcasts of eddy-resolving ocean models over the period 1950–2008 with model passive tracers and long-term observations (e.g., CalCOFI, Line-P, Newport Hydrographic Line, Odate Collection), POBEX showed that the PDO and the NPGO combine to control low-frequency upwelling and alongshore transport dynamics in the North Pacific sector, while the eastern Pacific El Niño dominates in the South Pacific. Although different climate modes have different regional expressions, changes in vertical transport (e.g., upwelling) were found to explain the dominant nutrient and phytoplankton variability in the CCS, GOA, and PCCS, while changes in alongshore transport forced much of the observed long-term change in zooplankton species composition in the KOE as well as in the northern and southern CCS. In contrast, cross-shelf transport dynamics were linked to mesoscale eddy activity, driven by regional-scale dynamics that are largely decoupled from variations associated with the large-scale climate modes. Preliminary findings suggest that mesoscale eddies play a key role in offshore transport of zooplankton and impact the life cycles of higher trophic levels (e.g., fish) in the CCS, PCCS, and GOA. Looking forward, POBEX results may guide the development of new modeling and observational strategies to establish mechanistic links among climate forcing, mesoscale circulation, and marine population dynamics.

This special issue summarizes the major achievements of the US Global Ocean Ecosystem Dynamics (GLOBEC) program and celebrates its accomplishments. The articles grew out of a final symposium held in October 2009 under the auspices of the National Academy of Sciences Ocean Studies Board (http://usglobec.org/Symposium). This special issue updates the US GLOBEC "mid-life" Oceanography issue (Vol. 15, No. 2, 2002, http://tos.org/oceanography/archive/15-2.html), which put forward many of the goals and activities of the program, but was published while field work was still being conducted and results had yet to be synthesized across regional programs. The present special issue highlights the advances in understanding achieved through the synthesis of regional studies and pan-regional comparisons.

End-to-end models were constructed to examine and compare the trophic structure and energy flow in coastal shelf ecosystems of four US Global Ocean Ecosystem Dynamics (GLOBEC) study regions: the Northern California Current, the Central Gulf of Alaska, Georges Bank, and the Southwestern Antarctic Peninsula. High-quality data collected on system components and processes over the life of the program were used as input to the models. Although the US GLOBEC program was species-centric, focused on the study of a selected set of target species of ecological or economic importance, we took a broader community-level approach to describe end-to-end energy flow, from nutrient input to fishery production. We built four end-to-end models that were structured similarly in terms of functional group composition and time scale. The models were used to identify the mid-trophic level groups that place the greatest demand on lower trophic level production while providing the greatest support to higher trophic level production. In general, euphausiids and planktivorous forage fishes were the critical energy-transfer nodes; however, some differences between ecosystems are apparent. For example, squid provide an important alternative energy pathway to forage fish, moderating the effects of changes to forage fish abundance in scenario analyses in the Central Gulf of Alaska. In the Northern California Current, large scyphozoan jellyfish are important consumers of plankton production, but can divert energy from the rest of the food web when abundant.

From the planning days preceding the establishment of the US Global Ocean Ecosystem Dynamics (GLOBEC) program, modeling was recognized as one of the program's pillars. In particular, predictions of future ecosystem states in an evolving climate system required new interdisciplinary approaches that brought together physicists, biologists, modelers, and observational scientists. The GLOBEC program coincided with, took advantage of, and contributed to significant advances in ocean modeling capabilities. During the GLOBEC years, computer power increased substantially to the point where coupled physical-biological models, at resolutions where important interactions are resolved, became feasible. Ocean models were maturing so that complex coastal processes were explicitly represented, and advances in different ways of modeling the biosphere, from Lagrangian individuals to Eulerian community-based, multitrophic models, were emerging. The US GLOBEC program addressed the question: How can we use all these developments to help us understand how ecosystems will respond to climate change? This paper includes a review of state-of-the-science modeling at the onset of the GLOBEC program and highlights the evolution of physical and biological models used for the program's target regions and species throughout the GLOBEC years, 1992–2012

In the 1970s, the International Decade of Ocean Exploration (IDOE) set the stage for an era of global ocean research programs (NRC, 1999). Although scientists had long explored the "seven seas," it was only in the late 1960s that observing the ocean at synoptic scales became feasible. This capability, together with the lessons learned from IDOE, allowed for the growth of major oceanographic initiatives. In particular, the late 1980s and the 1990s marked two decades of large oceanographic programs, two of which, the World Ocean Circulation Experiment (WOCE; http://www.nodc.noaa.gov/woce/wdiu/wocedocs/index.htm#design), and the Joint Global Ocean Flux Study (JGOFS; http://www1.whoi.edu), resulted in important advances and transformations in ocean research that fostered the subsequent development of the Global Ocean Ecosystem Dynamics program (GLOBEC; http://www.globec.org).

Researchers and funding agencies justify much oceanographic research by characterizing it as useful for better understanding ocean issues of interest to society at large. However, the direct transfer of ocean science to applications in the policy and management context remains a challenge. This paper explores how one large ocean science program, US Global Ocean Ecosystem Dynamics (US GLOBEC), has begun to take research results to applications in fisheries management, ocean observation systems, and applied ocean modeling. We review selected examples of this transition, and examine some characteristics of the program that have facilitated them. We also provide advice for future large oceanographic programs seeking to maximize the utility of their results.

From March 2002 to until April 2003 we investigated the seasonal nutrient and phytoplankton dynamics in the central Bornholm Basin (Baltic Sea) within the framework of the German GLOBEC Project. We choose a nested approach consisting of vertical fluorescence profiles, phytoplankton counts and nutrient analyses. The Fluoroprobe (MultiProbe, BBE Moldaenke) is capable of distinguishing four algal groups (Cryptophyceae, Cyanophyceae, Chlorophyceae, Bacillariophyceae + Dinophyceae). Winter nutrient concentrations were about 5 μM NO3 and 0.5 μM PO4 in the central Basin. The spring phytoplankton bloom was dominated by the diatom Skeletonema sp. and reached a maximum of about 270 μg C/l before the onset of the seasonal stratification. Protozooplankton was dominated by the Mesodinium rubrum ( a phototrophic ciliate = Myrionecta rubra) and reached a maximum biomass of about 200–300 μg C/l about 2 weeks after the demise of the diatom spring bloom. During summer, the water column was stratified and a subsurface maximum developed near the thermocline consisting of Bacillariophyceae, Cryptophycea and other phototrophic flagellates. Phytoplankton and protozooplankton biomass was generally low. Nutrient concentrations point towards a nitrogen limitation during this period. The stratification period ended during September and surface nutrient concentrations increased again. Protozooplankton reached a second maximum during September. With the Fluoroprobe small scale structures in the plankton community could be detected like a subsurface Cryptophyceae maximum near the thermocline that however, could not be confirmed by cell counts. The chlorophyll a estimate of the Fluoroprobe was in good agreement with the phytoplankton biomass estimated from counts. We conclude that only by combining modern sensing technology with microscopy, the small-scale dynamics and taxonomic spectrum of the plankton can be fully captured. [ABSTRACT FROM AUTHOR]

Drinkwater, K. F., Hunt, G. L. Jr, Astthorsson, O. S., and Head, E. J. H. 2012. Comparative studies of climate effects on polar and subpolar ocean ecosystems, progress in observation and prediction: an introduction. – ICES Journal of Marine Science, 69: .Background to and content of this part-product of the second ESSAS (Ecosystem Studies of Sub-Arctic Seas) symposium is provided, along with a call for future work of such nature to be continued, expanded, and enhanced, specifically with a view to determining global variations in resources and dynamics attributable to climate change. [ABSTRACT FROM PUBLISHER]