LTER Grows

NSF Awards $10 Million to Ocean Sites for Long-Term Ecological Research

Coral reefs and coastal upwelling ecosystems are the foci of two new LTER sites awarded funding this summer by the National Science Foundation (NSF). With the addition of the California Current Ecosystem (CCE) and the Moorea Coral Reef (MCR) LTER sites, there are now 26 NSF-funded sites in the LTER network. Henry Gholz, director of NSF’s LTER program, noted that the two sites significantly augmented the LTER network, which hitherto included only one marine site—Palmer in the Antarctic. The awards ensure that high biodiversity and productivity ecosystems in most of the world’s major biomes, both on land and in the oceans, are represented. The two newest sites will receive approximately $820,000 for the next six years, for a total of about $5 million each.
The following two articles introduce the two newest members of the LTER Network.

The California Current Coastal Pelagic Ecosystem (CCE) LTER

Mark D. Ohman
Lead PI, CCE LTER, Scripps Institution of Oceanography, University of California, San Diego

Fig. 1. Multidecadal variability in (a) ocean thermal stratification, (b) the Pacific Decadal Oscillation index (annual averages, Mantua et al. 1997), (c) biomass anomalies of the krill Nyctiphanes simplex, (d) biomass anomalies of the uncommon doliolid D. denticulatum, and (e) biomass of an assemblage of salps that predominate in the cool phase. All records begin in 1950 (from Ohman and Venrick 2003). Dashed lines indicate hypothesized nodes.

The new California Current Ecosystem (CCE) LTER site (http://ccelter.sio.ucsd.edu/) represents a pelagic (i.e., the ocean water column) coastal upwelling biome, as found along the eastern margins of all major ocean basins. These are among the most biologically productive coastal ecosystems in the world. Research at this site will focus on mechanisms leading to transitions over time between different states of the pelagic ecosystem. Observations from the remarkable California Cooperative Oceanic Fisheries Investigations (CalCOFI) coastal ocean time series—currently in its 55th year—demonstrate the effects of external factors in forcing alterations to this ecosystem on multiple time scales. These factors include a warming trend that has been documented over the past 5 decades, the long term warming and cooling cycles (ca. 20-30 years) represented by the Pacific Decadal Oscillation, and the year-to-year temperature fluctuations dominated by El Niño. Combinations of these processes, together with interactions among living organisms, can lead to ecosystem responses that may be manifested as relatively abrupt transitions (Fig. 1).

Research Focus

The CCE site proposes to evaluate four hypothesized mechanisms for these kinds of rapid ecosystem transitions:

• Localized food web changes in response to changes in ocean temperature stratification and nutrient supply
• Sustained, irregular alongshore transport of different assemblages of organisms
• Changes in cross-shore transport and loss/retention of organisms
• Altered predation pressure

Our site will address these hypotheses with an integrated research program having three primary elements:

Fig. 2. Temporal variation in the average depth of the nitracline, defined as the first depth where NO3 > or = 1.0 µM, for the CalCOFI region from the shore out to station 70. Vertical spike in 1997-98 reflects El Niño-related deepening of the nitracline. Horizontal lines illustrate means for 1984-1998 and 1999-2003 (Goericke, unpubl.).

(1) Experimental Process Studies will initially focus on the hypothesis of localized food web changes in response to changes in water column stratification. Here we will use space as a substitute for time, since many of the temporal changes that are observed in this region have clear spatial analogs. For example, the nitracline depth (depth where nitrate first exceeds 1 µM) deepened dramatically during the 1997-98 El Nino, after which it may have returned to a shallower average depth (Fig. 2). At a single point in time we find spatial variations in nitracline depth within our LTER region that encompass these temporal variations (Fig. 3). Variations in nitracline depths over this range are associated with changes in composition of the food web’s primary producers, in this case tiny unicellular cyanobacteria, which show highest abundances at intermediate nitracline depths (Fig. 4). We will exploit such spatial differences to develop continuous functions that describe growth and loss rates of different members of the plankton assemblage in relation to nitracline depth. These functions will then be used in our coupled bio-physical models to simulate the ecosystem effects of changes in nitracline depth over time.

Fig. 3. Spatial difference in Temperature (T), NO3 and Chl a concentration, in 3 regions of the CalCOFI domain: inshore upwelling, Core California Current, and stably stratified offshore. Note changing scale of Chla. (E. Venrick, unpubl.).

(2) Time Series Studies will evaluate our alternative hypotheses, using time series measurements from a variety of CCE LTER research stations (Fig. 5). These measurements will include (a) a quarterly measurement program at sea that will capitalize on and significantly enhance the CalCOFI time series by also assessing the microbial community, dissolved and particulate organic matter, and iron geochemistry; (b) satellite remote sensing observations, including phytoplankton pigments and sea surface temperature; and (c) frequent temporal measurements at different nearshore locations through collaborations with coastal observing systems. These collaborations include the Santa Barbara coastal (SBC) LTER site, the newly developed SCCOOS (Southern California Coastal Ocean Observing System) program, and our Education and Outreach partner, the Ocean Institute.

Fig. 4. Nonlinear relationship between the abundance of coccoid cyanobacteria Synechococcus sp. and the depth of the nitracline (from Collier and Palenik 2003).

(3) Modeling studies will be an integral part of this site. Models will be used to help interpret and understand the dynamics underlying observations; to provide a platform for hypothesis testing through numerical experiments; and to provide a means for dynamic interpolation between observations in space and time. Three different types of models will be employed: coupled 4-D, eddy-resolving bio-physical models of the California Current ecosystem based on ROMS (the Regional Ocean Modeling System); nonlinear time series hindcast models; and control volume property flux models. Control volume models will enable us to estimate net fluxes of properties such as heat, salt, nutrients, oxygen and phytoplankton biomass through the 3D box defined by the stations and the coast (Fig. 6), by assuming that the convergence of mass into the box created by horizontal currents is balanced by upwelling-related divergence of mass out of the box, and solving for the net flux.

Fig. 5. CCE LTER station plan, including CalCOFI stations, control volume boundaries, NODC buoys, Santa Barbara Coastal kelp moorings, Ocean Institute at Dana Point, and the Scripps pier.

Information and Outreach

In addition we will advance Information and Data Management to support data and metadata internally, and facilitate the exchange of research findings with other LTER partners, educators, the general public, and policy makers. Our information system will contain multiple layers for storage, access, and discovery, and act as an interface to users, other systems, and analysis packages. Documentation and data storage will be organized through an electronic hub at the Integrative Oceanography Division (IOD) at the Scripps Institution of Oceanography. Our Education and Outreach program will team scientists with California COSEE and three external partners to engage the “K through grey” community in both the process and the understanding gained from this research. We will train undergraduates, graduate students (in collaboration with a Scripps-based IGERT), and postdoctoral scholars across disciplinary boundaries. Through collaborations with informal science education organizations, we expect to reach many K–12 schoolchildren each year, including local low-income and minority students.

Fig. 6. Three-dimensional Control Volume defined around the open boundaries of the CCE study site.

Site Location

The CCE site is in the southern sector of the California Current, which is part of the great clockwise circulation pattern of the North Pacific. Our site extends from the major upwelling site at Point Conception to the U.S.-Mexican border, and from the shoreline approximately 500 km offshore. This region lies between ca. 30-35º N and 117-124º W.

Participants in this site come from the Scripps Institution of Oceanography/U.C. San Diego, the Southwest Fisheries Science Center of NMFS/NOAA, Pacific Fisheries Environmental Laboratory, Duke University, Georgia Institute of Technology, and the Point Reyes Bird Observatory.

The proposed study region is an ideal location for an LTER site for many reasons, including:

• Five decades of climate and ecosystem context provided by CalCOFI
• Inclusion of a biogeographic boundary region, making it an early sentinel of climate change
• Pronounced spatial gradients that represent much of the dynamic range of the entire ocean environment
• Anoxic basins that provide a unique connection to paleoceanographic studies
• An existing physical ocean circulation model of the region that will permit rapid advances in the development of coupled bio-physical models relating to ecosystem transitions.

We look forward to working together actively with colleagues in the LTER network to compare coastal pelagic upwelling ecosystems with other biomes, with respect to the five core research themes of LTER as well as other topical issues.

References
Collier, J. L., and B. Palenik. 2003. Phycoerythrin-containing picoplankton in the Southern California Bight. Deep-Sea Research II 50: 2405-2422.
Mantua, N. J., S. R. Hare, Y. Zhang, J. M. Wallace, and R. C. Francis. 1997. A Pacific interdecadal climate oscillation with impacts on salmon production. Bulletin of the American Meteorological Society 78: 1069-1079.
Ohman, M. D., and E. L. Venrick. 2003. CalCOFI in a changing ocean. Oceanography 16: 76-85.

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The Moorea Coral Reef (MCR) LTER

New site offers scientists opportunity to study the structure, function, and dynamics of coral reef ecosystems

The newly established Moorea Coral Reef (MCR) LTER site will focus on the coral reefs that surround the south Pacific island of Moorea (17º30'S: 149º50'W). Moorea, located in the Society Islands of French Polynesia, also is home to the University of California’s Richard B. Gump South Pacific Research Station (http://moorea.berkeley.edu) which will serve as the logistical base for all MCR related field operations.

UC Berkeley’s Gump Research Station property (lower left), base of field operations for the MCR LTER, looking northeast to the Maharepa Lagoon back reef and reef crest on the north shore of Moorea. Photo: R. Wilder

Scientists rank coral reef ecosystems near the top of all ecosystems with respect to annual total gross productivity and biodiversity despite the fact that these systems typically occur in warm, nutrient-poor waters. The large and diverse communities of corals found on coral reefs are fueled by efficient nutrient recycling processes. In turn, stony corals and their photosynthetic zooxanthellae (single-celled algae that live symbiotically within the coral tissue and provide photosynthetic energy to the coral host) serve as the foundation upon which tens of thousands of other species rely. Indeed, more than one third of all species of marine fishes occur in coral reef ecosystems despite constituting far less than one percent of the ocean bottoms.

Because of their complexity, scientists have an incomplete understanding of the multitude of abiotic forcing functions—external variables like temperature, currents, light, etc.—and biotic processes that collectively determine the structure, function, and dynamics of coral reef ecosystems. Global climate change and other perturbations are predicted to cause sweeping changes on coral reefs in the coming decades. A combination of monitoring and experimental studies carried out at a range of spatial scales will be necessary to elucidate the mechanistic basis of change in these systems.

Research Focus

Research at the MCR site will estimate long-term trends and address key gaps in our understanding of these complex ecosystems through long-term observations and experiments supplemented by shorter-term process studies. The goals of MCR LTER are to better understand coral reef processes that drive the functions of this ecosystem, the nature of coral reef animal and algal community structure and diversity, and the factors that determine the abundance and dynamics of related populations. These goals will be met through studies of trophic dynamics, such as the relationships among corals, fishes, and zooplankton; the physiological ecology of corals and their zooxanthellae symbionts; controls of reef productivity and ecological controls; and functional significance of biodiversity.

Sally Holbrook, co-PI of the MCR LTER, and former graduate student Bill Douros, set up an experiment in a lagoon at Moorea, French Polynesia. Photo: R. Schmitt

Two additional research components cut across these themes and will help to integrate and generalize the various research endeavors. These include an explicit focus on physical-biological coupling over multiple scales, and hydrodynamic, food-web, and ecosystem modeling. The understanding derived from the research will allow more accurate predictions of how coral reef ecosystems respond to environmental change, whether human-induced or from natural cycles. It will also serve as a knowledge base to inform government officials, resource managers, and others charged with the conservation and management of coral reefs.
Educational training and outreach both will be important components of the MCR site. Moorea will provide training in research and team research experiences for undergraduate and graduate students, as well as engage in post-doctoral training. One goal of the training will be to build linkages between US students and scientists and those in South Pacific and Pacific Rim nations. Outreach activities associated with MCR LTER will include K-12 programs in Southern California as well as community and school outreach in French Polynesia, and an internship program for Tahitian university students.

The four principal investigators for the award are affiliated with the University of California at Santa Barbara (Russell Schmitt and Sally Holbrook), and California State University at Northridge (Robert Carpenter and Peter Edmunds). In addition, scientists at the University of California at Santa Cruz, Scripps Institution of Oceanography, the University of California at Davis, and the University of Hawaii comprise the interdisciplinary team on the project. Research activities will include field monitoring and process studies, plus laboratory experimentation and modeling by the research team of ecologists, geneticists, physical and biological oceanographers, physiologists, modelers, biogeochemists, and molecular microbial biologists.

Location

Moorea is an ideal locality for an LTER site focused on coral reef ecosystems. All major coral reef types are present, are in good condition, and are highly accessible the year round. The UC Berkeley’s Gump Research Station provides an excellent base for field and lab operations, and the station is just a 30-minute ferry ride from the international airport on the island of Tahiti. There are daily non-stop flights to Tahiti from the west coast of the United States, and these flights last only a couple of hours longer than flights to Honolulu.

An adult orange-fin anemonefish and juvenile three-spot dascyllus on their shared host sea anemone in a lagoon at Moorea, French Polynesia. Photo: R. Schmitt

Moorea is a small volcanic island with an offshore barrier reef that forms shallow, narrow lagoons around the 60 km (40 mile) perimeter of the island. The rich research opportunities afforded by the reefs of Moorea are greatly facilitated by the existence of appropriate infrastructure and the ease with which field research can be conducted. The Gump Research Station has been operated by the University of California and administered by UC Berkeley since the early 1980s. Station facilities include two long-standing laboratory buildings with all the appropriate facilities, plus a third laboratory building containing research labs, a molecular lab, an IT center, and office space, which is nearing completion. In addition, the station has a flow-through sea water system, a dock, launch ramp, a fleet of small boats and vehicles, as well as a Scuba compressor and dive lockers. Station housing includes a dormitory and bungalows.

“We view the Moorea Coral Reef LTER to be the flagship research program of the Station,” says Neil Davies, Executive Director of the Gump Research Station, “and we look forward to a long and productive partnership.”

"All of us associated with the Moorea Coral Reef LTER are thrilled to be part of the LTER network. It will afford a fantastic opportunity to interact with scientists working in a diverse array of ecosystems, and to conduct comparative studies to seek a more general understanding of the structure and function of natural systems,” says Co-PI Peter Edmunds.