INAUGURAL NOAA MCARTHUR II RESEARCH CRUISE INVESTIGATES NEARSHORE OCEAN CONDITIONS, SEDIMENT CHEMISTRY, INVERTEBRATE BIODIVERSITY, AND FISH COMMUNITIES ALONG THE PACIFIC NORTHWEST CONTINENTAL SHELF

Sept. 29, 2003 — Estuaries are ecological transition zones, integrating features of the watersheds they drain with those of the marine environment. As a result, changes in either watersheds or nearby, coastal waters can have significant impacts on the nations estuaries. For example, large-scale ocean circulation patterns — which vary over long time periods — determine the strength and location of currents along the coast, and thus affect conditions in the nearshore ocean and estuaries throughout the region. Likewise, periodic seasonal differences in the weather and ocean affect estuaries on shorter time scales — summers tend to be dry with winds from the northwest facilitating upwelling in the nearshore marine environment, while winters are typically wet with storms from the southwest. Seasonal upwelling of deep ocean water occurs along the coasts of Washington, Oregon and California and leads to episodes of dense phytoplankton production and rapid growth of zooplankton communities. Upwelling typically occurs between March and September when the nearshore waters are driven southwest by prevailing northwesterly winds. After several days of strong northwest winds, surface waters near the coast are transported offshore due to the rotation of the Earth (i.e., the Coriolis Force). Offshore movement of surface waters results in the reciprocal movement of deep, cold nutrient-rich waters to the surface — also known as upwelling. Most active upwelling is restricted to a narrow band of ocean water approximately five to 15 miles from shore, although the process of seasonal upwelling has great influence over currents across the entire continental shelf. Conversely, periodic relaxation of upwelling results in the onshore movement of ocean waters, and brings with it swarms of planktonic larvae and pulses of recruitment by crabs, shrimp and shellfish. Upwelling of cold nutrient-rich ocean water is an important coastal process that contributes to high levels of biotic productivity throughout the waters of the Pacific northwest. From late fall to early spring, a low pressure atmospheric cell moves into the Gulf of Alaska, spawning fierce storms that blow on-shore from the west and southwest. These storms drive surface waters northward along the coast and eventually push them into the nearshore and estuarine waters, thus forcing ocean water to sink or down-well near the shore. Fall and winter rain storms can affect the nearshore zone when coastal rivers discharge large volumes of freshwater laden with sediment and debris, as well as dissolved minerals and other nutrients from the watershed. Therefore, both ocean upwelling or storm events can change water properties in estuaries throughout the region — often in as little one or two tidal cycles. Lastly, periodic forcing by El Niño-Southern Oscillation events and longer-scale decadal regime changes can also profoundly affect maritime climate and regional ocean conditions, as well as tidal circulation in the estuaries. Other oceanic and atmospheric changes operate more slowly; over time scales of decades, centuries and longer.

Estuaries are also biological “hot spots” along the coast. They serve as permanent or temporary home to a wide variety of organisms — some of marine origin, others from upstream, and some unique to the mixing zone. Biological productivity in this mixing zone is especially high, due to an abundance of food and tidal energy. Estuarine habitats — marshes, eelgrass beds, mudflats and tidal channels — also serve important roles in the life cycles of marine and anadromous species, including crab, salmon, herring, migratory waterfowl, shorebirds and hundreds of less well-known species.

Although estuaries are influenced by the combination of natural forces and, therefore, experience great variability in temperature, salinity, tides, and river flow, estuarine organisms are often highly naturally resilient to disturbance. However, the cumulative effects of human alterations such as filling, diking, dredging and wood removal; the introduction of non-indigenous species; and excessive waste disposal have reduced the functional capacity and natural resiliency of these ecosystems. Meanwhile, demands on ocean and coastal resources from estuaries continues to rise due to increasing population and economic development. Many of the coastal watersheds in the Pacific Northwest have already experienced significantly altered natural ecosystems due to the settlement, exploitation and development of its resources. Declines of coastal salmon stocks, for example, forced Oregon and Washington state governors and agencies, federal agencies, and local communities to rally together to find "the cause" of this decline and develop plans to "restore" these stocks in coastal streams.

Ecological Indicators
Fortunately an integrated approach to monitoring aquatic ecosystems can be used to characterize ecosystem health, identify natural vs. man-made stressors and quantify observed trends — all information which can be used to improve decision making processes and land management practices. A critical component of this integrated monitoring approach involves “ecological indicators,” which serve as scientific measures to assess the ecological status and trends in the health of ecosystems and their component parts. For example, ecological indicators of change in estuaries often include the following:

• Change in area of estuarine habitats (acres and percent), including estuarine tidal marshes, swamp habitat and eelgrass beds.
• Introduction of aquatic nuisance species (occurrence and extent) — Human-induced stress and disturbance may further increase the vulnerability of natural habitats to the establishment and spread of invasive species. Although the effects of invasions by non-native species are not well understood, it is generally acknowledged that such invasions may be widespread and of sufficient magnitude to precipitate profound ecological changes in estuarine and nearshore marine communities.
• Freshwater inflow (flow rate and timing) and water quality trends — both of which are of vital importance in the maintenance of characteristic estuarine plant and animal communities.

Ecological indicators allow researchers, managers and the public to:

• Assess changes in the condition of the ecosystem and progress towards achieving management goals for its sustainable well-being;
• Understand better how human actions affect the ecosystem, and determine the types of programs, policies or regulations needed to address the environmental impacts;
• Gain a clearer understanding of existing and emerging environmental problems and their solutions;
• Provide information that assists the public and stakeholders in participating in informed decision making;
• Provide information that will help managers better assess the success of current programs and provide a rationale for future ones; and
• Provide information that will help set priorities for research, data collection, monitoring and clean-up programs.

The NOAA Ocean Service has used ecological indicators and an integrated approach to monitoring aquatic ecosystems over the last few decades. However, rather than identifying a single indicator of coastal ecosystem function and health, NOAA researchers use a broader systems approach in the belief that sustainable management of such a complex and diverse system will only be possible by integrating a physical, biological and chemical understanding of the ecosystem. To accomplish this, NOS researchers develop integrated “multiple indicator” assessments that describe an ecosystem, assess its current condition or health, forecast future ecological health based on current management practices and evaluate alternative management options and their consequences. The NOS approach to estuary research produces information that increases the nation’s understanding of these complex coastal systems and improves its ability to protect and restore habitats within them. A primary example of this type of research was the work conducted this summer onboard the newly commissioned NOAA Ship McArthur II to investigate nearshore ocean conditions, sediment chemistry, invertebrate biodiversity and fish communities along the Pacific Northwest continental shelf.

Research onboard the NOAA Ship McArthur II
The newly commissioned NOAA Ship McArthur II’s first mission was a joint survey by NOAA, the Environmental Protection Agency and partnering West Coast states (Washington, Oregon and California) of the ecological condition of aquatic resources in near-coastal waters along the U.S. western continental shelf — in the region from Cape Flattery, Wash., to San Francisco, Calif. Jeffrey Hyland from the NOAA National Center for Coastal Ocean Science and Walt Nelson from the U.S. Environmental Protection Agency (Western Ecology Division) jointly sponsored the collaborative survey. The study is an expansion of EPA’s Environmental Monitoring and Assessment Program, which seeks to assess condition of the nation’s environmental resources using multiple indicators of ecological condition.

As an extension of the recent EMAP assessments conducted in West Coast estuaries (1999-2002), the survey of the Pacific northwest continental shelf waters constitutes a pilot project within the National Coastal EMAP survey (CEMAP). As such, the sampling effort also represents the first-ever comprehensive assessment of ecological conditions in the coastal waters between depths of 30 to 120 meters along a major portion of the U.S. western continental shelf. The month-long investigation was organized into three distinct legs: Leg I. Washington (Cape Flattery to the mouth of the Columbia River / June 1-8); Leg II. Oregon (Astoria, Ore., to Cape Mendocino, Calif. / June 8-16) and Leg III Northern California (Cape Mendocino to San Francisco, Calif. / June 18-26). The survey team conducted sampling activities at each of 146 oceanographic stations (about 50 each in Washington, Oregon and California). In doing so, they will be able to compare statistical estimates of marine ecological conditions among the three states and conduct broad-scale regional comparisons with other sections of the coastal United States. At each station, sampling of the water column and benthos (i.e., bottom waters) was conducted to assess the condition of multiple indicators of the marine environment, including:

• Water column indicators (i.e., thermocline depth, conductivity, salinity, temperature, dissolved oxygen, light transmittance, chlorophyll A levels, suspended solids, nutrients ) — used to gather information about the movement and structure of water masses, while chemical analysis of water samples provided information about the origin of water masses and their ability to support life;
• Benthic habitat conditions (sediment particle sizes, organic content);
• Concentrations of chemical contaminants in sediments (metals, pesticides, PCBs, PAHs);
• Community structure and composition of benthic invertebrates (diversity and abundance of invertebrates >1.0 mm);
• Condition of targeted demersal fishes (contaminant body burden, pathological disorders and anomalies) — fish that rest on the sea bottom, but swim and feed in the water column.

Coastal EMAP Oregon: Links between Estuaries and the Nearshore Pacific Ocean
Steven Rumrill (NOAA Research Program Coordinator for the South Slough National Estuarine Research Reserve and the Oregon Institute of Marine Biology) was pleased to participate in the Leg II — NCA survey of the continental shelf waters offshore of Oregon and northern California. Rumrill is a veteran of several previous cruises aboard the older McARTHUR where he conducted investigations of physical and biotic links between Oregon estuaries and the nearshore Pacific Ocean as part of the NOAA Pacific Northwest Coastal Ecosystem Regional Study. “Daily flooding by ocean waters is the primary driving mechanism for many ecological processes within the marine-dominated regions of Oregon estuaries,” said Rumrill as the McARTHUR II conducted pre-dawn sampling within sight of the mouth of Coos Bay, Ore. “Tidal flushing controls the delivery and transport of marine and riverine sediments, as well as the input of important nutrients and influx of mature larvae. Increased understanding of biological processes in the nearshore waters will lead to improved understanding and appreciation of the essential role of the ocean in Pacific northwest estuaries.” Rumrill added, “participation in this comprehensive regional assessment has provided a tremendous opportunity to put our focused studies of the local Coos, Umpqua and Coquille estuaries into the context of connections with the entire continental shelf. Coos Bay and South Slough are separate arms of an estuary formed by the drowning of a river mouth. Ocean tides flood the estuary twice each day, and the tidal exchange and flushing are dramatic, especially during the summer when freshwater inputs from streams are low. In order to understand the ecological dynamics of the estuary, we need to also understand the behavior of continental shelf waters at our doorstep."

This and similar work will help provide coastal resource agencies, fisheries biologists and port managers with the factual information they need to make sound stewardship and management decisions closer to shore. Results generated by the study will also give NOAA and EPA scientists the ability to make unbiased statistical estimates of the spatial extent of the Pacific northwest continental shelf study area that exhibit degraded versus non-degraded conditions. This information can then be used as a baseline to quantify long-term trends in the marine environment, to identify links in nearshore coastal environments to the characteristics of specific estuaries, and to provide coastal resource managers with a fundamental regional characterization to evaluate future changes in relation to potential human or natural disturbances.

Relevant Web Sites
NOAA National Estuarine Research Reserve

NOAA El Niño Theme Page

NOAA FUNDS NEW PACIFIC SALMON STUDY

NOAA Ocean Service

NOS approach to estuary research

NOAA Ship McArthur II

EPA’s Environmental Monitoring and Assessment Program

Coastal EMAP survey

South Slough NERR Team Investigates Estuarine Links to Pacific Ocean

NOAA Pacific Northwest Coastal Ecosystem Regional Study

Media Contact:
Glenda Tyson, NOAA's Ocean Service, (301) 713-3066 ext. 191 or Ben Sherman, NOAA's Ocean Service, (301) 713-3066 ext. 178