We know that different shorelines have different sensitivities to spilled oil.
Various coastal factors such as the types of rock substrate (geology), relief features such as the shape and topography of the beach (geomorphology), biological habitat (plants, seaweeds, seagrasses, and invertebrates), and wave exposure can all influence how oil interacts in the nearshore environment.
The same features impact our ability to protect, respond to, and clean-up oil and play huge roles in long-term impacts as we learned from previous oil spills such as the Exxon Valdez Oil Spill (EVOS).
In the U.S., oil spill responders rely on NOAA’s Environmental Sensitivity Indices (ESI) to rank relative risks to shorelines from spilled oil.
ESIs use information about the shoreline obtained from shoreline surveys to map both the different shore types along a coast, and the biological resources using those shorelines.
Following EVOS, it became obvious that detailed shoreline information was lacking, and much of what was available did not include the extensive intertidal habitats in the path of the oil.
Below, we describe our efforts to study coastal habitats.
ShoreZone Coastal Habitat Mapping
In 2001, Cook Inlet RCAC initiated a pilot project previously applied in Washington state and British Columbia. ShoreZone is a mapping and classification system that specializes in the collection and interpretation of spatially-referenced aerial imagery of the intertidal zone and nearshore environment, conducted during the lower tides of the year. The objective was to produce an integrated, searchable inventory of geomorphic and biological shoreline features so that the data can be queried and mapped for improved oil spill planning and response.
Remembering a prior “Worst-case Scenario” oil spill drill where a tanker ran aground on a rock south of the outer Kenai Peninsula coast, CIRCAC determined to obtain actual photographs of our shorelines at very low tides. Thought previous ShoreZone efforts did not include the imagery as a distributed product to ShoreZone users, our contractors at Coastal and Ocean Resources, Inc. agreed to work with us to develop a demonstration website where any user could access the imagery with the habitat data on-line. Remember, fifteen years ago, this was a relatively new concept and the tools to do so were not readily available.
Our first ShoreZone survey took place in central Cook Inlet and Kachemak Bay in 2001 and was funded by CIRCAC. The following spring, in April 2002, at the EVOS Trustee Council sponsored habitat mapping workshop, we highlighted our most recent survey and plans to develop on-line access. By summer 2002, there were additional surveys conducted, sponsored by CIRCAC, the Kenai Peninsula Borough, the EVOS Trustee Council, and the Coastal Impact Assistance Program of the State of Alaska. Within one more year, the National Park Service was partnering to map Katmai, Aniakchak, and Kenai Fjord National Parks, and, by 2005, we had funding to complete ShoreZone surveys and mapping of Kodiak Island.
Our continued efforts to promote ShoreZone among local organizations and state and federal agencies led to the creation of the Alaska ShoreZone Partnership (www.shorezone.org). CIRCAC’s pilot website, where habitat data and maps could be viewed along with video captures and photographs of the shoreline, successfully promoted ShoreZone and brought on additional partners. ShoreZone products have proven useful far beyond oil spill planning and response. They are used for research, education, permitting, resource management, recreation, search and rescue, habitat modeling, and many other efforts.
By 2005, NOAA’s Alaska Fisheries Science Center’s Regional Office agreed to administer and host the data and imagery from all of the various partners. Their role in developing a more robust website (http://alaskafisheries.noaa.gov/shorezone/ ) and overseeing data integration and quality control has led to a long-term partnership among dozens of organizations and agencies that have since imaged and mapped nearly 80% of Alaska’s shoreline. ShoreZone imagery and habitat data are now being integrated with other programs such as the ocean data portals at AOOS, including the Cook Inlet Response Tool (CIRT) described further below.
In 2009, CIRCAC took advantage of improved technology and higher resolution cameras to resurvey all of Cook Inlet, resulting in very high quality digital imagery and digital stills with which to illustrate the shoreline habitat information.
In addition to the ShoreZone aerial imagery and the mapped habitat data, we collected on-the-ground species-level data throughout our areas of concern. This portion of the program has also been expanded to others areas of Alaska. NOAA is serving this site-level data, integrating it with the rest of the ShoreZone information. CIRCAC has sponsored or partnered in the collection of data from hundreds of these stations providing a more detailed understanding of the types of organisms that are associated with the biological habitats mapped from the air.
Studies on special, unique, and sensitive coastal habitats in our areas of concern
CIRCAC has conducted studies to take a much closer look at certain shoreline types and habitats in our areas of concern, some discovered during ShoreZone aerial surveys, or to acquire detailed information not provided by ShoreZone.
During the aerial ShoreZone surveys around the Kodiak Island archipelago in 2002 and 2005, several beds of the giant kelp, Macrocystis, were discovered. Previous reports of individual plants had been seen as far north as Kodiak, but no actual kelp beds had been mapped or described. These kelp beds create different habitat than the other two canopy kelps (Nereocystis luetkeana or bull kelp and Eualaria fistulosa, or dragon kelp) that occur in the western Gulf of Alaska. Giant kelp, a perennial remaining year-round, can grow in a very dense band along the shoreline, potentially impacting shoreline access or oil spill response. Our studies in 2006 and 2009 included dive surveys, GIS mapping, voucher collections for university herbariums, and taking genetic tissue samples for archiving. Studying this kelp will help us evaluate its expansion and how it might affect other nearshore habitats.
Saltmarsh habitat, dominant in western Cook Inlet, its bays and smaller estuaries, is especially susceptible to long-term retention of spilled oil . Many of Cook Inlet’s salt marshes occur in the very high intertidal zone and are less likely to be oiled than lower intertidal habitats. However, if oiled during high tides, there is little that can be done to remove oil without serious damage, and the fine sediments and root structures of marsh plants can retain oil like a sponge. Marsh plants are very sensitive to slight changes in salinity. Saltmarsh habitat along Cook Inlet is often miles wide, and difficult to accurately portray using ShoreZone mapping methods. Thus, we sought additional methods to provide a higher level of habitat detail for these particularly sensitive habitats. Partnering with the Kachemak Bay Research Reserve (KBRR), we sponsored a series of field surveys to provide high resolution maps of some of the main salt marshes at risk to oil spills in Cook Inlet. Species lists and mapped plant assemblages at different tidal heights, along with aerial and on-the-ground photographs of the habitats were produced. This detail can be layered with the larger ShoreZone dataset.
Unique low-angle rock platforms and mudflats were evident in the ShoreZone aerial imagery of Kamishak Bay, in lower Cook Inlet. Some of these shorelines reveal miles of shoreline out from the upper beach during low tides. Very little historical data exists for some of these habitats, though they are downstream of potential Cook Inlet oil spills and provide habitat for spawning herring. CIRCAC has conducted several small site-specific assessments, and in the summer of 2015, we partnered with the National Park Service, NOAA, and the University of Alaska Fairbanks, with funding from BOEM, to conduct detailed assessments of the intertidal and subtidal habitats of rock and boulder platforms. This study will be expanded in the next several years to include other habitats. We collected information about the quantity and types of seaweeds and invertebrates that colonize these rock habitats and will relate them to the slight changes of tidal height measured across these very low-angle features (often having less than 2 degree slopes). This information will help us better understand these unique habitats and potentially provide baseline information for beaches at risk from future oil development and/or spills.
In 2000 and 2002, we conducted shoreline reconnaissance surveys of soft-sediment habitats in the upper and middle Inlet and in Kamishak Bay to identify potential sentinel species populations. Sentinel species are relatively long-lived (multi-year) and occur in quantities that would support periodic sampling for contaminant monitoring. Based on their feeding methods, sedentary invertebrates, such as bivalve clams, can be good indicators of exposure to pollutants. We evaluated for sentinels, described the sediments and beaches in which they lived, and collected representative samples of the sediment and clam tissues for contaminant analyses. A table was created of potential sentinel populations that could be periodically monitored over time or that could be quickly visited prior to, and after, oil exposure in the event of a spill.