National Park Service

Southwest Alaska Network (SWAN)

Marine Nearshore Monitoring

data entry on the coast of Kenai Fjords
Entering data while surveying the intertidal zone in Kenai Fjords National Park, 2012

Monitoring Reports

Protocol Documents

Trip Summaries

Subject Flickr Photo Galleries

Subject YouTube Videos

Questions

Gulf Watch Alaska logo
  • How will nearshore resources within the Parks change over time?
  • What are the potential causes for observed changes?

Objectives

  • Assess changes by annually monitoring vital signs at various locations within the SWAN parks
  • Describe changes and assess potential causes by comparing values for different vital sign metrics (e.g. number of sea otters) over time
  • Examine how the relative extent of change over time varies among locations

Overview

The nearshore can be defined as that section of the marine ecosystem that extends from the high tide line offshore to depths of about 20 m. The nearshore is considered an important component of the Southwest Alaska Network of National Parks (SWAN) and the Gulf of Alaska marine ecosystem because it provides:

  • A variety of unique habitats for resident organisms (e.g. sea otters, harbor seals, shorebirds, seabirds, nearshore fishes, kelps, seagrasses, clams, mussels, and sea stars),
  • Nursery grounds for marine animals from other habitats (e.g. crabs, salmon, herring, and seabirds),
  • Feeding grounds for important consumers, including, killer whales, harbor seals, sea otters, sea lions, sea ducks, shorebirds, brown bears, and many fish and shellfish,
  • A source of animals important to commercial and subsistence harvests (e.g. marine mammals, fishes, crabs, mussels, clams, chitons, and octopus),
  • An important site of recreational activities including fishing, boating, camping, and nature viewing,
  • A source of primary production for export to adjacent habitats (primarily by kelps, other seaweeds, and eelgrass), and
  • An important triple interface between air, land and sea that provides linkages for transfer of water, nutrients, and species between watersheds and offshore habitats.

Justification and Importancce

The nearshore is broadly recognized as highly susceptible and sensitive to a variety of both natural and human disturbances on a variety of temporal and spatial scales. For example, observed changes in nearshore systems have been attributed to such diverse causes as global climate change, earthquakes, oil spills, human disturbance and removals, and influences of invasive species.

Nearshore systems are especially good indicators of change because organisms in the nearshore are relatively sedentary, accessible, and manipulable. Also, in contrast to other marine habitats, there is a comparatively thorough understanding of mechanistic links between species and their physical environment that facilitates understanding causes for change. Additionally, the nearshore is the one habitat within which it is most likely that we will be able to detect relatively localized sources of change, tease apart human induced from naturally induced changes and, provide suggestions for management actions to reduce human induced impacts.

Because many of the organisms in the nearshore are sessile or have relatively limited home ranges, they can be geographically linked to sources of change with a reasonable degree of accuracy.

USGS biologists observing foraging sea otters with high resolution telescopes to determine foraging success, composition and size of prey, and number of prey items recovered, KATM 2012.
An NPS biologist surveys for sa otters in Katmai National Park and Preserve, 2012

Resource Brief - Sea Otters, 2011

Monitoring Reports

Protocol Documents

Monitoring Objectives

  • Estimate distribution and density of sea otters in SWAN parks
  • Estimate age composition of dying sea otters
  • Investigate role and response to the structure and function of nearshore communities

Sampling Design

To estimate sea otter abundance and distribution, systematic aerial surveys of transects within marine habitats between the shoreline and the 100 m bathymetric contour are sampled.

Collection of sea otter carcasses that become beach-cast provides an estimate of the age composition of animals dying in the population. Age specific likelihood models are used to evaluate how changes in survival contribute to changes in the age distributions of animals that are found dead on the beaches. Systematic searches of depositional beaches or haul-out sites are conducted annually to obtain estimates of ages at death based on cementum annuli in teeth.

Diet is determined by direct observation. Because sea otters are relatively shallow divers, most of their foraging is close to shore, and because they bring their prey to the surface for consumption, their diet is relatively easy to determine through direct observation with high resolution telescopes. The purpose of collecting data on sea otter diet is to quantify foraging success and intensity as well as the types, number, and relative sizes of prey being eaten by sea otters. These data provide information on the status of sea otter populations (amount and types of food obtained per unit effort) as well as the relative abundance of prey items (as measured indirectly by sea otter foraging success and prey selection).

Importance/Issues

Sea otters (Enhydra lutris) are important mammalian members of the nearshore community throughout the north Pacific and are the only marine mammal that relies exclusively on shallow or intertidal macro-invertebrates as prey. Sea otters were selected as a SWAN vital sign because they are a textbook example of "keystone" carnivore. By consuming grazers—the animals that feed on kelp—sea otters dramatically change the structure and complexity of their ecological community resulting in communities characterized by diverse and abundant algae and relatively few large grazing invertebrates such as urchins.

Other well documented sea otter mediated predation effects include reduced biomass and size distributions of many large and conspicuous invertebrates, such as clams, mussels, urchins, and crabs. Sea otters tend to be relatively sedentary in comparison to other marine mammals; eat large amounts of food; have an incidence of disease that is correlated with contaminants; and have broad appeal to the public. In September 2005, the Western Alaska Stock of sea otter, which include the Katmai NP, but not the Kenai Fjords, was federally listed on as threatened.

kelp Katmai 2012
NPS and USGS biologists survey the intertidal zone above a kelp bed, Katmai National Park and Preserve, 2012

Resource Brief - Kelp and Eelgrass, 2011

Monitoring Reports

Protocol Documents

Objectives and Sampling Design

  • Document broad-scale decadal changes in occurrence and distribution of canopy kelps, eelgrass, and surfgrass along the entire length of the SWAN coastline using oblique aerial video imagery (Harper and Morris 2004)
  • Document smaller-scale annual changes in species composition, distribution, and relative abundance of kelps and seagrasses within intensively sampled sites

Importance/Issues

Kelp and seagrass were identified as a SWAN vital sign because they are "living habitats" that serve as a nutrient filter and provide understory and ground cover for planktivorous fish, clams, urchins, and a physical substrate for other invertebrates and algae. Kelps are the major primary producers in the marine nearshore and because they are located in shallow water they could be adversely impacted by oil spills and other human-related activities.

counting marine intertidal invertebrates, Kenai Fjords
Intertidal monitoring, Kenai Fjords National Park 2012

Resource Brief - Intertidal Invertebrates, 2011

Inventory Reports

Monitoring Reports

Protocol Documents

Subject Flickr Photo Galleries

Subject YouTube Videos

Objectives

  • Monitor long-term trends in invertebrate species size, distribution, density, percent cover, etc. at randomly selected sites in sheltered rocky and mixed sand-gravel habitats as well as specified mussel bed sites
  • Monitor status and trends in the concentration of metals, organochlorides, PCBs, and mercury in mussel tissue

Importance/Issues

Intertidal marine invertebrates were selected as a SWAN vital sign because they provide a critical prey resource for various types of sea birds (e.g. some shorebirds and most sea ducks), marine mammals (sea otters, Enhydra lutris), marine fishes and larger invertebrates (e.g. octopus), and may provide important sources of nutrients and energy to some terrestrial carnivores (e.g. black and brown bears (Ursus americanus and Ursus arctos), that may seasonally forage in marine habitats.

Two habitat types are widely recognized in supporting important, although taxonomically quite different, intertidal invertebrate communities.

The rocky intertidal community typically supports diverse and abundant kelps (Fucus sp. and Laminaria sp.) and other algae with invertebrate fauna dominated by mussels (Mytilus trossulus), barnacles (Balanus and Semibalanus sp.) limpets (Lottia sp.) and snails (Nucella sp.). Predatory sea stars (Pyncopodia helianthoides, sp. and Evasterias sp.) are also conspicuous and common species in the rocky intertidal.

The soft-sediment intertidal habitats are characterized by unconsolidated sediments ranging in grain size from fine clays to cobble boulders. Common marine macro-invertebrates (>5 mm), include a variety of clams (Leukoma staminea, Saxidomus giganteus, Mya truncata, Macoma sp.). Large benthic invertebrates that feed the higher trophic levels are ecologically diverse in terms of habitat and trophic requirements; have a wide range of physiological tolerances and feeding modes, and are relatively sedentary with relatively short generations times. Measurements of species diversity, densities, size class distributions, and contaminant levels in intertidal invertebrates will provide useful inference relative to causes of change that will be detected in higher level consumers that occupy nearshore food webs.

USGS and SWAN biologists conducting skiff-based marine bird and mammal counts, Katmai National Park and Preserve 2006.
USGS and SWAN biologists conducting skiff-based marine bird and mammal counts, Katmai National Park and Preserve 2006.

Resource Brief - Marine Birds, 2011

Monitoring Reports

Subject Flickr Photo Galleries

Objective

  • Estimate the species composition, distribution, and density of marine birds and mammals that occur within nearshore habitats

Sampling Design

The marine bird survey sampling unit is a strip transect, up to 5 km long by 200 m wide by 100 m high that is centered 100 m offshore of the sea water tidal level at the time the survey is conducted. A series of systematically located, non-contiguous transects that cover all shorelines, including islands, are systematically selected with a random start point. Bird and mammals counts are made from skiffs and data is directly entered into a laptop computer linked to a GPS and using the survey software that visually displays the shoreline, the transect line, and the survey vessel location. Species that occur predominantly further offshore are likely underrepresented in this survey design. This survey approach and design is widely used in Alaska and elsewhere, providing comparable data that can be contrasted over various temporal and spatial scales.

Importance/Issues

Marine birds, particularly those that forage on benthic invertebrates, were selected as SWAN vital signs because of their reliance on habitats and prey associated with the marine nearshore ecosystem of park coastlines. These species are top level consumers of marine invertebrates such as mussels, clams, snails, limpets, and forage fish. Because of these characteristics marine birds are good indicators of change in the marine ecosystem. Monitoring focuses on birds that are trophically linked to the nearshore food web such as sea ducks, including harlequin ducks, (Histronicus histronicus), goldeneye and bufflehead (Bucephala sp.), long-tail ducks, (Clangula hyemalis), and scoters (Melanita sp.), several species of seabirds, and shorebirds, specifically the black oystercatcher (Haemoptopus bachmani). All observed marine birds are recorded.

Many of these focal species were impacted by the T/V Exxon Valdez oil spill and exhibited protracted recovery periods as a consequence of lingering oil in nearshore habitats. Public concern exists for the welfare of marine birds because they are affected by human activities like oil pollution and commercial fishing. Because mammals are encountered in the course of these surveys, observations of marine mammals are also recorded.

black oystercatcher foraging Kenai Fjords 2012
Male black oystercatcher foraging, Kenai Fjords National Park, 2012

Resource Brief - Black oystercatchers, 2013

Monitoring Reports

Protocol Documents

Subject YouTube Videos

Objective

  • Determine black oystercatcher nest density, nest occupancy rates, and size and species composition of prey brought back to the nest site to provision chicks among sites within a park, among different regions in the Gulf of Alaska, and among years

Sampling Design

Collection of black oystercatcher nest density/occupancy and diet data is collected annually along a 20-km transect centered on each randomly-selected intensive intertidal invertebrate and algal sample site. Identification of all nests within each transect allows estimation of nest density, and visits to all nest sites in subsequent years allows estimation of nest abandonment and establishment rates. Shell remains of prey captured and transported to the nest site to provision chicks are collected and used to estimate the species composition and size distributions of prey.

Importance/Issues

The black oystercatcher was selected as a SWAN marine nearshore vital sign because:

  1. It is a common and conspicuous member of the rocky and gravel intertidal communities along marine shorelines;
  2. It is completely dependent on nearshore marine habitats for all critical life history components including foraging, breeding, chick-rearing, and resting;
  3. It serves as "keystone" species that it important in structuring nearshore systems, largely as a consequence of its' preference for preying on species such as mussels and limpets;
  4. It is highly susceptible to human disturbance.

Because of their complete reliance on intertidal invertebrates as forage, the black oystercatcher provides a unique opportunity to view the nearshore zone from the perspective of an avian predator. The sampling also allows the use of the recognized relations between black oystercatchers and their prey to draw inferences between oystercatcher populations and their prey populations. Specifically, the long-term the sampling design will facilitate inferences relating density and productivity of oystercatchers to their diet (as reflected by prey brought to provision chicks) and to their prey populations.

coastal area Kenai Fjords
Coastline, Kenai Fjords National Park 2012

Resource Brief - Coastal Shoreline Change, 2011

Monitoring Reports

Shore Zone Mapping Protocol for the
Gulf of Alaska, 2004

Links to Partner Websites

For more information contact: Heather Coletti

Importance/Issues

Shoreline change was identified as a vital sign for the Southwest Alaska Network (SWAN) because land loss or gain at the marine edge has important ecological and jurisdictional implications. The physical configuration of the SWAN coastal shoreline is dynamic and constantly changing due to coastal erosion and accretion from natural events, such as storm-driven waves, high tides, nearshore currents, rainfall and runoff, landslides, and earthquakes. Changes in the position of the shoreline affect the composition, relative abundance, and distribution of coastal habitats.

Status and Trends

To evaluate the type of shoreline changes occurring along the 82 km coastline of Lake Clark National Park and Preserve, 7 of 10 cross-shore beach profiles established in 1992 were re-surveyed in 2004 using rod and transit leveling. Cross-shore beach profiles revealed variation in rates of erosion and accretion along the parks coastline. Erosion, landward migration of mean high water (MHW), was observed at 5 cross-shore profiles and accretion, seaward migration of MHW, was observed at 2 profiles. Annual average rates of erosion and accretion ranged from -0.18 to -0.50, and 0.55 to 3.13 m/yr respectively.

Current and Future Work Efforts

The availability of sufficiently high-resolution geospatial datasets, satellite imagery, and other remote sensing products now makes it possible to economically and comprehensively quantify shoreline change in space and time. In 2007, Dr. William Manley, Institute of Arctic and Alpine Research (INSTAAR), University of Colorado and the National Park Service selected three priority sites where long-term coastal shoreline change will the analyzed using aerial photography and satellite imagery in Lake Clark National Park and Preserve (1950s through 2006).

Annual rates of erosion and accretion at cross-shore beach profiles, Lake Clark National Park-Cook Inlet Coastline, 1992-2004.
Coastal change priority sites in SWAN
seastar katmai 2012
A seastar at low tide, Katmai National Park and Preserve 2012

Monitoring Reports

Subject Flickr Photo Galleries

Sampling Design

Water temperature is measured continuously throughout the year with Hobo data loggers at middle intertidal stations near long-term sheltered rocky sampling sites. Offshore water quality information will be provided by other programs, including AOOS, National Oceanic and Atmospheric Administration, Coastal Management Institute, and the Cook Inlet Regional Citizen Advisory Council.

Sampling Design: Contaminants

Since 2007, mussels have been collected at several intertidal sites in Kenai Fjords and Katmai for contaminant analysis. Mussel tissue was selected for examination because:

  • mussels tend to be integrators of contaminant loads and are likely to be less temporally variable than those measured in seawater and less spatially variable than those measured in sediments,
  • mussels are an important component of the nearshore food web and therefore provide a potential pathway of contamination to a variety of other nearshore species including sea ducks, sea stars, black oystercatchers, and sea otters, and
  • mussel tissue has been widely used in contaminant analysis in the Gulf of Alaska, elsewhere in the U.S. and the world, and these historical data provide a benchmark for examining temporal trends, making geographic comparisons, and evaluating potential environmental risks.

Importance/Issues

Marine Water Chemistry, including temperature and salinity, are critical to intertidal fauna and flora and are likely to be important determinants of both long-term and short-term fluctuations in the intertidal biotic community. Basic water quality parameters provide a record of environmental conditions at the time of sampling and are used in assessing the condition of biological assemblages.

Importance: Contaminants

High concentrations of contaminants, including polycyclic aromatic hydrocarbons (PAHs), organic pesticides, polychlorinated biphenyls (PCBs), and metals have long been recognized as having deleterious effects on nearshore communities worldwide. High concentrations are often the result of human activities such as oil spills, pesticide use, or mining activities. Their effects on nearshore organisms can range from acute (e.g. death caused by short term exposure to high concentrations) to those that are more subtle and longer-term (e.g. reductions in reproductive capacity or reductions in long term survival). Nearshore communities along the KEFJ and KATM have been subject to injury from oil spills (Spies et al. 1996) and are potentially threatened by a variety of human activities (future oil spills, mining, and inputs of airborne pollutants) and natural disturbances (e.g. earthquakes and volcanic eruptions).

harbor seal with pup on ice Kenai Fjords 2012
Harbor seal with pup, Kenai Fjords National Park, 2012

Status of Monitoring

Although observations of harbor seals in the water and on haul outs are included during the shoreline surveys of marine birds and mammals under the SWAN Nearshore Monitoring Project, this species is most amenable to survey methods that count seals systematically on traditional hauls outs during periods of low tide. The Polar Ecosystems Program (PEP) at the National Marine Fisheries Service-National Marine Mammal Laboratory (NMFS-NMML) conducts such aerial counts of harbor seal haulouts in each of five survey regions along Alaska's marine coastlines once every five years to monitor trends in seal distribution and abundance. SWAN reliesprimarily on these data for monitoring trends in harbor seals along Katmai, Kenai Fjords, and Lake Clark coastlines, supplemented by seasonal surveys of harbor seals conducted by the Alaska Sealife Center within Kenai Fjords.

Justification and Issues:

Harbor seals (Phoca vitulina) are one of the more common, conspicuous, and valued marine mammals that occupy nearshore habitats in the Gulf of Alaska. They are most frequently observed hauled-out on beaches or intertidal platforms during periods of low tide. Because they rely almost exclusively on marine and anadromous fishes as prey, they are generally recognized as occupying an upper trophic position in the nearshore forage fish based food web. They are also one of the preferred prey items of the transient, or mammal eating killer whale (Orcinus orca) type. Because they are thought to respond to changes in forage fish populations, they may serve as indicators of status and change within the marine nearshore forage fish based food web in the Gulf of Alaska. Harbor seals also are an important resource for Alaska Natives and for the tourism industry. Because this species has suffered serious declines in abundance across the Aleutian Archipelago, the Alaska Peninsula to Prince William Sound over the past several decades; populations in the Gulf of Alaska are of particular concern to management agencies.

Last Updated: November 14, 2014 Contact Webmaster