Willapa Bay was selected for use as a demonstration community to illustrate the Community Explorer module. This region, located in southwestern Washington State, was selected because of its active NatureMapping community and the availability of digital data, most of which was acquired with permission from the Willapa Watershed Information System CD (Ecotrust**).

Exploring Willapa Bay
The Willapa Bay Watershed, located just north of the Columbia River, was named in a recent federal study as the most productive estuary remaining in the lower 48 states. Including the bay, the Willapa watershed contains approximately 680,000 acres. The region is heavily forested with Douglas-fir, western hemlock, western red cedar and Sitka spruce. In fact, the Willapa Watershed once held some of the most massive trees encountered anywhere in the world.

Willapa Bay is as prolific as the lands surrounding it. Its tidal flats contain one quarter of the productive shellfish waters of the western United States while its native eelgrass beds and marshlands provide critical habitat for over seventy species of migratory birds.

Willapa's 19,000 year-round residents depend on livelihoods rooted in the natural resources. Nearly two-thirds of the land is commercial forestland. Farms and irrigated lands together make up another seven percent, clustering on the valley bottoms where the majority of the small landowners reside. Washington Department of Natural Resources and the US Department of the Interior comprise the last major landholders in the region.

In the Bay, shellfish are a major economic contributor. Oysters are cultivated on over 10,000 acres of privately owned or leased tidelands, Clams and crabs are also harvested commercially and for sport.

NON-NATIVE AQUATIC SPECIES

Non-natives in Willapa Bay
Because of their importance to the Willapa Community, this demonstration project uses three non-native aquatic species to illustrate how Community Explorer will work: the bullfrog, the European green crab, and a tidal marsh grass known as Spartina alterniflora.

What are Non-native Aquatic Species?
A "native" species lives within its natural or historic range and zone of natural dispersal. Non-native aquatic species are initially introduced by human activities into freshwater, brackish or marine ecosystems where they could not go naturally (by swimming or floating on winds, tides or currents).

Why are Non-native Aquatic Species a Problem?
Non-native species — also called exotic, nonindigenous or alien species — can alter or degrade native habitat. They may prey on native species or outperform them in the quest for food, space and other resources, sometimes even causing the extinction of native species. Once established, exotics can rarely be eradicated.

Pathways for Non-native Aquatic Species
Humans have dramatically increased the scale and scope of invasions by non-native species. Each of these three species is an example of how human activities can result in the spread of non-native species. Because of their meaty legs, bullfrogs were originally introduced from the eastern US to be raised for food ; green crabs most likely were deposited from ballast water from east coast or Japanese ships ; and Spartina was used as a packing material for shipping oysters from the east coast.

Willapa Bay Community Explorer
The bullfrog, green crab and Spartina all have unique ecological requirements, vectors of transport and varying information regarding their distribution and impacts to native species and processes. Community Explorer will help to identify spatial relationships and patterns between these species, the environment and human beings.

This information is used by permission from Handling & Disposal of Non-native Aquatic Species and their Packaging, a brochure published by Washington Sea Grant Program, University of Washington.

BULLFROG BACKGROUND

Why are Bullfrogs a Problem?
Bullfrogs (Rana catesbeiana) are extremely opportunistic carnivores. Their diet includes a wide variety of both invertebrates (insects, earthworms, etc.) and vertebrates (fish, tadpoles, frogs, salamanders, snakes, small turtles, birds and small mammals).

Due to their voracious appetite, bullfrogs have negatively impacted native aquatic species, particularly the Spotted Frog and the Western Pond Turtle. In addition, biologists have noted declines in waterfowl populations corresponding with the spread of bullfrogs at the Columbia National Wildlife Refuge.

How did the Bullfrog get Here?
The bullfrog was introduced to the Pacific Northwest from the eastern US in the 1920’s or 1930’s to be raised for food. Ongoing range expansion in Washington State is speculated to be due more to illegal pet releases and floral nursery sales for insect control than the species’ ability to spread on its own. As such, they are often found in populated areas, where the likelihood of release is greatest.

Where are Bullfrogs Likely to be Found?
Examine the census tract information. Where are the high population areas? If people are indeed responsible for the species’ ongoing range expansion, where would you expect to see bullfrog records in the Willapa area?

Check your assumptions.

Let’s zoom in to an area for a closer look. Upon closer examination, the bullfrog records lie just outside the high population areas. Can you think of why this would be?

Habitat Requirements
In addition to a pathway of introduction, species’ need adequate habitat to survive. Because the bullfrog seldom ventures far from permanent water (including ponds, lakes, reservoirs, sluggish irrigation ditches and slow-moving streams and rivers), let’s evaluate permanent water bodies in close proximity to this record. The light blue depicts permanent open water. The bullfrog record is located on the edge of the lake nearest to the high population area.

Knowing the bullfrog prefers warmer waters, what sort of vegetation would you expect to see where the record was taken? The non-forested canopy cover found where the record was taken may help water on the west side of the lake reach the higher temperatures bullfrogs prefer than those waters fully shaded on the east side of the lake.

Need for More Data
As you saw, only four bullfrog sitings are on record for the Willapa region. Undoubtedly, there are far more bullfrogs in the area then these records reflect. Although bullfrogs have been "established" residents of the Pacific Northwest for almost 80 years, very little data have been collected regarding range and expansion patterns.

Information submitted by NatureMapping participants will be incorporated into the statewide NatureMapping database. This database allows NatureMappers, biologists and natural resource managers to use GIS to get detailed information for any record simply by clicking on the point.

SPARTINA BACKGROUND

Why is Spartina a Problem?
In 1995, the Washington State Legislature declared the spread of Spartina "an environmental disaster." With over $1 million spent every two years for Willapa Bay control efforts alone, the rate of expansion still far outpaces the rate of control.

Spartina alterniflora, also known as smooth cordgrass, is considered the foundation of estuarine food webs in tidal marshes along the Gulf of Mexico and the east coast of the United States. On the west coast, however, Spartina is considered a noxious weed.

Spartina grows in dense stands that decrease water velocities and increase deposition of fine sediment and organic matter (accretion). Sediment accretion accelerated by colonizing Spartina can rapidly transform unvegetated littoral flats into monotypic Spartina marshes. This expansion may facilitate and accelerate expansion by native marsh plants, thus accelerating the normal successional processes found in estuaries.

How did Spartina get Here?
Oyster growers unintentionally introduced Spartina in the 1890’s when it was used as a packing material for shipping oysters from the east coast. Although Spartina established itself in Willapa Bay soon thereafter, it was not until the 1950’s that concern was great enough to evaluate impacts to the estuary. At that time there were approximately 400 acres of Spartina.

In 1999, state and federal agencies estimated Spartina covered anywhere from 5,000 to 25,000 acres of the Willapa estuary. Estimates vary widely depending upon the density of Spartina that is considered a patch or area. For example, the total area of Spartina meadows in Willapa Bay is considerably less than the total area considered "infested" with Spartina. This is because "infested" can be defined as anything from a few Spartina shoots per acre to a dense Spartina meadow.

Where is Spartina Likely to be Found?
Spartina typically grows at elevations from +1 to +2 m re. Mean lower low water (MLLW) in Willapa Bay. With the ability to excrete unneeded salt on the plant’s leaf edges, Spartina survives in areas flooded by brackish water (mean salinity in Willapa Bay is around 25 ppt), growing primarily along marsh creeks and in places flooded by tidal waters.

Spartina is sensitive to the forces imposed by wave action and, compared with the exposed Pacific Coast, Willapa Bay offers the plant some refuge with its relatively lower wave energy (maximum wave height is around 2 m). Regardless, those areas in Willapa Bay with the greatest potential wave energy* tend to have less Spartina.

* Wave energy data was used with permission from Blake Feist, and was originally created for his dissertation published by the University of Washington, Seattle.

Given the above preferred environmental parameters, where would you expect to find Spartina in Willapa Bay? Were your predictions correct?

Habitat Requirements
Spartina reproduces occasionally via seed, but primarily via vegetative expansion through underground roots called rhizomes. Once established, clones grow quickly, approximately 75 cm in radius each year. Clones grow larger until they coalesce with other clones and create large ‘meadows’, often fronting native marshes.

At this scale, it appears as though the Spartina meadows are fairly homogeneous. Let’s zoom in a little closer to make sure. When we take a closer look, we see that what appeared to be solid polygons actually contain many smaller polygons impossible to see at the previous scale. These meadows actually contain Spartina beds ranging in density from less then 5% to greater then 75% coverage. It is important to keep map scale in mind when drawing conclusions at a glance.

Economic Ramifications
In addition to altering natural processes, there is concern that Spartina may also impact Willapa Bay’s local economy. The potential influence of Spartina expansion on the oyster culture industry is one of the greatest concerns. Oysters are big business in the Willapa economy. With over 10,000 acres of cultivated oyster beds, one of every 6 oysters consumed in the US is harvested from Willapa’s tide flats.

Let’s use GIS to help us evaluate the relationship between Spartina and Willapa Bay’s oyster beds. Reflecting on earlier lessons, why do you think the two overlap? If you guessed tide flats were the link, you were right. Both Spartina and oysters thrive on the mud flats of Willapa Bay.

Spartina’s ability to trap sediment and transform littoral flats into marsh is causing concern that oyster beds are increasingly threatened by Spartina’s continuing expansion. The shift from littoral flats to marsh may reduce the total habitat area available for growing oysters.

So far we have simply overlaid data layers to help us understand patterns between species and their environment. Using GIS, we can intersect the Spartina and the oyster bed layers to identify where each exists alone and where they overlap.

Let’s zoom in to the area of oyster beds heavily impacted by Spartina. Because oyster bed quality was recorded along with location, we can look to see how different types of oyster beds are affected by Spartina’s presence. What patterns do you see? Zooming out to the Bay in its entirety, do you see the same patterns?

So far, it appears as though the "good" quality oyster beds are little affected by Spartina. This is probably because oysters "prefer" deeper water habitats (usually 1 m deeper) than Spartina does. To see this more clearly, draw the data layer containing only "good" quality oyster beds.

To make sure our visual conclusions are correct, we can use GIS to run some calculations. When oyster beds are intersected with the Spartina coverage we have a total of 33,849 acres. Only 3,528 of those acres contain both Spartina and oyster beds. That leaves 25,481 acres of oyster beds unaffected by Spartina and 4,839 acres of Spartina growing where no oyster beds exist. For a better picture of this relationship this chart breaks down the percentage of Spartina found in each oyster bed class.

GREEN CRAB BACKGROUND

Why are Green Crabs a Problem?
The European green crab (Carcinus maenas) is a recently introduced species in Washington and, where it is found, it appears to be rapidly out-competing native crabs. This voracious eater consumes clams, oysters, mussels, small crabs and young Dungeness crabs. Sampling records from California’s Bodega Bay show significant reductions in clam and native shore crab population abundance since the arrival of the green crab in 1993.

Washington State Department of Fish and Wildlife warns that if the green crab becomes established in Washington waters, it poses a significant threat to the state’s clam and oyster-growing industries as well as the commercially important Dungeness crab fishery. The Agency warns that commercial shellfish growers may have to change their culture methods to reduce losses from predation if a green crab population establishes itself in Washington State.

How did Green Crabs get Here?
The European green crab is a small shore crab whose native distribution spans the Atlantic coasts of Europe and northern Africa from Norway south to Mauritania. While the first sightings in the United States were on the East Coast, it was reported in San Francisco Bay in 1989. Since then, it has moved north to Oregon and Washington State, including Willapa Bay and Grays Harbor.

It is not known how the European green crab was first introduced, although ballast water from ships arriving from the Atlantic or Japan seems the most likely avenue. The subsequent migration north along the west coast is most likely the result of ocean currents transporting green crab larvae or via additional ballast water introductions.

Where are Green Crabs Likely to be Found?
Habitat preferences include protected rocky shores, cobble beaches, and sand flats. Rarely found along wave exposed areas of the intertidal, the green crab prefers sandy, muddy substratum of quiet bays and estuaries. Given these parameters, where would you expect to find the green crab?

Link to Spartina
It is speculated that the green crab is closely linked with the occurrence of Spartina. An evaluation of green crab food sources identified Spartina as one of their preferred foods and has proven to be good habitat in Willapa Bay in which to successfully trap green crabs. In fact, of the 29 records available for green crabs in Willapa Bay, 21 note proximity to Spartina (highlighted in yellow).

Using Data with a Critical Eye
Let’s take a closer look at an area where Spartina and green crab records coincide. Remember, the crabs recorded in or near Spartina are highlighted in yellow. Upon examination, this map shows apparently contradictory information. The only record that was identified as not being associated with Spartina lies in the middle of a Spartina polygon. Can you think of why this might be?

By looking at the Spartina theme’s legend, or looking at the data underlying the polygon, note that the polygon delineates an area with only 5% of its area covered with Spartina. Even though this green crab record lies within a ‘Spartina polygon’, it falls in an area devoid of Spartina.

Conversely, where observers have recorded green crabs located within Spartina patches, no Spartina polygon appears in our spatial dataset. Can you think of possible explanations?

Observer error in recording information could be one possibility. The green crab location may have been recorded incorrectly so the data point falls in the wrong location.

Another possibility is that the Spartina spatial dataset is incomplete. Spartina may have been present when the coverage was developed, but was overlooked and therefore not mapped. It is also possible that it was not present in that location in 1992/1993 when the Spartina dataset was developed, but had spread to that location by the late 1990’s when the green crab sighting was recorded.

All of these scenarios demonstrate the diligence required of the users of spatial data. When the data was collected, how and by whom it was collected and the scale at which it was collected all impact how it can be assessed, particularly when evaluating it in conjunction with multiple datasets.

Information Gaps
In addition to inaccurate or incomplete datasets, biological uncertainties also inhibit proactive attempts to predict range expansions of non-native species. The green crab, like many invasive species, may respond differently to non-native environments than they would to their native habitats. Currently, little information is available for how the green crab has adapted to living in Willapa Bay. Researchers are still trying to identify where the green crabs are, which traps are the best to use and where to place them.

Without data to support their claims, the media is reporting there may be more than $45 million in damage because these crabs will decimate the state’s shellfish and other crab populations. In an effort to learn more about potential green crab impacts, workshops for volunteers to aid in green crab identification are already underway. These workshops are being sponsored by various agencies, including Washington Sea Grant, US Fish and Wildlife Service and Washington State Department of Fish and Wildlife.