Eelgrass mapping of the Coos Estuary

 

Project Location: Coos Bay estuary, Oregon; The ocean entrance to the Coos estuary is at 43°21'13.37"N, 124°20'24.32"W (43.3537139, -124.3400889).

 

Background: The Coos estuary, located along the southern Oregon coast, encompasses 13,348 acres, making it the second largest estuary in the state. This large and complex estuary provides critical rearing habitat for dozens of marine and anadromous fishes and is home to many more resident fish and invertebrate species that spend their entire life cycle in estuarine habitats. Commercial fisheries are critical to the economy of the region, and the Coos estuary has been an important system in recovery planning for endangered salmonids and estuarine restoration. The proposed project requires data collection via aerial photography surveys over 20,902 acres, which includes fringing shoreline areas to ensure complete coverage of intertidal eelgrass habitat.

 

Purpose: Seagrasses provide important and preferred habitat for many marine and estuarine species, including 13 of the Pacific Marine and Estuarine Fish Habitat Partnership’s 15 focal species, yet comprehensive information on the distribution of seagrass habitat in the Coos estuary is lacking. The goal of this project is to create up-to-date geographic information system (GIS) data layers and associated maps that characterize the spatial extent of eelgrass (Zostera marina) throughout the entire Coos estuary. The only existing and publicly-available eelgrass data layers for the estuary were created from data collected in 2005 - consequently, the data are inadequate for supporting important projects such as habitat classification and conservation, mitigation and restoration planning, or ecological monitoring. The South Slough Reserve is also working closely with the Department of Land Conservation and Development (project partner) to refine and validate Oregon’s newly developed coast-wide estuary habitat classification system, referred to as the Coastal and Marine Ecological Classification Standard (CMECS). As applied to the Coos estuary, the CMECS system produced fairly coarse habitat classifications that do not provide the level of detail needed by Coos County for updating the Coos Bay Estuary Management Plan. This is in part because virtually no eelgrass data were included (or available) in the original coast-wide classification. The South Slough Reserve is working to systematically refine the CMECS for the Coos estuary and acquiring eelgrass data is imperative for this task. The Department of Land Conservation and Development is very interested in transferring our methods for this validation process (and our lessons learned) to future ground-truthing efforts in other estuaries. Thus, the results of this project will likely extend beyond the Coos estuary. Updated maps and data files on the spatial extent of eelgrass would also complement existing assessments of eelgrass function and susceptibility to stressors, including those associated with climate change. For example, the South Slough Reserve has been collecting data using standardized long-term monitoring protocols developed by SeagrassNet (http://www.seagrassnet.org/) to assess eelgrass bed dynamics at one location within the South Slough Reserve. Eelgrass monitoring is also included in the Reserve’s long-term biomonitoring program that measures the response of emergent marsh communities and eelgrass beds in South Slough to changes in sea level. These monitoring projects have supported a number of publications and unpublished technical reports (Rumrill 2006; Rumrill and Sowers 2008; Cornu et al. 2012; Cornu and Souder, 2015). The South Slough Reserve is also partnering with Oregon State University to evaluate the response of eelgrass beds to eutrophication at experimental locations within the Coos estuary and four other estuaries along the Oregon Coast. Additionally, through a PMEP-funded project, South Slough Reserve is conducting a spatial and temporal assessment of fish and invertebrate assemblages utilizing eelgrass habitat in the estuary. Since habitat conditions in one area of the estuary (e.g. South Slough) are not necessarily representative of the whole system, mapping data will help identify important locations for future work and comparative assessments. The proposed mapping data is also needed to determine the status of eelgrass in the estuary as a whole. By using similar methods to the 2005 survey, we will be able to assess changes in the spatial distribution and relative density of eelgrass beds over the past decade when the last comprehensive survey was conducted. In addition to using past methods, this project will also collect data on intertidal and subtidal eelgrass distribution and density at high tide along several transects in the project area. These surveys will be used to inform the aerial imagery to increase the accuracy and robustness of the resulting mapping files. The transect surveys also provide the added benefit of capturing detailed information on intertidal and subtidal eelgrass in priority areas to provide baseline data for monitoring projects.

Species that benefit: Pacific herring (Clupea pallasi), Dungeness crab (Cancer magister), English sole (Parophrys vetulus), Starry flounder (Platichthys stellatus), Shiner perch (Cymatogaster aggregata), Steelhead (Oncorhynchus mykiss), Coho salmon (Oncorhynchus kisutch), Chinook salmon (Oncorhynchus tshawytscha), Brown rockfish (Sebastes auriculatus),  Staghorn sculpin (Leptocottus armatus). In addition to the species identified above, the following species have been documented in the Coos estuary and would benefit directly or indirectly from this project: American shad, Arrow Goby, Bay Goby, Bay pipefish, Black Rockfish, Blennies, Blue Rockfish, Bocaccio, Brown Irish Lord, Buffalo sculpin, Cabezon, Chum salmon, C-O Turbot, Copper Rockfish, Crescent Gunnel, Curlfin Turbot, Cutthroat trout, Eulachon, High Cockscomb, Jacksmelt, Kelp Greenling, Large scale sucker, Lingcod, Longfin Smelt, Longnose dace, Mosshead sculpin, Northern anchovy, Pacific lamprey, Pacific Sablefish, Pacific Sand Lance, Pacific Sanddab, Pacific Tomcod, Padded Sculpin, Penpoint
Gunnel (green), Pile Perch, Pink Salmon, Plainfin midshipman, Prickly sculpin, Rainbow Perch, Red Irish Lord, Red Tailed Surf Perch, Redtail Perch, Rex Sole, Rock Greenling, Rock Sole, Rockweed Gunnel, Saddleback Gunnel, Sand Sole, Sardine Pacific, Sharpnose sculpin, Silver (surf) Perch, Silver spotted Sculpin, Snake Prickleback, Speckled dace, Speckled Sanddab, Striped bass, Striped Seaperch, Surf smelt, Threespine stickleback, Tidepool Sculpin, Tidepool Snailfish, Topsmelt, Tubenose poacher, Tube-snout, Walleye Perch, White Seaperch, Whitebait smelt

 

Evaluating success: This success of this project will be determined by its immediate deliverables, which include GIS shapefiles and maps showing eelgrass distribution in the estuary. These end products will be made publically available to project partners and natural resource managers and planners working in the Coos estuary. Long-term impacts and metrics of success will include reduced net impacts on eelgrass from dredging, development, and aquaculture activities due to mitigation and restoration activities and protection of eelgrass habitats.

 

Project partners: South Slough National Estuarine Research Reserve, Coos County Planning Department, Oregon Department of Land and Conservation Development

 

Climate change strategies addressed by this project:

3.2 Promote habitat connectivity and integrity.
3.3 Reduce non-climate change ecosystem stressors.

3.5 Conserve coastal and marine resources.

 

National Conservation Strategies address by this project:

1. Protect intact and healthy waters.

3. Reconnect fragmented fish habitats.