Whatcom County MRC Projects -
Submerged Aquatic Vegetation (SAV) Survey

Submerged aquatic vegetation is used as an indicator of estuary health throughout the world because it responds to many natural and human caused environmental variables. Changes in abundance or distribution of this resource are likely to affect other species that depend on this habitat. For example, SAV function as rearing and forage habitat for juvenile salmonids and Dungeness crab. In addition, Pacific herring use eelgrass beds and macroalgae in Whatcom County for spawning. Larval herring, surf smelt, and sand lance, as well as invertebrate organisms that are prey items for juvenile salmon, also use this habitat. As a part of local efforts to collect baseline information and prioritize nearshore restoration and conservation projects, the MRC surveyed SAV from the north end of the Lummi Reservation to Point Whitehorn.


Survey Methods

SAV has been assessed at many locations in Whatcom County using a variety of methods. These assessments range from efforts to comprehensively map the nearshore vegetation over a large area to intensively mapping a very narrow study area. Survey methods that have been used include physical, off-water remote, and on-water remote. The advantages and limitations of each of these methods are described in the Survey Methods report. The methods that were selected for this survey were a combination of a beach walk with a GPS unit and underwater videography and hydroacoustic soner interfaced with a GPS unit.

Whatcom County Submerged Aquatic Vegetation Survey Methods


What Was Surveyed?

Vegetation
The vegetation types included in this survey were:

Vegetation Density

  • Absent: 0% plant cover
  • Low: 1%-50% plant cover
  • High: 51%-100% plant cover

Substrate

  • Rock, hardpan (>256 mm)
  • Cobble (64-256mm)
  • Mixed Coarse (38-304 mm)
  • Gravel (4-64mm)
  • Sand (0.06-4mm)
  • Mixed fines (unwashed sand and mud with some gravel and organic matter)
  • Mud (<0.06 mm)


Survey Findings

Three maps were generated illustrating the surveyed attributes.

  • Map 1 depicts the surveyed turf and canopy algae. This data is represented as polygons.
  • Map 2 depicts the surveyed eelgrass, bull kelp, and sargassum. This data is represented as polygons.
  • Map 3 depicts the surveyed substrate. This data is shown as line data where collected by the beach walk and point data along transects where collected by boat survey.

Table 1. Area SAV coverage observed at Cherry Point in August, 2004
This table describes the area of each vegetation classification through the survey zone in both square feet and square meters.

  LOW DENSITY
(SQ FT)
 HIGH DENSITY
(SQ FT)
 LOW DENSITY
(SQ METERS)
 HIGH DENSITY
(SQ METERS)
Turf Algae
1,894,772.2
1,615,010.8
176,024.3
150,034.5
Canopy Algae
3,142,068.7
1,271,794.0
291,898.2
118,149.7
Bull kelp
2,329,223.2
0.0
216,384.8
0.0
Sargassum
2,089,646.6
0.0
194,128.2
0.0
Eelgrass
2,736,898.9
102,639.6
254,257.9
9,535.2

 

More details about the survey, findings, and cost-effectiveness of this survey method are included in the final report.

Whatcom County Submerged Aquatic Vegetation Survey Final Report