Website

Region(s)

SW

Summary

In southwest Florida, seagrass habitat maps interpreted from aerial imagery are of questionable accuracy. The Cape Romano area within the Ten Thousand Islands is known to have extensive submerged aquatic vegetation (SAV). This area has been mapped previously using high resolution aerial photography (Collier County Seagrass Protection Plan, 1991). The two main factors affecting the accuracy of these maps are water clarity and misinterpretation of unattached drift algae as seagrass. Slight changes in water depths and clarity can lead to significant differences in aerial photograph interpretation. The objective of this project was to map SAV distribution in a 2000 acre area within the Reserve using both high resolution aerial photography and side-scan sonar imagery and to compare the accuracy of the techniques. The accuracy of each technique for mapping the distribution and the density of SAV was assessed using underwater digital photography. The results indicate that the overall accuracy of the 100-400 kHz sonar and aerial imagery derived seagrass map and usefulness of each method to detect habitat change were not significantly different. Aerial imagery appears to be the most cost effective management tool to detect changes in seagrass habitat coverage of the Cape Romano Shoals area and similar areas with secchi depths greater than one meter. In areas with secchi depths of less than 0.5 meter the sonar imagery will be more useful. If other habitat features (propeller scars, hard substrate, worm tubes, sediment features) are important then sonar is the recommended imagery. Either mapping technique was estimated to have the ability to detect approximately 10-22% change in this seagrass habitat depending on oceanographic conditions.

Parameters

acreage (acres, hectares); seagrass presence or absence

Notes

Application

Publications

Start

2005

End

2005

Frequency

One-time

Method

side scan sonar and aerial photography

Discontinuity

Data Location

Cape Romano shoals

Data Format

shapefile

Habitats

Submerged Aquatic Vegetation

SEACAR Citation

Florida Department of Environmental Protection (DEP); Office of Resilience and Coastal Protection (RCP); Rookery Bay National Estuarine Research Reserve. (2005). A Comparison of Side-Scan Sonar and Aerial Photography for Submerged Aquatic Vegetation Mapping. Updated 04/22/2022. Distributed by: SEACAR Data Discovery Interface, Office of Resilience and Coastal Protection, Florida Department of Environmental Protection. https://data.florida-seacar.org/programs/details/5030

Alternative Citation

indicates priority attributes