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Determining bathymetric distributions of the eelgrass Zostera marina L. in three turbid estuaries of the eastern North Pacific coast
Citation:
YOUNG, D., P. J. CLINTON, D. T. SPECHT, T. MOCHON COLLURA, AND H. LEE, II. Determining bathymetric distributions of the eelgrass Zostera marina L. in three turbid estuaries of the eastern North Pacific coast. BOTANICA MARINA. Walter de Gruyter GmbH, Berlin, Germany, 55:229-240, (2012).
Impact/Purpose:
Improved methods for determining bathymetric distributions of dominant intertidal plants throughout their estuarine range are needed.
Description:
Improved methods for determining bathymetric distributions of dominant intertidal plants throughout their estuarine range are needed. Zostera marina is a seagrass native to estuaries of the northeastern Pacific and many other sectors of the world ocean. The technique described here employed large format aerial photography using false color near-infrared film with digital image classification, and the production of digital bathymetric models of shallow estuaries such as those occurring in turbid waters of the Pacific Northwest USA. Application of geographic information system procedures to the eelgrass classifications and bathymetry distributions yielded digital bathymetric distributions based upon a very large number of observations. Similar bathymetric patterns were obtained for the three estuaries surveyed, and approximately 90% of the classified eelgrass occurred within the depth range -1.0 m to +1.0 m (MLLW). Comparison of these distributions with ground surveys of eelgrass lower depth limits indicated that the area of undetected subtidal eelgrass constituted < 10% of the areal distributions classified (with > 86% overall accuracy) in each estuary. The pattern of eelgrass in one estuary was distinctly different from those in the other two systems, illustrating the potential usefulness of this technique in exploring causative factors for such differences in estuarine intertidal vegetation distributions.
