Chapter 7: Monitoring Rehabilitation in Temperate North American Estuaries
Casimir A. Rice, W. Gregory Hood, Lucinda M. Tear, Charles A. Simenstad, Gregory D. Williams, Lyndal L. Johnson, Blake E. Feist, and Philip Roni
At the seaward end of the watershed continuum, estuaries are rich and highly productive ecosystems, critically important to many living aquatic resources (Day et al. 1989; Knox 2001), yet are also among the environments most heavily altered by human activity (NOAA 1990; Tibbet 2002; POC 2003; USCOP 2004). Because of human population growth and continued decline in estuarine ecosystem abundance and quality, the pressure on estuarine resources continues to increase. Consequently, estuaries are a growing focus of habitat rehabilitation through restoration, enhancement, and creation (Thayer 1992; Restore America’s Estuaries 2002; Thayer et al. 2003). Unfortunately, these projects are rarely evaluated effectively (NRC 1990, 1992, 2001; Wilbur et al. 2000). In this chapter, we propose that monitoring rehabilitation in estuarine ecosystems requires quantifying relationships between dynamic estuarine processes and sensitive indicators of ecosystem function. While we discuss temperate systems in general, we emphasize anadromous salmon (Oncorhynchus spp.) habitats in the Pacific Northwest because anadromous fishes are a major focus of rehabilitation efforts and present some of the greater challenges in linking functions of one segment of their life history to conditions in a specific habitat. We begin with a review of human impacts on estuaries, the estuarine environment, salmonid use of estuaries, and common estuarine rehabilitation techniques. Next, we discuss considerations in designing monitoring and evaluation programs for estuarine rehabilitation projects, including conceptual models, key questions, scale, study design, sampling strategies, reference materials, and timing and duration. We then discuss selection and measurement of physical, biological, and chemical parameters. Finally, we summarize the key considerations, challenges of estuarine monitoring, and additional information and research needs.