because the cumulative impacts of actions within the system can have dramatic effects. For example, studies of the effects of development around lake shores on fish assemblages (Jennings et al., 1999) and habitat for northern pike and bluegill (Radomski and Goeman, 2001) have indicated the need to consider the cumulative effects of small habitat modifications. Although the effect of any individual protection measure on fish assemblages is difficult to identify during planning and permitting, or even post construction, the net effects of changes along the shoreline have been documented in many cases (e.g., Woodford and Meyer, 2003).

Cumulative effects may be an additive response to individual actions of the same type or the interactive consequence of multiple actions of different types (Spaling and Smit, 1993). Incorporating any potential cumulative effects of multiple actions into the planning process often requires a regulatory agency to look beyond issues within their own jurisdiction, as well as considering future, as yet unproposed, actions. Understanding the cumulative effects of shoreline protection measures within social, political, and ecological frameworks is an important component of an effective watershed or embayment plan. This provides a more holistic planning context that can reduce the unintended or unanticipated consequences of decision making on shoreline modification projects. In situations where insufficient information is available to provide an assessment of cumulative effects, a precautionary approach can be used to prevent irreversible loss of valuable habitats and other shoreline features (see Box 5-3).

• There is an incentive to install seawalls, bulkheads, and revetments on sheltered coastlines because these erosion control structures can be built landward