2: Account for ecosystem connectivity

When we think about our own health, we focus on all parts at the same time. Eating well is as important as exercising, which is just as important as getting enough sleep and stimulating our minds. We need do the same and think about all the parts when we design a healthy ecosystem too.

Ecosystems like the Salish Sea are connected to many places by animals like the gray whale as well as by things like commerce and economics. We need to pay attention to these connections. Photo: J. Mazet

Ecosystems are more interconnected than most people appreciate. Citizens, scientists, managers and policy makers filter out these connections in order to focus on specific areas or species of interest, using compartmentalization to simplify the daunting challenges of managing complex systems. 

Understanding the connectivity and linkages between seemingly unrelated species and ecosystems is key to successful restoration. Like most ecosystems, the factors determining the fate of the Salish Sea extend hundreds of kilometers from the sea to the crest of the mountains that surround these waters. For example, the amount and configuration of impervious surfaces (e.g. concrete parking lots, roads) and harvested forests impact the biotic integrity of streams feeding into the Salish Sea, which in turn affects the health of the entire ecosystem.

Forest health impacts the abundance of the marbled murrelet, an endangered seabird that nests up to 50 miles inland in old growth forests, but spends the remaining 11.5 months of the year feeding at sea.

Intricate food webs can connect species across ecosystems. For example, gray whale abundance is linked to productivity in the Bering Sea and the abundance of migrating gray whales feeding in the Salish Sea could be important for the recovery of declining surf scoter populations.

Commerce and transportation are powerful non-biological forces that link the biota of Puget Sound to other ecosystems. For instance, in 2006-2007 Washington State and tribal fishermen harvested over 225 metric tons of sea cucumbers, the majority of which were exported to Asian markets. Increasing non-local demand for fisheries can potentially drive unsustainable harvest and hinder restoration. The robust shipping industry that links the Salish Sea to most of the world also is a source of invasive species that can threaten the integrity of biological communities.

Connectivity contributes to ecosystem functions and understanding these intricacies is important for designing healthy ecosystems. For example, recent modeling suggests that the mangrove-based ontogenetic migrations of parrotfish could, through a trophic cascade on macroalgae, enhance the recovery rate of midshelf Caribbean coral reefs from hurricanes. Consequently preserving or replanting mangroves will improve Caribbean coral resiliency in the face of predicted increased hurricane frequency and intensity.

While it is tempting to filter out the apparent “noise” from other species and ecosystems, acknowledging and identifying key cross-species and cross-habitat connections are essential to understanding changes in the system and measuring performance.