Getting Strategic about Freshwater Biodiversity Conservation in California

Pacific giant salamander (Dicamptodon ensatus) – The Pacific giant salamander is the largest terrestrial salamander in North America and is one of several salamanders that have vocal abilities.

by Jeanette Howard, Kurt Fesenmyer, Theodore Grantham, Joshua Viers, Peter Ode, Peter Moyle, Sarah Kupferberg, Joseph Furnish, Andrew Rehn, Joseph Slusark, Raphael Mazor, Nicholas Santos, Ryan Peek, and Amber Wright

An essential first step to protect biodiversity is understanding what species are present in a region, where they can be found, and their conservation status. For freshwater organisms in California, this information has been difficult to gather because sampling data are collected by many different entities and have been stored in disparate databases.

But now, a large number of freshwater biodiversity datasets have been assembled to guide strategic conservation planning for the numerous plants and animals that find a home in the state’s rivers, lakes, ponds, and wetlands. “Big Data” has arrived in the form of the PISCES database, which includes range information for all of California’s freshwater fishes; open access to global biodiversity museum records; eBird and other citizen science data collections; and the aggregation of local freshwater bioassessments into the Surface Water Ambient Monitoring Program (SWAMP) database.

To provide a comprehensive inventory of freshwater dependent species, these and other datasets have been compiled into a statewide repository. A new California Freshwater Species Database contains information on 3,906 vertebrates, macroinvertebrates, and vascular plants native to California and that depend on fresh water for at least one stage of their life history. This database has enabled a better understanding of the patterns of freshwater species richness, endemism, and vulnerability in California. The database also provides the foundation for a statewide Freshwater Conservation Blueprint, which for the first time systematically identifies priority watersheds for native freshwater biodiversity management and conservation across California.

Conservation Planning – Putting the Information to Work

Western pearlshell mussel (Margaritifera falcata) – The western pearlshell mussel have life spans up to 100 years and depend on fish hosts for larval development.

Although the loss of terrestrial biodiversity garners much attention, freshwater species are at the forefront of the global extinction crisis. Species dependent on freshwater habitats are in decline globally (Dudgeon et al. 2006) with between 10,000 and 20,000 freshwater species thought to be extinct or imperiled. In California, nearly half of the state’s native freshwater taxa and 90% of the state’s endemic taxa are vulnerable to extinction, with 11 freshwater species considered extinct (1 plant, 2 crustaceans, 1 mollusk, 1 frog, 6 fishes) and 14 possibly extinct (8 insects, 2 amphibians, 1 turtle, 1 mollusk, 2 plants). Moreover, estimates of extinction rates are considered underestimates because freshwater organisms are understudied (Abell 2002).

 Scientists have long been aware that conservation of freshwater biodiversity faces severe challenges. The fragmented nature of freshwater habitats often results in high levels of endemism, making freshwater populations highly vulnerable to extirpation (Strayer and Dudgeon 2010). In addition, efforts to conserve freshwater species are often stymied because protected areas typically reflect jurisdictional/landscape boundaries that have little meaning for aquatic species. For example, an assessment of conservation priority areas for California’s freshwater fishes found that there was little overlap with the state’s existing protected area network (Grantham et al. 2016),  indicating that improved management of both private and public lands is needed to conserve native fish species.

Pacific tree frog (Pseudacris regilla) has a remarkable wide geographic range from Baja to southern British Columbia and inland to parts of Idaho, Nevada and western Montana. This frog is so adaptive that you can find them in your backyard, along the beach, in the Mojave Desert, grasslands and even at 11,000 feet on Mount Whitney.

Efforts to protect freshwater species are often stymied because protected areas typically reflect jurisdictional/landscape boundaries that have little meaning for aquatic species. For example, an assessment of conservation priority areas for California’s freshwater fishes found that there was little overlap with the state’s existing protected area network (Grantham et al. 2016),  indicating that improved management of both private and public lands is needed to conserve native fish species.

Grantham et al.’s effort has recently been expanded to identify watersheds of high conservation value for a broader range of freshwater species. Led by Jeanette Howard of The Nature Conservancy in collaboration with scientists from the state, federal, academic, and NGO community, we used a conservation planning tool to identify an efficient network of priority conservation watersheds for California’s fishes, frogs, salamanders, snakes, and turtles – the ‘target taxa’. The planning tool first identifies watersheds where the majority of land area or perennial stream mileage has a management mandate emphasizing biodiversity – ‘existing protected areas’ such as national parks – and then incorporates a network of additional watersheds where the most taxa co-occur and where rare taxa are present.

Priority conservation areas. The network is comprised of watersheds with a fish, amphibian or reptile target species present and at least 75% of the watershed area or stream network in a protected area (USGS Gap Analysis Program status 1, 2; green watersheds), and watersheds that best complement these protected areas based on species present (purple watersheds). The network is constructed in a way that maximizes the number of species and proportion of those species’ ranges included, while minimizing the area of the network.

The assessment was recently published in an article in Freshwater Science (Howard et al. 2018) and outlines a Freshwater Conservation Blueprint for California. The Blueprint delineates a comprehensive, representative, and efficient freshwater conservation network that covers around 1/3 of the land area of California (Figure 1) – yet includes at least 10% of the range of all target taxa.  This area is comparable in size to existing protected areas, but provides more “bang for the buck” in conserving freshwater biodiversity because many target taxa are absent from existing protected areas.

More importantly, ~70% of the freshwater conservation network occurs on public lands managed for multiple purposes such as grazing, logging, and recreation.  These lands are largely those of the US Forest Service and Bureau of Land Management, where small changes in management could provide substantial benefits to freshwater biodiversity.

The Blueprint provides strong evidence for compatible management of aquatic biodiversity on multi-use public and private lands. Maps of priority conservation areas are available online via California Department of Fish and Wildlife’s BIOS tool, and we have developed an online decision support tool for evaluating impairments, threats, and potential conservation actions within the priority areas.

How This Blueprint Can Be Used

The goals of the Freshwater Blueprint for California are to help improve the efficiency of on-going and planned conservation efforts and accelerate progress towards effective, long-term preservation of the state’s freshwater biodiversity.

Longhorn fairy shrimp (Branchinecta longiantenna) – an federally listed endemic crustacean to California where there are only four known populations.

The proposed conservation network is intended to identify watersheds where management actions can be prioritized to conserve native freshwater biodiversity. We don’t envision the state establishing a new reserve network – rather, the objective is to create a more coherent and targeted approach to freshwater conservation.

Limited resources require strategic action to conserve freshwater taxa currently represented within protected areas and to preserve biodiversity hotspots that primarily occur outside reserve boundaries. Because priority catchments within and outside protected areas are threatened by climate change and other stressors, conservation will require reconciliation approaches to create the best possible conditions for freshwater fishes in altered environments within existing management regimes (Moyle 2013).

There is growing evidence that conservation of freshwater biodiversity is compatible with human uses. For example, efforts to restore flows in Putah Creek via dam releases and the Shasta River through changes in agricultural irrigation practices have resulted in improved conditions for native fishes without adversely affecting primary human uses. Restoring floodplain connectivity in human-dominated landscapes through managed floodways, offseason flooding of fields, or active levee breaching, have been shown to provide multiple ecosystem benefits, reduce flood risk, and sustain floodplain agriculture. By guiding the strategic implementation of such management approaches, the Freshwater Conservation Blueprint can help bring ecosystem reconciliation to scale and ensure the long-term preservation of the state’s freshwater biodiversity.

We emphasize that while the Blueprint lays the broad groundwork for a conservation strategy, it is not meant to diminish more localized conservation efforts that are outside the designated areas.  All the species covered by the Blueprint need multiple populations to thrive. Thus, smaller refuges outside those designated in the Blueprint are always important.  This is one reason why statewide monitoring programs are needed to continually expand and update the database to track the changes in the range and abundance of freshwater species. With good data and a strategic approach, we can reverse the trends of biodiversity loss and safeguard the future of our state’s freshwater species.

Jeanette Howard is the Director of Science for the Water Program at the Nature Conservancy. Kurt Fesenmyer is the GIS and Conservation Planning Director with Trout Unlimited. Ted Grantham is faculty at the University of California, Berkeley, and an affiliate of the U.C. Davis Center for Watershed Sciences. Josh Viers is faculty at the University of California, Merced, and an affiliate of the Center for Watershed Sciences. Peter Ode is affiliated with the Aquatic Bioassessment Laboratory at the California Department of Fish and Wildlife. Peter Moyle, Nicholas Santos, and Ryan Peek are affiliates of the Center for Watershed Sciences. Sarah Kupferburg is with Questa Engineering. Andrew Rehn and Joseph Slusark are affiliates of the Aquatic Bioassessment Laboratory, California Department of Fish and Wildlife, and Center for Water and the Environment—California State University, Chico. Raphael Mazor is affiliated with the Southern California Coastal Water Research Project. Amber Wright is faculty at the University of Hawaii, Manoa.

Further reading

Howard JK, et al. 2018. A freshwater conservation blueprint for California: prioritizing watersheds for freshwater biodiversity. Freshwater Science. 37(2):417-31.

Strayer DL, Dudgeon D. 2010. Freshwater biodiversity conservation: recent progress and future challenges. Journal of the North American Benthological Society. 2010; 29: 344–358.

Dudgeon D et al. 2006. Freshwater biodiversity: importance, threats, status and conservation challenges. Biological Reviews. 81: 163–182.

Abell R. 2002. Conservation biology for the biodiversity crisis: a freshwater follow-up. Conservation Biology. 16(5): 1435–1437.

Grantham, TE, et al.  2017. Missing the Boat on Freshwater Fish Conservation in California. Conservation Letters. 10: 77-85.

Howard JK, et al. 2015. Patterns of Freshwater Species Richness, Endemism, and Vulnerability in California. PLoS ONE. 2015; 10(7): e0130710.

Moyle, P.B. (2013). Novel aquatic ecosystems: the new reality for streams in California and other Mediterranean climate regions. River Res. Appl., 30, 1335-1344.

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