All Hail The King… Tides, That Is

If you’ve been watching the news, you’ve probably heard some mention of King Tides in places like Sausalito, Mill Valley, San Francisco, and Alameda. A King Tide is no farcical aquatic ceremony, but it is one of the highest high tides of the year. A King Tide is a natural phenomenon that occurs near the Summer and Winter solstices, during the new and full moon phases, when the moon, sun, and Earth are aligned. This alignment causes the strongest biannual gravitational force on Earth’s oceans, resulting in these dramatic tidal fluctuations.

Figure 1. Earth’s tides and the contributing gravitational factors
Figure 1. Earth’s tides and the contributing gravitational factors.

King Tides help us to see today what will be the average daily high tides in 2050 and they show us now where flooding will occur as the sea level continues to rise as shown in the photos below. These photos were submitted to the California King Tides Project, which encourages people to take pictures of their communities to document flooding during King Tides.

Photos a-f. Photos submitted to the California King Tides Project of San Francisco Bay Area communities during a King Tide in Winter 2012/2013. (a) The Embarcadero in San Francisco (b) Sidewalk in Alameda (c) HWY 1 underpass in Sausalito (d) Byway in Mill Valley (e) Sharp Park in Pacifica, (f) Rockaway in Pacifica
Photos a-f. Photos submitted to the California King Tides Project of San Francisco Bay Area communities during a King Tide in Winter 2012/2013. (a) The Embarcadero in San Francisco (b) Sidewalk in Alameda (c) HWY 1 underpass in Sausalito (d) Byway in Mill Valley (e) Sharp Park in Pacifica, (f) Rockaway in Pacifica

Tide gauge measurements can tell us about past and present sea levels —  The sea level in San Francisco Bay has risen about 4 inches since the year 2000. Based on these measurements and more precise climate modeling, scientists can now predict with strong confidence that the Bay Area will see an additional 10 inches of sea level rise by 2050. Beyond 2050, scientists expect sea levels to rise much faster than the current rate, partly because of positive feedback loops associated with global ice melt. Even the most conservative estimates suggest sea levels will rise a minimum of 40 inches by 2100 and as much as 16 feet if the global ice continues to melt faster than previously estimated.

So, what does sea level rise mean for the Bay Area and the people who live here?

San Francisco Bay is one of the most urbanized estuaries in the world. The majority of our seven million Bay Area residents live and work within a half mile from the Bay. We’ve filled in over 80% of the wetlands that once ringed the Bay and built our communities right at the edge of a bay that is expanding faster every day. We can look to King Tide events to show us the areas of this urbanized coastline that will be at risk in the near future.

As I mentioned, King Tides already bring higher sea levels into our coastal communities and flood urban infrastructure, reaching highways and roads in several areas throughout our region, including San Francisco, Marin, Alameda, and San Mateo counties. What I find of particular interest in the images above are the clear skies, demonstrating that the streets are flooded from ocean tides, not rainfall. However, add rainfall and tidal action and these “interesting” images can become downright devastating. The water you see on the pavement and in the streets during the King Tides indicate where the sea level was at that moment in those areas and we can expect to see that sea level every day in 2050 or even earlier. Combining those extreme high tides with large storms could result in devastating impacts, as you can see in the last two images.

Transition zones and rising tides

The Bay has expanded and contracted several times throughout history, but early humans hadn’t established permanent structures at the edges so the wetlands and the people that relied on them were able to migrate inland. Ten thousand years ago, sea levels were rising so quickly that every generation of early humans living along the coast or Bay was probably forced to retreat inland. Wetlands historically transitioned from low tidal marsh to upland terrestrial habitat across areas that spanned a mile or more. Today, most of our existing wetlands are squeezed up against urban infrastructure with narrow or no transition zones so these wetlands have nowhere to migrate. Healthy wetlands act as a sponge, slowing down and soaking up large volumes of water, so healthy wetlands help to keep coastal communities safe by buffering the effects of severe storms and flooding. With narrow transition zones and no migration space, our urban coastal tidal wetlands will drown as the sea continues to rise and will no longer provide the services we need unless we plan ahead.

In 1999, over 100 scientists, managers, and urban planners published the Baylands Goals Report, which became the basis for wetland restoration in the Bay Area and identified the need to conserve and restore 100,000 acres of healthy wetland habitat to provide healthy wetland ecosystems in the Bay Area. In October 2015, more than 200 scientists, natural resource managers, and urban planners published an update to the Baylands Goals report to include recommendations based on climate change. The Baylands Goals Science update includes an entire chapter dedicated to identifying types of transition zones and defining their services while emphasizing the need to accelerate restoration of these important areas of transition. For more information on the science update to the Baylands Goals Report, check out our Habitat Restoration Director’s blog, Baylands and Climate Change and to learn more about the general benefits of transition zones, check out my blog, What is Life without Transition?.

The solutions to climate change challenges are complex, but rising to the top of the list of challenges is the issue of big funding needs. Save The Bay is excited to be working on an important measure to invest critical funding in restoration projects. We are working with the Bay Restoration Authority to place a $12 parcel tax on the ballot throughout the nine-county Bay Area which will produce about half a billion dollars for Bay restoration over the next 20 years.

Communities can help to prepare for sea level rise by becoming involved with and supporting tidal wetland conservation and restoration. So it goes – wide, healthy wetlands between the Bay and urban infrastructure help to keep coastal communities safe from sea level rise.

If you fancy taking pictures and want to help document areas at risk for flooding as sea level rise, use this map to plan your shoot times and locations to photograph the high water in your community this King Tide season and submit your photos to the California King Tides Project.

State of the San Francisco Bay-Delta Estuary Conference 2015

 

To a greater extent than at any such gathering before, panel after panel at this year’s State of the Estuary Conference focused on the impacts that climate change will have on our Bay. Photo: Jill Clardy
Panel after panel at this year’s State of the Estuary Conference focused on the impacts that climate change will have on our Bay. Photo: Jill Clardy

Our planet’s climate is changing, the number of species on this planet is decreasing, sea level is rising as Earth’s ice continues to melt, and coastal communities throughout the world are already incurring devastating impacts from these changes. What does this mean for us in the Bay Area? That’s the exact question addressed in the 2015 State of the San Francisco Estuary Conference recently held in Oakland, CA.

Historical and modern extent of tidal Marsh in the Bay-Delta Estuary. Source: State of the Estuary, 2015
Historical and modern extent of tidal Marsh in the Bay-Delta Estuary. Source: State of the Estuary, 2015

The Bay-Delta Estuary has lost 90 percent of its’ historical wetlands due to diking, mining, bayfill, development, and freshwater diversions. We’ve made improvements to policies and practices in the Bay Area in the past fifty-five years to regain some of those lost tidal marshes, but now climate change poses a new threat to our beloved Bay.

Climate change hazards to the Bay Delta Estuary and coastal communities drove the conference themes this year including: shoreline erosion, accommodation space for shoreline migration, sea level rise adaptation, resilient landscapes, ideas to combine green and grey protective infrastructures, and managed retreat of humans from the coast. This conference also addressed issues related to the drought in California, such as the need to restore freshwater flows to the Bay Area watershed, water quality concerns, and competition for water rights among agriculture, fisheries, industrial needs, and human consumption as the drought continues.

Climate change is a looming threat and solutions are needed for both the short and long term. This conference emphasized the need to experiment while we implement and find solutions that also serve multiple purposes to both address short term impacts and to help plan for long term impacts. We need effective plans, policies that support those plans, and funding to make it all happen.

These conversations have been building on each other for decades and have intensified in the past several years as researchers, policymakers, environmental managers, and urban planners have learned how to collaborate more effectively (although there is still a ways to go). Before climate scientists had the kind of information they now have, they had predictions with big holes in them. The wise knew that we couldn’t let those holes slow us down in our planning for the future, rather we needed to find smart ways to move forward with the best available information. We needed plans that could adapt as we learned new things.

The data is in, Climate Change is no longer a problem of the future

Multipurpose options for more resilient levees, habitats, and shoreline protection. Source: Oro Loma Demonstration Project, 2015
Multipurpose options for more resilient levees, habitats, and shoreline protection. Source: Oro Loma Demonstration Project, 2015

Three important reports that reveal our latest understanding of climate predictions were presented at this conference, the Pulse of the Bay Report, the State of the Estuary 2015 report, and the update to the 1999 Baylands Ecosystem Habitat Goals Report. The Pulse of the Bay Report covers the state of water quality in the San Francisco Bay as it stands today and provides predictions and possibilities for what the water quality might be in 50 years from now in 2065. The State of the Estuary 2015 report highlighted the current health of the Bay and Delta based on 28 indicators and indicates the need to manage the Bay-Delta estuary as a whole, rather than two complete separate entities. The Bay and the Delta are both part of the estuary and feedback into each other, yet they historically have been managed in very different ways and for very different purposes. This report discusses these stark differences in management of the lower estuary (San Francisco Bay) and the upper estuary (Suisun Bay and Delta). In short, the health of the lower estuary has greatly improved over the years due to tighter regulations on sewage and chemical waste inputs and continued restoration. In contrast, the health of the upper estuary is in steady decline and there are relatively few efforts to restore these areas.

Several presentations at the State of the Estuary Conference covered the recommendations provided in this Baylands Ecosystem Habitat Goals Update, which will be released later this month (Oct. 2015). The original report provided recommendations for restoration and conservation of tidal wetlands, managed ponds, and wildlife species in the Bay. A major goal identified in this report was to restore and conserve 100,000 acres of healthy wetland habitat. The 1999 report provided the structure and common goals needed to secure funding for large restoration projects and prompted the largest restoration project on the west coast, the South Bay Salt Pond Restoration Project. At the time, climate predictions were too uncertain for the Goals reporting group to provide specific recommendations based on them but the holes in climate predictions are now much smaller than before and with new information, the collaborative effort that produce the 1999 Habitat Goals report regrouped to provide an update with recommended goals for the Bay Area considering climate change. Also included in this update is an entire chapter co-authored by Save The Bay’s very own Habitat Restoration Director, Donna Ball. This chapter is dedicated to highlighting the benefits and services provided by the estuarine-terrestrial transition zone, which are an important focus when developing sea level rise adaptation strategies for the Bay Area.

3 Keys to Addressing Climate Change: Innovation, intellect, and funding:

Also discussed in great length was the Oro Loma Sanitary District Horizontal Levee project, which is an innovative, experimental project in collaboration with an industrial stakeholder, researchers, practitioners, managers, and engineers and it’s also the kind of collaborative, multi-purpose thinking we need in order to make progress in time to help the Bay Area adapt to sea level rise. The term horizontal levee is used to describe a more natural version of an earthen levee. A horizontal levee has a broad, low-gradient slope with native vegetation that can provide a holding place for storm water runoff that might otherwise flood coastal communities, slow down and hold tidal surges and provide a buffer between storms and people. In short, this project provides an opportunity for the sanitary district to address the issue of aging wastewater infrastructure and the threats that rising sea level will have on the wastewater system altogether. Other potential benefits of this project include providing native habitat at the treatment site where it would otherwise not exist and providing an opportunity for groundwater recharge. If successful, this experimental project could inform the 41 other coastal wastewater treatment plants in the Bay Area.

Continuing to focus on what more can be done, Letitia Grenier, SFEI’s Resilient Landscape’s Program Director, pointed out that less than 20 percent of undeveloped space in the Bay Area is protected from five feet of sea level rise. We currently have about 50,000 acres of healthy conserved and restored wetlands, but we need to restore 50,000 acres more to reach the goal identified in the Goals report. Several restoration plans are in place for these undeveloped areas, but in most cases, the limiting factor is funding. The Bay Area receives approximately $5 million annually from the federal government, but we need an estimated $1.43 billion to complete the restoration of the areas waiting to be restored. To address this problem, the Bay Restoration Authority is preparing to propose a small parcel tax to voters in all nine Bay Area counties to raise the funding needed to meet Bay Area restoration goals. Jim Levine of the Bay Area Council Water Committee, John Bourgeois of the California Coastal Conservancy’s South Bay Salt Pond Restoration Project, and several others announced the plans for  this June 2016 ballot measure. If the ballot measure passes in 2016, that funding can then be leveraged for much needed federal funding.

In 1969 California Governor Ronald Reagan made the San Francisco Bay Conservation and Development Commission a permanent state agency to regulate development in and around the Bay.
In 1969 California Governor Ronald Reagan made the San Francisco Bay Conservation and Development Commission a permanent state agency to regulate development in and around the Bay.

In addition to the lack of funding, outdated policies have complicated some large-scale restoration work. In the years leading up to 1969, Save The Bay played an instrumental role in creating the first coastal zone management agency ever, The Bay Conservation and Development Commission (BCDC). This agency continues to protect and manage the Bay with vigor, but some policies don’t consider current restoration needs, which were unforeseen when they were written. BCDC brought a large presence to this conference as they discussed their strategies for the Bay Area in this climate, including their efforts to update their policies to facilitate the restoration needed as determined by the top scientists, managers, planners, and stakeholders in the Bay Area.

With Restoration Scientists, Climate Scientists, Engineers, Environmental Managers, Economists, and Policymakers all under the same roof providing their various perspectives in concert to the theme of the San Francisco Bay-Delta Estuary’s future in light of climate change, the fuzzy map forward is becoming more defined.

What Is Life Without Transition? Why Estuarine-Terrestrial Transition Zones Matter

transition zone restoration
Save The Bay staff and volunteers are restoring this slope adjacent to a newly restored wetland at the Eden Landing Ecological Reserve.

The majority of Bay Area residents live and work within a half mile from the Bay, which makes the San Francisco Estuary one of the most urbanized estuaries in the world. Humans have valued the Bay for various ecosystem services throughout history and have modified the Bay to take advantage of some of those services. For example, humans have diked large areas of the Bay for commercial salt production and duck hunting, and have built trails close to the Bay so that they can enjoy the cultural services that the Bay provides. They have also hampered some of those services by filling and paving over large areas of the Bay to build urban infrastructure, and until the 1960’s, used the Bay as a place to dispose of garbage and sewage. It has only been the last several decades that the general public began to realize the importance of the natural ecosystem services the SF Bay provides.

San Francisco Bay was once ringed by healthy wetland habitats. Those wetlands, in many cases, gradually transitioned from tidal wetlands to upland terrestrial habitat. Those areas of gradual transition would often extend for a mile or more, comprising large expanses of native grasses and salt tolerant plants utilized by abundant wildlife populations. Over time, those transition areas have been squeezed between urban infrastructure and the Bay. These areas at the marsh-upland interface, that we call estuarine-terrestrial transition zones, are important because they provide important and unique ecosystem functions and services. Faced with climate change, transition zones can provide important ecosystem services, including buffering hazards associated with sea level rise such as flooding and erosion, and providing a place for wetlands to migrate inland. In addition, the transition zone provides nutrient cycling, filtration of pollutants from urban runoff, and support for biological diversity.

Save The Bay focuses its restoration effort on creating functional transition zone habitat in areas that lack transition zones. Using a carefully selected site-specific plant palette, we restore transition zone vegetation in areas such as the Eden Landing Ecological Reserve (ELER) in Hayward adjacent to recently restored salt ponds where transition zone habitat is lacking. Several of these former salt ponds are being breached to restore natural tidal flow as part of the South Bay Salt Pond Restoration (SBSPR) Project. Save The Bay has been working with the SBSPR Project at the ELER to vegetate the slopes adjacent to these ponds in order to provide functions such as high tide refuge and cover to avoid predation for marsh animals during high tides. Sign up for a volunteer program and join Save The Bay’s Habitat Restoration Team to learn more about functional transition zone habitat and important ecosystem services at our sites throughout San Francisco Bay.

Watch this PBS NewsHour clip about the importance of restoring transition zones for wildlife.

Leopards, Angels, and Hounds, Oh My! — Sharks in the San Francisco Bay

broadnose sevengill shark
The broadnose sevengill shark is one of six shark species that live in San Francisco Bay.

The Bay Area is lucky to have six resident shark species and one species of ray living in the San Francisco Bay, although there were once more. Several species of sharks are considered threatened or vulnerable because they tend to mature relatively late in life and put a lot of effort into reproducing only a few pups at a time. Most sharks in the Bay rely on wetland areas, which have been reduced by 90% in the past 100 years. The San Francisco estuary was once adequately surrounded by tidal wetlands that provide calm, warm, nutrient-rich feeding, breeding, and nursery grounds for many species of flora and fauna, including sharks. Now, although the wetland areas have become sparse, our Bay sharks rely on these areas for pupping and feeding on smaller fishes (including other sharks) and invertebrate animals that live on the Bay floor, such as clams, shrimp, and crabs. Sharks are important to the web of life because they help to keep other marine and estuarine populations healthy and strong by feeding on weak members, and thereby increasing resources for the strong, which are more successful at perpetuating their population.

The most abundant shark in the San Francisco Bay is the leopard shark (Triakis semifasciata), whose population in the Bay has already greatly benefited from the levee breaches of the former salt ponds in the South Bay. These breaches in the South Bay have re-introduced tidal flow, restoring feeding grounds for leopard sharks, which eat burrowing clams and crustaceans in shallow waters.

We also have angels in the Bay! The Pacific angel shark (Squatina californica) can be difficult to spot in the Bay since they spend a good portion of their time camouflaged on the Bay floor. They are ambush predators, meaning they lie and wait (sometimes for days) on the bottom, slightly buried in the sand. When their preferred meal of flounder, halibut, or crab swims or crawls by, they pop out and snatch it. They have a body form that closely resembles rays and skates but one way to identify an angel shark is to look at its pectoral fins, which are completely attached to the bodies of rays and skates but are distinct appendages in the angel shark.

Our Bay is a popular winter “staycation” destination for the spiny dogfish (Squalus acanthias), which is among the most abundant species of shark in the world due to its global distribution. Although this species is globally abundant, the World Conservation Union has declared that this species is vulnerable to a population collapse due to overfishing. A major reason the National Marine Fisheries Service declared the spiny dogfish fishery is not sustainable is because this shark has a gestation period of up to 2 years, which is the longest known among all sharks! This shark is named for its poisonous spines located in front of each dorsal fin (they’ve got two), which they use for defense against larger prey, such as the broadnose sevengill shark, which also lives in the Bay. Spiny dogfish eat smaller fishes and crustaceans, which are easily found in the Bay, but the spiny dogfish must go offshore to satisfy its appetite for squid.

We’ve got two species of smoothhound sharks in the Bay, which are among the few sharks that give live birth, as opposed to using egg cases. The two species of smoothhounds in the Bay are most easily distinguished by color, brown and grey. Brown smoothhounds (Mustelus henlei) tag-team the spiny dogfish for entrance into the Bay during spring and summer to pup and benefit from this glorious nursery ground before returning to open waters for the rest of the year. The grey smoothhound (Mustelus californicus) is often found hanging out with schools of leopard sharks, which have a similar diet of shrimp, crab, clams, and small fish.

The top predator in the Bay is the broadnose sevengill shark (Notorynchus cepedianus), except when good ol’ Whitey (white shark, Carcharodon carcharias) enters the bay briefly for a sevengill snack. To be clear, white shark tagging studies have shown that white sharks will enter the San Francisco Bay only occasionally and for brief stints, so they’re not considered to be residents of the Bay. The broadnose sevengill preys on small marine mammals and fishes, including sharks and sometimes even smaller sevengills. The sevengill is named for having seven pairs of gill slits, as opposed to the five that most sharks have and is considered to be among the least evolved of all sharks. The broadnose sevengill is a voracious predator but does not dine on humans. Sevengill sharks were once prevalent along the entire California coast and a common catch in the commercial fisheries until the fishery collapsed due to population decline. Sevengill populations now seem to be reduced to two areas, San Francisco and Humboldt Bays, which indicates that conservation of these areas are important to the future of this species.

We also have the bat ray (Myliobatis californica) in the Bay! Bat rays are common in bays and estuaries from the Gulf of California up to Oregon and they are a preferred snack for the leopard shark. Did you know that sharks, rays, and skates all belong to the same class of species called the Chondrichthyes? They all share common features that separate them from other fishes, the most notable being that chondrichthyans all have cartilaginous vertebrae and modified scales, called dermal denticles, which are structurally similar to teeth. These dermal denticles are what give sharks, rays, and skates their dual directional skin texture.

Humans have had a complicated relationship with sharks. Although humans have been the top predator of many shark species, it is the sharks that humans have demonized for quite some time. The word “shark” often evokes images of a larger-than-life “great” white shark with powers to snatch humans off of 36-foot boats. More recently, shark researchers and naturalists have worked hard to counter that evil image by downplaying the sharks’ potential to harm humans. While I believe this downplay has been an important counter for the shark reputation, I think it’s important to maintain a solid respect for sharks in general by respecting their role in the ecosystem as well as their ability to harm humans if provoked. Sharks are absolutely necessary for ecosystem health and the majority of sharks will leave you alone if you do the same. No sharks living in the Bay have ever been documented to kill humans, but most of them can harm you if you bother them. Sharks are highly instinctual – they’ll usually stay away from you if they can. They don’t want to kiss you, and if you get your fingers near their mouths, they can do at least as much damage as a dog.

Humans have almost decimated several species of shark, but sharks have done no such damage to the human population. A great example of human-caused near decimation of a shark species is the soupfin shark (Galeorhinus zyopterus) in the San Francisco Bay. The Bay was once an important nursery ground for soupfin sharks but since the soupfin shark Pacific coast fishery collapsed in the 1940’s due to ruthless and inhumane overfishing for its fins, they are now a rare sight within the Bay. In this light, one might consider humans to be the monsters. This human tendency to exploit nature for its own purpose is the same tendency that enabled the decimation of wetland habitats, leaving us with a mere 10% of what we used to have.

Save The Bay, our partners, and supporters have made great strides in advocating for saving and creating more wetlands.  However, when it comes to reaching our collective goal of establishing 100,000 acres of healthy wetland habitat in the Bay, “we’re gonna need a bigger boat”. We need as many people as we can get on this “boat” to help conserve and restore habitat that will help natural populations thrive. Breaching levees and allowing natural tidal flow to the ex-Cargill salt ponds has re-introduced some of those important shark feeding and breeding grounds that have been lost. Save The Bay works to restore function to the SF Bay wetland ecosystem, including those former salt ponds, by providing native vegetation in the transition zones between those wetlands and the upland habitats. Among other things, this vegetation ensures a healthy detrital input to the wetland, which then fuels the food web that these sharks need.  The sharks are doing their part to help keep populations healthy, and we’re continuing to provide more and more habitat to enable that action. I’d like to thank all of our volunteers and partners who have worked to achieve 45,000 acres of healthy wetland habitat, now we just need 55,000 more!

Help us to support wetland restoration by providing the essential vegetation for a healthy and functional estuarine ecosystem. Sign up to volunteer.

Biodiversity: More Is Not Always Better

Happy Biodiversity Day! Most of us have heard the word biodiversity being tossed around as an important subject that requires our attention, but why is biodiversity so important? This topic is much more difficult to address than you might think. Biodiversity refers to the level of variation of life within an ecosystem. Plants and animals have everything they need to live sustainably together in an ecosystem that has healthy biodiversity. Although biodiversity is a crucial subject in restoration science, there can be a misunderstanding that more biodiversity is always better. Researchers are finding that the types of species in an ecosystem are just as important as the number of species and more isn’t always better. Save The Bay confronts this issue of biodiversity every time we design a habitat restoration plan for tidal wetland transition zones within the San Francisco Bay.

biodiversity
Biodiverse restored transition zone habitat at Eden Landing with invasive monoculture of mustard on the other side of the fence.

To better understand this idea that more biodiversity isn’t always better when designing habitat restoration plans, let’s first consider what habitat restoration means and what’s being restored. Effective environmental restoration will restore ecosystem function. Ecosystem function involves biological, geochemical, and physical processes that vary between systems, but maintain a specific balance within each ecosystem, and that balance is delicate. Plants, animals, water, and earth all contribute to how ecosystems function, and when one of those contributions change, so do the others. Those changes not only displace the effectiveness and sustainability of food webs (Zedler and Kercher, 2004) but they also affect ecosystem services that humans rely on, such as food, water, medicine, transportation, employment, inspiration, shelter, and protection… to name a few. For example, an important ecosystem service that wetlands offer humans is their role as breeding and nursery grounds for economically important fish species, including the Pacific anchovy, California halibut, rainbow trout, and Chinook salmon. Tidal wetlands also provide important feeding and stopping grounds for migrating birds, which not only contribute to maintaining healthy populations of those economically important fish species, but also help to maintain healthy native insect and rodent populations.

Once researchers learned the importance of biodiversity and discovered it was diminishing, so began the mission to determine the cause for this great loss. Many factors have contributed to our worldwide decrease in biodiversity, and tidal wetlands are among the greatest victims. 90% of the San Francisco Bay wetlands have been destroyed due to bayfill, contamination, industrial use, and fragmentation. This hardship makes life difficult (if not impossible) for the San Francisco native species that depend on a healthy wetland habitat, and therefore, the wetlands have developed a decreased immunity to invasions by non-native species. Invasive non-native species thrive when conditions are difficult for the natives and they often completely take over entire ecosystems if left unchecked. Not all non-native species are invasive, just the ones that demolish the native diversity. And San Francisco Bay has the greatest number of invasive species anywhere in the western hemisphere.

As environmental scientists learned more about the intricacies of biodiversity, it became apparent that diversity should reflect the needs of the resident flora and fauna, since both are so interconnected. This observation may indicate that, while biodiversity offers the benefit of ecosystem stability, restoring an ecosystem to a sustainable functioning state should be the ultimate goal. So, rather than focusing on the blanket idea of increasing biodiversity across the board, researchers and practitioners have begun to implement the idea of restoring the biodiversity that has been lost in a particular area. That means that if a particular ecosystem historically was home to only a few species, practitioners are better off trying to restore the functions that those few species provided to that area, which is the entire point of restoration. Save The Bay works hard to understand and recognize the specific ecosystem functions at each of our sites and the specific native plant species that are capable of supporting those functions. Join us on one of our community-based restoration programs to ensure that the flowers have bees for pollination, the birds have a place to perch and nest, and the salt marsh harvest mouse has sufficient refugia during high tide.

Reference:
Zedler, JB and Kercher S. (2004). Causes and consequences of invasive plants in wetlands: Opportunities,
opportunists, and outcomes. Critical Reviews in Plant Sciences. 23(5):431-452.