Temporal Dynamics of an Estuary: San Francisco Bay


Book Description

Estuaries are highly dynamic systems subject to changes occurring over a spectrum of time scales ranging from very short periods (e. g. over a tidal cycle) to geologic time scales. The nature of an estuary reflects complex responses to many driving forces, each having a characteristic frequency (or frequencies) of change. For example, freshwater inflow to estuaries varies daily in response to short-term events such as storms, seasonally, and between years as a result of longer-term climatic variability. Other important components of weather, e. g. wind speed/ direction and daily insolation, also vary over time scales ranging from hours to years. Tidal amplitude changes continuously with dominant frequencies associated with the semi-diurnal cycle, the fortnightly neap-spring, and the semi-annual cycle. Temporal dynamics of these driving forces evoke responses in the form of changing (I) circulation patterns and mixing, (2) sediment composition and transport, (3) solute speciation and distribution, (4) composition and abundance of particulates, (5) biomass, species composition, and productivity of plant and animal communities, (6) rates of material exchange between the sediments, water column, and atmosphere, and (7) bioavailability of trace metals and other pollutants. The purpose of this book is to examine the temporal dynamics of these properties and processes in the San Francisco Bay estuary.




An Urban Estuary in a Changing World


Book Description

Estuarine and coastal ecosystems face both large scale physical environmental stresses from climate change and local scale community changes, including non-native species introductions. In northern California, USA, climate change projections indicate increasingly severe droughts in the future punctuated by more frequent, intense winter storms, significantly affecting freshwater outflow to estuaries like San Francisco Bay. Using long-term physical and biological data sets coupled with experiments, I found drastic changes in epifaunal communities in the Bay between years with extreme high and low freshwater outflow (Chapter 1). In dry years (low outflow), competition determines community composition, but in wet years (high outflow), low salinity stress shifts the community to being recruitment limited, with community membership determined by the availability of larvae to recruit. Shifts in outflow extremes drive changes in the dominant species, resulting in altered community performance (Chapter 2). I experimentally tested the effect of functional group diversity on community performance in different outflow regimes. Communities containing more functional groups generally occupied more space, but the strength of this effect varied from year to year. In the absence of normally dominant species during a wet year, resident community functional group diversity had no effect on subsequent invasion by non-resident species. These results suggest that outcomes of short-term, unreplicated studies of biodiversity-ecosystem function relationships may thus be contingent on prevailing conditions. Finally, I assessed the risk posed by the aquarium fish trade for introducing non-native fish species to the San Francisco Bay-Delta using an inventory of fish species for sale, a model comparing fish physiological tolerances to environmental parameters, and a telephone survey of store representatives' knowledge and attitudes toward invasions (Chapter 3). This analysis showed that the local aquarium trade includes at least five and as many as twenty-seven species that could potentially survive in the Bay-Delta. Management efforts for this vector should focus on improving labeling and identification of fish species in stores, expanding available information on fish physiological tolerances, educating customers and store employees about the risks of pet release, and providing better options for responsible disposal of unwanted fish.







Where the river meets the ocean - Stories from San Francisco Estuary


Book Description

What is an estuary? Where do they occur? How do they work? Who lives there? And why are estuaries important to our planet? This collection will answer all of these questions and more. Estuaries are places where fresh water from rivers moving downstream from the mountains mixes with salty water moving upstream from the ocean. Estuaries thus contain both fresh and salty water habitats (places) where many kinds of plants and animals can live and grow. San Francisco Estuary is the largest estuary on the West Coast of the United States and is home to millions of people, plants and animals. Our scientists have been studying all aspects of the San Francisco Estuary for nearly 50 years and we have 35 stories to tell about the people, plants, and animals in the estuary. We will tell you horror stories of how tiny poisonous plants and vampire fish kill other fish, and we have success stories of how conservation saves the lives of tiny mice in marshes and birds along the Pacific Flyway. The Collection of stories is divided into six sections, so you can easily find the stories that interest you the most. The first section describes the many kinds of habitats in the estuary, including rivers, shallow bays, wetlands, and marshes, and what makes them a good home for plants, animals, and people. In the second section, the water quality scientists will describe how they use boats, special instruments, and new technology to determine whether the water is healthy for people, plants, and animals. In the third and fourth sections we will tell stories about how plants and animals live in the estuary. Microbiologists will describe the tiny, microscopic plants and animals that live in the estuary, what makes them grow, how important they are as food for animals and why they are sometimes poisonous. Fish scientists will describe the many kinds of fish in the estuary and how we measure their growth, determine where they are, what they eat, and the ways they use both fresh and saltwater habitats to grow and raise their young. In the fifth section, scientists will discuss how invasions of plants and animals from outside of the estuary have changed habitats and the survival of native plants and animals. Lastly, in the sixth section, we will share how scientists in the estuary are using new technologies and management actions to control invasions of unwanted plants and animals, increase the growth of native plants and animals, improve water quality and restore habitats in the estuary.




Hydrological Changes and Estuarine Dynamics


Book Description

Water development projects have altered the environmental flow landscapes where dams and diversions have been built, and this could have effects on coastal resources, particularly in estuaries. Water is an important human resource and water needs grow as populations grow. However, freshwater inflow to the coast is fundamental to the functioning of estuaries. Can we have stable, secure, and sufficient water resources for people and still protect estuarine health? Estuaries are the most productive environments on Earth, and this is in part due to freshwater inflow, which dilutes marine water, and transports nutrients and sediments to the coast. Estuaries are characterized by salinity and nutrient gradients, which are important in regulating many biological processes. As water is diverted for human consumption, it is common for many environmental problems to appear. While many countries have water quality programs, few are dealing with water quantity alterations. The first step is to define marine resources to protect, and the water quality conditions those resources need to thrive. The second step is to determine the flow regimes needed to maintain the desired water quality conditions. Finally, many regions are using adaptive management programs to manage freshwater resources. These programs set goals to protect ecosystem resources, identify indicators, and monitor the indicators over time to ensure that the goals are appropriate and resources are protected. Case studies demonstrate that monitoring and research can determine the ecological and socio-economical impacts of altered freshwater inflows, and stakeholders and managers can make well-informed decisions to manage freshwater inflows to local coasts wisely. ​




Ecology, Conservation, and Restoration of Tidal Marshes


Book Description

The San Francisco Bay, the biggest estuary on the west coast of North America, was once surrounded by an almost unbroken chain of tidal wetlands, a fecund sieve of ecosystems connecting the land and the Bay. Today, most of these wetlands have disappeared under the demands of coastal development, and those that remain cling precariously to a drastically altered coastline. This volume is a collaborative effort of nearly 40 scholars in which the wealth of scientific knowledge available on tidal wetlands of the San Francisco Estuary is summarized and integrated. This book addresses issues of taxonomy, geomorphology, toxicology, the impact of climate change, ecosystem services, public policy, and conservation, and it is an essential resource for ecologists, environmental scientists, coastal policymakers, and researchers interested in estuaries and conserving and restoring coastal wetlands around the world.




Ecosystems of California


Book Description

This long-anticipated reference and sourcebook for CaliforniaÕs remarkable ecological abundance provides an integrated assessment of each major ecosystem typeÑits distribution, structure, function, and management. A comprehensive synthesis of our knowledge about this biologically diverse state, Ecosystems of California covers the state from oceans to mountaintops using multiple lenses: past and present, flora and fauna, aquatic and terrestrial, natural and managed. Each chapter evaluates natural processes for a specific ecosystem, describes drivers of change, and discusses how that ecosystem may be altered in the future. This book also explores the drivers of CaliforniaÕs ecological patterns and the history of the stateÕs various ecosystems, outlining how the challenges of climate change and invasive species and opportunities for regulation and stewardship could potentially affect the stateÕs ecosystems. The text explicitly incorporates both human impacts and conservation and restoration efforts and shows how ecosystems support human well-being. Edited by two esteemed ecosystem ecologists and with overviews by leading experts on each ecosystem, this definitive work will be indispensable for natural resource management and conservation professionals as well as for undergraduate or graduate students of CaliforniaÕs environment and curious naturalists.




Endangered Environments


Book Description