The Use of Smolt Survival Estimates to Quantify the Effects of Habitat Changes on Salmonid Stocks in the Sacramento-San Joaquin Rivers, California

Canada Department of Fisheries and Oceans (DFO) | July 1st, 1989

The value of ecosystem services in global marine kelp forests

Nature Portfolio (Springer Nature) | April 18th, 2023

While marine kelp forests have provided valuable ecosystem services for millennia, the global ecological and economic value of those services is largely unresolved. Kelp

While marine kelp forests have provided valuable ecosystem services for millennia, the global ecological and economic value of those services is largely unresolved. Kelp forests are diminishing in many regions worldwide, and efforts to manage these ecosystems are hindered without accurate estimates of the value of the services that kelp forests provide to human societies. Here, we present a global estimate of the ecological and economic potential of three key ecosystem services - fisheries production, nutrient cycling, and carbon removal provided by six major forest forming kelp genera (Ecklonia, Laminaria, Lessonia, Macrocystis, Nereocystis, and Saccharina). Each of these genera creates a potential value of between $64,400 and $147,100/hectare each year. Collectively, they generate between $465 and $562 billion/year worldwide, with an average of $500 billion. These values are primarily driven by fisheries production (mean $29,900, 904 Kg/Ha/year) and nitrogen removal ($73,800, 657 Kg N/Ha/year), though kelp forests are also estimated to sequester 4.91 megatons of carbon from the atmosphere/year highlighting their potential as blue carbon systems for climate change mitigation. These findings highlight the ecological and economic value of kelp forests to society and will facilitate better informed marine management and conservation decisions.

Thermal performance in juvenile hatchery Oncorhynchus tshawytscha: aerobic scope tests over a range of environmental temperatures

U.S. Environmental Protection Agency (EPA) | March 15th, 2016

In heavily-altered ecosystems, anthropogenic factors coupled with global climate change have drastically changed available habitats for many native fishes (Cloe

In heavily-altered ecosystems, anthropogenic factors coupled with global climate change have drastically changed available habitats for many native fishes (Cloern and Jassby 2012, Moyle et al. 2013). Water projects such as large hydropower dams have altered flow and temperature regimes (Poff et al. 1997, Bunn and Arthington 2002, Marchetti and Moyle 2001), and reduced or degraded native spawning and rearing habitats (Sheer and Steel 2006, Pelicice and Agostinho 2008), while global climate change has resulted in warmer overall river temperatures (Cloern and Jassby, 2012). As ecologically relevant environmental variables like temperature have shifted, fish populations have subsequently declined (Cloern and Jassby, 2012; Hanak et al., 2015). Native California fishes have been disproportionately affected by these changes, and precipitous population declines have been observed for several species, some of which are listed under the Endangered Species Act (ESA) (Moyle et al. 2013). Despite documented correlations between fish declines and changes in environmental variables such as temperatur e (Moyle and Leidy, 1992; Moyle et al. 2010; Quiñones and Moyle 2014), there has been a profound lack of data available on the actual physiological and/or behavioral mechanisms driving fish population declines. Physiological performance data, such as information on aerobic scope, may help provide mechanistic explanations for both how and why fish population declines are occurring. Furthermore, as populations decline and management becomes more crucial for population persistence, thermal limits, optimal thermal ranges, and data on how key physiological processes, such as metabolic rate, change in response to environmental variables becomes more important. Therefore, the objectives of our study were to quantify the aerobic scope of juvenile Chinook salmon ( Oncorhynchus tshawytscha) acclimated to two different rearing temperatures (14 or 20 °C) and tested over a temperature range of 12-26°C.

Tijuana River Valley Historical Ecology Investigation

San Francisco Estuary Institute (SFEI) | January 2nd, 2017

The Tijuana River Valley Historical Ecology Investigation addresses a regional data gap by reconstructing the landscape and ecosystem characteristics of the river valley

The Tijuana River Valley Historical Ecology Investigation addresses a regional data gap by reconstructing the landscape and ecosystem characteristics of the river valley prior to the major modifications of the late 19th and 20th centuries. The research presented here, funded by the California State Coastal Conservancy, supplies foundational information at the regional and system scale about how the Tijuana Estuary, River, and valley looked and functioned in the recent past, as well as how they have changed over time. The ultimate goal of this study is to provide a new tool and framework that, in combination with contemporary research and future projections, can support and guide ongoing restoration design, planning, and management efforts in the valley.

Toward a better understanding of freshwater fish responses to an increasingly drought-stricken world

Reviews in Fish Biology and Fisheries (Springer) | January 8th, 2019

Drought is a constant and important consequence of natural climatic processes and most freshwater fishes have adaptations to counter its effects. However, a changing glob

Drought is a constant and important consequence of natural climatic processes and most freshwater fishes have adaptations to counter its effects. However, a changing global climate coupled with increasing human demand for water is reducing the availability of fresh water to fishes and contributing to more frequent and intense drought around the globe. A clear understanding of how fishes, fish habitat, and fisheries are affected by extended drought is needed to help resolve conflicts over water. We therefore identify key questions and research themes to promote the conservation of freshwater fishes as drought increases in length, frequency and severity. (1) How does drought affect fish habitat? (2) What is drought tolerance in fishes? (3) What are drought refuges for fishes? (4) What kills fish during drought? (5) What is the nature of species succession in drought-stricken waters? (6) What are the long-term consequences of drought to fishes? (7) How does climate change affect drought-fish interactions? (8) How does drought influence fisheries? Our limited ability to provide answers to these questions indicates that fish diversity and abundance worldwide is threatened by drought. Planning, including collection of long-term data, is necessary so that conservation and water re-allocation strategies can be implemented in a timely manner to maintain habitats necessary to support biodiversity during drought periods. Without increased understanding of physiological and behavioural factors that determine the tolerance of fishes to drought, it will not be possible to establish realistic targets for management and restoration of populations and species confronting increasing drought frequency and severity.

Toward a Preemptive Ecology for Rapid, Global, and Increasingly Irreversible Environmental Change: A Discussion Paper with Implications for Research and Management in the Sacramento-San Joaquin Delta

Delta Stewardship Council (Delta Council) | November 15th, 2019

People have extensively modified the Sacramento-San Joaquin Delta since the 1850s. Rapid change is not new, but the nature of rapid change that is beginning to be experie

People have extensively modified the Sacramento-San Joaquin Delta since the 1850s. Rapid change is not new, but the nature of rapid change that is beginning to be experienced has new qualities. The Delta Independent Science Board, working in conjunction with the Delta Science Program and the Delta Plan Interagency Implementation Committee, is assessing the adequacy of environmental and ecological research in the Delta, how well that research is addressing emerging challenges, and how it might be improved. This paper is a part of that process. Each member of the Delta Independent Science Board has contributed to this document, but there is not a consensus among the members around the full content of this paper. This paper is written to inform and stimulate discussion around controversial yet important issues. 

Toward Natural Infrastructure to Manage Shoreline Change in California

California Natural Resources Agency (CNRA) | August 27th, 2018

Flooding and erosion caused by rising sea levels and powerful storms threaten property throughout coastal California. To protect against these climate-change related thr

Flooding and erosion caused by rising sea levels and powerful storms threaten property throughout coastal California. To protect against these climate-change related threats, landowners will certainly take action, and the default industry standard response has been to try to “hold the line” against the encroaching sea by constructing seawalls, dikes, levees and other forms of coastal armoring. While armoring may in some cases provide acceptable short-term protection, armoring also tends to accelerate shoreline erosion, exacerbating hazards to people and leading to the eventual loss of critical wildlife habitat and public beaches. Natural Shoreline Infrastructure can be as effective as armoring, while having the added benefits of preserving coastal habitat and public access. Recognizing this, California agencies have mandated that decision-makers prioritize its use in planning and investment decisions. Yet, planners have encountered many stumbling blocks as they have tried to incorporate these approaches into coastal resilience plans. Major obstacles include: a lack of a common definition and shared terminology; lack of expertise; lack of precedent; and the absence of siting guidance and technical design standards. Here, we set out to enable planners to adopt Natural Shoreline Infrastructure by filling in the missing information. With the input of dozens of coastal managers who served on our Technical Advisory Committee, we developed a definition and collected a list of case studies where Natural Shoreline Infrastructure has already been successfully deployed in California. Drawing from these and other projects, we collected into one place the first detailed technical guidance for implementation, including siting criteria and design thresholds. These criteria inform decisions about where and when to use six types of Natural Shoreline Infrastructure (e.g. sand dunes, seagrass beds). Using Monterey Bay and Ventura County projects as examples, we demonstrate how to use the technical guidance in tandem with spatial data to match a particular shoreline environment with appropriate Natural Shoreline Infrastructure options, creating “blueprints” for action. The information in this report is intended to facilitate the use of Natural Shoreline Infrastructure along California’s coast, improving the resilience of communities and habitats in the face of climate change.

Tree height explains mortality risk during an intense drought

Nature Portfolio (Springer Nature) | September 26th, 2019

Forest mortality is accelerating due to climate change and the largest trees may be at the greatest risk, threatening critical ecological, economic, and social be

Forest mortality is accelerating due to climate change and the largest trees may be at the greatest risk, threatening critical ecological, economic, and social benefits. Here, we combine high-resolution airborne LiDAR and optical data to track tree-level mortality rates for ~2 million trees in California over 8 years, showing that tree height is the strongest predictor of mortality during extreme drought. Large trees die at twice the rate of small trees and environmental gradients of temperature, water, and competition control the intensity of the height-mortality relationship. These findings suggest that future persistent drought may cause widespread mortality of the largest trees on Earth.

Trends in Fish and Invertebrate Populations of Suisun Marsh January 2017 - December 2017

University of California, Davis (UC Davis) | January 31st, 2019

Suisun Marsh, at the geographic center of the northern San Francisco Estuary, is important habitat for native and non-native fishes. The University of California, Davis,

Suisun Marsh, at the geographic center of the northern San Francisco Estuary, is important habitat for native and non-native fishes. The University of California, Davis, Suisun Marsh Fish Study, in partnership with the California Department of Water Resources (DWR), has systematically monitored the marsh's fish populations since January 1980. The study’s main purpose has been to determine environmental and anthropogenic factors affecting fish distribution and abundance. 

Trends in nitrogen, phosphorus, and sediment concentrations and loads in streams draining to Lake Tahoe, California, Nevada, USA

Science of the Total Environment (Elsevier) | August 19th, 2020

Lake Tahoe, a large freshwater lake of the eastern Sierra Nevada in California and Nevada, has 63 tributaries that are sources of nutrients and sediment to the lake. The

Lake Tahoe, a large freshwater lake of the eastern Sierra Nevada in California and Nevada, has 63 tributaries that are sources of nutrients and sediment to the lake. The Tahoe watershed is relatively small, and the surface area of the lake occupies about 38% of the watershed area (1313 km2). Only about 6% of the watershed is urbanized or residential land, and as part of a plan to maintain water clarity, wastewater is exported out of the basin. The lake's clarity has been diminishing due to algae and fine sediment, prompting development of management plans. Much of the annual discharge and nutrient load to the lake results from snowmelt in the spring and summer months. To understand the relative importance of land use, climate, forest management, and other factors affecting trends in nutrient stream concentrations and loads, a Weighted Regression on Time Discharge and Season (WRTDS) model simulated these trends over a time frame of >25 years (mid-1970s to 2017). All studied locations generally show nitrate concentration and load trending down. Ammonium concentration and load initially trended down then increased continuously after 2005. Some locations show initially decreasing orthophosphate trends, followed by small significant increases in concentration and loads starting around 2000 to 2005. Total Kjeldahl nitrogen, total phosphorus and suspended sediment mostly trended downward. Overall, the trends in various forms of nitrogen were observed at most sites irrespective of the degree of development and indicate a change in ecological conditions is affecting the nitrogen cycle throughout the watershed, most likely attributable to forest aggradation and fire suppression. Ratios of bioavailable nitrogen in the form of nitrate and ammonium to orthophosphate have also trended downward during the period of record suggesting a shift of these streams from phosphorus limited to nitrogen limited.