Invasive Aquatic Vegetation Management in the Sacramento–San Joaquin River Delta: Status and Recommendations

Section: Aquatic Weed Removalmentioning

confidence: 99%

Section: Aquatic Weed Removalmentioning

confidence: 99%

How to Respond? An Introduction to Current Bay–Delta Natural Resources Management Options

Sommer¹

2020

“…Slow-moving warm-water conditions expanded, favoring non-native aquatic species, including plants. Aquatic weed management could not stop the steady expansion of Egeria densa and other submersed aquatic macrophytes throughout the Delta (Ta et al 2017;Hard 2018). The expansion of submersed aquatic vegetation likely aided Largemouth Bass and sunfish populations, which use it for habitat (Brown 2003;Nobriga and Feyrer 2007;Ferrari et al 2014).…”

Section: Priority Actions and Environmental Responsementioning

confidence: 99%

“…Many uncertainties remain, especially given the high temperatures and low snowpack that distinguished this drought from previous recorded droughts. The extreme conditions created new uncertainties around the long-term effects of brackish irrigation water on Delta soil conditions (Aegerter and Leinfelder-Miles 2016); maintaining the Shasta cold-water pool to support winterrun Chinook Salmon (Mount et al 2017b); the effect of hatchery supplementation on winterrun Chinook Salmon (NMFS 2016); the effects of increased straying of fall-run Chinook Salmon from trucking (Dedrick and Baskett 2018); the control of long-term expansion of some aquatic weeds (Ta et al 2017); and the response of Microcystis to drought and water quality (Lehman et al 2018).…”

Section: Scientific Studies Of the Droughtmentioning

confidence: 99%

Drought and the Sacramento–San Joaquin Delta, 2012–2016: Environmental Review and Lessons

Durand

Bombardelli

Fleenor

et al. 2020

This paper reviews environmental management and the use of science in the Sacramento–San Joaquin Delta during California’s 2012–2016 drought. The review is based on available reports and data, and guided by discussions with 27 agency staff, stake-holders, and researchers. Key management actions for the drought are discussed relative to four major drought water management priorities stated by water managers: support public health and safety, control saltwater intrusion, preserve cold water in Shasta Reservoir, and maintain minimum protections for endangered species. Despite some success in streamlining communication through interagency task forces, conflicting management mandates sometimes led to confusion about priorities and actions during the drought (i.e., water delivery, the environment, etc.). This report highlights several lessons and offers suggestions to improve management for future droughts. Recommendations include use of pre-drought warnings, timely drought declarations, improved transparency and useful documentation, better scientific preparation, development of a Delta drought management plan (including preparing for salinity barriers), and improved water accounting. Finally, better environmental outcomes occur when resources are applied to improving habitat and bolstering populations of native species during inter-drought periods, well before stressful conditions occur.

“…'Omic approaches, applied across multiple phytoplankton species, can therefore help algal bloom occurrences, species distribution, and habitat requirements -as well as the impact of contaminants -to be better understood; for example, herbicides that are directly applied to surface waters to control invasive aquatic vegetation such as Brazilian waterweed (Egeria densa), water hyacinth (Eichhornia crassipes), and water primrose (Ludwigia spp.) (Ta et al 2017) on primary production. Conducting mechanistic studies across trophic levels is of particular importance in a system that has been described as food limited (Kimmerer et al 2018), because this will provide information needed to address the cause, rather than treating the symptom.…”

Section: Phytoplakton Speciesmentioning

confidence: 99%

Review of and Recommendations for Monitoring Contaminants and their Effects in the San Francisco Bay−Delta

Connon

Hasenbein

Brander

et al. 2019

Legacy and current-use contaminants enter into and accumulate throughout the San Francisco Bay−Delta (Bay−Delta), and are present at concentrations with known effects on species important to this diverse watershed. There remains major uncertainty and a lack of focused research able to address and provide understanding of effects across multiple biological scales, despite previous and ongoing emphasis on the need for it. These needs are challenging specifically because of the established regulatory programs that often monitor on a chemical-by-chemical basis, or in which decisions are grounded in lethality-based endpoints. To best address issues of contaminants in the Bay−Delta, monitoring efforts should consider effects of environmentally relevant mixtures and sub-lethal impacts that can affect ecosystem health. These efforts need to consider the complex environment in the Bay−Delta including variable abiotic (e.g., temperature, salinity) and biotic (e.g., pathogens) factors. This calls for controlled and focused research, and the development of a multi-disciplinary contaminant monitoring and assessment program that provides information across biological scales. Information gained in this manner will contribute toward evaluating parameters that could alleviate ecologically detrimental outcomes. This review is a result of a Special Symposium convened at the University of California−Davis (UCD) on January 31, 2017 to address critical information needed on how contaminants affect the Bay−Delta. The UCD Symposium focused on new tools and approaches for assessing multiple stressor effects to freshwater and estuarine systems. Our approach is similar to the recently proposed framework laid out by the U.S. Environmental Protection Agency (USEPA) that uses weight of evidence to scale toxicological responses to chemical contaminants in a laboratory, and to guide the conservation of priority species and habitats. As such, we also aimed to recommend multiple endpoints that could be used to promote a multi-disciplinary understanding of contaminant risks in Bay−Delta while supporting management needs.