Integrating Studies of Anatomy, Physiology, and Behavior into Conservation Strategies for the Imperiled Cyprinid Fishes of the Southwestern United States

Over the last 100 years, fishes native to the Southwestern United States have faced a myriad of biotic and abiotic pressures which has resulted in most being federally listed as endangered or threatened. Most notably, water diversions and the introduction of non-native fishes have been the primary culprits in causing the downfall of native fish populations. We describe how recent studies of morphology, physiology, and behavior yield insights into the failed (occasionally successful) management of this vanishing biota. We describe how understanding locomotor morphologies, physiologies, and behaviors unique to Southwestern native fishes can be used to create habitats that favor native fishes. Additionally, through realizing differences in morphologies and behaviors between native and non-native fishes, we describe how understanding predator–prey interactions might render greater survivorship of native fishes when stocked into the wild from repatriation programs. Understanding fundamental form–function relationships is imperative for managers to make educated decisions on how to best recover species of concern in the Southwestern United States and worldwide.

Clarifying Effects of Environmental Protections on Freshwater Flows to—and Water Exports from—the San Francisco Bay Estuary

Understanding and resolving conflicts over management of scarce natural resources requires access to information that helps characterize the problem. Where information is lacking, perceived differently by stakeholders, or provided without relevant context, these conflicts can become intractable. We studied water management practices and constraints that affect the flow of water into and through the San Francisco Bay estuary — home to six endangered fish species and two water export facilities owned by the state and federal governments that serve millions of people and large expanses of agricultural land in California. Media reports reflect widely held beliefs that environmental regulations, and particularly protections for endangered fish species, frequently limit water diversions and substantially increase freshwater flow to San Francisco Bay. We analyzed long-term trends in freshwater flow to San Francisco Bay relative to annual runoff from its Central Valley watershed, and the frequency and magnitude of specific regulatory and physical constraints that govern operations of the water export facilities. We found that the percentage of Central Valley runoff that reached San Francisco Bay during the ecologically sensitive winter-spring period declined over the past several decades, such that the estuary experienced drought conditions in most years. During a 9-year period that included a severe natural drought, exports were constrained to maintain salinity control as often as to protect endangered fish populations. Salinity-control and system-capacity constraints were responsible for Delta outflow volumes that dwarfed those related to protection of fish and wildlife populations, endangered or otherwise. These results run counter to common media narratives. We recommend rapid synthesis and easily accessible presentation of data on Central Valley water diversions and constraints on them; such data should be contextualized via comparison to regional hydrology and water management system capacity.

Mitigating Toxic Planktonic Cyanobacterial Blooms in Aquatic Ecosystems Facing Increasing Anthropogenic and Climatic Pressures

Toxic planktonic cyanobacterial blooms are a pressing environmental and human health problem. Blooms are expanding globally and threatening sustainability of our aquatic resources. Anthropogenic nutrient enrichment and hydrological modifications, including water diversions and reservoir construction, are major drivers of bloom expansion. Climatic change, i.e., warming, more extreme rainfall events, and droughts, act synergistically with human drivers to exacerbate the problem. Bloom mitigation steps, which are the focus of this review, must consider these dynamic interactive factors in order to be successful in the short- and long-term. Furthermore, these steps must be applicable along the freshwater to marine continuum connecting streams, lakes, rivers, estuarine, and coastal waters. There is an array of physical, chemical, and biological approaches, including flushing, mixing, dredging, application of algaecides, precipitating phosphorus, and selective grazing, that may arrest and reduce bloom intensities in the short-term. However, to ensure long term, sustainable success, targeting reductions of both nitrogen and phosphorus inputs should accompany these approaches along the continuum. Lastly, these strategies should accommodate climatic variability and change, which will likely modulate and alter nutrient-bloom thresholds.

Automatic feedback control algorithm for canal for a quick upstream water supply interruption in the case of an emergency

For the sudden upstream water interruption in the canal of an emergency, the existing research method guiding gate control is mainly feed-forward compensation algorithm, under which algorithm the interruption of water diversions is the upstream first and then the downstream. In order to achieve a more flexible water demand for different water diversions purpose, this study used PI water level difference feedback control algorithm to control the gate under this condition. The research results showed that the PI water level difference feedback control algorithm can make the change trend of water level of multi-pool close and reduce the rate of water level decline, and thus prolong the continuous delivery time of pools with offtake delivery demand under sudden upstream water interruption. Moreover, the PI water level difference method has good robustness and can be applied to more complex combinations of inflow and delivery changes. This study provides another way of thinking for the regulation of the gate in the case of sudden upstream water interruption.