Deconstructing dams and disease: predictions for salmon disease risk following Klamath River dam removals

The health of fish populations and the river systems they inhabit have broad ecological, cultural, recreational, and economic relevance. This is exemplified by the iconic anadromous salmonid fishes native to the West Coast of North America. Salmon populations have been constrained since the mid nineteenth century by dam construction and water reallocation. In the Klamath River (Oregon and California, USA), a series of dams built in the early-mid 20th century cut the basin in two and blocked anadromous fish access to more than 600 river kilometers. This dramatic loss of habitat, coupled with infectious diseases and resulting epizootics, have impacted the wellbeing of these salmonid populations. In 2023-2024, the Klamath River will undergo the largest river restoration project in US history. Removal of the four lowermost dams will cause profound physical changes to the river, including flow, water temperature, and channel geomorphology. The dam removals will reconnect the lower and upper portions of the basin, and provide fish passage after a century of segregation. Reestablishment of upstream and downstream fish movements will also alter the occupancy and abundance of the salmonid hosts and their pathogens. The increased habitat availability and longer migration routes will increase duration of pathogen exposure and potential impacts on juvenile survival and adult pre-spawn mortality. However, restoration of more natural flow and sediment regimes will decrease overall fish disease risk by disrupting complex parasite life cycles. To better understand these multifarious, competing factors, we review the salmonid species in the Klamath River, and provide an overview of their historical pathogen challenges and associated diseases and use this as a framework to predict the effects of dam removals on disease dynamics. Our review and predictions are a synthesis of expertise from tribal biologists, fish health specialists and fish biologists, many of whom have lived and worked on the Klamath River for decades. We conclude with recommendations for expansion of current pathogen monitoring and research efforts to measure changes in host-pathogen dynamics basin-wide

B-Cyclin/CDKs Regulate Mitotic Spindle Assembly by Phosphorylating Kinesins-5 in Budding Yeast

Although it has been known for many years that B-cyclin/CDK complexes regulate the assembly of the mitotic spindle and entry into mitosis, the full complement of relevant CDK targets has not been identified. It has previously been shown in a variety of model systems that B-type cyclin/CDK complexes, kinesin-5 motors, and the SCFCdc4 ubiquitin ligase are required for the separation of spindle poles and assembly of a bipolar spindle. It has been suggested that, in budding yeast, B-type cyclin/CDK (Clb/Cdc28) complexes promote spindle pole separation by inhibiting the degradation of the kinesins-5 Kip1 and Cin8 by the anaphase-promoting complex (APCCdh1). We have determined, however, that the Kip1 and Cin8 proteins are present at wild-type levels in the absence of Clb/Cdc28 kinase activity. Here, we show that Kip1 and Cin8 are in vitro targets of Clb2/Cdc28 and that the mutation of conserved CDK phosphorylation sites on Kip1 inhibits spindle pole separation without affecting the protein's in vivo localization or abundance. Mass spectrometry analysis confirms that two CDK sites in the tail domain of Kip1 are phosphorylated in vivo. In addition, we have determined that Sic1, a Clb/Cdc28-specific inhibitor, is the SCFCdc4 target that inhibits spindle pole separation in cells lacking functional Cdc4. Based on these findings, we propose that Clb/Cdc28 drives spindle pole separation by direct phosphorylation of kinesin-5 motors

Home range, spatial dynamics, and growth of Moapa dace (Moapa coriacea)

Moapa dace (Moapa coriacea) is an endangered thermophilic minnow (Family: Cyprinidae) native to the upper Muddy River which originates at geothermal springs in southeastern Nevada, USA. Historically Moapa dace occupied tributaries and the main stem of the Muddy River totaling 18 kilometers of stream habitat near the geothermal sources where water temperatures are between 26.0°C and 32.0°C. Due to habitat fragmentation, water diversion, and invasive species introductions during the early and mid-1900's Moapa dace populations drastically declined. In 1997, following the invasion of the non-native blue tilapia (Oreochromis aureus), a fish barrier was installed isolating three tributaries from the main stem of the Muddy River for the protection of native aquatic organisms above the barrier. During this study Moapa dace were restricted to stream habitat above this barrier totaling 2.8 kilometers. The goals of this study were to determine the home range size, spatial dynamics, and growth of Moapa dace in these three tributaries of the Muddy River. A mark-recapture method using baited minnow traps was implemented and genetic tagging of individuals based on their unique genotypes using ten polymorphic microsatellites was used to identify individuals over a three year period (October 2009 - September 2012). Using geographic information systems (GIS) I was able to demonstrate that home range density (number of individual home ranges per square meter) was most restricted in a fragmented tributary and home range density increased in a tributary immediately following stream habitat restoration. Mean home range length of individuals increased in the last year of this study (141.3 meters), was greatest in the largest tributary (215.2 meters), and was the least in the fragmented tributary (70.5 meters). Growth rates of Moapa dace drastically decline in individuals over 40 mm (fork length), are highest between May and July, and lowest between September and November. Using Fulton's body condition factor (K=W/L3) two distinct periods of low (January - March) and high (May - November) body condition were discovered. Growth rates and body condition were both significantly higher in individuals with home ranges over 25 meters. The results of this study suggest that Moapa dace will immediately occupy stream habitat that has been recently restored to increase stream velocities and re-emphasizes the importance of habitat connectivity as it relates to an individual's ability to maximize energy intake

Case Study: Generalizing Ecological Site Concepts of the Colorado Plateau for Landscape-Level Applications

On the Ground • Numerous ecological site descriptions in the southern Utah portion of the Colorado Plateau can be difficult to navigate, so we held a workshop aimed at adding value and functionality to the current ecological site system. • We created new groups of ecological sites and drafted state-and-transition models for these new groups. • We were able to distill the current large number of ecological sites in the study area (ca. 150) into eight ecological site groups that capture important variability in ecosystem dynamics. • Several inventory and monitoring programs and landscape scale planning actions will likely benefit from more generalized ecological site group concepts.The Rangelands archives are made available by the Society for Range Management and the University of Arizona Libraries. Contact [email protected] for further information.Migrated from OJS platform March 202