All posters submitted for the 2021 virtual CABW Meeting are found below.
The “live” virtual poster session will be held in a Zoom Rooms video conference. Zoom Rooms is a platform that will allow you have a discussion with the poster author in a single video conference room, just like how you would interact in-person. Posters can be presented in different rooms giving the audience and the presenters a chance to interact, ask questions, follow discussion, both in verbal, audio formats and through the chat feature.
The time on the agenda for the poster session is for live Q&A with the poster presenters and co-authors. During this time, the posters will be judged by the Cal-SFS student poster judging committee. During this live session, audience and presenters can convers and get live feedback (verbal or through chat) from the audience and immediate responses from presenters.
If you are interested, make sure that you enter the Zoom Rooms video conference meeting during this time of the session. Once you enter the video conference meeting, the main room will have a list of all of the poster titles with their corresponding breakout rooms that each poster is in. You can select which room you want to enter by clicking on the “Breakout Rooms” button at the bottom of the zoom screen (if the Breakout Room button is not visible, check under “More”). Then click on “Join” next to the room you want to enter and select “yes” when prompted. When you are done visiting a poster and talking to the author, you can select “Leave Room” button at the bottom right which will take you back to the main room. You can then enter other rooms. If you have problems or questions, there will be a facilitator in the main room that will help. Once you are done, you can leave the Zoom Rooms video conference meeting by clicking on “Leave”.
The goal of hosting a poster session is to encourage student attendance and participation in CABW & Cal-SFS, as students are the future members, researchers, and managers of freshwater in California. It is highly encouraged to attend this unique virtual poster session experience to interact and engage with the poster authors!
Tidal streams connected to estuaries can sequester carbon ten times as quickly as forest. However, aquatic microbial decomposers emit carbon into the atmosphere by breaking down dead, riparian leaves. Our study quantifies the rate of litter breakdown by microbes in tidally influenced stream water across a range of salinities from 5,000-20,000 μS/cm. At three sites, we deployed leaf packs of a known mass and electrical conductivity (EC) data loggers. Although we did not investigate microbial species richness or abundance, it is likely the fine mesh leaf packs allowed microbes to decompose litter and prevented aquatic invertebrates from decomposing litter. Increasing salinity was associated with increasing breakdown rates, explaining 24% of the variation after accounting for the effects of temperature. This relationship may be the result of increasing abundance and/or efficiency of microbes in higher EC water. There may also be a shift in microbial communities as salinities increase. Coastal freshwater streams will likely experience salinity intrusion from climate-driven sea-level rise and storm surges. We conjecture that increasing salinity in estuaries may lead to greater carbon cycling by microbial communities in coastal streams.
Healthy freshwater rivers are populated by aquatic invertebrates from the orders ephemeroptera, plecoptera, and trichoptera often referred to as ETP. However, tidal streams have metacommunities that include freshwater ETP from upstream and marine invertebrates from downstream. We quantified the composition of invertebrates in tidal streams to see how assemblages change across a salinity gradient, from 2596.77 uS/cm to 20270.5 uS/cm. We deployed leaf packs in three tidal streams (Pajaro, Aptos, Baldwin) to sample aquatic and marine invertebrates. Comparing low salinity rivers to high salinity rivers, we observed that the high salinity rivers have less ETP and New Zealand mudsnails. We also observed that high salinity rivers have an increased number of non-EDT invertebrates. Biologically, this means as salinity increases, we see a decrease in ETP composition. It is expected that many coastal freshwater rivers will experience salinity intrusion resulting from sea-level rise. It is likely that aquatic invertebrate metacommunities will indicate diminishing biological health with increasing tidal influence.
Salmon are essential to the health of many river ecosystems in the United States, requiring careful monitoring of their populations. Environmental DNA (eDNA) offers a promising new method for enumerating salmon, but remains limited by poor understanding of salmon eDNA fate (transport, degradation, settling, resuspension). We aim to characterize salmonid eDNA fate at the reach-scale using a random forest modeling approach. We will add Brook Trout (S. fontinalis) eDNA to 10 river sites of the central California coast, analyze eDNA samples collected at sequential distances downstream using qPCR, and determine the eDNA loss over distance at each site. We will then model eDNA loss over distance as a function of river characteristics, including discharge, width, depth, temperature, pH, conductivity, biological oxygen demand (BOD), substrate cobble size, and biofilm thickness. Here, we present initial results describing salmonid eDNA fate at the reach-scale. Once completed, this study will provide insight into the relative impacts of various environmental characteristics on eDNA fate in a natural system, and offer an approach for characterizing reach-specific eDNA fate profiles. These findings will lay the groundwork for eDNA-based enumeration of salmon, while improving knowledge of eDNA detection probabilities across river taxa.
The intersex condition of freshwater fishes across the Unites States has been widely documented. We examined the effect of wastewater on the intersex condition of largemouth bass (Micropterus salmoides) in the effluent-dominated urban headwaters of the Santa Ana River. The Santa Ana River is a highly urbanized waterway sustained by treated wastewater. This study quantifies the intersex condition of one invasive fish predator along a spatial gradient below the two major wastewater outflows that rewet the Santa Ana River. Using a linear model we analyzed the relationship between distance from wastewater outflow sites and the proportion of intersex largemouth bass. Eleven percent of all male largemouth bass surveyed were characterized as intersex and distance from wastewater outflow was significantly correlated with the proportion of intersex largemouth bass in a reach. Our study documents an early investigation into the relationship between effluent outflows and intersex condition in one invasive fish species. This work demonstrates the need for future research to investigate the impact of wastewater outflow on native and invasive fishes in this waterway.
The urban Santa Ana River is an effluent-dominated waterway within dense urban development. In 2018 groundwater wells steadied the flow regime of the Santa Ana River, preventing the river from running dry when wastewater treatment plants shut down. This alteration coincided with a decrease in the native Santa Ana sucker (Catostomus santaanae) and Arroyo chub (Gila orcuttii) populations, and an increase in the invasive Largemouth bass (Micropterus salmoides) population. In November 2019, two wastewater facilities that rewet the urban headwaters shut down, and an invasive removal and native fish rescue was carried out. We received the stomachs of removed invasive Largemouth bass and analyzed their diets. We found that native fish made up a smaller percentage of diets than we had hypothesized and that benthic macroinvertebrates were an important food source for Largemouth bass in this section of the river.
Climate change is predicted to advance Sierra Nevada snowmelt up to two months. This would result in stream communities experiencing earlier peak discharge followed by longer low flow conditions. Longer low flow periods will increase temperature, reduce habitat availability, and reduce water velocity. These impacts may harm macroinvertebrate communities, but have rarely been studied at the food web level.
This project compared the effects of possible future flow regimes on stream food webs. We tested three flow regime treatments: current low flow conditions; low flow extended by three weeks (mitigated climate change scenario); and low flow extended by six weeks (unmitigated climate change scenario) using the Sierra Nevada Aquatic Research Lab’s artificial streams. We performed stable isotope analysis on macroinvertebrate samples and basal resources collected before and after treatment.
Preliminary data suggests the structure of the food web remained mostly consistent throughout the experiment. Some taxa showed slight changes, however. Oligochaetes occupied a larger isotopic niche space following extended low flow treatment. Snails seasonally occupied a larger isotopic niche space in all treatments following low flows.
Overall, these results suggest macroinvertebrate communities may remain resilient to climate change-induced extended low flows, as some taxa consume more diverse food sources.
Wastewater effluent has dominated streamflow in many Southern California rivers since the mid-to-late 1900s, but wastewater treatment plant (WTP) operators plan to increase water recycling to fulfill conservation mandates. In the Los Angeles and Santa Clara Rivers, effluent inputs could be reduced as early as 2022. Consequently, additional river reaches are likely to run dry seasonally, affecting in-stream and riparian ecological communities. Previous California research has focused on aquatic invertebrates in wadeable and perennial streams, focusing less on dry streams or terrestrial invertebrates. In July 2021, I monitored aquatic and terrestrial invertebrates at twelve Santa Clara River and LA River sites, which represented a gradient of hydrologic and riparian conditions upstream and downstream of effluent discharges. I hypothesize that in habitats of comparable hydroperiod, aquatic invertebrate communities upstream of WTP effluent inputs will be more diverse, more sensitive, and less abundant than at downstream sites, which may be exposed to increased flows, temperature, and nutrients. Terrestrial invertebrates upstream of effluent inputs will be more diverse, less sensitive, and less abundant because they need to resist harsher conditions. In upcoming field seasons, I will replicate this study design, quantifying how effluent discharge changes affect the composition and structure of invertebrate communities.
Water chemistry affects organisms at all levels of the food web. Water quality alteration from natural conditions can seriously impact the overall well-being of the surrounding habitat, survival of native species, and human health. To better understand baseline water chemistry levels, we are creating random forest models for various ionic and integrated water quality parameters. These models are designed using both static (i.e., Geology, Soils, etc.) and dynamic (i.e., mean evapotranspiration, precipitation, and temperature) EPA StreamCat predictor variables. The baseline California water chemistry estimates produced by these models are aimed to assist in California water quality and habitat management regarding various situations. These situations include urban development projects, overall habitat health, and endangered species monitoring. Early static models for Chloride and TDS had R2 value ranges between 0.39 - 0.52. Other variable selection methods, VSURF and RFE, are being considered to determine if they will help improve overall model performance. In addition to the variable selection methods, adding the dynamic predictors to the modeling dataset will allow for a better understanding of the natural fluctuations in analyte levels throughout the high and low flow seasons, providing a more diverse management application of the model.
In Southern California, USA, the invasive red swamp crayfish Procambarus clarkii poses a significant threat to native aquatic fauna. Studies have suggested that artificial refuge traps (ARTs) resembling crayfish burrows can be used to remove invasive crayfish, but, to date, no studies have focused on optimizing ART design and deployment to maximize crayfish catch. Our month-long study tested the effect of modifications on ART diameter, color, and soak time on P. clarkii catch effectiveness across 160 traps. We evaluated catch data by creating multiple candidate generalized linear mixed models predicting P. clarkii catches with different modeling parameterizations and a priori hypothesized predictor variables. In our study, ARTs removed a total of 240 red swamp crayfish with no incidental bycatch. Larger P. clarkii (2–6-cm) were found more frequently in 5.1-cm-diameter traps, and smaller P. clarkii (1–4 cm) were found more frequently in 2.5-cm-diameter traps. Catch numbers varied between trap types, with black-colored 5.1-cm-diameter traps removing the greatest amount of the total P. clarkii caught in the study (mean = 0.27, SD = 0.29; 35% of the total caught) and black-colored 2.5-cm-diameter traps removing the least amount (mean = 0.09, SD = 0.55; 12% of the total). Further, ART deployment duration was an important predictor variable for candidate models, where ARTs with 4-d and 7-d deployment durations had lower catch/unit effort than traps with 1-d and 2-d deployments. This factorial experiment is the 1st study to suggest specific design modifications to ARTs that optimize invasive red swamp crayfish removal without incurring non-target incidental bycatch. This study demonstrates that ARTs can be a valuable tool for conservation managers interested in restoring streams through invasive crayfish removal, especially where there are sensitive biological resources.
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