The collaborative design which joins wildlife biologists and hydrologists enables ARMI to ask the kinds of questions it does about the environmental variables that affect amphibians in a truly integrated manner. Understanding how water quality, quantity, or timing affects amphibians is a critical component of ARMI research.

A hydrologist is associated with each ARMI region and works with the ARMI PI to develop and implement research and monitoring projects. These collaborations enable ARMI to ask questions about how water quality (e.g., nutrients, agro-chemicals, acidification), water budgets (e.g., ground and surface water models), storm surge impacts, or other hydrologic conditions can affect amphibian life cycles, disease transport, or habitat quality.


Hydrologic Investigations
USGS Toxics Substances Hydrology program

Pesticide lab.
K. Jones (USGS) extracting a water sample for pesticide analysis at Pesticide Fate Research Laboratory. Photo by: R. Todd.

Water - ARMI Papers & Reports

Papers & Reports Effects of harmful algal blooms on amphibians and reptiles are underreported and underrepresented
Authors: Brian J Tornabene; Kelly L Smalling; Blake R Hossack
Date: 2024-07-05 | Outlet: Environmental Toxicology & Chemistry
Harmful algal blooms (HABs) are a persistent and increasing problem globally, yet we still have a limited knowledge about how they affect many wildlife. Although semi-aquatic and aquatic amphibians and reptiles have experienced large declines and occupy environments where HABs are increasingly problematic, their vulnerability to HABs remains unclear. To inform monitoring, management, and future studies, we conducted a literature review and synthesized studies and reported mortality events describing effects of cyanotoxins from HABs on freshwater herpetofauna. Our review identified 37 unique studies and 71 endpoints (no-observed-effect and lowest-observed-effect concentrations) involving 11 amphibian and three reptile species worldwide. Responses varied widely among studies, species, and concentrations used in experiments. Concentrations causing lethal and sublethal effects in experiments were generally 1–100 µg/L, which is near the mean value of reported events but 70times less than the maximum cyanotoxin concentrations reported in the environment. However, one species of amphibian was tolerant to concentrations of 10,000 µg/L, demonstrating potentially immense differences in sensitivities. Most studies focused on microcystin-LR (MC-LR), which can increase systemic inflammation and harm the digestive system, reproductive organs, liver and kidneys, and development. The few studies on other cyanotoxins illustrated that effects resembled those of MC-LR at similar concentrations, but more research is needed to describe effects. All experimental studies were on larval and adult amphibians; there were no such studies on reptiles. Experimental work with reptiles and adult amphibians is needed to clarify thresholds of tolerance. Only nine mortality events were reported, mostly for reptiles. Given that amphibians likely decay faster than reptiles, which have tissues that resists decomposition, mass amphibian mortality events from HABs have likely been underreported. We propose seven major areas to focus future efforts to enhance our understanding of effects and monitoring of HABs on herpetofauna that fill important roles in freshwater and terrestrial environments.
Data Release Mercury concentrations in amphibian tissues across the United States, 2016-2021
Authors: Colleen S Emery; Collin A Eagles-Smith; Kelly L Smalling; Blake R Hossack; Brian J Tornabene; Michael J Adams; Adam R Backlin; Adrianne B Brand; Robert N Fisher; Jill Fleming; Brad M Glorioso; Daniel A Grear; Evan HC Grant; Brian J Halstead; Patrick M Kleeman; David AW Miller; Erin Muths; Christopher A Pearl; Jennifer C Rowe; Caitlin T Rumrill; Hardin J Waddle; Megan E Winzeler
Date: 2023-08-23
Comma-separated values (.csv) file containing data related to amphibian sampling across the United States between 2016 and 2021. Data files contain mercury concentrations in amphibian and dragonfly tissues, mercury concentrations in sediment, as well as amphibian morphometrics, and habitat and climate characteristics where the samples were collected.
Papers & Reports Native amphibian toxin reduces invasive crayfish feeding with potential benefits to stream biodiversity
Authors: Gary Bucciarelli; Sierra J. Smith; Justin J. Choe; Phoebe D. Shin; Robert N Fisher; Lee B Kats
Date: 2023-09-13 | Outlet: BMC Ecology and Evolution 23, 51
Biodiversity is generally reduced when non-native species invade an ecosystem. Invasive crayfish, Procambarus clarkii, populate California freshwater streams, and in the Santa Monica Mountains (Los Angeles, USA), their introduction has led to trophic cascades due to omnivorous feeding behavior and a rapid rate of population growth. The native California newt, Taricha torosa, possesses a neurotoxin, tetrodotoxin (TTX), that affects freshwater animal behavior. Given P. clarkii has a limited evolutionary history with TTX, we hypothesized that TTX may affect crayfish feeding behaviors. To determine if TTX affects P. clarkii behavior, we measured cumulative movement and various feeding behaviors of P. clarkii exposed to (i) waterborne, ecologically realistic concentrations of TTX (~?3.0?×?10??8 moles/L), (ii) an anuran chemical cue to account for intraguild cues, or (iii) a T. torosa chemical cue with quantitated TTX in it (~?6.2?×?10??8 moles/L).

We found that the presence of TTX in any form significantly reduced crayfish movement and decreased the amount of food consumed over time. Crayfish responses to the anuran treatment did not significantly differ from controls.

Our laboratory results show that naturally occurring neurotoxin from native California newts limits invasive crayfish foraging and feeding rates, which may play a role in preserving local stream ecosystems by limiting invasive crayfish behaviors that are detrimental to biodiversity.
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