Laura A Twardochleb

CA State Water Resources Control Board

Climate warming and species traits interact to influence predator performance, including individual feeding and growth rates. However, the effects of an important trait-predator foraging strategy-are largely unknown. We investigated the interactions between predator foraging strategy and temperature on two ectotherm predators: an active predator, t...

Motivation Freshwater insects comprise 60% of freshwater animal diversity; they are widely used to assess water quality, and they provide prey for numerous freshwater and terrestrial taxa. Our knowledge of the distribution of freshwater insect diversity in the USA is incomplete because we lack comprehensive, standardized data on their distributions...

Climate warming is altering life cycles of ectotherms by advancing phenology and decreasing generation times. Theoretical models provide powerful tools to investigate these effects of climate warming on consumer–resource population dynamics. Yet, existing theory primarily considers organisms with simplified life histories in constant temperature en...

Ecological Impacts of Drought on Suisun Bay and the Sacramento-San Joaquin Delta with special attention to the extreme drought of 2020-2022. Prepared By the Interagency Ecological Program Drought Synthesis Team

Motivation Aquatic insects comprise 64% of freshwater animal diversity and are widely used as bioindicators to assess water quality impairment and freshwater ecosystem health, as well as to test ecological hypotheses. Despite their importance, a comprehensive, global database of aquatic insect occurrences for mapping freshwater biodiversity in macr...

• Use of invertebrate traits rather than species composition may facilitate large-scale comparisons of community structure and responses to disturbance in freshwater ecology because the same traits potentially occur everywhere. In recent years, comprehensive invertebrate trait databases have been established at different scales (e.g., regions, cont...

The San Francisco Estuary is home to an important endangered fish called delta smelt. Delta smelt eat small, nutritious animals called zooplankton to survive and grow. In turn, zooplankton grow by eating microscopic plant-like organisms called phytoplankton. In the past, the Estuary was full of plankton and delta smelt. Because people have removed...

Global declines in biodiversity have the potential to affect ecosystem function, and vice versa, in both terrestrial and aquatic ecological realms. While many studies have considered biodiversity-ecosystem function (BEF) relationships at local scales within single realms, there is a critical need for more studies examining BEF linkages among ecolog...

Research into the relationships among climate, land use, and freshwater insect diversity at different spatial scales in the contiguous United States.

Body size of consumer species is a fundamental trait that influences the trophic ecology of individuals and their contribution to the functioning of freshwater ecosystems. However, the relationship between body size and trophic ecology can be highly variable both within and between closely-related and similarly-sized species. In this study we compa...

Impacts of invasive species may manifest most strongly if these organisms are highly distinct functionally from the native species they often replace. Yet, should we expect functional differences between native and invasive species of generalist organisms like freshwater crayfish? Some existing evidence has pointed to native and invasive crayfish s...

Residential shoreline and watershed development by humans are leading agents of environmental change in lake ecosystems that reduce abundances and diversity of littoral invertebrates. Invertebrate functional and life history traits are robust indicators of environmental quality and ecosystem functioning, yet surprisingly few studies have utilized t...

Non-native species are widely regarded as threats to ecosystem structure and function; however, these species may also provide benefits to ecosystems that have lost former functions to environmental degradation. This study evaluated whether non-native species provide prey resources or induce trophic cul-de-sacs (by diverting basal energy away from...

Development of skills in science communication is a well-acknowledged gap in graduate training, but the constraints that accompany research (limited time, resources, and knowledge of opportunities) make it challenging to acquire these proficiencies. Furthermore, advisors and institutions may find it difficult to support graduate students adequately...

Nonnative crayfish have been widely introduced and are a major threat to freshwater biodiversity and ecosystem functioning. Despite documentation of the ecological effects of nonnative crayfish from .3 decades of case studies, no comprehensive synthesis has been done to test quantitatively for their general or species-specific effects on recipient...

Omnivores can impact ecosystems via opposing direct or indirect effects. For example, omnivores that feed on herbivores and plants could either increase plant biomass due to the removal of herbivores or decrease plant biomass due to direct consumption. Thus, empirical quantification of the relative importance of direct and indirect impacts of omniv...

Results of model comparison for the 2008 experiment. ΔAICc is used to compare contrasting models; lower ΔAICc indicate a better model. Models that were substantially better, as evidenced by a ΔAICc of at least 2.0 of the next best model, are bolded. All models were basic linear models on either untransformed or transformed data. P-values refer to t...

Results of model comparison for the 2009 comparative study. Unless otherwise noted, all models are basic linear models. (DOCX)

Biomass of key invertebrate groups as a function of crayfish density from the 2008 density manipulation. Note y-axis data is log +1 transformed. Each points represents the invertebrate abundance of a given study pool from surber samplers, as a function of manipulated crayfish density. The lines in represent the best fit linear model that were signi...

Predators sometimes provide biotic resistance against invasions by nonnative prey. Understanding and predicting the strength of biotic resistance remains a key challenge in invasion biology. A predator's functional response to nonnative prey may predict whether a predator can provide biotic resistance against nonnative prey at different prey densit...

The frequency and severity of wildfire in North America has increased substantially in recent years, with relatively poorly understood impacts on aquatic systems. While these large-scale disturbances potentially pose a serious challenge for management and conservation of vulnerable species, these disturbances also can elucidate key biotic and abiot...

Dominant species can have wide-ranging impacts on food-web dynamics and ecosystem processes. Here we examined the direct and indirect impacts of the non-native omnivore, Signal Crayfish, on stream dynamics. In central California where we worked, these crayfish were introduced approximately 100 years ago. We performed a large-scale density manipulat...