Department of Biological Sciences Environmental predictors of schistosome parasite production in Michigan lakes Thomas R. Raffel, Ph.D. Madelyn Messner Department of Biological Sciences Oakland University Rochester, MI

Raffel Lab Approach: Spatial & temporal surveys Experiments at large & small scales Pollution effects on parasite communities Temperature & parasitism Statistical & predictive models

Pollution & trematodes example: (2008 Study with Jason Rohr Univ. S Florida) Cattle tank experiment: Herbicide Eutrophication Fertilizer +Snails +Cercariae

Temperature & trematodes: (Ongoing collaboration with Piet Johnson’s lab Univ. Colorado) Trematode biology is temperature-dependent Snail growth & reproductive rates Trematode development rate Cercaria production rate** BUT most studies ignore: Nonlinearities Variability Day

Temperature & trematodes: (Ongoing collaboration with Piet Johnson’s lab Univ. Colorado) Thermal Stress Hypothesis Depletion of host energy reserves at stressful temperatures Lower cercaria production following excessively warm periods Temperature-shift experiment: Predictions: Observations:

Temperature & trematodes: (Ongoing collaboration with Piet Johnson’s lab Univ. Colorado) Predictive model: Based on metabolic theory & dynamic energy budget theory Parameterized by measuring temperature-dependence of host food assimilation & respiration 13°C Acclimation 22°C Acclimation 28°C Acclimation

Temperature & trematodes: (Ongoing collaboration with Piet Johnson’s lab Univ. Colorado) Predictive model: Based on metabolic theory & dynamic energy budget theory Parameterized by measuring temperature-dependence of host food assimilation & respiration

Swimmer’s Itch Research Needs Better monitoring & detection methods Filtration + microscopy; Slide samplers (short-term) Quantitative PCR (DNA detection; medium-term) Electronic biosensors? (longer-term) Control measure effectiveness & impact Track & model population-level impacts of snail/bird removal Test ecosystem-level impacts of copper sulfate & alternative molluscicides (surveys/mesocosms, medium-term) Improve predictive models for snail density, trematode prevalence, and cercaria production Spatial & temporal surveys (short-term) Lab & Mesocosm experiments (medium-term) Predictive modeling (medium-term) DEVELOPMENT OF ALERT SYSTEMS (long-term) Test and validate predictions of Aquatox models, used by regulators to help make decisions.

Swimmer’s itch Trematode infection (avian schistosomes) 2-host life cycle (SNAILS) Discourages recreational water use (economic impact) Difficult to manage Limited research literature Limited funding opportunities

What determines swimmer’s itch exposure? Snail population density Percent snails infected Cercariae produced per snail Bird infection Temperature variation Nutrient loading (Eutrophication) Cercariae in water SWIMMER’S ITCH!

Potential Management Strategies Snail control Copper sulfate Mechanical removal Bird control Hunt, relocate, treat Pollution control Protective skin creams Public education Predictive modeling Management decisions Real-time alerts

2015 Summer Research Aims: 1. Temporal surveys: Obtain field data that can be used to validate models predicting short term fluctuations in swimmer’s itch exposure 2. Spatial Survey: Collaborate with volunteers to obtain data from 8 lakes to determine predictors of schistosome cercariae abundance across a region.

1. Temporal survey What are the best predictors of daily abundance of avian schistosome cercariae? Core hypothesis– cercaria production is driven by the thermal biology and dynamic energy budgets of the snail host Alternative predictors– water temperature, wind direction/speed, snail population dynamics, algal growth (food) Temperature Wind speed Snail population Algae

2. Spatial survey What determines patterns of schistosome cercariae production across a broad landscape? Potential predictors: lake size/depth/hydrology Land use & soil/rock types Climate (temp, precipitation, wind) Snail & invertebrate densities Pollutants (pesticides & nutrients) Algae/vegetation growth Bird visitation Nutrients Snail densities Land Use

Methods Lake Volunteers Sample from water surface using 1 liter, 35 µm mesh filters 50 filter scoops along shore  one sample Rinse filters with ethanol to preserve cercariae Sample between sunrise and noon each day Store samples in cool, dark place

Methods Raffel Lab Survey snail populations Pipe-sampling PCR methods qPCR to quantify schistosome DNA in water Regular PCR & sequencing to identify species ELISA kits to detect pollutants Herbicides: triazines & metabolites, glyphosates Insecticides: organophosphates and carbamates Periphyton growth Ceramic tiles chlorophyll extraction Land use characterization GIS software and datasets Water temperature, wind velocity, precipitation HOBO loggers and weather databases

Quantitative/Real-time PCR

Spatial survey 2015: Raffel Lab commitments: Organize survey Provide training and sampling materials Survey snail & invertebrate populations Measure environmental variables Process cercaria DNA & water chemistry samples Statistical analysis, reports, and presentations Lake Association participation: Recruit at least 1 volunteer to collect daily filter samples for 2-4 weeks during July/August Provide financial support to analyze cercaria DNA and water chemistry samples ($500 per site) Help select sampling sites

Timetable Month Goals April Sampling schedule, refine methods, identify study sites May/June Monthly visits to sites to survey and collect data July/August Daily cercaria sampling from lakes known to harbor swimmer’s itch September Process samples, compile data Oct/Nov/Dec Follow-up experiments & analysis