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Study to Refine Comal Springs Riffle Beetle Collection Methods and
Establish Riffle Beetle Population Distribution
Presented by Rachel Barlow
According to the EAA Request for Proposals (RFP) for this study:Comal Springs riffle beetle (CSRB) distribution is currently
unknownCSRB collection methods can be improved
Per the RFP, this study is intended to:Establish a distribution of springs serving as CSRB habitatTest the success rate of at least three collection methodsCollect CSRB for use in other 2014 Applied Research studies
425 mapped springs in Landa Lake and the Comal System (Norris and Gibson 2013)
Currently Understood CSRB Distribution within the Comal System
Western shorelineOff northeastern tip of Spring IslandBetween western shoreline and northernmost peninsula
of Pecan IslandSpring runs 1-3
BIO-WEST 2002
BIO-WEST 2002
Previous Collection Methods
Fingers and/or soft forcepsDip netsCotton cloth luresCotton lures inside PVC
tubingDrift net sampling
Cotton cloth lure allowed to “culture” in situ for a period of four weeks
Study ObjectivesTest the success rate of three lure typesEstablish CSRB distribution within the Comal System
Methodology
Preliminary trials with surrogate speciesCollect 250 CSRB (maximum)Store in aquaria
Beetle Collection and Housing
Methodology (con’t)
Four experimental chambers- Three test systems- Control
Treatments (24 hour test cycle x 3)- Cotton cloth lure- Lighted cotton cloth lure - Hemp cloth lure
50 CSRB per chamberExpected results and analysis
- % CSRB captured per test cycle- ANOVA (lure type)
Laboratory Experimental Design
Methodology (con’t)
Adaptive sampling- Only sample springs with CSRB habitat- CSRB present, move on
Exclude springs with known CSRBUse most effective lure realized in laboratory studySurvey (check traps) up to 3 times Survey no more than twice weekly
Population Distribution Study
CSRB Habitat Criteria(based on physical parameters measured by Norris and Gibson 2013)
Spring type: upwellingTemperature: 68-75°FSubstrate consisting of organics, sand, course sand,
very small gravel, small gravel, medium gravel, rubble, small cobble, and large cobble
Flow sufficient to maintain clear substrate conditions
Expected Results
Tested collection methodUpdated map of CSRB distributionAnimals per trap across spring orificesExamination of other contributing parametersNumber of surveys leading to presence/absence
determinationNature of changing spring locations in relation to
presence/absence studies