presented by rachel barlow

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