Salado Salamander Monitoring

Transcription

1 Salado Salamander Monitoring Peter Diaz Randy Gibson and Valentine Cantu Texas Fish and Wildlife Conservation Office San Marcos Aquatic Resource Center San Marcos Texas San Marcos Texas

2 Eurycea chisholmensis Described by Chippendale et al Designated Threatened by FWS in 2014 Range has been expanded due to new genetic analysis (Hillis et al. 2015; Section Six Grant) Hillis et al. 2015

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4 Monitoring Goals FY 2015 Occupancy surveys at spring sites Measures of abundance for adults and juveniles Habitat associations within each site and habitat availability per site Contaminants within water Surface recruitment Sample openings for prey base of aquifer invertebrates

5 Occupancy Surveys Transect surveys done at Big Boiling, the Benedict/Anderson spring run, and at Robertson Occupancy = presence at a site During surveys: one salamander found within framework of survey Four others found during opportunistic sampling Two from Big Boiling (April 1, May 14) One from Robertson (July 16) One from Anderson (Sept. 11)

6 Probability of Detection for Big Boiling Detectability = aspect of sampling Presence program used for analysis Naïve occupancy score = Calculated occupancy score of 1.0 Probability of detection of Therefore, model is stating that the salamanders are present within the spring, just very difficult to detect.

7 Where Have Salamanders Been Found Location Date Transect (m) Size (mm) Primary Substrate Secondary Substrate Vegetation Big Boiling 4/1/ Cobble Gravel Ludwigia Big Boiling 4/8/ Gravel Sand None Big Boiling 5/14/ Gravel Sand Filamentous Algae Robertson Spring 7/16/2015 Drift Net 0 14 NA NA NA Anderson Spring 9/11/ Gravel Cobble Filamentous Algae Robertson Spring 10/2/2015 Drift Net NA NA NA Robertson Spring 10/2/ Silt Gravel Detritus All captured salamanders tracked individually using Wild ID program. All occurrences sent to TXNDD for documentation

8 Habitat Availability Big Boiling (114 ft 2 ) Substrate Category Count Percentage Silt/Mud Sand Gravel Cobble Boulder Bedrock Robertson Spring (141 ft 2 ) Substrate Category Count Percentage Silt/Mud Sand Gravel Cobble Boulder Feet Meters

9 Contaminant Analysis Semipermeable membrane devices deployed at Robertson Spring and at the Stage Coach Inn cave Deployed for 49 days Samplers have been sent off to be analyzed PCB, PBDE, Organochlorines, PAH

10 Potential Surface Recruitment Drift nets left on the largest orifices at Robertson Spring in order to determine frequency of salamanders leaving the underground environment to the surface Net was on for four consecutive weeks during high discharge from springs (30 days) twice for a total of eight weeks Two salamanders have been caught one on each event salamanders per day Big Boiling effort ~ 20 hrs of netting Little Bubbly effort ~ 10 hrs of netting

11 Aquatic Invertebrates as Prey Base Many new county records for phreatic or hyporheic aquatic invertebrates Very productive system

12 Future Efforts Examine relationship between drift rate of aquatic invertebrates and surface populations of Eurycea salamanders Capture microhabitat data on salamander habitat associations for long term data set Monitor other openings for data to populate surface model of recruitment Do occupancy study within the creek to look for salamanders Examine options for refugium on site/off site Continue 2015 efforts to collect long term data set

13 Other Places with Listed Salamanders San Marcos Springs Comal Springs Barton Springs High levels of recreation Municipalities maintain autonomy Conservation measures in place