Lotic Breeding Amphibians in the East Bay Regional Park District. Steven Bobzien Ecological Services Coordinator

Transcription

1 Lotic Breeding Amphibians in the East Bay Regional Park District Steven Bobzien Ecological Services Coordinator

2 Acknowledgements Joe DiDonato, Peter Alexander, Neil Fujita, Hal MacClean,, Aileen Theile, and Doug Bell. Sarah Kupferberg Gary Fellers and Patrick Kleeman (USGS) Amy Lind (USFS) Declining Amphibian Population Task Force and Global Amphibian Assessment

3 Research Objectives Determine distribution on District lands Develop a means of monitoring population trends Evaluate and analyze habitat suitability Identify and minimize threats to their survivorship

4 Survey and Research Methods Over 100 stations within 42 streams Used hands, dip-nets and seines to capture all herpetofauna, macro-invertebrates, and other aquatic taxa Gathered data on variety of abiotic and other biotic factors

5 Telemetry Research At Round Valley and Alameda Creeks Capture and release all individuals Inserted pit-tags tags in subadults and adults Used telemetry to track movements and dispersal

6 Lotic Breeding Amphibians

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9 Stream Gradient and Flow

10 Stream Gradient Distribution of Rana draytonii Breeding and Non-breeding (Unconfirmed) Populations STREAM GRADIENT TYPE STREAMS WITH BREEDING N=10 STREAM POPULATIONS WITH UNCONFIRMED BREEDING N=16 Low Gradient Streams <2% 6 5 Moderate Gradient Streams 2-4% 4% 2 2 High Gradient Streams >4-10% 2 6 Extreme Gradient Streams >10% >10% 0 3

11 Rana draytonii Distribution in Various Stream Gradient Types STREAM GRADIENT TYPE Low Gradient Streams <2% STREAMS WITH BREEDING Marsh Creek 0.4% Alameda Creek 1.1% Arroyo Del Valle 1.1% Round Valley Creek 1.5% Alameda Creek 1.7% Sycamore Creek 1.7% STREAM POPULATIONS WITH UNCONFIRMED BREEDING Tassajara Creek 0.6% Dry Creek 0.8% Sinbad Creek 1.6% Tassajara Creek 1.7% Castro Creek 1.9% Moderate Gradient Streams 2-4% High Gradient Streams >4-10% Pine Creek 2.0% Sand Creek 2.8% Altamont Creek 4.7% Brushy Creek 5.5% Dry Creek 2.3% Bear Creek 3.9% Brushy Creek 4.5% Indian Creek 4.7% Marsh Creek 6.4% Markley Creek 6.8% Bollinger Creek 7.1% Arroyo Del Hombre 8.3% Extreme Gradient Streams >10% -----NA NA----- Indian Creek 10.4% San Antonio Creek 13.7% Alameda Creek tributary 21.0%

12 Rana draytonii Distribution in Various Stream Gradients and Types STREAM GRADIENT AND TYPE LOW GRADIENT STREAMS Intermittent Perennial MODERATE GRADIENT STREAMS Intermittent Perennial HIGH GRADIENT STREAMS Intermittent Perennial EXTREME GRADIENT STREAMS Intermittent Perennial NUMBER OF STREAMS WITH BREEDING N= NUMBER OF STREAMS POPULATIONS WITH UNCONFIRMED BREEDING N=

13 Ranid Reproductive Output Gravid R. boylii R. draytonii Amplexus

14 Seasonal Variability of Coastal Streams

15 Flash Flow Mortality

16 Mid March - peak of egg deposition Eggs deposited on vegetation near or at surface Open water edge habitat Eggs hatch within days fecundity unknown Most tadpoles complete metamorphism by Sept. Overwintering tadpoles Rana draytonii

17 Rana boylii Mid April - peak egg deposition period Eggs attached to various substrates Glides, runs and step-pools pools Eggs hatch within days fecundity (mean) Most tadpoles complete metamorphism by Sept.

18 Alameda Creek Water Temperature Data

19 Alameda Creek - Camp Ohlone - Water Temperature and Stream Flow November June 2007 Monthly Monthly mean means Water Temperaure (C) Flow (cfs) Nov-05 Dec-05 Jan-06 Feb-06 M ar-06 A pr-06 May-06 Jun-06 Jul-06 Aug-06 Sep-06 Oct-06 Nov-06 Dec-06 Jan-07 Feb-07 M ar-07 A pr-07 May-07 Jun-07 MONTH AND YEAR WATER TEMPERATURE AND FLOW

20 Alameda Creek Water Temperature and Flow Data 2007 Discharg e ( ft 3 /s) Water Temp erature ( ºC) Daily Mean Discharge Visitor's Center Little Yosemite Camp Ohlone 0 March 22 April 3 April 17 June 15 June 19 June 28 July 23 Sample Date 10

21 Effects of Various Flow Regimes Alameda Creek - Camp Ohlone Rana sp. Reproduction TOTAL NUMBER OF EGG MASSES Rana draytonii Rana boylii Natural Flow Regime YEAR Alameda Creek - Sunol Regional Wilderness Rana sp. Reproduction Irregular Flows Regime TOTAL NUMBER OF EGG MASSES Rana draytonii Rana boylii YEAR

22 Alameda Creek Natural Flow Regimes

23 Alameda Creek Irregular Flow Regimes

24 Alameda Creek Hydrographs Natural Flow Regime Irregular Flow Regime

25 Breeding Season Flow Regimes May 2006 Flow 8.2 cfs May 2006 Flow 355 cfs

26 (a) (b) clutches / km discharge (m 3 sec -1 ) clutches / km discharge (m 3 sec -1 ) 2-year lag recruitment limitation hypothesis /1 6/1 4/1 6/1 Above diversion, near Camp Ohlone near confluence with Calaveras Ck (1 clutch) (1 clutch)

27 Ranid Reproductive Strategies R. draytonii R. boylii

28 Alameda Creek Camp Ohlone Species Rana draytonii egg deposition tadpoles metamorphs Flow Range (cfs( cfs) Rana boylii egg deposition tadpoles metamorphs

29 Reproductive Strategies Attempt to deposit their eggs Delay egg laying Absorb their eggs and skip breeding

30 Discussion Stream systems are highly variable Biotic and abiotic attributes influence amphibians Flow appears to be a limiting factor Irregular flows negatively affect these species Managing flows to mimic natural flow regimes can restore habitat

31 Central Coast Status/Risk Factors Habitat Loss and fragmentation Urban wildlife interface Vineyard conversion Timber Harvest and resulting sedimentation Gravel Mining Non-native native predators or Diversion and Impoundment (Legal and Illegal) Recreation (ATV crossings, Horses, swimmers, dogs)

32 Research Needs for Central Coast Grazing detrimental or not? Genetic distinction among populations Effects of sedimentation Pesticides Chytrid (present but are populations hurt?) Detailed comparison of historical vs extant distribution (give info to Jeff Miller) Juvenile dispersal / telemetry study Make managed salmonid flows compatible with frog needs How to identify appropriate restoration opportunities / mitigation sites --Coordinate with fish passage work

33 Questions?