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Ben Friedel 2014 NSS Presentation
- 1. Multiple Mark and Recapture Population Size Estimates of Stygobromus tenuis potomacus in a Hypotelminorheic Habitat Benjamin D. Friedel, Jonathan Williams and Dr. Daniel W. Fong American University
- 2. Hypotelminorheic Habitats • Hypotelminorheic Habitats - Aquifer fed by subsurface water - Underlain by clay - Surface window found on slopes at “seepage springs”
- 3. Seepage Springs • Seepage Spring – Diffuse percolation of hypotelminorheic groundwater – Key access point to organisms that live in hypotelminorheic environments Seep C
- 4. Stygobromus tenuis potomacus • Freshwater amphipod crustacean • Common to hypotelminorheic aquatic habitats in Washington, DC area (found in seepage springs) • Besides species and habitat description little is known about their basic biology
- 5. Seepage Spring Sites • Two seepage springs (seeps B & C) studied were 5 minutes from campus • Allowed for weekly sampling Washington DC Metropolitan Area
- 6. Seepage Spring Sites • Sampled Seeps B and C only 5.8m apart • Conducted multiple-mark multiple-recapture estimates of Stygobromus population size at both seepage springs – Data shown for weeks 1-16 (02/20/14 to 06/06/14)
- 7. Methods • Weekly sampling of Seeps B and C • 2-3 people collected Stygobromus in a 1x2m area of the seepage spring for 15 minutes • Stygobromus were counted in the lab – Total numbers, ovigerous females and recaptures
- 8. Methods • Marked with neutral red stain – Stained animals in 100mg/L neutral red dye for 24-48 hours before the next week of sampling – After the next week’s collection, stained animals were returned to original habitats
- 9. Neutral Red Marking • Marking with neutral red stains the cuticle and hepatopancreas
- 10. Data Analysis Methods • Schnabel (S) and Schumacher-Eschmeyer (S-E) methods were used to estimate population size (N) – Assumptions • closed population • lasting marks that do not affect capture ability, behavior or survival
- 11. Data Analysis Methods Schnabel Schumacher-Eschmeyer • s=#sample events • Ct= # captured at tth (16th) sample event • Mt= total # marked individuals in pop. During tth sample event • Rt= # recaptures collected during tth sample event
- 12. Seep B Week C R M W1 25 0 W2 21 0 23 W3 18 0 44 W4 20 0 62 W5 18 0 82 W6 25 1 100 W7 14 2 125 W8 22 1 139 W9 12 1 161 W10 24 6 173 W11 20 10 197 W12 20 15 217 W13 9 4 237 W14 13 6 246 W15 18 14 259 W16 20 17 277 Seep C Week C R M W1 19 0 0 W2 33 0 17 W3 20 0 38 W4 17 0 57 W5 21 0 73 W6 23 0 94 W7 31 0 117 W8 46 2 148 W9 24 2 194 W10 28 6 218 W11 26 4 246 W12 46 6 272 W13 29 3 318 W14 49 17 347 W15 30 20 396 W16 40 40 426 Results • Raw Data Example Collected for Chain Bridge Seeps B and C C= # animals collected that week R= # of recaptures collected that week M = Total # of animals marked and released at that week
- 13. 0 0 0 0 0 0 0 2 2 6 4 6 3 17 20 40 -50 -40 -30 -20 -10 0 10 20 30 40 W1 W2 W3 W4 W5 W6 W7 W8 W9 W10 W11 W12 W13 W14 W15 W16 IndividualsCollected Sampling Week Collected and Recaptures 2014 C 0 0 0 0 0 1 2 1 1 6 10 15 4 6 14 17 -50 -40 -30 -20 -10 0 10 20 30 40 W1 W2 W3 W4 W5 W6 W7 W8 W9 W10 W11 W12 W13 W14 W15 W16 IndividualsCollected Sampling Week Collected and Recaptures 2014 B Comparing Recaptures from Seeps C & B
- 14. Seep Estimates 95% Confidence Intervals B- Schnabel 528 426 696 B-SE 448 353 613 C- Schnabel 1002 827 1273 C-SE 820 600 1291 Population Estimates 2014 CB Stygobromus Population Estimates• 2014 - 703 marked and released, 177 recaptured Seepage Springs B and C combined 528 448 1002 820 0 200 400 600 800 1000 1200 1400 B-S B-SE C-S C-SE Population(Individuals) Seep-Analysis Method
- 15. Ovigerous Females 2 0 0 0 2 3 2 2 1 3 4 10 1 2 1 0 -50 -40 -30 -20 -10 0 10 20 W1 W2 W3 W4 W5 W6 W7 W8 W9 W10 W11 W12 W13 W14 W15 W16 IndividualsCollected Week 2014 B 2 12 1 1 10 6 10 15 5 3 11 14 12 20 9 8 -50 -40 -30 -20 -10 0 10 20 W1 W2 W3 W4 W5 W6 W7 W8 W9 W10W11W12W13W14W15W16 IndividualsCollected Week 2014 C 2014 Total Ovigerous Seep B Seep C 33 139 0.19 0.81 Total Collected S B S C 299 482 0.38 0.62 Total Ov/C S B S C 0.11 0.29
- 16. Conclusions • Population dynamics discrepancies between Seeps C and B – Population estimate for Seep C is greater than Seep B – More ovigerous females (overall and proportion of captures) in Seep C than Seep B Total Ovigerous/Total Collected Seep B Seep C 0.11 0.29
- 17. Conjectures • Seeps B and C could be draining two separate hypotelminorheic systems • Seeps B and C could be connected with an environmental preference by Stygobromus for one seep over the other
- 18. Citations • Culver, D.C. The secret world of seeps (PowerPoint slides). Retrieved from http://www.nps.gov/cue/events/seeps_dec2007/presentation_culver.pdf • Drolet, D. & Barbeau, M.A. (2006). Immersion in neutral red solution as a mass-marking technique to study the movement of the amphipod Corophium Volutator. Journal of Crustacean Biology, 26(4): 540-542. • Holsinger, J. (1967). Systematics, speciation and distribution of the subterranean amphipod genus Stygonectes (Gammaridae). Washington, DC: Smithsonian Institution Press. • Krebs,C.J. (1999). Estimating abundance: Mark-recapture techniques. In: Ecological Methodology. 2nd ed. Menlo Park, CA: Benjamin/Cummings. • Pipan, T., Fišer, C., Novak, T., & Culver, D.C. (2012). 50 years of the hypotelminorheic: What have we learned? Acta Carsologica, 41(2-3): 275-285
Editor's Notes
- Just talk about tenuis potomacus, very FEW studies done . Between 6-8mm -use mark recpature technique to get an estimate ofr the population size, very little is known about basic bioogy of most stygobromus species. Talk just about tenuis pototmaucs .
- Maybe add a map pointing out where the seeps and where DC is. Map of USA. We had previous knowledge that stygo ten. Pot. were there. We already knew there were enough to make a mark recapture study amenable.
- Say that you collected with spoons. Normally the water is always flowing in a few mm h20.
- High confidence that we can recognize a recapture from a new capture
- Schnabel and SE
- Maybe put this at the end as supplemental data so if people have questions
- More data now, presented up to 16 weeks. What dates did we start and end? Throw out 2013 data for the whole talk. Delete N column from this chart. Maybe take out ovigerous column and add in raw data from seep C to show that recaptures so that you can delete graphical representation. You should get a higher proportion of recpatures as time goes on and you do see that. Also delete date and say data from 2/20/14-6/06/14
- Explain the graph better. Total height is # of animals caught red= recaptures. Indicate that this is an ongoing project.
- Take out estimates from table and just have 95CI. 528 (95CIs). CI. Also maybe add CI on graph itself. Good overlap on 95%CI with both methods. Take away tenths on vertical axis Taking away 2013 data allows for bigger graph. Put the exact 95% confidence intervals in a small table with estimates. Estimate is this value with this method (agree very well) with a 95% confidence intervals. Group x axis labels to group two B’s and C’s next to eachother
- Even though the schnabel and SE methods are assumptions for closed populations, and that the seepage spring is not a closed population ebcause it connecvted to a possibly large subterannean network of habitats. The more mark recapture events that you do make the giant thing more of a close population. When the ratio of recpatures increases over time you are confident you are getting a closed population. When the ration of recaptures does not get larger. TO do it for real you may have to use a MM- MR method that uses different marks every time. Reiterate what the population sizes are with the 95% confidence intervals. Also reiterate the proportion of ov. Females in each differ. Maybe discuss the possibility of draining 2 habitats or that animals show some preference from one over the other in a microenvironement kind of way. We know have some datat on the basic biology on the organism that can lead to years of additional studies
- What very little physical data on water chemistry we have they are very similar. Also temperature data is very similar except for winter were it fluctuates.