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
Hypotelminorheic Habitats• Hypotelminorheic Habitats
- Aquifer fed by subsurface water- Underlain by clay - Surface window found on slopes at “seepage springs”
Seepage Springs
• Seepage Spring– Diffuse percolation ofhypotelminorheicgroundwater – Key access point to organisms thatlive in hypotelminorheic environments Seep C
Stygobromus tenuis potomacus• Freshwater amphipod crustacean• Common to hypotelminorheic aquatic habitats in
Washington, DC area (found in seepage springs)• Besides species and habitat descriptionlittle is knownabout their basicbiology
Seepage Spring Sites• Two seepage springs (seeps B & C) studied
were 5 minutes from campus• Allowed for weekly sampling
Washington DC Metropolitan Area
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)
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
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
Neutral Red Marking
• Marking with neutral red stains the cuticle and hepatopancreas
Hepa
topa
ncre
as
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
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
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
W1 W2 W3 W4 W5 W6 W7 W8 W9 W10 W11 W12 W13 W14 W15 W16-50
-40
-30
-20
-10
0
10
20
30
40
0 0 0 0 0 0 0 2 2 6 4 6 317 20
40
Collected and Recaptures 2014 C
Sampling Week
Indi
vidu
als
Colle
cted
W1 W2 W3 W4 W5 W6 W7 W8 W9 W10 W11 W12 W13 W14 W15W16-50
-40
-30
-20
-10
0
10
20
30
40
0 0 0 0 0 1 2 1 1 6 10 154 6
14 17
Collected and Recaptures 2014 B
Sampling Week
Indi
vidu
als
Colle
cted
Comparing Recaptures from Seeps C & B
Population Estimates2014 CB Stygobromus Population Estimates• 2014 - 703 marked and
released, 177 recaptured Seepage Springs B and C combined
B-S B-SE C-S C-SE0
200
400
600
800
1000
1200
528448
1002820
Seep-Analysis Method
Popu
latio
n (In
divi
dual
s)
Ovigerous Females
W1 W2 W3 W4 W5 W6 W7 W8 W9 W10 W11 W12 W13 W14 W15 W16-50
-40
-30
-20
-10
0
10
20
2 0 0 0 2 3 2 2 1 34
10
1 2 1 0
2014 B
Week
Indi
vidu
als C
olle
cted
W1 W2 W3 W4 W5 W6 W7 W8 W9W10
W11W12
W13W14
W15W16
-50
-40
-30
-20
-10
0
10
20
2
12
1 1
10 610
15
53
1114 12
20
9 8
2014 C
Week
Indi
vidu
als C
olle
cted
2014 Total OvigerousSeep B Seep C
33 1390.19 0.81
Total CollectedS B S C
299 4820.38 0.62
Total Ov/CS B S C
0.11 0.29
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
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
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
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