d.a. kikkert, t.a. crowl, and a.p covich
DESCRIPTION
Physical and chemical factors affecting the upstream migration of amphidromous shrimp in the Luquillo Experimental Forest. D.A. Kikkert, T.A. Crowl, and A.P Covich. MIGRATION. Persistent, undistracted movement from one habitat to another at specific life stages (sensu Dingle 1996). - PowerPoint PPT PresentationTRANSCRIPT
Physical and chemical factors affecting the upstream migration of amphidromous shrimp in the Luquillo Experimental Forest
D.A. Kikkert, T.A. Crowl, and A.P Covich
Persistent, undistracted movement from one habitat to another at specific life stages (sensu Dingle 1996).
Among aquatic biota the best studied migrations are those of diadromous fishes such as salmonids and eels.
MIGRATION
DIADROMYMIGRATIONS BETWEEN MARINE AND FRESHWATER
ENVIRONEMNTS AT PARTICULAR LIFE STAGES (MYERS 1949)
AMPHIDROMY
ANADROMYSPEND MAJORITY OF LIVES IN THE SEA, MIGRATE INTO FRESHWATER TO BREED
CATADROMYSPEND LIVES IN FRESHWATER, MIGRATE TO THE SEA TO BREED
AMPHIDROMY
Migration between fresh water and sea for purpose other than breeding
•Migration usually occurs during the larval life stage
•Most common on tropical oceanic islands where it may be necessary for dispersal.
Freshwater
Ocean
Adults
Larvae
LarvaePost Larvae Adults
Luquillo Experimental Forest (LEF)
•Humid, subtropical climate
•Annual rainfall ranges from 1000 to 6000mm
•Slightly seasonal with a dry season from February-April
•Nine streams originate within the LEF
Luquillo Experimental ForestSTREAMS
• Headwater streams characterized by steep gradient (10-20%)
• Primarily boulder and cobble lined with bedrock glides and waterfalls common
• Discharge is highly variable with flows increasing rapidly during rainfall
Luquillo Experimental ForestSTREAMS
Luquillo Experimental ForestSTREAMS
Espiritu Santo Discharge 8/ 20/ 05
0.00
500.00
1000.00
1500.00
2000.00
2500.00
3000.00
3500.00
4000.00
4500.00
5000.00
800 1000 1200 1400 1600 1800 2000 2200 2400
Time
Dis
ch
arg
e (
cfs)
8/20 800-2350
SHRIMP
• Headwater streams dominated by 2 species of atyid shrimp (Xiphocaris elongata and Atya spp.) and the freshwater prawn Machrobrachium spp.
• Adult populations in headwater streams are well studies as part of an NSF long term monitoring program
• Little is known about the upstream migration of post-larvae
UPSTREAM MIGRATION• Nocturnal migration
• Hypothesized increase in migration during times of low predation risk
• Critical for recruitment into adult populations
• Increasing human development in the coastal plain
• Road / stream intersections could act as barriers (Biocomplexity project)
UPSTREAM MIGRATION
OBJECTIVES
• Quantify upstream migration of Xiphocaris elongata, Atya spp., and Macrobrachium spp.
• Identify regular patterns in shrimp migration rates
• Identify environmental factors that may affect upstream migration
METHODS
FIELD STUDY ARTIFICIAL STREAMS
FIELD STUDY
• Sampled shrimp migration over 5 months (N=46 nights)
• Used multiple regression to determine if environmental variables explain variation in shrimp migration rate and timing
RESULTSSHRIMP MIGRATION RATES
-200
0
200
400
600
800
1000
1200
ALL SHRIMP Atya spp. Xiphocaris elongata Macrobrachium spp.
SH
RIM
P/
HO
UR
AverageMaxMin
RESULTS
Atya spp. F=3.18 p=0.07Xiphocaris elongata F=12.77 p=0.0005Macrobrachium spp. F=24.86 p=0.0001
DRY SEASON SAMPLING (N=12)
WET SEASON SAMPLING (N=34)
RESULTSREGRESSION
ENVIRONMENTAL VARIABLESCLOUD COVER (0-1)
PERCENT MOON ILLUMINATED
MOON PRESENCE/ABSENCE
OBSERVED MOONLIGHT
MOON POWER (% ILL.*P/A*CLOUD COVER*TIME SINCE MOONRISE)
PRECIP (IN)
PREVIOUS DAYS DISCHARGE
INSTANTANEOUS DISCHARGE
MEAN DISCHARGE (PREVIOUS 24 HOURS)
CV DISCHARGE (PREVIOUS 24)
NUMBER OF FLASHFLOODS / WEEK
TIME SINCE LAST FLASHFLOOD
TIME SINCE 1% EXCEEDANCE FLOOD (Q323)
TIME SINCE 25% EXCEEDANCE FLOOD (Q23)
RESULTSREGRESSION Atya Spp.
MODELPARAMETER ESTIMATES AIC (∆i ) r2 Adj r2 N
CLOUD COVER 3.9065 0 0.3527 0.3104 117
MOON POWER -0.0395
PRECIP 10.8802
CV (Q) 1.1328
FF / WEEK -1.84292
TIME SINCE FF -0.0178
TIME SINCE 1% EXCEEDANCE FLOOD
0.0103
RESULTS REGRESSION Xiphocaris elongata
MODELPARAMETER ESTIMATES AIC (∆i ) r2 Adj r2 N
ORDINAL DAY 0.00606 0.6169 0.2944 0.2629 118
CLOUD COVER 0.02759
PRECIP -1.1342
TIME SINCE Q323 -.0005
TIME SINCE Q23 0.0014
RESULTS REGRESSION Xiphocaris elongata - WET SEASON ONLY
MODELPARAMETER ESTIMATES AIC (∆i ) r2 Adj r2 N
Q INSTANTANEOUS -0.01098 0.16030.275
00.2452 77
MEAN DISCHARGE -0.00709
NUMBER OF FF / WK 0.14845
RESULTS REGRESSION Macrobrachium spp.
MODELPARAMETER ESTIMATES AIC (∆i ) r2 Adj r2 N
ORDINAL DAY 0.00834 0 0.6596 0.6444 118
CLOUD COVER 0.45092
PRECIP -3.40863
PREVIOUS DAYS Q 0.00275
TIME SINCE Q323 0.000599
RESULTS REGRESSION Macrobrachium spp. - WET SEASON ONLY
MODELPARAMETER ESTIMATES AIC (∆i ) r2 Adj r2 N
ORDINAL DAY 0.01351 1.06640.712
60.6964 76
OBSERVED MOONLIGHT 0.36332
PRECIP -2.20734
Q INSTANTANEOUS -0.00967
ARTIFICIAL STREAMS
ARTIFICIAL STREAMS
TREATMENTMETHOD
(APPLIED TO ONE SIDE OF EACH STREAM)
PREDATOR PRESENCE/ABSENCE
FISH (MOUNTAIN MULLET)
INCREASED FLOW INCREASE INSTANTANEOUS Q
TURBIDTY SEDIMENT ADDED
LEAF LITTER CONDITIONED LEAF PACKS
RESULTS ARTIFICIAL STREAMS Atya spp.
Atya spp.
0
0.20.4
0.60.8
1
CONTROL
FISH P
/A
FISH *
2
FLOW
TURBIDIT
Y
LEAF LI
TTER
TREATMENT
PR
OP
OR
TIO
N
NO
TREATMENT
* **
*
* DENOTES SIGNIFICANCE AT P=0.05
RESULTS ARTIFICIAL STREAMS Xiphocaris elongata
Xiphocaris elongata
0
0.20.4
0.60.8
1
CONTROL
FISH
FISH*2
FLOW
TURBIDIT
Y
LEAF LI
TTER
TREATMENT
PR
OP
OR
TIO
N
NO
TREATMENT
* **
* DENOTES SIGNIFICANCE AT P=0.05
CONCLUSIONS• Atya spp. make up majority of shrimp migration
• Xiphocaris elongata and Macrobrachium spp migrations seasonal
• Macrobrachium make up a large component of the shrimp migration in August
• Ayta spp effected by light levels and flow regime with increased migration following spates
• Xiphocaris and Macrobrachium spp. migrate during periods of low
• Migration rates of all species decrease during extended periods of low flow
CONCLUSIONS
• Atya and Xiphocaris avoid channels with possible low water quality (turbidity and leaf litter)
• Spates may increase water quality and shrimp migration
• Chemical cues from fish predators may play a role in shrimp migration
• Atya appear to be positively rheotactic, following the highest flow
Acknowledgments• Todd Crowl• Katie Hein• Alan Covich• Wyatt Cross• Ecology Center
(Utah State University)
• Ruth Kikkert (All the fieldwork)