Current Research
in
Puerto Rico is funded by the NSF-Luquillo LTER Project and the USDA
Forest
Service and focuses on: (1) Effects of dams on stream ecosystem
properties
via extirpation of migratory shrimps and fishes (dissertation research
of Effie Greathouse; see first abstract below); (2) a GIS-based
water
budget for the Carribbean National Forest (MS thesis research of Kelly
Crook; see second abstract below) and; (3) headwater-estuarine linkages
(dissertation research of Katherine Smith; see summary below).
DO SMALL-SCALE
EXCLOSURE/ENCLOSURE
EXPERIMENTS PREDICT EFFECTS OF
MIGRATORY FISH
AND SHRIMP EXTIRPATIONS IN PUERTO RICO STREAMS?
Paper presented at the Annual Meetings of the North American Benthological Society, June 2004, Vancouver.
E. A. Greathouse, C. M. Pringle, W. H. McDowell and J. G. Holmquist.
Previous research in Puerto Rico has shown: (1) large dams cause dramatic declines in upstream populations of migratory fishes and shrimps; (2) experimental exclusion of fishes and shrimps increases benthic resources (epilithic algae, fine particulate organic matter, fine particulate inorganic matter, carbon, nitrogen and C:N ratio). Our first objective was to document whether fish and shrimp losses in high elevation rivers upstream from large dams are associated with the types of ecosystem alterations observed in small-scale exclusions. We measured the above benthic resources in 7 dammed rivers and 10 rivers without large dams. Our second objective was to examine whether small-scale field experiments predicted effects of large-scale shrimp and fish losses from pools. We conducted exclusion experiments in 2 rivers without large dams and shrimp addition experiments in 2 dammed rivers. Rivers upstream from large dams had significantly higher epilithic chlorophyll a, FPOM, FPIM, C and N in pools. C:N in pools did not differ significantly between river types. In riffle habitats, epilithic FPIM was significantly higher in dammed rivers, but chlorophyll a and FPOM did not differ significantly. For these parameters, small-scale pool experiments accurately predicted the effects of large-scale shrimp and fish losses.
GIS-BASED
WATER-USE
BUDGETS FOR THE LUQUILLO EXPERIMENTAL FOREST, PUERTO RICO
Paper presented at
the Annual Meetings of the North American
Benthological
Society,
June 2004, Vancouver
Kelly Crook1,
Catherine Pringle1, Fred Scatena2
1Institute
of Ecology, University of Georgia, Athens, GA
2Dept.
of Earth and Environmental Sciences, University of
Pennsylvania,
Philadelphia
PA
Urban development
and
increasing water demand are decreasing freshwater quantity
worldwide.
Problems of water scarcity are not intuitive in a rainforest; however,
dense population surrounding the forest, increasing water demand and
low
water storage capacity are causing concern for the ecological integrity
of stream systems within the Luquillo Experimental Forest (LEF).
The purpose of this project is to determine spatially averaged mean
monthly
water-use budgets for each watershed draining the LEF by combining
long-term
hydrologic data with estimated extraction data into a Geographic
Information
System. Results show that 8.0x108 m3/yr rain falls on the LEF,
32%
of which is lost to evapotranspiration and 68% is converted to stream
runoff.
24% of total annual flow is extracted for human use. This project is a
precursor to further research that will involve hydrologic modeling to
better understand the dynamic between water availability and future
water
demand in order to suggest an optimal scenario of water use which does
not compromise ecological integrity.
MARINE-FRESHWATER
LINKAGES: COMMUNITY COMPOSITION AND DIET OF FISH IN TWO PUERTO RICAN
ESTUARIES
Summary - Ph. D. research
Katherine Smith, University of Georgia
Dams and water withdrawals may affect
marine-freshwater
linkages by reducing freshwater inputs of nutrients, energy, and
organisms.
In addition, water withdrawal may change the physical estuarine
habitat.
A better understanding of the importance of freshwater energy sources
to
estuarine food webs and impacts of dam operations on estuarine health
will
contribute toinforming decisions for inflow management and improving
dam
operation. To study the effects of dams and water withdrawal on
tropical
island estuarine communities I will: (1) quantify the importance and
seasonal
variability of freshwater energy sources to estuarine consumers; and
(2)
examine the impacts of a low-head dam and water diversion structure on
estuarine fish distribution and diet. This study will be
conducted
in two adjacent estuaries of rivers draining the Caribbean National
Forest
(CNF) in eastern Puerto Rico, the Espiritu Santo (dammed) and the
Mameyes
(undammed), which differ in the amount and type of water abstraction.
 Coastal Estuary |
 Leslie Erickson and Katherine Smith |
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