DATA SET IDENTIFIER: Effects of biotic (shrimp) and abiotic (discharge) factors on the depositional environment quantified in a montane stream in Puerto Rico. (Shrimp/Algae/Can J. Fish Aquat. Sci. (1994))

PROJECT TITLE: Influence of Decapods on Ecosystem Processes

PROJECT DESCRIPTION: Three experiments were performed to study the influence of decapods on ecosystem processes. In the first one (catalogued as LTERDBAS #104) the hypothesis that differences in macrobiotic assemblages can lead to differences in the quantity and quality of organic matter in benthic depositional environmentsamong streams in montane Puerto Rico was tested. The experimental results were consistent with findings of an independent survey of six streams in four different drainages. Four streams that had an abundance of omnivorous shrimps but lacked predaceous fishes, had extremely low levels of fine benthic organic and inorganic material. In contrast, two streams that had low densities of shrimps and contained predaceous fishes had significantly higher levels. Results showed a strong linkage between species and ecosystem characteristics: interstream differences in the quantity and quality of fine benthic organic matter resources were determined by the nature of the macrobiotic assemblage. Furthermore, patterns in the distribution of shrimp assemblages reflected landscape patterns in the benthic depositional environment among streams.

In the second experiment (LTERDBAS #105) the role of freshwater shrimp, which dominate the faunal biomass of many tropical headwater streams, was studied. The enclosure/exclosure experiments in a montane Puerto Rican stream the direct and indirect effects of two dominant taxa of atyid (Atyidae) shrimp, Atya lanipes Holthius and Xiphocaris elongata Guerin-Meneville was examined. Both shrimp taxa caused significant reductions in sediment cover on rock substrata, reducing sedimentation and enhancing algal biovolume on clay tiles in cages.We evaluated the mechanism by which A. lanipes influences algae and benthic insects by comparing patterns of algal biomass, taxonomic composition and shrimp-presence treatments both with and without manual sediment removal. The shrimp exclusion treatment without manual sediment removal had significantly lower algal biomass and greater sedimentation than all other treatments. The treatment in which shrimp were excluded but sediment was manually removed, however, accrued almost the same algal biovolume as the shrimp enclosure treatment, supporting the hypothesis that sediment removal enhances the biovolume of understory algal taxa.

The effects of biotic (shrimp) and abiotic (discharge) factors on the depositional environment were quantified in a montane stream in Puerto Rico in a third experiment (LTERDBAS #106). Electricity was used experimentally to exclude large (approximately >1cm in length) biota without artificially increasing sedimentation as in cage enclosure/exclosure experiments in stream systems. Unelectrified control substrata had natural high densities of atyid shrimp. Atyid shrimp can significantly affect the accumulation of organic and inorganic materials on rock substrata in stream pools between high-discharge events.

LTER CORE AREAS: (Annotate all that apply)

Population Dynamics

LEF LTER 1 RESEARCH TOPIC: (Annotate all that apply)

Spatial and Temporal Distribution of Populations

We define a data file as a component of a data set. A data set can have only one data file or more. Basically, different data files have different data structures or format.
DATA SET FILES (SUBSETS):

Data File No.	Data File Identifier	On-Line Filename	Starting Date	Periodicity of sample	End Period
1	Total dry mass of sediment and percentage organic matter in control and electrified shrimp exclusion treatments after 0, 1, 2, 4, 5, and 8 days (Fig2)	fig2.txt	September 5, 1992	once	September 14, 1992
2	Total dry mass of sediment and electrified shrimp exclusion treatments and on rocks located outside the treatments at 6, 12, and 30h following a storm event (Fig3)	Fig3.txt	September 5, 1992	once	September 14, 1992
3	The total algal biovolume for each taxon for the each three sampling of the electro control and the electro exclusion experiments (Fig4)	Fig4.txt	September 5, 1992	once	September 14, 1992

RESEARCH LOCATION: In a shaded pool (approximately 3.5 m length X 2.3 m width) of the Quebrada Toronja

INVESTIGATORS:
PRINCIPAL INVESTIGATORS E-MAIL address

OTHER RESEARCHERS E-MAIL address

Gail A. Blake

CONTACT PERSONS E-MAIL address Phone Number (Include area code)

Catherine M. Pringle

cpringle@uga.edu

(706) 542-1120

SOURCE OF FUNDING (SPONSOR): NSF BSR-91-07772

DATA SET METHODS: Electric exclosure devices were constructed to exclude large (approximately >1 cm) invertebrates from foraging on rock substrata in a shaded pool (approximately 3.5 m length X 2.3 m width) of the Quebrada Toronja. Treatments were designed to either exclude or allow access to shrimp or other relatively large organisms such as crabs and fish. For more detailed methodology see publication.

REFERENCES:

STORAGE SITES: DM Cabinet DM003 Drawer 3

LEF LTER OFFICIAL KEYWORDS (See table): Q TORONJA, RIVER, SEDIMENTATION, DECAPODS, PEER REVIEWED JOURNAL

PUBLICATIONS:
Pringle, C.M., Blake, G.A. (1994) Quantitative effects of atyid shimp (Decapoda: Atyidae) on the depositional environment in a tropical stream: use of electricity for experimental exclusion. Can. J. Fish. Aquat. Sci. 51: 1443-1450

DISSEMINATION: UNRESTRICTED

REASONS TO RESTRICT DATA IN THIS DATA SET BEYOND ITS TWO YEAR POLICY PERIOD*:

*WILL HAVE TO BE APPROVED BY LTER PRINCIPAL INVESTIGATORS: N. BROKAW, A. LUGO

SITES DESCRIPTIONS: The experiments were carried out in pools of the stream Toronja. 32cm in diameter rings were placed in the stream. The control hoops were not electrified while the exclusion hoops were.

Geographical positional system (GPS) Coordinates for each location:

location	latitude	longitude
Shaded pool (approximately 3.5 m length X 2.3 m width) of the Quebrada Toronja

VARIABLES (ATTRIBUTES): ALGAL_BIOVOLUME_G-M2

FILE NAME OR #ABOVE (all in which the variable appears)	1,2	1	1,2	1	1
ABBREVIATION (as it appears on the data file)	TREATMENT	DAY	ALGAL_BIOVOLUME_G-M2	TOTAL_MINERAL_G-M2	TOTAL_ORGANIC_G-M2
NAME OF VARIABLE	Type of treatment	Sampling date	Weight of total algal biovolume	Weight of total mineral content	Weight of total organic content
DEFINITION OF VARIABLE	States whether it is a control or a electro exclusion experiment. No data is missing for this field.	The day which the sampling took place. No data is missing for this field.	States the weight of total algal biovolume in g/m2 for a defined area. If the same sites and similar sampling methods are employed the experiment should be replicable. No data is missing for this field.	States the weight of total mineral content for a defined area. If the same sites and similar sampling methods are employed the experiment should be replicable. No data is missing for this field.	States the weight of total organic content for a defined area. If the same sites and similar sampling methods are employed the experiment should be replicable. No data is missing for this field.
UNIT			gramsPerSquareMeter	gramsPerSquareMeter	gramsPerSquareMeter
PRECISION
RANGE OR LIST OF VALUES	{control, exclusion}	{0 ,..., 8}	{0,..., 681.0}	{0 ,.., 974.8}	{0.9,..., 156.8}
DATA TYPE	alphanumeric	integer	real	real	real
MISSING DATA CODES

VARIABLES (ATTRIBUTES):

COMPUTATIONAL METHODS:

Variable Name	Formula

FOR DATA MANAGER USE ONLY

DATE OF LAST REVIEW: April 9, 2009
DATE OF LAST ENTRY: September 14, 1992
STAGE OF DATA SET MANAGEMENT (dates):
RECEIVED: June 2000
ENTERED: FILED July 2000
ON-LINE: October 2000
REVIEWED BY RESEARCHER
FILING MEDIA: magnetic media only
NAME OF DOCUMENTATION FILE:  lterdb106.htm
NAME OF DATA FILE: Fig#.txt;
NAME OF ON - LINE CATALOG :LTERDBAS
RECORD #: 106
DOCUMENT TYPE:
PRIORITY TO BE ENTERED: N/A

Rev. date of this form: 8 June 2001