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MARVIN 2005

Time, personnel, and logistics frequently limit researchers’ ability to design an ecosystem study that obtains enough samples to fully represent the study area. Often, few data points are used to represent trends over long time periods or large geographic areas. This type of "spot-sampling" is inadequate for addressing most of the high-frequency variability inherent in aquatic ecosystems.

In 2000, the Fish and Wildlife Research Institute contracted AMJ Equipment Corporation of Lakeland, Florida, to build a platform that would hold equipment designed to continuously record data to increase sampling resolution. The project was originally funded through a grant from the National Oceanic and Atmospheric Administration (NOAA) Monitoring and Event Response for Harmful Algal Blooms (MERHAB) program. The platform, named the MERHAB Autonomous Research Vessel for In-Situ Sampling, or MARVIN, was designed for a 3-year sampling program in the St. Johns River. Following completion of that study, MARVIN was relocated to the Caloosahatchee River in January 2005.

Like the St. Johns River, the Caloosahatchee River and adjacent watershed is subject to development and urbanization. Persistent harmful algal blooms (HABs) occur in the river and estuary, and nearby coastal areas are sometimes affected by Florida red tides. HABs can be high concentrations of cyanobacteria (blue-green in color), diatoms (brown in color), and dinoflagellates (red tides). MARVIN’s location in the Caloosahatchee River, between the I-75 bridge and the railroad trestle, will allow researchers to monitor water quality parameters associated with discharges from Lake Okeechobee and the surrounding watershed. Biologists are excited about obtaining these high-frequency water quality data so they can better understand how the complex water quality and physico-chemical characteristics of the river and adjacent estuary affect HABs.

MARVIN is solar powered and mounted on a pontoon boat for convenient maintenance and portability throughout Florida. A computer program controls the sampling intervals of the sensors and stores the measurements on a datalogger. MARVIN data are transmitted every three hours to the MARVIN Web site by Geostationary Operational Environmental Satellites (GOES). Various sensors are connected to a flow-through water system that takes discrete water samples from multiple depths. Onboard sensors will measure several variables including relative fluorescence (chlorophyll a), nutrients (nitrogen and phosphorus), water temperature, dissolved oxygen, pH, salinity, and turbidity. MARVIN also records meteorological data including air temperature, precipitation, barometric pressure, relative humidity, and wind speed and direction. Light sensors, mounted both in the air and under the water, will continuously record light reduction in the river due to turbidity, tannins, or HABs. An Acoustic Doppler Current Profiler (ADCP) will measure current speed and direction and also serves as a tide gauge. During weekly maintenance of MARVIN, water samples will be collected to verify instrument readings.

MARVIN data from the Caloosahatchee river can be viewed at http://www.marvindata.org/ .

Unless noted otherwise, all photographs are credited to FWC.