The Salt River, an intermittent stream that runs from the highest peak, Blue Mountain, to the mangrove wetlands, and out to fringing reef provides an excellent setting for student study.

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One of the first activities will be to determine the slope of the river.  This can be done by marking the distance between the evaluation lines on a topographic map (see U.S. Geological Survey).  A small magnifying glass helps make these measurements.  For a step by step description see Robert Ford's Activity 2: How to Make a Topographic or Stream Profile.

The next step is to start at the headwaters and walk down the length of the river.  The trip would be for observation and recording purposes, noticing changes in vegetation, soil, the slope of the river, erosion, or other aspects of the river's course.  An expansion of this activity would be to collect soil samples along the length of the river, recording the sites and conditions of the sample site.  Soil comparison could be at the elementary level, looking for particle size and general make-up of the soil.  At the middle school level or high school levels, the sophistication of observations could be improved, for example, taking pH of soils, or moisture content.  See, for example the GLOBE program protocols for soils.

On future trips transects could be set up to determine the type and density of the vegetation at various places along the stream.  There are several Internet sites which describe these activities, including the GLOBE Program Land Cover/Biology Investigation and Outward Bound.  Equipment is simple and each team would need a couple of meter sticks, a tape measure, and a length of rope.

Another activity would be to take water samples, observing turbidity, pH, dissolved oxygen, nitrates, and other chemical tests. Again, the GLOBE Program Hydrology Investigations offers activities for K-12 students testing water samples.  Students could, for example, notice turbidity differences before and after a rain.

Description of the Salt River

Mangrove Wetlands

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At the mouth of the river are the mangrove wetlands.  The mangroves (see Documents, "Mangroves") provide a natural filter to trap particulate matter in the run-off water.  The roots provide shelter for developing fish and provide nutrients to algae and fungi. Thus, the mangroves are called the nursery of the sea.

Coral Reefs The following picture of St. Croix, from the NASA Shuttle, shows the fringing reef as a pale blue, surrounding the island and Buck Island.  A wealth of information about the reef can be found in the work of Paul Blanchon, from Indiana University.

Queen Angle    http://www.coralreef.org/res2/sm-creef15.jpg

BlueTang    http://www.coralreef.org/res2/sm-creef20.jpg

Three activities can be done to determine the density and diversity of organisms.  First, collect the three types of seaweed/algae: red, green, and brown.  Students can take them to the lab and identify them, then press them in the same manner as leaves are pressed, between wax paper, with a heavy weight added.

The next two activities involve the marking of quadrants on sandy, rocky, and muddy shores.  First, establish one meter square quadrants for recording and observational purposes (Hula Hoops® could also be used to bound the student observation locations.  Students will count and record the number and types of organisms found in that quadrant.  Second, the same procedure can be used in the grass beds.  (There are three types of sea grass in St. Croix:  shoal grass; manatee grass; and turtle grass.)

Off-Shore Activities

The marine students who are scuba divers can monitor a coral reef throughout the year.  The procedure requires two reinforcement bars and a ten meter chain.  The chain is suspended above the reef, being careful not to touch the reef, using the reinforcement bars to suspend the chain.  Students will then look through each link to determine and record the type and condition of the coral beneath that link, noting whether the coral is thriving or dead.  In this way, the vitality of the reef can be monitored from year to year.  Unfortunately, most reefs around the world are declining.  This activity will encourage the students to assume stewardship of the reefs.