Belleisle Marsh, Floodplain or Estuary? EarthCache

Belleisle Marsh, Floodplain or Estuary?

The Annapolis river measures 120 kilometres in length, and meanders southwest through the western part of the valley from its source in Caribou Bog (50 m [160 ft] above sea level) near the villages of Aylesford and Berwick in western Kings County, to its mouth at Port Royal where it empties into the Annapolis Basin. The estuary portion of the Annapolis River runs from Bridgetown to Port Royal and experiences a tidal range of approximately 7.5 m (25 ft) between tides every twelve hours.

One of the largest estuary areas along the river and within the tidal range, is known as the Belleisle marsh. The estuary consists of 700 acres along one of the S-bends in the Annapolis river. About 171 acres is managed as wetlands habitat, 333 acres are managed as upland habitat while the remaining 196 acres is being used for agriculture. The estuary is managed with a goal to demonstrate that the needs of both people, wildlife and water purification can be met.

Floodplains

A floodplain is an area of land which is covered in water when a river bursts its banks. They form due to both erosion and deposition. Erosion removes any interlocking spurs, creating a wide, flat area on either side of the river. During a flood, material being carried by the river is deposited (as the river loses its speed and energy to transport material). Over time, the height of the floodplain increases as material is deposited on either side of the river. The floodplain is often a wide, flat area caused by meanders shifting along the valley.

Estuaries

An estuary is where the river meets the sea where they store carbon, filter water, buffer against storm  events, stabilize the coast, and are home to many species of plants, fish, and wildlife. The Annapolis river is tidal at this location and when the sea retreats the volume of the water in the estuary is reduced. When there is less water, the river deposits silt to form mudflats which are an important habitat for wildlife.

Estuarine circulation serves a valuable, ecological function. The continual bottom flow provides an effective ventilation system, drawing in new oceanic water and expelling brackish water. If it weren’t for this natural “flushing” process, the waters of the estuary would become stagnant, pollution would accumulate, and oxygen would be depleted.

This circulation system leads to incredible ecological productivity. Nutrients and dissolved oxygen are continually resupplied from the ocean, and wastes are expelled in the surface waters. This pumping action leads to some of the highest growth rates of microscopic plants (researchers call it “primary production”) in any marine environment.

What makes the Belleisle Marsh unique?

Sections of the Belleisle Marsh are part of the floodplain for the Annapolis river. It was formed from years of deposition and fresh water flow of the river that created great meanders along the river. The floodplain contains a lot of fresh water brooks as well as grasses, rushes, reeds, Typha {cat tails}, sedges, and other herbaceous plants (possibly with low-growing woody plants) in a context of shallow water.

Along the edges of the Belleisle marsh there are a number of inlets where salt tidal water floods the marsh twice a day, leaving an estuary that is brackish. Estuarine marshes often are based on soils consisting of sandy bottoms or bay muds. Estuaries are dominated by dense stands of salt-tolerant plants such as herbs, grasses, or low shrubs. These plants are terrestrial in origin and are essential to the stability of the salt marsh in trapping and binding sediments.

Even being so far up river (20 km) there is still a tidal impact on the Belleisle marsh which provides a flush of both fresh and salt water to the estuary twice a day. The water of this marsh can be fresh, brackish or saline depending on the section or area that you visit, along with the time of day for the tidal event. Even part of the upper marsh has been drained for agriculture use.

To log this Earthcache visit the viewing location.  Please answer the following questions and send in a timely manner to my geocaching profile or email. Answers not received will result in deleted logs.

Questions:

1. At ground zero, what three activities occur on the Belleisle marsh? (read sign)

2. What came first, the flood plain or the salt estuary and why?

3. What feature is behind the sign at ground zero and using features of soil explain why it is needed?

4. How will climate change impact Belleisle marsh and estuary?

5. Post a picture in your log with a personal item or hand in picture to prove you were there.

[REQUIRED] In accordance with the updated guidelines from Geocaching Headquarters published in June 2019, photos are now an acceptable logging requirement and WILL BE REQUIRED TO LOG THIS CACHE. Please provide a photo of yourself or a personal item in the picture to prove you visited the site.