Mapping the Mangroves - MWL

Objective: The objective of the lesson is to expose students to mapping technology, collect data and establish a data base, and apply the data in zonation, colonization studies and comparative analysis of different estuaries.

Introduction

The mangrove mapping application is available for free at the iTunes store  or the Google Play Store.  The mapping application allows one to take photos of mangrove types and organism found in the estuaries, enter information regarding characteristics and behavior, and upload global position data. The collected data becomes part of a database and can serve as a historic reference, or foundational material to study changes in the estuary, zonation patterns, colonization processes, and estuary comparisons. Zonation patterns and colonization processes are easier short-term classroom studies, estuary comparisons are mid-length projects,  where as the historical change and reference would be part of a longer term projects.

Zonation patterns are a particular interest of study when characteristics of mangroves and their adaptive aspects are understood and one can discern the competitive nuances that result in the organization of the different mangrove species. For example; the Red Mangrove is typically found in deeper estuary waters, handles strong currents, and wave action due to the stabilization and anchoring ability of its prop roots, where as the white mangrove is found in the flatter muddy areas where its pneumatophores aid in respiration in shallow flooding tidal waters and anaerobic substrates. 

Objectives

• Students will use mapping technology to collect data on mangroves.

• Students will use gathered data to perform colonization studies and comparative analyses of different estuaries.
  

Teaching Summary

This activity centers on a visit to an estuary to use the mapping application. Kayaks are an excellent way to access the estuary and observe its many facets. Collected data can be used in a variety of different ways. Zonation activities are a way to make use of collected data. The process starts with collection of topographical information and using it to produce a map representing a band that bisects the estuary. Next a cross section of mangroves within the band are identified and marked with the GPS. This information is then superimposed on top of the topographical map. We conclude by looking for patterns within the map and the reasoning behind those patterns. Below is a zonation study with associated questions.

Vocabulary: Zonation, Colonization

Zonation Exercise

Start with a band that bisects the estuary and determine dimensions. Set up an interval across the map and measure water depths at a high tide. Use this information to construct topographical lines to indicate changing depth in the estuary cross section. Once the map is constructed the mapping application can be used to identify and plot positions of mangroves. This map can now be used to observe patterns in mangrove distribution in an estuary based on water depth. Extra layers of complexity can be introduced by including other parameters on the map such as substrate types and current and temperature measurements. Our map can now be used to determine key physical factors as well as mangrove adaptations that determine the distribution patterns. As maps of other estuaries are constructed, comparative analysis studies can be conducted.

Resources

Download the Mapping the Mangroves app at the Apple or Android stores.  

Assessment Questions

Questions:

1. Is water depth a key factor in determining mangrove species distribution? Support and explain.
2. What are some factors to consider when constructing the map that may lead to error? Support and explain.
3. What adaptions determine the growth range of the Buttonwood? Support and explain.

Answers:

1. Water depth could be considered a key factor for mangrove species distribution, particularly for the Red Mangroves and the Buttonwoods. The Red Mangroves occupy the deepest water areas, where as the Buttonwoods are only in the non flooding zone.
2.  Two important factors to consider are care in maintaining proper location when measuring depth, and correct species identification. Error in either of these areas decreases the validity of the map and conclusions that can be drawn from it.
3. The Buttonwood has no adaptations that allow it to survive in periodic submersion in salt water, this limits it to the outer fringes of the estuary. It does have the ability to exude salt from its leaves, which allows it to grow near the estuary.