Study Area

The Island of Isabela provides habitats to hundreds of species of flora and fauna. Many of the species that habitat Isabela are unique to this island and rely on Isabela’s fragile mangrove ecosystems. Isabela is also one of the most volcanically active islands in the world with two of the six volcanoes on the island lying directly on the equator and five of the volcanoes still active. The majority of the human habitants of Isabela live in the southern part of the island in the town of Puerto Villamil, where fishing, farming, and especially tourism thrive. Tourism plays a large role in aiding to the local economy in Puerto Villamil and to the development of new infrastructure. With development growing, fragile habitats have been destroyed and are becoming increasingly threatened.

Mangrove Mapping in Puerto Villamil, Galapagos, EcuadorDana Walker, Santiago Lopez

May 2014

Methods and Data

For our first map, we looked at data taken from study abroad students from the University of Washington about the various species of mangrove trees located in Puerto Villamil. We specifically looked at the locations of four different types of mangrove: jeli, (Cibicaroys Erectus) white, (Laguncularia Racemosa) red, (Rhizophora Mangle) and black (Avicennia Germinans) (figure 2). We then digitized polygons in order to distinguish between different types of land cover within town limits. This allowed us to determine which area of the town we needed to focus on. We separated areas of lava rock, mangrove, beach, shore, and infrastructure (figure 3). Next, we took a more detailed look at the area of town that contained the most amount of mangrove (figure 4). In order to do this, we applied unsupervised iso-data classification to distinguish between mean brightness levels of the image that corresponded to land use and land cover types present. By applying an unsupervised iso-data classification to our data, the software was able to alter the brightness levels of each pixel. In the first step of the process, each pixel is compared to five hypothetical categories of mean brightness and assigned to the category closest to it. During the second step, a new mean is calculated for each cluster based on its spatial location on the image. This process continues until the maximum number of changes can be made (figure 6). Once the image was broken down into 100 values of brightness, we were able to manually separate these values into five categories of land cover types. (figure 4 and figure 5). This process was pivotal in allowing us to create our last map, where we were able to quantify the percentage of mangrove evident in each parcel of town (figure 7). This final map shows us which areas of town would be most affected by future development based on mangrove extent.

Introduction

For this project, we want to quantify the extent of mangrove at the parcel level that could be threatened by future development in Puerto Villamil. We created four different maps that have helped us identify the location of different types of vegetation within the town. One of the maps we created helped us identify four different types of mangrove that reside in Puerto Villamil (Figure 2). From this data we were able to visualize where mangrove was most extensive and diverse. Another map we created helped us identify different land cover types within the town limits. We generalized areas of lava rock, grass, mangrove, water, and infrastructure in order to narrow down our specific area of interest (figure 3). These two maps helped us decide to focus our analysis in the south eastern part of town where mangrove is most prevalent and diverse.

Figure 4 Figure 5

Results and Conclusion

In the southeastern part of town we can see that the mangrove extent has a high percentage in between 51% and 100% (figure 7). We can also note that this area inhabits all four categories of mangrove prevalent on the island (Figure 3). This being said, we can assume that developing infrastructure in this area of town would inhibit all four of the mangrove species from growing and surviving. If landowners can prevent development in these areas, mangrove would continue to thrive as crucial and unique habitats for endangered species.

Abstract

Puerto Villamil is one of the largest and most visited towns in the Galapagos Archipelago. The residential population as well as the tourism industry started to increase in the 1990s in Puerto Villamil, which has caused the town to grow immensely with new infrastructure. With development on the rise, it is crucial to understand the need to preserve the fragile ecosystems that constitute the unique environment of the Galapagos. Mangrove areas in Puerto Villamil provide habitats for many endangered species unique to the Galapagos, therefor mangrove conservation is pivotal for their survival. For this research project, we used geographic information systems and remote sensing analysis to create various maps that helped us analyze where distinct mangrove habitats are most prevalent. We found that approximately 7 hectares of town are mangrove areas, mostly residing in the southeastern part of Puerto Villamil. These areas of town should not be developed based on their high extent of mangrove. Our research will help the Galapagos National Park Service negotiate land use in this area of town with municipality in Puerto Villamil.

Unsupervised Isocluster map created to distinguish between land cover in southeastern Puerto Villamil. Cartographic Design by Dana Walker.

This graph was derived from the map in figure 3. It displays land cover areas in hectars in south eastern Puerto Villamil.

Figure 7

Figure 6Isodata involves a remote sensing application used to group similar pixels together based on mean brightness levels.

Our final map displays the extent of mangrove present within each parcel owned by municipality in Puerto Villamil. Cartographic Design by Dana Walker.

Sources Cited

"Isabela." Galapagos Conservancy. N.p., n.d. Web. 04 May 2014.

Jensen, John R. Introductory Digital Image Processing: A Remote Sensing Perspective. Upper Saddle River, NJ: Prentice Hall, 1996. 386. Print.

Source map provided by Geoeye 1 multispectral image resolution 2 meters. Coordinate System: WGS 1984 UTM Zone 15 South.

Figure 2Location of four different types of mangrove species apparent within town limits. Data was provided by University of Washington study abroad students and the municipality of Puerto Villamil. Cartographic Design by Dana Walker.

Figure 3

Digitized polygons created in order to distinguish between general landform types in Puerto Villamil. Cartographic Design by Dana Walker.

Study Area

Figure 1The study area of our research project, the town of Puerto Villamil on the island of Isabela..