In the previous lesson, you created an app to share your data with the public. Mapping survey data is useful, but you can also analyze the results to gain greater insight into the location and frequency of whale sightings in the area. In this lesson, you'll add a layer of 2015 survey results to your web map and analyze their spatial patterns. You'll answer the following questions:
- Which protected area had the greatest number of whale, cetacean, and turtle observations during the four-month period when most tours take place?
- How many humpback whale sightings occurred inside the boundaries of protected areas and how many outside?
Your analysis results will help scientists better understand the distribution of whales in the area and whether protected areas support increasing numbers of whales. Your results may increase participation by local guides and captains who have no previous GIS experience. They'll see that by collecting survey data, their contributions lead to a greater understanding of the marine life that visits the Pacific shores of Costa Rica.
Add 2015 whale surveys
After creating your whale survey, you collected three fictitious sightings. You could use these for analysis, but the results would be meaningless with so few records. In this section, you'll update your web map by adding a file containing 76 mock surveys collected in 2015 that will provide more meaningful analysis. In addition, you'll add an updated Costa Rica marine reserves layer that you'll use to summarize the number of sightings within protected and non-protected areas.
- If necessary, sign in to your ArcGIS organizational account.
- In your account's Content page, locate and open your Whale Monitoring web map (not the web mapping application).
Any changes you save to your web map will also be evident in your app. To alter your map without changing the app, you can save a copy of the web map to modify.
- In the Contents pane, turn off the Marine Observations and Parque Nacional Marino Ballena layers by unchecking their boxes.
You'll replace these layers with two layers you downloaded earlier with your XLS form.
- On the ribbon, click Add and choose Add Layer from File.
- In the Add Layer from File window, click Choose File.
- Browse to the Whale_Survey folder, click the Costa_Rica_Marine_Reserves zipped file, and click Open.
This file contains a shapefile of marine reserve boundaries.
- Click Import Layer.
The layer is added to the map. The largest polygon in the layer represents all the territorial waters off the Pacific coast of Costa Rica, while the smaller three polygons represent marine reserves.
Your default symbology might differ from the example image.
- If necessary, in the Change Style pane, under Choose an attribute to show, choose Name.
Each marine reserve will now have a unique color.
- At the bottom of the Change Style pane, click Done.
Next, you'll add the file of whale sightings.
- Click Add and choose Add Layer from File. Import the Whale_Sightings_2015 zipped file.
The sightings are clustered close to the coastline.
- If necessary, in the Change Style pane, under Choose an attribute to show, choose Species.
Each survey point now has a different symbol for each species.
- Click Done.
This layer of whale sightings does not have a configured pop-up like your previous marine observations layer. Pop-ups aren't necessary for analysis, but they provide useful information about specific features.
- Optionally, configure the pop-up for the Whale Sightings 2015 layer any way you like.
- Save your map.
Next, you'll analyze your data to answer two questions. First, you'll determine which protected area had the greatest number of whale, cetacean, and turtle observations during the four-month period these surveys were collected. Second, you'll determine the number of humpback whale sightings that occurred inside the boundaries of protected areas. You'll answer these questions by aggregating observations within specific areas.
- On the ribbon, click Analysis.
- In the Perform Analysis pane, click Summarize Data and choose Aggregate Points.
The Aggregate Points tool takes a layer of points and a layer of polygons and counts the number of points inside each polygon. The tool then creates a polygon layer with the count of points listed as part of the layer's attributes. You'll use this tool to determine the number of observations in each marine reserve.
You can learn more about any analysis tool by clicking the information button (the blue i) next to the tool name.
- If necessary, in the Aggregate points pane, specify the following parameters:
- Choose layer containing points to aggregate into areas: Whale_Sightings_2015
- Choose layer containing aggregation areas: Costa_Rica_Marine_Reserves
Next, you'll decide some statistics for the tool to calculate using the attributes of the whale sightings layer. While the tool will count the total number of observations within each area by default, there are more specific statistics that will improve your analysis. For instance, if you remember your original survey form, it was possible for a single observation to include multiple members of a certain species, such as a herd or family group. Thus, for a more accurate count of species observations, you'll find the sum of the Number field within each observation.
- Under Add Statistics, for Field, choose Number. For Statistic, choose Sum.
Currently, these will be calculated for all points inside the Park boundaries, giving you the total number of observations regardless of species. However, it'll be more useful if you can group the counts by each species. You'll also add percentages so you can compare the proportion of species observations.
- For Choose field to group by, choose Species. Check the box for Add percentages.
- For Result layer name, type Observations by Area. To make the layer name unique, add your name or initials to the end.
New items created by analysis operations must have unique names within your ArcGIS Online organization. Once the layer has been created, you can rename it in your map.
By default, the analysis will only include features in the current map extent. However, some of the marine reserves features extend beyond the current map extent.
- Uncheck Use current map extent.
- Click Run Analysis.
After a few moments, your Observations by Area layer is added to both the map and the Contents pane. A corresponding stand-alone table is also added. The result layer is symbolized as polygon outlines, each with a point in the center. The size of the point represents the count of aggregated observations. At a glance, the Marino Ballena park seems to have the highest aggregated count of points.
The default symbology is difficult to read, however. You'll change it to better visually represent the data and to correspond with the total number of species, not the number of survey responses.
- For the Observations by Area layer, click Change Style. For Choose an attribute to show, choose Sum Number.
When you change the attribute, the symbology changes to a gradient color pattern, where darker colors have more species observed. A legend is added to the map, which indicates that the highest number of observed species is 202, even though your layer had only 76 survey responses. Many surveys reported multiple marine animals.
Next, you'll open the Observations by Area table to see the statistics that the tool generated.
- At the bottom of the Change Style pane, click Done. In the Contents pane, point to the Observations by Area layer and click the Show Table button.
The table contains four entries. The Name field for each of these entries corresponds to a feature in the marine reserves layer. The Costa Rica Ocean Waters feature is not a reserve but represents the Pacific territorial waters of Costa Rica. While the highest count of points is in Marino Ballena (39), the Costa Rica territorial waters have close to twice as many actual species observations (233 compared to 128). However, compared to the two other marine reserves, Marino Ballena has significantly more species observations.
You've answered the first question for your analysis: Which protected area has the most whale, cetacean, and turtle observations? The next question is how many humpback whale sightings occurred within the boundaries of protected areas and how many outside. When you performed your analysis, you also grouped the results by species. You'll examine the grouped results to answer this question.
- In the table, scroll to the right until you locate the groupBySummary column. For the Marino Ballena record (the third record), click Show.
A new table named AggregatedGroupBy opens. This table contains detailed information about the individual animal observations in Marino Ballena (the selected record in the Observations by Area table). The Join ID field of the new table confirms which record the table is for.
The total Count of Points for this table is 39, which also matches the count of points in Marino Ballena.
- In the Observations by Area table, click the Column selection menu button and choose Name.
The table displays the name of the selected marine reserve instead of the ID, making it easier to identify.
Closer examination of the table indicates that most of the observations in Marino Ballena (34) are humpback whale observations, while three are spotted dolphins and two are turtles. A total of 75 humpback whales were observed during these 34 sightings. Although there were only three sightings of spotted dolphins, 50 dolphins were estimated during those sightings.
- In the Observations by Area table, click the Costa Rica record.
The AggregatedGroupBy table updates to display the statistics for the selected Costa Rica area. As you learned previously, this record corresponds to Costa Rica's territorial waters that are not part of any marine reserve. Based on the updated table, 52 humpback whales were observed outside of national parks.
- Click each of the remaining two records to see how many humpback whales were sighted in the other protected areas. Determine the total number of humpback whales observed inside protected areas.
Altogether, 84 humpback whales were observed within protected areas, compared to the 52 observed outside of them. You've answered the second question of your analysis.
- Close the AggregateGroupBy table. Then, close the Observations by Area table.
- Save the map.
In these lessons, you built a bilingual whale survey that tour guides and captains can use to collect marine animal data. Using Survey123 for ArcGIS, you modified an existing survey form to improve the user experience and test the multilingual functionality. Then, you created an app from the survey results and analyzed the observations to answer questions about the spatial distribution of marine animal observations.
By participating in the collection of sightings, the Bahía Ballena community will better understand the humpback whale migration trends between December and April. Researchers can use the survey results to solve critical questions about where the whales migrate and calve and if their numbers increase or decrease as environmental changes occur.
You can find more lessons in the Learn ArcGIS Lesson Gallery.