High concentrations of fish and salinity are represented in white, pink, redish brown, and lower concentrations show in orange, yellow, and greens.  

Analysis

By setting the tilapia and salinity distribution maps side by side we should get a sense of any correlation between the two. Each interpolation map contains data of four collection dates. We only chose to show maps of four years of our six years collected so the image wouldn't be too small to view. When viewing the four fish interpolations (the maps to the left) it is easy to see that tilapia population occur mostly on the west side of the Salton Sea, except year 2007 where the data for one reason or another shows a high concentration of fish to the north.

The maps to the right show salinity distribution within the lake. It seems that salintiy within the lake varies greatly. Though we can make some generalizations among the stations. The northern tip of the Salton Sea seems to have stable high concentrations of salinity and so did the mid-western station (shown in white).  

Conclusion

            Besides the Tilapia, the Salton Sea is a significant habitat providing for endangered species such as Brown Pelican, Yuma Clapper Rail and the Desert Pupfish to name a few (Salton Sea Autority). The varying salt content does not seem to bother the tilapia, at least it is not appartly so without further investigation.

Discussion

Upon further study, we would like to extract the data further. Instead of by year, we would like to divide the yearly data into four to visualize the varying salinity within the lake at spring, summer, autumn, and winter seasons. We expect to gain a better idea this way especially because the tributaries within the water basin swell in the spring and summer months do to the rainy seasons and runoffs from nearby agriculture.

Test such as the ones run by the California Department of Fish and Game (where the data we collected was located) is an important source of information regaurding the life of the lake. In 2008, the water level of the lake was deemed to low to dock the boat used in the data collection process and the project was terminated. 

More Recent Fish & Salt Attribute Provides Reports

As we examined the attribute data for the fish, there is a Reports field each contained a link. As we copied and pasted the link to a browser, it lead us to a PDF file of a report by the DFG of fish distribution, with charts, methods, information on net hours, and so much more.

The reports link lead us to many questions we had when we were looking into the data. The question we had about the missing data points after 2004 was answered: the middle three points were not sampled after that year due to redundant data. Therefore, for the following sampling points, 11 points were used instead of 14.

We explored and looked at each PDF file. It provided insight of the health of fish, besides tilapia, as well, for each season. There are charts of the fish data at the end of each report.

Source - PDF File links
Summer 2003: http://www.nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=6341
Summer 2004 : http://www.nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=6347
Summer 2005 : http://www.nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=6348
Summer 2006 : http://www.nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=6349
Summer 2007 : http://www.nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=6350
Summer 2008 (termination of data sampling) :
http://www.nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=6340

Running IDW for Fish & Salt

FISH
Our first attempt at interpolating was with the tilapia fish data.We examined what exactly we are interpolating. We felt that by separating the catch of fish per year it would give us a more narrow result for the sake of interpolating. We were hoping that interpolations would give us a result in which the number of fish per point would project come out to an average. Because we were working with year-round data, the number of fish varied per pull date. We felt that the results, regardless of the wide range of numbers, may still give us a good idea of the fish distribution throughout the lake in correlation to salinity.

SALT
We ran interpolations for each year of salinity, and the results were similarly radical to the interpolations for the fish data. Going back to examine the attribute data, I looked at the different Salinity fields in the 2003 layer. Since we had to create a new Salinity field due to the integer type, our N/A values were converted to 0. putting the fields next to each other, it is evident that the zero values are because of the N/A values. This means that perhaps the reason why each interpolation has a radical and not similar result could be in part of those zeros making the numbers skewed. This definitely helps us narrow down what we are interpolating in terms of salt. When it comes to fish data, the zeros represent no fish.

Our next step is to go back into the five layers we originally exported per year, choose the fields in which the Salinity is above zero, and interpolate them all over again.

Working with fish & salt vector sampling data

Our fish layer provides data on the following fish: tilapia, croaker, crovina, sargo, and other. We decided to use tilapia since it is the most abundant fish found. Also, tilapia is the fish that prefers waters with high salinity content.

As we look into interpolating our fish data according to year, we notice that the first year of net catching, 2003, it comes with 14 points. When we exported 2004, there were 13 points. From 2005 through 2008, it has been reduced to 11 points of data sampling. The same number of data sampling applies to the salt content data. Below is a map of the Salton Sea with symbols representing the points from 2003 and the ones lacking from the following years.

 

Missing data followed in 2005 by not adding data from the middle three points. We predict that there might be some skewed results when we run our interpolations. 

For the fish data, under the Spatial Analyst tool on ArcToolbox, we used the IDW tool for our five exported layers of fish catch data. We used the TILAPIA field for the z-value field. 

We decided to run the interpolation tool for the Salt layer as well, by exporting each layer by year. As we ran the IDW tool, we used a new field we created for the salinity content (Salinity3). We had to create a new field for our salinity layer because the integers under the original Salinity field was a string and not under integer type. 

Salton Sea Map & Data

Done with ArcMap, data courtesy of Dept. of Fish & Game, CA.

On our first map, we have put together on this map initial data we are working with. Above we have pulled up fish and salt data. We have added the bathymetry just for reference, since it is a shallow water body. There are a total of 14 points of data collection. Fish points contain number of caught fish from 2003-2008. Tilapia, corvina, croaker, and sargo fish are found and caught in the Salton Sea. Under the salt points, temperature and salinity will be examined.

We will be using IDW (Inverse Distance Weighted) interpolation in order to see the variation of salt content and fish content between each points We will break it down by exporting date fields per year. Data is collected by season. 

Source:  ftp://ftp.dfg.ca.gov/BDB/GIS/BIOS/Public_Datasets/

Salton Sea 5/13/12

Introduction/Background

Located in Riverside and Imperial counties, the Salton Sea is California’s largest lake. The Salton Sea refers to what is left of Lake Cahuilla, a prehistoric lake that once filled the entire water basin. The Colorado River no longer fills the prehistoric lake, and so it was left stagnate to evaporate. As the water evaporated, salt concentration rose.

            Today the Salton Sea has a salinity of 44 ppt, this is 25% more saline than the Pacific Ocean (Salton Sea Authority). Many species within the lake are dying off. The Tilapia is the main species to live in the high saline water although, they too are now suffering. Rivers that feed into the Salton Sea are also severely polluted, specifically the Alamo and New Rivers to the south. Agricultural runoffs contaminate rivers with pesticides and heavy metals. Our research will strive to address these questions:

·         How will the rising salinity affect fish/birds of the lake?

·         How is the surround agriculture affecting the water quality?

Data

Salton Sea Authority.  The Salton Sea: A Brief Description of Its Current Conditions, and Potential Remediation Projects. 10/3/97. Web. Retrieved 5/10/12. http://www.sci.sdsu.edu/salton/Salton%20Sea%20Description.html

Lawrence A. LeBlanc, James L. Orlando, and Kathryn M. Kuivila. Pesticide Concentrations in Water and in Suspended and Bottom Sediments in the New and Alamo Rivers, Salton Sea Watershed, California. 4/2003. Web. Retrieved 5/13/20012. U.S.http://pubs.usgs.gov/ds/ds104/ds104.pdf

                GIS Data

Fish/ WQ/ Bathymetry layers: ftp://ftp.dfg.ca.gov/BDB/GIS/BIOS/Public_Datasets/

Reference: http://www.spatial.redlands.edu/redlandsinstitute/resources/gis/#data

Methods

Displayed coordinates to Fish and WQ layers. Select by layer to divide dates by year that the data was collected. Exported six years; 2003, 2004, 2005, 2006, 2007, 2008. Used interpolation (IDW) to predict unknown values of fish population and salinity displacement between all six years.  For cleanliness, we masked the interpolation by the Salton Sea boundary.

SALTON SEA - TOO MUCH SALT? OUR 406 FINAL PROJECT

RIP FISHIES

Hi, our name is Marianne & Nick, and we will be examining salinity and the effects it has on species of Salton Sea basin.