With the data we will be collecting from our sensors, it is important to model short-term, medium-term, and long-term trends in order to determine the health of the Galapagos ecosystem. A baseline will have to be determined experimentally once the sensors are in place; however, at this time there is some information about what is healthy and unhealthy in certain ecosystems similar to those on the Galapagos Islands. In this appendix some of this data will be listed. This is only a partial list: the sensors would fill in the blanks to give us a complete picture and a set baseline.
Ocean temperatures: Sea surface temperatures in the Galapagos range from 18-23 degrees Celsius depending upon where in the Galapagos the temperature is being measured. El Nino events cause a rise in these temperatures. For example, during the 1997 El Nino the sea surface temperature was 28 degrees Celsius for a prolonged period of time, wreaking havoc on the marine ecosystem. Sensors monitoring sea temperatures are part of the design. In a short term sense, it was felt that a sharp sudden spike or drop of 5 degrees Celsius over a very short period would be cause for great concern. In a medium term sense, a rise or drop of a few degrees Celsius that persist for weeks or months would be cause for concern. In a long term sense, seeing that there is a trend over years that shows that the ocean temperature is rising or dropping would be cause for concern.
Salinity: Mangroves are an important ecosystem in the Galapagos. They are extremely sensitive to salinity (and pH, see below). 30-36ppt salinity is a normal average for ocean water: anything outside of this range for an extended period of time should be watched closely.
pH: Mangroves are also sensitive to pH changes. They can live in a pH range of 5.3-7.8. A very dramatic spike over a short period of time or a smaller change that lasts for a long time would be cause for concern.
Moisture in the arid zone: The Galapagos Islands have several arid zones where cacti that require a very dry environment grow. Rainfall on the Galapagos is generally measured not in centimeters but in saying that rain fell on a certain number of days in a year. On average measurable rain falls 50 times a year.
During the last El Nino (which was extremely severe) rain fell over 200 times that year, and the cacti roots were rotting. These cacti feed endangered tortoises, so it is important that they remain healthy. After approximately100 measurable rainfalls a year there should be cause for concern about the cacti.