Some types of monitoring focus on the water itself, and its physical, chemical, and biological characteristics. This type of monitoring may look at the temperature of water over time, changes in its rate of flow or total volume in an area such as a lake or pond, or the pH (acidity/alkalinity) of the water. The monitoring may be done in order to assess the safety of the water for use by humans for drinking; is water from this stream low enough in harmful microorganisms to be directly usable without treatment, or does it require biological filtration? Monitoring may be done to ensure that water used in irrigation stays below a certain level of salinity and does not contain any of a number of pollutants. Monitoring could also be done in order to make sure that a pollution-control system upstream is working as intended.
Other types of monitoring are focused more on the species living in the aquatic environment. Marine biologists often engage in population surveys in a particular region, measuring the prevalence and population of a specific species or group of species. One famous example of this type of research is the tracking of salmonid numbers in the 20th century, which led to the discovery that increasing acidification of streams and oceans was impacting salmon and trout populations. This type of monitoring is done in several different ways; for large species such as oceangoing mammals, scientists may actually attach tracking devices to specific members of the species and gather data from the individuals’ movements, while for smaller creatures like fish, techniques such as gill-netting an area and then counting the fish in the net may be employed. Less invasively, water sampling might be done to measure bacterial levels when that is the focus of the research goal.
The specific environment being studied is of course highly relevant to how that environment can be monitored. Environmental monitoring of an aquatic environment can be done at a very “micro” level – a single sensor taking readings from a small aquatic habitat like a fish tank is technically monitoring that aquatic environment. At the opposite extreme, satellites in space can monitor vast expanses of ocean, at least coarsely. Most commonly, the scope of the aquatic environment to be monitored will dictate the range of appropriate monitoring solutions, whether that be simple cameras or sophisticated orbital satellites.
In next week’s blog we will take a look at the various ways in which monitoring of the aquatic environment is actually carried out.