Ecology is the study of the complex system of interrelationships existing among living organisms and their abiotic (physical and chemical) and biotic (living) environments and themselves. The abiotic factors in the environment determine the ability of organisms to live and reproduce. We will measure the physical parameters of our waterway, which determine the types of organisms that can live there.
The physical parameters also have strong effects on the chemical and biological measurements. Factors such as flow velocity, volume of water, bottom contour, currents, depth, light penetration, and temperature govern the ability of a system to receive and assimilate pollution. To evaluate these data, you need to know the physical status of your waterway in terms of temperature, weather, stream flow, etc. You also should know whether physical conditions are similar to compare data from different field trips.
The following parameters are just a few that can be measured:
The chemical and physical sampling and analyses provide a broad picture of the parameters that define the aquatic environment. Now we will examine the living components of the system. Biological investigation of an aquatic community can determine the extent it has been affected by human activity.
Biological parameters detect water quality problems that other methods may miss or underestimate. Organisms in their environments are continual monitors of environmental quality, increasing the detection of events such as spills, dumping, treatment plant malfunctions, nutrient enrichment, non-point source pollution (such as agricultural pesticides), cumulative pollution (multiple events over time or continuous low level inputs) or other impacts that chemical sampling is unlikely to detect. Impacts on the physical habitat such as sedimentation from storm water runoff and the effects of physical or structural habitat changes such as dredging, filling, or channelization can also be detected.
"Resident biota are continual monitors of environmental quality, increasing the detection of episodic events (spills, dumping, treatment plant malfunctions, nutrient enrichment), nonpoint source pollution (agricultural pesticides), cumulative pollution (multiple impacts over time or continuous low-level stress) or other impacts that chemical sampling is unlikely to detect. Impacts on the physical habitat such as sedimentation from storm water runoff and the effects of physical or structural habitat changes (dredging, filling, channelization) can also be detected." (EPA 1994).
Plankton (phytoplankton and zooplankton), benthic macroinvertebrates, aquatic plants, and fish are the most commonly used in assessing biological integrity. The selection you make will depend on the type of waterway you study. For example, benthic macroinvertebrates are most often studied for wadeable riffles in streams and rivers. Algae are often used in lakes to examine eutrophication.