Who Live In the Water - Discussion Questions

Discussion Questions

1.  What habitats had the greatest diversity?  What habitats had the lowest diversity?  Why?

More diverse aquatic habitats provide more niches or microhabitats that specialized organisms may inhabit.  Therefore, cobble bottomed streams may have more types of organisms living in them than a silt bottomed backwater.  Keep in mind, however, that many other factors may affect the diversity you observe. The absence or presence of predators can greatly affect diversity and food availability may restrict certain types of organisms. In addition, many aquatic organisms are susceptible to water pollutants or even to increases in water temperature. In these situations, so-called “pollution tolerant” species may be all you will see. Refer to the Missing Macroinvertebrates lesson plan for more specifics on pollution tolerance.
 

2.  How might water pollution affect the diversity you observed?

Typically, in polluted water, many sensitive species will disappear. Often these systems will still have a high abundance of organisms, and may even have higher total abundance of organisms than “pristine” systems, but the number of different types of species is greatly reduced.

3.  How do adaptations of the insects allow them to inhabit different niches in an aquatic ecosystem?

The organisms you collect display an array of adaptations to their unique environment. For example, most organisms you collect in fast moving water either have clawed feet for holding on, have a very streamlined body, or may have some means of attaching to the rocks. Organisms found in soft silt in quiet waters may experience low oxygen conditions. You may find “blood worms,” which are dipteran fly larvae. The red color is from hemoglobin, which helps these organisms trap oxygen when there isn’t much around. 

4.  Would you expect to find similar degrees of diversity and similar adaptations to similar habitats in other parts of the world?

Probably, all else being equal, you might expect the same level of diversity in similar situations. The level of diversity is one ecological measure that scientists use worldwide to compare systems.

5.  Would you expect to find the exact same species (types) of organisms in other parts of the world?

 

The actual species present would probably be very different, and would reflect the evolutionary history of that particular continent or region.

 

6.  What is the best way to express diversity in an ecosystem? 

There are many different diversity indices (a numeric value representing diversity). The simplest diversity index is simply the number of species found at a site. Other more complicated diversity indices weigh the index according to the number of individuals found for each species. For example, a class collects two samples with 10 species each. However, Sample 1 had 91 individuals of one species and only 1 individual of each other species while sample 2 had 10 individuals of each species. Are these equally diverse?