I am working on nematodes. For a species serving as bio-indicator, are they highly tolerant or sensitive or both? In my case I got senstive and tolerant species but they are not widespread. Still I can call it a bio-indicator or not. Please suggest.
An indicator is any species that respond to a particular stressor. A sensitive species is one that occur when the stressor is absent; while a tolerant species is one that would occur even when the impact of the stressor is high. Tolerant species may still occur in environment in the absence of stressor.
Whether to select the indicator based on their high tolerance or sensitivity, depends on the objective (why), the stressor (what), and the logistics (when, how).
For instance, if the objective is for management planning, selecting a common species with relatively high tolerance or sensitivity to the stressor may be of more value as compared to a rare species, which would limit the applicability of managing various areas.
Defining the the stressor is the utmost importance, as a species could be both tolerant to one stressor and sensitive to another. An indicator of nutrients for a system may not necessarily respond to heavy metal stress.
Hello,
I think than elaborating a bit on Mohammad's question from a more general perspective may help him decide about his nematodes. If I succeed, this answer will be a useful supplement for Adam's answer.
"Indicator" is of course a methodological term that is roughly defined as an observable variable assumed to point or estimate (indicate) some other unobservable --or relatively difficult to observe-- variable. Thus, should you (justifibly) deem it necessary or convenient, you could make any variable linked with some other variable an indicator, as long as it complies with the characterization above (and a few more requisites you can look at in any good book on the philosophy of science). The quality of an indicator is tightly related to the characteristics of the "link" (connection) between the variables. Strong indicators are directly and causally connected to the variables they point, while weak indicators correlate with the variables to which they point, but the mechanism connecting both variables is missing. The important thing is that you have a good justification underlying your use of an indicator for any one variable of interest.
Cheers,
Any correctly interpreted piece of biological knowledge may have a bioindicative value. The sensitive species are the bests bioindicators. But their autecology and its variability must be well known to avoid misinterpretations. many species change theri ecological requirements within their distribution area. Mechanic overtaking of results from a place to other can be mislading. The simple correlations with some environmental gradients can be even mistaken. Some "sophistised" statistical methods can be even dangerous. Allway a strict logical control and exoerience must be superior.
Bioindicators may be either sensitive or tolerant category. But the sensitive bioindicator show the presence of toxicants or contaminants in water soil ecosystem beyond certain level above the normal range of values. It gives us clue about the adverse change earlier than the tolerant class. The tolerants can tolerate certain level of contaminants and toxicants above the normal range. If they may be little, medium or very highly tolerant. As soon as we can detect the adverse condition it's better for adopting steps toward recovery or reclamation of the ecosystem. Study of the sequential appearance of appearance of those graded species indicates gradual deterioration of water or soil quality. Another point to note that if tolerant species are dominant it means that the status is poor or polluted too much!
- Badges
- Science method
- Similar topics
- Biological Science
- Ecology