Chlorophyll a concentrations, phytoplankton cell number or biomass and ecological indices or species diversity of phytoplankton, zooplankton and polychaetes are among the bio-indicator often employed to assess pollution levels. Ecological indices seem to be nowadays-standard practice in water quality assessment as well as in monitoring environmental changes. Biological indicators help to make the assessment simple, when comparing with assess various physical parameters for concluding the pollution level or eutrophication of the water body.

Those organisms which have these features: living in sessile style, high abundance, easy to culture in the lab and easy sampling, tolerating high amount of pollutants without death and occupying an important position in the food chain.

Thank you guys for your thoughts.  

when it is hard to determine a group of optimized indicator. A systematical group of indicators by using dominant species and their sensitive pollutant tolerance, as our work in "WST: water supply" suggests, maybe a practical way.

Several factors are involved in selecting appropriate biological indicators. It depends on the type of ecosystem (stream, wetland, lake) and properties of your water body (fresh water, brackish or marine water) you are dealing with, geographical areas and etc. I would suggest you to consult the following book. There you may get a very good idea of selecting proper indicator species or groups and index applicable in your region. 

Ecological Indicators for Assessment of Ecosystem Health,Second Edition by, 

Sven E. Jørgensen, Fu-Liu Xu, and Robert Costanza, 2010

CRC Press, Taylor & Francis Group

Thank you Javid Imanpour Namin for your suggestion

Acanthocephalans. Much literature

Thank you Prof. Omar Amin. Are they marine or freshwater Acanthocephalans, just interested.

Depends on the environment. Cladoceran Daphnia magna and unicellular algae Selenastrum capricornutum might be good test organisms for freshwater ecosystems. You can easily find a few papers about it. Sensors might indicate the presence and concentration of toxicants, but give no answer about the biological response.

Hi, you can refer the book "Bioincators and biomonitors: principles, concepts and application" edited by Makert B.A., Breure A.M and Zechmeister, 2003. I think that you can find alot of information you are interested. Hopefully it will be helpful to you.

Ummer. Which indicator spp you use depends on many thing from what you question is to which pollutant you want to track and which environment the pollutant is in. We used fish eagles to track aquatic pollution because they are fish eaters (mostly). Also, the age of the individual sample and past/potential migratory history should be considered. This is why we used hatchlings, we knew they had not migrated all their food was coming from near by and birds that can't fly are way easier to catch. 

Any highly sensitive species or highly non sensitive species to the toxicants may be use as bio indicator species. However, Bioindicator species must have fulfil the following characteristics features :

1. Easy to rare under lab. condition.

2. Short life span

3. Repeated generation

I would like to send you one my published article, follow the link

Article 1. Shaukat Ali, Farida Begum, Syed Arif Hussain, Ahmed Saeed...

Thank you Showkat Ali for sending your nice paper.. Cheers!

All previous answer of RG member mentioned the criteria of. Biological inductors. It's important to know you treat with an environment which is complex to use only one issue for evaluating their status. I had put in Q&S the following Q:

Which is more reliable for assessment of water quality: physicochemical parameters or biological indicators.

You can find the following article on my page in RG:

The Study of Pollution of PAHs (Polycyclic Aromatic Hydrocarbons) in Al-Hilla River, Iraq by Using Bioindicator Freshwater Crab (Sesarma boulengeri Calman).

Hi Ummer,

Another issue which needs to be considered in many monitoring programs is the resources needed to use an indicator. While some can be fantastic at measuring responses to pollution or directly measure the pollution itself they are either time consuming, or expensive to analyse. Very few programs have an unlimited budget, unlimited staff or staff skills to cover everything needed. So selection of indicators is crucial to get an outcome you need. Otherwise, the previous comments summarise most of the issues. Including:

• a known response to the pollution
• tested in the the location where being used - many known indicators with a response in one place can be mediated by the interactions with other ecosystem attributes at another place
• life history traits need to be known but not necessarily have to be short or long depending on the attribute being measured - their are also non-destructive and destructive bioassay techniques 
• low variability in response - although high variability can also be an indicator in some cases

There are many issues to consider if selecting a pollution indicator and there are many papers out there that list the criteria you can consider. We use the SMART method

Simple, Measurable, Achievable, Relevant andTimely.

See: Alexandra J., J. Higgins & T. White (1998) Environmental indicators for national state of the environment reporting – Local and Community Uses, Australia: State of the Environment (Environmental Indicator Reports), Department of the Environment, Canberra.

Cheers

Pete

As to which biological indicator to use, you will be guided by pollutant type, mode of action of the pollutant, its life time, availability and the variables in question i.e growth, skin color change, height, death, accumulation LD50 doses etc. As to why use them when we have several chemo-sensors, I think it is important to note that although a particular pollutant might be in an ecosystem, speciation and bio-availability are dictated by different environmental conditions such as temp, pH, sulfur and iron content, turbidity, presence of algae etc. And in most cases, the toxicity of the pollutant to aquatic life will solemnly depend on which particular pollutant species is available (Hg mercury is an example). This chemical speciation is not constant at any one point as environmental conditions will greatly differ from time to time. Therefore, in order to get the exact environmental impact of a pollutant, biological monitoring is more prefered although for human extension, giving both physicochemical measurements and biological measurements is a requirement that one should endevour to give. 

You'll find very helpful information about monitoring and biological indicators on the EPA CADDIS site:  http://www.epa.gov/caddis/

Try sampling of stoneflies (plecoptera) or Hydrachennalle (water mites) as they are the best bioindicators for fluvial especially rhithronic and  hyporheic substratum . There are several others based on the macro/ microhabitat.

Environmental quality assessment vis a vis pollution assessment is a dynamic process. on choosing a particular indicator species for a  particular study there are specifications and principles which I think learned colleagues have really emphasized above. In assessment like though there are ideal standards but the stand bio indicators relates to bio related pollution. e.g in micro biology indicator species of organisms otherwise known as coliform group of organisms have been the organisms used in feacal contamination test on their ability to ferment lactose  broth within some specifiedconditions etc. e.g E. Coli, shigella, enterobacter. etc. so for feacal / sewage contamination coliform group of organisms are ideal this kind. Thanks

I suggest to read the following valuable book::

Bioindicators & Biomonitors

Principles, Concepts and Applications

2003, Edited by: B.A. Markert; Zittau, Germany; A.M. Breure; and H.G. Zechmeister

I think there are a few criteria to consider for any indicator species.

1. sensitivity to whatever you want to assess (ie a known response that is relatively quick)

2. low variability in response (ie response is the same/similar for all individuals)

3. a relatively common species (ie no use using a rare species which isn't going to be naturally in an area you want to assess)

4. ease of sampling

5. costs of sampling

In terms of why use a biological indicator rather than a physical or chemical measure?

I think this will be determined by the objectives of your assessment. Usually it is biological because there aim is to assess an impact of pollution on the ecology of a system. This is especially important where areas have an ecosystem that is not sensitive to types of environmental change or pollution. eg. some riverine ecosystems will not respond to increased suspended sediment during an event because they are naturally turbid and the biota have evolved to cope with spates of increased turbidity.

Ideally therefore use of both biological and physical/chemistry measures will provide multiple lines of evidence as to any pollution occurences and impacts.

The simplest method, faster and low cost organisms should be considered for smart results where equipments are lacking.

Hi Ummer!

A lot of the answers have already summarized what criteria you should look at, so I'll recommend a particular group of organisms that can be used as bioindicators of pollution. Our current research focuses on testing the toxicity of riverbed sediments, particularly their inorganic pollutants, through a bioluminescence toxicity assay. We are planning to use the bioluminescent bacteria Vibrio fischeri.  The bioluminescence of bacteria is extremely sensitive to exposure to toxic chemicals, and it responds very rapidly. The methodologies available for measuring bioluminescence reduction are also relatively simpler and cheaper than say, animal-based methods. You can use a lot of different systems with set methodologies such as Microtox and LUMIStox assay. There are also different kinds of bioluminescent bacteria that can be used (V. fischeri, V. harveyi, Phosporeum bacterium) which may be readily available depending on your location. At the end of the assay you will be able to determine the concentration of your substance that reduces the bioluminescence to a certain degree (20% or 50%) and you can relate this to its extent of pollution.

Biological indicators are necessary for pollution assessment because they allow the observance of the direct effect of pollutants on actual organisms. Simply quantifying or detecting the concentration of pollutants isn't enough, since not all pollutants are biologically available to cells.

Hope this helped!

Sam

True observation of effect on pollutant on organisms/ cells through Histological studies are sensitive  indicators as far as such new equipments are not available or financially unsustainable in Africa and less developed countries. Development deficiency you say. We are still coming behind

According to what do you to monitor?

some organisms are sensitive to some pollutants and other not.

also according to the media organisms for seawater are different than fresh water.

in most cases and most studies they used bacteria for the toxicity or as indicators

to measure the bioluminsence of bacteria and the  famous one if Vibro bactrium. also there are studies for artemia for sea water but this for mortality only.

regards