Biological indicators are more reliable assessment for long term ecological changes in the quality of aquatic system compared to its rapidly changing physico-chemical characteristics

I believe biological indicators are more reliable in long term effect monitoring and their observed changes are as a result of changes in the physico-chemical so ideally it depends on the nature and scope of the study.

For studying ground water analysis physicochemcial parameter are important.

For studies related to rivers, pond etc biological indicators are important.

The choice is more of purpose based, it depends on the purpose of the assessment. For example, if the assessment is to check whether the water is potable or not, both parameters are to be checked. If you are looking to assess the water quality in terms of its ecological functionality biological indicators can give a better picture. And, if you're looking for the industrial usage of the water, physio-chemical properties are of more significance.

Biological indicators can help you infer the physio-chemical properties of water but it will not give the exact picture of different and very important (depending upon the usage) physio-chemical properties.

To assess water quality, both the physicochemical parameters or biological indicators are important. As general and base water quality assessment, the physicochemical parameters is enough. While the detail assessment of water quality need to be conduct, both physicochemical parameters or biological indicators have to analyze.

It depends from the scope of assessment.

Water Risks may be classified, based on their temporal effects, in short and long term. To classify water normally you make laboratory analysis.

The biological indicators, a posteriori, normally provide informations about long term effects. The power of biological indicators is that shows impredicable interactions or side effects: a massive fish death or a general unhealthy state may happen with all physicochemical normally monitored parameter ok.(ex BOD5, COD, PH, T°, Nitrogen, Etc. )

It is not possible sample all.

The biological indicators can be seen as an electric capacitor that is charged (often slowly), until reaching a detectable voltage at the terminals.

The chemical analysis provide informations about short and long term effects.

Example:

A value of BOD5 = 8000 mg/L (Biological Oxygen Demand, a biological parameter), implies effects in a short time term. Also the biological indicators in this case show immediately the problem.(After death of fishes normally physicochemical parameters are monitored. Fishes are a pilot light).

If you remove the cause of the problem, normally mother nature repair itself in short-medium time term.

A value of Arsenic (chemical parameter) = 10 microg/L, implies effects in a short and medium time period and in a long time term, because it may accumulate.

Also the biological indicators evidence the problem, but they need time to show the problem of bioaccumulation.

If this case if you remove the cause of the problem, the environment may repair or not repair itself in a very long time period.

Dear Giorgio Demontis,

Thank you for your valuable answer, hank you for your valuable answer. The measurement of physicochemical and also pollutants needs chemicals and some apparatus that may be expensive, while the observation of dominant or exist some of biological indicators give as indicator of environmental alteration and may less expensive.

Regards

Biological indicators my be provide big picture about the environmental change in nature  

there are three areas to be considered in water analysis, the physical, chemical and the biological analysis. The outcome of these analysis will depend on what the water could be used for. As contributed, the scope of the work will determine to what extent the analysis can be done.

Dear Fikrat

I totally agree with you.

The biological indicators are certainly less expensive and allow you to extract more information in case of problems not instantaneous. When used properly can predict the future.

The limit is that they are not very effective with respect to chemical analysis for the water that will be drunk between six hours.

Here's an example in another field.

From the chimney of a small incinerator fumes are released into the atmosphere. The fumes contain heavy metals and other.

The pollutants fall mainly on the surrounding areas and then enter the soil and water, and then the biological cycle.

There are two ways to monitor pollution.

a) Analysis on chemical fumes when they come out of the chimney, at programmed time intervals. This method looks like a message in a bottle. I know what's inside, I do not know who will read it.

b)  Health status of biological organisms that live in the area, together with the analysis on them.

a) is a priori method. Check in advance everything that is harmful is impossible and too expensive. In this case a), has a positive effect primarily for those who do the analysis, in case it evaluates only the exceeding of thresholds.

b) is a posteriori method. Is effective in the medium and long term if I check the health of organisms over time. Biological organisms with low mass and short cycle of reproduction show early enough the possible damage that will occur on bodies with masses more high.

By monitoring the evolution of the damage on the environment by using biological organisms present, I have the opportunity to take corrective actions early.

Currently a) is the method prescribed in Europe. It is expected that dioxins in milk exceed the limit value for declaring the problem.

Dear colleague, this question is related with the origin of the water sample (reservoir?  temporary or permanent stream? river? well?) and also with the parameters needed to be measured depending on the objectives (drinking water? ecological survey? irrigation? ecotoxicologial tests?). In general, physical-chemical as well as biological parameters is always needed, but depending on the previous questions the number and kind of analysis could change  

Physico-chemical parameters can reflect the situational quality of water which changes time to time due to change in energy status. Biological parameters can depict the condition of water for a long time; Hence the latter is most essential in this study of water quality monitoring strategy.

I think there is an integration between them and both are important as indicator

I think that it is the water quality creteria based on biological information. The new revised system which is suported by OECD and EAP is given in Table 14 of this pdf.

At possible pollutant entry points, it is important to check the physico-chemical parameters in order to extrapolate pollution risk assessment. In aquatic systems, physico-chemical parameters will give present aquatic life health status. However, this is never enough as bioconcentration/accumulation will give a better understanding of the long term aquatic system health status. For instance, some chemicals can easily be reported at below detection limit and their fate can only be understood using biological samples. As such, I would give biological indicators preference over physico-chemical parameters when it comes to accessing aquatic systems.  

We used two/three ways of WQ monitoring to assess river water quality for example for pollutants such as trace metals monitoring  (1) using innovative passive sampling technology (for spatial and temporal distribution of metals and identifying pollution hot spots),  and (2) use of biota and in some cases (3) spot water sampling

Reference

https://www.researchgate.net/publication/261178237_A_Training_Manual_for_Deployment_Retrieval_and_Handling_of_Innovative_Artificial_Mussel_Passive_Samplers_for_Trace_Metals_Monitoring_in_Rivers_Creeks_and_Channels-_Australian_Model

Patent A Training Manual for Deployment, Retrieval and Handling of ...

Hi Dear All, It depends on your objective. If you are going to know the water quality for drinking purpose than both physico-chemical and biological parameters are important but for crop production and irrigation physico chemical parameters are important. Thanks

For human and animal consumption, biological as well as physic-chemical parameters are all important. For crops and plants, only physico-chemical or may be only chemical parameters are enough. However, with experience you may judge water quality with very few basic parameters like EC, pH etc.

dear fikrat

Currently, I'm doing the same research that you of water quality. then I suggest you more of what has been said by my colleagues, to microscopic observation of the water. it allows even the presence of foreign elements such as poluants, microorganisms, polènes .....

I think the best solution is to do both ways. More indicators involved, more reliable are the results. Sometimes chemical parameters are not showing you what is really going on because they can be in the allowed limit and in meantime water biota is suffering the effects of bioacumulation of different chemicals found in water column or in sediments. The last one are of great importance.

All of the responses are right in all senses. However, for short term and emergency of epidermic issues, the biological aspects will surface but on long term basis, the physicochemical assessment will be the answer, supported by periodic biological consideration.

A complete analysis of physicochemical and biological parameters give reliable assessment for water quality.

I agree with Yilkur Lohdip and Selvaraju Sivamani 

Historically water quality monitoring programs have focused on water chemistry criteria. But today they are more likely to focus not only water chemistry but also biological and hydrological characteristics. Indeed, the use of biological communities as indicators of water quality is evolving our understanding of the interactions between water quality and the integrity of biological community. Today, ecologists and water managers believe the water in rivers can be classified based on biology, hydrology and water chemistry into different ecological categories of condition such as  bad, poor, moderate, good or excellent.

I would say that a combination of physical, chemical and biological parameters is the modt appropriate in a water quality assessment.

A complete analyses of physicochemical and biological parameters give reliable assessment for water quality. If you have choice for one then go for physicochemical parameters bcz the phsicochemical parameters determine the biological parameters.

I think the best solution is to do both ways. More indicators involved, more reliable are the results. Sometimes chemical parameters are not showing you what is really going on because they can be in the allowed limit and in meantime water biota is suffering the effects of bioacumulation of different chemicals found in water column or in sediments. The last one are of great importance.

Hi Fikrat Hassan; I agree to your opinion, of course physico chemical tests require chemical and hence they are costly. But for drinking quality purpose I am still of the opinion no compromise should be done with health. Thanks

Since the question is asking about a choice that may have to be made between physico-chemical tests and biological tests, for whatever reason, my quick answer is physico-chemical tests are more important. Why? The biological nature of water is dictated upon by the prevailing pysico-chemical properties of water. For example, if a water body is nutrient-rich, algal blooms can be expected, and some fish such as trout may disappear in such eutrophic systems. So while both tests corroborate with each other (thus doing both tests can be more revealing), physico-chemical tests are more important (if a choice has to be made) because they dictate what type of biota can prevail in a water system and to what extent. In addition, you can gain far more insights into an aquatic ecosystem with pysico-chemical tests than can be manifest with biological tests most of which are based on nothing more than mere presence/absence of index species.

Estimation of physico-chemical parameters gives a direct account of their concentration whereas estimation of biological parameters gives an indirect concentration of many parameters through the effect. Choice of the methodology also depends on the geographical area - while for urban areas and the like, it is better to go for biological parameters whereas in other areas, it is better to go for physico-chemical parameters.

All parameters (physical,chemical and biological ) were important in assessment of water quality to provide complete picture about ecosystem health  and interaction between this  parameters .     

dear Jasim,

may be some time biological inductors give us more reliable to assessment WQ

I think, we have to use simple and fast way to assess the  WQ

I think In order to get clear picture of water quality over a longer period of time, we need to look at the biological community

Dear Abdul Hameed,

Yes, i think so.

Biological indicators can portray the changes in water bodies. Biological communities exposed to pollutants integrates both past and present environmental phenomena. This characteristic trait makes us consider biological communities as a convenient index for water quality assessment.

It's depends on the purpose  and  the outcome the study. Physio chemical parameters will assess the  pollutants nature prevailing over a short period of time interval  and biological indicators will reflects an average pollutants for long range order(time period). 

Depends on the objective of the research work, physicochemical parameters or biological indicators wll assess the

According to your desired goals, you need to specify your parameters. If you are going for the suitability determination for drinking water purpose, you have to measure both physico-chemical as well as the biological indicators. And if you only want to know the pollution status, sometimes biological parameters are enough.   

If you are interested to do a deep research of pollution effects on water biota, it would be worth to do both physiochemical and biological parameters.  In this case you will have a very good picture of what had happened in the ecosysytem. Biological parameters give a reliable history of the past and present status of water body.

Dear All,

Thank you for your contributions.

Regard

thanks for updates!!

I think  the use of bio-indicators more reliable assessment and not expensive.

 So sorry , i am so late in response. But , let me have my own say . i feel , biological properties are more important than physicochemical properties , since they relate directly with the health and hygiene ..besides physicochemical properties eventually have the cascading effects on biological properties of water quality...

Dear Anoop,

I think so, but its important to ,measure the physio-chemical parameters.

biological indicators i think.are more important as far as i think