BIOMONITORING BY MOSSES

Mosses have been used for biomonitoring in a number of different ways, and they are mainly

• 1. indigenous and
• 2. transplants.

Indigenous mosses are naturally growing mosses, and biomonitoring is mainly done by them only. Transplants are “moss bags” and mosses species that are collected from a clean environment, washed with dilute acids before use, and left at a sampling site for a desired period. Within this specific period of exposure to the new place, they show different changes in their morphology and physiology. Transplant mosses are used for local studies, not for accurate studies and high pollution zones. Epigeic mosses grow on the ground and are widely used for the regional surveys in northern and central Europe. Mosses growing on the top of a substrate mainly consisting of organic soil and decaying plant debris are clearly preferable over using epiphytic mosses growing on trees. Many mosses are found on the trunks or branches of trees, and it may be possible that the incoming flux of trace elements from the atmosphere, deposited in the foim of wet or diy forms (Chakrabortty et al. 2006), will be substantially modified by the canopy before reaching the moss, and it is also conceivable that trace elements supplied to the tree from the soil through the root system and eventually leached, for example, from leaf surfaces, will form part of the exposure of the moss. In waimer climates, epigeic mosses cannot be used as biomonitors as they grow directly on the mineral soil and pick up soil particles to a great extent. In such situations, epiphytic species growing on stumps are the best option to detect pollution. Two types of epigeic mosses are used for sampling and survey: feather mosses such as P schreberi and H. splendens and peat mosses such as Sphagnum fuscum. Bryo- phytes are also humidity sensitive, and many species are restricted to specific microhabitats. A very striking feature of bryophytes is that they dry out veiy quickly and at the same time can also absorb minute quantities of available moisture from different sources, like fog, mist, and dew. This environmental water is available in a very small quantity, and naturally, other plants are not able to absorb it, while bryophytes can. However, during droughts, all physiological processes are quickly reduced to a minimum. A few bryophytes grow successfully on calcareous substrates like Tortella lortuosa. Racomilrium lanuginosinn grows on acidic ground, and its presence on the soil surface indicates the acidic nature of soil.

SITUATIONS WHERE BIOINDICATORS/BIOMONITORS ARE USED

• 1. Where the indicated environmental factor cannot be measured, like situations where environmental factors in the past are different than present and palaeo-biomonitoring can be done.
• 2. Where the present factor is difficult to measure the amount of pesticides and their residues or complex toxic that are highly interacting.
• 3. Where the environmental factor is easy to measure but difficult to interpret, e.g., whether the observed changes have ecological significance.

TYPES OF BIOMONITORS

There are different plant and animal species that act differently as biomonitors.

• 7.5.1 CLASSIFICATION ON THE BASIS OF THE AIMS OF BIOINDICATORS
• 1. Compliance indicators: They are used to measure the specific attributes of any population, community, or ecosystem level, for example, fish population in pond. They are used to verify he maintenance or restoration goals.

• 2. Diagnostic indicators: They are used to measure individual or subspecies biomarkars. They are used to investigate the observed environmental disturbances.
• 3. Early-warning indicators: They are very sensitive to a minute change in the environment and are able to give visible response. They can reveal the first signs of disturbance in the environment before any other species get affected.
• 4. Accumulation indicators: They store pollutants without affecting their own metabolism, and at different times, they show different levels of accumulation at different levels of organization, e.g., lichens and mosses.
• 7.5.2 CLASSIFICATION ACCORDING TO THE DIFFERENT APPLICATIONS OF BIOMONITORS/BIOINDICATORS
• 1. Pollution indicators: These species are able to detect the pollutant level in the environment. These bryophytes are sensitive to a few pollutants and show remarkable effect on them.
• 2. Environmental indicators: They are usually species that are able to detect changes in the environmental state. In this case, the organisms are used as early-warning devices, and they delimit the effects of a disturbance, while they may also have the ability to accumulate toxins, which may further be used as a bioassay for the pollutants (Figure 7.1).

FIGURE 7.1 Biomonitor classification.

3. Biodiversity indicators: Biodiversity indicators are environmental or biotic attributes. A biodiversity indicator is a group of genus or tribe whose diversity reflects some measures of the diversity of other taxa in the same habitat. These measures of diversity may include characters like richness, level of endemism, genetic diversity, etc.

4. Ecological indicators: They include species that are sensitive to pollution, habitat fragmentation, or other stresses. These species represent the nature and sensitivity of the community. Due to the effect of pollutants, the species show responses like decline in population size, change in spatial distribution, or any number of life history changes.