Conservation of biodiversity Use of biotic indices and indicator species in monitoring environmental change

What are biotic indices? Biotic indices are numerical values based on the presence of indicator species which are species sensitive to different environmental conditions Biotic indices use pollution tolerances of endemic organisms and are regionally specific.

Human activities and the effect on major biomes The effect of human activities is not always known Important to have early detection of environmental change Environmental impact assessment (EIA) It is important to have baseline data when measuring the environmental impact of a human activity

Biotic indices and indicator species of environmental change Some organisms are particularly sensitive to change in their environment Numbers and the condition of these species in threatened habitats can be monitored. Their health can therefore function as biological indicators, or biotic indices, of impending environmental change.

Direct and indirect methods of measuring environmental status, e.g. water quality

Direct methods These record the abiotic aspects of the environment Such as turbidity, flow, temperature, pH, light intensity etc And include chemical tests to measure disovled oxygen, salinity, turbidity, nitrates, phosphates etc. But, these methods can only give an indication of the water quality at one point in time

Indirect methods The biotic part of the ecosystems Biodiversity within an ecosystem e.g the Simpsons Index BOD (Biological oxygen demand) The biotic index, using the presence of species sensitive to different environmental pressures within the ecosystem, i.e. indicator species These values give a better understanding of the effects of environmental changes as they show health of the whole community over extended time periods

Types of indicator species Macroinvertebrates, for detecting changes in aquatic ecosystems Lichens for early detection of atmospheric pollution (SO 2 ) Large trees, for long term changes in terrestrial biomes and ecosystems

Macroinvertebrate indicator species Easy to see and identify e.g. mayflies, caddisflies, true flies, snails (see keys) Have a life cycle of at least a year Relatively sedentary, confined to the area being sampled They have a range of responses to different pressures. Individual species have specific tolerance ranges and habitat requirements

Macroinvertebrate biotic indices Individual species, genera or families in a sample are scored according to their sensitivity or tolerance to the pressure

Aquatic Invertebrate Data Recording Sheet

Using the biotic index These scores are then combined to produce a single value which can be used to interpret the current state of the environment. Examples of biotic indices Trent Biotic Index, the Chandler Score and the Biological Monitoring Working Party (BMWP) score

Examples of aquatic indicator species Pollution Tolerance Indices For Aquatic Invertebrates

The damselfly larva Calopteryx splendens

The presence of this larva indicates clean water Slow flowing water and a silted river bed. It is also intolerant of acidification and increased salinity Species like C. Splendens are used to formulate biotic indices based on acidification, flow velocity and siltation

Pollution Tolerant Species: Presence of these species indicate water of low quality, however they may be present in all types of water. blackfly larvae Flatworms Leeches Roundworms Blood worms/midge larvae

Moderately Tolerant Species: Presence of these species in great numbers may be a sign of fair water quality. caddisfly larvae dragonfly nymphs damselfly nymphs

Pollution Intolerant species Presence of these species in great numbers may indicate good water quality. mayfly nymphs stonefly nymphs

Aquatic Invertebrate Data Recording Sheet

Example of Biotic Index Calculation Using Macroinvertebrate Information You may find in an aquatic ecosystem: 25 Mayfly larvae 15 Caddisfly larvae 20 Stonefly larvae 20 leeches 20 Midge larvae

Multiply each by the Biotic Value: BIOTIC VALUE No of organisms X biotic value Biotic value 25 Mayflies Caddisflies Stoneflies leeches Midge larva4.0 Total number of organisms =TOTAL biotic value =

Divide total biotic value by the total number of organisms to get the biotic index value The biotic index value is ……………. Use chart to determine water quality based on Biotic Index Value Based on the Biotic Index Value, the water quality is ……………………………. Water Quality Biotic Index Very poor> 9.0 poor Fair good< 6.0

Worked example: BIOTIC VALUE 25 Mayflies5.525 x Caddisflies5.515 x Stoneflies1.520 x leeches8.020 x Midge larva4.020 x 480 Total number of organisms = 100 TOTAL biotic value = 490

Divide total biotic value by the total number of organisms to get the biotic index value 490/100 = 4.9 Use chart to determine water quality based on Biotic Index Value Based on the Biotic Index Value, the water quality is good. Water Quality Biotic Index Very poor> 9.0 poor Fair good< 6.0

Lichens Indicator species of air pollution

Lichens: mutualistic organisms

Lichens are mutualistic organisms. Their bodies consist of a leaf like thallus made of the fungal part and algae (or cyanobacteria, photosynthetic bacteria) Several thousand different species of lichens The fungal part absorbs and retains water and ions the algal part carries out photosynthesis

Lichens are highly susceptible to air borne pollutants They have no waxy cuticle and the lichen thallus absorbs and accumulates pollutant Lichens rapidly accumulate sulphur when exposed sulphur dioxide pollution The algal part is most affected by the sulphur dioxide; chlorophyll is destroyed and photosynthesis is inhibited. Some species are more vulnerable than others bushy lichens need really clean air leafy lichens can survive a small amount of air pollution crusty lichens can survive in more polluted air

Lichens as indicators of SO 2 levels Since industrialisation, many lichen species have become extinct in Britain For example the beard moss Usnea articulata.

Trees as indicator species

The sweet chestnut tree grows on acidic soils not on soil rich in lime. This species is an indicator of soil conditions

Other indicator species

River otters have been used as indicators of healthy, clean river systems.

The spotted owl is an indicator of old growth habitat.

Coral bleaching is an indication of rising ocean temperatures.

The Northern Cricket Frog is an indicator species for water quality.