Bio-indicators and biomonitoring

Marinda AvenantCentre for Environmental Management

University of the Free State

31 January 2012

MOB743: Measuring biodiversityMOB743: Measuring biodiversity

Biological monitoring

The systematic use of biological responses (or ecological indicators) to measure and evaluate anthropogenic changes to the environment with the purpose of using this information in quality control programs.

The core principle of biomonitoring is to detect divergence from biological integrity (especially divergence attributable to human actions). (Karr, 1999).

Where has it all started? Measuring biological integrity

1900s Quantitative indices

Indicator sp.; guilds; sp. Richness; sp. Diversity; similarity indices etc.

Clean Water Act of 1972

Index of Biotic Integrity IBI (Karr et al., 1986) Multi-metric index Integrative ecological index that

directly relates fish communities to other biotic and abiotic components of the ecosystem.

Where has it all started? 1972 Clean Water Act (USA) mandated:

“Protection of River health… restoring and maintaining the chemical, physical and biological integrity of the Nation’s waters”.

Where has it all started? Measuring biological integrity

1900s Quantitative indices

Indicator sp.; guilds; sp. Richness; sp. Diversity; similarity indices etc.

Clean Water Act of 1972

Index of Biotic Integrity IBI (Karr et al., 1986) Multi-metric index Integrative ecological index that

directly relates fish communities to other biotic and abiotic components of the ecosystem.

Integration of land use impacts on drivers, habitats & biological responses

Louw & Kleynhans, 2007

Where has it all started? In South African context

SASS – Chutter (1972) 1990s FAII (Kleynhans, 1999) FAII takes into account:

Relative intolerances of fish species

Frequency of occurrence General health & well-

being

FRAI; MIRAI; VEGRAI

Biomonitoring of water resources required by Law

National Water Act (1998) Chapter 14 recognizes

monitoring of water resource quality as an integral part of water resources management

National Water Resources Strategy (NWRS) Need different monitoring

systems to give a comprehensive expression of the state of the environment

Concepts of “River health” and “Ecological integrity”

“River Health” concept

River health can be defined as the degree to which the three main physical & chemical attributes of a river (its energy source, water quality and flow regime), plus its biota and their habitats, match the natural conditions at all scales. (Karr, 1991)

What is Ecological Integrity?

The capability of an ecosystem to support and maintain a resilient community of organisms having a species composition, diversity, and functional organisation comparable to that of natural habitats in the region. ( Adapted from Karr & Dudley, 1981).

Ecological integrity = habitat integrity + biological integrity + physical-chemical integrity

Ecological integrity = habitat integrity + biological integrity + physical-chemical integrity

Ecological integrity

Nothing alive

Severe disturbance

Gradient of biological condition

Gradient of human disturbance

Pristine

No disturbance

Unhealthy

Not sustainable

Healthy

Sustainable

Biological integrity

Threshold(After Karr & Chu, 1999)

LOW ecological integrity HIGH ecological integrity

Can we determine ecological integrity?

Biotic integrity can also be viewed as a measure of the degree to which the present biological condition of a system has been modified relative to its natural state.

Natural state (Reference conditions)

Natural state or reference condition

Condition with no or minimal anthropogenic stress.

In the absence of ecosystems in their “natural state” the concept of “best attainable” is relevant.

Reference state = benchmark

How do we determine reference conditions?

Locate the least impacted sites, either in the same river zone or in a river that is ecologically similar.

Use results of historical surveys before human impacts, or from ecological similar rivers. Use historical photographs and land cover data.

Expert knowledge. “Ecoregions” “Virtual ecosystems”

Present ecological state

Conceptual model for assessingthe ecological state of an ecosystem (cf. RHP)

Present ecological statePresent ecological state

Present ecological state (PES) The current state of affairs! - How much does the

current state differs from the natural state Expressed in terms of the following components:

Physical integrity/Drivers Geomorphology Hydrology Physico-chemical integrity

Biological integrity/response Ecostatus

Integrated state

Description of PES

Score % Class Description

90-100 A Unmodified or approximates natural conditions closely

80-89 B Largely natural with few modification

60-79 C Moderately modified

40-59 D Largely modified

20-39 E Seriously modified

0-19 F Critically modified

Ecological categories

A

Unhealthy

Not sustainable

Healthy

Sustainable

Biological integrity

Threshold

Score % Class Description

90-100 A Unmodified or approximates natural conditions closely

80-89 B Largely natural with few modification

60-79 C Moderately modified

40-59 D Largely modified

20-39 E Seriously modified

0-19 F Critically modified

F E BCD

Tools we use?

What do you need to assess the ecological integrity of an ecosystem?

Effective tools to measure the “health” of rivers at scales large enough to be useful for management.

These tools should be comprehensive, sensitive and quantitative tools (indicators) that are able to integrate and assess the conditions of each of the mentioned components (physical, chemical & biological) of an ecosystem.

Why are chemical analyses not enough? The results reflect the

conditions at the exact time of sampling.

It is impossible to measure all different chemical substances.

Some of the most toxic substances occur in minute quantities, often below detection limits (Day, 2000).

Chemical measures cannot be assumed to reflect the health of biota.Chemical measures cannot be assumed to reflect the health of biota.

“Integrators” of information

Biological communities: Reflect overall ecological

integrity (chemical, physical & biological)

Integrate the effects of different stressors in the catchment – aggregate impact

Integrate the stresses over time & provide an ecological measure of fluctuating environmental conditions.

Patterns in community response to stress are used to

determine biological integrity & ecological function

Ecological Indicators (Tools)

The tools (indicators) used for assessing the complex variables that constitutes river health need to be:

Ecologically based Efficient Rapid Consistently applicable in

different regions

Ecological indicators (Tools)

Indicator species Resident communities (e.g. fish, invertebrates)

reflect (or integrate) chemical & physical impacts in a time-related manner, and are therefore regarded as good indicators of overall biological integrity.

Macro-invertebrates Good indicators of localised conditions Integrate effects of short-term env variations Sampling relatively easy, requires few people and

inexpensive gear Minimal detrimental effect on resident biota. Macro-invertebrates abundant in most streams.

Fish

Good indicators of long-term effects & broad habitat conditions

Fish assemblages represents various trophic levels.

Env requirements & life-history of (relatively) fish well-known

Quantitative Indices

Interpretation of results obtained by means of biomonitoring.

The information obtained by biomonitoring should be simplified to be of use to resource managers, conservationists & the public.

A biological index integrates and summarises the biological data within an indicator group.

Biological indices therefore quantify the condition of river health with a numeric output.

State of the Modder River

SASS5

The value of biomonitoring

Is it appropriate technology?

Biomonitoring is good for: Surveillance of the

general ecological state of aquatic systems

Assessment of impacts (before & after)

Audit of compliance with ecological objectives or regulatory standards

Detection of long-term trends in the environment

Biomonitoring is good for:

To integrate information…

To provide strong scientific support in the absence of a full understanding of properties and interactions of complex systems being assessed

As an element of environmental management and an NB method (tool) in determining the state of the aquatic environment.

To summarize: Biomonitoring is used to track, evaluate and

communicate change in the condition of living ecosystems as a result of human impacts.

Biomonitoring, therefore, identifies ecological risks that are NB to human health and well-being

The goal is not to document and understand ALL the variation that arises in natural systems.Limitations:

Not useful as early warning system!

Difficult to account for natural variables!

Sampling labour intensive & time-consuming!

While science thrives on good questions,management needs GOOD ANSWERS,

as quickly and cheaply as possible.

It’s a trade-off betweenSPEED and ACCURACY

In conclusion: