Week 7- Benthic Habitat Quality

Why do we need habitat quality assessment

40-60% population live within 100km from coast

Reliant on coast for so much

Particularly in UK as coast is disproportionate to land mass

Underpinned by various processes and influence lots of ecosystem processes/functions

Is this good or bad habitat qualtity

Shows impact of sewage/contaminants

No macrofauna or oxygen

All microbial

How do Darnell and Soniat (1981) define good habitat quality - Environmental manager pov

State in which components and processes remain well within specified limits of system integrity selected to assure that there is no diminution in the capacity of system

How do Karr and Dudley (1981) define good habitat quality - Holistic ecosystem management

Water body should have ability to support and maintain a balanced, intergrated adaptive community of organisms that have a species composition diversity and functional organisation comparable to that of a natural environment

How do Karr et al. (1986) define good habitat quality

Biological system can be healthy when inherent potential is realised, stable condition, capacity for self repair when pertubated is preserved and minimal external management needed

How does Constanza (1992) define good habitat quality - combines previous defintions

Summarised conceptual attributes that a definition should include: homeostasis, disease absence, diversity/complexity, stability/resilience, vigour or scope for growth

Describe the conceptual model of change in habitat quality in a managed and unmanaged system

Managed

1. Stress takes place

2. Increasing stress= decreasing ecosystem integrity

3. Then recovery/ integrity increases as something implemented by humans

Unmanaged

1. Uplift in system when stress first added

2. Tactilation

3. Then becomes too much stress

What do we compare habitat quality to/ what is the baseline

The condition that is representative of a group of minimally disturbed sites organised by selected physical, chemical and biological characteristics (Reynoldson, 1997)

What would you measure in order to determine benthic habitat quality

Macrofauna, richness,altitude, content in top layer, anthropogenic inputs

Why measure macrobenthos

• Generally sedentary

• Lifespan allows us to integrate and reflect sources os stress over time

• Often reside at sediment- water interface where pollutants concentrate

• Taxonomically diverse consist of species with differing stress tolerances

How do we go about examining coastal stressors

Using the hierarchy of targets

What does the hierarchy of targets focus on

Sustainable development, ecological integrity, reduction of marine pollutants, estuarine nitrogen concentration

What do monitoring programmes tend to do

Detect ecologically significant change in habitat quality relative to a reference

What are the the different approaches used for habitat quality assessment

Approach that focuses on environmental factors:

• Identification of environmental factors that influence benthic community structure

Approach that focuses on systems response

• Evaluate the health of the benthic community as an indication of environmental pertubation

*Can also use an intergrated approach

What are the 3 elements of ecological integrity

Physical, chemical and biological integrity

What were Karr and Yoder’s ideas on ecological integrity model

Karr- model was inadequate

Yoder- proposed an alternative, with an areas of biological integrity whereby chemical and physical overlap

What is a way of mapping benthic quality

Substrate and then habitat maps

What are the approaches used to habitat quality assessment

Many different approaches used, not a new concept

What are the 8 factors that Karr described as the reason for the rise of non-biological assessment

1. Dominance of reductionist viewpoints

2. Limited legal/regulatory programs

3. Lack of clear biological integrity definition

4. Region based quantitative definitions of ecological health

5. Indices to assess biological integrity

6. Standardisation of field methods

7. Linking field measurements to enforceable management options

8. Need for coast effective approaches

What os the metric approach

Development of spatial habitat characterisation fuelled by management demands for reductionist approach

1. Complex set of data

2. Reduction to single site-specific numeric score within good/bad continuum

3. Meets legislative requirements and operational budgets

What is the index of biotic integrity (IBI)

• Conceived by Karr for stream fish

• Requires single sample that represents fish species compostion

• Then you add up scores based on how the study site deviates from each metric

What is a good and bad biotic integrity score

Good is 60 - excellent

Bad is 0 - no fish

What were Diaz et al., observations

• Reference sites varied from 1 to 234

• Fauna was majority macrobenthos

• Taxonomic resolution at species level was highest

What is the organism sediment index (OSI)

Business model of past 50 years

What is the benthic quality index (BQI)

Long equation

Expands to include tolerance

Further subdivision of P-R model

Should we protect species or habitats

No idea- debated by terrestrial ecologists