9 BENTHIC HABITAT QUALITY Flashcards
As habitat quality changes, we can expect a change in … and, consequently, … processes, … and services.
biodiversity
ecosystem
functioning
Good habitat quality definition from an environmental standpoint:
The state in which the … and processes remain well … the specified … of system integrity selected to assure there is no … in the capacity of the … to render its basic … to society.
components within limits diminution system services
Good habitat quality from a biological standpoint:
a water body should have the ability to support “a …, integrated, adaptive … of organisms having a species …, diversity and … organisation comparable to that of … habitat of the region.
balanced community composition functional natural
Good habitat quality from an ecological health standpoint:
a biological system… can be considered … when its inherent … is realised, its condition is …, its capacity for self-… when perturbed is …, and … external support for management is needed.
healthy potential stable repair preserved minimal
Costanza 1992 pointed out that habitat quality is a normative concept and broadened requirements of a definition to include several conceptual attributes:
- homeostasis
- absence of disease
- diversity or complexity
- stability or resilience
- vigour or scope for growth
- balance between system components
What are the stress effects of 1. DNA 2. Cell 3. Tissue 4. Organism 5. Population 6. Ecosystem?
- Mutations
- Cell death, disordered proliferation and differentiation, neoplastic transformation
- Functional defects, malformations, tumours
- Reduced viability, reduced fertility
- Reduction of population size, local extinction
- Reduction of species diversity
Reference conditions = pre-established … that exist for a … range of representative … and/or have been … over time as a … .
the condition that is … of a group of … disturbed sites organised by selected …, chemical and … characteristics
criteria wide sites gathered baseline
representative
minimally
physical
biological
ASSESSING COASTAL STRESSORS
Diagnosis of an … condition within an ecosystem includes the assessment of … and symptoms as well as lab tests like … tests, analytical …, and … tests
similar to medicine, the goal of an ecosystem assessment is to determine if an … condition exists, and identify the … of the stress
prognosis is determined through … models based on a history of … diagnoses as well as on … studies
abnormal signs toxicity chemistry bioaccumulation
abnormal
causes
predictive
previous
scientific
WHY MEASURE THE MACROBENTHOS?? (6)
- benthic macrofauna are generally sedentary
- the lifespan of many species allows community structure to integrate and reflect sources of stress over time
- many species reside at the sediment-water interface where many pollutants concentrate
- macrobenthic communities are taxonomically diverse, consisting of species that exhibit diff tolerances to stress
- Rhoads-Pearson-Rosenberg-Gray model of succession provides detailed understanding of how benthic communities work. Organism-sediment relations particularly well understood
- methods of sampling benthos have a long and proven history, and equipment is readily available and accessible
General problem of all ecological analyses is the complexity of the system.
Ecological measures must represent complex conditions in a strongly condensed & readily understandable form.
Reaching a desirable ecological condition must balance requirements from a wide range of actors & stakeholders.
What is the hierarchy of environmental parameters that policy from the broadest objective to what’s practical on the ground?
Models/targets
Guidelines
Quality objectives
Quality standards
Which processes dominate physical substrate in sediment flats, mussel beds and coral reefs?
(abiotic or biotic)
sediment flats: ABIOTIC properties dominate physical substrate
mussel beds: BIOTIC properties
coral reef: BIOTIC properties
Many metrics, approaches and conceptual developments for benthic habitat quality assessment originated in freshwater systems.
8 main classes of assessment:
- indices
- multimetrics & rapid assessment techniques
- physio-ecological assessment
- catchment-scale assessment
- ecosystem components assessment
- assemblage/community assessment
- process based assessment
- non-taxonomic assessment
Pro’s and cons of indices of biological integrity:
pro’s = convenient system capable of assessing quantity, quality and functional value of ecosystem
con’s - covarying and collinear variable concerns, lack of justification, inconsistencies in rationale and lack of testing
What is the indices of biological integrity?
- includes 12 measures summarising SPECIES COMPOSITION, TROPHIC COMPOSITION, FISH ABUNDANCE & CONDITION
- number rating assigned to each metric based on deviating strongly from, intermediately from or approximating expectation (1, 3, 5) based on comparison to regional reference site, historical records or standard.
- sampling site then assigned to 1 of 6 quality classes, with 60 = a site without perturbation
Gradients of environmental change & succession are well known and studied in benthic systems and form a natural rationale to underpin the formulation of benthic habitat quality assessments & metrics.
Both Rhoads and Rosenberg developed similar benthic assessments:
- ORGANISM-SEDIMENT INDEX (OSI)- reflects the apparent mean redox potential discontinuity depth in the sediment, the presence or absence of sedimentary methane, dissolved oxygen immediately above the sed-water interface, & successional stage.
- BENTHIC HABITAT QUALITY BHQ & BENTHIC QUALITY INDEX BQI
