Sec.22a-426-5. Biological condition gradient model

(a) The Biological Condition Gradient Model is a model that describes how ecological attributes change in response to increasing levels of stressors. In accordance with the Biological Condition Gradient Model, as the level of stress gets progressively greater, the biological communities, which start out in a natural condition, begin to change as they respond to the stress.

CONNECTICUT BIOLOGICAL CONDITION GRADIENT MODEL

>

(b) The ecological attribute changes are categorized into tiers, as follows:

(1) Tier 1 - Native condition is such that the native structural, functional and taxonomic integrity is preserved; ecosystem function is preserved within the range of natural variability.

(2) Tier 2 - Minimal changes in the structure of the biotic community and minimal changes in ecosystem function are such that virtually all native taxa are maintained with some changes in biomass or abundance; ecosystem functions are fully maintained within the range of natural variability.

(3) Tier 3 - Evident changes in structure of the biotic community and minimal changes in ecosystem function due to loss of some sensitive-rare taxa; shifts in relative abundance of taxa but sensitive-ubiquitous taxa are common and abundant; ecosystem functions are fully maintained through redundant attributes of the system.

(4) Tier 4 - Moderate changes in structure of the biotic community with minimal changes in ecosystem function due to replacement of some sensitive-ubiquitous taxa by more tolerant taxa, but reproducing populations of some sensitive taxa are maintained; overall balanced distribution of all expected major groups; ecosystem functions largely maintained through redundant attributes.

(5) Tier 5 - Major changes in structure of the biotic community and moderate changes in ecosystem function are such that the sensitive taxa are markedly diminished; conspicuously unbalanced distribution of major groups from that expected; organism condition shows signs of physiological stress; ecosystem function shows reduced complexity and redundancy; increased build-up or export of unused materials.

(6) Tier 6 - Severe changes in structure of the biotic community and major loss of ecosystem function are such that there are extreme changes in structure; wholesale changes in taxonomic composition; extreme alterations from normal densities and distributions; organism condition is often poor; ecosystem functions are severely altered.

(Effective October 10, 2013)