D6 Sea-floor integrity

Sea-floor integrity is at a level that ensures that the structure and functions of the ecosystems are safeguarded and benthic ecosystems, in particular, are not adversely affected.

The seafloor makes up over 70% of the Earth's surface and constitutes a key compartment for marine life. A broad variety of habitats exist both inside and above the seabed, depending on substrate nature, depth, hydrodynamics and other local environmental conditions. This patchiness is reflected on the variety of associated sedentary and mobile species, which define benthic and necto-benthic assemblages that are still poorly know in certain areas (namely most of the deep sea and partially the mid to lower shelf). 

Given the pending threats upon the critical goods and services the seafloor provides, maintaining its integrity is necessary to preserve marine biodiversity and living resources. Therefore, the Marine Strategy Framework Directive addresses seafloor integrity in its Descriptor 6. This concept reflects the safeguarding of the characteristics (physical, chemical and biological) of the sea-floor, including natural spatial connectivity, upon which a healthy structure and functioning of marine ecosystems depend.
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D6 Commission Decision (EU) 2017/848 of 17 May 2017
Sea-floor integrity is at a level that ensures that the structure and functions of the ecosystems are safeguarded and benthic ecosystems, in particular, are not adversely affected.
Criteria
D6C1 – Primary: Spatial extent and distribution of physical loss (permanent change) of the natural seabed.

D6C2 – Primary: Spatial extent and distribution of physical disturbance pressures on the seabed.

D6C3 – Primary: Spatial extent of each habitat type which is adversely affected, through change in its biotic and abiotic structure and its functions (e.g. through changes in species composition and their relative abundance, absence of particularly sensitive or fragile species or species providing a key function, size structure of species), by physical disturbance. Member States shall establish threshold values for the adverse effects of physical disturbance, through regional or subregional cooperation.

D6C4 – Primary: The extent of loss of the habitat type, resulting from anthropogenic pressures, does not exceed a specified proportion of the natural extent of the habitat type in the assessment area.

D6C5 – Primary: The extent of adverse effects from anthropogenic pressures on the condition of the habitat type, including alteration to its biotic and abiotic structure and its functions (e.g. its typical species composition and their relative abundance, absence of particularly sensitive or fragile species or species providing a key function, size structure of species), does not exceed a specified proportion of the natural extent of the habitat type in the assessment area.
Glossary
Sea-floor is defined as a key compartment for marine life. It includes both the physical and chemical parameters of seabed (e.g. bathymetry, roughness (rugosity), substratum type, oxygen supply, etc.) as well as the biotic composition of the benthic community. Different kinds of habitats for sedentary and mobile marine species are formed inside and above the seabed. 

Integrity is interpreted as comprehending both (i) natural spatial connectivity (avoiding unnatural habitat fragmentation or connectivity), and natural ecosystem processes functioning in their characteristic ways. 

Not adversely affected means that the cumulative effect of pressures associated with human activity are at a level that ensures the ecosystem maintains its respective components (structure) along with its natural levels of diversity, productivity, and dynamic ecological processes (functioning). Levels of disturbance (intensity, frequency, and spatial extent) must be at a level that ensures a dynamic recovery potential is maintained. 

Recovery means that the impacted seafloor attributes show a clear trend towards their pre-perturbation conditions, and the trend is expected to continue (if pressures continue to be managed) until the attributes lie within their range of historical natural variation. Benthic communities are not static entities, and thus recovery does not re-quire that the ecosystem attributes return to their exact prior state. 

Rapid must be interpreted in the context of the life histories of the species and natural rates of change in the community properties being perturbed. For some seafloor habitats and communities, recovery dynamics from perturbation would require multiple decades or more, and in such cases management should strive to prevent perturbations. 

Impairment of an ecological component occurs if the ecological consequences of the direct or indirect perturbations extend widely through the ecosystem in space and/or time, or if the normal ecological linkages among species act to extend and amplify the effects of a perturbation rather than to dampen its effects.