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 2010/477/EU
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 objective is that human pressures on the seabed do not hinder the ecosystem components to retain their natural diversity, productivity and dynamic ecological processes, having regard to ecosystem resilience. The scale of assessment for this descriptor may be particularly challenging because of the patchy nature of the features of some benthic ecosystems and of several human pressures. Assessment and monitoring needs to be carried out further to an initial screening of impacts and threats to biodiversity features and human pressures, as well as an integration of assessment results from smaller to broader scales, covering where appropriate a subdivision, sub-region or region ( 19 ).

D6 Documents
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.