Habitat diversity is a measure of the number and types of habitats that are found within an area. Habitat heterogeneity is defined as the spatial arrangement of those habitats. High habitat diversity and heterogeneity help to increase the successful movement of individuals, nutrients, and important food sources between habitat types; increase species diversity; and increase food web stability.
(e.g., nursery, spawning, foundation)
(e.g., anchor, burial, water quality)
Most human activities that occur in the ocean have multiple impacts and habitats may be negatively affected by multiple impacts. Consider the number and types of impacts associated with the proposed activity and how many impacts affect each habitat in order to assess the likely impacts to the diversity and heterogeneity of habitats in the area.
(e.g., rare vs. common habitats, habitat size, location)
Habitat distribution can be patchy and some habitats may be rare but fundamentally important to the system. Consider the distribution and arrangement of habitats at a variety of spatial scales (e.g., local and regional) to determine if the impacts from an activity are likely to negatively affect a significant portion of a habitat.
Evaluate the duration and frequency of each impact to habitats (e.g., short vs. long term impacts; light vs. heavy impacts):
Quantify the duration and frequency of each impact to habitats
Assess appropriate levels of duration and frequency of each impact
(e.g., nutrient source, aggregation area)
Marine ecosystems are largely comprised of static habitats that are present throughout the year. However, there are also dynamic habitats that vary over space and time, including upwelling areas, nearshore fronts, and breeding aggregation areas. These dynamic habitats are important to marine ecosystems and often represent areas of high primary productivity and/or large aggregations of multiple species and trophic levels. When and where these dynamic habitats are located can influence the expected impact on the ecosystem.