A High Concentration Of Coastal Development And Population Density Results In Cumulative Impacts to the Ecosystem
The majority of visitor accommodations, local human population, and infrastructure are along the coastline in Hawaiʻi. This high concentration of coastal development and population density results in most human activities taking place in and adjacent to the nearshore environment.
These are cumulative impacts that disrupt natural ecological processes and reduce ecosystem health, function, and resilience. Understanding the spatial distribution, intensity, and overlap of human activities and their cumulative impacts is essential for effective marine management and preserving the myriad ecosystem services generated by coral reefs.
The maps presented in this section are from a study and represent the first-ever assessment of spatial variation in cumulative impacts to nearshore ecosystems for the Main Hawaiian Islands.
This study generated a database of 16 individual human stressors and led a panel of experts to determine nearshore habitat vulnerability to each of these stressors. The three dominant nearshore marine habitat types in Hawai‘i are, in order of expert-assessed vulnerability (highest to lowest):
- coral reefs,
- rocky areas, and
- sandy or muddy areas.
Experts rated the vulnerability of habitats to each stressor based on four vulnerability criteria (frequency, trophic impact, percent change, and recovery time). Experts also determined their certainty for each rating. The cumulative impact score for any area (100 m grid cells) is based on the vulnerability weighted sum of the individual stressor intensities for the habitat type present in that area. Cumulative impact scores were normalized from 0-1 with values greater than or equal to the 99th percentile set to 1.
These maps represent a baseline of comprehensive human impact information for Hawai‘i and will be updated as new datasets and improved information on nearshore stressors become available. Please see Lecky (2016) for more detailed information on the maps and how they were generated. Certain map layers (e.g. fishing and sedimentation) are described in additional detail in Wedding & Lecky et al. (2018).