Northwestern Hawaiian Islands Connectivity
Ecosystem Monitoring Studies
Coral Health Assessment Program
Maps and Data
Science Management Integration and Communications
Science Terms Glossary
Mapping cumulative human impacts
The Research Problem
Managers are often faced with needing to make tough but informed decisions about what threats and areas to prioritize to best protect the world’s fragile reefs. With so many different types of human activities now impacting the oceans, it is hard to figure out which are having the most impact where. It is also hard to compare very diverse types of threats, such as pollution and sea level rise – the first smothers reefs and can cause some fish and mammal deaths, and the latter causes loss of shallowest habitat. Which is worse? It depends where you are on the reef and how extensive each is. Our project systematically evaluates the ecological impact of all human impacts to all habitat types in the Northwestern Hawaiian Islands to help answer some of these questions.
We included spatial data over multiple years for alien species occurrences, bottom fishing, lobster trap fishing, ship-based pollution, ship strike risks, marine debris, research diving, research equipment installation, research wildlife sacrifice, and several anthropogenic climate change threats i.e., increase in ultraviolet (UV) radiation, seawater acidification, the number of warm ocean temperature anomalies relevant to disease outbreaks and coral bleaching, and sea level rise. We used another index to measure the cumulative impact of human activities for each pixel in the map.
The resulting cumulative impact map demonstrated that although the Northwestern Hawaiian Islands are some of the most protected reefs in the world they are sheltered still vulnerable to global threats. Temperature stress was found to be the most serious threat, followed closely by the other climate change effects, marine debris and risks of pollution and grounding from ship traffic.