A map of human impacts to a “pristine” coral reef ecosystem, the Papahānaumokuākea Marine National Monument

Abstract

Effective and comprehensive regional-scale marine conservation requires fine-grained data on the spatial patterns of threats and their overlap. To address this need for the Papahānaumokuākea Marine National Monument (Monument) in Hawaii, USA, spatial data on 14 recent anthropogenic threats specific to this region were gathered or created, including alien species, 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. These data were combined with habitat maps and expert judgment on the vulnerability of different habitat types in the Monument to estimate spatial patterns of current cumulative impact at 1 ha (0.01 km 2 ) resolution. Cumulative impact was greatest for shallow reef areas and peaked at Maro Reef, where 13 of the 14 threats overlapped in places. Ocean temperature variation associated with disease outbreaks was found to have the highest predicted impact overall, followed closely by other climate-related threats, none of which have easily tractable management solutions at the regional scale. High impact threats most tractable to regional management relate to ship traffic. Sensitivity analyses show that the results are robust to both data availability and quality. Managers can use these maps to (1) inform management and surveillance priorities based on the ranking of threats and their distributions, (2) guide permitting decisions based on cumulative impacts, and (3) choose areas to monitor for climate change effects. Furthermore, this regional analysis can serve as a case study for managers elsewhere interested in assessing and mapping region-specific cumulative human impacts.

Assumptions, challenges, and future directions in cumulative impact analysis

“…Consistent ecosystem response.-The development and application of the vulnerability weights that define how a habitat or ecosystem responds to a particular stressor (Halpern et al 2007, Teck et al 2010) requires a fundamental assumption that all locations (within the same ecosystem type) respond the same way to a stressor, and that any given location responds the same at all points in time. This issue can partly be addressed by dividing habitat types into finer classifications known to respond differently to stressors (for example, in coral reefs one can map fore reef, reef crest, and reef slope at different depths; e.g., Selkoe et al 2009), but this can only be done to a point before it requires every single pixel of habitat to be uniquely classified. This assumption is thus one of necessity and data limitation.…”

Marine Spatial Planning in a Transboundary Context: Linking Baja California with California's Network of Marine Protected Areas

“…Recently, other aspects have been included for the design of a network of MPAs. As an example, cumulative human impact maps (e.g., Halpern et al, 2008Halpern et al, , 2009Selkoe et al, 2009;Ban et al, 2010;Micheli et al, 2013) have been used to prioritize habitats in good condition (Klein et al, 2013), and management surrogates (Balmford et al, 2004;Naidoo et al, 2006) to quantify the enforcement costs (Davis et al, 2015).…”

Widespread Dispersal of the Crown-of-Thorns Sea Star,Acanthaster planci, across the Hawaiian Archipelago and Johnston Atoll

“…The reefs of the MHIs are anthropogenically impacted from sewage outflow [1][2][3], alien invasive algae [4][5][6], overfishing [2,7], and nutrient discharge [8], whereas the NWHIs have remained relatively pristine [7]. Fish communities and biomass in the NWHIs are unparalleled to the MHIs [7], and in terms of ranking overall "health", the NWHIs have retained their biological richness and value compared to the MHIs [9][10][11].…”

“…Currently under protection as the Papahānaumokuākea Marine National Monument, the NWHIs remain shielded from most direct threats induced by human activities such as commercial fishing, military use, and tourism [11]. To inform ecosystem-based management in both the Monument and the reefs in the MHIs, it is necessary to know the direction and magnitude of connectivity across 2 Journal of Marine Biology the archipelago.…”