Papahānaumokuākea

The major form of marine pollution both inside and outside of Papahānaumokuākea Marine National Monument boundaries continues to be marine debris (State Party of the United States, 2024). Although no commercial or recreational fishing is permitted in Papahānaumokuākea waters, derelict fishing nets and gear, plastics and other ocean-borne debris are concentrated by ocean currents and wash up on the reefs and beaches of the islands. Entanglement in marine debris has been identified as a major threat to the endangered Hawaiian monk seal. Debris entanglement also threatens sea turtles, seabirds, cetaceans and coral reef organisms. In addition, ingestion of plastics causes significant mortality in many seabird species. Estimates of marine debris impacts are almost 60,000 pounds accumulation per year (State Party of the United Sates, 2024). Since 1996, a large-scale effort to remove marine debris from the monument has resulted in 1,167 metric tons (more than 2 million pounds) of primarily derelict fishing gear and plastics removed. To combat the debris and mitigate its hazards, multiple partners collaborate on this removal mission every few years to clean debris from the World Heritage Site and its shores. The NOAA Marine Debris Program has been involved in this effort since the Program was established in 2006, and is now supporting efforts led by the National Fish and Wildlife Foundation and Papahānaumokuākea Marine Debris Project through funding provided by the Bipartisan Infrastructure Law (NOAA Marine Debris Program 2024).

The incidence of diseases affecting marine organisms is increasing globally, but the factors contributing to disease outbreaks remain poorly understood. The overall average prevalence of coral disease is quite low in the Northwestern Hawaiian Islands as compared to other coral reef areas (Aeby, 2006). Recent studies have begun to document these disease baselines in corals and other associated marine animals such as fish and sea turtles. In 2011, one site previously surveyed and monitored at French Frigate Shoals (FFS) had seen a significant reduction in the density of Acropora cytherea due to colonies dying from one of the growth anomalies and ‘white syndrome’ associated with the diseases found in the Northwestern Hawaiian Islands. Most other monitored sites have not seen significant reductions in densities of corals (Steven, 2012). No updated information has been identified on this subject.

Hazards to shipping and other forms of maritime traffic such as shallow submerged reefs and shoals are inherent in the Northwestern Hawaiian Islands. The region is exposed to open-ocean weather and sea conditions year-round, punctuated by severe storm and wave events in winter. Hence vessel groundings and the release of fuel, cargo, and other items pose real threats to the Northwestern Hawaiian Islands (Selkoe et al., 2008). Additionally, vessel traffic could also facilitate the introduction of invasive alien species. These threats are greatly reduced by the national and international maritime management measures in effect for this site. In April 2008, a designation by the International Maritime Organization (IMO), declared the waters of Papahānaumokuākea a “Particularly Sensitive Sea Area” (PSSA), implemented a mandatory ship reporting system and expanded and consolidated existing Areas To Be Avoided (ATBA) into four larger ATBAs (Papahānaumokuākea, 2012). While there is minimal vessel traffic to the islands, there has been a major increase in the use of the designated corridors for large commercial vessel passage between Lisianski and Pearl and Hermes (State Party of the United States, 2024).

Permits may be issued in one of six permit categories: research, education, conservation and management, Native Hawaiian practices, special ocean use, and recreation. The Monument Co-Trustees grant both single- and multi-year permits. Of the permitted activities, research and conservation and management received the most permits (Papahānaumokuākea Marine National Monument, 2019). Human presence is necessary to carry out resource management objectives and conduct necessary scientific and cultural research. Effectively tracking monument permits and the associated number of permitted vessel and permit related aircraft entries within the monument allows for accurate reporting of levels of human presence. The only location equipped to accept aircraft within the monument is Midway Atoll.

Some of the buildings on Midway date to 1903, with most of them dating to the period between 1939 and 1993, when the atoll was used as a U.S. Navy base. Studies conducted by the U.S. Fish and Wildlife Service and others between the late 1980s and 2009 showed that Laysan albatross chicks exhibited symptoms of lead toxicity, which causes their wings to droop and prevents them from developing the ability to fly and forage for food, leading to death. The studies found their exposure is likely related to ingestions of lead-based paint chips and soil contaminated with the chips, which the birds often pick up and place into their nests. One study estimated that eliminating the chick mortality from lead poisoning would increase the Laysan population at Midway in 50 years by as many as 360,000 birds over the projected population size without lead-based paint removal (U.S. Fish and Wildlife Service, 2011).

In the past, several of the islands and atolls of Papahānaumokuākea have been heavily inundated by terrestrial invasive alien species. Both Midway Atoll and Laysan Island have incurred multiple introductions, some of which transformed the landscapes. Some of the most invasive introductions were intentional during the days of guano mining, such as vegetation, rats, and rabbits that caused extensive damage. To date, rats and rabbits have been successfully exterminated in Papahānaumokuākea, but various other invasive alien species still affect the inhabited islands and atolls. The Midway Seabird Protection Project recently failed to eradicate house mice (Mus musculus) that attack albatrosses on Sand Island, the larger of the two islands that make up USA’s Midway Atoll in the North Pacific (Cooper, 2023). The number of invasive alien land plants in Papahānaumokuākea varies from only three introduced at Nihoa, to 249 introduced at Midway Atoll. Numerous efforts have been made to eradicate and restore the emergent lands to their native conditions, particularly at Laysan Island and Midway Atoll. Other management and restoration efforts are undertaken annually during the late spring through mid-fall field season. To prevent further importation of invasive plants, animals, and insects, mandatory quarantine protocols are enforced for any visitors to all the islands of Papahānaumokuākea, with the exception of Midway Atoll (Papahānaumokuākea Marine National Monument, 2009). On Sand Island invasive mouse predation has occurred among nesting Laysan albatross (U..S. Fish & Wildlife Service, 2018).

In 2006 a total of nine established marine non-indigenous species were known in the Monument (Godwin et al., 2006). As of March 2020, findings from the marine alien species inventory project have documented that there are potentially 61 non-indigenous species in the Monument. These non-indigenous species consist of two cryptogenic species of red algae, three species of fish and 56 species of marine invertebrates (Tsuda, et al., 2015, Godwin, et al., 2020). Invasive alien species may be introduced accidentally, such as with vessel discharge, marine debris, or aquaculture, or intentionally, as in the case of a few species of snappers, grouper, and algal species (PIFSC-CRED unpublished data.). To date, none of these species has caused significant problems in Papahānaumokuākea Marine National Monument. However, there are a variety of marine invasive species, particularly five species of algae in the main Hawaiian Islands, which if transported to the Papahānaumokuākea, could cause significant changes in species composition. A cryptogenic, invasive-like red macroalga, Chondria tumulosa, was first observed in 2016, and resighted in 2019, forming thick mats on the forereef of Manawai Atoll (also known as Pearl and Hermes Atoll) (Lopes et al., 2023). Subsequent expeditions revealed an increased abundance of this alga. The red alga was observed to form large, thick algal mats that were smothering corals and coral reefs with few other reef species surviving below the mats. Since then it has been identified in isolated areas at Kuaihelani (also known as Midway Atoll) and at Kure Atoll as well (Fumo et al. 2024, Hawaii Department of Natural Resources 2023, Papahānaumokuākea WHS report 2023). The pervasiveness of this alga remains a significant threat to biosecurity in Monument waters (National Marine Sanctuaries, 2019).

Projected sea level rise, combined with likely increases in storm and wave energy, indicate that there is a high likelihood of inundating low-lying islands within the property and increasing coastal erosion on all islands over the next 50-100 years [high confidence] (Wagner and Polhemus, 2016). Between 2009-2018 sea level has increased by as much as 10 mm in the southeastern portions of the Monument. Beach and coastal strand habitats are very likely to be lost as a result of sea level rise, storm inundation, and erosion with significant implications for endangered species that rely on these habitats for nesting and breeding, including monk seals, sea turtles, and seabirds (Wagner and Polhemus, 2016). On Oct. 3, 2018, Hurricane Walaka transited through the French Frigate Shoals as a category 4 hurricane with sustained winds of up to 125 mph and East island was 95% eroded, due to storm surge from Hurricane Walaka and nearby Trig island was also lost due to intensified wave activity, both of which serve as important habitat for the Hawaiian green turtle, Hawaiian monk seal and seabirds. Habitat dislocation has interfered with the level of pupping and nesting for months (Papahānaumokuākea Marine National Monument News, 2018). Papahānaumokuākea‘s globally important bird population are at risk from the loss and degradation of habitat, changes in prey availability, and direct impacts from changes in environmental conditions, particularly increasing land surface temperatures (Wagner and Polhemus, 2016).
Problems associated with increased sea surface temperatures have been reported in the Northwestern Hawaiian Islands. Sea surface temperature information obtained from NOAA demonstrated that water temperatures at Midway rose nearly two degrees centigrade over the usual summer maxima in August of 2002. Corresponding with this warm water event, substantial coral bleaching was observed—a process whereby coral colonies lose their colour due to the expulsion of symbiotic microscopic algae (zooxanthellae) from most coral tissues—on reefs at the three northwestern most atolls: Kure, Midway, and Pearl and Hermes. A similar thermal anomaly centered over Lisianski Island in 2014 resulted in significant bleaching in shallow waters and mortality of nearly four square kilometers of coral (NOAA 2024).

In 29 March 2011, the Japan Tsunami washed over large portions of the islands and atolls of PMNM. On Midway 110,000 Black footed and Laysan Albatross chicks were killed representing 22% of the seabird population. An additional 500-600 Black-foot Albatross chicks were killed at Kure Atoll. Tens of millions of dollars in structural damage were also done to Midway Atoll (Reynolds et al. 2017). The risk of such an event reoccurring is growing with climate changes and poses a high threat due to the significant possible consequence on the site's key attributes.

Uncharacterized, unlined landfills remain on some of these islands. Kure Atoll and French Frigate Shoals both have point sources of PCBs due to former U.S. Coast Guard LORAN stations. While the Coast Guard has mounted clean-up actions at Kure Atoll, elevated levels of contamination remain in island soils, nearshore sediment, and biota. The Navy also left landfills behind on Midway Atoll. Studies have shown that soil can constitute up to 30% of the material a bird consumes, and hence soil contamination from the above substances is a substantial threat to the bird populations (Hui and Beyer, 1998; Beyer et al., 1994). A 2016 remediation project was done at Kure Atoll to relocate carbon-treated contaminated soil from low elevation areas and is expected to minimize the future hazard of release through storms or erosive activities. Additionally, a 2018 study by the U.S. Environmental Protection Agency detected PCBs, PAHs, lead and other contaminants in soil and porewater at Tern Island at French Frigate Shoals from legacy dump activities. In 2018, Hurricane Walaka removed cement and sediment covering a former dump site and exposed potentially hazardous materials (Papahānaumokuākea Marine National Monument News, 2018). It is important to notice that military activity still occurs within the Monument boundary, even if minimal, and is exempted from required management approvals and permissions (State Party of the United States, 2024).