Identifying Waste Currents in Hawai’i
Waste that accumulates along shorelines greatly impacts marine environments when entangled and ingested by fish, birds, turtles, marine mammals, and invertebrates. Furthermore, the leaching of degrading plastics increases the levels of persistent organic pollutants in the water. These negative environmental impacts also affect human communities, which experience decreases in tourism, increases in cost of cleanup, threats to safety for ships, and other public health hazards. While many shorelines around the world are experiencing debris accumulation problems, the Hawaiian Islands are particularly impacted due to the proximal location of the "Great Pacific Garbage Patch" in the North Pacific Gyre, which contains degraded plastic pieces in an area that is double the size of Texas.
A team of researchers from the University of Hawai'i (Hilo and Manoa) and Hawai'i Wildlife Fund concluded a study that modeled potential ocean current pathways that carry and disperse waste originating from Hawai'i Island. The study, published in Marine Environmental Research, involved two parts: the placement of debris-retention booms placed at each of the two waterways in Hilo to take account of the amount and types of debris runoff, and the release and tracking of degradable wooden drifters from four locations - two well-populated areas of Hilo Bay and Kailua-Kona and two less-populated areas of Pohoiki and Kaulana - to approximate the movement of Hawai'i-sourced debris.
The two booms captured a total of 29.9kilograms (kg) of anthropogenic debris over a 205-day period, 73.6% of which was plastic by weight. Surface runoff from rainfall events were identified as a major factor in debris entering the waterways and ocean. However, the amount of debris collected in the duration of the study pales in comparison to the 16 metric tons of debris removed from Kamilo Point per year on average since 2003. Located near the southern end of Hawai'i Island, the researchers were particularly interested in identifying the source of debris accumulating along the 15-kilometer coastline of Kamilo Point.
The researchers were able to successfully identify probable marine pathways that debris originating from Hawai'i Island could take en route to Kamilo Point by tracking wooden drifters. However, a majority of the wooden drifters (78%) were recovered within 25 km of the release points with fewer drifters recovered on the coast of other islands. Thus, the study was able to verify the researchers' observations that a majority of the debris accumulating around the coastlines of Hawai'i are of non-Hawaiian origin, having travelled further distances than expected.
Buoyant debris, such as capped plastic bottles, is easily transported to various far-reaching places with grave environmental impacts. The authors state the importance of local waste-management and consumer choice in reducing the use and waste of plastic products. While raising community awareness in Hawai'i is a great start to addressing the proliferation of coastal debris, global efforts in preventing anthropogenic debris from entering marine environments are needed in order to prevent the degradation of marine and coastal ecosystems. The phrase, "not in my backyard," does not apply when garbage enters the ocean since the ebb and flow of currents have no boundaries.