A study in Nature Ecology and Evolution, led by the Smithsonian Environmental Research Center (SERC) and the University of Hawai'i (UH) at Mānoa, reveals that a remarkable diversity of coastal marine invertebrates has successfully colonized the high seas. These species are now able to thrive and reproduce in the open ocean, significantly influencing the composition of the floating community.
In their study, the research team discovered a wide range of coastal species, spanning various taxonomic groups and life history traits, on more than 70 percent of the plastic debris they surveyed in the eastern North Pacific Subtropical Gyre. Notably, the debris contained a higher abundance of coastal species compared to open ocean species, indicating a significant contribution of coastal marine invertebrates to the floating community in the high seas.
"Lead author Linsey Haram, a research associate at SERC, highlights that this finding implies a rapid shift in the established biogeographical boundaries among marine ecosystems that have existed for millions of years, all due to the accumulation of floating plastic pollution in the subtropical gyres."
The "neopelagic communities," or floating communities in deep ocean waters, were recently discovered by the research team. To gain a deeper understanding of the ecological and physical processes that govern these communities on floating marine debris, the Smithsonian Environmental Research Center (SERC) and the University of Hawai'i (UH) at Mānoa joined forces to form a multi-disciplinary team called the Floating Ocean Ecosystem (FloatEco) team. While UH Mānoa focused on assessing physical oceanography, SERC examined the biological and ecological aspects of the study.
The FloatEco team conducted their study by analyzing 105 plastic samples collected during The Ocean Cleanup's 2018 and 2019 expeditions in the North Pacific Subtropical Gyre, which covers a significant portion of the northern Pacific Ocean. The field work involved the participation of individual volunteers and non-governmental organizations to collect the samples, highlighting the collaborative effort in obtaining the data for the study.
Lead author Linsey Haram expressed their astonishment at the findings, stating, "We were extremely surprised to discover 37 different invertebrate species, which typically inhabit coastal waters, on the plastic debris. This number was more than triple the species found in open waters, and what's even more remarkable is that these coastal species were not only surviving on the plastic, but also reproducing." Haram further noted that the team was intrigued by how readily coastal species colonized new floating items, including their own instruments, and that this observation warrants further investigation.
Co-author Gregory Ruiz, who is a senior scientist at SERC, explained that the results of the study indicate a significant shift in the distribution and dispersal of coastal invertebrates. He stated, "Our findings suggest that coastal organisms are now able to reproduce, grow, and persist in the open ocean, forming a novel community that did not exist before and sustained by the ever-expanding sea of plastic debris." This insight challenges previous notions of barriers to the distribution and dispersal of coastal species, representing a paradigm shift in our understanding of marine ecosystems impacted by plastic pollution.
Although it was already known that organisms, including certain coastal species, could colonize marine plastic debris, the recent study has shed light on a previously unknown phenomenon: established coastal communities can persist in the open ocean. This discovery highlights a new human-induced impact on the ocean, revealing the scale and potential consequences of this phenomenon that were not previously understood. It underscores the need for continued research and action to address the growing issue of plastic pollution and its far-reaching effects on marine ecosystems.
Nikolai Maximenko, co-author and senior researcher at the UH Mānoa School of Ocean and Earth Science and Technology, pointed out the proximity of the Hawaiian Islands to the North Pacific garbage patch. He explained, "The debris that breaks off from this patch makes up the majority of debris that reaches Hawaiian beaches and reefs." In the past, the islands were protected by the long distances from coastal communities in Asia and North America. However, the presence of coastal species persisting in the North Pacific Subtropical Gyre near Hawai'i is a game changer. It indicates that the islands are at an increased risk of colonization by invasive species, posing a new threat to the fragile marine ecosystems of the region. This underscores the urgent need for measures to mitigate plastic pollution and prevent the spread of invasive species in the marine environment.
Ruiz emphasized that their study reveals a significant knowledge gap and limited understanding of the rapidly changing open ocean ecosystems. He stressed the urgent need for a substantial enhancement of high-seas observing systems, including comprehensive measurements of biological, physical, and marine debris parameters. This underscores the importance of investing in advanced monitoring and research efforts to improve our understanding of the complex dynamics of the open ocean and to inform effective management strategies for the conservation and protection of marine environments.
Source: https://www.soest.hawaii.edu/