Session Chairs: Captain Charles Moore, Algalita Marine Research and Education; Shelly Moore, Southern California Coastal Water Research Project (SCCWRP)

This session is focused on how persistent marine debris accumulates in oceanic gyres and is affecting marine organisms and community structures. This is key to continuing the discussions of what can be done to alleviate the increased debris accumulation stress.

The movement of debris from land-based sources, as well as debris input from the ocean-based fishing industry into oceanic current systems have been shown to result in the accumulation of marine debris in subtropical gyres. Subtropical gyres serve essential roles as nursery areas for many pelagic species, including sea turtles. The accumulation of persistent plastic debris in these areas serves to skew the species distribution. Species that utilize the available and accumulated debris will find these conditions to be favorable, whereas others will not. Modelling in these areas show how the debris move with the oceanic currents into the gyre accumulation areas. In addition, monitoring by organizations, such as Algalita Marine Research and Education, has documented substantial increases in the quantity of debris in an area known as the “Eastern Garbage Patch.” This area has been shown to be a heavy accumulation zone within the north Pacific subtropical gyre. Recent surveys have shown that certain coastal species such as sea anemones are increasing in these areas. The accumulation of debris in subtropical gyres also affects foraging opportunities for seabirds, such as the albatross. Analysis of the stomach contents of Laysan albatross on Midway and Kure Atolls show that bottle caps are the most common ingested debris item.

These examples show how much work remains to be done to address the changes in species composition and survival in areas of high debris accumulation. With the recent monitoring in remote areas of the Arctic showing the presence of persistent marine debris, this problem has been elevated to even more of a global scale, with clear international implications. The Sixth International Marine Debris Conference is a perfect forum for continuing the discussions on how to address this significant environmental problem. The goal of this session will be to bring together those doing research in these areas, not only to report on the research, but also to strategize moving forward in order to develop methodologies and recommendations for actions to address the overarching problem.




Subjective Impressions from a denizen of the Gyres

presenting: Charles Moore (Algalita Marine Research and Education, United States); authors: Charles Moore (Algalita Marine Research and Education, United States)

Over the last 20 years, on a dozen research voyages, I have spent several months in the North and South Pacific Subtropical Gyres, searching for heavy accumulations of marine debris. In my presentation, I will summarize the subjective impressions of a researcher who has dedicated his time and resources to understanding and mitigating the ocean’s plastic load. These include:

1) The shock of discovering for the first time the quantity of plastics in surface trawls in 1999 vs the vague feeling of something amiss in sightings in the same area in 1997.

2) The appearance and patchiness of visual sightings of marine debris

3) The associated marine life in the garbage patches

4) Diving day and night in the heavy debris zones

5) Collection methods for sampling living creatures and marine debris

6) Changes in the extent of high debris concentrations in the North Pacific Accumulation Zone


Anticyclonic eddies increase accumulation of microplastic in the North Atlantic subtropical gyre

presenting: Alexandra ter halle (Université Paul Sabatier, France); authors: Alexandra ter halle (Université Paul Sabatier, France), Emile Perez (), Erik Van sebille (Grantham Institute, Imperial College London, UK)

There are fundamental gaps in our understanding of the fates of microplastics in the ocean, which must be overcome if the severity of this pollution is to be fully assessed. The predominant pattern is high accumulation of microplastic in subtropical gyres but there are some high spatial heterogeneities regarding sea surface microplastic concentrations that were not rationalized. During the sea campaign 7th Continent in the North Atlantic subtropical gyre we sampled to mesoscale eddies (one cyclonic and the other anticyclonic). Using in situ measurements were compared with data from satellite observations and models. We show how microplastic concentrations were up to 9.4 times higher in the anticyclonic eddy explored, compared to the cyclonic eddy. Satellite-observed chlorophyll-a was also more abundant inside the anticyclonic eddy (on average 30%). Although our sample size is small, this is the first suggestive evidence that mesoscale eddies might trap, concentrate and potentially transport microplastics. As eddies are known to congregate nutrients and organisms, this phenomenon should be considered with regards to the potential impact of plastic pollution on the ecosystem in the open ocean.


Impacts of plastic pollution in oceanic islands off the North Atlantic subtropical gyre

presenting: Christopher Pham (IMAR-Institute of Marine Research and MARE—Marine and Environmental Sciences Centre, University of the Azores, Horta, Portugal, Portugal); authors: Christopher Kim Pham (IMAR-Institute of Marine Research and MARE—Marine and Environmental Sciences Centre, University of the Azores, Horta, Portugal, Portugal), Yasmina Rodríguez (IMAR-Institute of Marine Research and MARE—Marine and Environmental Sciences Centre, University of the Azores, Horta, Portugal), Ressureição Adriana (IMAR-Institute of Marine Research and MARE—Marine and Environmental Sciences Centre, University of the Azores, Horta, Portugal), Rios Noelia (IMAR-Institute of Marine Research and MARE—Marine and Environmental Sciences Centre, University of the Azores, Horta, Portugal), Frias João (IMAR-Institute of Marine Research and MARE—Marine and Environmental Sciences Centre, University of the Azores, Horta, Portugal), Carriço Rita

Subtropical gyres are recognized to be important zones for the accumulation of marine debris in the oceans. As a result, global risk assessments predict that marine organisms found in oceanic gyres experience an increased likelihood of debris ingestion. The Azores archipelago is a remote group of nine volcanic islands located off the North Atlantic Subtropical Gyre. Plastic pollution is ubiquitous in the archipelago but its impacts for the marine environment and local communities are poorly known. In this presentation, we provide an overview of recent research efforts dedicated to studying the issue in this remote region of the North Atlantic. Surveys aimed at quantifying plastic debris on the seafloor, along the island’s coastlines and in the water column demonstrate a high abundance of debris in the region. Furthermore, results on monitoring plastic ingestion by different components of the food-web confirm a high exposure of marine fauna to these pollutants. Finally, preliminary results on the socio-economic impacts associated with marine debris also reveal significant costs for local populations. Overall, the information obtained during the past years highlight the vulnerability of oceanic archipelagos to the increased amount of debris accumulating in oceanic gyres.


Midway Atoll (Northwestern Hawaiian Islands) Marine Debris Accumulation Project

presenting: Kevin O’Brien (NOAA Pacific Island Fisheries Science Center, United States); authors: Kevin O’Brien (NOAA Pacific Island Fisheries Science Center, United States)

Since 2011, NOAA’s Pacific Island Fisheries Science Center (PIFSC) Marine Debris Project has conducted shoreline plastics removal operations at Midway Atoll in the Northwestern Hawaiian Islands (NWHI) within the Papahānaumokuākea Marine National monument (PMNM). Due to the extremely remote nature of the NWHI and the expense of conducting work there, PIFSC’s focus had previously remained on the removal derelict fishing gear (DFG) in order to mitigate the entanglement hazard for the critically endangered Hawaiian monk seal and threatened green sea turtle. However, for the last six years, PIFSC has been able to also dedicate resources to shoreline plastic survey and removal at Midway Atoll due to its accessibility and resources to handle and process collected debris.

In an effort to determine the level of accumulation, PIFSC designed a shoreline study on Eastern and Spit Islands on the southern side of Midway Atoll. Those islands have been sampled, surveyed, and cleaned annually since 2013, providing a four-year data set. Additionally, a project to expand this study to five of the other NWHI was piloted this summer in partnership with NOAA PIFSC Protected Species Division. This presentation will review the experimental design and discuss preliminary analysis of debris accumulation.


Mini-Gyres showing up across the State of Hawaii

presenting: Kahi Pacarro (Sustainable Coastlines Hawaii, United States); authors: Kahi Pacarro (Sustainable Coastlines Hawaii, United States)

Mini-gyres are showing up across the state of Hawaii whereas their prevalence prior was one of rarity. This increased occurrence is the result of society’s overuse of plastic and an unsustained cleanup effort. It is our hope with this presentation to bring light to this new common phenomenon, share what we’ve learned thus far, and to encourage new ideas to predict, clean, and use them to inspire consumer behavior change.

When faced with these mini-gyres, the physical immenseness is daunting. Appearing like cauldrons of colored confetti, these mini-gyres focus in bowls formed by coastline topography, winds, waves, and currents. From what we’ve been able to observe, these mini-gyres have a certain predictability that could lead to a better understanding of the larger gyres as a whole.

Cleaning these mini-gyres up range from simple to extremely difficult but very few of these cleanups have ever been attempted. The video of this one being cleaned up on a remote island in the Hawaiian chain shows the challenges and opportunities surrounding mini-gyre cleanup operations (video here:

It is our hope that our inclusion into this session can provide a springboard for others to help in the understanding of these mini-gyres which lead to a reduction in their occurrences and the simplification of their cleanups. In addition we aim to share what we’ve learned thus far and how we’ve been able to turn this microplastic into a commodity.


Gyres North & South. A Partnership on both sides of the Equator to Mitigate Marine Debris.

presenting: Raquelle de Vine (Algalita Marine Research and Education, New Zealand); authors: Raquelle de Vine (Algalita Marine Research and Education, New Zealand)

Less than ten years ago it was unknown whether the Southern Ocean subtropical gyre’s accumulated marine debris or not. That the South Pacific subtropical gyre accumulates marine debris was confirmed in January 2017 during Algalita Marine Research and Education’s 6month South Pacific Research voyage. 3 weeks of which we spent documenting the extent and concentration of marine debris in the gyre.

During this time I obtained surface samples and observed high concentrations of plastics in the surface zone. The alarming results highlighted a need to address the high input and sources of the debris and the importance of communicating this to the South Pacific Nations in a time critical manner. In order to contribute to the mitigation of the increasing problem of accumulating marine debris in the South Pacific subtropical gyre I have obtained the support of Algalita Marine Research and Education to inaugurate a sister organization in my home country of Aotearoa New Zealand.

In my presentation I will highlight the need for a sister organization of Algalita in the South Pacific and what our roll will be, now and in the future with specific focus looking at possible collaborations with other South Pacific nations . I will discuss how we plan to address mitigation of the problem of accumulation in the subtropical gyre with emphasis on Aotearoa New Zealand’s contribution and look into some of the challenges facing the implementation of effective mitigation measures.