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September 10, 2016 | By:  Jessica Carilli
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Microplastic in the ocean

While cleaning up files on my computer, I came across this image I put together a few years ago from a trip to New Zealand. It struck me as a great example to use to discuss some of the challenges presented by ocean plastic. Plastic in the oceans is arguably one of the most important and pervasive environmental problems today.

Ocean plastic is problematic for a number of reasons, but primarily because marine animals eat it. Some of the most famous examples are seabirds and turtles, which can starve to death when their digestive tracts fill with toothbrushes, plastic bags, and other material. Creatures like turtles and marine mammals can also become entangled and drown in large items like phantom nets and bags. But even small creatures eat ocean plastic, because by far the largest numerical proportion of ocean plastic falls in small size fractions. Small plastic particles may come from washing clothing, the initial plastic beads used to melt down and create plastic goods called nurdles, or might be fragments of larger plastics that have broken down.

Eating plastic can lead to a number of negative consequences. For instance, zooplankton experimentally offered microplastic beads and algae ate less algae overall, and some retained plastic particles in their guts for longer periods that normal food particles were retained. Similarly, feeding experiments conducted this summer by NSF-sponsored Research Experience for Undergraduate student Eliya Baron-Lopez of UC San Diego and intern Rowan Yelton at the New England Aquarium (NEAq), together with Juanita Urban-Rich of UMass Boston and Randi Rotjan of NEAq showed that corals readily ingest microplastic particles, and can re-ingest particles that are expelled. Thus, animals like corals may be expending energy to ingest, expel, and reingest particles that ultimately provide no nutritional benefit and may prove harmful. Filling up on plastic instead of food can lead to reduced growth, fecundity (reproductive output), or starvation.

Aside from clogging up the digestive tracts of marine life, plastic also has a potentially more sinister side: it tends to adsorb pollutants like PCBs from the water column, thus acting as a potential vector to move pollutants from the water column into the food chain. Aside from potentially devastating effects on marine life, human health may also be compromised. For example, one study found that European consumers could be ingesting approximately 11,000 microplastic particles annually through shellfish consumption, with unknown impacts on human health. Tiny plastics are a huge problem because (1) their high surface-area-to-volume ratio and chemical makeup increases the likelihood of pollutant adsorption, (2) they are ubiquitous and creatures that eat particles in that size fraction tend not to be the brightest on the planet (thus lacking strong discriminatory powers), and (3) there is no known way to clean them up.

The small particle size of microplastics means that they can't just be sieved out of the water without also sieving out all of the marine life (like the above planktonic snail or juvenile mussel) or other natural particles (like the above bit of pumice, on which marine life may be living). In addition, while many plastics float, many other plastic particles are neutrally or negatively buoyant and are found within the water column or on the ocean bottom.

So, if we can't realistically clean up the existing plastic pollution without killing everything in the oceans, what's to be done? A recent study found that small particles tended not to disperse very far from their sources on land, possibly due to biofouling and subsequent settling to the bottom. It's therefore clear that the most obvious place to start is not in deploying expensive and failure-prone cleanup devices in the middle of the ocean, but instead preventing plastic pollution at our shores. Mr. Trashwheel is one adorable and effective method to capture macroplastic. Microplastic pollution can be prevented by not using personal care products that use them (you'll have to be a careful consumer if microplastics haven't yet been banned where you live), and wearing fabrics made of natural fibers. That fleece in your closet? Repurpose the fabric in a way that it won't need to be washed anymore and replace it with clothing that doesn't shed fibers, or keep an eye out for new clothes washing technologies that prevent microplastic pollution.


Choy, C. A., & Drazen, J. C. (2013). Plastic for dinner? Observations of frequent debris ingestion by pelagic predatory fishes from the central North Pacific. Marine Ecology Progress Series, 485, 155-163.

Cole, M., Lindeque, P., Fileman, E., Halsband, C., Goodhead, R., Moger, J., & Galloway, T. S. (2013). Microplastic ingestion by zooplankton. Environmental Science & Technology, 47(12), 6646-6655.

Van Cauwenberghe, L., & Janssen, C. R. (2014). Microplastics in bivalves cultured for human consumption. Environmental Pollution, 193(6), 5e70.

Wilcox, C., Van Sebille, E., & Hardesty, B. D. (2015). Threat of plastic pollution to seabirds is global, pervasive, and increasing. Proceedings of the National Academy of Sciences, 112(38), 11899-11904.

Woodall, L. C., Sanchez-Vidal, A., Canals, M., Paterson, G. L., Coppock, R., Sleight, V., Calafat, A., Rogers. A. D., Narayanaswamy B. E., & Thompson, R. C. (2014). The deep sea is a major sink for microplastic debris. Royal Society open science, 1(4), 140317.

September 06, 2016 | By:  Sara Mynott
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Lost At Sea? Here's Where To Find Shelter.

In my last post, I discussed some of the problems caused by derelict pots and traps in the ocean. The fate of lost fishing nets is not always so dire. As nets drift in the current, they can ensnare unsuspecting victims, but they can occasionally provide shelter for an assortment of young creatures, which cluster under the floating raft, just as they would a raft of seaweed or piece of driftwood.

While eventually, the net will sink to the depths of the sea, while it remains at the surface, it can create a refuge for the ocean's younger inhabitants. Juvenile fish, which out in the open would expose themselves to the eyes of predators, take cover under the disused mesh, darting between the ropes and revelling in relative safety. For anything larger, the nets present a serious problem.

Living animals can also create an unusual refuge in the otherwise open ocean. Some jellies are used for cover by Pacific butterfish and have a host of other hitchhikers. There are even animals that shelter in the bum of another species! Pearlfish reside in the rear passage (the cloaca) of sea cumbers, sheltering in the safety of their bum and nipping in and out to feed.

Whatever the refuge, it's vital to stay vigilant, as things may not always be as safe as they seem. The sargassum fish, for example, are brilliant mimics of the weed in which they live. They drift in rafts of sargassum and wait for their food to come to them. They lie in waiting, ready to snap up any young whippersnapper that gets too close. Their incredible camouflage allows them to snap up their prey when it swims within only a few centimetres of their mouth!


1) Clip of a pearlfish and a sea cucumber. Credit: BBC via YouTube.

2) A sargassum fish (Histrio histrio) from the Sargassum Sea. Credit: Eric Heupel via

August 24, 2016 | By:  Sara Mynott
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To Catch More Crabs, Catch Lost Crab Traps

Every year, vast quantities of fishing gear is lost at sea - from nets to lines, pots and traps. The traps lay derelict on the seafloor, catching wandering crustaceans, which, once caught, may not escape and could die imprisoned in the discarded trap. This can have a huge impact on populations - for the species the trap was intended for, and for others.

The traps are primarily lost during storms, during which they can be ripped from their tether or can loose their surface marker, rendering them incredibly difficult to find. When baited, these traps can attract piles of crabs that flock from afar to catch a free meal. But even when empty, the structure these pots provide in an otherwise barren landscape attracts inhabitants.The number of animals caught in a trap varies hugely with trap design and with species interactions, as some defend their territory, reducing the number of successful newcomers. Despite this, they remain effective and are responsible for huge losses from crustacean populations and from fisheries.

Just how huge, has been demonstrated by scientists from William & Mary's Virginia Institute of Marine Science. In a six-year program to remove lost pots in Chesapeake Bay, commercial crabbers were employed to find and recover derelict gear over the winter - outside of their fishing season. Together, they removed some 34,000 derelict crab pots and - at the same time - harvests increased dramatically.

"We estimate that crabbers harvested about 60 million more crabs due to the ghost-pot removals," says study co-author Donna Bilkovic. "That's one extra blue crab each time a pot is retrieved - crabs that would have otherwise been captured or attracted to the now absent derelict gear."

But was it worth the cost of employing crabbers to catch lost traps? The project cost $4.2 million to run, and generated over $21 million in harvest value. It's a no-brainer. "The benefits far outweighed the program's total cost," says Andrew Scheld, another of the study's authors.

Ghost gear is most likely to accumulate in areas that are heavily fished. The study showed that by focusing recovery efforts on these areas, the return on investment could be even greater.

Chesapeake Bay is the largest estuary in the US and one of the world's major shellfish fisheries, but it's not the only area affected by derelict gear. Wherever fishing takes place, lost pots and traps are a problem.

Ghost gear is a global phenomenon, but it needn't stay that way. Removing even 10% of derelict pots and traps from major crustacean fisheries around the world could increase landings by nearly 300,000 tonnes, which would boost profits by $800 million a year. With that kind of financial incentive, ghost gear should soon be a thing of the past.


Sheld, A. M., Bilkovic, B. M. and Havens, K. J. (2016). The dilemma of derelict gear. Scientific reports 6, 19671.


1) Fishing gear. Credit: Chesapeake Bay Program via Flickr

2) Tagged blue crabs. Credit: Chesapeake Bay Program via Flickr

3) Surveying the sea. Credit: Chesapeake Bay Program via Flickr

4) Blue crab. Credit: Chesapeake Bay Program via Flickr

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