Where does our garbage go?

May 13th, 2015

Pacific Garbage Patch Landfills are a common human solution for disposing of trash on land. But when trash is discarded into the ocean, where does it end up? Unfortunately, since most types of marine debris (plastics, glass, etc.) are not biodegradable, the waste ends up floating in the water. When trash is discarded into the ocean, it often becomes incorporated into physical ocean features such as currents and gyres. Human waste in the ocean is becoming a problem so large that giant, swirling vortexes of trash now exist in the Pacific Ocean. Commonly called the Great Pacific Garbage Patch, this vortex of trash actually exists as two smaller patches that are called the Eastern and Western garbage patches. They exist on opposite sides of the Pacific Ocean basin. These smaller patches are connected by the Subtropical Convergence Zone (a physical feature of the ocean impacted by the atmosphere), which acts like a conveyor belt to move trash across the Pacific. No one knows exactly how large these patches are or how much trash they contain. Some heavier trash may sink in the water column, but many smaller pieces break off and float on the surface. Tiny pieces of plastic called microplastics can accumulate so much that the water may become cloudy in appearance. According to a National Geographic article, up to 1.9 million pieces of microplastics have been found to accumulate in a square mile in the Great Pacific Garbage Patch. The Great Pacific Garbage Patch is perilous to all forms of marine life, from tiny microscopic plants and algae to sea turtles and marine mammals. If the Patch becomes so abundant that sunlight is blocked at the ocean surface, phytoplankton and algal species cannot receive the sunlight they need in order to undergo photosynthesis and reproduce. If this base of the marine food web is compromised, this means there is less food available for all other species, including seafood for human populations. Many larger marine species, such as birds and sea turtles, have been found deceased with trash from the Patch in their stomach and intestinal tracts. Toxins leeched from plastic materials kill animals after they are ingested. Although the Patch is a large problem and too big for any one person to clean, you can do your part to prevent it from getting any larger. Using less plastic materials, recycling more, and being vocal if you see anyone throwing trash into the ocean are all ways that you can help the effort to reduce the Patch. If more effort is taken to reduce the amount of waste we produce, then there is hope the Great Pacific Garbage Patch will not continue to grow and plague marine life.

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How long could plastic stay in turtles?

February 18th, 2015

We are already all too familiar with the interaction between plastics and sea turtles, but a new study has provided additional information about the interactions between plastics in turtles.

Researchers from Germany and Australia have looked at what happens to different types of plastic bags as they are passed through the digestive tract of a both green and loggerhead sea turtles. The scientists were particularly interested in noting the differences in degradation (if any) between the standard grocery store plastic bag, the degradable plastic bag, and the biodegradable plastic bag. No turtles were harmed in the experiment, since the digestive fluids were taken from recently deceased loggerhead and green turtles.

Not surprising, the standard plastic bag and the degradable plastic bag underwent no significant change. There were high hopes that the biodegradable bag would be significantly broken down, as the manufactures claim when composted the bags break down in only 49 days. After 49 days in the gastric fluids of green and loggerhead turtles, the biodegradable bags had barely broken down at all, in some cases as little as 3% in the loggerhead. The green turtles fluids did a slightly better job of digesting the biodegradable material (9%), probably due to their herbivore diet, allowing them to more efficiently break down cellulose.

Over 177 marine species have been recorded to ingest man-made plastics, including 86% of sea turtles. Due to the presence of papillae lining their esophagus, it makes it almost impossible for the turtles to regurgitate the bags leading to gut impactions and perforations. These sobering results, published by Muller C. et al in Science of the Total Environment further demonstrate that all bags pose significant risk to marine life.

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Getting to the Heart of the Matter

February 11th, 2015

On Valentine’s Day there is no escaping the hearts. They are on cards, decorating store windows, in emails, and so on. What better way to show our love of sea turtles than discussing sea turtle anatomy and physiology – in particular the heart.

Sea turtles, like most reptiles, have three-chambered hearts: two atria and one ventricle with a sinus venosus preceding the atria. Humans also have a sinus venosus, but only in early development – later it’s incorporated into the right atrium wall. The ventricle is comprised of three different parts:  cavum venosum, cavum arteriosum, and cavum pulmonae.

Clearly, there is a lot going on in the heart of a turtle, and while those scientific words may sound confusing, the way they work together produces incredible results. A UNCW researcher, Dr. Southwood, along with others conducted studies on heart rates and diving behavior of leatherbacks -the deepest divers of the sea turtle clan. Using an ECG she measured their cardiac activity while at the surface, while descending or ascending, and while at depth. Once the leatherbacks initiated a dive, their heart rate would immediately decline as they submerged. The rate would continue to slow and even reached as few as 1 beat per minute, indicated a physiological response to energy conservation.

These cardiovascular alterations indicate a species well adapted to time at sea, especially long periods of time under the waves. This is one more reason (as if we needed another) to appreciate those amazing creatures.

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Understanding the Mysteries of Loggerhead Migration

February 4th, 2015

For centuries humans have been trying to navigate the oceans. Early attempts by the Phoenicians relied on celestial navigation over 4,000 years ago, and as ship design advanced, so did the navigational materials from early compasses, sextants, and astrolabes to modern-day radar, sonar, and GPS. While humans have been striving for a more efficient way to plot a course through the global oceans, one of our tetrapod friends has been doing this successfully, long before ancient or modern technology evolved.

We have long know that sea turtles have some kind of mapping system allowing them to travel long distances, yet return to natal beaches. Hatchling loggerhead sea turtles take a transoceanic trip, swimming from nesting beaches to the subtropical Sargasso Sea. They remain in this subtropical gyre for several years to mature, and then return back to beaches to nest. Over the years we were able to discern that they can interpret magnetic cues to determine their latitudinal position, but that is only half the picture. How were they able to orient themselves along the east-west longitudinal gradients?

In a new article from Current Biology, researchers from Chapel Hill have now provided that answer. Loggerhead sea turtles apparently use a bi-coordinate map with magnetic cues providing both latitudinal AND longitudinal information. Using a large water pool with a magnetic control field, the researchers would alter the magnetic field to mimic either a Puerto Rican orientation or a Cape Verde Island orientation. By using these two locations on opposite sides of the Atlantic, they were testing to see if sea turtles would swim in the proper direction to reach the Sargasso Sea. And it seems they did: turtles with the Puerto Rican magnetic field swam northeast and turtles with the Cape Verde Island field swam southwest.

It is remarkable to think that the hatchlings popping out of nests along our coast have an advanced navigation system in their tiny bodies. It is an innate ability, not something that they learn from migratory experience. Reaching the Sargasso Sea is an extremely difficult endeavor as they have to avoid both natural and manmade threat, but it is comforting that there is something guiding them along this journey.

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Fish for the Future

January 21st, 2015

As fish stocks around the globe dwindle, people are turning to aquaculture to provide suitable protein resources. Aquaculture, in some form, has been around for thousands of years used by ancient Chinese, aboriginal Australians, and Polynesians on the Hawaiian Islands.  While traditional methods still exist, increasing use a technology, hormones, and other chemicals can pose harm to local habitats and requires some level of monitoring.

The National Oceanic and Atmospheric Administration (NOAA) has released a new Aquaculture Program with several priority areas including: science and research, regulation and policy, international activities, and outreach /education.  The overriding objective is to establish a strong, effective set of rules for marine aquaculture within the U.S. For years, we have trailed behind in the aquaculture industry, and with this initiative NOAA hopes to make the U.S. a world leader.

Currently the United States consumes almost 5 billion pounds of seafood annually; this includes shellfish as well as finfish. Globally, almost 50% of all consumption comes from aquaculture. Despite this high percentage, only about 5% of U.S. consumption comes from domestic aquaculture sources. Currently, we import about 84% of our seafood. This indicates areas open to considerable amount of growth in our own country, but requires guidelines to ensure that our coastal environments remain unaffected.

Some of the initiatives target alternative food development and stock assessment. Both of these areas could help the flagging fisheries, but also have the potential to cause deleterious effects to the local ecosystem without proper management. Currently the NOAA Aquaculture Program is open for public comment, click here to view the document.

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