NOAA's Marine Debris Blog

Keepin' the Sea Free of Debris!

Survey and Assessment of Marine Debris in Chesapeake Bay Tributaries: Mysterious Debris!


manta trawl

The manta net being towed behind the R/V Laidly. We owe a huge thank you to the NOAA Cooperative Oxford Laboratory (especially Captain Skip and Matt!) for all of their help with the surface water sampling.

How BIG of a problem is marine debris? A lot of research is being done around the globe in order to figure that out (for more information, check out the program from the recent Fifth International Marine Debris Conference: One contribution by the NOAA Marine Debris Program (MDP) is our marine debris monitoring and assessment project. The goals of this project are to 1) develop protocols for assessing the types and quantities of marine debris on shorelines and throughout the water column and 2) collect data to compare marine debris abundance, composition, distribution, and movement on regional, national, and global scales. This type of data is important for establishing baseline information from which changes in abundance – perhaps due to new regulations or outreach programs designed to prevent marine debris – can be detected.

cod end

An example of the contents of the cod end (the end of the manta net where material that doesn’t pass through is retained) after a trawl near the mouth of the Patapsco River. The Patapsco is an urban watershed that drains Baltimore Harbor. Look at all of the plastic sheeting on the 5 mm sieve at the upper part of the photo.

Over the past two years the MDP has developed and tested methods for assessing the types and quantities of marine debris (larger than 2.5 cm) on shorelines and floating in surface waters. This summer we’ve ramped up our efforts and are completing regular sampling on four tributaries of the Chesapeake Bay. We are testing the hypothesis that land-use characteristics (for example whether it is an urban or rural watershed) have an effect on the abundance of marine debris. However, as with all environmental research, there are a number of other factors that introduce variability in our data, for example, storm events, tides, winds, and current patterns. The more information we collect, the more likely we are to be able to tease apart these factors and detect trends in our data.

There is always a certain degree of the unknown when we’re out there observing what types of debris end up on our shorelines and floating in our rivers. Where did that inflatable monkey come from? Did someone have a picnic on the beach and leave their plastic knives, forks, straws, and soda cans behind? Or did all of that debris wash in from the bay? Most times it is impossible to tell. However, we’re hoping to solve one mystery with a bit of “CSI Marine Debris” and the help of our readers (see the photos below). We’ve been finding a number of caps of various colors on shorelines (mainly at the mouth of the Patapsco) since at least the summer of 2010. We’ve been asking around but nobody seems to know exactly what they are. They have threads on the inside so we think they are the cap to a valve or container of some sort. Any ideas? If so, PLEASE send us an email at We’d love to figure out where they’re coming from and stem the tide of these mystery items into the bay. Thanks! 


mystery debris

Author: NOAA Marine Debris Program

The NOAA Marine Debris Program envisions the global ocean and its coasts, users, and inhabitants free from the impacts of marine debris. Our mission is to investigate and solve the problems that stem from marine debris, in order to protect and conserve our nation's marine environment, natural resources, industries, economy, and people.

4 thoughts on “Survey and Assessment of Marine Debris in Chesapeake Bay Tributaries: Mysterious Debris!

  1. I’m pretty sur they are the tips to needles. We find them all of the time when we clean up the wetland adjacent to Fort McHenry – an artifact of our times

  2. They are wire connectors or “wire nuts”. they are threaded inside to screw two wires together. they are used in every type of electrical work.

  3. Pingback: Monitoring and Assessment: using standard techniques to measure our progress | NOAA's Marine Debris Blog

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