Marine Debris Science

Marine debris can be any size from a boat or a dock that washed away in a storm, to a tiny particle that is hard to distinguish from a grain of sand. These small particles are called microplastics. Microplastics are plastic pieces that are less than 5 millimeters in length (about the size of a pencil eraser). Some microplastics are manufactured to be this size, such as microbeads from health and beauty products, while others are the result of larger plastic items breaking down in the environment. Some particles are so small that they cannot be filtered out through our water treatment facilities, such as microfibers from washing clothing made from synthetic materials. Microplastics are so small, it is nearly impossible to remove them from the environment. The best strategy is to prevent them from entering it in the first place.
Microbead in Sand Sample
Microplastic in Toothpaste
Microfiber
Recent studies have found small ocean animals such as fish, mussels, and zooplankton with microplastics in their tissue and stomach. If these build up in the stomach, they interfere with digestion and can cause animals to die from starvation. Another concern is that chemicals have been shown to naturally cling to plastic particles, meaning that a lot more harmful substances may be ingested that could lead to sickness or disease.
Widespread microplastic monitoring is just beginning to occur around the world. DNREC has started research initiatives to determine the amounts of microplastics in the sand, surface waters, and sediments. Scientists have begun by collecting samples in Kent County to determine if microplastics are already present in Delaware's coastal environment and provide baseline data to compare for future studies.
The graph to the right shows the number of entangled animals that were found and recorded during Delaware's Coastal Cleanup Day from 2016-2018. These animals were land- and aquatic-dwelling, ranging from foxes to birds to fish. In most cases, the animals were dead at the time of siting on the cleanup dates. There were even a couple of instances where Atlantic sturgeon, an endangered species, were identified in the debris. The uptick in the 2017 numbers is due to a large group of horseshoe crabs that were massed together in fishing line. Entanglement data helps to stress the importance of keeping our inland, coastal, and marine environments clean.
Fishing Gear
Abandoned fishing gear is one of the deadliest types of marine debris that ocean-dwelling animals can come across. Lost gear, such as fishing nets and crab pots, can entangle and trap organisms long after their intended use period. Gear can become derelict or get lost from being swept away by storms, having lines cut accidentally by passing boat propellers, or losing floats because of improper pot rigging.
Derelict Crab Pot Removal
Blue crabs, a popular catch in Delaware, are affected by these lost "ghost" pots that continue to catch crabs without anyone tending them. Additionally, crab pots, if not rigged properly, can be a particular problem for diamondback terrapins because the bait used to attract crabs also attracts the turtles. Once they enter the pot, they can't get back out, which means they can't go up to the surface for air.
DNREC received a grant from the National Oceanic and Atmospheric Administration Marine Debris Program to identify and remove ghost crab pots in the Delaware Bay. The project focuses on the identification and removal methods for abandoned commercial crab pots in the bay.
This video explains how to properly rig your crab pot for recreational crabbing and highlights requirements that are specific to Delaware. These requirements in the regulations may differ from surrounding states, so it's important to make sure you are aware of the laws of the areas where you set your pots.
These regulations help prevent crab pots from becoming derelict and also protect wildlife, including diamondback terrapins that could get trapped inside an abandoned pot.

Page reviewed 4/4/19