Raiders of the East Coast

Asian Shore Crab (Hemigrapsus sanguineus)

Range and distribution

• Shore crabs are native to the Asian coast from Russia to Hong Kong. 
• They have been introduced to the East Coast of the USA.
• These crabs are now found in waters from Maine to North Carolina.

How Did the Shore Crab Get to America?

• It is not well known how, but many agree on one theory:
• The crabs were most likely released by a foreign ship discharging ballast.
• Ballast water is used to stabilize unloaded cargo ships.
• The ships release the water when they are refilled at their destination. 
• Unfortunately, this often releases non-native species into new habitats.

When Did ASian Shore Crabs Arrive?

• The Asian shore crab was first recorded in the US in 1988.
• The Location was in Cape May County, New Jersey.
• Shore crabs are now well established along the Northeastern shoreline.

Competition with other species

• The Asian shore crab competes with several native species.
• These include Blue crabs, Rock Crabs, and American lobsters.
• Shore crabs also compete with Green crabs, another non-native species.
• This is a Blue crab, a major competitor of the Shore crab.

Impact on Habitat

• Shore crabs have a very broad diet and thus effect existing food webs.
• Shore crabs crowd out native crabs and other organisms.
• Because of their appetite, these crabs out-compete others for food.
• Shore crabs are highly adaptable to many aquatic habitats.
• This crab is an Atlantic rock crab, a competitor of the Shore Crab.

Methods of Control

• Tracking the spread of Asian shore crabs
• Researching ballast water management on ships
• Encouraging the public to eat the crabs, many recipes exist!

Saving the Sea Cow

West Indian Manatee
(Trichechus manatus)

Range and Distribution

• West Indian manatees are found in and near the Caribbean.
• They inhabit shallow, warm coastal waters, which include estuaries.
• Manatees cannot live in water with a temperature lower than 68 F.
• In summer, they have been found as far north as Cape Cod!

Characteristics

• Adults grow to around 10 ft. long and can weigh almost a ton.
• Manatees eat aquatic plants such as sea grass.
• Manatees' heads are broad and have whiskers.
• Their flippers and tails are large, round, and paddle-like.

Reproduction

• Females give birth to only one calf after 12-14 months of gestation.
• The calves stay with their mothers for the next two years.
• Manatees can mate at any time of the year.

Population Size

• The Florida manatee subspecies has at least 4,000 individuals.
• The Antillean manatee subspecies has less than 2,500 adults.

Why are Manatees Endangered?

• Hunting and illegal poaching in South America
• Environmental factors (cold water, red tide)
• Collisions with boats

Manatee Conservation

• The number one cause of manatee death in Florida is boat collisions.
• Local, state, and federal gov'ts rely on public education programs.
• Public awareness and programs have proved effective.
• Manatees are protected by several acts and laws.
• The Florida manatee is Florida's official state marine mammal.