Reef Madness

Last week we explored the dynamic barrier islands, a great place for wildlife and a popular vacation destination. This week, we venture beyond the island into the coral reefs just offshore. As an avowed landlubber, I'll probably never get to see a coral reef for myself, but I'll live vicariously through myself telling you all about them.

Coral reef (Smithsonian)

Coral reefs are hard, rocky structures made of the skeletal remains of what was once living coral. Corals are a marine animal, not a plant, and the best-known form a symbiotic relationship with algae. Because algae needs sunlight for photosynthesis, many coral reefs are found in clear, shallow water. Cold water corals that live in the deep sea. Without sunlight, these organisms filter feed plankton. Because of their inaccessibility, we are still learning about them.

Coral polyps (NPS)

The most popular corals are the shallow ones, because they are relatively easy to reach. Scuba diving, snorkeling, and even glass bottomed boats bring humans right to the biological hot spots. People are drawn to coral, not just because of the beauty of the coral itself, but the amazing biodiversity found within the reef. Fishes, crustaceans, sponges, anemones, and countless other sea creatures call the reef home. The coral structure provides hiding places for mobile critters and anchorages for sessile ones. Hiding places benefit predator and prey alike- they provide somewhere to hide from bigger fish, or place to launch a quick strike at an unsuspecting meal.

Coral reef (NPS)

Cold water corals provide the same habitat and ecosystem, and may be even more important than their shallower counterparts. Most sea life can be found near the coast and relatively shallow. Corals in the deep sea for a sort of island in an area that is otherwise mostly devoid of life.

Deep sea cold water coral (Joint Nature Conservation Committee)

Like just about every ecosystem in the world, coral reefs are in trouble. Coral is dying as sea temperatures and carbonic acid levels rise. The algae component of the coral either dies or evacuates in a process known as coral bleaching. Some corals show some resistance to slightly warmer temperatures. Research into this is continuing. If you ever get a chance to explore coral reefs, either by boat or underwater, remember to look but don't touch.
This week's information comes from NOAA and the Smithsonian Institute.

Species of the Month

Don’t laugh at November’s Species of the Month. Although it lends its name to the fiction hometown of the Griffin family in TV’s The Family Guy, the northern quahog (pronounced co-hog) is a real animal. A species of clam, it was likely eaten at the first Thanksgiving in 1621. The Pilgrims neglected to save a menu for posterity, so we’ll never know for sure. Will your Thanksgiving meal include any seafood? 

Northern quahog (NOAA Fisheries)

Scientific name: Mercanaria mercanaria 

Kingdom: Animalia (animals) 

Class: Bivalva (bivalves) 

Order: Veneroida (saltwater and freshwater molluscs) 

Range: East coast of North America from Gulf of St. Lawrence to Gulf of Mexico 

Habitat: Estuarine intertidal mudflats 

Lifespan: 30 years or more, a separate Arctic species was found to be 507 years old 

Diet: Zooplankton and phytoplankton 

Predators: Moon snails, oyster drills, whelks, rays, skates, shorebirds, humans 

Conservation Status: No special protection. 

Northern quahog (Chesapeake Bay News)

Quahogs are commercially harvested. In addition to a food source, they act as a natural filter by feeding. They filter feed through a siphon that extends from the shell. Plankton and pollutants go in, clean water comes out. Quahogs are mobile, although they don’t move much. A single foot at the base of the shell holds it in place in the mud or sand and can quickly dig in to avoid predators. It can also be used to move laterally. Quahogs reproduce by releasing sperm and egg cells into the water, where they randomly meet and fertilize. Within two weeks, the quahog larvae have formed a foot and shell and anchored to the substrate. Ocean currents aid in fertilizing the eggs and dispersing the larvae. This week's information comes from University of Michigan's Animal Diversity Web.

Migration

The days are getting shorter and cooler. Leaves are starting to turn and fall. Winter is approaching, and many animals are have already begun their seasonal migration. While some hibernate to avoid unfavorable seasonal habitat conditions, others move temporarily to more suitable habitat.

Migrations occur across all different animal classes: birds do it, and so do mammals, fish, insects, reptiles, amphibians, and crustaceans. Even some people do it. Florida and Arizona get plenty of snowbirds from up north every winter. More traditionally, nomadic tribes still exist in Africa and Asia living as they have for centuries.

We’re an ecology blog, not an anthropology blog so let’s forget about nomads for a minute. Perhaps the most visible migrations here in America are those of birds and monarch butterflies. Birds migrate to and from pretty much everywhere. Some stay within North America when migrating while others fly from pole to pole. Others, of course, are somewhere in between.

We’ll use the Baltimore oriole as an example of avian migration. They arrive in the eastern US from Central and northern South America in April and May. This is their breeding ground. They begin nesting right away and eggs usually hatch in June. Southern migration begins as early as July and has peaked by September.

Baltimore oriole (NPS)

Monarch butterflies journey to Mexico in a multi-generational migration. Northern monarchs go south to the oyamel fir trees in the mountains of central Mexico. Millions of them cover the trees. After winter, they head north again, laying eggs on milkweed plants. Caterpillars hatch in a few days and eat the plants before forming a chrysalis. A new butterfly emerges and continues the northward journey, stopping at milkweed to lay eggs and start the hatching and migrating process over again. The northernmost monarchs are able to return to Mexico in a single journey.

Monarch butterfly

The pronghorn in Wyoming migrates vertically. It moves from summer grounds in Grand Teton National Park about 150 miles south to lower elevation in the sagebrush habitats of the Green River area. This is North America’s longest mammal migration.

Pronghorn

Not all migration is seasonal. Zooplankton in the ocean migrate vertically through the water column on a daily basis. At night the move toward the surface, and by sunrise they are headed back to the briny deep. While a journey of hundreds or thousands of feet might not seem like much to you, keep in mind that these tiny critters probably can’t see as far as the other end of a yardstick.

Zooplankton (Nature International Journal of Science)

Fall migration is happening now. Who is moving through your neck of the woods?

This week's information comes from:

Journey North (Baltimore oriole)

National Geographic (monarch butterfly)

Wildlife Conservation Society (pronghorn)

Nature International Journal of Science (zooplankton)