Shores

The two types of marine grasses found along our coast are the Eelgrass and Turtle grass. These grasses provided the foundation of an ecosystem not only by serving as producers but they also provide a nursery for the young invertebrate organism. In fact many of the fish that live in the reef grow to juveniles in the turtle grass. The stems and the roots of the grass hold the substrate in place and when the grass dies it falls, stabilizes the shoreline and provides nutrients for organism in the community. In the grass community you might find decorator crabs, mummichogs, hermit crabs, pufferfish, seahorses, brittle stars, worms, scallops and sponges.

Day 102.2

When we think of the coast, most of us think of a sandy beach ecosystem.

There are no large rocks or tide pools, but there are miles of sand made from quartz, feldspar, eroded shells and maybe even lava. Beaches are formed when this sand is transported towards the coast by longshore currents. The waves, tides and currents must be strong enough to wash away the silt and clay, but weak enough to leave the sand behind. In this ecosystem organisms cannot attach to any particular object and adapt by burrowing themselves in the sand or swimming around in the waves. Everything within a sandy beach ecosystem is moving. Even the beach itself changes continuously. Throughout the seasons, the waves rework the sand and even change the shape of the beach. Because of this constant movement, the sandy beach supports very few species, but these species occur in great numbers.Beach profiles are changed because of the drift associated with the movement of the water. When currents and tides are strong and sediment supply is low, beaches may begin to erode away. Beaches are very unstable. It has been estimated that a single grain of sand can move as much as 70 feet in one day! The profile of a beach is marked by three zones created by the tidal water levels and the shape of the shifting sand. The inland zone is the backshore which includes the base of the dunes and the high tide line. This is the area above the high tide line. This area supports the beach grass and birds. This is the area where most of us go to visit when we go to the beach. The middle zone is called the foreshore and marks the area between the high and low water levels. During the high tide, this area is submerged and clam worms, trumpet worms, bristle worms, giant cockles and fiddler crabs inhabit this area. At low tide, these organisms retreat to the safety of the soil or the receding waves. The last zone is referred to as the inshore zone. This is where the waves break along the coast of the beach and is marked by the low tide line. In this area, the organisms are always submerged, therefore allowing for the greatest variety. In this area one might find an array of clams, sand dollars, squid, sting rays, horseshoe crabs, zoo plankton and blue crab.Along these three zones, a beach profile typically contains many characteristic features.

Backshore

dune ridge – wind blown sands

berm – deposits from receding storm waves or spring high tide water levels

Foreshore

runnel – depression often filled with seawater

ridge – formed from wave action, broad gentle and sloping

low tide terrace – smooth low slope

Inshore

longshore bar – elongate and parallel to shoreline, submerged except during spring low tides

The shape of a beach depends on whether or not the waves are constructive or destructive, and whether the material is sand or shingle. Constructive waves move material up the beach while destructive waves move the material down the beach. On sandy beaches, the backwash of the waves removes material forming a gently sloping beach. On shingle beaches the swash is dissipated because the large particle size allows percolation, so the backwash is not very powerful, and the beach remains steep. Cusps and horns form where incoming waves divide, depositing sand as horns and scouring out sand to form cusps. This forms the uneven face on some sand shorelines.

The rocky shore is an intertidal zone made up of rocks at an ocean’s shore. Living in this environment is very challenging. At high tide, the organisms must face the impact of the crushing waves and the hard rock; while at low tide, the organisms may become hot and dry. Within this environment there are extreme fluctuations in temperature, salinity and the availability of oxygen. There are three zones found within the rocky shore ecosystem:  the splash zone, the intertidal zone and the subtidal zone.

The subtidal zone is submerged in water at all times, while the intertidal zone is only submerged during high tide. The splash zone only receives water during high tide when the waves crash against the rocks. Some rocky shores are flat while others are steep. This results in a wide variety of organisms that come to make the rocky shores their home. Some of the organisms you might find in the subtidal zone include sea urchins, sea anemones, rock crab, sea stars, kelp, sea cucumbers and moss. In the intertidal zone you may find algae, mussels, worms, limpets, shore crabs and a host of snails. There are far less organisms found in the splash zone. They include lichens, algae, some snails and maybe a few limpets. The rocky shore is home to many sessile and slow-moving invertbrtes and algae. Bathed in plankton-rich water, it enhances the delivery of particulate food to filter feeders.

This ecosystem is one that is named for the predominant organism. Mangroves are the largest flowering plants found in a marine environment. Mangrove trees have special adaptations which allow them to use seawater as a source of hydration and prop root which allow it to remain stable despite the soft bud. Mangrove communities are typically found in the coastal lagoons off the coast of Florida.

Day 102.2

A plethora of organisms live amongst the mangrove roots. Sea squirts, sponges, sea anemones, nurse sharks,  jelly fish, sting rays, spiny lobsters and fish choose this habitat for protection and nutrition.

 

The fouling community is the only marine community that is dependent upon humans. After a certain period of time, nearly any man made object that sits in the ocean will become the location of a fouling community. Shortly after the object is placed in the ocean, several bacteria, blue-green algae and protozoa build a film over the object. This film attracts the larvae of other fouling organisms and the community begins. Before long the object is covered in tunicates, barnacles, sea anemones, worms, sponges, bryozoan, isopods and hydroids.

This process usually occurs on dock, piers, and even boats!

kelp forest or kelp bed is a cold water marine habitat. Brown algae, commonly known as kelp can grow to lengths of at least 100 feet. They anchor themselves to the rocks and keep afloat by air bladders at the base of each blade or leaf thus forming a dense overhead canopy.

Giant kelp which grows off the coast of California is home to sea otters, sea lions, rock fish, sheepshead fish, sea urchins, palm kelp, sea bats, anemones, and sea stars.

(source)