Types of Coastal Zones
The five types of coastal zones we have studied in class include: estuaries, rocky shore, sandy beaches, salt marshes and mudflats. The following are summary notes made from the “By the Sea” booklets we have used in class.
Estuaries
· An estuary is a body of water partially surrounded by land, where fresh water from a river mixes with ocean water.
· Three factors determine the characteristic of an estuary: the shape of the estuary, the volume of river flow at the head of the estuary and the range of tides at the estuary’s mouth.
· Generally, due to the Coriolis effect, fresh river water flows out on the right side of the river and the incoming tidal ocean water flows in on the left side.
· Salt conditions fluctuate constantly due to the mixing of fresh and salt water.
· Diversity of plants and animals is quite high. This is due to favourable temperatures, constant replenishment of nutrients and shallower waters. Movement of nutrients around an estuary occurs as the tide comes in and goes out. Tides also cause nutrients in the sediments to come up to the surface (upwelling).
· Phytoplankton, bacteria and fungi support the base of the food web in an estuary. Plant species are dominated by eelgrass. Animals include marine worms, clams and other shellfish, crabs, lobsters, fish, reptiles, birds and marine mammals.
· Important for the local economy because of commercial fishing, aquaculture and recreational fishing.
· During colonization, humans tended to settle around estuaries. This means humans have had major negative impacts on these areas.
Rocky Shore
· Rocky shorelines are coastal areas dominated by bedrock, boulders and cobbles. They are high-energy coastal environments where sand does not stay in one place for very long.
· Wind, ice, temperature, waves, currents, tides, salt and sediments cause this area to be ever-changing.
· The constant coming and going of the tides causes the formation of distinct zones in the rocky shore area. The upper intertidal zone is dry for the longest period of time while the lower intertidal zone is dry for the shortest period of time. The different zones have different organisms that can tolerate the conditions. The greatest diversity of life is found in the lower zone.
· Much of the plant life associated with rocky shores is seaweed. Animals include various species of periwinkles, dog whelks, mussels, oysters, clams, chitons, limpets, sea slugs, barnacles, crabs, sand shrimp, amphipods and various species of starfish.
Sandy Beach
· Sandy beaches are more than sand and sun. These sections of the shoreline are covered by fine to coarse sediments, gravel and rocks.
· Wind and waves determine their shape. They are very dynamic areas (change often). Winds and wave action make it very difficult for plants and other producers to establish a population.
· Beaches are built in the summer and eroded in the winter. Currents on the beach erode and rebuild the beach.
· Diversity of plants and animals is quite low. For plants, only salt tolerant plants and some types of microscopic algae are found on beaches. For animals burying worms and mollusks (mainly clams) dominate the shoreline while crustaceans (like sand shrimp), amphipods (like sand fleas), sand dollars and jellyfish can be found in the shallow waters. Marine birds (like gulls and piping plovers) frequent the upper shore areas
Salt Marshes
· Smelly, grassy, wastelands of channels and mud found near estuaries and beaches.
· Very productive ecosystems. The main source of the nutrients in this area comes from the decay of marsh grass species which are deposited and delivered to other parts of the coastal systems by the movement of water in and out of the marsh.
· The four main functions of salt marshes are: to provide shelter for plants and animals, trap nutrient-rich sediment, are important as nurseries for many fish and serve as feeding and nesting areas for many species.
· Usually extend out to mudflats.
· Cord grass species dominate this area but other plant species include rushes, sea lavender, glasswort, sedge and arrow-grass. Animals in this area include: ribbed mussels, dog whelks, crabs, worms and numerous minnows and juvenile fish species. Birds are also abundant.
· Salt marsh food webs are complex due to the abundance of decomposers (bacteria and fungi) that supply nutrients to the filter feeders.
Mudflats
· Formed by sloping shores and sediment deposition. Sediments originate from the erosion of adjacent shorelines and estuaries that empty into the bays. The sediments are composed silt, clay and fine sands.
· Often the starting point for salt marshes.
· Currents change the shape and appearance of mudflats regularly, while ice can have a dramatic effect seasonally.
· Salt conditions vary due to evaporation of water in the summer. This means the area has a higher concentration of salt in the summer and less salty after rain or runoff from adjacent estuaries.
· The diversity of organisms is low compared to other types of coastal areas. Plants are few, but some are found in the upper areas of the region where the salt marsh starts. Some protists (like diatoms and dinoflagellates) and microalgae are found in this area. Invertebrates found on mudflats include clam species. mussels, dog whelks, moon snails, mud shrimp and burrowing worms. Birds (like sandpipers and piping plovers) are common visitors to mudflats to feed.
· Survival for many species is ensured through the production of large numbers off offspring, many of which never reach adulthood due to predation.
Characteristics of Coastal Zones
Estuary:
Characteristics / DetailsDescription / · An estuary is a body of water partially surrounded by land, where fresh water from a river mixes with ocean water.
Challenges faced by the organisms in the area / · Salt conditions fluctuate constantly due to the mixing of fresh and salt water.
· Maintaining a favourable living location can be difficult.
Productivity / · High due to favourable temperatures, constant replenishment of nutrients and shallower waters.
Wildlife / · Phytoplankton, bacteria and fungi support the base of the food web in an estuary.
· Plant species are dominated by eelgrass.
· Animals include marine worms, clams and other shellfish, crabs, lobsters, fish, reptiles, birds and marine mammals.
Human Activities /
· Important for the local economy because of commercial fishing, aquaculture and recreational fishing.
· PollutionRocky Shore
Characteristics / DetailsDescription / · Rocky shorelines are coastal areas dominated by bedrock, boulders and cobbles.
Challenges faced by the organisms in the area / · Wind, ice, temperature, waves, currents, tides, salt and sediments cause this area to be ever-changing and difficult for some species.
Productivity / · The different tidal zones have different organisms that can tolerate the environmental conditions. The greatest diversity of life is found in the lower zone.
Wildlife / · Much of the plant life associated with rocky shores is seaweed.
· Animals include various species of periwinkles, dog whelks, mussels, oysters, clams, chitons, limpets, sea slugs, barnacles, crabs, sand shrimp, amphipods and various species of starfish.
Human Activities / · Low due to the fact that rocky shores can be difficult to access
Sandy Beach
Characteristics / DetailsDescription / · Sections of the shoreline that are covered by fine to coarse sediments, gravel and rocks.
Challenges faced by the organisms in the area / · Wind and waves. These factors make it very difficult for plants and other producers to establish a population.
Productivity / · Diversity of plants and animals is quite low.
Wildlife / · Only salt tolerant plants and some types of microscopic algae are found on beaches.
· Animals include burying worms and mollusks (mainly clams) dominate the shoreline while crustaceans (like sand shrimp), amphipods (like sand fleas), sand dollars and jellyfish can be found in the shallow waters. Marine birds (like gulls and piping plovers) frequent the upper shore areas
Human Activities / · Tourism
Salt Marsh
Description / · Smelly, grassy, wastelands of channels and mud found near estuaries and beaches.
· Usually extend out to mudflats.
Challenges faced by the organisms in the area / · Salt conditions vary due to evaporation of water in the summer. This means the area has a higher concentration of salt in the summer and less salty after rain or runoff from adjacent estuaries.
Productivity / · Very productive ecosystems. The main source of the nutrients in this area comes from the decay of marsh grass species.
· Salt marsh food webs are complex due to the abundance of decomposers (bacteria and fungi) that supply nutrients to the filter feeders.
Wildlife / · Cord grass species dominate this area but other plant species include rushes, sea lavender, glasswort, sedge and arrow-grass.
· Animals in this area include: ribbed mussels, dog whelks, crabs, worms and numerous minnows and juvenile fish species. Birds are also abundant.
Human Activities / · Bird watching
Mudflat
Characteristics / DetailsDescription / · Sloping shores composed silt, clay and fine sands.
· Often the starting point for salt marshes.
Challenges faced by the organisms in the area / · Currents change the shape and appearance of mudflats regularly
· Salt conditions vary due to evaporation of water in the summer. This means the area has a higher concentration of salt in the summer and less salty after rain or runoff from adjacent estuaries.
Productivity / · Low
Wildlife / · Plants are few, but some are found in the upper areas of the region where the salt marsh starts.
· Some protists (like diatoms and dinoflagellates) and microalgae are found in this area.
· Animals include invertebrates found on mudflats include clam species. mussels, dog whelks, moon snails, mud shrimp and burrowing worms. Birds (like sandpipers and piping plovers) are common visitors to mudflats to feed.
Human Activities / · Clam digging
Characteristics of Coastal Zones
Estuary:
Characteristics / DetailsDescription
Challenges faced by the organisms in the area
Productivity
Wildlife
Human Activities
Rocky Shore
Characteristics / DetailsDescription
Challenges faced by the organisms in the area
Productivity
Wildlife
Human Activities
Sandy Beach
Characteristics / DetailsDescription
Challenges faced by the organisms in the area
Productivity
Wildlife
Human Activities
Salt Marsh
Description
Challenges faced by the organisms in the area
Productivity
Wildlife
Human Activities
Mudflat
Characteristics / DetailsDescription
Challenges faced by the organisms in the area
Productivity
Wildlife
Human Activities