Marine and Coastal Ecosystems: Zones, Features, and Processes

Geo

Earth

Morphology

A branch of biology that deals with the form and structure

Pelagic Zone

Water itself (Only 2% of marine species live in the pelagic environment)

Benthic Zone

Ocean Bottom

Neritic Zone

Water extending from shoreline to continental shelf (200m)

Oceanic Zone

Water expanding from the continental shelf to the next

Epipelagic Zone

"Sunlight Zone" Surface - 200m (most pelagic fishes)

Mesopelagic Zone

"Twilight Zone" 200 - 1000m (bioluminescent organisms)

Bathypelagic Zone

"Midnight Zone" 1000 - 3000m

Abyssopelagic Zone

3000 - 6000m

Hadopelagic Zone

Greater than 6000m

Euphotic Zone

Surface - 200m

Disphotic Zone

200 - 1000m ('Twilight Zone'; 95% sunlight absorbed)

Aphotic Zone

1000m onward (No sunlight at all)

Splash Zone

Dunes to high tide line

Intertidal Zone

High tide and low tide line

Subtidal Zone

Low tide to continental edge (200m)

Bathyal Zone

Area of continental slope

Abyssal Zone

Plains and hills (80% of benthic)

Hadal Zone

Deep trenches

Sediment

Material that composes beaches

Shore

A zone that lies between the lowest tide level and the highest elevation on land affected by storm waves

Backshore

High-tide area of the beach

Foreshore

Low-tide area of the beach

Coast

Extends inland as far as ocean-related features can be found

Coastline

Marks the boundary between the shore and coast

Wave-cut Bench

A flat, wave-eroded surface

Berm

Dry, gently sloping region, sand

Beach face

Wet, sloping surface known as a low-tide terrace

Swash

The movement of water breaking

Backwash

Most of the water drains away from the shore

Longshore Drift

Moves sand parallel to the shoreline

Rip Currents

Flow away from shore and carry sediments offshore

Barrier Islands

-Extremely long offshore deposits of sand lying parallel to the coast.

-Formed by beach starvation or replenishment

Groins

Structures that trap sand moving along the coast

Jetties

Built in pairs to protect harbor entrances from waves

Breakwater

Placed offshore to dissipate the energy of incoming waves

Seawalls

Reflect and absorb wave energy during major storms

Bulkheads

Protect during minor storms, constructed of concrete

Beach Replenishment

Adding sand to the beach to replace lost sediment

Flood Proofing

Structural methods to ensure buildings are less susceptible to flood damage

storm profile

Stormy Weather = Erosion of sand and beach shrinks.

Narrow berm, flat beach face, and sand moved seaward to form longshore bars.

Grain size of sand increases b/c finer sand is transported offshore.

Happens over a short time span (hours/days).

Stormy, high-energy waves of water.

swell profile

Fair Weather = Accumulation of sand and beach grows.

Broad berm and steep beach face.

Happens over a long time span (weeks to months).

Calm, low-energy waves of summer.

longshore current

Breaking waves at an angle result in zigzag movement.

longshore drift

Zigzag movement of sediment caused by longshore current.

Barrier Islands formation theories

beach starvation and replenishment

beach starvation

Interruption of sand supply.

3 theories of barrier island formation

1.Waves transport sand landward until a sandbar is formed. Waves break over the top of the bar until a fully developed sea level sandbar emerges.

2.Elongate sand spits connected to the mainland become isolated in violent storms.

3. Dunes in low-lying coastlines become barrier islands with rising sea level.

Barrier Islands consist of:

ocean beach, dunes,barrier flat, high salt marsh, low salt marsh, lagoons

ocean beach

A typical beach environment. Summer/gentle waves: Beach widens, becomes steeper. Winter/High-energy waves: Narrow, sloping beach.

Dunes

Winds blow sand inward to produce coastal dunes. The lagoon's primary protection.

Barrier Flat

Behind dunes. Forms as a result of the deposition of sand driven through passes during storms. Colonized by grass.

High Salt Marsh

Extends to the highest spring tide line.

Low Salt Marsh

Extends from about the mean sea level to the high neap-tide line. Unvegetated.

Lagoons

Shallow, protected water bodies that form between the mainland and the barrier islands.

Peat Deposits

Remnants of old marshes that lie beneath the barrier islands.