Transcript Coastal Zones

Coastal Zones
Essential Questions
• What are Coastal zones?
• What are the types of coastal zones?
• What are the characteristics of local
coastal zones?
Waves, Beaches and Coasts
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• 30 mins
What are Coastal zones?
The Coastal Zone
What is a Coastal Zone?
• Also called a littoral zone
• Is part of a sea, lake, or river that is close
to the shore
• Extends from the high water mark to
shoreline areas that are permanently
submerged
Types of tides
• Neap Tide
– a less than average tide occurring at the first
and third quarters of the moon
• Spring Tide
– tides with the greatest range between highs
and lows, usually occurring during the full or
new moons
What are the types of coastal
zones?
Types of Coastal Zones
• Supratidal aka supralittoral zone
• Intertidal aka eulittoral zone
• Subtidal aka sublittoral zone
• Continental shelf
• Continental margin
Supratidal zone
• also called the splash, spray, or
supralittoral zone
• the area above the spring high tide line
that is regularly splashed, but not
submerged by ocean water
Organisms of the Supratidal zone
• patches of dark lichens can appear as
crusts on rocks in the upper supratidal
zone
• some types of periwinkles, Neritidae and
detritus feeding Isopoda commonly inhabit
the lower supratidal
Intertidal zone
• also called the midlittoral or eulittoral zone
• is the area that is exposed to the air at low tide and
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underwater at high tide
can be clearly separated into the following subzones:
– high tide zone, middle tide zone, and low tide zone
• can include many different types of habitats
– steep rocky cliffs, sandy beaches, or wetlands
• water is available regularly with the tides but varies from
fresh with rain, to highly saline, and dry salt with drying
between tidal inundations
Types of Intertidal zones
• Rocky intertidal communities
– occur on rocky shores, such as headlands,
cobble beaches, or human-made jetties
– tend to have higher wave action
• Soft-sediment habitats include
– sandy beaches, and intertidal wetlands (e.g.,
mudflats, and salt marshes)
– are generally protected from large waves but
tend to have more variable salinity levels
Organisms of the Intertidal zone
• plankton
• filter feeders—
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mussels, clams,
barnacles, sea squirts,
and polychaete
worms
Sea stars
scavengers – crabs
and sand fleas
• autotrophs ranging
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from microscopic
algae, to huge kelps
and other seaweeds
limpets and kelp
crabs
Goliath Grouper
sharks
Subtidal zone
• also called the Coastal Ocean, Neritic or
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sublittoral zone
extending from the low tide mark to the edge of
the continental shelf
has generally well-oxygenated water, low water
pressure, and relatively stable temperature and
salinity levels
areas where sunlight reaches the ocean floor,
that is, where the water is never so deep as to
take it out of the photic zone
Types of Subtidal zones
• The sublittoral zone is further divided into
2 regions:
– The infralittoral zone
• extends to five metres below the low water mark
• the algal dominated zone
– The circalittoral zone
• the region beyond the infralittoral
• dominated by sessile animals such as oysters.
Organisms of the Subtidal zone
• Corals are more common in the subtidal
zone
• Zooplankton live in this zone and together
with the phytoplankton form the base of
the food pyramid that supports most of
the world's great fishing areas
Continental shelf
• is the extended perimeter of each
continent and associated coastal plain
• the stretch of the seabed adjacent to the
shores of a particular country to which it
belongs
– known as Territorial waters
• abruptly terminates with the continental
slope
Continental Margin
• between the continental shelf and the
abyssal plain
• comprises a steep continental slope
followed by the flatter continental rise
• margins constitute about 28% of the
oceanic area
Continental Slope and Rise
• Continental slope
– usually begins at 430
feet depth and can be
up to 20 km wide
– connects the continental
shelf and the oceanic
crust
– the average angle is 3°,
but it can be as low as
1° or as high as 10°
• Continental rise
– found between the
continental slope and the
abyssal plain
– an underwater hill
composed of tons of
accumulated sediments
Over the Edge
The Endless Voyage Series
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What are the characteristics of local
coastal zones?
The Continental Shelf of NS
• The continental shelf extends from 125-230 km
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offshore to depths of about 200 metres.
Major offshore areas that make up the shelf are
the Northumberland Strait, southeastern Gulf of
St. Lawrence, Sydney Bight, Scotian Shelf,
Georges Bank, Gulf of Maine, and Bay of Fundy.
Features include basins up to 280 m deep on the
central shelf; fishing banks; channels; and Sable
Island, on Sable Island Bank, extending 26 m
above sea level.
The divisions in NS
• Four major geological or bedrock units are represented:
– (1) the Acadian Basin, an area of Triassic rocks in the Bay of
Fundy and northern Gulf of Maine,
– (2) terrestrial bedrock extending to 25 km off-shore along the
Atlantic coast of Nova Scotia and into basins on the south side of
the Gulf of Maine,
– (3) an outer area comprising the Middle and Outer Scotian Shelf,
consisting of Jurrasic, Cretaceous, and Tertiary rocks and
including Georges Bank, the outer Gulf of Maine, and the outer
part of the Laurentian Channel,
– (4) Sydney Basin, an area of carboniferous rocks northeast of
Cape Breton Island
Plant Life
• Beds of kelp and other marine algae grow
on the seabed close to shore
• microscopic phytoplankton occur both
nearshore and in most other waters
• There are 2 types of attached plants:
– those attached to rocks
• kelps and rockweeds but more than 300 species of
seaweed occur around Nova Scotia coasts
– those in soft bottom
• Eelgrass
Animals
• grazing vertebrates, invertebrates and suspension
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feeders such as mussels, scallops and oysters
grazers such as sea urchins
groundfish – cod, haddock, pollock, halibut, and various
species of flatfish
herring, mackerel, Bluefin Tuna, capelin, and some
smaller species
Seabirds – Herring and Black Back gulls, Great and
Double-crested cormorants
oceangoing birds – shearwaters, terns, jaegers,
phalaropes, and Storm-petrels
Nesting colonies of gannets, puffins, petrels, and
kittiwakes
Other Features of Coastal Zones
• Sand dunes
• Estuaries
• Littoral drift
– the process by which sediment is continuously moved
along beaches by wave action
– occurs because waves hit the shore at an angle, pick
up sediment (sand) on the shore and carry it down
the beach at an angle
– helps create many landforms including barriers, bay
beaches and spits