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Coastal Seas  A Coastal Sea is the part of the world ocean that covers the continental shelf.  Continental shelves extend variable distances from continents.

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Presentation on theme: "Coastal Seas  A Coastal Sea is the part of the world ocean that covers the continental shelf.  Continental shelves extend variable distances from continents."— Presentation transcript:

1 Coastal Seas  A Coastal Sea is the part of the world ocean that covers the continental shelf.  Continental shelves extend variable distances from continents and typically gradually descend to 140 m (460ft) before dropping off as the continental slope.

2 Continental Shelves

3 Coastal Sea

4 Light Penetration  Epipelagic / Euphotic Zone = The zone of the oceans to 200 m with enough light to sustain photosynthesis.  Almost all of all continental shelves is within the euphotic zone.  However, almost all photosynthesis occurs in the top 30 m and turbidity can reduce that.  The benthic zone of continental shelves away from shore is still pretty dark and rarely supports any but the most minimal photosynthesis.

5 Tides  Tides = Periodic movement of the sea due to the gravitational effects of the sun and the moon on the world ocean (High and low tides ~ twice a day.)  Spring Tides – are tides with the largest tidal range (greatest range of tides = every 14 days)  Neap Tides – are tides with the lowest tidal range (least range of tides = every 14 days)

6 Tides

7 Tidal Range

8 Coastal Sea: “The Littoral”  Littoral zone = ? (Different for lakes.) -area affected by the ocean to ~ 60 m deep -splash zone to deepest area affected by wave energy -covered and uncovered by tides (Eulittoral)  Surf zone = area above where wave energy affects the bottom and waves begin to break.

9 The “Littoral” Substrate  Hard substate = rock outcrops, large boulders, and/or rocks not moved by wave or tidal action. = VERY small part of littoral  “Soft” substate = particles (from microscopic silt to rocks) moved by wave or tidal action. = most of the littoral -mud, sand, gravel (beaches & mud flats) -well sorted = particles mostly same size (particles move easily) -poorly sorted = particles vary in size (particles move less easily)

10 Coastal Sea: Neritic Zone  Neritic zone = from the lowest level NOT uncovered by the tides to the edge of the continental shelf -Neritic pelagic -Neritic benthic – continental shelf sea floor

11 The Neritic Substrate  Almost all of the substrate of the neritic zone is soft due to sediment from the water column and little or no wave action effects.

12 Stream/Runoff Contributions

13 Coastal Upwelling

14 Oceanic Primary Production

15 Coastal Primary Production  Macrophytes = near shore; green, brown, and red algae In general, surface to deeper brown-to-green-to-red (This is very rough and all are found shallowly and deeply.)  Periphyton = near shore; mostly green algae, diatoms, and cyanobacteria  Phytoplankton = euphotic zone; mostly green algae, diatoms, dinoflagellates, cocclithophores, and cyanobacteria

16 “Littoral” Zone Food Web periphyton & macrophytes grazers fishes, mollusks, crustaceans “predatory” fishes, mollusks, crustaceans, echinoderms planktivores fishes, mollusks, crustaceans, echinoderms, cnidarians phytoplankton & zooplankton (mostly “washed in”) deposit feeders (soft substrates) fishes, mollusks, crustaceans, echinoderms particulate organic matter (POM) (from a range of sources) bacteria

17 Euphotic Neritic Food Web grazing zooplankton predatory zooplankton bacteria phytoplankton phytobacteria dissolved organic compounds (DOC) “predatory” fishes, mollusks, etc. phyto- plankti- vorous fishes microzooplankton larger “predatory” fishes, mammals, etc.

18 Neritic Benthic Food Web predatory animals (echinoderms, mollusks, crustaceans, fishes, etc.) bacteria dissolved organic compounds (DOC) particulate organic matter (POM) collecting/scavenging animals (annelid worms, echinoderms, mollusks crustaceans, fishes, etc.) larger predatory animals (mollusks, crustaceans, fishes, etc.)

19 Soft Substrate Communities  Affected by constant change in substrate due to wave action or sedimentation.  Species composition usually more structured by disturbance and predation (less affected by competition)

20 Reefs & Banks  Reef = a solid (hard) outcrop in shallow water reached by sunlight. (Not all are coral reefs. e.g., oyster reefs )  Bank = shallower regions of the offshore continental shelf.

21 Sea Grass Communities  Fully aquatic submerged plants (true grasses).  Require soft substrates. When present they stabilize the substrates. Primary production and species richness higeher.

22 Sea Grass Communities Seahorses Pipefish Lizard Fishes Sharptail Eel

23 Hard Substrate Communities  Less change in substrate and substrate provides fixed anchoring point.  Species composition usually structured by competition and predation (usually a little less affected by disturbance)

24 Hard Substrate Limitation  The predominance of soft bottoms means that hard substrates are limited.  Artificial reefs are rapidly colonized. Both biomass and species richness are greater around such reefs.

25 Rocky Intertidal Zonation  Provides a gradient of physical conditions.

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27 Tropical Coral Reefs  Coral reefs found only between 30º N and S latitude & require shallow, warm, clear water.  Built by coral animals with mutualistic algae – CaCO 3 skeletons.  The need for “shallow” waters means that most are around land.

28 Coral Polyps

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30 Reef Types

31 Fringing Reef flat back reef reef face

32 Australia Great Barrier Reef

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34 Tropical Coral Reef Communities  Primary production from microphytic algae in corals and macrophytic algae.  Plankton from open water important.  Very diverse communities.  Structured by competition, predation, & disturbance.  Competition (especially for space) is usually very intense. Many territorial animals.

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36 Bluehead Wrasse Parrot Fishes Cleaner Gobies Butterfly Fishes

37 Human Impacts: General  Pollutants from stream & direct runoff. -additional sediment -heavy metals & industrial pollutants -phosphate (P) [and nitrate (N)]  Over fishing/over harvest – removing part of the community.  Red Tides – blooms of certain species of dinoflagellate (phytoplankon) that can result in low oxygen and/or neurotoxin release.

38 Human Impacts: Sea Grasses  Pollutants from stream & direct runoff. -additional sediment – can cover or increase turbidity -heavy metals & industrial pollutants -phosphate (P) [and nitrate (N)] – overgrown by periphyton and smothered  Dredging (& dragging of boat anchors) – root damage takes a long time for recovery.

39 Human Impacts: Coral Reefs  Pollutants from stream & direct runoff. -additional sediment – can cover or increase turbidity and smother -heavy metals & industrial pollutants -phosphate (P) [and nitrate (N)] – overgrown by periphyton/macrophytes and smothered  Physical Damage to the Reef –takes a long time for recovery.  Increase or decrease in temperature.  Coral stress causes bleaching.

40 Human Impacts: Coral Reefs

41 Coral Bleaching

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45 Human Impacts: Fishing  Reefs -dynamite fishing -poisoning  Seagrass Beds -dynamite fishing -trawling – net drags  Soft bottom -trawling – net drags -bycatch dumping


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