1. Coastal Marine Communities
- Substrates and Adaptations: Rocky Intertidal Zones and Beaches
- Kelp Forests
Reading:
4th Ed: Ch 16 Sec 10, 12-13
5th Ed: Ch 16 Sec 10-12
Graphic: Kelp forest, S. Fisher courtesy of National Marine Sanctuaries and NOAA.
2. Upwelling and Nutrients
Wind blowing along the coast moves water toward or away from the coast
This water is "replaced" by water that moves vertically
Northern hemisphere:
- Winds from the north drive offshore currents
- "upwelling" brings nutrient-rich water up from below ("upwelling") promoting
high productivity
Graphic: Garrison, 4th Ed., Fig. 9.15a, pg 221, 5th Ed., Fig. 9.16a, pg 213.
3. Primary Productivity
High primary productivity near coasts, due to good availability of nutrients,
provides a strong base for many coastal food webs
Graphic: Image provided by the SeaWiFS project, NASA/Goddard Space Flight Center
and Orbimage, see Garrison, Fig. 14.6, pg 353.
4. Intermediate Disturbance Hypothesis
Maximum species diversity often occurs at intermediate levels of disturbance
High disturbance
- very unstable communities
- disturbance-tolerant species dominate
Low disturbance
- exclusion of less competitive species
- dominance by a single or a few species
Intermediate disturbance
- moderate disturbance stress and competition
Graphic: (top) Rocky intertidal zone, courtesy of NOAA, (bottom) Brittle stars
in the deep sea off Cape Hatteras. S. Stancyk, photographer. Courtesy of NOAA
NURP and Univ. of S.Carolina.
5. Rocky Intertidal Communities
Intertidal = band below high and low tides
- high energy environment
- rapid changes in temperature, moisture, salinity
- many different habitats
- abundant food
Graphic: (Top) Rocky intertidal zone. Olympic National Marine Sanctuary
Collection. (Bottom) Painted Urticina anemone. Both Courtesy of NOAA.
6. Tide Pools
Tide pools provide refuge from dessication, but experience rapid changes of
temperature, salinity and oxygen
Organisms must tolerate rapid changes in their physical environment
Graphic: Tide pools on the Olympic Coast of Washington State, photo by N.Sefton,
courtesy of National Marine Sanctuaries, NOAA.
7. Sand Beach and Cobble Beach Communities
Sand and cobble beaches are hostile environments
Difficulties:
- loose and abrasive material
- temperature changes
- wave shock
- exposure
Conditions favor larger animals
Graphic (top) Female blue crab on the beach. Photograph by M. Hollinger, NODC
Biologist, courtesy of NOAA, (bottom) Cobble beach, courtesy of NOAA.
8. Poke Your Toes in the Sand and Mud...
In sand and mud, living subsurface provides protection and access to food
Large organisms can live below the surface
Microscopic organisms live between the sand and mud grains
Graphics: (top) worm tubes in the sandy bottom, courtesy of OAR/National
Undersea Research Program, (bottom) Garrison, Fig. 16.9c,d.
9. Below wave base, communities thrive
On cobble bottoms, one successful approach is to live below wave base in calmer
water
Scallops and sponges thrive on cobble bottoms off the Maine Coast
Note thick plankton which serves as food for filter feeders
Graphic: Courtesy of NOAA.
10. Kelp Forests - Biologically Rich Coastal Communities
- Cold water
- High productivity
- Shallow (2-30 m depth)
Kelp provides shelter and food and supports diverse communities
Graphics: Garrison, Fig.s 14.21b, 14.22, pgs 369-370.
11. Seaweed Communities
Herbivores - feed directly on seaweed (snails, limpets, small fish)
Carnivores - feed on animals that in habit the kelp forest
Detritivores - feed on dead matter that has sunk to the bottom
Graphic: (top) Fishing in a southern California kelp forest, B.Chrisney,
photographer, courtesy of NOAA. (bottom) Giant kelp, an important fish habitat
can grow up to 2 feet per day. Courtesy of NOAA Restoration Center.
12. The Kelp Canopy
Giant kelp prefer calm waters
Bull kelp dominates in higher energy environments
Where the two ranges overlap, Giant Kelp out competes Bull kelp for light
Graphics: Top Giant Kelp. Bottom, Bull (Whip) Kelp. Courtesy of NOAA.
13. Canopy Assemblage
Canopy dwellers live on the seaweed
Members of this community
- small crustaceans
- worms
Opportunities and challenges
- plenty of food
- plenty of predators
Graphic: (top) Kelp community, courtesy of National Undersea Research Program,
(bottom) Close up of giant kelp, S.Anderson, photographer, courtesy of National
Marine Sanctuaries, NOAA.
14. Planktonic Assemblage
Lives suspended in the water column
Members of this community include juvenile fish, crustaceans, jellyfish
Opportunities and challenges:
- canopy provides protection from predators (seabirds, sharks)
- intense predation and competition for resources
Graphic: (top) Garibaldi, a fish the frequently inhabits kelp forests, K.Evans,
photogrpaher, courtesy of National Marine Sanctuaries, NOAA.
15. Midwater and Bottom Fish
Distinct habitats within the kelp forest house specific species of fish
The small Seņorita fish finds both cover and food in the kelp canopy
Many bottom fish are important game fish and important predators within the
ecosystem
Graphic: Black rockfish in a kelp bed. Photograph by Kip Evans. Monterey Bay
Naional Marine Sanctuary Colllection. Courtesy of NOAA.
16. The Macrophyte (Seaweed) Understory
The understory contains brown and red algae that tolerate low light levels
In winter:
- kelp canopy can be removed by storm waves
- understory responds to higher light levels with more growth
Graphic: Sunlight filters through the dense kelp canopy allowing growth of the
understory. K.Evans, photographer, courtesy of NOAA National Marine Sanctuaries.
17. Bottom dwellers
Members of this community
- crustaceans
- echinoderms
- sponges
- anemones
Seasonal disturbances present opportunities and challenges
Graphic: (top) Benthic invertebrate community, (bottom) urchins and sea stars.
Both: N.Sefton, photographer, courtesy of National Marine Sanctuaries, NOAA.
18. The Marine Mammals
Kelp forests are home to sea otters and feeding grounds for sea lions, seals and
whales
Otters are keystone predators - they feed so extensively on crabs, urchins,
clams that they control the abundance of these organisms
Graphic: (top) Alaskan fur seal, (bottom) sea otter, J.Bortniak, photographer,
both courtesy of NOAA.
19. Kelp, Urchins, Otters
Urchins feed voraciously on kelp
- Can deforest an area within weeks if their numbers are not controlled
- Otters control urchins by predation
- Otters were hunted for their pelts along the west coast; kelp forests (and
some fisheries) declined
- Otters are now protected and kelp forests are recovering
Graphics: (top) Otter, K.Evans, photographer, (bottom) purple urchin, L.Francis,
photographer, both courtesy of NOAA National Marine Sanctuaries.
20. Preview of Next Lecture
Nature’s Gardens - Coral Reefs
Reading:
4th Ed: Ch 16 Sec 15, 21-22, Ch 15 Sec 5, Ch 12 Sec 22-24
5th Ed: Ch 16 Sec 15, 21, Ch 15 Sec 5, Ch 12 Sec 21-23
Graphic: Coral Reef, courtesy of NOAA.