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Where can we find hard bottom habitats?
Practically everywhere in the ocean. From coastlines to deep sea, from the equator to both of the poles.
What are hard bottom habitats?
Primary geological features of the ocean. Not influenced by biogeography.
Describe where the littoral zone is located
An area located between the supralittoral (high tide) and sublittoral (low tide) zones. Typically extends from the shoreline to the continental shelf.
Describe where the infralittoral zone is located
An area located between the sublittoral (low tide) and lower infralittoral zone. Typically extends beyond the continental shelf where light is still available for photosynthesis.
Define the infralittoral zone, what part of the intertidal system is it part of?
A shallow zone in the subtidal zone dominated by macroalgae extending as far as enough light is sufficient for photosynthesis
What would you typically find in the infralittoral zone?
String seaweeds, grazers, and kelp
Describe where the circalittoral zone is located
An area that can be found beyond the lower infralittoral zone. There is not enough light for photosynthesis to be possible.
Define the circalittoral zone, what part of the intertidal system is it part of?
A region below the infralittoral zone dominated by invertebrates (sessile and mobile). There is no macroalgae due to the lack of sunlight.
What would you typically find in the circalittoral zone?
filter feeders
Describe an important factor affecting hard bottom habitats on a small-scale community structure
Slope can affect hard bottom habitats on a small-scale community structure
Define slope (in terms of MSCI 340)
Slope is the angle of the substrate, which fundamentally determines the community structure of hard bottomed habitats
What are the three types of slope.
Identify whether each of these slope types is “macroalgae dominant“, “diverse”, and “epifaunal dominant”.
Flat - “macroalgae dominant”
Sloped - “diverse”
Vertical - “epifaunal dominant”
Describe an epifaunal organism
An organism that lives on the surface of the substrate
Describe an infaunal organism
An organism that lives in the substrate
What is the MAIN determinant of species composition at different slopes?
light availaibility
What are the other determinants of species composition at different slopes?
water flow, flow availability, water temperature
Describe the relationship between slope and light availability
As the slope changes, the light level changes
Describe an important factor affecting hard bottom habitats on a medium-scale community structure
Water supply can affect hard bottom habitats on a small-scale community structure
Why is water supply important for hard bottom habitats?
Water supply determines the density, salinity, available nutrients, and water flow in a given area.
What are the three variables that stratify the water layers?
Temperature, salinity, and density
Define a seamount
An inactive underwater volcano that extends from the seafloor to the water column.
How do seamounts interact with the water column
They create hard-bottomed habitats, coming into contact with the flow of water masses
What makes seamounts significant for marine ecology?
They are the only phenomenon on Earth where hard substrates interact with the water column without being part of the continental shelf.
Seamounts also facilitate connectivity between the mainland and the island
What’s a seamount that we have off the coast of Monterey
Davidson’s Seamount
How can humans influence the rocky bottoms?
Shipping containers can fall off cargo ships, creating artificial rocky bottoms. They also become an artificial form of connectivity between the mainland and islands.
Name the five abiotic disturbances at the rocky bottoms
temperature, storm surge, earthquake, swells, iceberg scours
How do the influences of abiotic disturbances decrease with water depth?
An example can be wave orbitals, which decrease with depth. This reflects the effectiveness of storm penetration to the sediment below.
What are two biotic disturbances at the rocky bottoms?
Predation and competition
Describe how predation varies with water depth
This disturbance varies a lot with depth. Consumer activity is more limited in shallow areas and the variation in predation risk changes with water movement
Describe how competition varies with water depth
This disturbance varies less with depth (not including light penetration). Space is a main resource for competition.
What is an example of competition with space in context of rocky bottom habitats?
Horizontal slopes will produce more competition for space, as different organisms compete for different attributes of the seafloor space
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