Lecture 19- Rocky Intertidal Corals and Whales

Question 1

vertical zonation

Answer 1

• hallmark of intertidal zone

- communities are divided into distinct bands or zones as characteristic heights

Question 2

how are species arranged?

Answer 2

species are not randomly distributed throughout the zone by arranged within narrow vertical vertical ranges

Question 3

how do the zones look like?

Answer 3

sharply divided belts easily distinguished by the colors of the assemblage (community) of organisms that live there

Question 4

physical stresses

Answer 4

often set the upper limit to species distributions

Question 5

physical stresses examples

Answer 5

• desiccation
• temperature
• food availability
• wave energy
• salinity
• dissolved oxygen

Question 6

biological interactions

Answer 6

• often set the lower limit to species distributions

Question 7

upper limit of grey and rock barnacles

Answer 7

determined by emersion, larvae that settle too high in the intertidal dry out and die (physical factor)

Question 8

little grey barnacles

Answer 8

can tolerate drying better than rock barnacles so they settle higher in the intertidal

Question 9

lower limit for rock barnacles

Answer 9

determined by competition from mussels and predation by whelks or sea stars (biological factors)

Question 10

biological factors

Answer 10

• competition for space: space on rock to attach is a valuable source that is in short supply
• predation

Question 11

general rule of zonation

Answer 11

• upper limit is usually determined by physical factors

- lower limit is determined by biological factors

Question 12

physical disturbance

Answer 12

• can regulate species diversity within a community
• examples: wave energy from storms and log damage
• can open up gaps or patches in the rocky intertidal

Question 13

intermediate disturbance hypothesis

Answer 13

disturbance maximizes species diversity by periodically removing competitively dominant species and allowing less competitive species to reestablish themselves

Question 14

too much disturbance

Answer 14

keeps the rock bare with few species

Question 15

too little disturbance

Answer 15

allows the dominant competitor for space to take over and form a monoculture (single species)

Question 16

starfish predation

Answer 16

• produces high intertidal community diversity
• Sets lower limits of mussel distributions in rocky intertidal
• Leads to higher species diversity within a rocky intertidal community

Question 17

mussels

Answer 17

out compete most of the other intertidal organisms for valuable space

Question 18

pisaster (starfish) predation

Answer 18

• sets the lower distributional limit to mussels and below this distributional limit other species can settle in
• its removal allow mussels to take over

Question 19

keystone species

Answer 19

• species that have effects on their communities that are proportionally much greater than their abundance would suggest
• example is pisaster

Question 20

sea otters and sea urchins

Answer 20

• sea otters eat sea urchins which eat tiny kelp before they grow large
• removal of sea otters allow increase of sea urchins and decrease in kelp

Question 21

coral anatomy

Answer 21

• calcium carbonate support structure

- process of building calcium carbonate reef structure is very slow: <1 mm per year to about 20 mm per year

Question 22

Zoozanthellae

Answer 22

• chlorophyll-containing algal symbionts that live in the coral polyp
• give corals their colors

Question 23

corals receive — of their overall nutrition from photosynthetic-derived products

Answer 23

60-90%

Question 24

Limits to Coral Growth

Answer 24

• temperature
• sunlight
• space to grow
• predation

Question 25

temperature and corals

Answer 25

• Limits most coral growth to tropical latitudes
• Optimal: 26-28 C
• Restricted: 18-36C
• Boundary for 20C isotherm: most corals live within this boundary

Question 26

sunlight and corals

Answer 26

• Limits coral growth to a depth range extending from the ocean surface down to maximum of about 25 meters
• Light required for zooxanthellae to photosynthesize

Question 27

drowned reefs

Answer 27

dead reefs that occur when the island sinks too fast or sea level rises too fast and the reef cannot keep up with its upward growth because it becomes too submerged in deep/dark waters

Question 28

the competitive advantage for taking over space is shifted in favor of macroalgae when

Answer 28

nutrients from agricultural activities run off the coast and onto coral reefs

Question 29

crown of thorns starfish (acanthaster)

Answer 29

• important predator of corals

- eutrophic conditions increase phytoplankton which increases growth of acanthaster

Question 30

— of the Great Barrier reef has been bleached since 2016

Answer 30

half

Question 31

increases in CO2 in atmosphere leads to

Answer 31

• increase in ocean acidity
• above 490 ppm enhances coral loss, we are at 406 ppm and it increases 2ppm to 3 ppm each year so we will reach 450 in 20 years

Question 32

pre-industrial atmospheric CO2

Answer 32

550 ppm

Question 33

1.5 C world

Answer 33

Coral reefs will decline by 70-90%

Question 34

2C World

Answer 34

virtually all (>99%) coral reefs will be lost