LEC 17 - INTERTIDAL ZONE II (ZONATION)

Question 1

what are the physical and biological features that intertidal animals must contend? (2 and 3, respectively)

Answer 1

physical:
- heat, causing desiccation
- wave shock, causing abrasions or dislodging u

biological:
- limited feeding time
- limited breathing time
- competition/predation

Question 2

how have some animals adapted to heat stress?

Answer 2

• reduction of surface area/volume ratio (circular shape) - less area for water to evaporate off
• evaporative cooling: letting out a little water to cool u down (like sweating)
• close urself off SUPER tight so no water can escape
• cover urself in sand

Question 3

what can damage can wave shock do?

Answer 3

damage from wave crashing on u, abrasion from suspended particles, can dislodge u from ur spot

Question 4

considering the limited availability of feeding times, what are the implications for intertidal energy budgets?

Answer 4

• sessile organisms grow slower
• motile organisms move stay lower in the tide pool where they are more likely to stay submerged

Question 5

considering the limited time frame of gas exch, what are the implications for intertidal organisms?

Answer 5

• most animals reduce their metabolic rate when the tide is down
• some animals can respire air if it is moist enough

Question 6

what did cornell’s field experiments discover about vertical zonation?

Answer 6

cornell’s experiments began with 4 observations:
1. barnacle Chthamalus (CH) was highest on shore
2. barnacle Semibalanus (SE) was found below CH
3. in low water, barnacles were rare
4. mobile snail predator Nucella (NU) was common in low water

first, he took rocks w CH and moved them down into SE territory, and found them to get outcompeted

then, he took SE, put them in a cage, and moved them into NU territory, where they were found to be okay (when predation was removed, everything was good)

the implications were the biological factors rule lower zonation, while physical factors rule higher zonation

Question 7

what is a keystone species? who did Paine observe and assign this label to?

Answer 7

keystone species: a really important species whose presence affects the community makeup

noted that when Pisaster ochraceus was removed, Mytilus califoranus became dominant over the entire ecosystem

ie Pisaster is keystone bc it keeps Mytilus in check

Question 8

how can small scale and large scale disturbances vary?

Answer 8

small scale disturbances can be recuperated pretty easily, but large scale disturbances can be colonized by foreign organisms, sometimes resulting in permanent settlements

Question 9

define recruitment. why might superior species not completely dominate an area? what might prevent larval recruitment?

Answer 9

recruitment is the aging of larvae into mature, reproducing adults

a superior species may not completely dominate an area due to low recruitment rates.

such factors of low recruitment include
- less food avail
- water temp changing (el nino years)
- bad currents (less mixing = less plankton)
- salinity conditions changing due to rain