Rocky Shores Flashcards
What are the implication of tides on Rocky shore habitat
Twice a day this marine habitat is suddenly altered to conditions that are essentially terrestrial
Abiotic stress associated with emersion
Desiccation temp fluctuations salinity fluctuations oxygen levels wave exposure
Adaptations for desiccation
Possessing a shell helps with desiccations as the operculum can close trapping water eg Nucella lapillus. Some form air tight adhesions to the rock surface they grow shells custom to the Rock contour (home scar) eg patella vulgata
More adaptations to desiccation
Some organisms can retract their tentacles.
Mobile adaptations eg cancer pagurus seek out permanently wet environments when the tides are out. The exoskeleton is waterproof preventing waterloss however the joints leak so staying stationary is ideal.
Adaptations for temperature fluctuations
Water acts as a temperature buffer as it has a high latent heat capacity however air temperature fluctuate more quickly therefore mobile species will stay in water and juveniles are often restricted to the low shore as they are smaller. Larger animals maintain temp fluctuations easier.
Sessile organisms release water from the operculum on hot days to cool off, they cluster together to make a microclimate where it is cooler
Intertidal molluscs are more tolerant to freezes as they produce anti freeze in their cells
Adaptations for salinity fluctuations
As salt content changes it changes the water potential. When tides are out it could rain making water less saline make water move into marine organisms cells causing them to swell and rupture. On hot days water will evaporate causing it to be more saline cause img cells to shrink killing the organisms. Common is asterias Rubens hence why they are restricted to low shore
Coping with oxygen changes
Warm water is less able to hold oxygen. Patella vulgata hold a reservoir of water under the shell to avoid desiccation but also to have oxygen for respiration. When this oxygen is used up the limpet can lift up the shell to obtain more oxygen
How is wave action an abiotic stress
Damage caused by hydraulic action waves can also pull organisms out to see which they aren’t adapted too
How can wave action be beneficial
Replenish stagnat water to increase oxygen
Free up space for juveniles
Reduce predation from seabirds
Adaptations to wave action
Body form of Nucella lapillus is designed to roll out of wave to stop being carried out to see
Patella vulgata have hard durable shells
More delicate organisms live in mussle beds for protection or they are only found on sheltered shores
Fucus vesiculosus (bladder wrack) have air pockets to make it buoyant for more light for photosynthesis. The more wave crash the less bladders the seaweed will have to avoid being ripped off and taken to sea
What is competition like at different points on the shore
High shore communities are dominated by snails and limpets algae due to high abiotic stress as it’s further up the shore there is less competition
Low shore communities is dominated by kelp and red algae due to it being closer to the sea there is less abiotic stress therefore high competition
What are the limitations of zonation
No distinct zones of species as many overlap between zones however there are vertical limits of species where they can survive
What are the algae colour zones
Green,brown and red pigments of algae allow them to absorb different wavelengths of light therefore determine where each species is found. Green found higher up the shore, red and brown lower shore however each species can exist at any point on the shore
Evidence for upper and lower limits of species
Used for sessile animals and algae
Field observations: observes pattens if where the species occurs
Transplantation experiments: take species out of their zone and see how long they survive and if they do then it’s not abiotic factors that are setting its vertical limits
Lab culture studies: culture species in a more extreme environment than in the field this shows what abiotic stress sets the limit
What are factors setting the lower limits of sessile organisms and algae
Unlikely to be abiotic as they are close to the sea
more likely to be biotic such a competition predation and grazing
