Marine BiologyMarine Biology

Intertidal Ecology: Focus on Intertidal Ecology: Focus on Biological InteractionsBiological Interactions

Zonation: Role of Zonation: Role of physical/chemical factors vs. physical/chemical factors vs.

biological interactionsbiological interactions Joe Connell, 1972: HypothesisJoe Connell, 1972: Hypothesis

Physical factors primarily responsible for Physical factors primarily responsible for upper limitsupper limits

Biological interactions primarily Biological interactions primarily responsible for lower limitsresponsible for lower limits

Support for hypothesis?Support for hypothesis?

Effects of Effects of biological interactionsbiological interactions on zonation/distribution in on zonation/distribution in

intertidalintertidal Competition for spaceCompetition for spacePredator-prey interactionsPredator-prey interactionsRole of grazersRole of grazersSymbiotic relationships and species Symbiotic relationships and species

distributiondistribution

Larval ecologyLarval ecologyRole of disturbanceRole of disturbance

Competition for spaceCompetition for space

Example: Vertical distribution of the Example: Vertical distribution of the intertidal barnaclesintertidal barnacles

ChthamalusChthamalus BalanusBalanus

Barnacle zonation (after Connell, Barnacle zonation (after Connell, 1961)1961)

Barnacle zonation in New Barnacle zonation in New EnglandEngland

Competition for spaceCompetition for space Example: Algal distributionExample: Algal distribution

Species with small body Species with small body forms initially settle and forms initially settle and grow (opportunistic)grow (opportunistic)

Slower-growing, larger Slower-growing, larger forms outcompete if no forms outcompete if no disturbance occursdisturbance occurs

Competition for spaceCompetition for space

Example: Example: Lottia giganteaLottia gigantea (owl limpet) (owl limpet) territorialityterritoriality

Competition for spaceCompetition for space Example: Mussel bed successionExample: Mussel bed succession

Predator-prey interactionsPredator-prey interactions

Example: Example: Pisaster ochraceus Pisaster ochraceus and the mussel and the mussel Mytilus californianusMytilus californianus

Caging experimentsCaging experiments Follow-up (14-17 yrs)Follow-up (14-17 yrs) Comparisons to Chile and New Zealand studiesComparisons to Chile and New Zealand studies

Bob Paine’s experimentsBob Paine’s experiments

Castro and Huber, Fig. 11.22

Fig. 6.18: Fig. 6.18: Pisaster Pisaster ochraceusochraceus as a Keystone as a Keystone

speciesspecies

Fig. 6.19: Natural experiments on Fig. 6.19: Natural experiments on New England coast (Menge and New England coast (Menge and

Lubchenco)Lubchenco)

Predator-prey interactionsPredator-prey interactions

Example: Example: Nucella sp.Nucella sp.

Predatory snailPredatory snail

Excretes enzymes with Excretes enzymes with an accessory boring an accessory boring organ to dissolve organ to dissolve “shell” of barnacles“shell” of barnacles

Has operculum: Has operculum: enables it to retreat enables it to retreat into shell at low tideinto shell at low tide

Predator-prey interactionsPredator-prey interactions

Distribution within a zoneDistribution within a zoneOystercatchers affect limpet distributionOystercatchers affect limpet distribution

Black oystercatcher (Pacific)Black oystercatcher (Pacific) Variable oystercatcher (New Zealand)Variable oystercatcher (New Zealand)

Role of grazersRole of grazers

Limitation of algae by Limitation of algae by grazersgrazers

OverviewOverview

Case study: Case study: Katharina Katharina tunicatatunicata (chiton) (chiton)

Role of grazersRole of grazers

Maintenance of diversity by grazersMaintenance of diversity by grazers Example: Effects of snails on algal diversity in a Example: Effects of snails on algal diversity in a

tidepool.tidepool.

Role of grazersRole of grazers

Grazing deterrentsGrazing deterrents MorphologicalMorphological Chemical defensesChemical defenses Crustose vs. erect Crustose vs. erect

formsforms Size refugesSize refuges

Limitation of grazers Limitation of grazers by algaeby algae

Symbiotic relationshipsSymbiotic relationships

One species creating a suitable habitat One species creating a suitable habitat for anotherfor another Example: Mussel bedsExample: Mussel beds

Symbiotic relationshipsSymbiotic relationships

Mutualistic relationshipsMutualistic relationships Example: Anthopleura elegantissimaExample: Anthopleura elegantissima