Communities, Ecosystems, and Biodiversity Definitions of community Organism interactions Ecosystems Different types of communities, ecosystems Biodiversity.

Communities, Communities, Ecosystems, and Ecosystems, and

BiodiversityBiodiversity

Definitions of communityDefinitions of community

Organism interactionsOrganism interactions

EcosystemsEcosystems

Different types of communities, ecosystemsDifferent types of communities, ecosystems

BiodiversityBiodiversity

Community DefinitionsCommunity Definitions

All organisms in an areaAll organisms in an area

Also includes: interactions, structure, organizationAlso includes: interactions, structure, organization

Can also include recurrenceCan also include recurrence

The biological component of ecology (interactions The biological component of ecology (interactions between an organism in an area plus the environment)between an organism in an area plus the environment)

Superorganism (Clements, 1926) vs. Superorganism (Clements, 1926) vs. Individualistic responses (Gleason, 1929)Individualistic responses (Gleason, 1929)

Organism InteractionsOrganism InteractionsCompetitionCompetition

Food, space, nutrients, lightFood, space, nutrients, lightNiche concept and guildsNiche concept and guildsDominanceDominanceOrganisms partition resources so don’t competeOrganisms partition resources so don’t competeDominant organismsDominant organisms

Organism InteractionsOrganism InteractionsPredationPredation

Hunting: chemosensory, visual Hunting: chemosensory, visual predator avoidance predator avoidance

Morphology, chemistry, behaviorMorphology, chemistry, behaviorPredators and trophic pyramidsPredators and trophic pyramids

Organism InteractionsOrganism InteractionsEpibiosisEpibiosis

relationships: mutualists, parasites, commensalrelationships: mutualists, parasites, commensal

Keystone species and “species of great effect”Keystone species and “species of great effect”

Why study marine Why study marine communities?communities?

Understand trophic webUnderstand trophic webRecognize keystone species, species of great effectRecognize keystone species, species of great effectConservation practicesConservation practicesFisheries impacts, sustainable harvestingFisheries impacts, sustainable harvestingImportance of previously unknown processesImportance of previously unknown processes

Microbial loop, primary productivity and ironMicrobial loop, primary productivity and ironUnderstand impact of pollutantsUnderstand impact of pollutants

Example: Sea Grass Bed, Example: Sea Grass Bed, TXTX

Annually dynamic, but over time, averages out to similarityAnnually dynamic, but over time, averages out to similarityDead versus live assemblage comparisonsDead versus live assemblage comparisons

In current near estuary, fully marineIn current near estuary, fully marine

Example: Sea Grass Bed, Example: Sea Grass Bed, TXTX

Sea grass: baffles sediment:Sea grass: baffles sediment: environment mediator, species of great effectenvironment mediator, species of great effect

Clams, gastropods, polychaete worms, arthropods, othersClams, gastropods, polychaete worms, arthropods, othersLarval settlement at different times of year per speciesLarval settlement at different times of year per species

Clams in springClams in springSummer: many dead juvenile clam shells in sedimentSummer: many dead juvenile clam shells in sediment

Seagrass, algae: primary producersSeagrass, algae: primary producersGastropods: grazers, predators Gastropods: grazers, predators Clams: detritovoresClams: detritovoresMussels and polychaetes: filter feedMussels and polychaetes: filter feedArthropod and fish: predators Arthropod and fish: predators Seagrass substrate for microbes, algae Seagrass substrate for microbes, algae Microbial loop recycles nutrientsMicrobial loop recycles nutrients

ECOSYSTEMECOSYSTEMEcosystem = community + environmentEcosystem = community + environment

ScalessScaless

Environment = physical aspectsEnvironment = physical aspectsTopography, sediment type, currents, lightTopography, sediment type, currents, lightOften anthropogenic effects: pollutants, sedimentsOften anthropogenic effects: pollutants, sediments

Dynamic: always changing on fine temporal scalesDynamic: always changing on fine temporal scalesOver geologic time: slow and quick changesOver geologic time: slow and quick changes

Example: Hydrothermal Example: Hydrothermal VentsVents

Deep ocean, near “black smokers”Deep ocean, near “black smokers”Very high T water, sulfur, other chemicalsVery high T water, sulfur, other chemicalsNo light, low O2No light, low O2

Tube worms, bivalves, shrimp, crabs, eelsTube worms, bivalves, shrimp, crabs, eelsSymbiotic relationship with sulfur-fixing bacteriaSymbiotic relationship with sulfur-fixing bacteriaSimilar to photosynthesis, but some predationSimilar to photosynthesis, but some predation

Nutrient input from smokers, detritusNutrient input from smokers, detritusOrganisms tightly coupled with environmentOrganisms tightly coupled with environmentOpen or closed system? Patches far apart, smokers ltd timeOpen or closed system? Patches far apart, smokers ltd time

Organisms have to get there somehow!Organisms have to get there somehow!

BiodiversityBiodiversitySpecies richness: how many speciesSpecies richness: how many species

Can be studied on community/ecosystem scale or globallyCan be studied on community/ecosystem scale or globally

Ocean extremely diverseOcean extremely diverseReefs more diverse than rainforest!Reefs more diverse than rainforest!Most of study of biodiversity through time marineMost of study of biodiversity through time marine

Diversity greatest on continental shelves, coastsDiversity greatest on continental shelves, coastsLight, nutrients --> primary productivity highLight, nutrients --> primary productivity high

Diversity in deep ocean also highDiversity in deep ocean also highNutrients, O2Nutrients, O2But…patchyBut…patchy

ExtinctionsExtinctionsLocal extirpations --> global extinctionsLocal extirpations --> global extinctionsSmall, background extinctions --> mass extinctionsSmall, background extinctions --> mass extinctions

Background extinctions:Background extinctions:local to regional; one or few specieslocal to regional; one or few species

Causes of background extinction:Causes of background extinction:Speciation, outcompete, invader, environment, diseaseSpeciation, outcompete, invader, environment, disease

Mass ExtinctionsMass ExtinctionsInvolve MANY species, globalInvolve MANY species, global5 major mass extinctions:5 major mass extinctions:

Largest: P/Tr, 250MYA – 80 to 95% marine lifeLargest: P/Tr, 250MYA – 80 to 95% marine lifeMost well known: K/T, 65MYA – 40% marine lifeMost well known: K/T, 65MYA – 40% marine life

Mass ExtinctionsMass ExtinctionsCauses of mass extinction:Causes of mass extinction:

Climate changeClimate changeocean circulation changeocean circulation changeVolcanismVolcanismExtraterrestrial impactExtraterrestrial impactSea-level changeSea-level changeHuman factorsHuman factors

A human-caused mass A human-caused mass extinction?extinction?

Trophic changesTrophic changes