DOC PREVIEW
UCSC OS 130 - Trophic Structure & Food Webs

This preview shows page 1-2-3-27-28-29 out of 29 pages.

Save
View full document
View full document
Premium Document
Do you want full access? Go Premium and unlock all 29 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 29 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 29 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 29 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 29 pages.
Access to all documents
Download any document
Ad free experience
View full document
Premium Document
Do you want full access? Go Premium and unlock all 29 pages.
Access to all documents
Download any document
Ad free experience
Premium Document
Do you want full access? Go Premium and unlock all 29 pages.
Access to all documents
Download any document
Ad free experience

Unformatted text preview:

Trophic Trophic Structure & Food WebsStructure & Food Webs1946, Riley published a simple food web model:PP = 153T - 120P - 7.3N - 9.1Z + 67131947, simplified it to:dN/dt = N(Ph - R) - GTrophic Trophic Structure & Food WebsStructure & Food Webs1946, Riley published a simple food web model:PP = 153T - 120P - 7.3N - 9.1Z + 67131947, simplified it to:dN/dt = N(Ph - R) - GPhytoplanktonNutrientsZooplanktonTrophic Trophic TerminologyTerminology!!Top Down Control:Top Down Control:!!Regulation of ecosystems by predationRegulation of ecosystems by predation!!Bottom Up Control:Bottom Up Control:!!Regulation of ecosystems by physicsRegulation of ecosystems by physics!!Trophic Trophic CascadesCascades!!Influencing any one Influencing any one ““boxbox”” cascades to other cascades to otherboxes, not always linearlyboxes, not always linearly!!The concept of r-K strategyThe concept of r-K strategy!!Food webs versus food chainsFood webs versus food chainsr versus K strategies r versus K strategiesBased on the concept of ‘maximizing’ reproductiveefficiency by balancing offspring versus parenting r < ---------------------------------------------------------------> KRapid Growth Slow growthMultiple offspring Fewer offspringShort Life Long LifeSmall body size Large body sizeInvasive/Transient EstablishedGeneralists SpecialistMargalefMargalef’’s Mandalas MandalaRamon Margalef(1978) updated theidea of r-Kstrategies for theocean…said thatyou can definespecies successionbased on a “phasespace” defined byenergy (turbulence)and nutrientsEcosystems and Energy TransferEcosystems and Energy Transfer!!EcosystemEcosystem: biotic community + environment: biotic community + environment!!ProducersProducers!!ConsumersConsumers!!DecomposersDecomposersEcosystems and Energy TransferEcosystems and Energy Transfer!!Energy is Energy is alwaysalways lost! lost!With each transfer, some material (energy) goes to growthof the individual, some goes to respiration, some goes towaste products, some (can go) to reproduction….Ecosystems and Energy TransferEcosystems and Energy Transfer!!Trophic Trophic Levels:Levels: each level of organismeach level of organism!!Trophic Trophic Transfer:Transfer: percentage of energy percentage of energy!!Food Chains:Food Chains: short, direct transfer of energyshort, direct transfer of energyfrom phytoplankton to apex predatorsfrom phytoplankton to apex predatorsNZPNPZ Models of BiologyNPZ Models of BiologyCirculation/physicsRemineralization timeFeeding efficiencyRespiration, excretionMichaelis-Menten RespirationTemperatureLightMicrobial Food WebMicrobial Food Web!!First recognized byFirst recognized by Azam Azam, extended by, extended byothers (Pomeroy, others (Pomeroy, WiebeWiebe,, Hobbie Hobbie))!!1977:1977: Hobbie Hobbie introduces introduces Acridine Acridine Orange OrangeDirect Counts (AODC)Direct Counts (AODC)•• 1980s-90s: 1980s-90s:Viruses discoveredViruses discovered•• 2000: 2000: Archaea Archaea!!The Microbial WebThe Microbial Web!!Viruses can account for aViruses can account for amajor source ofmajor source ofphytoplankton mortalityphytoplankton mortality!!Bacteria canBacteria canprovide 50% ofprovide 50% ofphytoplanktonphytoplanktonnutrientsnutrients!!Some ecosystemsSome ecosystemscan be netcan be netheterotrophicheterotrophicUp to 20% of thebiomass in theoceans may beassociated witharchaea.What are theydoing?Illustration by S. Cook, Scripps Institution of OceanographyWhat is DOM?Operational definition: organic matter that passes a GF/F filter(nominal pore size of 0.7 !m)DOM = Dissolved Organic Matter; DOC = Dissolved OrganicCarbon; DON= Dissolved Organic Nitrogen; DOP=DissolvedOrganic PhosphorousIncludes1. All (most) viruses2. 50% of bacteria3. Some phytoplankton (chlorophyll)4. Many "submicron particles," e.g. colloidsItems 1-3 generally not big part of DOM pool.Hansell, D.A. and C.A. Carlson (ed) 2002. Biogeochemistry ofMarine Dissolved Organic Matter. Academic Press.Deep water DOC is ca.6000 years old.Same concentration ofdeep DOC is also insurface layer becauseoceans circulate on orderof 1000 years• Divide the DOC poolinto threecomponents:1) Refractory DOM2) Semi-labile DOM3) Labile DOMCole et al. (1988) Mar. Ecol. Progr. Ser 43: 1-10Bacterial Production and NPPBacterial Production and NPPare generally relatedare generally relatedPrimary Production (mg C m-2 d-1)200 400 600 800 1000 1200 1400Bacterial Production (mg C m-2 d-1)0100200300400500N.PacificSubarcticEquatorN. AtlanticNA RingsIndianArcticAntarcticaBacteria roughly follow phytoplanktonSource of organic CLakes & EstuariesArcticSo what is the microbial web?So what is the microbial web?!!About 50% of NPP goes through bacterialAbout 50% of NPP goes through bacterialdegradation (formation of DOM,degradation (formation of DOM,respiration back to inorganic compounds)respiration back to inorganic compounds)!!For For eacheach size class of producer, there size class of producer, there’’s ans anequivalent consumerequivalent consumer!!In terms of new versus regeneratedIn terms of new versus regeneratedproduction, the microbial web is production, the microbial web is HOWHOW the thematerial is regenerated, and the microbialmaterial is regenerated, and the microbialcommunity is community is WHOWHO is responsible is responsibleHow do we measure it?How do we measure it?!!WhoWho’’s theres there!!FlowFlow Cytometry Cytometry!!Microscopy (withMicroscopy (withstains)stains)!!SEM/TEM (viruses)SEM/TEM (viruses)!!Chemical analysisChemical analysis!!WhatWhat’’s theres there!!Chemical analysisChemical analysis!!Radio-datingRadio-dating!!NMR, mass spec, etc.NMR, mass spec, etc.!!Rates (producers)Rates (producers)!!3H-3H-ThymidineThymidine!!3H-3H-LeucineLeucine!!RespirationRespiration!!Rates (consumers)Rates (consumers)!!Fluorescently LabeledFluorescently LabeledBacteria (FLB)Bacteria (FLB)!!Grazer DilutionGrazer Dilution!!Infection/Infection/LysisLysisWho Cares?Who Cares?• Air-Sea flux of:CO2, methane, DMS,oxygen, nitrogen gas• Regeneration ofnutrients• Repackaging oforganic matter• Recycling andoxidation (rather thanexport)SummarySummary!!In the 1970s, the importance of the In the 1970s, the importance of the ‘‘microbialmicrobiallooploop’’ (web) was discovered (web) was discovered!!For each size class of producer, there is anFor each size class of producer, there is anequivalent consumerequivalent consumer!!Approximately 50% of NPP goes through thisApproximately 50% of NPP


View Full Document

UCSC OS 130 - Trophic Structure & Food Webs

Download Trophic Structure & Food Webs
Our administrator received your request to download this document. We will send you the file to your email shortly.
Loading Unlocking...
Login

Join to view Trophic Structure & Food Webs and access 3M+ class-specific study document.

or
We will never post anything without your permission.
Don't have an account?
Sign Up

Join to view Trophic Structure & Food Webs 2 2 and access 3M+ class-specific study document.

or

By creating an account you agree to our Privacy Policy and Terms Of Use

Already a member?