Freshwater Foodwebs & Communities

Freshwater Foodwebs & Communities - EVPP/BIOL 350...

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EVPP/BIOL 350 Lecture 13 - Freshwater Food Webs and Communities Dr. Kim de Mutsert
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The community concept A community is a group of interacting species Ecological interactions include predation and competition (last week’s lecture) A group of species that fulfill the same role in a community belong to the same functional group A group of species (or functional groups) is often characterized as a community
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Lake communities In lakes, major habitats include the pelagic (or limnetic) zone, the literal zone, and the benthic zone.
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Lake Habitat Regions Littoral zone Ztotal < zPZ Bottom is within photic zone Trophogenic: Psyn>Resp Autotrophs and heterotrophs Supports benthic algae, rooted macrophytes which add structure Biological zonation is strongly influenced by light availability
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Lake Habitat Regions Limnetic zone Ztotal > zPZ, z < zPZ Open water within photic zone Trophogenic: Psyn>Resp Autotrophs and heterotrophs Species that can suspend in water column or actively
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Lake Habitat Regions Profundal zone Ztotal > zPZ, z > zPZ Open water below photic zone Heterotrophs only Suspended, when substrate associated also called benthic zone
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Lake Habitat Regions Benthic zone Bottom For the most part below photic zone Characterized by heterotrophs Zoobenthos: organisms that live in or attached to the bottom
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The players Macrophytes : large leafy plants with attached microscopic periphyton Plankton : Suspended small organisms controlled by currents Benthos : Bottom dwellers Nekton : Larger, mobile organisms
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Typical Macrophytes submersed Floating leaved Emergent
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Plankton Plankton “wanderers” Suspended in the water column May demonstrate limited mobility, but location chiefly controlled by currents Found principally in the pelagic region, but sometimes also in littoral or profundal Phytoplankton: “plant”-like/photoautotrophs Algae, cyanobacteria Zooplankton: “animal”/heterotrophs Rotifers, cladocera, copepods
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Typical Phytoplankton flagellate desmid cyanobacterium diatoms
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Typical Zooplankton Rotifer:grazer on phytoplankton Water flea: grazer on phytoplankton Copepod: grazer on phytoplankton ------------------- 0.5 mm
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Benthos Benthos Organisms associated with the bottom & sediments Found in both littoral and profundal Phytobenthos Includes aquatic macrophytes and benthic algae Zoobenthos Invertebrates of many groups Most diverse in the littoral
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Typical Zoobenthos Midge larvae bivalves Dragonfly nymph
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Nekton Nekton Organisms controlling their own movements Can move freely and inhabit all lake zones Includes fish and larger invertebrates Functional groups include piscivores, planktivores, benthivores and herbivores
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Typical Nekton Bass: a piscivore (fish eater) Catfish: a detritivore (scavenger) Bluegill: a planktivore and benthivore
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Lake Food Web Nutrients like N and P together with CO2 and light stimulate phytoplankton They are fed upon by zooplankton which in turn provide food for juvenile fish
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Overview of the Lake Food Web
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This note was uploaded on 01/23/2012 for the course BIOL/EVPP 350 taught by Professor Kimdemutsert during the Fall '11 term at George Mason.

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Freshwater Foodwebs &amp;amp; Communities - EVPP/BIOL 350...

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