6/27/11. Aquatic Community Ecology (BIOL 312) Summer I. Ecological Principles. What is an ecological community? Ecological Principles

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1 Aquatic Community Ecology (BIOL 312) Summer 2011 Day 1 Outline Introduction, Class Overview I. Ecological Principles II. Life in Water III. Zonation/Vertical Structure For Tuesday: Read Ch 5 Conesus Lake Watershed Characterization Report: pp. 1-3, 9-10, I. Ecological Principles What is an ecological community? An assemblage of actually or potentially interacting species living in the same place and bound together by the network of influences that species have on one another. IV. Lake Community/Ecosystem Ecology Ecological Principles Ecological Principles What are some examples of ecological communities? What are the inherent properties of ecological communities? Rain forest, coniferous forest, coral reef, Assemblage of organisms living on/in one tree Stomach flora of a termite Species diversity Relative abundance of species, dominance Productivity, biomass Trophic structure Seasonality, vertical and horizontal heterogeneity Predator prey interaction affects Competitive interaction effects Ecological Principles II. Life in Water Levels of Ecological Organization Biosphere Ecosystem Community Population I. Life in Water II. Vertical Structure of the Water Column A. Light and Heat B. Stratification C. Mixing Organism 1

2 Comparison of Terrestrial and Marine Communities A. Biodiversity -- Life evolved in water; more species on land (insects and angiosperms) -- More diversity at higher taxonomic categories in aquatic habitats - Of all the species recorded fewer than 15% are in the ocean and most of them live in bottom sediments Comparison of Terrestrial and Marine Ecosystems A. Biodiversity B. Functional/Structural differences in aquatic habitats Plankton: A Community Unique to Aquatic Systems Large macropredators Habitats and planktivores - fewer vascular plants; more algae; phytoplankton - dominant herbivores are small and food webs can have many trophic levels (large herbivores are manatees, iguanas). - larger animals mostly carnivores; except some of the largest animals are planktivores - filter feeding, sedentary lifestyle possible in animals. Units in microns III. Zonation/Vertical Structure in Aquatic Habitats Description of zones in Lakes Riparian Zone 2

3 IV. Overview of Organization of Lake Community and Ecosystem The Ecosystem is the Watershed Epilimnion or mixed layer Agriculture 1571 Kg 54% Residential 1072 kg 37% External Load 181 kg Amount leaving via Outlet Lake Ecosystem A. The Nearshore B. Open Water C. Limiting Nutrients D. Interaction 2075 kg Internal Load 3

4 A. Aquatic Macrophytes and the Nearshore Environment Emergent : rooted and living down to a depth of 1.5 m Floating-leafed: floating leaves are on long petioles; depths of 0.5 to 3 m; nearly all angiosperms Submersed: at all depths within the photic zone but vascular angiosperms only to about 10 m. All provide critical habitat for small fish and invertebrates. Provide habitat for Metaphyton and Periphyton Comparison of Annual Net Productivity of Aquatic Plant Communities Community Type Approximate Productivity Marine phytoplankton 2 mt/ha/yr Lake Phytoplankton 2 FW submersed macrophytes temperate tropical 1 Marine Submersed macrophytes temperate 29 tropical 35 Marine emergent macrophytes 30 (salt marshes) FW emergent macrophytes temperate 38 tropical 75 B. The Offshore Environment Piscivores (large fish) General Types of Phytoplankton dinoflagellates Generalized Open Water Food Web In a Lake Zooplanktivores (fish, large zooplankton) diatoms (small grazers) (large grazer) Rotifers are numerous, primarily herbivores that feed on the smallest algae Large herbivorous crustacea, like Daphnia, and large copepods, graze at high rates and on larger algae 4

5 Typical Open Water Food Web in Lakes C. Limiting Nutrients: Phosphorus - P originates in rocks - It is quickly absorbed by plants - It is adsorbed in sediments C. Limiting Nutrients: Phosphorus Movement of Phosphorus through Aquatic Habitats Phyto plankton - P originates in rocks - It is quickly absorbed by plants - It is adsorbed in sediments Conditions in the hypolimnion become almost anoxic. Most organisms move away from this zone Mixing and renewal of the hypolimnion occurs when the water nears isothermal conditions 5

6 Water quality data from 1910 to 2003 show deeper waters of Conesus Lake are normally depleted of oxygen Anoxic area grows from mid-may thru mid-october until turnover Depth DO (mg/l) Depth Nutrients (Phosphorus) Nutricline SUMMER Condition Algae Conductivity high Redox potential ph low Depth Nutrients (Phosphorus) Nutricline SUMMER Condition Algae Nutrients are Highest in the Hypolimnion, Especially nearest to the bottom. Most phosphorus IN a lake is buried in the Sediments. Depth (m) Depth vs ORP /24/11 0/07/11 2 0/14/11 0/20/11 4 0/27/11 07/18/11 08/08/ ORP (mv) Depth (m) Total Phosphate versus Depth Total Phosphate (ug/l) /07/11 0/20/11 0/27/11 07/18/11 08/01/11 In the presence of high oxygen, Fe 3+ is reduced to Fe 2+ and precipitates as various compounds into the sediment. P adheres strongly to the precipitates Surface Waters In the absence of O 2, the ppt go into solution, Releasing P into the water From Caraco (1993) Oxygen Fe 3+ Ferrous Wheel Fe 2+ algae P Supply In precipitates Anoxic Waters/Sediments

7 Conesus Lake Phosphorus Budget 200 kg External Load 2075 kg 181 kg Amount leaving via Outlet D. Interactions of the dominant inshore and offshore plants Two systems, the nearshore dominated by macrophytes and the offshore dominated by phytoplankton Interact through nutrient utilization, light competition Internal Load IV. Interactions of the dominant inshore and offshore plants Interactions Two systems, the nearshore dominated by macrophytes and the offshore dominated by phytoplankton Interact through nutrient utilization, light competition ` ` Water turbidity is a function of phytoplankton abundance and limits the depth of macrophyte habitation M. Scheffer, et al TREE Quantitative Importance of Interactions is not well known but there is evidence that vegetation has a profound influence in lakes. 7