Ecology 3/15/2017. Today. Autotrophs. Writing Assignment: What does it mean. Last readings on Chlamydomonas populations

Transcription

1 Chlorophyll measured in this assay is an indicator of algae levels University College Campus Bayou Average Spring 2008 Fall Spring Fall Spring Fall Spring Fall Spring Fall Spring Fall Spring Fall Spring Fall Spring Fall Spring /15/2017 Ecology Today Last readings on Chlamydomonas populations Clean the test tubes (Scrub, not just rinse) Remove marking: use alcohol (don t drink it) Remove Chlamydomonas rings inside the test tube In-class Writing Assignment V (same deal as last week) Discuss about your formal writing assignment Your hypothesis Your data from lab experiment (what did you see?) Data from the field (do the same conclusions hold for field measurements. If not, why?) Writing Assignment: What does it mean Lots of numbers, Make it meaningful in terms of the living organisms in the lakes. Chlor ophyll (A430) = Autotrophs Primary producers Bring nutrients into the system e.g. Nitrogen as nitrate Phosphate Light converted to chemical energy Consume CO 2 and O 2 Produce O 2 Decay will return nutrients to system Chlorophyll indicator of levels Oxygen production indicator of levels GPP (gross primary production) 1

2 Heterotrophs Consumers Depend on autotrophs to bring nutrients and energy into the system What organisms live in the University Lake System? Eukarya Consume O 2 Produce CO 2 Waste returns nutrients (nitrogen and phosphorus) to the system Oxygen Consumption indicator of levels especially in the spring when respiration by autotrophs is at low levels Domains Bacteria Eukarya Archaea? Archaea Bacteria What organisms live in the University Lake System? Kingdoms Fungi Animal Plants Protist Archaea?-low oxygen sediments Bacteria Autotrophic: Bluegreen Algae Cyanobacteria Heterotrophic: E. coli and others Decomposition, Photosynthesis, Nitrogen Cycle Bacteria 2

3 LSU Main Lake Phytoplankton Observations Based on our microscopic observations of Louisiana State University s main campus lake, we concluded that both filamentous and colonial cyanobacteria were dominant. The most dominant species was Cylindrospermopsis, a harmful algal species which produces the hepatotoxin, Cylindrospermopsin. However, other phytoplankton groups were also observed, including green algae (Chlorophyta), euglenoids (Euglenophyta), and golden-brown diatoms (Bacillariophyta). Raphidiophis cf curvata? (cyanobacteria) Cylindrospermopsis sp. (cyanobacteria) Ana Christina Garcia Nitzschia sp. (diatom) Merismopedia sp or Microcystis cf verdis Microcystis sp. Diatom sp. Cylindrospermopsis sp. 3

4 Cyanobacterial chain Scenedesmus sp. (chlorophyta) Protist Microscopic Unicellular Eukaryotes Autotrophic: e.g. Diatoms & Dinoflagellates Heterotrophic: e.g. Paramecium & Amoeba Plants Autotrophic Unicellular Algae Multicellular Algae Multicellular flowering plants 4

5 Chlamydomonas Animals Autotrophic Plant One of many possible species of unicellular algae in the lake system Contains Chlorophyll Consumes and uses oxygen Converts light to chemical energy Uptake nitrogen and phosphate making them available for heterotrophs Heterotrophic Microscopic e.g. hydra Small e.g. insect larva, worms Macroscopic - e.g. Fish Air Breathing - e.g. Turtles How View Organisms in the Lake? In-class Writing: WA2 graph Videos in common folder Microscopes with lake water Alternate and Null Hypothesis Graph of Aquatic Data. 2-3 lines on trends Which hypothesis should be accepted based on the graph. This means they may have to do 2 graphs if this is how they are setting 5

6 Writing Assignment 2 Abiotic Factors - Temperature Cover Sheet Title General Research Question. Population Ecology Experiment, Null and Alternative Hypotheses: Community Ecology Experiment, Null and Alternative Hypotheses. Methods Results. Graph Population Ecology Experiment Graph Community Ecology Experiment References. (Consult your Laboratory Instructor for specific instructions) Most organism have temperature optimum Higher temperatures reduces the amount of dissolved oxygen the water can contain Abiotic Factors Clarity & Depth Abiotic Factors - ph Autotrophs need light for photosynthesis Shallow lakes (2 m) have higher risk of fish kills Most organism have ph optimum Nutrient solubility/availability varies with ph Levels of ph typically rise above 8.5 under vigorous photosynthesis. Higher ph levels reduce the levels of ammonia fish can tolerate. At ph 10 hazardous ammonia levels are lowered to 1 mg/l. ph of 5-6 or lower has been found to be directly toxic to fish 6

7 Nutrients Nitrogen and Phosphate In-class writing Nutrients can stimulate autotrophs Humans are major contributors to the nutrient load Work in groups of 2 for creation of Graphs for In-class writing and WA2 Exposition should be written independently Community Ecology Graph: Abiotic factor vs. Biotic (Chlorophyll or Oxygen production) 2-3 lines on trends Also include general question & hypothesis. (Not on grading rubric) All students will accept their null hypothesis for the community ecology data Data is too noisy and not enough of it to get clear conclusion. Some if this is student collection, most is legitimate variation in the system. 7

8 Population Ecology Writing Assignment Graphs Chlamydomonas and Corresponding Lake Measurement Possible Lake Data Measurement this must be graphed against a biotic factor, either chlorophyll reflecting algae, or the dissolved oxygen measurement reflecting autotrophs or heterotrophs. Scientific Question ph Nitrogen Phosphate Temperature Intraspecies competition Interspecies competition ph Nitrogen Phosphate Temperature This is the hardest to do. Nutrients can limit if more competition Clarity- too many can block light for organisms below Dissolved Oxyen has 2 measures to compare against each other or compare to chlorophyll. --autotroph vs. heterotroph --heterotroph vs. heterotroph Clarity large surface plants block light Nutrients are used by multiple species Chlorophyll vs oxygen consumption (heterotrophs) Is phosphate a limiting factor for algae/autotroph levels in University lake? This is probably better because more data. Is phosphate a limiting factor for algae/autotroph levels this spring in the LSU lake system? Light intensity Gas exchange Clarity This is hard to correlate, but total dissolved oxygen levels can be used. Chlamydomonas experiment determines if it can be a limiting factor. AMMONIA Null: The chlamydomonas population will not change when phosphate concentrations change. Alternative: The chlamydomonas will change when phosphate levels change. Ammonia levels of 0.2 mg/l can injure fish Ammonia levels of 0.1 mg/l usually indicate polluted waters Range in University Lake System mg/l 8

9 NITRITE NITRATE Nitrite is short lived Nitrite levels below 0.5 mg/l seem to have no effect on warm-water fish 0.5 mg/l is okay for warm water fish, but not cold water fish Best rivers have levels of mg/l Range in University Lake System mg/l (Only see 0.5 mg/l once) Range in University Lake System mg/l Phosphate Why do living things need phosphates? Phosphate is a limiting factor in healthy aquatic systems. Phosphate stored in the rock/soil at the bottom of the lake. One reason to dredge and remove dredge for the health of the lakes. Phosphate is not very soluble in water if in the presence of many other chemicals Humans major contributors to phosphate in lakes DNA, RNA Proteins Phospholipids ATP Bones and teeth, insect exoskeleton Biological buffer 9

10 PHOSPHATE Excess fertilizers in Aquatic Systems EPA suggested upper limits for phosphorus levels: Total phosphates should not exceed 0.05 mg/l (as phosphorus) in a stream at a point where it enters a lake or reservoir Range in University Lake System mg/l Ammonia directly harmful to wildlife Blue green algae blooms produce toxins Depletion of oxygen results in heterotroph death, fish kills Why does a Blue Green Algae Bloom Cause Fish Kills? Toxins can be the cause, often not the primary cause Why does a Blue Green Algae Bloom Cause Fish Kills? Blue Green Algae a bacteria - produces oxygen by photosynthesis. Lots and lots of tiny organisms Tiny 10

11 Why does a Blue Green Algae Bloom Cause Fish Kills? Why does excess fertilizer cause oxygen depletion? Initial bloom of autotrophs Autotrophs use oxygen (respiration) as well as producing oxygen (photosynthesis) Large growth blocks light to lower level autotrophs Large die-offs result in mass decomposition Decomposition uses more oxygen than was produced. Blue Green Algae decomposition when it dies uses more oxygen. History of Lakes University Lake System Originally a Cypress Tupelo Swamp (bottomland hardwood forest) 1920s LSU moved to current campus and City Park Lake was formed 1930s WPA project excavated the other 5 lakes First fish kills happened almost immediately Shallow = hot temps up to 35 C High ammonia content always and very high during fertilization season High phosphate levels in water and in sediment Invasive species block light Dangerous bacteria from sewer runoff 11

12 Flooding Referencing Discuss with students whether so much rain will increase or decrease nutrients in the lake system? Will the bayou be different? I can think of arguments either way Lots of web sites with lake health data from around the world EPA Data 12

13 Referencing: Specific to the University Lake System NOLA.com batonrougelakes.or g 13