Study notes for spring semester labs

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University of Toronto St. George
Ingrid L.Stefanovic

CHAPTER 6 Eutrophication - PURPOSE: - Aquatic environments susceptible to pollution o Ex. eutrophication: continuous pollution from agricultural run-off or sewage outflows (human or animal) Fertilizers and sewage, being high in nitrogen and phosphorous, increase concentrations to too-high levels and numbers of algae and algae-eaters Stages Algal bloom covers water surface, kills plants below from lack of sunlight Short-lived algal cells decompose and accumulate High oxygen levels, green algae predominate; low oxygen levels, cyanobacteria dominate Bacteria feed on dead matter, using oxygen and releasing carbon dioxide and toxic compounds Aquatic organisms, both plant and animal, deprived of oxygen die - Experiment o To observe the effects of no-fertilizer (control), moderate-fertilizer, and high-fertilizer treatments on aquatic environment containing phytoplankton and Salvinia o Phytoplankton Unicellular, photoautotrophic aquatic organisms, may form multicellular colonies or filaments o Salvinia molesta (kariba weed) Free-floating water fern, pair of leaves above water and connecting stems and divided leaves below water Asexual o Water quality parameters Conductivity Total amount of dissolved ions in water, measured in microSiemenscm (cm) Polluted waters have higher conductivity than unpolluted waters Indirect indicator of salinity, detecting chloride ions from salt Sources: wastewater from sewage treatment plants and septic systems, urban run-off from roads, agricultural runoff Dissolved oxygen Required for cellular respiration Dissolved in water by diffusion from surrounding air, aeration of water tumbling over falls and rapids, and photosynthesis Split from water only by primary producers Oxygen levels reduced through overfertilization Biomass of aquatic plants increase, using up much of available oxygen Dead plants feed oxygen-using bacteria Nitrate (nitrogen combined with oxygen) Essential for plant growth Responsible for inducing growth in coastal plants Sources: fertilizer runoff, leaking septic tanks and cesspools, manure and animal wastes, car exhaust discharges Nitrate and soil being both negatively charged, nitrate rapidly goes through soil into drainage water pH Scale from 0 (highly acidic) to 14 (highly basic) Usual fish pH tolerance between 5.0 to 9.0 Factors affecting pH Age young lakes are basicalkaline, but become more acidic for build-up of decaying organic materials that release harmful, pH-lowering carbonic acid Chemicals discharged by natural environment, communities, industries Phosphorous Essential for plant growth Responsible for inducing growth in freshwater plants Stimulate growth of plankton and aquatic plants in proportion to phosphate concentration Sources: fertilizers, pesticides, human and animal wastes, phosphate-rich rocks, wastes from laundries and industries Turbidity Optical property of water to scatter and absorb light; lights ability to pass through water Depends on how much suspended material is present high turbidity when water cloudy Causes: plankton, soil erosion Measured by spectrophotometer, determining amount of light absorbed Increased turbidity interferes with sunlight penetration, reducing plant growth and available dissolved oxygen CHAPTER 7 Comparative Vertebrate Morphology - PURPOSE - Evolutionary significance of bones o All vertebrates built from same general body plan, having descended from an ancestral species - Ecological significance of bones o Understanding functional significance of morphological variation allows inferences about ecological aspects of a species - Overview o Vertebrates have bilateral symmetry o Endoskeleton divided into Axial skeleton: Skull houses brain and sense organs Spine provides rigidity and support to body Ribs provide sites for muscle attachments, strengthen body wall, protect vital organs Appendicular skeleton: fins and paired limbs Responsible for locomotion, handling food, etc. - Skull Anterior: mouth o Anterior portion houses olfactory and taste receptors, teeth Posterior: tail o Posterior portion protects brain, houses auditory apparatus Dorsal: top view Where skull attaches to rest of body Ventral: bottom view o Middle portion houses visual receptors o Mammalian skull Skull formed from many bones joined at sutures Cranial sutures less obvious in small and old mammalian skulls, invisible in birds Bilaterally symmetrical Occipital bones: located at posterior end of skull, where head connects to the rest of the body Auditory structures: ears, located slightly anterior Orbital region: eyes, located dorsally Rostrum: snout, located anterior of orbits Houses both nasal passage and in most mammals, teeth Lower jaw: separate part of the skull and joins with skull on the side of skull near the ears No. of Brain - Braincase condyles size o Size and structure of brain generally increased during vertebrate Mammal 2 Large evolution Bird 1 Medium o Estimated from cranium volume and skull size Frog 2 Small o Features Foramen magnum: large hole leading into the braincase Occipital condyles: projections on the edges of the foramen magnum Joins with first vertebra in the neck This type of articulation and number of attachment points have changed evolutionarily
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