Aquatic Adaptations - Week 2 PDF

Ecology Week 2 Lecture 4 – Adaptations to Aquatic Environments Water is Critical to Life 2  Properties of water Water Hydrogen sulfide Molecular H 2O H2S formula Molecular weight 1...

Ecology Week 2 Lecture 4 – Adaptations to Aquatic Environments Water is Critical to Life 2  Properties of water Water Hydrogen sulfide Molecular H 2O H2S formula Molecular weight 18 34 Boiling point +100ºC -61ºC Melting point 0ºC -86ºC 3 4 Lake Turnover - Water is densest at 4°, thus: - Lakes rarely completely freeze - Leads to mixing 5  Water as a Solvent Table salt (NaCl) Hard Water 6  Chemistry Review Element: a pure substance (hydrogen, oxygen; a letter from chemical table) Atoms: Building blocks, indivisible Molecule: More than one atom bonded (O2, H20) Compound Molecule: Different types of atoms bonded (H2O, NaCL) Ion: Charged particle (atoms or molecule, eg. Na+, Cl-) Nutrient: substance required by a living organism Solute: substance dissolved in water 7 - Depends on the particular organism (eg. Ca for vertebrates, trees) - Water is critical for flow of nutrients through ecosystems 8 Dissolved minerals: 0% 0.02% 3.4 % 9 Water as a Solvent Table salt (NaCl) 10 Limestone (calcium carbonate) Ca2+ + HCO3-  H+ + CaCO3 11 Percent fresh water 12  Percent fresh water Lakes, rivers, and streams only 0.01% of total water 13  Water Balance Water is essential to organisms: needed for photosynthesis, provides a medium for nutrients Problem: how to maintain water balance?  Salt Balance “Salt balance and water balance go hand in hand” WHY? Salts are located in water When water leaves organism via evaporation, salt concentration increases Solute concentration affects water movement via osmosis  Osmosis Osmosis is the passive movement of water across a differentially permeable membrane, from areas of low solute concentration to high concentration  Osmoregulation Osmoregulation: The mechanisms that organisms use to maintain proper salt balance Water & salt balance Seawater Fish Body Freshwater Freshwater fish: Hyperosmotic body fluids: Higher salt than surrounding water Marine fish: Hypo-osmotic body fluids: Lower salt than surrounding What does this mean for water intake/loss? Freshwater Marine Urea = Nitrogenous byproduct of metabolism  Salmon Life Cycle - Reverse salt pumps in gills, and kidneys change from conserving to expelling salts Carbon 23  Human Body Composition: Carbon H “Building block” of life C Present in all known O life forms 2nd most common element in humans by weight O H C Ultimate source? 24 C6H12O6 + 6O2 ⇔ 6CO2 + 6H2O 25  Obtaining Carbon in Water -10x slower movement 26 27 Case study: Lake Victoria Ecology and Humans 28 -“Discovered” by Europeans in 1858 29  Lake Victoria -Source of the Nile River. -Waterfalls form barrier to Nile fish invading the lake. 30 Completely dried and refilled 3x, latest 14,000 years ago 31  Cichlid radiation: 400 spp in 14K yrs 32 33 34 35 What effects have humans had on this ecosystem? 36 Initially small-scale fishing, sustainable catch… 37 38  39 http://en.wikipedia.org/wiki/Lake_Victoria 40 41 Algal and phytoplanton shade plants/algae below, preventing them from releasing oxygen 42  Singidia tilapia (Oreochromis esculentus) 43 The Nile Perch Lates niloticus 44 45 Algal and phytoplanton shade plants/algae below, preventing them from releasing oxygen 46  Water Hyacinth -First appeared 1989; native to South America 47 48 -Clogged motors -Decreased light below - Increased snails, snakes, mosquitos,(malaria, shistosomiasis) 49 Human Impacts on Lake Victoria High human population: – Overfishing – Eutrophication Introduced fish: Nile perch Introduced plant: Water hyacinth Caused: Massive ecosystem alteration, anaerobic ‘dead zones’, native fish diversity cut in half 50  Economic and Health Consequences Decimated fish populations; eventually even Nile perch abundance Increased spread of diseases – Shistosomiasis (parasitic worms) – Malaria 51  Basic and Applied Ecology Basic ecological research is critical to understanding these effects – Interactions between species – Abiotic requirements (nutrient/sunlight) – Population changes through time 52 53