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Aquariums – Miniature Oceans (part 1) The main goal • To highlight a few of the versatile ways aquariums can be used in the classroom to demonstrate fundamental concepts in biology, chemistry, and earth science • To show the utility of having an aquarium in the classroom is that there is a “one-time” cost in which you can refer to over the course of the year to help leverage lesson plans What are the main components of an aquarium? How to replicate the oceans? • Light • Water movement • Filter (what makes a good filter and why) – Chemical – Physical – Biological • Salt (depends on the system) • Research, Research, Research In other words: habitat recreation Salinity DIY hydrometers and Salt Mixing Goals • To introduce students to a major property of seawater • Encourage students to relate chemical properties (i.e. ion concentration) to physical properties (i.e. density) • Illustrate a simple method to harness physical properties of seawater to estimate a chemical parameter, salinity Salinity How much salt is there in 1 kg (1L) of seawater? What are the chemical components of salinity? 3.5% or 35 ppt (‰) Na+, Cl-, Mg2+, Ca2+, K+, Sr2+, Br-, F-, I-, SO42-, HCO3-, BO33-, SiO32How do these ions get concentrated in the oceans? Weathering of rock by rain removes ions from the land, rivers bring them to the oceans, evaporation removes fresh water leaving the ions (salt) behind in the ocean basins How do you think warming will affect salinity based on this simple diagram? Salinity – Why is it important? • Key driver of ocean density – What are the implications? Stratification, defining oceanographic regions – Impacts microbial communities Impact Biogeochemical – How can this be influential in the cycles, alter food web oceans? dynamics • Sensitive to Climate Change – How could global warming influence surface salinity? Increased evaporation could increase salinity at the equator or at polar regions increasing freshwater from melting ice could decrease salinity Activity 1 – Make and calibrate hydrometer • Fill Clear bottle with enough sand to keep it floating vertical (~1/4 full) • Place bottle in saltwater of known salinity • Take bottle out of water and use marker to mark the water line* and write the known salinity * You may need to adjust the amount of sand to achieve a workable waterline Activity 2 – Mixing Saltwater • Collect 8L of water • Add 240g or ~ 1 cup of salt • Mix • Check Salinity with your homemade hydrometer • Is it higher or lower than your calibration mark? 8L water + ~ 1 cup salt Salinity – Follow up • What physical property are we using as a proxy to check a chemical parameter of seawater? Density • How will you be able to tell if you need to add more salt or more water to your freshly mixed salt based on your hydrometer reading? – If the mark is below the water line? Salt, why? – If the mark is above the water line? Water, why? Nutrient Testing Testing nutrients between heavy bio-load and light bio-load systems Goals – Challenge students to draw connections between water chemistry and biological activity – Introduce students to simple tests for measuring nutrients and water column diagnostics – Familiarize students with the major nutrients in ocean ecosystems Microbes and Chemical Cycles • Microbes are everywhere • They are not all bad, in fact many of them carry out critical ecological functions that keep environments healthy • 1mL of seawater can harbor 100 of thousands to millions of microbes • Crucial link between chemical energy and higher trophic levels in food webs Microbial Filter – Moving Nitrogen Fish + food O2 NH3 + NH4+ (Fish waste) Ammonia Oxidizers O2 NO2(Bacterial waste) Nitrite Oxidizers NO3(Fertilizer for primary productivity) How does this process differ in oceans? It only differs in that it is half of the cycle. The other half if carried out in sediments or low oxygen water columns. Why is it important to remove these nutrients from the aquarium? Ammonium disrupts neuron charge balance What compounds are toxic to fish and inverts? Ammonia/Ammonium (NH3/NH4+) & Nitrite (NO2-) Why are these compounds toxic? NH4+ NH4+ NH4+ NH4 + NH4+ Nitrite irreversibly binds to the iron hemoglobin, preventing oxygen utilization Activity 1 – Nutrient Testing • Collect 15mL of water from each aquarium • Following the instructions on the kit • Dip the test strip into the water sample • Check the strips against color key on kit • Record values from each test • Plot the values on the graph proved By looking at the systems, which one do you think will have higher nutrient concentrations? Activity 1 Questions Values in ppm • Are these healthy levels compared to pristine reefs? • What factors may influence these differences? What are consequences • Predict how the nutrient concentrations will change over time? What could be mediating these changes? Natur al reef Ammonia (NH3/NH4+) 0.2 Nitrite (NO2-) 0.5 Nitrate (NO3-) 1.2 Ammonia (NH3) 8 Concentration (ppm) • Why do the tanks differ? Chemical 6 Heavy bioload Nitrite _ (NO2 ) Nitrate _ (NO3 ) 10 100 8 80 6 60 4 40 2 20 0 0 4 2 0 Light bioload Activity 2 – Gram stain bacteria Goals – Challenge to students to think about microorganisms in seawater – To understand linkages between nutrients and microorganisms – Introduce simple methods for visualizing bacteria – Introduce students to microscopes Activity 2 – Gram stain bacteria Based on activity 1, which system should have a more dense bacteria population? • • • • • • • • • • • • • • • • • Take 0.5 mL of water from each tank with disposable pipette Place a thin, dime size amount water on slide. Allow to air-dry Pass the smear through a flame 2-3 times to heat-fix. Gently flood the smear with crystal violet and let sit for 1 minute. Gently rinse with water. Gently flood the smear with Gram’s iodine and let sit for 1 minute. Gently rinse with water. Tilt the slide and drop Gram’s decolorizer on the smear drop by drop until it runs almost clear. Gently rinse with water Gently flood the smear with Safranin and stain for 45 seconds. Gently rinse with water Blot dry View under microscope using the 40X objective. To view samples at 100X, first focus in using the 40X objective; then rotate the objectives so that the 40x objective is out of the way, but not all the way onto the 100x objective. Add a drop of immersion oil over the center of the hole where the light is coming through the slide, and then rotate the 100x objective into place. Use the fine focusing knobs to focus in, but be very subtle, because even the slightest slip can cause you to overshoot the depth of focus for the specimen Activity 2 – Gram stain bacteria • How do microbes in the environment differ from those in culture? Less dense, smaller, slow growing… • Do you expect there to differences in lifestyle strategies between different niche spaces? Much like macrofauna, microbes exhibit different strategies to live in very diverse environments: free living, aggregate forming or particle associating, biofilms, migrating, symbionts