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Aquariums – Miniature Oceans (part 2) Photosynthesis, Respiration, and pH Goals – Challenge students to link CO2 concentrations and pH values – Challenge students to think of photosynthesis as a sink for CO2 and buffer against acidification – Expose students to simple experiments that connect respiration and CO2 to increasing acid levels Ocean Acidification • Increasing CO2 leads to more carbonic acid (H2CO3) and pH of the ocean decreases • Impacts organisms with calcium carbonate components – Corals, Snails, some phytoplankton, etc… • This is a problem as trends in CO2 production are increasing How could photosynthesis affect pH in a closed system like an aquarium? If photosynthesis uses CO2, CO2 should decrease and pH should increase (become more basic) Experimental Procedures 1. Fill the clear plastic bottle about half-way with water. 2. Drop enough BTB into the glass to make the water turn a bl Activity 1 – Bromothymol Blue Assay 3. Using the straw, gently blow into the water solution for 30 s yellow. Do not allow students to blow into the straw unle not mistakenly drink the solution (it is toxic). Ocean Acidification Straw Experiment • Add 50mL water to a clear bottle Introduction Bromothymol blue (also known as bromothymol sulfone phthalein and BTB) is a chemical indicator for weak acids and bases and can be used to demonstrate ocean acidification. Exhaling through a straw into a BTB solution will result in a dramatic color change as carbon dioxide is converted into carbonic acid. This demonstration takes about a minute. • Add ~20 drops of BTB or enough until solution becomes blue Materials Bromothymol blue (BTB) in a bottle Straw Clear plastic bottle Water Experimental Procedures 1. Fill the clear plastic bottle about half-way with water. • Using a straw, gently blow into the solution for 30 seconds. The solution will become yellow, indicating that the solution has become a weak acid. before blowing straw 2. Drop enough BTB into the glass to make the waterNeutral turn a solution blue color (about twentyinto drops). Slightly acid 3. Using the straw, gently blow into the water solution for 30 seconds. The solution will turn Explanation & Discussion yellow. Do not allow students to blow into the straw unless you are confident they such will as burning fossil fuels Start by explaining that human that activities not mistakenly drink the solution (it is toxic). excess CO dissolves in the ocean where it gets converted to an acid 2 acidification" is harmful to many types of marine life, such as corals that this experiment simulates ocean acidification by blowing CO2 in converted to an acid and causes the BTB solution to change color fr (mildly acidic solution). To see how this relates to current C-MORE research, refer to the Sta • Do not inhale! Or drink the BTB solution Neutral solution before blowing into straw Clean up 1. Dispose of the BTB solution down the drain and run the wat rinse the glass. Wash straw thoroughly. Slightly acidic solution after blowing into straw Explanation & Discussion Start by explaining that human activities such as burning fossil fuels put CO2 in the air, and some of this excess CO2 dissolves in the ocean where it gets converted to an acid. This process of "ocean Activity 1 – Questions • How does our breath turn water into a weak acid? No, microbes and plants break • Is respiration done only by down organic matter with oxygen producing CO2 (i.e. animals? respiration) • What other human activities produce CO2? Why are they so impactful? Burning fossil fuels and deforestation. These disrupt the balance between photosynthesis and respiration, leading to excess CO2 Activity 2 – Checking pH between light and dark aquariums • Check pH using test strips between the light and dark aquariums • Check pH using a pH probe Questions • Is there a difference between the two tanks? Why? • Is this difference large enough to make an impact on organisms or food webs? Coral Dissections Goals • Introduce students to microbial symbioses and corals • Provide basic introduction on microscope use • Encourage students to think about the importance of organism interactions and their roles in ecosystem health (e.g., why does bleaching occur?) Coral – The great host • Micro – Zooxanthellae • photosynthesis – Bacteria • Antibacterials • Gut microbiome • Macro – Invertebrates – Fish Stained bacteria Photosynthetic zooxanthellae Anemone fish will host them As will shrimp and crabs Coral Polyp Anatomy The coral we’ll be working with Discosoma • Large polyp • No tentacles • Soft coral (does not have a calcium skeleton) • Common in the aquarium trade • Highly diverse Palythoa • Small polyp • Short thin tentacles • Soft coral (does not have a calcium skeleton) • Common in the aquarium trade • Highly diverse Activity – Coral Dissection • Select 1 polyp of each specimen (Actinodiscus and Palythoa) • Examine structure of each intact coral under the dissection scope • Using a scalpel, carefully make an incision around the edge of the coral • Identify zooxanthellae symbionts Coral Dissection – follow up questions • Are there any differences between zooxanthellae symbionts in the two species? • Why is coral bleaching an indicator of reef health? • Why is the symbiosis between the zooxanthellae and coral important? Bioluminescence & Coral Fluorescence Goals • Introduce students to the topic of bioluminescence and fluorescence • Challenge students to critically think about biologically produced light in the oceans and its potential uses • Link microbial symbioses and bioluminescence to living strategies Bioluminescence Videos https://www.youtube.com/watch?v=9HXXQBz6Vv0 https://www.youtube.com/watch?v=oKjFVBVGad0 What are some of the purposes of bioluminescence? Are bacteria the only organisms that can bioluminesce? Do you think it would be more/less beneficial to bioluminesce yourself, or to host bioluminscent bacteria in a symbiotic relationship? Cost/benefits? Corals fluoresce under certain light wavelengths This a relatively common phenomenon, although the benefit of coral fluorescence remains unclear What are some potential reasons why corals fluoresce? Fluorescence Activity • View a culture of Vibrio harveyi in the dark and discuss bioluminescence • View coral under 460nm light to view fluorescence discuss fluorescence Bioluminescence & Coral Fluorescence – Follow up questions • Does bioluminescence begin immediately after the lights go out? Why or why not? How does bioluminescence differ between V. harveyi in liquid culture, versus on agar plates? • Is all bioluminescence caused by symbionts? • What are the possible benefits to producing your own light in the deep ocean? • Compare benefits of deep bioluminescence to surface planktonic bioluminescence • How can predators and prey utilize bioluminescence? • Why would some corals reflect certain wavelengths of light to emit their own light? • What could be some drawbacks?
