Modern Reef Keeping - Chemistry

1. Modern Reef Keeping - Chemistry

2. Modern reef keeping • Optimal water parameters for reef keeping • Life support • Temperature • Oxygen • Salinity • pH/Alk • Introduction to skeletogenesis • Ca,Alk, Mg • Typical syndromes in aquarium • Secondary elements • K, I, Sr, Fe • Nutrients, Pollutants & Algae • PO4 / NO3 /SiO4 • Sources • Typical algae in reef tank

3. Life support parameters- Temperature, Salinity, Oxygen and pH/Alkalinity. All biological processes occur in aqueous environment Temperature Salinity Dissolved Gasses pH

4. Life support parameters- Temperature Water temperature in the tropic’s range : 22 -30°C (NOAA,WOA98)

5. Life support parameters- Temperature • Temperature • One of the most crucial water parameter in the reef environment with direct impact on: • Dissolved gases and their saturation • Inhabitance’s metabolism • Accuracy of S.G. and pH measurements. • The Key is Stability - Temperature fluctuations of more than 2°C are the main reason for coral bleaching Water temp. rise in 2 degrees

6. Life support parameters- Temperature • Recommended temp in a reef tank: 26-27°C • Closer to natural temp. at most areas where corals are collected from. • Increase metabolism= rapid growth and better immune response

7. Life support parameters- Oxygen Oxygen levels in coral reefs (ppm) DO levels in coral reefs: 4.5-5 mg/l with 80% saturation (NOAA,WOA98)

8. Life support parameters- Oxygen • Dissolved Oxygen • DO is temperature and salinity dependent. • As long as the DO levels are in saturated/ slight below super-saturated , the reef inhabitance can tolerate higher temperature (28-29°C) • Saturated oxygen levels prevent dissolved CO2 buildup and pH drops.

9. Life support parameters- Oxygen • Dissolved Oxygen • Increasing DO: • Protein skimmer • Surface skimmer • Water surface agitation • Can be measured with colorimetric test kit or non-directly but very efficient with RedOx meter. • Super saturation =Micro-bubbles

10. Life support parameters- Salinity Salinity levels in coral reefs (ppt) salinity levels in coral reefs: 33-38 (ppt) (NOAA,WOA98)

11. Life support parameters- Salinity • Salinity • Salinity is the summery of all the dissolved salts mass in volume of water and it is measured as ppt = g/L = ‰ =psu, with refractometers or Conductivity meters (mS). Specific Gravity is the densities ratio between salt water solution and the same volume of pure water at 4°C S.G. doesn’t have units, measured by hydrometer and it is temp. dependent!!! • Salinity affects marine organisms because the process of osmosis. • Na & Cl concentration in the aqueous medium has direct influence on marine organisms metabolism – Coral calcification. • Recommended salinity in reef tank: 33-36 ppt for optimal calcification.

12. Life support parameters- pH. pH levels in coral reefs: 8.05-8.12

13. Life support parameters- pH/Alkalinity • pH and dissolved CO2 • All biological processes occur in specific narrow range of pH. • Optimal Calcification pH: 8.3 • Optimal ammonia removal from gills: 7.8-8.4 (marine fish). • Optimal level for reef tank: 8.2-8.4. • pH levels major influential factor is CO2- alkalinity CO2 + H2O <=> H2CO3 <=> H+ + HCO3- <=> 2H + + CO32- In sea water: (1%) (93%) (6%) • How to prevent pH drops: • Stable alkalinity (buffer) 3-4.5 meq/l • Protein skimming • Water agitation • Organics removal

14. Introduction to Skeletogenesis or coral Calcification • The site : Coral polyp • The lead stars : Ca⁺², HCO₃⁻ • The co-stars: Mg ⁺², H⁺, CO₂, Sr ⁺² • The director: Zooxanthellae • Special effect: Light

15. Introduction to Skeletogenesis or coral Calcification The Zooxanthellae takes CO2 from coral respiration and from HCO3- and convert it to carbohydrates In low concentration Sea Water Mg ⁺ HCO3- Ca⁺² Passive diffusion HCO3- The Carbohydrates are used as fuel for the active transporters g⁺ Coral Tissue ⁺² Active diffusion Mg Mg HCO3- HCO3- HCO3- Ca +2 Ca⁺² Ca⁺² Coral skeleton = Aragonite

16. Introduction to Skeletogenesis or coral Calcification • Optimal conditions for skeletogenesis: • Creating positives ionic gradient from the surrounded water to the inner coral layers. • Balanced quantities of the building blocks. • Proper pH and Salinity • Energy source

17. Introduction to Skeletogenesis or coral Calcification • The Key = Balance ?

18. Introduction to Skeletogenesis or coral Calcification • The role of Magnesium: • “The Buffer “ of the buffer = MgCO3- • Controls precipitation • Controls CaCO3 crystallization = skeletal strength • Important co-factor in zooxanthellae photosynthesis. Mg

19. Introduction to Skeletogenesis or coral Calcification- Typical Reef Syndromes:

20. The role of other important major, minor and trace elements: • Many other elements are used as co-factors in many biological processes. The most important are those that must be replenished on regular basis. K⁺ - Zooxanthellae nutrient, promotes red/pink/ Purple pigments. Incorporate with active membrane transportation pumps (Na/K) Sr⁺² - Increase skeleton strength by controlling the formation of aragonite instead of calcite (Like magnesium) Fe⁺³/Mn⁻² - Important photosynthesis co-factor, Zooxanthellae nutrient, promotes Green pigments. Important co-factor in de-nitrification. I-- Important antioxidant , control Photosynthetic oxygen radicals in Soft and LPS corals. Promote pigments formation and reduce bleaching by UV shock.

21. Pollution and pollutants • Coral reefs develop and flourish only in oligotrophic ocean areas with clear, unpolluted with limited nutrients in the water. • In the natural reef environment, the major nutrients N, P, C are only available for the zooxanthellae (Coral symbiosis) • Pollution – When the nutrients reach to a certain levels they stop being the limited factor in the reef system. High nutrient levels enhances bacteria proliferation and algae bloom- Eutrophication.

22. Pollutants - N

23. Pollutants - N • In natural corals reef: NO₃⁻. < 0.3ppm • Nitrogen forms in the aquarium: NH₃/NH₄⁺, NO₃⁻. • Sources: Organic mater decomposition, fish extracts, tap water, supp., salts, live rocks, coral sand. • Negative effects of high nitrate levels: • Indirect damage to corals by Increasing zooxanthellae densities • Competition with the coral on carbon source (HCO₃⁻) • Intensive photosynthesis – high levels of oxygen radicals. • Coloration • Eutrophication –nuisance algae outbreak. • Treatments • 10-15% weekly water change • NO₃⁻ absorbers –zeolites • Assimilation - Refugium • Enhancing De – nitrification

24. Pollutants – N – De nitrification • De – nitrification - Microbial process of nitrate reduction to nitrogen gas. • Made by at least 10 facultative heterotrophic bacteria strains at anoxic levels – not anaerobic ! ppm< O₂< 0.2 ppm 0>ORP> -180 mv 12NO₃⁻ + 10CH₃OH+ 12H⁺-> 6N₂+10CO₂ +26H2O • Carbon source is the limited factor of the process (also Mo and Fe). • Light inhibit de-nitrification • The process occur naturally in live rocks pores and in the lower sediment (after 3 weeks from starting the cycle) • Filtration methods to control/ enhance de-nitrification: • De-nitrators • Assimilation - refugium • DSB/ Plenum

25. Pollutants - P

26. Pollutants - P • Phosphate forms in marine environment : PO₄³⁻, HPO₃²⁻. • Sources:Organic mater decomposition, fish extracts, tap water, supp., salts, live rocks, substrate. • In corals reef: PO₄⁻. < 0.05 ppm • Negative effects of high phosphate levels: • Direct damage to corals by reducing available Ca ions for coral skeletogenesis. Ca3(PO4)2 formation inhibit CaCO₃ lattice formation. • Increase zooxanthellae densities. • Eutrophication – Cyanobacteria – Toxins. • Treatments • 10-15% weekly water change • PO₄³⁻ absorbers (FeO/OH, FeCl, AlO) • Assimilation - Refugium • Microbial reduction – carbon source.

27. Pollutants - Si • Silicon forms in marine environment : Si(OH)4. Si(OH₃)o. • Sources: tap water, supp., salts, live rocks, substrate. • In corals reef:Si(OH)4 < 0.5 ppm • Important nutrient for sponges and snails. • High level can cause diatoms outbreak for several days. • Treatment: • 10-15% weekly water change • Si(OH)4 absorbers (FeO/OH, FeCl, AlO) • Assimilation – Refugium with sponges • Do nothing- it will leave as it comes.

28. Pollution- The magic circle of polluted tank. Pollution – When the nutrients reach to a certain levels they stop being the limited factor in the reef system. High nutrient levels enhances bacteria proliferation and algae bloom- Eutrophication Organic matter: Fish food and extracts, Dead Bacteria and micro-algae, Coral tissues and mucus NO3 Algae + Oxygen P04 Bacteria Organic matter decomposition reduce dissolved oxygen

29. Pollution- Oxygen demand and RedOx • Many biological process can described as Reduction/Oxidation processes where electrons are transferred from one element to the other. Oxidation – nitrification - NH₃ + O₂ -> NO₃⁻ Reduction –De nitrification - NO₃⁻ + C -> N₂ • All decomposition process requires oxygen as the oxidizer- therefore the oxygen levels will drop followed by a drop in RedOx level (mV). • Increasing the oxygen levels, by removing the organic material out of the system, will increase the RedOx potential. • How to increase RedOx in the reef aquarium: • Good protein skimmer – takes the organics out and insert oxygen. • Ozone- break down organics and oxidize water.

30. Pollution-Eutrophication of Nuisance algae • Nuisance algae – undesired micro-algae or desired algae in un controlled growth (Macro algae). • Micro-algae: • Green hair algae • Blue-Green – Cyanobacteria • Diatoms • All the three will appear naturally during the cycle period. • Macro-algae: • Caulerpa sp. • The dangers of eutrophication : • Competition on nutrients with zooxanthellae& coralline algae • Competition on space • Corals suffocation and shading • Toxins – alleochemicals • Oxygen reduction during the dark periods • Oxygen super saturation during the light hours

31. Pollution-Eutrophication of Nuisance algae • Nuisance algae – Green algae • Most common: Bryopsis, Debresia, Valonia. • Circumstances for outbreak: • Organics accumulation • High nitrate, phosphate and iron levels • Strong lights not with the adequate PAR and color (to much red) or old bubbles. • Damage: • Competition on nutrients with zooxanthellae and coralline algae • Competition on space • Corals suffocation and shading • Oxygen reduction during the dark periods • Oxygen super saturation during the light hours • Treatments: • Organics removal – Protein skimmer • Nutrient reduction - biological processes • Assimilation – Macro-algae refuigium • Physical trimming • Fixing lights issues

32. Pollution-Eutrophication of Nuisance algae • Nuisance algae – Blue green - Cyanobacteria • One of the oldest life forms. • Circumstances for outbreak: • Organics accumulation • Unbalanced N : P ratio or high Phosphate – assimilate nitrogen from atmosphere • Damage: • Toxins • Competition on space • Corals suffocation and shading • Oxygen reduction during the dark periods • Treatments: • Organics removal – Protein skimmer • Phosphate reduction - biological processes. • Assimilation – Macro-algae refuigium • Physical removal

33. Pollution-Eutrophication of Nuisance algae • Nuisance algae – golden brown - Diatoms • Circumstances for outbreak: • Silicates • Damage: • Nothing • Treatments: • Patient ! • If it’s continues- check for Si in the fresh water source.

34. Pollution and pollutants-Summery Organics Reduce oxygen Increase bio - load Increase nutrients Suffocation toxins Calcium accessibility Damage to corals and fish Algae outbreak Suffocation, Toxins, competition with Zooxanthellae

35. Thank you for listening!!! God help us, it’s only the second lecture and we have another 3…