Salinity Influence on Algal Populations

1. Salinity Influence on Algal Populations Graham Sides Central Catholic High School 9th Grade

2. Rationale Aquatic life forms can be stressed through various processes, some of which involve a change in the concentration of salt. Increasing salinity may result from road salt runoff, industrial processes, and other human activities. Because algae may be utilized in processes such as biofuel production, establishing optimal growth conditions might be helpful

3. Salinity The technical term for saltiness in aquatic environments is halinity, from the fact that halides, or chloride, are the most abundant anions in the mix of dissolved elements In oceanography, it has been traditional to express salinity not as percent, but as parts per thousand (ppt), which is approximately grams of salt per liter of solution Other disciplines use chemical analyses of solutions, and thus salinity is frequently reported in mg/L or ppm (parts per million)

4. Fresh water • Freshwater (<0.5 ppt) is a word that refers to bodies of water such as ponds, lakes, rivers and streams containing low concentrations of dissolved salts and other total dissolved solids • Freshwater can also be the output of desalinated seawater • Freshwater creates a hypotonic environment for aquatic organisms, whose cell membranes might burst if excess water is not excreted

5. Sea water Water from a sea or ocean On average, seawater in the world's oceans has a salinity of about 3.5%, or 35 parts per thousand The average density of seawater at the surface of the ocean is 1.025 g/ml; seawater is denser than fresh water because of the added weight of the salts and electrostriction The fresh water of sea water decreases with increasing salinity and is about -2°C (28.4°F) at 35 parts per thousand.

6. Brackish water • Water that has more salinity than fresh water, but not as much as seawater, and is often hostile to the growth of most plant species • Results from mixing of seawater with freshwater, like estuaries, or it may occur in brackish water aquifers • Human activities can produce brackish water: • civil engineering: dikes and flooding of coastal marshland • Primary waste product of the salinity gradient power process

7. Algae • Algae are a large and diverse group of mostly autotrophic organisms, ranging from unicellular to multicellular forms. • They are photosynthetic like plants, but simple as they lack the many distinct organs found in land plants • All that they need to grow is water, sunlight, and carbon dioxide. • All true algae have a nucleus enclosed within a membrane and chloroplasts bound in one or more membranes. • Algae are most prominent in bodies of water but are also common in terrestrial environments. • Terrestrial algae are usually subtle and far more common in moist, tropical regions than dry ones because of their lack of vascular tissues and other adaptations to live on land.

8. Euglena vs.Chlamydomonas • Unicellular flagellates. • Photosynthetic • Ion channels such as channelrhodopsin are activated by light. • Popular biochemical and genetic research model • A common protist and functions in sunlight. • Commonly cylindrical in shape. • Chloroplasts are clear. • Can also act as heterotroph, absorbing nutrients from decomposed organisms

9. Spectrophotometry Quantitative study of electromagnetic spectra Visible light, near-ultraviolet, and near-infrared and the use of a spectrophotometer: can measure intensity as a function of color or light absorption Important features include the spectral bandwidth and linear range Commonly used in scientific fields such as chemistry, biochemistry, and molecular biology

10. Previous Similar Experiments • The effects of salinity, temperature, and organic and inorganic nutrients on the growth of Raphidophyceae, a unicellular, eukaryotic algae that can live in both freshwater and marine waters in the Adriatic Sea. The results showed that the Raphidophyceae grew better with a temperature increase in seawater. • The effects of salinity on the growth rates of Arctic-sea-ice algae from the Greenland Sea. The results showed that the algae was able to grow better in medium salinities (12.2 PSU to 20.6 PSU)

11. Purpose To test the effects of salinity on algal survivorship/population growth Null Hypothesis and Alternative Hypothesis The salinity will have no significant effect on Euglena or Chlamydomonas population density The population density will increase more with a lower salinity than with a higher concentration

12. Materials 60 watt plant light Temperature stabilizer Large cardboard box 10% NaCl salt solution Euglena gracilis Chlamydomonas rheinhartii Soil water (sterile) Spring water 30 test tubes (13 x 100 mm borosilicate culture tubes) Pipettes (macro + micro) Pipette tips Science kit student spectrophotometer Test tube rack

13. Procedure • An enclosed cardboard environment was created for the algae to grow, including light from an artificial plant light, a temperature controller kept at 30 degrees Celsius • The following ingredients were pipetted into 13 x 100 borosilicate culture tubes: • There was three replicates of each • The growth of both types of algae was monitored every other day for 2 weeks: absorbance at 430 nm in a spectrophotometer • All of the data was recorded in a lab notebook to be presented on a line graph to better show which salinity algae grows best in

14. Assortment of Salinities for Euglena If needed, the test tubes that lost water due to evaporation were refilled back up to 5 milliliters with spring water

15. Assortment of Salinities for Chlamydomonas If needed, the test tubes that lost water due to evaporation were refilled back up to 5 milliliters with spring water

16. P-value = 0.009145 P-value = 0.034822

17. Euglena Growth Statistical Analysis • The data does not support the null hypothesis, but does support the alternative hypothesis • The 0% Salinity had the greatest amount of growth • The growth decreased as the salinities increased • The 5% salinity had the lowest absorbance readings • The lines followed the pattern of decreasing in the beginning, rose in the middle, then dropped sharply at the end • Possible explanation – the Euglena died in the middle of the experiment causing the absorbance readings to decrease rapidly

18. P-value = .000249 P-value = .17677

19. Chlamydomonas Growth Statistical Analysis • Data does not support the null hypothesis, but does support the alternative hypothesis • 0%, 1%, and 2% all had about the same growth at about .123 ppm • The growth decreased as the salinities increased • 5% salinity had the lowest absorbance readings • Lines followed the pattern of rising slightly in the beginning, but then decreasing throughout the rest of the experiment • Possible explanation – the Chlamydomonas died in the middle of the experiment causing the absorbance readings to decrease rapidly

20. Dunnett Testing Chlamydomonas

21. Dunnett Testing Euglena

22. Conclusions and Possible Explanations • Both species of algae grew better in the lower salinities • The Dunnett testing showed that the 3% and 5% salinity in the Euglena was significant in lowering the absorbance • Neither species grew • Possible Explanations • The temperature was too high for the algae, thus killing it • The algae were already dead before experiment began