Phytoplankton s Effect on Ocean Acidification

Transcription

1 Phytoplankton s Effect on Ocean Acidification I. Problem Statement: What effect does the addition of two species of Tetraselmis, PLATP and PLY429, have on and alkalinity in ambient and low environments? II. Collected Information: The ocean s chemistry is changing rapidly every day and not in a favorable way. This is because of ocean acidification, which is the decrease in the ocean s over time due to carbon dioxide (CO 2 ) in the atmosphere entering the ocean. The process of ocean acidification is as follows: CO 2 from the atmosphere is dissolved in the ocean and reacts with water (H 2 O) to create carbonic acid (H 2 CO 3 ) which lowers the level in the ocean and breaks down calcium carbonate (CaCO 3 ) shells (Logan, 2010, p. 19). The reason ocean acidification is so prominent today is because about one-third of the CO 2 in the air has been absorbed in the ocean over the past 100 years, which not only reduces the of seawater, but also increases the partial pressure of CO 2 (Kurihara, 200, p. 275). Also, most CO 2 in the atmosphere has been emitted by mankind and absorbed in the ocean since the beginning of the industrial revolution. Compared to change of temperature due to global warming, which is very unpredictable due to the varying causes; ocean acidification is easier to predict the rate of change over long periods of time (Logan, 2010, p. 19). Through data collected over time it is easy to see these changes over time. Before the industrial revolution, the ocean s acidity was about 250 parts per million (ppm), today it is about 390 ppm and predicted for the future it will be 400 ppm. The current rates of increased atmospheric CO 2 are also significantly faster than any records of tens of millions of years suggest (Talmage & Gobler, 2010, p ). Another source predicts that the CO 2 concentration in the year 2100 will be between 750 to 00 ppm with a 150% increase in the concentration of hydrogen ions (H + ) (Logan, 2010, p. 19). Ocean acidification matters for a variety of reasons. Some reasons being that it may affect the calcification process of calcifying organisms, a lower affects acid-base regulation, and an increase in dissolved CO 2 may alter the ability for producers to photosynthesize (Logan, 2010, p. 20). Oysters and Clams are examples of marine organisms

2 that have shells made of CaCO 3, which go through the calcification process to form their shells. The reasons that these organisms are so important not just in the ecosystem, but the harvest of mollusks are economically important to the United States, with their harvest bringing in about $750 million annually (Talmage & Gobler, 2010, p ). The effect of ocean acidification on calcifiers affects each stage of their development differently. Life stages of calcifiers are as follows: fertilization, cleavage, planktonic, larva, settlement, metamorphosis, juvenile, adult, and reproduction stages (Kurihara, 200, p. 276). Organisms like this use the calcium and carbonate ions to form their shells, used for skeletal support and protection (Logan, 2010, p. 20). Strong shells are vital to these organisms, including oysters, one reason being that it is the first line of defense for larvae or juvenile shellfish. It also provides physical support for internal organs, and protects from predators. Therefore, with an increase in CO 2 concentration the organisms would become more vulnerable to environmental predation, and more susceptible to juvenile mortality. The reason that this occurs is because as CO 2 increases, there is a decrease in availability of carbonate ions, in which reducing the of the water. (Talmage & Gobler, 2010, p ). Other negative effects of ocean acidification that have been seen are, but are not limited to, hinders in reproduction, decrease in respiration rate, metabolism shifts, changes in behavior, and increase mortality in general (Logan, 2010, p. 21). Larval shells of oysters have been shown to be strongly affected by increased CO 2 condition. In one experiment, the larvae in the high CO 2 conditions showed malformed shells, including convex hinges. 70% of CO 2 treated larvae kept in conditions with a of 7.4, were completely non-shelled or partially shelled and only 4% in that environment developed the normal D-shaped shells. Contrary to that, those kept in a controlled environment (not CO 2 treated), had a 70% success rate, with a majority of larvae having successful development (Kurihara, 200, p. 277). Other lab studies have shown that calcifying organisms have been seen to have a direct relation between the calcification rates and carbonate ion concentration. However, the impact varies among species; in few species even, it has been seen to enhance calcification due to acidification, but there is not prominent evidence of this (Logan, 2010, p. 21). Results from experiments like this are important because they lead to predictions that increased ocean will be the most important cause of larval mortality. This is because the

3 disruption of CaCO 3 affects the skeletogenesis process of forming the outer shell and size reduction of the organisms (Kurihara, 200, p. 27). Since this problem is becoming more noticeable in today s society, steps are starting to be taken to reduce the CO 2 emitted and then absorbed by the water, as well as reversing the effects that are already occurring. One of which, is that international climate control emission goals have been set, but with this approach, it does not specify which greenhouse gases matter in climate protection, but for ocean acidification CO 2, is the only relevant gas. Another technique is geoengineering; this is used by reducing the amount of incoming shortwave solar radiation or increasing the amount of long radiation (Logan, 2010, p. 24). Again, the problem with this is that this technique is more directed towards the global temperature rise rather than ocean acidification. Unlike these techniques, a natural, inexpensive technique should be used that targets directly the reduction of CO 2 in the ocean. One example of this is using autotrophs, because theoretically during photosynthesis, they take in CO 2 and then emit oxygen; which then could balance the. Some short-term experiments have resulted with specific sea grass demonstrating augmented photosynthetic rates and reduced light requirements and CO 2 generally doesn t limit photosynthesis in H 2 O (Logan, 2010, p. 21). Some phytoplankton species for example, have been shown to increase their photosynthesis rates by about 10% when CO 2 concentration is doubled (Logan, 2010, p. 21). One reason that phytoplankton would be a good resource, is that they are asexual single cell organism with rapid cell division. This makes them ideal for laboratory testing, as well as their evolutionary change is faster than other species. They are also the source of the global carbon fixation in the ocean (Collins, Rost, & Rynearson, 2013, p. 140) Three of the major planktonic CaCO 3 producers are coccolithophores, foraminifera and euthecosomatous petropods. All three export [a] flux of CaCO 3 ranging from the deep sea to the upper ocean (Fabry, Seibel, Feely, & Orr, 200, p. 417). When they are grown in seawater with the of 560 and 740 ppm, shell reduction in this calcifying species declined by 6-14% respectively compared to values equivalent to pre-industrial values. When one species of phytoplankton were observed under high light conditions, the surrounding that was tested increased as a result of CO 2 removal during symbiotic photosynthesis. Contrary, that same species tested, but grown in a dark environment, has less on and impact on the change of ocean

4 (Fabry, Seibel, Feely, & Orr, 200, p. 417). These three species are calcifying phytoplankton, but there are many other types of phytoplankton in the ocean. Two of the other main types of phytoplankton are nitrogen fixers (cyanobacteria) and silicifiers (diatoms) both having different effects under acidic conditions (Fabry, Seibel, Feely, & Orr, 200, p. 141). The species of Tetraselmis serve not only as phytoplankton in the ocean, but as a source of food and energy for many filter feeders including oysters. As seen in figure 1 they are a part of the Viridiplantae, Clorophytes. Two common species in the northeast, of Tetraselmis are, Tetraselmis sp PLATP and Tetraselmis chui (PLY429). Those species cells weights are*: SPECIES FILTER VOLUME TOTAL WEIGHT (mg) FILTER WEIGHT (mg) PLATP 501 5mL PLY mL Figure 1: * This information was provided by the scientists at NOAA SAMPLE WEIGHT (mg) Figure 1: Phylogenetic diversity of eukaryotes. The four major lineages of eukaryotic phytoplankton are highlighted in bold typeface (prasinophytes, coccolithophorids, diatoms and dinoflagellates). These lineages are deeply divergent, highlighting their potentially divergent responses to the effects of climate change. Branching order among some lineages is unresolved (dotted lines) The Authors. Evolutionary Applications published by John Wiley & Sons Ltd 7 (2014)

5 III. IV. Figure 2: Hypothesis: Both species of Tetraselmis will all increase the in the environment because in theory since there are autotrophs and undergo photosynthesis they should intake some of the CO 2 in the water and release O 2 regulating the water. I believe that the species PLY429 will do this at a faster rate than PLATP because it has a larger cell size, thus taking in more CO 2 releasing more O 2 during photosynthesis. Experimental Design: To create an ocean acidification environment, more tangible for research, and one that would simulate future ocean conditions, I will be using a CO 2 bubbler, and pump the CO 2 into a large jug and distribute into my bottles. This device will allow me to quickly create an acidic environment similar to one in the future (around 2100). My desired will be around , and once that is achieved I will distribute it into my and 0.5L bottles. I will be using SodaStream bottles for this experiment because they have a tight, rubber seal at the top because they are designed to keep the CO 2 in the bottles when making soda. I will take the and alkalinity at various times, once in the morning, and once at night, to see if there are any changes (see procedure). Then after results are collected from this experiment the phytoplankton vessel with the highest will then be used in the next experiment when there is the addition of oyster larvae. LEGEND BOTTLE NUMBER SPECIES BOTTLE SIZE START *AMBIENT = LOW= 7.24 V. Procedure: Figure 2 illustrates the design set up of the experiment described. 1. Gather materials

6 CO 2 Bubbler 6 empty 1 Liter SodaStream bottles 6 empty 0.5L bottles* About 10LOcean water 4mL per / 2.2mL per 0 of PLAT P** 2.7 ml per / 1.5 ml per 0 of PLY429** / alkalinity test kit (pool water test kit) Electronic meter for accuracy Pipets Distilled water for rinse 4 vials with Iodine crystals Light Source * To eliminate any headspace in the 0.5L SodaStream bottles and extra 0.05L was added to fill to the top **To determine the appropriate amount of phytoplankton to put in each container so that the amounts are equal, first the size of each phytoplankton must be calculated. PLATP = micrometers PLY429= 15 micrometers Then using a using a hemocytometer, both cells are counted using one milliliter. The target density in this experiment for both species was 1 x 10 4 cells per milliliter or 1 x 10 7 cells per liter. After counting the cells: PLATP = 2.5 x 10 6 cells per milliliter PLY429= 3.7 x 10 6 cells per milliliter After finding each cell density, divide the target cell density by the density s just found for each species, and that will equal the amount of each species to use per liter and multiply by 0.55 to equal the amount to use for the smaller container. 2. Determine the starting of the ocean water and add to all bottles labeled AMBIENT 3. Then with the remaining water pump CO 2 into the container until desired is achieved ( ) then distribute into all bottles labeled LOW

7 4. Then add the designated amount of each phytoplankton species to the bottles as shown in Figure 2 5. Leave 4 bottles without any phytoplankton for control 6. Mix all containers 7. During each time of observations record and alkalinity following the instructions of the kit being used. When doing each test take a sample using a pipet from each container and store in a vial with Iodine crystals to save for cell counts when the experiment is finished. Iodine crystals are used to kill the living cells, stain them, without disrupting the to get an accurate cell count. 9. Observe and record observations in the data table When observing take a sample in the morning, after the sample is in the dark all 10. Graph results 11. Conclude night, and at night, after the sample is in the light all day, to track changes.

8 VI. Data Table BOTTLE NUMBER T=0 12:00pm 11/14 T=1 :00am 11/15 T=2 6:00pm 11/15 T=3 5:00am 11/1 T=4 7:00pm 11/1 T=5 10:00am 12/1 1 PLY429 2 PLY429 3 PLY429 4 PLY429 5 PLATP 6 PLATP 7 PLATP PLATP CONTROL

9 VII. Variables Independent Variable: Type of phytoplankton tested PLATP PLY429 Size of container Dependent Variable: Acid Concentration ( change) Alkalinity Control: Container of both size with no phytoplankton low and high Constant: Amount of phytoplankton Light intensity Location Starting Amount of water

10 VIII. Results BOTTLE NUMBER T=0 12:00pm 11/14 T=1 :00am 11/15 T=2 6:00pm 11/15 T=3 5:00am 11/1 T=4 7:00pm 11/1 T=5 10:00am 12/1 1 PLY Salinity- 29ppt Alkalinity Alkalinity PLY Salinity- 29ppt Alkalinity Alkalinity Alkalinity Alkalinity PLY Alkalinity Alkalinity Alkalinity Alkalinity PLY Alkalinity Salinity- 29ppt Alkalinity Alkalinity PLATP Salinity- 29ppt Alkalinity PLATP Salinity- 29ppt Alkalinity Alkalinity PLATP Salinity- 29ppt Alkalinity Alkalinity Alkalinity Alkalinity PLATP Salinity- 29ppt Alkalinity Alkalinity Alkalinity Alkalinity CONTROL Salinity- 29ppt Alkalinity Alkalinity- 140 Salinity- 29ppt Alkalinity

11 Alkalinity- 150 Salinity- 29ppt Alkalinity- 150 Salinity- 29ppt Alkalinity Alkalinity Alkalinity Flow Cytometer This set of data shows cell count from my final sampling day, time 5. Bottle Number Count Volume (µl) Count per µl Count per ml The pictures above, from the flow cytometer, are a visual representation of the samples taken from bottles 3 and 6 respectively.

12 IX. Graphs Graph 1 BOTTLE SIZE VS PH These graphs represent the relationship between bottle size and organized by container size and starting. BOTTLE SIZE VS PH PLATP AMBIENT PLAT P 6 PLAT P Linear (5 PLAT P ) Linear (6 PLAT P ) Graph BOTTLE SIZE VS PH PLATP LOW 7 PLAT P PLAT P Linear (7 PLAT P ) Linear ( PLAT P)

13 Graph BOTTLE SIZE VS PH PLY429 AMBIENT 1 PLY429 2 PLY429 Linear (1 PLY429 ) Linear (2 PLY429 ) Graph BOTTLE SIZE VS PH PLY429 LOW 3 PLY429 4 PLY429 Linear (3 PLY429 ) Linear (4 PLY429 )

14 SPECIES VS PH Graph 5 These graphs represent the comparison between the two species organized by starting value and bottle size. PLATP VS PLY429 Ambient PLY429 5 PLAT P Linear (1 PLY429 ) Linear (5 PLAT P ) Graph PLATP VS PLY429 Low 3 PLY429 7 PLAT P Linear (3 PLY429 ) Linear (7 PLAT P )

15 Graph 7 PLATP VS PLY429 Ambient PLY429 6 PLAT P Linear (2 PLY429 ) Linear (6 PLAT P) Graph PLATP VS PLY429 Low Time 4 PLY429 PLAT P.55 L Linear (4 PLY429 ) Linear ( PLAT P.55 L)

16 ALKALINITY Graph 9 This graph represents the alkalinity trend of all the bottles from T=0 to T=5 ALKALINITY (kh) Alkalinity per BoVle Trend CONTROL Graph 10 This graph represents the change of all the control bottles. CONTROL TREND AMBIENT AMBIENT LOW LOW

17 COMPARE TO CONTROL Graph 11 These graph represent the comparison of the low and ambient environment to the control of the same environment. These graphs are separated by species and bottle size. Control vs Experimental (PLY429 ) PLY429 3 PLY429 9 AMBIENT 11 LOW Graph Control vs Experimental (PLY429.5L) 2 PLY429 4 PLY AMBIENT 12 LOW

18 Graph 13 Control vs Experimental (PLATP ) PLAT P 7 PLAT P 9 AMBIENT 11 LOW Graph Control vs Experimental (PLATP.5L) 6 PLAT P PLAT P 10 AMBIENT 12 LOW

19 X. Experiment Analysis Overall this experiment that I created went as a planned, but some minor problems were able to be resolved. The first problem I encountered was the base of my experiment, the phytoplankton. Unsure of where to get the phytoplankton, I went to Dr. Malinowski, a local oyster grower to start, since he feeds his oyster s phytoplankton. He suggested I contact the scientist at NOAA in Milford CT. When I went down to their labs, not only was I able to get the two species of phytoplankton I was looking for, but I learn various new lab skills, that helped me further develop my experiment. The quality of my experiment would not have been the same without them. Originally, I planned to use my SodaStream to pump the CO 2 into the water, but I figured out that if I were to do that it would pump in too much at one time, resulting in a too low of to use. Instead, at the NOAA lab they have a special pump to add CO 2 to the water, which was much more efficient to use in order to get my desired. One of the many the new skills I learned was how to use a hemocytometer to count my cells. The idea was, that initially I needed to count the phytoplankton cells in order to get equal densities of each to start, so I would not have an extra variable on top of my others. I was able to do this because the original sample of phytoplankton was so dense with cells. Then I added the small sample of phytoplankton to my water, which made the phytoplankton very dilute and not even very noticeable to the eye. My plan was, every time I did my tests on the samples, I would save a small amount in a vial, and then go back to the lab to count them, to then see if one species had more cell division than another, or if the had an effect on it. I saved my samples without a problem, in a vial with iodine crystals at the bottom for preservation; but when I returned to the lab the samples were too dilute still to be able to count accurately. Instead, I could infer just by observing my bottles that the bottles with PLATP, had a higher cell density than the PLY429, I could tell this based on the color. The bottles with PLATP were a darker shade of green compared to the PLY429. I did not originally plan on testing anything other than, because I was planning to do another experiment using oyster larvae, but due to time constraints and logistics I was unable to do that. To make up for that I tested to see if the alkalinity of the water changed. To test this I just used the same test kit as for the. This helped me add more than just as a result for my experiment.

20 XI. Without the help from the scientist at NOAA my experiment would not have been able to turn out the way it did. I am especially grateful for their help, I know they took time out of their own day to help me, which was very generous of them, and I cannot thank them enough. Conclusion Based on my results I can conclude that the addition of both species of phytoplankton did in fact increase the of the water in ambient and low environment. Not only did they increase the in both environments, but did so also in the large and smaller sized containers. When interpreting my results it is important to keep in mind that is a logarithmic scale, where even just a change from a of 4 to a of 5 is a very large difference. Comparing bottle size to the of each species, graphs 1-4, it can be seen that in the low environment that both species had a significantly greater trend line in the 0.5L bottles compared to the bottle. As for the change in the ambient environment, there was not as a dramatic difference between the 0.5L bottle and the bottle. Comparing the two species to change which can been in graphs 5-, my graphs are separated by bottle size and starting environment either low or high. These graphs show that in ambient environments in both bottle sizes that PLATP had a more significant compared to the PLY249. In the low environments of both species, there was not a significant enough amount of change between the two species to draw any conclusions. Lastly, in graph 9, which shows the alkalinity trends, it shows that there was not very much variation of alkalinity change thought out the bottles and throughout each time being tested. The lowest alkalinity reading was 1300KH and the highest reading being 1500KH. Graphs show the comparison of the of my experimental bottles compared to my control bottles. The of my control bottles stayed relatively the same while the experimental bottles all increased in thus proving that phytoplankton do increase the of the water. I can be noticed on my graphs that between time 4 and 5 there is the greatest amount of change. I have concluded that this is because between those two time, was the most time passes between testing periods, as well as the most time the bottles had in sunlight. During my experiment two days were cloudy and raining, so my bottles did not get much sun. This is important because to undergo photosynthesis the phytoplankton need sunlight, thus the more sunlight the more efficiently they will photosynthesize. Another reason for the dramatic spike

21 XII. was that I did my last tests at the NOAA lab and had access to more precise measuring tools, which gave me a very accurate reading. Overall I have disproved my hypothesis being that the PLY429 will increase the faster than PLATP based on cell size. I believe based on my data and information no collected that it was the opposite that occurred. The PLATP increased at a faster rate in terms of bottle size, comparison of species to species, as well as comparison to the control. The main reason I believe that this occurred was because since PLATP has a smaller cell size it was then able to reproduce at a faster rate, thus resulting in more cells that photosynthesize. I do not have quantitative data to verify this because my samples were still very diluted, and the reading from the flow cytometer were only from 1ml of my solution and may not accurately be showing the true cell counts. Qualitatively, I could see based on color inside my bottles that the PLATP bottles were a much darker denser green than the PLY429, which I believe is due to more cells. Extension If I were to do an extension from this experiment, there are various other experiments I could test using different variables based off the results of this experiment. First I could test different start concentrations of the phytoplankton will be tested to see if the amount of phytoplankton has any effect on changing the or alkalinity. Another variable that could be tested, is light intensity because phytoplankton are photosynthetic and require sunlight, I could test in different light intensity to simulate the light in different depth in the ocean. For example a bottle stored in the dark would represent the deep ocean, while the more light there is the high up in the ocean it would represent. Lastly since ocean acidification has a larger negative affect on calcifying organism, based on these results it could be tested to see if the addition of phytoplankton will reverse the detrimental effect that ocean acidification has on the shells of these organism. These results could result in a decrease of mortality of calcifying organisms, such as oysters, because there shells are vital to their survival. The results from this experiment help lead to more experiments to find a solution to a global problem.

22 References: Collins, S. e., Rost, B., & Rynearson, T. A. (2013). Evolutionary Potential of Marine Phytoplankton under Ocean Acidification. Evolutionary Applications, Fabry, V. J., Seibel, B. A., Feely, R. A., & Orr, J. C. (200, 15 Febuary). Impacts of ocean acidification on marine fauna and and ecosystem processes. ICES Journal of Marine Science, 65(3), Retrieved October 19, 2014, from Kurihara, H. (200, December 23). Effects of CO2-driven ocean acidification on the early developmental stages of invertebrates. Marine Ecology Progress Series, 373, Logan, C. A. (2010, November). A Review on Ocean Acidification and America's Response. Bioscience, 60(10), Retrieved September 9, 2014, from Talmage, S. C., & Gobler, C. J. (2010, October 5). Effects of past, present, and future ocean carbon dioxide concentraion on the growth and survival of larval shellfish. Preceedings of the National Acadmeny of Sciences of the United States of America, 107(40), Retrieved September 19, 2014, from