Acidification Tolerance of Aquatic Organisms Elana Sanford, Joey Uy, Sona Trika, Michelle Hines Cluster 3: Living Oceans and Global Climate Change UCSD COSMOS 2013 Dr. Ngai Lai Introduction The ocean is an interconnected ecosystem: everything is bound together and the entire system can be influenced by any factor. The ocean has always been slightly basic; however, this is gradually changing. Every year CO2 impacts increase due to anthropogenic emissions such as electricity and transportation pollution. According to National Geographic’s journalist Claire Christian, “The ocean has already become about 30% more acidic (a drop of 0.1 pH units) since pre-industrial times,” (Christian, 2013). This abundance of CO2 negatively affects the livelihood of all of its inhabitants. The excess of CO2 in the atmosphere reacts with the ocean to create carbonic acid (H2CO3) and therefore lowering the pH of the ocean. These carbonic dioxide emissions are not the only source of acidification: acid rain also acidifies freshwater ecosystems. In Franklin, New York there is a body of water known as “Little Echo Pond” that has a pH of 4.2. The cause of this extremely acidified pond is chalked up to acid rain, according to the EPA (“Acid Rain.”, 2013). Both plants and animals are subject to higher mortality rates when exposed to a lower pH. Organisms’ bodily functions are affected and organic material is often found to decay. In this study, we will examine the impact of acidification on organisms using the condition as in the pond in Franklin, New York. Our hypothesis is that acidification will affect the viability of living organisms. Conclusion & Applications Abstract Ocean acidification is the occurrence of decreasing pH in Earth’s oceans. The seas’ pH has been continuously decreasing due to anthropogenic effects and the constant emission of carbon dioxide in the atmosphere. This has forced marine organisms, ranging from plants to animals, to either adapt or perish. Knowing this, we decided to examine the extent of the effect of acidification on aquatic life by observing the effect on six species: brine shrimp (Artemia), and duckweed (Lemna spp.), sea snails (Tegula funebralis), blackworms (Lumbriculus variegatus), ghost shrimp (Palaemonetes paludosus), and guppies (Poecilia reticulata). The successes of the animals’ ability to survive the acidic conditions varied greatly with the species yet there remained a general trend of increasingly acidic conditions having an increasingly negative effect on the experimental subjects, demonstrating the possibly disastrous impacts of acid rain and ocean acidification. Methods Brine Shrimp 1. Set up 2 one liter flasks with the same amount of water in each (note volume). One flask was supplied with a regular stream of air bubbles while the other put has a stream of bubbling CO2. 2. Salt were added to both flasks as a medium for brine shrimp eggs to hatch. 3. Number of eggs were estimated and recorded from 1 mL of homogenous sample. 4. Allow eggs to incubate for 72 hours with aeration and heat. 5. Following that 1 mL of 8 samples from each flasks were sampled to assess the number of hatched Artemia and unhatched cysts Blackworm 1. Three petri dishes were filled with 50 mL of the following freshwater solutions: 1) pH 7, 2) pH 4.5, and 3) pH 4.1. 2. 10 worms were placed in each dish. Record viability at the end of 15 minutes. Duckweed 1. Three petri dishes were filled with 100 mL of the following freshwater solutions: 1) pH 7, 2) pH 3.2 , and 3) pH 2.8. 2. 50 sprouts of duckweed were added to each dish and viability were assessed 72 hours later. Guppy and Ghost Shrimp 1. At guppy and shrimp were added to a 75 mL container of freshwater at 1) pH 7, 2) pH 4.5, and 3) ph 4.1. 2. After 15 minutes, the animals were assessed. Sea Snail 1. 1. Add 50 mL of solution to a dish with pH 7, 4.1 and 4.5 and placed a snail in the center of the dish. 2. Mobility were recorded after a hour of treatment. Statistical Analysis Data are reported as mean±sem. One-way ANOVA was used to determine differences among groups. P<0.05 is considered significant. Acknowledgements Our group is very appreciative of the help that we received in tabulating our data and experimental design from Dr. Lai. Chase Hightower was also a great help when conducting these experiments. The entire cluster three group was also very helpful with their counting of organisms. Special thanks to Ms. Megan Jones for helping with the creation of this poster. Figure 1. Above: Sea snails, collected in a intertidal zone in La Jolla, California and used in this collection of experiments. Figure 2. Above: Lemnoideae, also known as duckweed sprouts, used in this collection of experiments. Figure 5. Right: An example of blackworms (“Betta Care.”, 2013). Figure 3. Above: A sample of Artemia, also known as brine shrimp, used in this collection of experiments (Warren, 2013). Figure 4. Left: Experimental set up for ghost shrimp and guppy experiments. Data & Observations Blackworm Sea Snail Duckweed Guppies Ghost Shrimp Analysis Over the course of a month in conducting these experiments on the various aquatic organisms, our data showed similar dire responses in terms of tolerance towards acidification. For instance, the brine shrimp eggs failed to hatch under acidic condition induced by a constant stream of carbon dioxide. On the other hand, about one third of the population hatched in ambient condition. Most of the black worms perished under acidic condition with a survival rate of 10% at pH 4.5 and 0% at pH 4.1. Black worms are highly important deposit feeders that help with the further breakdown of larger food materials as well as aerating the benthic for the microbes. Conversely, some of the organisms were able to withstand the insult impose on them. For example, the sea snails were able to overcome the harsh acidic conditions by closing its operculum. Their survival rate is 100% at the end of our observational period. However, we predict that extending the experimental period will likely cause the snail to move in the acidic condition. These are grazers that feed on plant materials but if the food source were to reduce these snails will demise. Interestingly, duckweed had the strongest defense against the acidic medium largely in part of their rigid cell walls. We found that after 72 hours at even a lower pH of 3.2, the viability was 72%, which is paradoxically similar to those in freshwater (69%). However, at pH 2.8 none of the duckweed survived. Guppies were also an example of this intolerance: 0% of the guppies in the most acidic conditions (pH 4.5) survived when exposed to a short period of time, while they managed to persist in the freshwater and at pH 4.1 for 1 hour and fifteen minute. The ghost shrimp were a hardier species with no mortality in all conditions. Different species respond to low levels of pH differently: some of the test subjects were highly vulnerable when exposed to high pH, whereas some can tolerated the conditions within our observational period. For instance, Lumbriculus variegatus (black worms) were highly vulnerable to a drop in pH and perished almost immediately. The sea snails, on the other hand, were more tolerant of the environment largely due to their thick covering that are designed to withstand the harsh intertidal conditions. This study provides insights into how various aquatic organisms react to an imposing threat. Those with thinner integument will succumb to the threat while those with thicker integument or mobility can evade the danger. For instance, Lemnoideae (duckweed) is a major producer for various organisms, providing nutrients and protection that are key necessities for survival. Lemnoideae is a main food source for many birds and fish, and supplies shelter for aquatic animals such as frogs, fish, crustaceans, etc. If acid rain was to affect an ecosystem with these plants they would devastate the duckweed population, as demonstrated in our data, and negatively impact the welfare of the various species dependent on these plants. In the case of, An ecosystem without Lumbriculus variegatus (blackworms) would be missing they very important decomposers that allow both lands to be fertile and feed other creatures. All of the species in this experiment can be related to blackworms and duckweed: each experimental specimen used in these experiments has a large amount of other species depending on it. Each of these species would perish and cause an entire ecosystem to suffer tremendously if their environment was adulterated by acid. When conducting these experiments errors occasionally arose. For instance, during the duckweed experiment, there were several sources of human error that may have impacted the overall data. When other colleagues were counting the amount of duckweed, they were confused with whether to classify a sprout as alive or dead. This issue was addressed by conducting another count to ensure that the numbers were consistent. In the sea snail experiment, the snails were immersed in water that did not contain salt and therefore their behavior may have varied from what would occur in a more natural environment. In the case of the brine shrimp experiment, running the CO2 line for an extended period does not demonstrate a case that is extremely comparable to nature. The very low pH likely caused more extreme results than would be expected with a less extreme case; in fact, it is quite possible that nearly no organisms could survive such extreme conditions. In the ghost shrimp and guppy experiment, alternative results may have arisen from a larger containment area where the animals could be more mobile. Despite these possible areas of uncertainty, these results are relevant to today's world of acidifying bodies of water. Understanding individual species' responses to acid conditions will allow scientists to understand the effect of ocean acidification and acidic pollution on a broader scale. Further experiments testing entire ecosystems will further augment the understanding the world’s acidifying waters. Sources Christian, Claire. "Strong Evidence for Ocean Acidification Impacts in Southern Ocean."National Geographic. National Geographic Society, 29 Nov. 2012. Web. 18 July 2013. <http:/newswatch.nationalgeographic.com/2012/11/29/strong-evidencefor-ocean-acidification-impacts-in-southern-ocean/>. Warren. "Brine Shrimp (Artemia Salina) Eggs with Hatched and Hatching Nauplius Larvae." Warren Photographic. N.p., n.d. Web. 30 July 2013. <http://www.warrenphotographic.co.uk/04852-brine-shrimp-eggshatching>. "Acid Rain." Lake Scientist. N.p., n.d. Web. 31 July 2013. <http://www.lakescientist.com/learn-about-lakes/water-quality/acidrain.html>. "Betta Care." Betta Care. Vangbettas.com, n.d. Web. 01 Aug. 2013. <http://www.vangbettas.com/betta_care.htm>.