Acidification Tolerance of Aquatic Organisms
Elana Sanford, Joey Uy, Sona Trika, Michelle Hines
Cluster 3: Living Oceans and Global Climate Change
Dr. Ngai Lai
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
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
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
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
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.
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.
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
Figure 5. Right:
An example of
Figure 3. Above: A sample of Artemia,
also known as brine shrimp, used in this
collection of experiments (Warren,
Experimental set up
for ghost shrimp
Data & Observations
Sea Snail
Ghost Shrimp
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.
Christian, Claire. "Strong Evidence for Ocean Acidification Impacts in
Southern Ocean."National Geographic. National Geographic Society, 29
Nov. 2012. Web. 18 July 2013.
Warren. "Brine Shrimp (Artemia Salina) Eggs with Hatched and Hatching
Nauplius Larvae." Warren Photographic. N.p., n.d. Web. 30 July 2013.
"Acid Rain." Lake Scientist. N.p., n.d. Web. 31 July 2013.
"Betta Care." Betta Care., n.d. Web. 01 Aug. 2013.

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