Month: June 2023

By: Madison Malloy

Ocean acidification is the process of the ocean becoming more acidic (as the name implies), and is caused by an increase in CO2 (carbon dioxide) in the atmosphere and ocean. CO2 concentration has been on the rise in the atmosphere for the past 200 years as we progressively began to emit more greenhouse gases (National Oceanic and Atmospheric Administration [NOAA], 2012). A large increase in CO2 in the atmosphere can not only have a warming effect in the atmosphere, but in turn can also allow more carbon dioxide to be absorbed into the ocean. It is estimated that around one-third of the CO2 produced in the atmosphere is absorbed by the ocean (IAEA 2022). When too much is absorbed, it can have adverse impacts on organisms, as well as on how the ocean functions as a whole.

Many organisms rely on calcium carbonate to build their shells (IAEA, 2022)

When CO2 is absorbed, a series of reactions take place that result in fewer carbonate ions in the ocean. Carbonate ions are pretty cool to have around, as they help to make up protective parts of many important organisms in the ocean, including shellfish, coral, and Echinoderms. When there is more CO2 is being absorbed and less carbonate in the ocean, the calcifiers (organisms that use calcium carbonate to build parts of their bodies) have less stuff available to use. This can be harmful to them, the ocean, and people, as they play a vital role in ecosystems and the livelihoods of coastal communities.

Fishing boats on the Bay of Fundy (Saltscapes Magazine, n.d.)

Ocean acidification can have a large impact on people that rely on the ocean. It has been estimated that 3 billion people worldwide have livelihoods that depend on the ocean, and we must also take into account the cultural traditions that have depended on the ocean for generations (IAEA, 2022).

Sea stars on the sea floor (Journal of Young Investigators, 2017)

One group of organisms that may be greatly impacted by ocean acidification are Echinoderms, which include sea stars and sea urchins. Here in St. Andrews, you can find sea stars and sea urchins hanging out at the wharf and in the intertidal zone every day! Sea stars and sea urchins need calcium carbonate to make up various parts, and with less available carbonate in the ocean, they may be more vulnerable to predators, as well as have a harder time feeding and moving (Seattle Aquarium, n.d.). Negative impacts on shellfish can also be observed, with the acidic seawater capable of deteriorating the shells of the young of some species before they can fully form (NOAA, n.d.). This can present challenges for the livelihoods and diets of coastal Indigenous communities that rely on shellfish and other calcifiers as a large portion of their diet (UW News, n.d.)

Purple sea urchins (Jeremy Glass, 2017)

Despite how grim it may seem, there are efforts happening locally and internationally to address the issues of ocean acidification and climate change. As a method to track the changing ocean conditions, Indigenous-led monitoring and management is essential to understanding the impacts on ecosystems and coastal communities (Oceans North, n.d.). Various studies are also underway to explore ways that organisms are adapting, as well as information that can inform policy changes on a larger scale.

A recent study suggests that protecting important habitats like mangroves and seagrass can improve the alkalinity of the surrounding water on a local scale by absorbing more CO2 out of the atmosphere (Nature News, 2023). A different study found that a calcareous sponge, Paraleucilla magna, was able to make its skeleton under very acidic conditions, which may be promising for its ability to adapt should acidification progress (Nature News, 2023). Although these are only a few examples, there are countless studies that have been completed or are underway that aim to learn more about the impacts of this issue. In the face of climate change and ocean acidification, solutions that involve and value the knowledge of coastal communities and Indigenous communities are essential in addition to knowledge derived from scientific research.

References

Fakhraee, M., Planavsky, N. J., & Reinhard, C. T. (2023, May 29). Ocean alkalinity enhancement through restoration of Blue Carbon Ecosystems. Nature News. https://www.nature.com/articles/s41893-023-01128-2

Glass, J. (2019, October 18). Sea urchins are the edible pincushions of the Ocean. HowStuffWorks. https://animals.howstuffworks.com/marine-life/sea-urchin.htm

Hawkins, C. N., & Pain, C. S. (n.d.). Oceans and climate. Oceans North. https://www.oceansnorth.org/en/what-we-do/oceans-and-climate/

IAEA. (2022, December 15). How carbon emissions acidify our ocean. IAEA. https://www.iaea.org/bulletin/how-carbon-emissions-acidify-our-ocean

NOAA. (n.d.) Ocean Acidification’s impact on oysters and other shellfish. https://www.pmel.noaa.gov/co2/story/Ocean+Acidification%27s+impact+on+oysters+and+other+shellfish

Ocean acidification and sea urchins. Seattle Aquarium. (n.d.). https://www.seattleaquarium.org/blog/ocean-acidification-and-sea-urchins#:~:text=Ocean%20acidification%20could%20interfere%20with,and%20crabs%20and%20other%20crustaceans

Officer, C. T. (2017, September 30). Threat of ocean acidification to echinoderms. Journal of Young Investigators. https://www.jyi.org/2010-november/2011/11/28/threat-of-ocean-acidification-to-echinoderms

Partnering with indigenous communities to anticipate and adapt to Ocean Change. UW News. (n.d.). https://www.washington.edu/news/2018/03/21/partnering-with-indigenous-communities-to-anticipate-and-adapt-to-ocean-change/

Ribeiro, B., Lima, C., Pereira, S. E., Peixoto, R., & Klautau, M. (2023, April 25). Calcareous sponges can synthesize their skeleton under short-term ocean acidification. Nature News. https://www.nature.com/articles/s41598-023-33611-3

US Department of Commerce, N. O. and A. A. (2012, August 1). What is ocean acidification?. NOAA’s National Ocean Service. https://oceanservice.noaa.gov/facts/acidification.html

Wallace, J. (n.d.). The unmatched tides of fundy. Saltscapes Magazine. https://www.saltscapes.com/food-travel-guide/stories/2954-the-unmatched-tides-of-fundy.html

By: Madison Malloy

Sitting at the base of the Bay of Fundy, St. Andrews is no stranger to large tides. The Bay of Fundy sees tides up to 16 metres high, and here in St. Andrews, our tides can rise as high as 8.5 metres (Government of Canada, 2023)! In order to appreciate what causes this phenomenon, we must understand how the Sun and Moon influence tides, as well as the special characteristics of the Bay of Fundy.

How frequent are tides? (National Oceanic and Atmospheric Administration [NOAA], 2013)

The largest tidal force is the gravitational pull of the Moon on the Earth, which pulls the water towards the Moon, forming a bulge. On the other side of the earth, a bulge of approximately equal size is formed from inertia, the opposing force to gravity (NOAA, 2005). In the image above, this is represented by the high tides on either side of the equator, and low tides at both of the poles.

We must also consider the secondary tidal force of the Sun on the Earth. Despite the Sun being around 400 times bigger than the Moon, it has a lesser impact on the tides because it is much, much farther away (Britannica, n.d). The gravitational pull from the Sun creates a smaller bulge in addition to the one from the Moon. Instead of thinking of the tides as going up and down, you can think of the Earth as rotating in and out of these stationary bulges every day.

Spring vs. neap tides (Bay of Fundy, n.d)

Have you ever wondered why the phase of the Moon impacts how high the tides are? It comes down to the position of the Moon relative to the Sun. As seen above, when the Moon, Sun, and Earth are in line, a full or new Moon is observed, and the bulges from the Sun and Moon amplify to make the highest tidal range. This is known as a spring tide, and these are seen twice each lunar month (NOAA, 2014). Also twice each lunar month are neap tides, which happen when the Sun and Moon are perpendicular to each other. This causes the bulges to have a dampening impact, resulting in the lowest tidal range.

Why does the timing of the tides change every day?

First, we need to think about how the Earth rotates once every 24 hours and the Moon rotates around the Earth once every 28 days. Because both the Earth and Moon are rotating, the Earth needs to move a bit extra, around 50 minutes every day, in order to catch up to the Moon. This means that in places with only one high tide a day (diurnal tides), like the poles, the tides come every 24 hours and 50 minutes instead of every 24 hours. Here in St. Andrews, we get two approximately equal-sized tides every day (semidiurnal tides) which come every 12 hours and 26 minutes.

The difference between high tide and low tide outside of the Jolly Breeze Whale Adventures office, St. Andrews

In The Bay of Fundy, home to the highest tides in the world, there are two main features that influence its size. The first factor, the shape of the bay, allows the water to be funneled up and down, creating high tidal levels. Tidal resonance, the process of water being flushed in and out of the bay at perfect timing, allows incoming water to be pushed to high levels. These two factors result in breathtaking tides. We get lower tides at the base of the Bay of Fundy than at the head of the bay, but tides an average of 5 metres high can still be observed here, which tower over the global average of 1 metre (Time and Date, n.d).

Whether you come to St. Andrews for the tides, whales, or lobster rolls, one thing goes without question: St. Andrews would not be the same without the powerful influence of the tides.

References

Encyclopædia Britannica, inc. (n.d.). Understand the relative size of the Sun, the Moon, and other Solar System objects. Encyclopædia Britannica. Understand the relative size of the Sun, the Moon, and other solar system objects

Parks Canada Agency, G. of C. (2023, March 17). Tides in Fundy National Park. Fundy National Park. Tides in Fundy National Park

Spring vs. Neap Tides. Bay of Fundy. (n.d.). Spring vs. Neap Tides – Bay of Fundy

US Department of Commerce, N. O. and A. A. (2005, December 1). Tides and water levels, gravity, inertia, and the two bulges, nos education offering. Gravity, Inertia, and the Two Bulges – Tides and water levels: NOAA’s National Ocean Service Education. Gravity, Inertia, and the Two Bulges – Tides and water levels: NOAA’s National Ocean Service Education

US Department of Commerce, N. O. and A. A. (2013, June 1). How frequent are tides?. NOAA’s National Ocean Service. How frequent are tides?

US Department of Commerce, N. O. and A. A. (2014, August 1). Why do we have spring tides in the fall?. NOAA’s National Ocean Service. What are spring and neap tides?

What causes ocean tides?. The Moon Causes Tides on Earth. (n.d.). What Causes Tides? – Moon