Tag Archives: Phytoplankton

What Can You Find in a Drop of Sea Water?

The ocean is vast! It covers 70% of the Earth and is home to the largest animal ever to have lived on our planet- the blue whale. It’s easy to get caught up in the majesty of the ocean’s magnitude, but have you ever thought about what you can find in just a single drop of seawater?

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Let’s zoom in and take a look! Left: phytoplankton, right: assorted zooplankton There’s a whole other world living on this microscopic level! When you go for a swim in the ocean, these little guys are floating all around you. According to the Australian Department of Environment and Energy, a single liter of ocean water contains around a million phytoplankton, half a million zooplankton, a billion bacteria and four billion viruses! Never heard of phytoplankton or zooplankton? Let’s learn a bit more about them and why they are so important.

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Assorted diatoms Phytoplankton are the basis of the oceanic food web. They are tiny, planktonic (free drifting) organisms that use photosynthesis to convert sunlight into energy. They contribute over half of the world’s oxygen through photosynthesis! Pollution (pesticides, oil, heavy metals, etc.) can be extremely harmful to phytoplankton- and when they take a hit from our harmful waste- entire oceanic communities are damaged.

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Krill Microscopic zooplankton are actually miniscule animals. Some zooplankton will grow out of this planktonic stage of life, but others will always remain tiny drifters. Zooplankton feed on phytoplankton, bacteria and other zooplankton. Although zooplankton are small, some of the ocean’s biggest animals dine on them. Remember the blue whale- the largest animal to have ever lived on planet Earth? They subsist entirely on zooplankton (mainly krill and copepods- the zooplankton that the character Plankton from Spongebob was based off of). Want another reason to marvel at these critters? Many of these organisms, namely a group of phytoplankton called dinoflagellates, are bioluminescent, which means they can produce their own light and glow in the dark! Dinoflagellate bioluminescence Keep microscopic, oceanic plankton happy by keeping our oceans clean! And don’t forget about the millions of organisms floating around you next time you take a swim!

Check out these links if you want to learn more:

Bioluminescence: https://askabiologist.asu.edu/glow-dark-plankton Importance of plankton: http://www.st.nmfs.noaa.gov/copepod/about/what-n-why.html
TedEd plankton video: https://www.youtube.com/watch?v=xFQ_fO2D7f0
Harmful algal blooms: https://oceanservice.noaa.gov/facts/why_habs.html

Written By: Talia Niederman

sea water reference

Diatomaceous Earth

All of you know what earth is. Many of you know what phytoplankton are. Some of you know what a diatom is. But what in the world is diatomaceous earth?! First, let’s define what the “diatom” in diatomaceous earth means: diatoms are microscopic phytoplankton, which are incredibly common in all bodies of water. This plankton has been an important part of the food chain and the earth for millions of years! When prehistoric diatoms would die, they would fall to the bottom of their habitats, be it rivers, lakes, oceans, or ponds. Diatom cell walls are made up of silica, and after millions of years of these little guys stacking up on each other, they formed white, chalky, silica deposits that we call diatomaceous earth.

Diatomaceous Earth

On Catalina Island, we have these silica deposits located in some of our trails! In fact, if you have ever hiked our shrine loop, you can see some right from the trail. To look for diatomaceous earth, just look for white rock that is chalky and crumbly. This means that the land that you are hiking on was once underwater and surrounded by tiny phytoplankton! Whoa!

Now that we know what diatomaceous earth looks like, let’s learn about some of its uses. Scientifically speaking, it is amazing evidence that many islands came from the ocean and is a great indicator of how productive and nutrient-rich the oceans were at the time that these islands were formed. Today, humans have found a multitude of uses for this algae-turned-stone. One popular use is as an alternative to pesticides to kill insect pests. Diatomaceous earth can be easily ground into a powder and used to dehydrate insects as it can soak up moisture and oils from the insects’ exoskeletons. Furthermore, we use it many beauty products such as face washes and toothpaste as it is abrasive and can gently scrape off dead skin and plaque. Amazingly, this ancient algae chalk is edible! Farmers feed food-quality diatomaceous earth to their cows and other animals to combat parasites. We can eat this stuff as well. In fact many bakers put it in their bread, as it helps to preserve the grain. Many believe that this stuff makes you live a longer life by cleansing your colon and ridding you of parasites too!

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All in all, diatomaceous earth is quite an incredible mineral. Millions of years ago this earthen material used to be alive and well, floating and producing oxygen in all the earth’s waters. Then when they died, they stacked up on each other and were transformed into an edible, bug killing, life lengthening rock that we can see on Catalina Island… how cool?!

For more:


Bioaccumulation and Biomagnification: Increasingly Concentrated Problems!

Bioaccumulation and biomagnification are two different processes that often occur in tandem with one another. Bioaccumulation is the process by which toxins enter the food web by building up in individual organisms, while biomagnification is the process by which toxins are passed from one trophic level to the next (and thereby increase in concentration) within a food web.

Photo credit: www.mercurypolicy.scripts.mit.edu

Synthetic (man-made) chemicals called Persistent Organic Pollutants, or POPs, are of primary concern when looking at bioaccumulation and biomagnification. These chemicals do not easily break down in the environment and can build up in the fatty tissues of living organisms. Some examples of POPs you may have heard of include DDT (an insecticide that was used extensively post-WWII) and PCBs (flame retardants). Although the production of these chemicals was banned during the 1970s and 1980s, they can still be found in the oceans as well as the tissues of many marine animals because of their ability to (1.) persist in the environment for long periods of time, (2.) move within water, and (3.) dissolve into the fatty tissues of living organisms. For all of these reasons, POPs like DDT and PCBs are especially good at bioaccumulating and biomagnifying.

Bioaccumulation occurs at the base of a food web, usually within primary producers like phytoplankton. These microscopic photosynthetic organisms absorb POPs directly from the seawater and accumulate them in their bodies over time. The toxins build up in their tissues because they are absorbed from the water at a rate faster than they can be metabolized.

Biomagnification occurs when slightly larger organisms called zooplankton feed upon the contaminated phytoplankton and in turn absorb POPs into their own tissues at a higher concentration. The more contaminated phytoplankton a zooplankton eats, the more pollutants it will have in its body. In other words, the POPs can be passed from producer to consumer (to consumer, to consumer, and so on…) Biomagnification can continue all the way up the food web or chain. Because the amounts of POPs become more and more concentrated at each trophic level, some of the ocean’s apex predators are at risk of gaining potentially fatal levels of POPs within their bodies.

One large apex predator that is heavily impacted by the bioaccumulation and biomagnification of POPs is the orca. Researchers have found extremely high levels of PCBs within the blubber of Arctic orcas, making them “the most toxic animal in the Arctic.” Additionally, scientists in Japan have found that mother orcas are passing these contaminants to their young through their milk, which has high fat content. PCBs are known to cause problems with reproduction, and studies are currently being conducted to see if and how POPs are impacting orcas in other ways.

Governments are slowly starting to realize the importance of countering the negative impacts of these pollutants. The production of DDT was banned in the United States in 1972, and more chemicals are being banned each year. In 2004, the Stockholm Convention on Persistent Organic Pollutants came into effect and internationally bans the production of PCBs and other harmful chemicals. These bans have proven to be mostly effective, and the environmental levels of many of these toxins have already started to noticeably decrease.








Plankton Tow

Plankton Tows are a great Oceanographic tool used to sample the microscopic life in the ocean. A jar is attached to the end of the net, while the two are pulled by a boat or dingy. In order to increase the amount of plankton in the jar, a longer tow is suggested. As the tow is pulled through the water excess water will exit through the mesh netting while the plankton is trapped into the jar at the end. To examine these microscopic organisms, you will need a microscope!

Depending on the size of the mesh netting you will collect different types of plankton. Large mesh netting will only collect large zooplankton (animal plankton), while smaller netting will allow you to collect not only those large zooplankton but also phytoplankton (plant-like plankton)! Here at CIMI we use the smallest mesh netting possible to allow students to see both zoo and phytoplankton. After examining you plankton sample you may be able to tell what ocean organisms are reproducing, or how the ocean’s temperature or currents are behaving.




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