Temperature, metabolic rates, and the future of your lineage

We all know that during spring, when the light and temperature start to rise, life blooms everywhere. The increase in temperature during this season activates most organisms, especially ectotherms, also known as cold-blooded animals. In these animals, the relationship between metabolism and temperature is direct, usually following an exponential function. Examples of ectotherms are fish, reptiles, insects, and, of course, zooplankton. In endotherms, such as mammals and birds, the relationship is more complex and dependent on multiple factors.

For an ectotherm, as the temperature increases, metabolic processes speed up. To quantify the effect of temperature on different metabolic rates, scientists usually use the Q10 coefficient (which has nothing to do with the coenzyme of the same name). The Q10 of a process is defined as the increase it undergoes when the temperature increases by ten degrees Celsius. Thus, a Q10 of 2 means that the speed of a metabolic process doubles when the temperature rises by 10°C. Obviously, not all rates respond equally to temperature, and sudden increases can lead to imbalances in different functions. Usually, however, if the increase is gradual and not too exaggerated, with sufficient time, the different physiological rates will balance out. This process is called thermal acclimation. When this response to temperature includes changes in the genome and is transmitted from generation to generation, we speak of thermal adaptation.

Before equilibrium is reached, however, the organism undergoes a series of uncouplings in its metabolic processes that can lead to a decrease in its survival capacity and even death. Therefore, when we talk about an organism’s resistance to temperature, we usually define its thermal window. These values ​​are defined for each species adapted to its environment. If the same species inhabits both tropical and cold zones, it is usual for the values ​​of individuals in tropical zones to be displaced to the right (toward higher values ​​at higher temperatures). Some species that have a very wide range of thermal amplitude, while others are restricted to a very narrow range of temperatures. In plankton, we have everything. Keep in mind that there is plankton in both polar and tropical regions, or hydrothermal vents. We even find plankton in tide pools that can fluctuate by tens of degrees Celsius in 24 hours. No matter how harsh the living conditions are, there will always be a species that finds its niche and survives.

Although species are usually adapted to the thermal conditions in which they live, they have some plasticity and can end up invading new habitats, and over time, colonizing and adapting completely to them. However, in nature, competition is fierce, and if the adaptive process is slow, there is always the possibility that another, already adapted, species will take its place. An example of this is the migration that many planktonic species are undergoing towards the north, to follow temperatures closer to those they were accustomed to. Thus, Calanus helgolandicus is replacing Calanus finmarchicus in the North Atlantic (which has led to a gradual collapse in cod fisheries), and Calanus hyperboreus (native to the Arctic Ocean) is increasingly found farther north. The problem is, as always, at the extremes. Species from very cold regions will inevitably disappear if the temperature continues to rise. Species from very warm climates will have to face extreme situations and, if they cannot adjust their metabolism in time, they may end up disappearing as well. One concerning issue in this regard is the heatwaves, which are becoming more and more frequent and can put many organisms in serious difficulties in just a few days.

So, what does the future hold? Concerning plankton, I am sure we will experience changes in the coming years. In fact, we are already observing some, as we mentioned earlier. Some authors point to a massive dominance of jellyfish and other gelatinous plankton in most oceans. Others predict a significant decrease in algae production, with its consequences for the entire food web. It is also important to consider that organisms from warmer climates are usually smaller than those from colder climates. This results in changes in the structure of food webs and, ultimately, the entire marine ecosystem. A few degrees of average water temperature can stop upwelling of cold nutrient-rich waters, change currents (affecting the climate of the entire planet), and cause massive migrations in marine organisms (well, those that can escape, which are not all). Practically, all scenarios point to a reduction in fish populations.

It is true, however, that if we do the work and stop CO2 emissions as much as possible, we will not see results until maybe 50 or 60 years from now. Moreover, without significant changes in our current lifestyle, it is impossible to talk about a sufficient reduction in emissions. Consequently, when results on the ecosystems begin to be seen, many species will have likely been lost along the way, and the sea we know will be quite different. Then, should we do something?


It is clear that the conservation of the ecosystem has never been a strong incentive for any government, probably because of a lack of education and awareness of the importance of nature. Nature is not just what you see in the small forests you enjoy on weekends, or the four little fishes you see on the beach. Nature is more complex than we think and is interconnected within the entire planet. If one link fails, others may collapse. Life will go on, even if the temperature rises by 10°C, but under conditions that may not be favorable for us, humans, and for many other species as important as us. We believe we are above other species because we are “smart”. Intelligence is, however, something defined and measured by human standards. Who is smarter, an architect that designs a 10-floor house or an ant that can build a huge anthill, proportionally more complex and larger than the previous house? Actually, ants have been on Earth near 100 million years, whereas we, humans, are here for only 200-300 thousand years. 

Coming back to climate change, the sad reality is that if effective action is taken in the end, it will not be to conserve nature, but because hunger, desperation, and the collapse of entire human populations will force extreme measures. Which politician will sacrifice today’s electoral votes by taking restrictive and annoying measures that may not have visible repercussions until he or she is dead? Unfortunately, very few, if any. However, it is crucial that we all understand that doing everything possible to conserve nature today is the only solution to ensure the survival of our children and grandchildren. If you don’t consider relevant taking energy-saving measures, reducing emissions, etc. for four species that you have been told may disappear, do it for your descendants. Think that they cannot do anything right now, but they will inherit our legacy. Or perhaps the best thing would be to do nothing and wait for us to be caught in a wave of mass extinction? It is up to you.

What is cooking in our Lab?

Our group, in the Department of Marine Biology and Oceanography at the Institute of Marine Sciences, CSIC, Barcelona (Spain), has been conducting research on the ecology of marine zooplankton for several decades. Over the years, we have explored diverse topics, both in the field and in the laboratory. For instance, we have characterized planktonic food web dynamics in various regions, including the North Western Mediterranean and remote areas such as the Arctic and Antarctic. In the lab, we have studied specific groups like marine cladocerans and particular species of copepods, as well as broader topics such as the impacts of diet on aging copepods, and the effects of sea turbulence, pollutants, light cycles, and other factors on zooplankton.

Recently, recognizing the crucial role of climate change on our planet, we have dedicated several research projects to studying the effects of temperature on plankton. Our approach is pioneering as we go beyond simple short-term effects of temperature, and instead, we have adapted copepod, algae, and protozoa populations to different temperatures over the years. This has required a monumental effort, especially during the COVID-19 pandemic when access to laboratories was restricted, considering that certain planktonic organisms require daily attention. Despite the challenges, we are now seeing the results of our hard work.

Our research takes a dual perspective, examining similar questions for copepods and protozoa, but with different approaches. For instance, copepods have a generation time of about a month, whereas protozoa can double in population almost every day.

In our current project, we are asking the following questions, always focusing on species that have been previously adapted to different temperatures:

  1. What effect does temperature have on the metabolic rates of marine zooplankton? This question revolves around the concept that metabolic rates speed up with temperature (measured by the Q10 coefficient). However, we have observed that copepods adapted to different temperatures in our study maintain their metabolic rates practically unchanged, regardless of warming. This finding has significant implications for predictive models of climate change, which often rely on data from organisms that have not been adapted. As for protozoa, the response is not as clear and requires further investigation. Preliminary data, however, suggests that protozoa may have a more limited ability to adapt to temperature compared to copepods.
  2. What effects does temperature have on the thermal windows of organisms and their survival ability? We have also observed, with copepods, that the range of temperatures in which organisms can survive shifts towards warmer areas of the thermal window in populations adapted to higher temperatures. Although the difference in thermal optimum or tolerance range is small, one or two degrees, it has significant implications for population dynamics under global warming scenarios.
  3. What effects does temperature have on the size of organisms? It is well known that most organisms follow Bergmann’s law, which states that larger species are found in colder climates compared to warmer ones. Plankton are no exception, and we have observed copepods, algae, and protozoa conforming to this rule. However, while our results have confirmed this trend in copepods, we have observed that factors such as nutrient availability and culture aging may have a more significant impact on the size of algae than temperature. Regarding protozoa, we have proposed a new hypothesis, as we have observed that much of the existing literature is based on experiments that may not be well-designed. Many marine protozoa, particularly those that consume algae, can ingest prey equivalent to several times their volume, and this ingestion is strongly linked to temperature. Bearing this in mind, it is surprising that most studies on the effects of temperature on the size of protozoa are done under saturating food conditions. Imagine if someone conducted a study to determine the effects of temperature on humans, but did so immediately after the individuals had just eaten an excessive amount of food, like half a cow (if that were even possible). The results of such a study would be misleading. Therefore, we are now trying to demonstrate that when protozoan size is measured accurately and after proper thermal adaptation, the effects of temperature on cell size are negligible.

Soon, we plan to investigate the synergistic effects of temperature with other global change variables, such as nutrient availability and pollutant exposure. However, to obtain conclusive results, some patience will be required as further research is underway. Whish us luck!

To learn more:

  • Albert Calbet, Enric Saiz. Thermal acclimation and adaptation in marine protozooplankton and mixoplankton (2022). Frontiers in Microbiology. 13:832810. doi.org/10.3389/fmicb.2022.832810.
  • Enric Saiz, Kaiene Griffell, Manuel Olivares, Montserrat Solé, Iason Theodorou, Albert Calbet. Reduction in thermal stress of marine copepods after physiological acclimation (2022). Journal of Plankton Research. 44(3):427-442. doi.org/10.1093/plankt/fbac017.
  • Albert Calbet, Rodrigo Andrés Martínez, Enric Saiz, Miquel Alcaraz (2022). Effects of temperature on the bioenergetics of the marine protozoans Gyrodinium dominans and Oxyrrhis marinaFrontiers in Marine Sciences. Volume 9, Article 901096. Doi: 10.3389/fmars.2022.901096.
  • Guilherme D. Ferreira, Afroditi Grigoropoulou, Enric Saiz, Albert Calbet (2022). The effect of short-term temperature exposure on vital physiological processes of mixoplankton and protozooplankton. Marine Environmental ResearchVolume 179, July 2022, 105693. DOI:10.1016/j.marenvres.2022.105693. Editor’s Choice article 2020-2022.
  • Carlos de Juan, Kaiene Griffell, Albert Calbet, Enric Saiz. (2023). Multigenerational response to warming in copepods is influenced by physiological compensation and body size reduction. Limnology and Oceanographyhttps://doi.org/10.1002/lno.12327.
  • Albert Calbet and Enric Saiz (submitted). Does the temperature-size rule apply to marine protozoans after proper acclimation? Functional Ecology.
  • Albert Calbet, Minerva García-Martínez, Claudia Traboni, Enric Saiz (submitted) The importance of the growth phase to understand the temperature-size rule in marine phytoplankton. Journal of Phycology.

Harnessing the power of plankton: a revolutionary approach to industry

As we already know, plankton make up the base of the marine food chain and have vital roles in supporting marine ecosystems. In addition to these very important roles, recent scientific discoveries have revealed that plankton can also be of use for industrial applications, revolutionizing various industries and opening up new possibilities for sustainable and eco-friendly solutions. Here, I walk you through some of these uses and I will try to expose their pros and cons. 

The use of plankton in biotechnology and other biology-related industries 

One of the most promising areas where plankton are being utilized is in the field of biotechnology. Plankton are rich sources of unique and diverse bioactive compounds, including enzymes, lipids, and secondary metabolites, that have immense potential. For example, enzymes derived from plankton can be used in pharmaceutical products and food additives. Lipids extracted from plankton can be used in cosmetics, nutritional supplements (e.g., omega-3 fatty acids), and aquaculture feed. Plankton-derived secondary metabolites, such as many toxins, have shown to be promising treatments for Alzheimer’s disease, cancer, diabetes, AIDS, schizophrenia, inflammation, allergy, osteoporosis, asthma, pain, etc. 

Furthermore, plankton have shown great potential in sustainable aquaculture practices, as natural and nutritious food source for fish larvae and shrimp, reducing the dependence on wild-caught fish for fishmeal and minimizing the environmental impact of aquaculture. 

Plankton are also used in the production of biofertilizers, which can enhance crop growth and productivity without the need for synthetic chemicals, and in wastewater treatment, as they have the ability to remove pollutants and excess of nutrients from water bodies, helping to mitigate water pollution and eutrophication.

The power of plankton as biofuel

Biofuels, renewable energy sources derived from biological materials, have emerged as a promising solution to reduce reliance on fossil fuels and mitigate climate change. While traditional biofuels are typically derived from crops such as corn and sugarcane, recent advancements have highlighted the potential of plankton as a sustainable and efficient source of biofuel. Phytoplankton offer unique advantages as a biofuel source, with their rapid growth, high lipid content, and potential for sustainable cultivation. Lipids extracted from plankton can be processed to produce biodiesel, a renewable and environmentally-friendly alternative to traditional fossil fuels. Plankton can be grown in controlled environments, such as bioreactors or open ponds, using sunlight, carbon dioxide, and nutrients. Plankton can be cultivated using seawater, reducing the competition for freshwater resources, which is a major concern in traditional biofuel crop cultivation. Furthermore, plankton can be grown using non-arable land, making it a viable option for biofuel production without competing with food crops.

The use of plankton as biofuel offers several additional benefits. First and foremost, plankton biofuel is a renewable energy source that can reduce dependence on fossil fuels, which are finite and contribute to climate change. Plankton biofuel has the potential to significantly reduce greenhouse gas emissions, as the production and combustion of biofuels generally release less carbon dioxide compared to fossil fuels. Since plankton can be cultivated in local waters, plankton biofuel production can be decentralized, reducing the need for long-distance transportation of fuel and associated environmental impacts.

The potential of diatoms in construction

Diatoms, microscopic single-celled algae, are not only important contributors to marine ecosystems, but they also offer unique properties that make them a promising material for construction. Diatoms possess intricate silica cell walls, called frustules, with diverse shapes and patterns, which can be harvested and utilized for various applications in the construction industry. These frustules have high strength, durability, and thermal stability, making them ideal for various construction applications. Diatom frustules can be harvested from diatomaceous earth, a naturally occurring sedimentary rock composed of fossilized diatoms, or can be cultivated in controlled environments.

One of the main uses of diatoms in construction is as a sustainable and eco-friendly alternative to conventional construction materials. Diatom frustules can be processed into diatomite, a lightweight and porous material that can be used in the production of cement, concrete, and insulation materials. Diatomite-based construction materials offer several benefits, including improved insulation, reduced weight, and increased durability, compared to traditional materials. Furthermore, diatoms have the potential to improve indoor air quality in buildings. Diatomite-based materials have high porosity, which allows for increased air circulation and can help regulate humidity and absorb indoor air pollutants, contributing to a healthier indoor environment. However, I am not sure whether with the air they let the heat (or cold) escape from the buildings. The use of diatoms in construction also has the potential to reduce the environmental footprint of buildings. Diatom-based materials have a lower carbon footprint compared to traditional construction materials, as diatoms sequester carbon dioxide during their growth process. 

A tiny solution for feeding our growing population

I did not want to end this post without exploring the use of plankton in palliating one of the major problems human populations are facing, famine. As the global population continues to soar, with estimates reaching 9.7 billion by 2050, finding sustainable and scalable solutions to feed our communities becomes increasingly critical. While traditional agriculture, livestock and aquaculture have been the backbone of our food systems, plankton, is a tiny yet mighty solution that holds great promise. 

One of the main advantages of using plankton as a food source is its remarkable ability to reproduce rapidly. Additionally, autotrophic plankton requires minimal resources for growth, primarily sunlight and nutrients, making them an efficient and environmentally friendly option for food production. Plankton also pack a nutritional punch. They are rich in essential fatty acids, proteins, vitamins, and minerals, making them a nutrient-dense food source. 

Furthermore, plankton can be sustainably harvested using innovative techniques such as vertical farming, where plankton are grown in stacked trays in controlled environments. This allows for year-round production, irrespective of weather conditions, and minimizes the risk of overfishing or depleting natural plankton populations.

The potential of plankton as a food source is not limited to the present, but also offers promise for the future. As climate change continues to disrupt traditional agriculture and fisheries, plankton farming can serve as a resilient alternative. Additionally, with its high growth rate and nutrient density, plankton has the potential to address malnutrition and food insecurity, especially in vulnerable populations.

Caveats and challenges associated to the use of plankton in industry

Despite the potential benefits, there are challenges and considerations associated with the use of plankton in industry. One of the main challenges is the scalability of their cultivation. While plankton can grow rapidly, achieving large-scale cultivation and production of these organisms is still a technological and logistical challenge that requires further research and development. Another difficulty is the potential environmental impacts of plankton cultivation, such as nutrient pollution, genetic modification, and impacts on marine ecosystems. Careful management, legislation, and monitoring of plankton cultivation practices are necessary to ensure environmental sustainability and minimize potential negative impacts. Additionally, and perhaps most important, the economic viability and cost competitiveness of plankton production compared to traditional alternatives are still being evaluated. Further research, technological advancements, and supportive policies are needed to make plankton economically viable and commercially scalable for their many uses.

The adventures of Fred the copepod

During the next days I will be posting something very different, a child’s story. The project intents to reach the youngest audience with a story about a copepod named Fred that explains, in an educational and entertaining way, what copepods are, what they do in the sea, and the problems he experiences during his life. He introduces concepts such as predation, reproduction, vertical migration, and pollution and presents other components of plankton, such as microplankton andmeroplankton. The ultimate goal is to make children and adults aware of the fragility and importance of plankton and the need to take care of the sea. The original book has two levels of reading: one designed for children from 6 years old and another for adults who want to know more about marine plankton. This dual way of providing information will reach a much larger audience. Here you have the first pages. Next pages, soon! Enjoy.

This was the last entry of my kid’s story. I hope you enjoyed it and read it to your kids to raise awareness about the fragility of the ocean and the need to take good care of it. And, if you know someone that wants to publish it (either in English, Spanish, or Catalan), let me know 😉

Microplankton and Metazooplankton from the Catalan Coast, December 15th, 2022

In these 3 videos you will find a summary of the most relevant findings from PUDEM sampling in front Barcelona. The community was rather surprising, because it seemed an end of summer one, with cladocera (Penilia avirostris and Evadne spp.) and Oithona spp. combined with a diatom bloom of very large and diverse species. I guess this community reflects the unusually warm temperatures we had this year.

I highlight the presence of the pennate diatom Bacillaria paxillifer that forms colonies in which adjacent cells glide using filamentous structures. 

The fragility of plankton

When there is a natural disaster at sea, such as the Exxon Valdez in Alaska (1989) or the Prestige in the NW Spanish coast (2002), we all immediately worry about seabirds, turtles, and dolphins and how the disaster will affect fisheries. On television, we are flooded with images of black birds, covered in oil, and dead fish on beaches. All of this is relevant and important, of course. However, no one (apart from three or four specialist scientists in the field) stops thinking about what effect it can have on the base of the food web, the plankton. We are not aware of the fact that if the plankton fails, the house of cards collapses, and we can forget about the birds, turtles, dolphins, and fish because nothing will reach them to eat and they will die irretrievably. Fortunately, although certain groups of plankton are very sensitive to hydrocarbon pollutants, the dilution effect of seawater and the mostly superficial zoning of the crude play in their favor.

It does not take a natural catastrophe to harm plankton. Fully accepted anthropogenic activities also have an effect. For example, if someone proposed cutting down an oak forest to plant exotic fruits, such as passion fruit, papaya or others, we would react by calling it an ecological monstrosity. Yet, if the case was a foreign species of oyster (like those that populate aquaculture facilities, mostly originated in the Pacific), in a bay where we do not swim, it probably would alarm no one. However, these crops destroy planktonic diversity and damage the entire marine ecosystem around them. Besides filtering a good part of the plankton present, they pollute the water and the sediments to the point of producing anoxia. If that was not enough, they are also hotspots for jellyfish and harmful algal bloom proliferations. All in all, a real ecological disaster that we completely ignore.

Mediterranean plankton

Plankton are very sensitive to pollutants, and many studies support this. I do not want to get into technicalities and flood you with data on the effect of mercury, cadmium, chromium, etc., or what are the consequences of sunblock creams or medicines that end up in the sea. What I will tell you are two anecdotic examples that I have witnessed and which were not part of any specific study, but which undoubtedly reflect the fragility of plankton.

The first example dates back to my time as a Ph.D. student, when I started growing copepods in the laboratory. To keep these small crustaceans, we used seawater filtered through cartridges with different filters. I remember once the plastic connecting screw between two cartridge holders was damaged, and we replaced it with a copper/bronze one. Almost immediately, the copepods, despite presenting a healthy appearance, stopped laying eggs. We checked the food, temperature, salinity, etc. However, we did not find any problem. Finally, one day, after turning it over a thousand times, it occurred to us that the only different thing was that screw. We installed a plastic one, and the copepods returned to lay eggs as usual. Consider that the water was only in contact with this piece for a few seconds, but it still affected them sublethally. Today, we know that copper inhibits vitellogenesis (egg yolk formation) in copepods and therefore negatively affects egg production.

Copèpod Paracartia grani from the permanent culture at the Institute of Marine Sciences, CSIC.

I witnessed another curious example during my postdoc at the University of Hawaii (USA). At that time, we carried out monthly oceanographic campaigns in Pacific waters, in which I had the privilege of participating. On those scientific cruises, we took seawater with Niskin bottles (plastic cylinders with caps at both ends) mounted in a rosette around a CTD (a device that measures conductivity, temperature, and depth). In two of those Niskin bottles, the O-ring, which ensures they close properly, and no water is lost, broke. As there were no more O-rings of the same high quality (they were free of trace metals), the technician in question replaced them with standard ones made of black rubber, which are common in plumbing. During the following cruises, in those two bottles, there was always a drop in primary production (algae production) measurements of approximately 20-30%. New, better-quality O-rings arrived, and the problem went away. Such an insignificant detail, because the rings are almost not in contact with the water, affected the algae negatively and forced us to throw away all the data corresponding to those samplings. Let me add that most Niskin bottles in use today still have the typical black plumbing O-rings. Because this was never published, it has not reached the scientific community. To publish it, it would be necessary to do more tests with different communities and more replicates. However, in the end, the problem is there.

Rosette of Niskin bottles mounted around a CTD

Many pollutants can affect plankton, some of them classic and well-known, such as hydrocarbons or heavy metals, and others emerging, which have seldom been taken into consideration, such as nanoparticles, hormones, medicines, plasticizers, etc. We know little about what effect they will have on plankton. Nor do we know if the increase in temperature will act synergistically with them to the detriment of plankton. We still have a lot to learn, but, in the meantime, I would ask you to take care of our precious and delicate sea and the creatures that live in it, including the plankton. I would also ask you to think that, although invisible, the planktonic food web makes up an ecosystem as complex and precious as an oak grove or a pine forest.

Our copepod cultures

Today I will present you our copepod cultures. Some of them have been decades with us.

Oithona davisae 10x objective
Paracartia grani 5x objective
Centropages typicus 10x objective

The nauplii of the three species are also different:

These are a nauplii of Oithona davisae. They are usually pointy towards the end and have two spines in the posterior part that are almost touching by the end.

Paracartia grani nauplii are more “rectangular-looking” and the spines are open towards the sides, never touching by the end.

In the case of Centropages typicus there are a long and a short two parallel spines in the posterior part.

Plankton and art

Those who have seen a plankton sample cannot deny its inherent beauty. From the perfect symmetry of diatoms to the complexity of some radiolarians, we can find an infinite range of shapes and colors that have been a source of inspiration for many artists, ancient and modern. Perhaps we find the maximum expression of the representation of plankton in painting. Particularly, toward the end of the 19th century and the beginning of the 20th, a series of artists exceptionally illustrated the plankton. Among these, I would undoubtedly highlight Erns Haeckel (1834-1919), who drew marine creatures, and in particular plankton, with a detail and beauty that had never seen before (Figure 1).

Figure 1. Drawing of Radiolaria by Erns Haeckel

If we talk about artists and plankton, I cannot fail to mention Miquel Alcaraz, my former advisor and friend, who recently disappeared, leaving us without a great scientist and painter of plankton (Figure 2).

Figure 2. Centropages typicus developmental stages painted by Miquel Alcaraz

Plankton have also inspired artistic creations, which are not purely descriptive. There is a long tradition of naturalists and researchers who devoted their time, around the 19th century, to create true masterpieces of art and monuments to patience, slowly placing under the microscope different species of diatoms in the correct position to create compositions that, often, remind church rose windows (Figure 3).

Figure 3. Compositions with diatoms. Left J.D. Möller, right Eduard Thum

Many sculptors also find an endless source of inspiration in planktonic creatures. For example, Mara Haseltine’s glass figures represent tintinnids, radiolarians, and other plankton organisms in a very creative way. Louise Hibbert also represents plankton, among other creatures, in her sculptures. If we move from art to artistic merchandizing, it is not difficult to find pendants inspired in plankton, usually made with 3D printing and coated with more or less precious metals. I leave you in Figure 4 a collection of all these creations (without putting commercial names or sales websites, which would not be appropriate).

Figure 4. Different sculptures and works of art inspired by plankton. Above, glass works by Mara Haseltine; middle, sculptures by Louise Hibbert; below, commercial pendants.

Cinema is closely related to painting and sculpture and is another of the world-renowned arts. We already met the Phronima in a previous post (https://wordpress.com/view/planktonocean.wordpress.com), which surely inspired the creature in the movie Alien, by Ridley Scott. However, it does not end there, from the misnamed character Plankton (it is actually a copepod) of SpongeBob animation to the short cartoon series Plankton Invasion, or the Golisopod from Pokemon (inspired by an isopod) we have representatives of plankton everywhere (Figure 5). Returning to the descriptive art, within the audiovisual medium, I would highlight the videos of Plankton Chronicles (www.planktonchronicles.org) or those of the YouTube channel from our research group (www.youtube.com/c/ZooplanktonEcologyGroupICM).

Figure 5. Plankton in cartoons.

The literary works on plankton are also extensive, and there is something to suit all tastes, more or less scientific. However, if we are talking purely about fictional literature, we should not be surprised that plankton has also inspired some other books. As an example, we could cite the book Medusa by Sergio Rossi, where some marine biologists want to prevent a voracious species of jellyfish from ending the world’s fisheries, or the Fifth day by Frank Schatzing, where lobsters full of toxic dinoflagellates explode in the faces of humans who wanted to eat them. Maybe a little far-fetched, don’t you think?

Although it sounds unbelievable, there are also architectural structures based on plankton. The diatom-house designed in Germany is an example. The Korean building that simulate the cycle of elements in the planktonic food web is another (Figure 6). There is also a team of architects called the Plankton Group; however, I do notsee much of a connection between this latter building and these creatures.

Figure 6. Left diatom house. Right building inspired by the cycle of the elements

I do not know much about the relationship between plankton and music or dance. Even so, there is a music group called Insect surfers, which released the song Plankton Dance in 2014. However, the truth is that it becomes difficult to find a relationship between that song and plankton.

Finally, even though it is not one of the seven arts yet, we cannot deny that knowing how to cook is quite an art. Well, there are a few dishes with plankton, and they are becoming fashionable as an haute cuisine ingredient. From the traditional Chinese marinated jellyfish to the sophistication of dishes with marine phytoplankton (freeze-dried algae cultures sold at exorbitant prices) promoted by the Spanish chef Angel León, we have a variety of dishes using plankton as ingredients that we can enjoy. I had myself a Calanussoup at a meeting in Germany. I admit, however, it was rather tasteless. 

Plankton are also being used in the supplements, such as Omega 3, Spirulina, etc. 

In summary, either because we enjoy art, movies, or simply cooking with plankton, it is undeniable these creatures have entered into our lives.

Microplankton sample, 11/20/2022

I leave you with a selection of pictures from the last plankton sample (2 Km offshore Barcelona, 5 meters depth, November 20, 2022). You can find the movies here:

https://www.youtube.com/watch?v=P0KFxcoq_9A for a summary of the relevant species

https://www.youtube.com/watch?v=eYfxSVCLrC4 for Acantharia

https://www.youtube.com/watch?v=6dNyRKlIk4g for a beautiful Amoeba

https://www.youtube.com/watch?v=hRdBe37iO50 for Ceratium spp.

A brief history of plankton discovery

In this post, I will give you a few glimpses of how were the early plankton-human interactions and how we managed to study these creatures. As you will see, there was already evidence from ancient Greece that there were strange beings, including plankton organisms, that did not fit into any known classification. However,perhaps the greatest work was done by a series of amateur and professional naturalists from the 16th to the 19th centuries. Their discoveries were not always published as books but were often contained in correspondence they maintained with recognized institutions, such as the Royal Society of London. Even though many valuable records are certainly lost, a good part of this correspondence is still available, and we have evidence of the exciting progress of those people who had a whole new world to discover. You will see that I give special emphasis to the first illustrations of plankton because, as the popular saying dictates, many times a picture is worth a thousand words.

Multicellular plankton

Logically, the first recorded members of plankton were possibly jellyfish and other larger organisms, particularly those that lived attached to other animals for daily consumption, such as fish. Already in the 4th century BC, the great philosopher and naturalist Aristotle first identified a parasitic copepod. He classified it, like jellyfish and other soft-bodied organisms, such as sponges and ascidians, under the name Zoophyta, something between animals and plants, and that classification lasted for hundreds of years. However, we owe the first image of a parasitic copepod (Figure 1) to Gillaume Rondelet, a French zoologist born in 1507.

Figure 1. Below, on the right and above the tuna’s gills, you can see what could be a parasitic copepod. Illustration by Rondelet (1554).

The free-living copepods had to wait slightly longer to be discovered; in 1688, Stephan Blankaart drew the first recorded free-living (freshwater) copepod (Figure 2). Carl Linnaeus (father of modern taxonomy, 1707-1778) named them Monoculus and classified them as insects. As insects, they remained for many years until the beginning of the 19th century, when Jean-Baptiste Lamarck classified them as crustaceans, along with water fleas, amphipods and isopods.

Figure 2. The first illustration of a free-living copepod, left. Possibly of the genus Cyclops from a sample of freshwater. Stephan Blankaart (1688).

Out of curiosity, the first illustration of a free-living marine copepod corresponds to Gunnerus (1770), a Norwegian zoologist who identified Calanus finmarchicus (rather numerous and important species on the Norwegian coast), although he called it Monoculus finmarchicus (Figure 3).

Figure 3. The first illustration of a free-living marine copepod. Ernst Gunnerus (1770).

Unicellular plankton

We owe the discovery of protists to Antonie van Leeuwenhoek, who with his rudimentary microscope first saw infusoria and other planktonic organisms. Between 1674 and 1716, this Dutchman, recognized as the father of microbiology, described several species of protozoa, mostly ciliates (infusoria, Figure 4), among other planktonic creatures.

Figure 4. Drawings of different infusoria and other organisms made by Antonie van Leeuwenhoek 1702.

He did not pay much attention to planktonic algae, and although he surely saw them, the first diatom (not quite planktonic) was described by an English gentleman, probably Charles King, in 1703 in a note sent to the Royal Society of London. From here, many naturalists devoted themselves to classifying, observing, and drawing protozoa (for example O.F. Müller has a detailed description with drawings of the behavior of tintinnids dating from 1779. Of course, the maximum expression of art depicting these beautiful creatures can be found in the drawings of the German Ernst Haeckel (Figure 5). This artist and scientist suggested in 1866 that all those animals (including bacteria) that he saw under the microscope should constitute by themselves a third independent animal kingdom called Protista (the first or primordial).

Figure 5. Illustrations of different protozoa by Ernst Haeckel.

Plankton research

Many years passed from the discovery and classification of planktonic organisms to the beginning of research into their role in the oceans. The first studies, purely descriptive of the diversity of life forms, were linked to large expeditions, such as those of Captain James C. Cook between 1768 and 1780 in the Pacific Ocean. In those expeditions, there is evidence, for example, of spots of the cyanobacterium Trychodesmium on the surface of the ocean. However, the first nets specifically designed to collect plankton were probably used by the French naturalists Francois Péron and Charles-Alexandre Lesueur during an expedition to Australia from 1801 to 1804. Additionally, during the long voyage of the HMS Beagle (1831- 1836), Charles Darwin used nets to collect samples of plankton. However, we own the creation of modern oceanography to the Challenger expedition (1872 to 1876), as it was the first organized specifically to collect data from the marine environment, including temperature, water chemistry, bottom geology, currents, and marine life. The HMS Challenger was equipped with laboratories and microscopes, as well as a team of six scientists.

In 1887, the physiologist Victor Hensen introduced the term plankton to describe all those animals that drifted in water currents. He was also the first to propose that perhaps marine life was not nourished by what flowed into rivers but by microscopic primary producers. Through his studies, he perfected existing plankton net designs and created one that was truly quantitative and is still used today (the Hensen net). From the analysis of his samples, he came to the erroneous conclusion that plankton are homogeneously distributed in the ocean and that there are too few of them to sustain fisheries. Facts that were refuted immediately afterward. The study of the distribution and abundance of the different plankton groups continued during the late 19th and early 20th centuries with names such as Marie Lebour (specialist in diatoms and dinoflagellates, 1876-1971), Alister Hardy (creator of the continuous plankton capture system, CPR, 1896-1985), Sheina Marshall (a pioneer in the study of copepod feeding, particularly Calanus sp. (Figure 6), 1896-1977), Hans Utermöhl (inventor of the sedimentation chambers named after him, 1896-1984), to name a few of them. The result of those studies is the discovery of daily patterns of vertical migration, for example. In 1817, the French naturalist George Cuvier made observations of the vertical migration of zooplankton, although he did so in a lake, and his study lasted only one day. More complete, marine and long-lasting were the investigations of the German Carl Chun, in 1888, on vertical migration.

Figure 6. The marine copepod Calanus hyperboreus.

Although there were hints of their behavior, what those microscopic beasts actually did in the sea was still mostly a mystery, and we had to wait until the 20th century for estimates of, for example, primary production, first with variations in oxygen measurements under light and dark conditions, and afterward using radioactive carbon. Similarly, the estimation of zooplankton production was established as a technique well into the 20th century. In 1963, Ramon Margalef established the basis for understanding the structure of the ecosystem and the relevance of ecosystem maturity in species succession. By the end of the 20th century, MR Landry and RP Hassett devised a method to estimate the impact of microzooplankton feeding on phytoplankton in seas and oceans. At approximately the same time, F Azam, T Fenchel and other collaborators conceptualized the operation of the microbial network and introduced the term microbial loop, which takes into account the tremendous importance of dissolved organic compounds and the key role of bacteria in the marine food web. All these milestones have been decisive in positioning us into current knowledge. However, although we have come a long way and have modern techniques and disciplines at our fingertips, such as satellite imaging, sequencing, genomics, and gene expression, we are still in the infancy of fully understanding (and predicting) the function of the different plankton groups in the marine food web.