Wednesday, March 14, 2018

Water on Mars and the deep ocean

By Jana M. del Favero

English edit: Katyanne M. Shoemaker

   At the end of September of 2015, NASA scientists publically confirmed the existence of liquid water on Mars, the Red Planet ( I remember when this news was released and how it caused certain uproar over the possibility of finding life there.

Landscape of the mysterious Red Planet; from the movie The Martian (

   We know that life depends on water: it is the largest constituent of every living being (e.g. the human body is composed, on average, of 60% water), it is necessary for photosynthesis, and it is indispensable for several other vital functions. However, the phrase just quoted neglects an important detail: life, AS WE KNOW IT, depends on water.

   This made me remember the following cartoon, about two giant tubeworms talking to each other:

   I had posted this cartoon on my personal Facebook page previously, but then I reflected: how many of my friends know what giant tubeworms are? Or what hydrothermal vents are?

   Tubeworms are marine invertebrates in the phylum Annelida (yes, the same as the earthworms) and the class Polychaeta (aquatic worms), but they are sessile, i.e. they live fixed on an underwater surface. Their body is rounded by a tube, which extends the length of the whole body. The one illustrated in the cartoon are of the species Riftia pachyptila, popularly known as the giant tubeworms. These worms can live several kilometers down in the ocean, and they can reach a length of 2.4 m with a diameter of 4 cm. (more information on:

   A hydrothermal vent is a fissure in a planet's surface from which geothermally heated fluid emerges. The water that penetrates the crust at deep depths reacts with the minerals present, undergoing physical and chemical changes along the way. Usually there is an “oasis” of life along the hydrothermal vents. This is due to chemosynthesis, a process in which microorganisms use chemical energy to produce organic matter from carbon dioxide.

   Prior to the discovery of hydrothermal vents in the 1970s, the scientific community assumed that all life in the ocean depended on photosynthetic production, mainly produced by phytoplankton. Since photosynthesis depends on sunlight, it was like saying that all of the life in the oceans depended solely on the sun! The hydrothermal vents and the abundance of organisms that live around them proved the opposite.

   And that's the point I wanted to get to in this post: WE KNOW AS LITTLE ABOUT THE OCEAN AS WE KNOW ABOUT SPACE!

   We have explored around 1% of the oceans, and they cover 80% of our planet.(,58d9a38790aea310VgnCLD200000bbcceb0aRCRD.html)Most of the ocean is only about 3 km deep, but Mars is about 60 million miles away from Earth! I am not saying that scientific exploration of space is not important, but I wish that the amount of money invested in space studies and the media attention space discoveries receive would also be given to the oceans. We know so little still, and yet they are so much more present in our lives.

Thursday, December 21, 2017

Two reasons to watch the documentary “Mission Blue”

Translated by Lídia Paes Leme

Edited by Katyanne M. Shoemaker

In our first post in the Women's session “Old challenges for current women” we received a suggestion by Prof. Otto Muller P. Oliveira to post about the documentary “Mission Blue.” Indeed this documentary deserves a special mention in our blog because, aside from the excellent production, its content is simply inspiring.
The documentary “Mission Blue” was released in 2014 and tells the story of the incredible biologist Sylvia Alice Earle, explorer, author, mother, grandmother (amongst a thousand other possible titles) and her campaign to create a global coalition of marine protected areas, called “Hope Spots.”

When watching the movie, it is impossible not to fall in love with and be inspired by two “characters.” The first is the organization itself, also called Mission Blue (, which was created in response to the prize Sylvia Earle earned in 2009 at “TED PRIZE WISH” (watch the talk here). In that talk, Dr. Earle encourages the use of all possible media (movies, expeditions, internet, new submarines) in a campaign to inspire public awareness and support for a worldwide network of marine protected areas. If these “Hope Spots” are wide enough, it could be possible to save and restore the planet's blue heart! Today, Mission Blue is a coalition of over 100 groups, from multinational corporations to groups of scientists, concerned with matters of ocean conservation. Mission Blue's website brings an interesting but scary statistic: only 2% of the World’s ocean is protected, hence the importance of this kind of effort.


The second reason to fall in love with this film is the main character, Sylvia Earle, a woman that turned 80 in August 2015, who actively keeps studying, exploring, diving, and defending the ocean (learn more Sylvia completed high school at the age of 16, undergrad at 19 and her masters at 20. During her Doctorate, this rhythm slowed down, due to marriage and kids, but soon Sylvia returned to her frantic pace. In 1964, when her kids where only 2 and 4 she traveled for 6 weeks on an expedition in the Indian Ocean. According to Sylvia, she didn't know she'd be the only woman on board, for she was invited as the only botanist, not only woman. A reporter approached her in Mombassa, Kenya, from where the ship would depart, and Sylvia remembered being interested in talking about her work, but the reporter only wanted to know about what being on the ocean with so many men would be like. After all, the article was called “Sylvia sails away with 70 men, but she expects no problems.”
Despite everything appearing well, Sylvia implies in some interviews that her scientific expeditions may have lead to the end of her first marriage. This is a recurring difficulty faced in the scientific world; it is common to have campaigns where the scientists are away for weeks, sometimes months, without any communication with family. In 1966 Sylvia finished her Doctorate, and in 1968 she traveled 30m deep in the waters of the Bahamas in a submersible, 4 months pregnant with her 3rd child and in her second marriage.
In 1969 she signed up to participate in the project Tektite, where scientists lived weeks in a laboratory placed under the sea, at 15m depth. Despite her 1000+ hours of diving experience and her excellent written proposal, she was not allowed to live together with men underwater in Tektike I. The following year however, she was invited to lead the Tektite II project, with a women-only team. The success of this team was an important milestone for women in research, and it set a precedent for future aquatic and space expeditions to include women in their teams.

Picture: Bates Littlehales.

After her experience as a mermaid, Sylvia became a popular face in the media and her career took off (we'd say, all other qualities aside, she also has a lovely face). In 1979 Sylvia walked on the ocean floor at depths never before touched by any other human. This was done using what is called a JIM SUIT, and was used at a depth of almost 400m. This adventure resulted in the book “Exploring the Deep Frontier.”

Image: Dr. Sylvia Earle in Deep Rover Submarine. Font:

In the 80's, together with the engineer Graham Hawkes, she started a company to create submersible vehicles, like Deep Rover. This partnership ultimately led to her third marriage, one where the offspring were the submarines created by them. One of her daughters currently works with her in her company.

When asked if she had problems reconciling family and career, Sylvia says yes, many, and that she tried to rearrange her life, having a laboratory and a library at home. For women that dream about following a scientific career, Sylvia advises “Try, you'll never know how it would be if you don't try.”


Wednesday, November 8, 2017

The extraordinary life of whale carcasses in the deep ocean

By Joan Manel Alfaro Lucas

Translated by: Lídia Paes Leme

Edited by: Katy Shoemaker

This story starts in 1987, when, during an oceanographic expedition lead by Dr. Craig Smith (University of Hawaii), the research robot Alvin found a whale carcass on the ocean floor in Santa Catalina Bay, California, 1240 meters deep (Smith et al., 1989). This discovery reinforced an idea that had been suggested before, that even though whale deaths are common in coastal zones, many die in spots far away from beaches and sink down to the depths of the ocean.
The deep ocean covers 63% of the planet's surface and is considered the biggest biome on Earth. It is unique and extreme due to its low temperatures, high pressure, and darkness (light doesn't penetrate more than 200 meters below surface, where the deep ocean starts). The absence of light makes organic matter production via photosynthesis impossible. Because of this, the deep ocean ecosystem is limited in food sources and depends almost exclusively on the sinking of organic matter produced in the surface waters. In the vast, cold, dark deserts of the deep ocean known as the abyssal plains, the few organisms that survive there filter water and sediments to take in the little organic matter that sinks down from the surface.
So now what about that Californian whale that Dr. Smith found? The carcass was completely missing meat, and other indicators suggested the whale carcass had been there for several years. However, the skeleton and the sediment around it were bursting with life! There were worms, snails, gastropods, dense mats of bacteria, and bivalves such as clams and mussels. The carcass was a real oasis of life in the deep desert of the bay. The scientists began to understand that, for an environment so poor in nutrients, the arrival of a whale carcass is an extraordinary event.
Whales are the largest animals that inhabit Earth. The blue whale can be 30 meters (~100 feet) long and weigh 120 kilotons and is the largest animal that has ever existed on our planet. To the desert depths of the ocean floor, their carcasses are the biggest source of organic matter that arrives from the surface. One carcass from a 40-kiloton whale is the equivalent of 2000 years worth of organic matter falling down at once!

Image 1 – Whale carcass on the deep ocean floor of Santa Catalina Bay, California, densely colonized by chemosynthetic bacterial mats. Photo by Craig R. Smith, University of Hawaii, USA.

Some of the organisms found for the first time on the carcass by Dr. Smith became much more interesting when identified. For example, some bivalve species found there are known to have symbiotic relationships with chemosynthetic bacteria. Those mussels feed on the matter produced by the bacteria, a process similar to what shallow water corals have with photosynthetic organisms. As it turns out, the dense bacterial mats found on the carcass were of that kind of bacteria.
Similar to vegetables in the terrestrial environment, these chemosythetic bacteria form the base of the food chain in the deep ocean. Chemosynthetic communities feed on organic compounds, some of which can be abundant on the sea floor. This is the case in hydrothermal vents, which form in parts of the floor where volcanic activity is elevated and hydrocarbons flow from underground reservoirs (post about hydrothermal vents here). The bivalve species associated with the whale carcass were discovered for the first time at cold hydrothermal vents! These similarities suggested that the whale carcass acts as a trampoline for the common habitants of different chemosynthetic communities to disperse, as they are usually separated by distances larger than can be reached by larval dispersion (Smith et al., 1989).
This discovery, other than being revolutionary for the ecology of chemosynthetic communities, led several groups of scientists to research more about these ecosystems. Rather than looking for a carcass on the vast ocean floor (a real needle in a haystack situation), scientists started to sink dead whale carcasses with weights. They were able to sink them in a determined spot where they could sample whenever needed. After these experiments, scientists began to understand that not only chemosynthetic communities developed in the carcasses, but also there were extremely diverse and abundant communities that explored the carcasses in amazing ways… for almost a century!

Image 2 – Hagfish feeding on a whale carcass during the ecological state of the mobile necrophagous organisms in Santa Catalina Bay, California, USA. Photo by Craig R Smith, University of Hawaii, USA

The whale carcasses develop mostly three ecological successive states, meaning three communities can be distinguished throughout time (Smith et al., 2015). The first stage starts with the arrival of the carcass in the bottom and includes the mobile necrophagous organisms. Hundreds of animals, like hagfish, drill the meat while sharks bite big chunks off. These communities, similar to vultures in a savanna, remove several dozen kilograms by day and can consume all the meat in up to two years, depending on the size of the carcass.

Image 3 – Crabs, snails, and anemones colonizing the skeleton during the enrichment and opportunist stage in a whale carcass in Monterey Canyon, California, USA. Photo by the Monterey Bay Aquarium Research Institute. USA.

The second stage involves the enrichment of opportunists and can also last up to two years. During this period, high densities of worms, crustaceans, and other invertebrates colonize the sediment around the skeleton that was exposed after the flesh was consumed. These invertebrates feed directly on the left over fat and meat left behind by the necrophagous organisms, as well as the bones, which are rich in protein and fat.
The last stage, the one Dr. Smith's whale was in when he found it, is the sulphophilic stage. Some microorganisms are able to penetrate the dense bone structure and access the big quantities of fat remaining in the interior of the bones. These organisms use the sulfur dissolved in water to digest the fat, creating inorganic compounds as secondary products. Similar process can also occur in the surrounding sediment, which was impacted by the organic matter of the carcass. This creates enough of a flux to develop a community based on chemosynthesis. This is the longest stage, lasting up to 80 years.
The discoveries around whale carcasses don't stop there. Since 1987, when Dr. Smith studied the first deep ocean carcass, 129 new species have been discovered, many of them only found in those communities. The most surprising one was discovered in 2002, when Osedax, a new kind of worm, was discovered in Monterey Canyon, California, at 2891 meters deep (Rousse et al., 2004). The species in this genre are sessile and don't have a mouth nor anus, nor any kind of digestive system, yet they feed on whale bones!
Osedax have a structure called a root, which helps to answer the multiple mysteries surrounding these organisms. This structure, with globular ramifications, fixes the organism to the bones and has pumps that acidify the bone matter. The “soup” produced in this process is sent up through the root into internal structures, where endosymbiotic bacteria are responsible for digestion. These worms are capable of completely decaying a whole juvenile skeleton (containing less calcified bone or fat then adults) in one decade. Impressive, no? Just wait…
All of these structures and endosymbionts only apply to female Osedax. The males are microscopic dwarves that live inside of the females, as simple sperm reservoirs. The Osedax larvae that are found on a skeleton develop as female, but if they find other females, they can get absorbed and develop as pedomorphic males, meaning they only develop sexually and not fully morphologically, retaining larval characteristics. Each female can absorb hundreds of males, which is believed to be a successful reproductive strategy.

Image 4 – Whale bone densely colonized by Osedax in Monterey Canyon, California, USA (left) and Osedax japonicus specimen with a yellow-colored root. Photos by Monterey Bay Aquarium Research Institute, USA, and Norio Miyamoto, from Japan Agency form Marine-Earth Science and Technology, respectively.

Organisms like Osedax show that whale carcasses are not only an oasis of life in the deep ocean, but also showcase uniquely evolved and specialized life forms. However, are the carcasses sustaining similar communities in all of the ocean basins? Or, like in hydrothermal vents, does each basin sustain communities with different evolutionary histories? This kind of question is still very hard to answer because practically all of the natural and placed carcasses have been studied in the Northern Pacific.
Only in 2010 was a natural carcass discovered on the seafloor near Antarctica, and, more recently in 2013, in the Southwest Atlantic off of the Brazilian coast. The latter is currently being studied by Brazilian and Japanese researchers, and is the topic of my Master's project at the University of São Paulo. This represents the first whale sink community to be studied in all of the deep Atlantic. The results of the research are beginning to emerge, reinforcing some previous hypotheses and explaining even more about the functioning of various ecological processes.
Many questions are still to be answered, and many more will be generated in the future. These extraordinary communities, not known 30 years ago, are a bottomless source of surprises!

References, links and videos:
Smith, C.R., Kukert, H., Wheatcroft, R.A, Jumars, P.A., Deming, J.W. (1989) Vent fauna on whale remais. Nature, 341. Pp 27-28.
Rouse, G.W., Goffredi, S.K., Vrijenhoek, R.C. (2004) Osedax: Bone-Eating Marine Worms with Dwarf Males. Science, 305.Pp 668-671.
Smith, C.R., Glover, A.G., Treude, T., Higgs, N.D., Amon, D.J. (2015) Whale-Fall Ecosystems: Recent Insights into Ecology, Paleoecology, and Evolution. Annual Review of Marine Science, 7. Pp 571-596.

About Joan Manel Alfaro Lucas:

A biologist from the Universitat Autonoma de Barcelona, Barcelona, I did a one year internship at the Federal University of Minas Gerais, which allowed me, among other things, to get to know Brazil and learn Portuguese. I'm passionate about the ecology of deep ocean communities, especially chemosynthetic ones. I did a Masters at the Oceanographic Institute of the University of São Paulo, where I had the opportunity to study the first whale carcass discovered in the deep Atlantic ocean. Other than that, I have experience in oceanographic cruises, sailed 2800 nautical miles across the southwest Atlantic, sampling, sorting and identifying benthic invertebrates, stable isotope analysis, and using the R language in ecological research.

Wednesday, October 11, 2017

Ugly animals need love too!

Written by: Jana M. del Favero

Illustration by: Joana Ho

   What do a dolphin, a sea turtle, and panda bear have in common? They are considered flag species, meaning they are charismatic species that can draw public attention to a conservationist cause. This concept emerged in the 1980s as a way to ensure conservation of biodiversity. Since it is not possible to finance protection projects for all species of an area, we raise the status of a charismatic species as a means of supporting its overall ecosystem. When I was an intern for the Tamar Project, I was used to receive tourists at the Ubatuba base to talk about sea turtles. While teaching them about sea turtles, I ended up also teaching them about the fish that they consumed and the damages garbage and automobile use in spawning areas caused, etc. The main message always went through several other messages. Whenever we talk about the importance of preserving the flag species, we also talk about the importance of preserving the entire ecosystem.

   Although it is an efficient concept (who does not think about the Panda Bear when thinking about WWF?), its application requires caution. By prioritizing flag species, you run the risk of not preserving those who really need to be preserved. It is important to remember that several species are threatened with extinction. Some scientists even argue that we are going through the sixth major extinction of the Earth (episodes in which large numbers of species go extinct in a short period of time).

    According to scientists all prior mass extinctions were caused by natural catastrophes, such as the fall of a meteorite. However, WE (human beings) are causing the sixth extinction! Paradoxically, although WE are causing the sixth extinction, WE are also the ones that can prevent it from being more tragic.

   So, it was in thinking about the protection of a group of endangered and "disadvantaged" animals that the biologist Simon Watt created the “Ugly Animal Preservation Society.” No, that is not a type, this idea was quite contrary to the use of traditional flag species. According to the creator, it is not fair that the panda gets all of the attention.

   The innovative idea of Simon Watt did not stop with the creation of the society. To raise funds and save aesthetically unprivileged species, he and a group of artists ventured into the United Kingdom, performing shows and stand up comedy, in which each artist featured an ugly animal. At the end of each evening, people could vote on what should be the mascot of society.

 Among some strong competition of the weirdest frogs, salamanders, snails and insects, the winning mascot was a fish, the Blobfish. Besides being ugly, this fish, scientifically called Psychrolutes marcidus, inhabits the deep waters (between 600 and 1200 meters deep) of South Australia, including Tasmania. They have no swim bladder, only the minimum number of bones needed for survival, and their body has a gelatinous consistency. But these characteristics all contribute to being able to live in their high-pressure environment, with the water around them as their main structural support.

   But I confess that I found the vote somewhat unfair. Knowing that every 10 meters that we dive to find the Blobfish, the pressure increases by 1 atm. We would meet the ugly creature in an environment with more than 60 atm of pressure pushing down on us, and our organs would crush and we would probably look like paste (actually we would have died long before!). Meanwhile the Blobfish would look like an "ordinary" fish and not the gelatinous creature we thought so ugly while we analyzed it on the Earth’s surface, at only 1 atm.

Cover of the book written by Simon Watt with an image of the mascot of the "Society of Preservation of Ugly Animals," the Blobfish.

   Another marine fish that competed as the ugliest animal was the European eel (scientific name: Anguilla anguilla). Although it is critically endangered and it looks more like a snake than a fish, I believe that this species should not even be in this competition because they are wonderful! The European eel is a euryhaline fish, which withstands great variation of salinity, and is catdromic, meaning it grows in rivers and spawns at sea. In addition, it has leptocephalus larvae, which look beautiful, last about 3 years, and reach up to 8 cm in length!

European eel: adult (left) and larva (right)

   So, have I been able to convince you that the European eel and the Blobfish are not ugly, but that they do need our attention and protection?

   In your opinion, which endangered animal is ugly and should be preserved?

About the “Ugly Animal Preservation Society” (Come in and laugh a lot watching the videos):

Thursday, September 7, 2017

Why algae are not plants

By Gabrielle Souza

   When we walk along the beach and see seaweed, we associate it with terrestrial plants. Afterall, scientific evidence strongly suggests that plants evolved from green algae in the Paleozoic Era. However, they are quite quite different in many ways. Algae, like terrestrial plants, are eukaryotic organisms (the cell has several organelles including a nucleus surrounded by a membrane) and photosynthetic autotrophs (produce their own food through photosynthesis). 

   The word algae comes from Latin and means "marine plant," but you must be aware that not all algae live in the water. Some live in terrestrial environments associated with fungi, in a mutually beneficial relationship, or symbiosis, forming so-called lichens.

   One thing is important to keep in mind: while the plants belong to a single Kingdom, the Plantae, the term "algae" encompasses many distinct taxonomic groups in the Kingdom Protista, including the Stramenopila (brown algae and diatoms), Rodophyta (red algae) and Chlorophyta (green algae) (Nybakken & Bertness, 2005). 

  Thus, due to the complexity and constant taxonomic changes of these organisms, we will not go into details of classification of this polyphyletic group (they do not share a common ancestor) called "algae," but we will focus on its general characteristics.

Lichen on a granite rock of the Serra do Mar, Joinville City, Santa Catarina State, Brazil

   Algae have several forms of stuctural organization. They can be found in unicellular forms such as diatoms and dinoflagellates, or as multicellular filamentous forms. They can form colonies that are physically united, and their organization can be defined between amorphous colonies that do not have defined numbers of cells, or those that present complex organization in number of cells and defined forms. They can also take planktonic or benthic forms (learn more about these forms here: The stalk may be divided into cells, or it may not and instead take a tubular shape (cenocytic). Among these various forms, it is common to hear the term “microalgae” when they are microscopic, and “macroalgae” when they are visible to the naked eye.

   Usually, the macroalgae are confused with plants. One of the main characteristics that differentiates macroalgae from plants is their structure. They may appear similar, but the macroalgae do not have specialized organs and tissues, and they are not vascularized. They also do not have the capacity to form a structure with flowers, leaves, roots or a stem. The multicellular algae just have a stalk to support its filaments.

Multicellular algae; B) Unicellular algae (dinoflagellate); C) Multicellular algae; D) Unicellular algae

   Now, what about underwater plants? Are all of those green things in the aquarium algae? No! An example of an aquatic plant is Elodea, a common waterweed which is widely used to decorate aquariums and artificial aquatic environments. This plant belongs to the group of Angiosperms, of the Kingdom Plantae. 

 This kingdom is comprised of vascular and avascular photosynthetic organisms, that is, with or without the presence of vessels that are responsible for the conduction of mineral salts and water. Vascularization is also responsible for the presence or absence of the reproductive parts; in the case of Angiosperms these reproductive parts generate flowers, leaves and fruit. 

   The leaves of the submerged aquatic plants are generally very thin and stubby, allowing them to support turbulence and oscillations of the water, without tearing. The leaves of the aquatic plants also have a permeable surface, which aids in internal circulation of the air.

Elodea (scientific names: Egeria densa, Egeria brasiliensis)

Related posts


NYBAKKEN, J.W. & BERTNESS, M. D. 2005. Marine Biology: an ecological approach (6º ed.)

MIGOTTO, Alvaro E.. Dinoflagelado: fitoplâncton, dic, unicelular, planctônico, cebimar-usp. Cifonauta- Banco de Imagens de Biologia Marinha. Disponível em: <>. Acesso em: 06 dez. 2016.

LAS ALGAS EUCARIOTAS. Disponível em: <>. Acesso em: 06 dez. 2016.

PATTERSON, David J.. Algae: Protists with Chloroplasts. Disponível em: <>. Acesso em: 06 dez. 2016

AGUIAR, Celio. As Algas marinhas bentônicas. Projeto Ilhas do Rio. Disponível em: <>. Acesso em: 06 dez. 2016.

SIENA, Ádamo. Elódea: Alga? Não! Planta aquática. Disponível em: <>. Acesso em: 06 dez. 2016.

AOYAMA, Elisa Mitsuko; MAZZONI-VIVEIROS, Solange Cristina. ADAPTAÇÕES ESTRUTURAIS DAS PLANTAS AO AMBIENTE. 2006. 17 f. Tese (Doutorado) - Curso de Programa de Pós Graduação em Biodiversidade Vegetal e Meio Ambiente, Instituto de BotÂnica – Ibt, São Paulo, 2006. Disponível em: <>. Acesso em: 16 dez. 2016.

Thursday, August 10, 2017

Seagrass: canaries of the sea

By Juliana Imenis, Juliana Nascimento, Larissa de Araujo, Natalia Pirani, Otto Muller and Paula Keshia

In the early 20th century, coal miners frequently carried caged canaries to work. The little birds saved many miners' lives because their sudden death or sickness indicated a possible gas leak. An alarm would sound and the mine would be evacuated.
We could say the canaries were bioindicators, or organisms that indicate a possible environmental problem through their behavior or health status. Today, we no longer have a need to sacrifice the canaries because we have electronic indicators that can tell us about possible mine disasters.

Like the canary, some organisms are extremely sensitive to pollution and habitat alterations; their populations tend to diminish or even vanish quickly after environmental modifications take place. Other organisms may be very tolerant to poor environmental conditions and can sometimes have a population boom in areas where the conditions would be inadequate to the majority of other species. One of these bioindicators is the marine phanerogam, also known as marine seagrass.

Image by Joana Ho

This particular group of plants grow on the sea floor, have elongated straight leaves, and subterraneous stalks, called rhizomes. Seagrass may live completely immersed in water, and they are found in coastal waters of nearly every continent. Despite being known as “seagrass”, this group is closer to the lily and ginger families than grass (Figure 1). They are an important part of the diet of manatees and sea turtles, and they are used as habitat by many other sea animals (Figure 2), including commercially important fish and crustaceans. Although difficult to quantify, seagrasses have a large aggregated commercial value, estimated to be up to 2 million dollars a year. They also play an important role in sequestering carbon into their biomass and sediment, thus decreasing the carbon dioxide (CO2) concentrations in the atmosphere. This helps promote nutrient recycling, coastal protection, and improve overall water quality.

Figure 1 – Morphology and occurrence in the natural environment of genera Halophila. Despite being known as “seagrass,” this group is closer to the lily and ginger families than grass. Adapted from Sarah Lardizabal schematics.

Figure 2 – Many animals visit the seagrass fields searching for food.

In Brazil, despite controversial information and the necessity of more genetic studies to differentiate the species correctly, there are so far, five known species of seagrass (Figure 3): Halodule wrightii Ascherson; Halodule emarginata Hartog; Halophila baillonii Ascherson; Halophila decipiens Ostenfeld and Rupia maritima Linnaeus. Seagrass are considered to be great environmental quality indicators, because they are very sensitive to light and nutrient availability variations.

Global climate change has many impacts on the marine environment, including the rise of global average sea surface temperatures, variations in pH (ocean acidification), and alterations of ocean currents. These are some of the rapid changes in marine environment that have been seen by researchers, and their consequences are still little known. There are many factors involved in the interactions between environmental variables and biological communities, making overall consequences hard to forecast (Figure 4).

Figura 2.jpg
Figure 3 – Identification of seagrass species can be controversial, but nowadays it is defined that there are five species along the Brazilian coast. Marques & Creed 2008.

Figure 4 – Many studies have been developed in this rich environment, but more research is needed if their importance and probable environmental changes are to be considered.

Seagrass need specific environmental conditions, like low turbidity and high incidence of light. They are suffering local reduction and in some places completely vanishing, indicating that the anthropegenic environmental changes are happening fast, not giving the organisms enough time to respond to the new conditions. The capacity of ecosystems to respond to impact and return/maintain their original conditions is called resilience.

Although the degree and type of impact on seagrass may vary with geography, some hypothesis were generated by the Benthic Habitat Monitoring Network (ReBentos) about how climate change may affect them: (1) the increased concentration of nutrients, given the increased quantity of rain, may cause changes in the community composition, favoring the occurrence of opportunistic species, which can be damaging for the local species; (2) changes in sea surface temperature can affect tropical species, favoring the extension and displacement of their occurrence limits towards higher latitudes; (3) extreme events, like floods and storms, may cause reduction or disappearance of seagrass in a quick and abrupt way; (4) the increased quantity of continental matter in estuaries may affect the abundance and composition of the communities, due to the increased turbidity and salinity changes. On the other hand, the reduction of rain and/or increased penetration of seawater into continental waters could increase or alter the estuarine seagrass' area of occupation; and finally (5) days or week-long heat waves, derived from external events, may reduce or extinguish fields in shallow areas.

As an example of evidences that support these hypothesis, we can mention a study published by the Journal of Experimental Marine Biology and Ecology by Ricardo Coutinho and Ulrich Seeliger, that, in 1984, observed that the species R. maritima, although tolerant with eutrophicated conditions, was shadowed by epiphytes and macroalgae that grew due to an excess of nutrients in the water. Those organisms tangle in this seagrass species, causing reduction on its photosynthetic rates and increasing their drag, facilitating their detachment when subjected to waves and currents. Another example is the study published in the Marine Ecology by Frederick T. Short and collaborators, that in 2006 observed the reduction of H. hrightii through the movement of sediment, caused by stronger and more frequent storms, which buried the fields of seagrass.

Therefore, as mentioned by other authors, we can consider seagrass as the canaries of the sea, important in diagnosing the environment's health in response to global climate change. Certainly, the loss of these ecosystems will bring not only economic loss, but also the loss of biodiversity, a factor that is much more valuable and difficult to measure.

To know more:

COPERTINO, M.S.; CREED, J.C.; MAGALHÃES, K.M.; BARROS, K.V.S.; LANARI, M.O.; ARÉVALO, P.R.; HORTA, P.A. (2015). Monitoramento dos fundos vegetados submersos (pradarias submersas). IN: TURRA, A.; DENADAI, M. R.. Protocolos de campo para o monitoramento de habitats bentônicos costeiros - ReBentos, cap. 2, p. 17-47. São Paulo: Instituto Oceanográfico da Universidade de São Paulo. Disponível em: <>. Acesso em: 04 nov. 2015.

MARQUES, L. V.; CREED, J. C.(2008). Biologia e ecologia das fanerógamas marinhas do Brasil. Oecologia Brasiliensis, v. 12, n. 2, p. 315 - 331.

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Juliana Imenis Barradas, CCNH-UFABC, PhD student in the postgraduate program in Evolution and Diversity, biologist, Master in Zoology (UFPB).,

Larissa de Araujo Kawabe, CCNH-UFABC, master graduate student of in the postgraduate program in Evolution and Diversity, biologist.

Juliana Nascimento Silva, CECS-UFABC, undergrad in Environmental and Urban Engineering (UFABC)

Paula Keshia Rosa Silva, CCNH-UFABC, mestranda em Evolução e Diversidade (UFABC),

Natalia Pirani Ghilardi-Lopes, CCNH-UFABC, professora adjunta, bióloga, doutora em Botânica (USP),

Otto Müller Patrão de Oliveira, CCNH-UFABC, professor adjunto, biólogo, doutor em Zoologia (USP),