Underwater: A Journey into the Unknown World of Small-sized Neotropical Fishes

Latest update August 31, 2019 Started on January 1, 2012

Check out an ichthyology team's effort on understanding the evolution of neotropical small-sized fishes and their distribution through geological time. Instagram: @underwater.blog

January 1, 2012
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In The Field

Today is our third day of fieldwork in the Amazon. During this period, I, Filipe and Pedro explored some specific habitats, such as litter leaf, sandbanks, and roots of aquatic plants. Among the stunning diversity of fishes collected in only 72 hours of expedition, the catfish species Helogenes marmoratus deserves some attention.
Fishes of the genus Helogenes were previously allocated in their own family, Helogenidae. From de Pinna & Vari’s (1995) paper on, these catfishes are considered a distinct lineage (subfamily Helogeninae) of the family Cetopsidae (commonly known as “candiru-açu” or “whale candiru/candiru baleia”). Helogenes currently comprises four species distributed throughout the Amazon, Orinoco and Tocantins River basin and in coastal rivers of the Guianas. Species of Helogenes are easily recognized by a very long anal fin, the lack of spines in both dorsal and pectoral fins, the ventral lobe of the caudal fin wider than the dorsal lobe and an adipose fin minute or absent. Individuals of H. marmoratus are found in clear or black waters in Brazil, Peru, Ecuador, Venezuela, Suriname, Guiana and French Guiana. They are brownish/reddish resembling dead leaves and inhabit litter, plant debris and roots of aquatic plants. The coloration pattern usually acts as a camouflage: these catfishes can be mistaken as a piece of wood when laying on their side to rest. Helogenes marmoratus is also known for jumping outside the water during rotenone fishing by Tukano and Tukuya indigenous people and then jumping back on the water after the water is clear. This species distinguishes from the other species of the genus by differences in fin rays counts.

References: de Pinna, M.C.C. & Vari, R.P. (1995). Monophyly and Phylogenetic Diagnosis of the Family Cetopsidae, with Synonymization of the Helogenidae (Teleostei: Siluriformes) Sazima, I., Carvalho, L. N., Mendonça, F. P., & Zuanon, J. (2006). Fallen leaves on the water-bed: diurnal camouflage of three night active fish species in an Amazonian streamlet. Neotropical Ichthyology, 4(1), 119–122.

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After a 4-month hiatus, here we go again! From August 27th to September 20th I’ll be leading this team of amazing guys through a lifetime experience in the Amazon, in my National Geographic funded expedition.

Around November 2017, just after joining the Genetics Graduation Program of the Federal University of Rio de Janeiro (UFRJ, Brazil), I applied for an Early Career Grant from National Geographic Society. A few months later, I received the most important news of my life: I got the grant! Since then, several doors opened for me and I had lots of huge opportunities, such as participating in the National Geographic Sciencetelling Bootcamp in Mexico City last March (see last post).

I am currently working on my PhD research in Genetics at the Laboratory of Systematics and Evolution of Teleost Fishes. My project aims to understand how morphological and ecological characters of the candirus evolved under a molecular framework. The candirus are a group of freshwater catfishes allocated in the family Trichomycteridae that feed on blood, mucus, scales and skin of larger fishes – some of them are known for entering the human urethra and others can even be scavengers! Their largest biodiversity is concentrated along the Amazon River basin, the main reason why I choose this place to explore. Also, the Amazon has been facing one of its most devastating moments, what emphasizes the need of making local knowledge on fauna and flora available to scientists and the general public (I’ll approach this in another post).

These photos represent some of the most important steps before going to the field: carefully selecting potential collecting points (usually via satellite images), deeply researching the available knowledge of Amazonian fishes (through papers and books) and hypothesising what can be new to science and analysing specimens from scientific collections.

My team is composed by me (Elisabeth - see background) and Drs Pedro Bragança (from The South African Institute for Aquatic Biodiversity), Axel Katz and Filipe Rangel-Pereira (both also from UFRJ). I am very proud and excited to be with these incredible scientists and friends for the next three weeks of intensive fieldwork. We’ll be sharing photos and videos over the next days and they will act as my collaborators in this blog.

Don’t forget to follow us on Instagram (@underwater.blog). We’ll be posting stories and pictures so you can feel in the field with us. I can’t wait to share this journey with you, and I hope you wish us good luck!

See you, Elisabeth

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From this year’s March 15th to 20th, I had the amazing opportunity of joining the second National Geographic Explorers Festival in Mexico City, Mexico. I and other 26 explorers that act in different areas from Latin America were invited to this unforgettable event promoted by the National Geographic Society. We were researchers, photographers, teachers, communicators, filmmakers and storytellers from several age groups that live different moments in our careers and study animals, plants, people and even minerals. We all lead super interesting projects with potential to make a difference towards a planet in balance. :)

The event was divided into two parts. The first one, the Sciencetelling Bootcamp, occurred from March 15th to 18th. This package consisted of an intense training of our abilities and potentialities as explorers. In the first two days (March 15th and 16th), the amazing Lisa Witter inspired us with her Leadership and Public Speaking workshops. We were honoured to be guided by the co-founder of Apolitical and Young Global Leader (2010) to rethink our roles as leaders and potential influencers of a community. She pushed our thinking ability to the limit, and, at least for me, many questions have arisen and a paradigm shift was achieved. The Public Speaking workshop was a training to our public presentations – a big challenge to everyone, because we had to rethink our speeches considering the impact we wanted to provoke in the audience (in only three minutes!). On March 17th, we had a photography training with the awarded photographer Jaime Rojo, whom shared with us his professional experience and some photo tips. In the next day, Jorge Alvarenga, responsible for the Impact Media, told us his history and spoke about video production. Both Rojo and Alvarenga taught us how to tell stories through images: what do we wanna say and share? How do we want people to feel? What is the story behind a photo or a video? That knowledge is crucial for an explorer. In the last day of the Bootcamp, Kara Solarz, responsible for NGS’ social media, guided us through the digital world, teaching how to promote our work to the public.

The second part of the event, from March 19th to 20th, took place in the Museo Interactivo de Economia and focused on the explorers’ works. In the Explorer Spotlight (on March 19th) all we 26 explorers had the opportunity to do a 3-minute speech about our National Geographic related works to students, invited people and NGS and NGP’s members and staff. Was beautiful to see how my explorer friends evolved in their speeches and stage presence. I am so proud of all of you! In the next day, there was the Explorer Symposium, where recognized and well stablished explorers presented their works and how they make difference in their communities.

I would like to highlight the concern of Lisa Witter and the NGS staff, especially of the beloved Gael Almeida, Jen Shook, Elisa Hickey and Cheryl Zook about the role of woman in society. All the woman in the meeting could sit together to discuss the particularities of being a woman in the work environment and personal life. We also celebrated our strength, of course. Every woman present at this meeting inspired and touched me in a different way and I can say that we have created deep connections. To all of you, I am especially grateful.

Thanks to NGS for this unique opportunity of presenting my work and meet amazing people. This was undoubtedly one of the best moments of my career. I feel proud of my progress and especially of all my explorer friends: you make THE difference!

Photos Credit: P:M Creative Lab Natgeo’s gifts photo: Lia Kajiki

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In The Field

First of all: now you can follow us also on Instagram! Just seach for @underwater.blog :)

This post is a little beyond the scope of this blog – despite it, somehow, still concerns freshwater fishes.

Different species of freshwater fishes compose several famous dishes such as pirarucu with shrimp sauce, moquecas, roasted tilapia etc. In this post, which was originally published in my personal Facebook account (and was a strong success!), I will present you an easy recipe of tucunaré or piranha sashimi. It is fun to do this kind of cooking while in the field – you can fill your stomach while relaxing with your co-workers. I learned this recipe with a very friendly and kind fisherman (Roberto) that I met during an expedition to the Serra do Amolar region, in the Pantanal of Corumbá, State of Mato Grosso, Brazil. First, I will explain a little about these fishes’ biology and then about the recipe itself. Several friends asked me to share this culinary secret in the blog and I hope you like – and try it!

“Tucunaré” is the popular name of cichlid fishes allocated in the genus Cichla. These species are important fisheries and aquaculture products that can measure up to 1m and weigh 10kg. They have a strong territorial component and compose couples during the mating season. When the couple’s eggs hatch, the adults build and protects a nest made of stones. These fishes are active hunters that feed on other species of fish, shrimps and other invertebrates. Native from the Amazon river basin, the tucunarés were artificially introduced in other areas, such as dams in the southeastern Brazil, in the São Francisco river basin and in the Pantanal. In this way, using tucunarés in this recipe is not so bad: they are exotic species in the Pantanal that compete with the native ones for natural resources.

“Piranha” is how people refer to some species of the family Serrasalmidae, which comprises 97 species allocated in 16 genera (according to Fishbase.org and Eschmeyer’s Catalog of Fishes). As reported by SpeciesLink database, seven different genera of piranhas are found in the Pantanal. Despite their reputation of being avid flesh-eating organisms (feeding on vertebrates and invertebrates), their diet also consist in some plant material, which led ichthyologists to consider them as omnivorous. The piranhas are also known for attacking humans, but there is no big reasons to worry: these incidents happen most when these fishes are under extreme stress and the injuries usually are not serious. The piranhas are native from the Amazon, Paraná-Paraguai and São Francisco rivers basins.

Taxonomic accounts: Tucunaré: Order Cichliformes > Family Cichlidae > Genus Cichla

Piranha: Order Characiformes > Family Serrasalmidae

Let’s go to the recipe!

Necessary items: a plastic pot, a knife, lemons and ginger. 1- Cut the fishes into filets and discard the rest. Wash the filets (no problems if you have to wash them in the river) 2- Cut the filets into strips 3- Put the strips in the plastic pot, squeeze the lemons over them and let it there for around 5 minutes 4- Throw away the lemon juice that will be in the pot 5- Cover the fish strips with shoyu sauce 6- Scrap a little bit of ginger over the fish 7- Mix the fish, the shoyu sauce and the ginger 8- Eat and enjoy!

Figure 1. Me, while holding a tucunaré! Figure 2. A piranha. Figure 3. Serra do Amolar location where the fieldwork was done Figure 4. Roberto, the fisherman.

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Serra do Mar is a mountain ridge that runs parallel to the Atlantic Ocean and extends for about 1,500km along the south/southeastern Brazilian coast, from Rio de Janeiro to Santa Catarina States. It is located in the Atlantic Forest, a highly endangered tropical forest that only relies on less than 20% of its original cover and exhibits high levels of plant and animal endemism¹. Its slopes range between 800-100m and comprises many small isolated watersheds that, as many of the coastal basins of eastern Brazil, represent an area of high ichthyofaunal endemism. Despite being located in the middle of a forest that is extremely affected by anthropogenic actions (such as urbanization and deforestation), the Serra do Mar region also comprises several tourist attractions due to the contrast between stunning beaches and peaks that can reach up to 2,366m.

Living in a restricted area in the Serra do Mar between Rio de Janeiro and São Paulo States, the rare and the morphologically distinct catfish species Trichogenes longipinnis can be found in small streams and pools beneath waterfalls during the day- or night-time. Contrasting with most catfish species that are usually found associated with the river’s bottom, T. longipinnis individuals are active mid-water swimmers. These fishes can get really close when someone is inside the water watching them, even touching the observer. The adult males measure up to 14cm and the larger ones are solitary and territorial. They feed on aquatic and terrestrial arthropods (mostly insects and crustaceans) perceived visually and through the sensitive barbels², responsible for the tactile and chemosensory reception. Several authors identified different colouration patterns among some populations, a fact that usually indicates genetic differentiation and even speciation. Despite these divergent patterns, a recent work approaching molecular data and the geographic history of this species along its distribution area considered these phenotypically³ divergent populations as a single species. In this way, T. longipinnis populations can display diverse colouration patterns according to the stream these individuals inhabit. Trichogenes longipinnis was considered a vulnerable species in 2004 by the Brazilian Ministry of Environment (MMA), but it was further delisted. Considering it’s restrict distribution, the demographic decline suffered by several isolated populations within T. longipinnis, it would be of great value if efforts were made in the sense of preserving these species.

Taxonomic accounts: Order Siluriformes (catfishes) > Family Trichomycteridae > Genus Trichogenes > Species Trichogenes longipinnis

¹Endemism = when a species is unique to a defined geographic area.

²Barbels = a slender structure found nearby the mouth of different groups of fishes (catfishes, carps, sturgeons, zebrafishes etc.) that bear taste buds.

³Phenotype = an organism’s observable characteristics

Trichogenes longipinnis photo by Axel Katz

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Expedition Background

A biogeographic realm is a large spatial region that share a broadly similar biota in it's ecosystems. Currently, eight terrestrial biogeographic realms are recognized: Australasian, Afrotropical, Nearctic, Oceanic, Antarctic, Indo-Malayan, Neotropical and Palearctic.
The Neotropical region comprises the most diverse vertebrate fauna among all the biogeographic realms and extends from South America to Tropical North America and the Antilles. An estimate of 5160 species of freshwater fishes was made only for the South American Platform. These fishes are distributed through a wide variety of habitats such as rivers, waterfalls, floodplains, temporary pools and lakes. Not only the habitats are so diverse in this realm, but also the fish fauna that can be found there. From catfishes and tetras to stingrays, from miniaturized fishes measuring less than 10mm to giant ones measuring up to 3 meters (pirarucus), the Neotropical realm certainly can offer many insights and data to understand the history of several freshwater environments and the evolution of its fish fauna throughout time. My name is Elisabeth Henschel and I am the main coordinator of this blog. I'm a PhD student in Genetics with a master's degree in Biodiversity and Evolutionary Biology. My study focuses on the candirus, a group of freshwater parasitic catfishes that feed on larger fishes blood, skins, mucus and scales. I am a National Geographic Society Early Carreer Grantee since 2018, and this grant will allow me to do a 3-week expedition into the Amazon rainforest. Our team is composed by ichthyologists specialized in studying evolutionary biology using different approaches: colouration patterns, osteology, morphometry, molecular biology, geographic distribution and ecology. We are located at the Federal University of Rio de Janeiro, Brazil. Hope you can share all the moments of this journey with us!

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Thank you all for your kind comments! <3

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