A pact across continents or how ethical volunteering and 40 years of otter science are rewriting conservation

Bridging 40 years of otter science and global eco-volunteering, Projeto Lontra and Estuarine Management and Technologies invite research for a topical collection.

Guest blog post by Dr. Oldemar de Oliveira Carvalho Junior

After 40 years of protecting the Neotropical otter, Projeto Lontra is opening a new chapter. We are calling on researchers to contribute to the “Otters as Bioindicators of Estuarine Health” Topical Collection in the journal Estuarine Management and Technologies, bridging the gap between long-term field observations to innovations in the field.

This call is a natural evolution of a story that began in January 1986. On the wild shores of Peri Lagoon in southern Brazil, my father and I stood beneath the canopy of the Atlantic Forest and dreamed aloud: What if we could protect this place by protecting its most elusive guardian, the Neotropical otter?

That dream became Projeto Lontra. For forty years, we have walked these shores not as distant scientists, but as neighbors, listening to the water, reading the spraints, and learning from fishers who’ve known these lagoons longer than any journal has existed.

But conservation cannot be a solitary act. And so, in the early 2000s, a quiet revolution began. People of all ages from France, Germany, and beyond started arriving, not as tourists, but as eco-volunteers through different international organizations, such as Cybelle Planète. They came not to “save” us, but to stand with us.

Eco-volunteers installing a trap camera inside an otter cave. Credit to Projeto Lontra and Instituto Ekko Brasil

This is the heart of our partnership: reciprocity, not rescue.

More Than Volunteering. A Model of Shared Stewardship

Cybelle Planète does not sell travel; rather, it cultivates responsibility. Their volunteers spend weeks living alongside our team, collecting spraints at dawn, mapping latrines, teaching in local schools, and planting native trees. They return home not just with photos, but with data that feeds into global assessments, and with a transformed understanding of what it means to care for a shared planet.

As one Cybelle Planète coordinator once told me:

We don’t promote travel. We promote responsibility.

This ethos mirrors our own. In Brazil, conservation has too often been framed as a deficit, something we lack, something others must fix. But Projeto Lontra has always believed that local knowledge is expertise and long-term presence is data. Our 40-year dataset, born from patience, not satellites, is proof.

  • eco-volunteer near a lagoon

Now, this partnership takes on new scientific weight as a cornerstone of the Scientific Journal Estuarine Management and Technologies and its Topical Collection Otters as Bioindicators of Estuarine Health. But rather than spotlight methods or metrics, we want to spotlight people and the relationships that make science meaningful.

Voices of the Collaboration

To truly reflect the spirit of this alliance, we invited key voices to share their vision:

Nosso papel não é promover viagens, mas cultivar a responsabilidade – de longo prazo, recíproca e fundamentada na confiança entre os atores locais da conservação e os cidadãos internacionais.

(Our role is not to promote travel, but to foster responsibility – long-term, reciprocal, and grounded in trust between local conservation actors and international citizens.)

Celine – Cybelle Planète Leadership – Vision Statement Placeholder

We are reminded that research and materials produced outside traditional commercial or academic sectors can be just as important.

For over 30 years, the Bulletin has amplified voices from the Global South that commercial journals overlook. Projeto Lontra’s legacy reminds us that grey literature is often golden and that true bioindicator science grows from the ground up.

Dr. Arno Gutleb, IUCN Otter Specialist Group Bulletin

A Call to Join the Movement

Neotropical otter (Lontra longicaudis). Photo credit to: Projeto Lontra and Instituto Ekko Brasil

This isn’t just a story about otters. It’s about a new way of doing conservation:

  • Municipalities can use tools like the Otter Health Index (OHI) to monitor their estuaries without million-dollar labs.
  • Researchers can contribute to a truly global bioindicator framework that centers tropical species.
  • Eco-volunteers can join hands-on programs that generate real data while fostering cross-cultural understanding.

And everyone – scientist, student, and citizen – can engage with the “Otters as Bioindicators” Topical Collection to help shift the narrative from extraction to exchange, from hierarchy to humility.

Because in the end, the otter teaches us this: ecosystems are woven from connection. So too must be our efforts to protect them.


Explore the Topical Collection: Otters as Bioindicators – EMT
Learn about volunteering with Cybelle Planète: www.cybelle-planete.org
Read the foundational synthesis paper: Otters as Bioindicators of Estuarine Health

Otters as ocean doctors: how a 40-year watch on Brazil’s coasts reveals hidden threats to estuaries

Neotropical otters are key for estuarine health, providing insights into ecosystem integrity and pollution impacts.

Guest blog post by Dr. Oldemar de Oliveira Carvalho Junior

For four decades, we’ve been quietly watching otters along the southern coast of Brazil. Not just because they’re charismatic and playful, but because they are among nature’s most honest diagnosticians. Just like a doctor checks your pulse, blood, and behavior to assess your health, scientists can use otters to monitor the condition of estuaries, those vital transition zones where rivers meet the sea.

Published in Estuarine Management and Technologies, our new study, ‘Otters as Bioindicators of Estuarine Health,’ synthesizes 40 years of field data from from Projeto Lontra in Brazil’s Peri Lagoon, along with global ecological research. The findings reinforce the role of semi-aquatic mammals as “living sensors” of ecosystem integrity.

This study is part of the topical collection: Otters as Bioindicators of Estuarine Health: Innovations in Monitoring and Management from Tropical Coastal Brazil

Why otters and not another animal?

Neotropical otter (Lontra longicaudis). Photo credit to: Projeto Lontra / Instituto Ekko Brasil

Otters sit at the top of the food chain in estuaries. They need clean water, healthy fish populations, connected habitats, and safe denning sites. If any of these elements falter, otters are among the first to respond, with fewer sightings, changes in their diet, or markers of disease.

While a water sample offers only a fleeting snapshot, otters aggregate environmental signals across time and space.

Neotropical otter with a cub. Photo credit to Projeto Lontra / Instituto Ekko Brasil

In fact, their very presence, or absence, tells a story. In regions where Atlantic Forest fragmentation has severed the connection between land and water, otter sightings have plummeted by 30% in just a decade.

This isn’t just a loss of biodiversity; it’s a warning for everyone downstream. Fewer otters mean degraded waterways, disrupted food webs, and weakened natural buffers against floods and erosion.

A “living record” of pollution

Neotropical otter (Lontra longicaudis) feeding on fish. Video credit to: Projeto Lontra / Instituto Ekko Brasil

The diet of otters consists of 70-80% fish, as well as crabs and other aquatic animals. As they consume prey, they also accumulate pollutants, like heavy metals, microplastics, and industrial chemicals, that have built up in those animals. Their bodies effectively become archives of contamination.

Think of an otter as a biological hard drive: by analyzing its scat (feces), we can reconstruct what pollutants are moving through the estuary, even if they’re invisible to the naked eye.

For instance, in Brazil, we’ve found microplastic fibers in otter droppings from protected lagoons, proof that no coastal system is truly isolated from human impact.

The tropical knowledge gap

Neotropical otter. Photo credit to: Projeto Lontra / Instituto Ekko Brasil

Globally, over 70% of otter research focuses on temperate species like the Eurasian or sea otter. Meanwhile, the Neotropical otter (Lontra longicaudis) receives less than 4% of scientific attention, despite inhabiting the world’s most biodiverse and threatened estuaries.

This imbalance in the research poses a great conservation risk. Tropical estuaries face unique pressures: rapid urbanization, mangrove deforestation, and climate-driven sea-level rise. Without focused research, we risk managing these ecosystems with tools designed for entirely different environments.

Our work aims to close this divide, establishing the Neotropical otter as a key indicator to drive evidence-based conservation across the Global South.

Land-based diseases in aquatic sentinels

Video from trap camera of two Neotropical otters in a shelter. Video credit to: Projeto Lontra / Instituto Ekko Brasil

One of our most striking findings showed that 66% of otters tested positive for Toxoplasma gondii – a parasite shed only by domestic cats. How does a land-based pathogen end up in an aquatic mammal? The answer is through runoff.

The rain washes cat feces from the streets, gardens, and informal settlements into rivers and lagoons. This reveals a sobering truth: even within protected areas, otters are exposed to threats originating far inland. To protect these sentinels of ecosystem health, we must implement integrated management strategies that address sewage overflow, urban runoff, and domestic animal impact.

What comes next?

Neotropical otter inside a shelter. Video credit to: Projeto Lontra / Instituto Ekko Brasil

We’re finalizing the Otter Health Index (OHI), a low-cost toolkit for municipalities, NGOs, and community groups to monitor estuaries using simple metrics: spraint frequency, habitat connectivity, contaminant screening, and local knowledge. It’s designed for places with limited labs but rich ecological insight.

After 40 years of observing otters, we’ve learned this: protecting them isn’t just about saving a species. It’s about safeguarding the intricate web of processes that sustain clean water, fisheries, flood resilience, and human well-being.

Otters aren’t just inhabitants of our estuaries; they are their guardians. If we listen to what they’re telling us, we’ll know exactly what these ecosystems need to survive and thrive.

Original sources:

Carvalho Junior, O., Bez Birolo, A., Tosatti, M., Haddout, S., Ljubenkov, I. and Jayachandran, P.R. eds., (n.d.). Otters as Bioindicators of Estuarine Health: Innovations in Monitoring and Management from Tropical Coastal Brazil. PEstuarine Management and Technologies. doi:https://doi.org/10.3897/emt.coll.317


Birolo, A.B., Tosatti, M., Junior and Assiya Haddout (2026). Otters as bioindicators of estuarine health: Scientific gaps, field-based insights, and a framework for future research. Estuarine Management and Technologies., 3, pp.65–78. doi:https://doi.org/10.3897/emt.3.185117.

Estuarine Management and Technologies now accepted in the Directory of Open Access Journals

Following rigourous assessment, the journal has successfully demonstra compliance with global standards of ethics, transparency and quality.

Estuarine Management and Technologies now accepted in the Directory of Open Access Journals: a key scientific index, internationally renowned as a trusted quality filter for open-access journals.

Having EMT accepted by DOAJ means that the journal has successfully passed a thorough assessment concerning its compliance with global standards of ethics, transparency and quality. The evaluation conducted by DOAJ includes an examination of the journal’s peer-review processes, editorial governance, transparency (e.g. publication fees, funding) and ethical policies (e.g. plagiarism, conflicts of interest). For many institutions, funders and libraries, DOAJ is seen as a credibility signal that distinguishes legitimate journals from predatory and/or low-quality ones.

The journal’s recognition comes only two years after the journal was launched as part of a promising joint initiative between a team of scientists headed by Dr. Soufiane Haddout (Ibn Tofail University, Morocco) and the open-access scientific publisher and technology provider Pensoft.

All articles published in the journal are already indexed and browsable on DOAJ. Future papers will be fetched by the platform right after they are published in EMT due to the automated data export workflows powered by Pensoft’s in-house ARPHA Publishing Platform.

Since early 2024, the journal has been seeking to support the exchange of research findings and ideas related to the conservation and sustainable management of estuarine ecosystems by utilising new technology and novel approaches. To further support scientists from around the globe, the journal operates under a Diamond Open Access model, meaning that neither publishing, nor reading incurs charges for authors or readers, respectively.

Today, EMT welcomes studies from a wide spectrum of disciplines, including physics, chemistry, geology, biology, and hydrology, with a focus on interdisciplinary, multifaceted approaches and holistic perspectives. A unique feature of the journal is its diverse range of publication types, such as Education & Communication, Estuarine scientists and Video paper in 180s.

“We are proud to announce that Estuarine Management and Technologies has achieved indexing in the Directory of Open Access Journals: our first significant milestone on the path to greater visibility and impact in the global scholarly community,”

said Dr. Soufiane Haddout, on behalf of the journal’s Editorial Board.

This crucial first step in our indexing journey validates EMT’s commitment to rigorous, transparent, and immediately accessible research on technological innovations for estuarine research, management, and conservation. DOAJ inclusion enhances discoverability for our authors’ work and strengthens our role in advancing interdisciplinary solutions for these vital ecosystems. We are grateful to our authors, reviewers, and the Pensoft team,

he added.