Wetlands and Mangroves: Interconnecting Knowledge for Environmental Management

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November 13, 2025

Aquatic Vegetation Cover in the Pajarales Complex,

Ciénaga Grande de Santa Marta, Colombia, May 2024 – Oct 2025

13 Nov 2025

Horst Salzwedel

Abstract

The rapid expansion of aquatic vegetation in the Ciénaga Grande de Santa Marta (CGSM) has raised growing concern among local communities and governmental institutions, particularly in the Complejo Pajarales near Nueva Venecia. This study quantifies the monthly surface area covered by submerged and floating macrophytes—primarily Hydrilla verticillata and Eichhornia crassipes—between May 2024 and October 2025 using Sentinel-2 satellite imagery processed in Google Earth Engine. Monthly median NDVI composites were generated from 5–16 cloud-free scenes per month, and pixels with NDVI ≥ 0.40 were classified as vegetated. Within the 1,204-ha area of interest, vegetation cover increased dramatically from approximately 15 ha in October 2024 to 690 ha in October 2025, representing a forty-six-fold expansion. Spatial patterns show an initial concentration near the stilt village of Nueva Venecia, followed by progressive eastward and southeastward infilling of the basin. This rapid proliferation coincides with a freshening of lagoon waters below 10 PSU, a threshold that favors both Hydrilla and attached Eichhornia. The results document a pronounced and ongoing ecological transformation within Pajarales and highlight the usefulness of high-resolution, cloud-robust NDVI composites for tracking macrophyte dynamics in tropical coastal wetlands. The full processing workflow and annotated code are publicly available through the project repository (DOI included in manuscript).

Keywords: Coastal wetlands, Hydrilla verticillata, Invasive species, NDVI

20251113_Aquatic-Vegetation-Cover-in-the-Pajarales-Complex-Cienaga-Grande-de-Santa-Marta-Colombia-May-2024-Oct-2025-1.docx

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Daniel Henryk Rasolt

Interdisciplinary and intercultural researcher and writer. Founder and Chief Editor of The InterPlex.

October 20, 2025

Vamos adelante

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Paulo Murillo

Land use and remote sensing scientist. Assistant professor - Universidad del Tolima.

September 30, 2025

Actualmente es necesaria la intervención de la CGSM en dos líneas. La primera en procesos de restauración asociados al mantenimiento de canales y conservación del manglar. La segunda a la presencia de especies introducidas que eventualmente se convertirán en invasivas y que tienen efectos negativos sobre la vegetación nativa y sobre el bienestar de los pobladores ya que no permiten la pesca y al pudrirse causan problemas de salud. El uso de imágenes de satélite y de drones es el primer paso para conocer su extensión y evaluar estrategias de erradicación.

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Jose Ernesto Mancera Pineda

Marine biologist with a focus on mangroves and coastal marine ecology. Research professor at the National University of Colombia. Advisor for The InterPlex.

September 29, 2025

Motivados por el interés de utilizar el conocimiento existente para superar problemas ambientales identificados en humedales costeros de Colombia, hemos decidido conformar un grupo de trabajo. Abordaremos inicialmente la reserva internacional de biósfera Ciénaga Grande de Santa Marta, localizada en el Caribe colombiano. Un sistema socioecológico muy complejo de alto interés social, del cual existe mucha información, cuyo análisis permitirá consolidar propuestas de acción. Buena parte de la información para el análisis es de acceso abierto (cgsm.cemarin.org).

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About

Hybrid

Eng: The articulation of knowledge, expertise, and experiences from different social actors is essential for the identification of alternatives and solutions for the management of natural heritage, its sustainable use, and equitable exploitation. In this intergroup we focus on wetland and coastal socio-ecological systems, in Colombia and beyond, but invite those with diverse backgrounds, perspectives and expertise, to join.

Esp: La articulación de conocimientos, pericia y experiencia de diferentes actores sociales es esencial para la identificación de alternativas y soluciones para la gestión del patrimonio natural, su uso sostenible y su explotacion equitativo. En este intergrupo nos centramos en los los sistemas socioecológicos costeros y de los humedales, tanto en Colombia como en el resto del mundo, pero invitamos a unirse a personas con diversos antecedentes, perspectivas y experiencia.

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Group Creator(s)

Jose Ernesto Mancera Pineda

Marine biologist with a focus on mangroves and coastal marine ecology. Research professor at the National University of Colombia. Advisor for The InterPlex.

September 28, 2025

August 5, 2026

Mangrove Commons: Biocultural Heritage in the Afro-Colombian Pacific

For Afro-Pacific communities, biodiversity and cultural heritage are not separate concerns—protecting one means protecting the other. Their interrelation makes a compelling case for biocultural heritage as a framework for research, governance, and conservation.

Rowan Glass

Contributors

December 15, 2025

The Role of Assertive Communication in the Effectiveness and Sustainability of Nature-Based Solutions (NbS)

In the context of risk management and in the face of environmental and economic challenges such as climate change, coastal erosion, water insecurity, and the accelerated loss of biodiversity, among others, the concept of Nature-based Solutions (NbS) has emerged. Over the past decade, this appealing concept has been consolidated as an integrative approach that seeks to address socio-environmental challenges through the sustainable management of socio-ecological systems. The United Nations Environment Assembly defines NbS as “actions that protect, sustainably manage, and restore natural or modified ecosystems to effectively and adaptively address societal challenges, simultaneously providing benefits for human well-being and biodiversity.” In this way, NbS represents a paradigm shift from traditional solutions based exclusively on grey infrastructure, which are now insufficient in facing many large and complex contemporary challenges. The relevance of NbS resides in their capacity to generate multiple, synergistic benefits through ecosystem services and the strengthening of socio-ecological resilience. This approach recognizes the interdependence of nature and culture, and much of its success depends on how communities perceive and acknowledge the multiple benefits socio-ecological systems provide for human well-being. Therefore, NbS must emphasize the need for participatory, equitable, and inclusive processes to ensure their legitimacy and long-term sustainability. NbS encompass actions for the protection, restoration, and sustainable management of ecosystems. Although they offer multifunctional and cost-effective benefits, their implementation faces diverse challenges. Several international frameworks acknowledge NbS as priority strategies to confront climate change and biodiversity loss, promoting guidelines for their adoption at different scales. Among these frameworks are the United Nations Framework Convention on Climate Change (1992), the Convention on Biological Diversity (1992), the Sendai Framework (2015–30), and the Paris Agreement (2015). However, it is not enough to only secure financing or display technical feasibility. It is also necessary to establish a coherent legal framework, generate open and...

PeriodicoUNAL-090623-03-am - Mancera-cut

Jose Ernesto Mancera Pineda

Contributors

November 10, 2025

The Social-Life of the Pixel in Land System Science

Earth Observation technologies are becoming increasingly valuable for understanding our changing world. They are also critical for formulating policies to protect ecosystems and support local communities. The availability of imagery taken from satellites, airplanes, and drones offers opportunities to detect deforestation, glacier melting, crop productivity, hurricane alerts, ocean temperatures, and much more. These applications have become wide-spread and are commonly featured in the news and on social media; an informed public can now be acutely aware of the significant effects that humans have on the landscape. However, other processes of land use change are too complex to be detected and understood solely from space. For example, detecting rich minerals, tracking illicit land activities (e.g., coca farming), and monitoring water salinity. For these and other complex land changes, the imagery itself might not be enough to understand the processes shaping these changes in the landscape. New ways of addressing these are needed. About 26 years ago, Jacqueline Geoghegan and her co authors wrote a chapter in the book People and Pixels: Linking Remote Sensing and Social Science, titled “Socializing the Pixel and Pixelizing the Social in Land-Use and Land-Cover Change.” This chapter was a pioneering step forward in extracting more information from images and linking them with the social processes behind them. It helped me during my PhD studies and subsequent research to develop a strategy for connecting quantitative data from pixels with social mechanisms that impact land change. But how do these two approaches work together? The full Interdialogue with Paulo Murillo. The role of classification in traditional land use science relies on how effectively we can classify elements on the land surface. Classification is the most relevant task in remote sensing. We want to classify or differentiate between forests and agricultural fields or among diverse types of crops using...

Paulo Murillo

Contributors

February 17, 2025

The Challenges and Socio-Ecological Importance of Delimiting Colombia’s Wetlands

As an official in Colombia’s Ombudsman’s Office, I was a member of an interdisciplinary team that documented the issues faced by artisanal fishermen. I soon became aware of a serious widespread problem which receives minimal public attention. Those who engage in fishing activities in lentic inland waters, such as lakes, ponds and “ciénagas”, often share a common concern: the waters on which they depend have not been properly demarcated. In other words, the delineation process, known locally as “deslinde,” has not been completed to define the boundaries between ecosystems belonging to The Colombian State and those areas where private property rights apply. This is not a recent issue, on the contrary, this represents a long-standing information gap. The State does not have clear data in regards to delimited wetlands and academia has not extensively explored the problems associated with this process. The consequences of this lack of information are severe. Some of the most well-known include the appropriation of amphibious shores (floodplain lakes referred to in Colombia as “playones”), the loss of fauna and flora due to changes in land use, an increase in property concentration, and the abandonment of collective practices in flood-prone areas. This situation particularly affects the ciénagas, which are wetlands that play a crucial role in mitigating rising water levels during periods of heavy precipitation. They also help to regulate river flows and support the reproductive cycles of fish. Furthermore, there has not been a participatory process to delimit the ciénagas, where the limits of the wetlands are decided with the support of the local population. It is essential to recognize that rural communities are an integral part of these ecosystems, but the Colombian State fails to acknowledge the interdependence that exists between wetland ecosystems and artisanal fishermen. These fishermen, in many cases, have lived in...

Juan Manuel Quinche

Contributors

October 26, 2024

Restoring the Ciénaga Grande de Santa Marta: Reversing a Century of Colombian Tragedy

Can science and tradition finally help heal the region’s peoples and bring balance to its biodiversity-rich waters and mangrove forests? This article was originally published by The Revelator

Daniel Henryk Rasolt

Contributors

September 14, 2024

Colombian fishers are fighting for their rights and protection of vital wetlands

Interconnected socio-ecological issues threaten the ecosystems of the Mompós Depression Wetlands and the traditional fishing communities who rely on and safeguard them.

Daniel Henryk Rasolt

Contributors

Paulo Murillo – Land Use Science, Remote Sensing and Socializing the Pixel

Ernesto Mancera: Nature-Based Solutions, Mangroves and the Cienaga Grande de Santa Marta

Rafael Hurtado: Sociophysics and Complex Systems

Juan Manuel Quinche: Ciénagas, artisanal fishermen, socio-ecological systems and the demarcation of Colombia’s wetlands

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Members

Daniel Henryk Rasolt

Interdisciplinary and intercultural researcher and writer. Founder and Chief Editor of The InterPlex.

September 28, 2025

Horst Salzwedel

September 28, 2025

Jose Ernesto Mancera Pineda

Marine biologist with a focus on mangroves and coastal marine ecology. Research professor at the National University of Colombia. Advisor for The InterPlex.

September 28, 2025

Juan Manuel Quinche

Anthropologist. Researcher on Human and Environmental Rights

September 28, 2025

Luiz Drude de Lacerda

Brazilian Biologist and Biogeochemist. Professor Titular; Univ. Federal do Ceará

September 28, 2025

Omar Guarín Villazón

Community leader, artisanal fisherman, President of COMENALPAC

September 28, 2025