Cockle transforming into a skeleton to visualize dying ecosystem.

Cockle Health Check: Are Portugal's Coastal Ecosystems at Risk?

Mira Elwood in Climate & Environment December 2025 • 4 min read.

"New research reveals surprising trends in trematode parasites, suggesting potential threats to Portugal's Ria de Aveiro."

Cockles, a popular seafood in Europe, play a crucial role in coastal ecosystems. These humble shellfish are a favorite food source for many and an indicator of environmental health. However, like all living things, they're susceptible to parasites, which can tell us a lot about the state of their environment.

Trematodes, a type of parasite, are common in cockles. Understanding how these parasites affect cockles can provide insights into the overall health of the ecosystem. Scientists recently investigated trematode communities in Cerastoderma edule cockles from Ria de Aveiro, Portugal, to assess the ecological status of this important area.

The study, conducted in 2012 and 2016, challenged the initial hypothesis that trematode communities would be spatially and seasonally diverse and stable over time. The results revealed a different story, highlighting the complex interactions within this coastal environment and raising questions about its long-term health.

The Parasite Puzzle: What the Study Revealed

Cockle transforming into a skeleton to visualize dying ecosystem.

The research focused on the spatio-temporal distribution of trematodes, common parasites in cockles, collected from several stations within the Ria de Aveiro lagoon. Scientists dissected cockles to identify and count the different trematode species present. By comparing data from different years and locations, they aimed to understand the dynamics of these parasite communities.

Key findings from the study include:

Unexpected Homogeneity: Despite initial expectations, the trematode communities showed a surprising degree of homogeneity across different locations and seasons. This suggests that environmental conditions within the Ria de Aveiro may be relatively uniform.
Interannual Heterogeneity: The biggest surprise was the significant difference in trematode communities between 2012 and 2016. This interannual variation was more pronounced than differences between locations or seasons, suggesting a shift in the ecosystem over time.
Loss of Diversity: The study revealed a worrisome decline in trematode diversity and prevalence between 2012 and 2016, potentially indicating a decline in overall biodiversity or changes in environmental conditions.

While trematode communities were relatively homogenous, the biggest shift came between 2012 and 2016. This interannual difference was more significant than any spatial or seasonal variations, indicating that something fundamental had changed in the ecosystem over this period.

Cockles as Canary: What Does This Mean for the Future?

The observed changes in trematode communities could signal broader environmental challenges in the Ria de Aveiro. The decline in trematode diversity and prevalence raises concerns about the overall health and resilience of the ecosystem.

Potential drivers of these changes include:

<ul> <li>Climate Change: Rising temperatures and altered weather patterns could be impacting parasite life cycles and host-parasite interactions.</li> <li>Overharvesting: Excessive harvesting of cockles could disrupt the ecosystem balance and affect parasite transmission.</li> <li>Pollution: Increased pollution from human activities could be weakening cockles and making them more susceptible to disease.</li> </ul>

About this Article -

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This article is based on research published under:

DOI-LINK: 10.1016/j.envres.2018.02.018, Alternate LINK

Title: Spatio-Temporal Variation Of Trematode Parasites Community In Cerastoderma Edule Cockles From Ria De Aveiro (Portugal)

Subject: General Environmental Science

Journal: Environmental Research

Publisher: Elsevier BV

Authors: Luísa Magalhães, Simão Correia, Xavier De Montaudouin, Rosa Freitas

Published: 2018-07-01

Everything You Need To Know

What are cockles and why are they important in this context?

Cockles, specifically *Cerastoderma edule*, are shellfish and a crucial part of the Ria de Aveiro's coastal ecosystem. They are a food source for many organisms and serve as an environmental health indicator. The presence and health of cockles can reveal much about the overall health and stability of the area. They are susceptible to parasites, making them an excellent subject for study.

What are trematodes and why are they being studied?

Trematodes are a type of parasite frequently found in cockles. Studying these parasites provides insights into the Ria de Aveiro's ecosystem health. Analyzing the trematode communities within the *Cerastoderma edule* cockles helps researchers understand the environmental conditions and the impact of changes over time. Monitoring trematode populations can highlight broader ecological problems, such as declining biodiversity or environmental shifts.

Why was the Ria de Aveiro chosen for this research?

The Ria de Aveiro is a vital coastal ecosystem in Portugal. The research focused on this location to assess its environmental health through the analysis of trematode communities in cockles. The study's findings, like the loss of trematode diversity, suggest that the Ria de Aveiro could be facing environmental challenges. This location was chosen because it is an important ecosystem and the health of its inhabitants are vital to its future.

What were the key findings of the research on trematodes?

The study revealed surprising changes in the trematode communities within *Cerastoderma edule* cockles. Scientists initially expected diverse and stable communities. However, they found unexpected homogeneity across different locations and seasons. More significantly, the study found interannual heterogeneity with a significant difference in trematode communities between 2012 and 2016, including a decline in diversity and prevalence, indicating potential shifts in environmental conditions and a decline in overall health.

What do these changes in trematode communities mean for the future of the Ria de Aveiro?

The changes observed in the trematode communities, such as the loss of diversity and prevalence, could signal broader environmental challenges for the Ria de Aveiro. This raises concerns about the overall health and resilience of the ecosystem. The observed changes suggests potential decline in biodiversity or shifts in environmental conditions within the Ria de Aveiro, highlighting the need for further investigation and conservation efforts to preserve this important coastal area.