Jellyfish Nets vs. Ecosystem: Mar Menor

Jellyfish in the Mar Menor, Costa Cálida

Navigating the Jellyfish Dilemma: Striking a Balance in Mar Menor. Photo credit:

AS the tourist season kicks off in Mar Menor, the coastal towns are grappling with a surge in jellyfish populations. Cartagena, San Javier, and San Pedro del Pinatar have requested the installation of anti-jellyfish nets to protect their bathing areas. However, the Scientific Advisory Committee of Mar Menor advises against these nets due to their potential negative impact on the ecosystem. Los Alcázares, on the other hand, has ruled out the use of nets, except in cases of massive jellyfish proliferation. Here we will have a look at the arguments for and against the installation of anti-jellyfish nets and the current state of the Mar Menor.

The Call for Anti-Jellyfish Nets

Despite scientific advice to the contrary, Cartagena, San Javier, and San Pedro del Pinatar have urged the regional government to install traditional anti-jellyfish nets. Their primary concern is to prevent jellyfish from densely congregating in bathing areas and causing inconvenience to holidaymakers. San Pedro del Pinatar, in particular, made the request last week after experiencing occasional jellyfish proliferation on its beaches.

Scientific Opposition to Nets

The Scientific Advisory Committee of Mar Menor strongly opposes the installation of anti-jellyfish nets, a stance they have maintained for several years. According to their report, these nets act as barriers, causing the death of some jellyfish species. The accumulation of organic matter within the nets obstructs water currents, leading to beach siltation, foul odours, and a depletion of dissolved oxygen. Additionally, the committee highlights that the two most common species in the lagoon, Cotylorhiza tuberculata, and Phyllorhiza punctata, are non-stinging. While a proliferation of these species is expected this summer, it is unlikely to reach the levels observed in 2011 and 2012.

Ecosystem Impact and Alternative Measures

The scientific committee warns against the mass collection of jellyfish, as it is ineffective due to the large populations and high fertility of these organisms. Moreover, accidental capture of seahorses may occur during collection efforts. Scientists emphasise that jellyfish play a crucial role in the ecosystem by preying on phytoplankton and eliminating excess nutrients. Therefore, interfering with their natural presence can have unintended consequences.

State of the Mar Menor

Jellyfish populations in the Mar Menor have been a recurring phenomenon since the mid-1990s, with fluctuations in their intensity over time. In 2016, their presence diminished due to water darkening, which prevented light from reaching the seabed and resulted in jellyfish mortality. However, in recent years, jellyfish populations have shown a gradual recovery. The lagoon currently hosts species such as Aurelia aurita, Cotylorhiza tuberculata, Rhizostoma pulmo, and Phyllorhiza punctata. The levels of nutrients in the water are within the regulated parameters, except in specific areas affected by runoff and leachate.

The controversy surrounding the installation of anti-jellyfish nets in Mar Menor highlights the clash between the demands of local town councils and the scientific advice provided by the advisory committee. While the councils seek to protect bathing areas from jellyfish, experts argue that these nets disrupt the ecosystem and have limited effectiveness. As the Mar Menor enters the tourist season, it is essential to balance the interests of beachgoers with the long-term ecological health of the lagoon. Ongoing monitoring and research will be crucial in understanding and managing jellyfish populations in the future.

Let us know what you think in the comments below, nets or no nets?$m122,70

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Written by

Catherine McGeer

I am an Irish writer who has been living in Spain for the past twenty years. My writing centers around the Costa Cálida. As a mother I also write about family life on the coast of Spain and every now and then I try to break down the world of Spanish politics!