MMOI - The Mar Menor Oyster Initiative
Knowledge and Tools for a Future Oyster Restoration Action

Wild flat oysters on the rocky bottoms of the Mar Menor islands (Mar Menor, Spain)

MMOI – The Mar Menor Oyster Initiative

This initiative is supported by scientists belonging to different research institutions (Spanish Institute of Oceanography, IEO-CSIC; University of Basque Country, UPV-EHU; Institute of Marine Sciences, ICM-CSIC; Dalhousie University, Halifax, Canada) and led by the Oceanographic Center of Murcia (IEO-CSIC).


The Mar Menor (37°48′ 52.847″ N, 0° 47′ 2.431″ W) is a hypersaline protected lagoon located in the southeast of Spain. It is one of the largest coastal lagoons in the Mediterranean region, as well as in Europe. The lagoon average depth is 3.6 m with an extension of 135.5 km2. A sandbar called La Manga separates the lagoon and the Mediterranean Sea with five channels connecting both water bodies. Traditionally, the Mar Menor has been an oligotrophic and hypersaline (53-70 ups) ecosystem with sedimentary bottoms dominated by seagrasses but since the 70s salinity decrease until 42-45 psu due to the dredging of one of the channels, which increased water exchange with the Mediterranean. As a result, the flat oyster and other species were able to colonize the lagoon and a population of 135 million individuals developed during the 90s. This population has been reduced in last decades so that today only isolated individuals are observed near the rocky bottoms around the islands of the lagoon.

Human activities around the lagoon (mining, intensive agriculture and uncontrolled tourism development) have led to a deterioration (eutrophication) of the environmental quality of its waters which collapsed in 2015 when a green soupdeveloped throughout the Mar Menor causing the death of bottom macrophytes. Massive phytoplankton blooms have occurred since then, in addition to episodes of anoxia that have caused massive mortality of fishes and crustaceans. Lately the deterioration of the lagoon is shown by macroalgae blooms.

MMOI promotes the restoration of flat oyster populations as a nutrient bioextraction solution thus contributing to the recovery of the lagoon’s environmental quality and assessing the potential for oyster aquaculture in the area.

MMOI aims to:

  • gain KNOWLEDGE on the feeding physiology of the oyster and its nutrient extraction capability to recover eutrophic environments.
  • develop the necessary TOOLS for a future oyster restoration action within the framework of a comprehensive plan for the restoration of the lagoon.
  • promote oyster restoration as a best management practice through OUTREACH and society engagement in Mar Menor.

Several projects are being developed within the framework of MMOI:

  • RemediOS projects 
    ( aim to carry out proofs of concept on the necessary techniques to be applied in future bioremediation actions: oyster seed production in hatchery, nursery in salines channels, remote setting, oyster reefs and suspended oyster culture. Along with these scientific actions, RemediOS includes environmental education, administrative and governance actions, as well as blue economy actions based on the oyster. RemediOS is funded by the Biodiversity Foundation (Spanish Ministry for Ecological Transition and the Demographic Challenge, MITERD), through the Pleamar Program, co-financed by the European Maritime and Fisheries Fund.
  • RESALAR project 
    ( aims to restore and regenerate coastal areas of the Mar Menor and its biodiversity, as the Marchamalo saltponds, to reduce the impact of human activity, strengthen the resilience of the coastline against climate change and improve and increase the ecosystem services they provide to society. The salt facilities (supply channels) serve as growing places for the seed produced in the ReemdiOS hatchery. The project is coordinated by the NGO, ANSE Foundation, and is supported by the Biodiversity Foundation (MITERD) within the framework of the Recovery, Transformation and Resilience Plan (PRTR), funded by the European Union – NextGenerationEU and is linked to the Framework of Priority Actions for the recovery of the Mar Menor of the Ministry for Ecological Transition and the Demographic Challenge.
  • MIToYSTER project 
    aims to assess the effect of chemical pollution on the life cycle of the Mar Menor flat oyster and its nutrient bioextraction capacity. Generally, eutrophication in coastal ecosystems is often accompanied by chemical pollution due to the same human activity that causes eutrophication. The most worrying pollutants in the Mar Menor are heavy metals due to mining activity and organic pollutants (herbicides, pesticides and pharmaceuticals) due to agriculture and touristic development. The project is funded by the State Research Agency of the Spanish Ministry of Science. In addition to the IEO-CSIC, the universities of La Coruña and the Basque Country are participating.
Eyed-larvae produced at the RemediOS hatchery (IEO-CSIC, Murcia, Spain)
Oyster spat produced at the RemediOS hatchery (IEO-CSIC, Murcia, Spain)
Juvenile flat oysters produced in the RemediOS Hatchery and growing in the San Pedro del Pinatar salines channels (Mar Menor, Spain)
RemediOS Hatchery at the Spanish Institute of Oceanography (IEO-CSIC, Murcia, Spain)


Marina Albentosa
Senior Researcher
Spanish Institute of Oceanography (IEO-CSIC, Spain)