The mangroves of the Galapagos Islands are fish nurseries

May 28, 2021 00:00
Paola Gavilanes

Golden stingrays photographed in divided mangroves during investigation. Photo: Courtesy Pelayo Salinas / Charles Darwin Foundation

The mangroves in the Galapagos Islands are special; there is less mud ,and the trees are smaller and set apart from each other. In the rest of the country, the mangroves are dense and the trees are much taller.

It was those precise characteristics, that caught the attention of Denisse Fierro Arcos, marine biologist and scientist at the Charles Darwin Foundation, and that motivated her to lead an investigation to find out if those ecosystems provided the same type of services.

These complex root systems are known to serve as hiding places for baby fish and also to provide a food source during the critical stage of their development.

After collecting numerous samples over the course of a month and a half, and through their analysis, it was found that these mangroves do in fact serve a function as nurseries for a great variety of fish; they also provide them with a habitat throughout their life, even during their juvenile stage.

This is [the location] where they hide from their predators. On that list are everything from snapper and cod to sharks and various species of stingrays .

Fierro Arcos, 35, who currently lives in Australia, points out that many of these fish have real, local socio-economic importance. Hence the need to protect mangroves.

Currently, under the zoning of the Galapagos Marine Reserve which has been in force since 2001, only 5% of the mangrove areas on the islands receive full protection from extractive activities. This precise amount serves to comply with the different investigations. The rest is open to fishing and human activities such as tourism .

In this research, the marine biologist worked directly with a group of scientists, including her supervisor, as this study is part of her master’s thesis. They visited a total of 28 mangrove areas on six islands of the Ecuadorian archipelago.

They used a combination of two sampling methods: remote stereo cameras and underwater visual censuses to describe the diversity and abundance of fish that live among the roots of the mangroves . This is stated in the report that has already been released and published in volume 664 of the specialized journal Marine Ecology Progress Series.

35,029 fish belonging to 93 species, 67 genera and 36 families were identified [in the mangroves]. Pomacentridae, Mugilidae, Haemulidae, and Lutjanidae were the most common families. Juveniles made up 43% of the fish. 30 species are important to local artisanal fisheries, while 80% of the species are associated with reef habitats .

That “suggests that mangroves in Galapagos can provide breeding habitats for economically valued species,” the report reads.

The marine biologist comments that mangroves are little studied and that also prompted her to undertake the research, which is based on previous work to expand the understanding of the importance of these habitats and contribute to the development of strategies and policies that can protect these areas in a more effective way.” Fishermen benefit from these areas which are protected .”

With the study, for example, it was learned that to the west of the islands of the archipelago there is a greater concentration of species. “That may be one of the areas that needs a lot more protection, while the other areas could be a bit more open.”

Another conclusion reached is that certain areas could be closed when the fish are spawning. “There are ways to manage that, so that people can continue to work, have access to food, but at the same time take care of those mangroves.”

Protecting the place where sharks and different species of manta rays grow and develop is also necessary to promote local tourism, as many people come to the Galapagos Islands just to see them.

The results of this research have already been delivered to the Galapago National Park. Its members are the ones who decide if they take action based upon the information and how they are going to use the information or implement it.

Read the original coverage from El Comercio at https://www.elcomercio.com/tendencias/ambiente/manglares-islas-galapagos-guarderias-peces.html


Read additional coverage from El Universo at https://www.eluniverso.com/larevista/ecologia/los-manglares-de-las-islas-galapagos-son-ecosistemas-clave-para-gran-diversidad-de-especies-de-peces-nota/


Informing and sharing news on marine life, flora, fauna and conservation in the Galápagos Islands since 2017
© SOS Galápagos, 2021

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