The life of fishes at the world’s smallest and isolated tropical island

foto_post_penedosReef fish communities have been intensely studied on large reef systems in the Caribbean Sea and Western Pacific regions, whereas communities on small and remote oceanic islands are still poorly understood. Logistical constraints imposed by remoteness limit fieldwork time and increase research costs. However, since environmental impacts on these previously pristine localities are increasing, there is an urgent need to learn how these isolated communities are structured. Isolated islands have been long known as natural laboratories for ecology and evolution because they are ecologically simpler than larger continental habitats. In a study published this week, Osmar Luiz, Diego Barneche and their colleagues take the ecological simplicity of islands to the extreme by investigating the factors affecting the reef fish community of the smallest remote tropical island in the world: the St. Peter and St. Paul’s Archipelago in the equatorial Atlantic Ocean, on the mid-Atlantic ridge. The archipelago is only 400m across at its greatest extent and has the most depauperate reef fish assemblage known for a single tropical island, with roughly 60 species recorded. Ecological communities are often structured by a complex combination of abiotic and biotic factors. In the St. Peter and St. Paul’s Archipelago, however, none of the biotic variables studied appear to be important, probably because of less competition for resources due to low species richness and a large proportion of generalist species. On the other hand, depth was the most important driver of species abundance, biomass and diversity. The study finds that the island community is made up from functional groups that are represented by very few species—extremely low functional redundancy—and therefore highlights potential vulnerability to disturbances.

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Food quality and reef fish diversification

The big disparities in species richness among evolutionary lineages have been fascinating and challenging scientists since Darwin’s time. Although geographical factors have been traditionally thought to promote speciation, the importance of ecological interactions as one of the drivers of diversification has been underscored. For example, is it possible to wonder that food quality might influence patterns of diversification in coral reefsinflatables swimming pool?

new study conducted in Brazil and Australia shows that this is an important aspect to account for when looking at the evolution of coral reef fishes.

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Global change pushing reef fishes towards their energetic limits

_MG_7563 24x16A new study suggests that reef fish species may be hitting a ‘glass ceiling’ as water temperatures raise while reef predators receive substantial energy subsides from sources outside the reefs.

An international team of researchers led by scientists at Macquarie University offers a fresh perspective on threats to the health and biodiversity of reef ecosystems by synthesising energy expenditure data for individual fish with abundance and biomass data collected from reef fish communities all over the world.

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Daily grind shapes coral death

outer_reef_2bThe corals that build spectacular structures, like the Great Barrier Reef, can be killed in many different ways. Over the past few decades, the focus has been on extreme and rare events, such as tropical cyclones, thermal bleaching and outbreaks of the coral-eating crown-of-thorns starfish. However, a new study published in Ecology Letters raises important implications for policymakers to not ignore day-to-day reef death in environmental planning.

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