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WHEN ARE ALGAE AT EQUILIBRIUM?

November 17, 2014

WHEN ARE ALGAE AT EQUILIBRIUM?

Anyone who has snorkeled the reefs of Panama’s Bocas Del Toro Archipelago has probably seen large fields of brownish, fan-like algae undulating in the currents where coral once thrived

Anyone who has snorkeled the reefs of Panama’s Bocas Del Toro Archipelago has probably seen large fields of brownish, fan-like algae undulating in the currents where coral once thrived. A massive die-off of algae-eating sea urchins in the 1980s likely aided the proliferation of Lobophora variegata, an indicator of degradation in tropical marine ecosystems.

Across the Atlantic around Spain’s Canary Islands, L. variegata populations took an opposite turn. Overfishing resulted in an increase in sea urchins, which munched the seaweed into scarcity. In that subtropical marine ecosystem the alga is vital to fish and invertebrate reproduction. “Without the alga, the ecosystem deteriorates. It lowers its productivity and its diversity drops,” said Carlos Sangil, who completed his Ph.D. at Universidad de La Laguna, on the Canaries’ largest island, Tenerife.

Sangil recently concluded a yearlong study at STRI. He asked how human activity drove L. variegata to opposite extremes in these two ecosystems. Based at Bocas Del Toro Research Station, Sangil ran field and laboratory experiments to test the alga’s response to increased temperature, nutrients and sedimentation. These anthropogenic factors all influenced algal populations, but he found that herbivory remained the most important driving force.

Sangil’s research to further our understanding of anthropogenic change on marine systems was supported by the Foundation Canarias Dr. Manuel Morales. “We’re talking about great variables of change at a global level,” said Sangil, who was hosted by STRI staff scientist Héctor Guzmán.

Carlos Sangil | Photo by Sean Mattson - STRI

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