Researchers discover four new species of marine algae

University of Guam researchers have discovered four new species of Crustose Calcifying Red Algae (CCRA), a group of marine algae that deposit limestone like stony corals — including one that has been named after the UOG Marine Laboratory in honor of its 50th anniversary.  

The study, which was funded by the university’s National Science Foundation EPSCoR grant, was published in November by the peer-reviewed journal PLOS ONE.  

CCRA are a dominant and diverse group of organisms on Guam’s reefs that are difficult to identify and have sometimes been mistaken for coral. They serve several important ecological functions on reefs such as building and cementing reefs together or serving as the preferred settlement substrates for coral larvae which then further develop into adult colonies. 

Since 2017, more than 500 CCRA specimens have been collected from numerous sites around the island. A number of those specimens represented six species of red algae belonging to the genus Ramicrusta. Four of these species are new species to science and Guam now has the highest documented diversity of Ramicrusta species in the world. 

“In other parts of the world such as the Caribbean and Taiwan, certain Ramicrusta species are known to overgrow and outcompete other reef organisms on disturbed reefs,” said lead author Matthew Mills, a UOG alum and Marine Laboratory research associate. “Given their ecological importance, we decided to investigate them into detail.” 

Naming the new species  

The four new CCRA species were named after the CHamoru names of their type locality, which are the collection sites that were used to describe the new species. 

Two of the new species were found in Pago Bay. Ramicrusta labtasiensis was collected from the seawater intake channel behind the UOG Marine Laboratory. 

“We wanted to highlight the Marine Laboratory’s 50th anniversary, which happened last year,” said Tom Schils, a UOG Professor of Marine Biology and the co-author of this study. “Most of the anniversary celebration events were canceled because of the pandemic, so we thought it was fitting to name this new species after the Marine Laboratory for all the important biodiversity work that has been conducted at the unit since its founding in 1970.”  

Ramicrusta taogamensis was named after Taogam Point, which delineates the northern boundary of Pago Bay.  

The other two new CCRA species were found in Talo’fo’fo. Ramicrusta adjoulanensis was named after Adjoulan Point, which is located at the mouth of Talo’fo’fo Bay. Ramicrusta asanitensis was named after Asanite Cove, also known as First Beach.  

“This species is a common alga at this popular beach in Ipan,” said Schils. “As a seaweed biologist, I had always been bothered that I could not identify this alga from a beach that we visited often with the family. Now, we have finally resolved that this is a new species of a genus that had previously not been reported for Micronesia.” 

Mills and Schils are currently working on a larger diversity assessment of CCRA from Guam.  

“Before we started our studies, the only in-depth survey of CCRA on Guam was done in 1975,” said Mills.  

Schils added, “CCRA play an important role in the community changes that we are witnessing on Guam’s reefs. Resolving the diversity of this group is a first step in understanding their contribution to reef health.” 

New Algae Species Photo 3
Example of a common and abundant calcareous red alga from Guam’s waters.
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