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Hide and Seek: Unearthing Micronesia’s Lurking Invaders

Photo courtesy of Keoki Stender of

By Anna Simeon, University of Guam Marine Lab

Below the surface of the world’s oceans, invasive algae are causing quite a stir, but thanks to the University of Guam  (UOG) and  Guam Sea Grant, researchers are tackling the threat of invasive algae in Micronesia using modern genetic techniques.

The collaboration initially began with the goal of documenting the unique diversity of marine plants in Micronesia, a remote island group in the western Pacific. Shipping between islands in this region has increased dramatically over the past two decades, raising concerns that invasive algae may be accidentally transported to new areas outside their native range.

Generally, newly introduced species don’t present a problem. But once in a while, an introduced species can become invasive and wreak environmental and economic havoc. One of the most notorious examples is the “killer seaweed,” Caulerpa taxifolia, which has taken over much of the Mediterranean and caused millions of dollars in damage worldwide. With so much at stake, it’s important that we are able to recognize potential invaders before they cause major problems. 

To protect Micronesia from harmful invasions, UOG researchers are making efforts to record and understand the diversity of the region’s marine flora. But identifying algae specimens in the field is not as easy as it seems. Many species appear very similar – sometimes so similar that they cannot be identified without genetic data. To overcome this problem, UOG scientists follow a procedure (known as barcoding) in which a small, select portion of a specimen’s genetic code is sequenced. This short sequence – called a marker – is then compared to sequences from other previously identified specimens and results in a positive identification.

In the process of barcoding and comparing Micronesia’s flora, however, scientists have stumbled upon hidden and previously unknown diversity. In a recent study examining genetic data from one native Micronesian alga (Actinotrichia fragilis), UOG researchers unearthed as many as 6 distinct species lurking within what was once considered a single variety. Although these newly discovered species look similar, their genetic makeup and different geographic ranges indicate otherwise.

Cryptic species like these have a real potential to complicate the war against invasive algae. It is difficult – if not impossible – to predict how introduced algae might affect their new habitat, so monitoring the presence and movement of these understudied species is critical in coastal management. As we continue to unearth the true diversity of our marine environments, genetic tools will to play a key role in helping us manage them.

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