2015 Expedition: Looking back at our past to understand our future

Aquarium researchers and staff are on expedition to the remote Phoenix Islands Protected Area (PIPA) to study the natural history of the islands, surrounding reefs and connecting open water ecosystems. Research on the 2015 expedition will directly inform the management and maintenance of this world-renowned MPA. Today's post comes from Chip Young. 

Humankind is changing the world’s oceans and the coral reef ecosystems within. Because these changes are happening across the globe at varying rates, how does a concerned citizen develop an understanding of what a healthy coral reef ecosystem “should” look like? We are a group of scientists currently studying the reefs of the Phoenix Islands Protected Area (PIPA), a 407,112 km2 region of islands, atolls, seamounts and open ocean set aside by the Kiribati government to serve as a marine protected area. As scientists, it is relatively easy to assess whether or not coral reefs have been negatively affected by human activities. A more difficult assessment is determining how physical, biological and chemical factors (in the absence of human impacts) intertwine, resulting in a pristine coral reef ecosystem, the type of marine environment people generally think a reef “should” look like.

Phoenix Islands Reefs have higher coral cover and higher fish biomass than many other reefs in the region.
(Photo: Craig Cook). 

  
For the last two weeks, I have been working with a team of scientists from the Woods Hole Oceanographic Institution (WHOI) collecting coral cores from Porites spp.

Chip Young cores from a large Porites coral colony. (Photo: Hanny Rivera)

A historical record of growth can be observed in a “plug” or core retrieved from an individual coral colony. Similar to a tree’s growth rings, corals form bands that often relate to annual growth. The skeletal density of each band and the amount of growth between bands (extension rate) reveal a record of what conditions the coral colony has experienced through its lifetime and how it has responded. Did the marine environment challenge growth or did it promote growth and on what time scales? The physical and chemical environments in which the coral colony has been immersed are represented in the historical growth band record. Looking back in time, and matching bands with historical climatic events (i.e. El Niño, bleaching, rain events/coastal runoff or ocean acidification), reveals how adaptable or resilient the coral colony was to a changing marine environment.  By collecting samples from a variety of reef ecosystems across the PIPA, as well as across the globe, WHOI scientists are constructing a large dataset to help us better understand what factors influence coral growth.

A growing number of coral cores are stored carefully on the right, for later analysis back at Woods Hole.
On the left, Chip sets up water chemistry instruments for reef deployment. (Photo: Sangeeta Mangubhai)

Corals are one of many components making up a reef ecosystem. And no two coral reefs look the same, even at the same island. So, figuring out what a coral reef ecosystem “should” look like takes time and effort. Onboard the Hanse Explorer, our team of biologists and oceanographers are piecing together the parts of the puzzle for this region of the ocean and fine tuning the definition of a healthy reef ecosystem. Researchers are inventorying coral, invertebrate, reef fish, and shark populations, while others are making measurements for water chemistry and collecting biological genetic information. The goal of this collaborative effort in the PIPA is to identify similarities and differences in geographically-similar reef ecosystems, where each ecosystem is far from being directly comparable.

Yashika Nand enjoying a school of jacks as they swim past the reef (Photo: Sangeeta Mangubhai)

Of course similar species live on the reefs within the PIPA, but each reef has its own signature, its own communities of fish and coral. There is not a blueprint for how a healthy coral reef ecosystem “should” look, but there are commonalities in how a healthy reef ecosystem looks. The whole story has yet to be written and the work completed during this research expedition will identify commonalities and differences found in many of the physical, biological, and chemical factors influencing reef health within the PIPA, the greater equatorial Pacific, and across the globe.

Charles (Chip) Young, PhD, is an Oceanographer with NOAA's Coral Reef Ecosystem Division cooperative institute, the Joint Institute for Marine and Atmospheric Research at the University of Hawaii. With NOAA he participates in coral reef ecology research and monitoring projects across the Pacific Ocean, investigating thermal stress and ocean acidification topics. Chip and the Coral Reef Ecosystem Division have been collaborating with Dr. Anne Cohen at Woods Hole Oceanographic Institution since 2010, primarily focused on coral growth and bioerosion rates. For the PIPA 2015 research expedition he'll be participating with the dive team from Woods Hole Oceanographic Institution, studying ocean chemistry, species specific coral growth rates, net reef calcification rates, and variability in benthic community composition.