The Research Problem
When an ‘opihi (a Hawaiian limpet) on the shoreline of O‘ahu spews tiny larvae out into the wide ocean, will the larvae come back to the same rock, the same island, or the same region?  This information is crucial to conservation, because wildlife managers need to know how far the larvae go. Many reef creatures have an oceanic phase (larvae), which lasts 20-60 days, followed by settlement onto a reef where they remain through juvenile and adults stages.  Therefore, connectivity between reefs is accomplished almost exclusively by larvae.

Why does connectivity matter?  If Yellow Tangs around an island are depleted by overfishing, will that island get Yellow Tang larvae arriving from other islands, or does it have to recover by itself?  If the island has to recover in isolation, it will take much longer and may not happen at all. Another big connectivity question asks if the pristine reefs in the Northwestern Hawaiian Islands send larvae to replenish the depleted reefs of the Main Hawaiian Islands?  And lastly, where did all this Hawaiian biodiversity come from?  Every living thing in Hawai‘i had ancestors that came from somewhere else.

Methods

In the reef connectivity project, we use advanced genetic technology to obtain DNA fingerprints for dozens of species that occur across the Hawaiian Archipelago.  With grants from the National Science Foundation, we survey these same creatures across the far Pacific, to determine where our Hawaiian ohana (family) of sea creatures came from.

Findings
Through our genetic connectivity research thus far, we have been able to draw some amazing conclusions. The Hawaiian limpet (‘opihi) has larvae that may not come back to the same rock that their parents live on, but will probably come back to the same island. Researcher Chris Bird has shown that if ‘opihi are depleted on Kaua‘i, their recovery may be slow, because Kaua‘i shorelines only get ‘opihi larvae from Kauai parents.  This differs from the Yellow Tang larvae that can disperse a little further than the ‘opihi. The Yellow Tang that hatch on Kure Atoll may settle down at the adjacent, Midway Atoll.  Researcher Jeff Eble has shown that Yellow Tang are divided into at least seven isolated populations in Hawai‘i.  This is important because the Yellow Tangs are heavily harvested for the aquarium trade.  If one population is overharvested, it will not get much help from other populations.

The protected Northwestern Hawaiian Islands does not send many larvae to the reefs of the inhabited Main Hawaiian Islands.  Graduate students Michelle Gaither and Matthew Iacchei have shown that the prevailing currents push larvae in the opposite direction, from Main Hawaiian Islands to the Northwestern Hawaiian Islands, also known as the Papahānaumokuākea Marine National Monument.  Having one of the largest marine reserves in the world, and the largest in the United States does not alleviate the need for responsible management of the reefs in the Main Hawaiian Islands. Researchers at the Hawai‘i Institute of Marine Biology look at the genetic connectivity and the direction of larvae settlement in order to understand where our species come from and how to better protect them. Some of our Hawaiian sea creatures came from the direction of Polynesia, to the south, and some from the direction of Japan, to the west.  Graduate student Derek Skillings demonstrated a connection between sea cucumbers in Hawai‘i and those in the Line Islands, which straddle the Equator between Hawai‘i and Polynesia.  Researcher Matt Craig showed that two Hawaiian Butterflyfishes came from the West Pacific.  Finally, Chris Bird showed that our humble ‘opihi had ancestors in Japan.

Importance
In all these cases, the ancestors of our Hawaiian fauna colonized through the Northwestern Hawaiian Islands, which we now know includes an important biodiversity gateway into Hawai‘i. Our research continues to explore these ideas by looking at the connectivity of deep “foundation reefs”, identifying new species of coral, and providing the best scientific foundations for reef conservation.

Selected ToBo Lab References on connectivity

Kimberly Andrews, Hawaiian spinner dolphin (Stenella longirostris), Hawaiian grouper (Epinephelus quernus), crown-of-thorns sea star (Acanthaster planci)

Molecular Ecology, Journal of Marine Biology

Christopher Bird, sympatric limpets (Cellanaspp.), sea cucumber (Holothuria atra.), crown-of-thorns sea star (Acanthaster planci)Molecular Ecology, Journal of Marine Biology

Gregory Concepcion, octocoral (Carijoa), coral (Montipora & Porites lobata) PLoS ONE, Marine Ecology Progress Series, Molecular Ecology

Matthew Craig, Hawaiian butterflyfishes (Chaetodon spp.), blueline surgeonfish (Acanthurus nigroris), brown surgeonfish (Acanthurus nigrofuscus), grouper

(Cephalopholus argus) Journal of Marine Biology, BMC Evolutionary, Journal of Biogeography, Coral Reefs

Joseph DiBattista, Pacific blueline surgeonfish Acanthurus nigroris, butterflyfishes (Chaetodon spp.), round herring (Etrumeus spp) Journal of Marine Biology, Conservation Genetic Resources, Pacific Science

Jeff Eble, Hawaiian butterflyfishes (Chaetodon spp.), brown surgeonfish (Acanthurus nigrofuscus), yellow tang (Zebrasoma flavescens). Journal of Biogeography, Journal of Marine Biology, Marine Ecology Progress Series

Zac Forsman, coral (Montipora) PLoS ONE

Michelle Gaither, bluestriped snapper (Lutjanus kasmira), blacktail snapper (Lutjanus kasmira), grouper (Cephalopholus argus) BMC Evolutionary Biology, Molecular Ecology, Journal of Biogeography

Roxanne Haverkort, coral (Montipora) PLoS ONE

J.S. Reece, moray eels (Muraenidae) Marine Ecology Progress Series, Journal of Heredity

Malia Rivera, Hawaiian grouper (Epinephelus quernus) Journal of Marine Biology

Luiz Rocha, brown surgeonfish (Acanthurus nigrofuscus), blueline surgeonfish (Acanthurus nigroris), grouper (Cephalopholus argus) Journal of Marine Biology, BMC Evolutionary Biology, Coral Reefs, Molecular Ecology

Jennifer Schultz, Hawaiian monk seal (Monachus schauinslandi), flame angelfish (Centropyge loriculus) Marine Biology, Conservation Biology, Journal of Heredity

Derek Skillings, sea cucumber (Holothuria atra.) Journal of Marine Biology

Molly Timmers, crown-of-thorns sea star (Acanthaster planci) Journal of Marine Biology

Daniel Wagner, black corals (Cnidaria: Antipatharia) Proceedings of the Royal Society, Pacific Science

Christie Wilcox, Pacific blueline surgeonfish (Acanthurus nigroris) Journal of Marine Biology, Pacific Science

Related Documents

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• Clade D Symbiodinium in Scleractian Corals
• Selected ToBo Lab References on Connectivity