Our summer fieldwork season has begun! It’s going to be a very productive and exciting summer filled with new connections, exciting new data, and much more! I’m really excited to have a great and diverse team of undergraduates joining us in the field this summer! First, I am excited to have an incoming freshman undergraduate student from the Native Hawaiian Science & Engineering Mentorship Program Freshman Bridge program, Kelsi Julian-Araki. Kelsi expressed an interest in marine science and will be conducting a project of her own, while assisting with other projects and gaining field and lab experience. Also joining our team is Kelsey Cushway, all the way from Michigan she is a geology major who is (or will be) interested in our submarine groundwater discharge work. Kelsey is joining us through a Research Experience for Undergraduates grant. I also have three recent graduates of our senior level Hawaiian phycology course joining us, Katherine Cockerille, Dominique Elento, and Kevin Ravago. As graduates of botany 480 my senior level phycology students are trained to identify all the algae we might find on the reef. As a geology REU Kelsey will be a great help for the hydrogeology field methods. And, as a local student Kelsi’s familiarity with the island will be a great help in the field, while her enthusiasm for marine science early on in her education will be very welcome on our team!

Beautiful days and extreme low tides at Wailupe.

Gracilaria salicornia collections.

A huge thank you to all of my volunteers thus far, from the Limu Lab Scott Van De Verg and alumni Megan Onuma! From my family, thank you to my mom and James Morgan! I have really enjoyed getting out in the field with all of you.

This past weekend I volunteered with Friends of Kahana at the Huilua Fishpond, one of my field sites. An interesting connection between my field sites, those with submarine groundwater discharge, and ancient Hawaiian fishpond sites. Many sites with submarine groundwater springs are also sites that were chosen by ancestral Hawaiians as sites for loko iʻa, or fishponds. This is in part because many fish species travel between these estuarine, where fresh water and salt water are mixing, during their lifespan. The estuary is a natural nursery for many reef fishes.

The end of the semester is always a busy time with the culmination of classes and grading, so it was great to get out and do some physical work to give back to the community at one of my field sites. The caretakers of Huilua fishpond were wonderful people to meet who have a great knowledge of Kahana, having lived there their whole lives and their family for generations before them. In their lifetime Huilua has become inundated with invasive mangroves (Rhizophora mangle is the most common mangrove species in Hawaiʻi, though several exist) and guinea grass (Panicum maximum).

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Guinea grass (Panicum maximum) fills the northern end of the fishpond. Here the lovely ladies of Kahana are clearing with weed whip while I dig out the roots with an o`o bar. Kahana bay and valley can be seen in the background.

The mangroves have grown over and most likely altered the natural spring that feeds into the fishpond, while the cane grass has blocked one of the auwai, or gates that allow fish and salt water into the loko iʻa from the ocean. Kahiau, the caretaker of the site, explained to me that the plan is to remove the fountain grass and dredge the sediment that has accumulated inside the pond, and to remove the mangrove by chainsaw. I am certainly interested to get a baseline benthic analysis of the reef community outside the loko iʻa and to monitor for any changes with the restoration of the spring and the loko iʻa to their historical conditions.

There are so many duties to stay on top of as a scientist, research, data processing, writing, publishing, presenting your research. However, connecting with the community is one of the most important and often forgotten responsibilities we have as scientists today. Without a connection to the community your research may never be enacted or understood by the people who are effected by it. What’s more is the people who live and work in these environments are the true experts of these ecosystems, and are often great resources to help your research become much more informed and useful than it would without their input. As someone who is trying to understand an ecosystem in the short timespan of a PhD thesis, in just 3 or 4 years, people who have spent their lifetimes and have knowledge that has been passed down through generations are an amazing resource when it comes to the cycles, changes, and natural phenomena of a place.

Mangroves can be seen in the back corner of the loko iʻa, most likely covering the site of part of the submarine groundwater discharge spring.

Another beautiful day of field work on the south shore of Oʻahu. Currently, I am doing percent cover analyses of various sites with Submarine Groundwater Discharge (SGD) influence across Oʻahu. Each of these seeps has different characteristics, including pH, salinity, temperature, natural nutrient concentrations, and amount of pollution from anthropogenic nutrient loading (septic tanks, leaking sewer lines, fertilizers, piggeries, chicken farms, etc.). My goal is to characterize the relationship between the seep characteristics and the coastal marine ecosystem. Some of these seeps have been connected to harmful algal blooms due to very high nutrient loading from agriculture and sewage pollution. However, SGD is a naturally occurring and integral part of the connectivity of watersheds and coastal ecosystems, carrying naturally occuring nutrients from the ridge of the mountains to the reefs. I want to learn more about how these SGD seeps influence coral reef ecosystem dynamics through my PhD thesis.

This past Thursday I went to the field to scout field sites on the Northeast side of Oʻahu. Here, many sites with groundwater inputs were traditionally used for aquaculture in Hawaiian fishponds. These embayments already provided a good habitat for juvenile fish; the Hawaiians, recognizing the natural nurseries of valued food species, imposed rock walls around these areas in order to cultivate these species in their natural environment. These areas provided a sheltered, steady supply of fish while ocean fishing is not always as reliable. The pond also provides a sheltered natural environment for limu to grow, thus, these herbivorous fish species do not need to be fed as their natural food source is cultivated by the pond system. The six kinds of fishponds found in Hawaii are a unique and advanced type of aquaculture found no where else in the world.

A key feature of these ponds is the mākāhā, the sluice gates that allow smaller fish to leave the pond, but prevent larger fish from escaping. Combined with the brakish water this creates an environment for species that travel between fresh and salt water during their life cycle, such as ‘ama’ama (striped mullet, Mugil cephalus), awa (Milkfish, Chanos chanos), pualu (surgeonfish), palani (Eye-stripe surgeonfish, Acanthurus dussumieri), āholehole (Hawaiian flagtail, Kuhlia xenura), moi (Sixfinger Threadfin, Polydactylus sexfilis), kākū (great barracuda, Sphyraena barracuda), and papio (young trevally).

Heʻeia fishpond, in Kāneʻohe, Oʻahu.

Heʻeia fishpond was built 600-800 years ago, and is one of the largest, if not the largest, in the Hawaiian islands. Heʻeia comprises 88 acres of water. Heʻeia fishpond has been restored and maintained by Paepae o Heʻeia, a nonprofit organization founded in 2001, this organization is dedicated to the fishpond and works in partnership with Kamehameha schools, the land owners of Heʻeia. Most of this information was gleaned from their beautiful Pae Pae o Heʻeia website, where you can find lots more information about Heʻeia.

Huilua fishpond, in Kahana, Oʻahu

Huilua is a smaller fishpond, comprising 7 acres of Kahana bay. Kahana is part of the Hawaiian Division of state parks, and is maintained and restored by a group of local residents called the Friends of Kahana. It is said that two moʻo, large lizard water spirits, are the protectors of Kahana from environmental and human treats (such as fish theft).

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My first visit to an atoll did not disappoint. Coral atolls are formed when an extinct seamount or island erodes or subsides beneath sea level. A lagoon forms over the caldera and a coral rim remains above or just below sea level around the edge of the atoll. In the case of Tikehau, the reef around the lagoon is almost continuous, with just one pass, Tuheiava Pass, connecting the open ocean to the inner lagoon on the western side of the atoll. Tikehau is located 340 kilometers northeast of Tahiti, the capital of French Polynesia. The area of the lagoon is 461 square kilometers, while the islands that form the rim consist of two major islands and many small islets. 500 people live on the atoll of Tikehau, with most living in the main village, while 8 families live on the remote islets around the lagoon.

The main village of Tikehau is called Tuherahera, and it takes about 20 minutes to bike from one end of town (and the island) to the other. We stayed on the South end of Tuherahera, at Pension Justine.

Tikehau catches enough fish to feed themselves, tourists, and to export their catch to the capital of Papieete on the island of Tahiti, and other surrounding islands.

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Most of the fish are caught in this fish trap at Tueheiava pass. We were able to freedive through the pass and experience the current that these fish feel on the incoming tide. It is STRONG! The trap guides the fish into successively smaller chambers with smaller exits and they are unable to escape. Every fish you can imagine was in these traps, including huge moray eels. A large tiger shark even came up to check us out from behind while we were surveying the traps.

The abandoned pearl farm in the center of the lagoon is a known manta ray cleaning station. The Mantas visit this spot in the early morning to be cleaned by the wrasses at the coral head cleaning stations. It was amazing to see the manta rays during the day, as I have mostly dove with them at night in Hawaii.

The amount of fish at the pass was really remarkable. Schools of fish swam at different depths, so there were layers upon layers of schools with all different colors. Here, my friend Morri Sides swims down into a school of Jacks. Above, you will see a school of barracuda that circled us as we floated through the pass. White tip sharks were shy but flitted in and out of the scene at the deeper edge of the pass, while black tip reef sharks hung out near the surface at the edge of the barrier reef.

So, you may be wondering, what about the algae?! There was not much macroalgae present at the pass, as you may expect with such large herbivore numbers. What was interesting is inside the coral lagoon the sand bottom extends out into the deeper waters of the lagoon. When I swam down just off the edge of the beach within the lagoon, I began to feel a layer of warm water. It seems to me that the marshes that are common across the atoll are discharging water at depth within the lagoon, and I was able to feel the heat signature of this beneath the cooler seawater. All along the rim of the atoll where this warm water discharged was a meadow of seagrass. It seems the seagrass is taking advantage of the nutrients from the marsh ecosystem as it discharges within the lagoon.

2016 is coming to a great end. I’m vacationing with my family in French Polynesia for the holidays, we spent one week in Moorea and one in Tikehau. Moorea is the neighboring island to Tahiti, the island that houses the capital of French Polynesia. Moorea is a high island with a barrier reef and a beautiful lagoon that is home to many black tip reef sharks, lemon sharks, grey reef sharks, eagle rays, and pink whip rays. Our time diving in Moorea was absolutely amazing. The sandy lagoon is filled with sections of mounding coral heads and branching Acropora beds. Within the Acropora beds filamentous algae provides habitat for small seahorses.

Can you see the seahorses?

The reefs are also home to the poisonous and elusive stonefish.

Can you see the stonefish? He’s looking right at you!

We spent two days on Captain Taina’s Glassbottom boat. Captain Taina is an amazing captain, her family has kept the land surrounding this are of the lagoon and the motus (islets) within it for generations. During her time captaining her glassbottom boat tour the community has worked to create a protected area for marine life in the area. The motus and surrounding mangroves are an important nursery area for many species, supplying juveniles for much of the lagoon of Moorea. Young blacktip sharks, fish, and other species survive within the safety of the mangrove roots. Here in Moorea mangroves are native and an integral part of the island and lagoon ecosystem. Captain Taina even showed us a large green sea turtle that she rescued from a market, where she was to be sold for food, and released in front of her home here on Moorea. The turtle happily resides within the marine preserve that fronts Taina’s property. To meet the rays and blacktip sharks in Moorea, Captain Taina is the best! I highly recommend her tour!

Diving with black tip reef sharks and rays on Captain Taina’s glassbottom boat tour. Photo by Elizabeth Sides.

It’s our last day here on Tikehau, so I’ve got to get in the water. I will have to update about the limu of Moorea and the rest of my trip on Tikehau later. Happy holidays!

Manuia!

Veronica

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