Monthly Archives: October 2013

2013 Expedition: Journey to the Southern Line Islands

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Coral reef ecosystems are among the most diverse and productive ecosystems on the planet yet they are suffering significant declines due to human impacts. Because many people depend on reefs and reef fisheries for their livelihoods it is highly important to gain a better understanding of how reef fisheries work. In previous research we were able to document how coral reef ecosystem productivity varied across the Northern Line Islands including islands with and without human habitation. We found that in general reef fishery productivity was lower in systems that are heavily fished. In this upcoming expedition we seek to investigate the complementary question – how does reef ecosystem productivity vary across natural conditions? We will isolate the effects of natural variability by studying a series of uninhabited islands in the Southern Line Islands group. In order to develop effective conservation targets and management strategies we need to know the range of possibility for fisheries across natural gradients in oceanography in the absence of people.

Journey to the Central Pacific
Stretching 2,350 km in a northwest-southeast direction approximately 1,000 miles south of the Hawaiian Islands are a chain of eleven atolls called the Line Islands. The geological history of the Line Islands is complex. It is thought that the islands formed as volcanoes over a series of hot-spots, as opposed to a plate moving over a single hot-spot as is the case with island chains like Hawaii. Today only 11 of the Line Islands are visible, at best a few meters above sea level. The remote nature of these islands, coupled with the biodiversity found here make them ideal areas to study coral reefs.

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One of the longest island chains in the world
The Line Islands are one of the longest island chains in the world and are geographically divided into two subgroups: the Northern and Southern Line Islands. The Northern Line Island chain, where our team visited in 2005 and 2010, is comprised of both inhabited and uninhabited islands, making it the perfect area for exploration and scientific discovery. The ecological research taking place in the Northern Line Islands provides valuable insights into the workings of coral reefs and how these can be altered by human activities. While we depend upon coral reefs to provide food and coastline protection worldwide, we currently lack a clear understanding of how best to use (and not overuse) these resources. The Northern Line Islands serve as a natural experimental system that spans a gradient of human disturbance, from pristine to moderately impacted by people.

The Southern Line Islands are all uninhabited islands within the Republic of Kiribati. These islands protect some of the most pristine and intact coral reefs remaining on the planet, and serve as an invaluable setting to study how coral reefs work in the absence of human disturbance. Interestingly, these islands span a wide range of natural, oceanographic conditions, with the local waters ranging from very nutrient-poor to higher-nutrient upwelling zones. The Southern Line Islands present an unparalleled opportunity to study how oceanographic conditions alter the ecology of a coral reef independently of any effects of humans

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Millennium Atoll

Millenium atoll

Millennium is considered one of the few remaining coral reef ecosystems in the world that is relatively pristine. Inside the lagoon, the dominant corals are branching Acropora, forming plentiful patch and line reefs. These reefs likely provide important nursery habitat for important fisheries species like the blacktip reef shark (Carcharhinus melanopterus) and Napoleon wrasse (Cheilinus undulatus). Both species are heavily exploited throughout the Pacific, the Napoleon wrasse being under consideration for listing under the Endangered Species Act. However, they are abundant at Millennium.

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While the large fishes are some of the most striking underwater and contribute to the large fish biomass on the reef, notably 4 out of every 5 fish on the reef are damselfishes. These relatively small-bodied fish are found amongst the fingers of the abundant Acropora corals. The whitetail dascyllus (Dascyllus aruanus) accounts for 35% of all fish in the lagoon.

Macroalgal cover in the lagoon is low, likely due to the large number of herbivorous (plant-eating) fishes and urchins and competition for space with corals. On the reef crest that is exposed during low tide, crustose coralline algae, a pink calcifying algae that glues the reef together) and turf algae are present.

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The lagoon also hosts a large number of giant clams (Tridacna maxima), with an average of 3.5 clams per square meter in the north central regions. The southern part of the lagoon was reported to have an average of 35 clams per square meter in an 1988 expedition and indeed was found to have one area of 100% clam cover in 2009. However much of this area was littered with dead clam shells, possibly due to human poaching or aerial uplift of the island, leaving the shallow clams too far out of the water to survive.

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Reef development inside Millennium lagoon are due to the dynamic growth and erosion processes, likely punctuated by changes in sea level and disturbance over thousands of years. As the reefs inside the lagoon grow, pillars of calcifying corals and algae have grown together, forming saddles. The result is a reticulate reef formation, which further influences water flow inside the lagoon. Notably, these pillars often grow east to west, which provides animals that eat plankton out of the water column with the greatest access to their food supply.

The outside of the island is surrounded by fringing reef. The windward side, exposed to frequent and large Pacific swells, has reef that rapidly slopes off from shore. The reef on the leeward side begins as a reef terrace that later turns into a steeper reef slope.

On Land and in the Air

Among the animals and plants on land at Millennium Atoll are plants and animals on land are the coconut crab (Birgus latro), named for its ability to crack open coconuts with its claws and Pisonia grandis, a species of flowering tree in the Bougainvillea family. Coconut crabs can grow to be 70 cm in body length (not including legs), have a leg span of 1 m, weigh a few kilograms (with some estimates over 4 kg), and live for decades. Because of their large size and their fabled taste, the coconut crab has been harvested extensively from the inhabited Line Islands. However, remnant populations of crabs thrive on the uninhabited islands with population estimates of hundreds of thousands to millions of crabs.

Pisonia can form dense forests up to 20m in height and provide nesting habitat for a variety of seabirds. Once felled, their wood is relatively weak and rots quickly. While these forests were once abundance throughout the Pacific, in many locations with human habitation they have been replaced with nonnative coconut palms. These non-native coconut palms are also evident on Millennium, left over from a brief fifteen-year attempt by S.R. Maxwell and Company to export copra (dried coconut meat) before the company went into debt.

There are two particularly large populations of nesting seabirds on Millennium. Sooty Terns (Onychoprion fuscata), number about 500,000 individuals largely on the eastern islets of the atoll and Great Frigatebirds (Fregata minor) number approximately 10,000.

 

The Southern Line Islands

In addition to Millennium Atoll, there are four other Southern Line Islands: Malden, Starbuck, Vostok, and Flint. All of these islands are part of the Republic of Kiribati and are currently uninhabited with minimal past or present human impact.

Malden
Malden is approximately 11 square miles with large interior salty lakes. It has evidence of previous habitation by Polynesians before European discovery. Guano deposits were mined in the early 20th century and depleted by 1920. The British used Malden to test nuclear weapons in the late 1950’s. It became a wildlife sanctuary and reserve in 1975 before the formation of the Republic of Kiribati in 1979.

Starbuck
The island is named after Valentine Starbuck, who first spotted the island in 1823 from his British whaling ship. It was annexed by Britain in 1866 and mining for guano began shortly thereafter, continuing for the next 50 years. The island is barren and uninhabited, but home to breeding populations of millions of sooty terns, among other seabirds. Similar to Malden, Starbuck has a continuous land edge with inland salty lakes.

Vostok
Vostok is a 24-hectacre island that occupies most of the reef platform upon which it rests. Vostok and Flint are the most southern of the Line Islands and receive less rainfall than the other islands (approximately 500 mm per year). These average rainfall patterns are a result of the islands’ location south of the intertropical convergence zone, which remains north of the equator throughout the year in the region of the Line Islands. Vostok is only one square mile with no anchorage in the lagoon. It was named in 1820 by the Russian Antaractic explorer Bellingshausen who named the island after his ship. The island was never exploited for guano and attempts at establishing a plantation there in 1922 failed. As a result, Vostok’s indigenous flora is the least disturbed of the Line Islands.

Flint
Flint is the southernmost island of the Southern Line Islands. It has an area of one square mile with several brackish lagoons. Like Vostok, it receives much less rainfall than the other Line Islands (500 mm per year). The island was developed for guano working and copra plantations in the late 1800’s. While most of the native flora was replaced with coconut palms, the coconut crab population is in the tens of thousands.

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From the Field: How Long Do Corals Need to Recover?

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  • Discovering clues about an ecosystem’s recovery from a catastrophic event – check.
  • Developing new international partnerships for Scripps Institution of Oceanography, UC San Diego – check.
  • Learning to love eating fresh tuna for nearly every meal – check!

These were three of the things that we accomplished this summer during our one-month stint on a tiny island in the Maldives.

jharris_healthy reefAs marine conservation biologists, we are concerned with the worldwide degradation of coral reefs due to human activities such as fishing, pollution, and the effects of global climate change. Coral reefs are complex ecosystems, so we and the other members of marine ecologist Jennifer Smith’s research group studies the ecology of remote reefs to get an idea of how they are supposed to work without human interference. Once we understand this, we can set realistic and effective conservation goals. It is exciting work, and it means that we frequently travel to very tiny islands that are very far away from our comfortable home base at Scripps.

jharris_korralian lab bungalowOur most recent tiny island trip was to the brand new Korallion Lab, a marine science research station on in Lhaviyani Atoll in the Maldives. Scripps is one of the lab’s founding member institutions, along with Woods Hole Oceanographic Institution, University of Newcastle in the United Kingdom, and ReefCheck Italia.

The Maldives are an interesting place to work because they were hit hard by a massive coral bleaching event in 1998. Corals are sensitive to temperature, so a temperature increase of a few degrees causes them to become stressed, expel the tiny algae that live in their tissues (losing their characteristic color, hence the term ‘bleaching’), and eventually die. Bleaching events happen worldwide with unfortunate frequency, but the 1998 event in the Indian Ocean was the most severe ever recorded. Levi Lewis, a fellow Scripps graduate student, and I were on a mission to discover if there are any lingering effects of that bleaching event on the Maldives’ coral, fish, and other marine life.

jharris_levi lewisUnfortunately, there were few marine scientists working in the Maldives prior to 1998, so we lack comprehensive before-after comparisons to quantify what the bleaching did to Maldivian reefs. But studying Maldivian reefs today can provide clues about what these waters used to look like and even offer hints of what the future might hold. For example, consider this piece of evidence: we saw formerly thriving reefscapes composed of huge, centuries-old corals that were still jharris_in the labstructurally intact but completely dead and overgrown with algae. If these huge corals had been dead for a long time, they would have been eroded into smaller pieces. If there were only one or two dead corals, it might be a matter of disease or coral-eating predators. However, swimming around an area the size of several football fields, we would see hundreds of these huge ghost coral colonies, suggesting that a fairly recent and dramatic event killed all the coral at the same time.

jharris_dead reefWe routinely observed two types of evidence that give us hope for the future of Maldivian reefs. Many of these ghost reefscapes were speckled with small colonies of live corals that appeared to be only a few years old. Such a scene hints that some coral species are beginning to re-colonize the area. And in sharp contrast to the dead reefs, we encountered several thriving reefs filled with diverse, living coral and schools of colorful fish. Because these thriving reefs were composed of many large, old coral colonies, we think that the 1998 bleaching had little impact on select coral communities in the region.

Why have some areas become ghost reefs that were apparently decimated by the 1998 bleaching event, while other areas appear to have been resilient to the bleaching and persist as thriving, diverse underwater landscapes?

The answer is complicated.

jharris_coral recruitOne of tools we use to assess reef health is the Coral Health Index (CHI). Developed by a multidisciplinary group of reef scientists, including Scripps marine ecologist Stuart Sandin, CHI streamlines an array of coral reef variables that we could measure into just three simple metrics: fish biomass, abundance of calcifying organisms on the seafloor, and population of pathogenic bacteria in the water. High fish biomass tells us that the food web is intact: generally, if there are a lot of big fish, then the rest of the food web is probably there, too. An abundance of calcifying organisms tells us that the reef is actively growing over time. Finally, low levels of pathogenic bacteria tell us that the water is clean and minimally impacted by human activities.

Jharris_coral surveySo, there we were, measuring CHI all around Lhaviyani Atoll, a sparsely populated group of islands about 35 kilometers (22 miles) in diameter. We hoped to find a pattern that could tell us why some reefs survived the 1998 bleaching unscathed, some were beginning to recover, and still others were decimated with no signs of recovery. What we learned was puzzling: there was no obvious pattern distinguishing the healthy from the unhealthy reefs.

Now back at Scripps, Levi and I continue to process samples and analyze data, trying to make sense of what we learned. The Maldivian government is acutely interested in protecting the country’s reefs, so our results will help legislators make decisions about how to take action in the future. More broadly, the scientific community has much to learn about why reefs respond differently to bleaching events and other disturbances.

jharris_sea starOh, and about all that fresh tuna that we ate during our research trip: tuna fishing is the second largest economic sector in the Maldives (after tourism). Since the country is comprised entirely of tiny limestone islands with no soil, agriculture is virtually nonexistent, leaving fish as the only source of protein. We ate tuna for breakfast, lunch, and dinner. Sometimes wrapped up in Bangladeshi-style roti bread (at breakfast), sometimes as a tuna salad sandwich (lunch), and sometimes fried into delicious nuggets (dinner). Though we may have filled our lifetime cap on mercury, all that tuna kept us happy and well-fueled for the tiring work of trying to figure out just what will happen to the Maldives’ beautiful coral reefs.

Introducing… Abby Cannon, PhD Student

Abby Cannon has been a part of the Smith Lab family since 2009.  She is a UCSD alum, graduating with a B.S. in Environmental Studies: Ecology, Behavior and Evolution in 2009 and started off as a volunteer assisting PhD student Levi Lewis with his SCUBA research-identifying algae and processing data.

Starting Fall 2013, she is now one of the newest PhD students in the Smith Lab.  She gives us a brief glimpse into how she’s preparing for graduate school and on her new exciting research studying queen conchs (Lobatus gigas).

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An Introduction

By Abby Cannon

babybaulaAfter studying sea turtles in Costa Rica, traveling through Latin America, and helping Levi Lewis with his research on Maui I’m once again back in the Smith Lab. This time I’m a PhD student instead of a volunteer. I’m very grateful to all of the members of the Smith Lab, especially Levi, for mentoring me as a scientist and helping me to get my foot in the door.

 

Guayaquil localsOther than volunteering in the Smith Lab I have prepared myself for graduate school by getting my AAUS Scientific Diving certification at the University of Washington, interning at Griffith University in Australia, and traveling extensively through Africa, and Latin America. My adventures abroad helped me to better understand the environmental attitudes of different cultures and the challenges of reconciling environmental protection with economic and social development.

 

conchsforsaleIn keeping with my interest in the intersection of environment and culture I hope to conduct my graduate research on queen conchs (Lobatus gigas). These giant sea snails have long been a staple of the Caribbean diet and a symbol of the region, but unfortunately their population is declining due to overharvesting. While studying at Scripps I aim to investigate the effects that conch overharvesting has on Caribbean marine ecosystems and work to come up with culturally and economically acceptable solutions to this problem.

 

It’s Not a Sprint….

It’s a marathon.  Rather, it’s a marathon-length obstacle course.  Rather, it’s a marathon length obstacle course throughout which one must sprint (and jump, climb, dive, bleed, cry, swim, crawl…you get the idea).

They say I’m lucky, and I am.  But perspective means everything.

This has been quite a busy 2013:

Levi Lewis_Map of 2013 Research Projects

February:  Maui Research
March: Dissertation Qualifying Exam
May: Maui Research
June: Maldives Research
July: Northwestern Hawaiian Islands Research
August:  Kahoolawe Research
September:  Maui Research

Basically, a lot of this:

Levi diving

 

 

 

 

 

 

 

Yep, it’s September now, and I’m finally seeing the light at the end of this year’s odyssey.

I haven’t had time to keep up with blogging, or emails, or contacting friends/family, sleeping or breathing regularly.  But this time of blissful madness is coming to an end and I, at last, have time to reflect.

I have a ton of adventures to report on, going back over a year ago.  These will come piecemeal, as time opens up.  I can’t wait to reflect, relive, and enjoy the experiences that have passed.  Some say one shouldn’t live in the past; rather, to live in the present.   Sometimes, however, one was simply working too hard to enjoy the present, so reflecting on the previous presents via images, videos and stories is quite attractive at the moment…

I did mention that I’m seeing the light, but I still reside deep within the tunnel.  So for now, I’ll be mostly dealing with the the present, which remains highly algified (a good thing).

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To find out more about Levi’s research check out his blog!

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