September 2017

Special Issue on Sedimentary Processes Building a Tropical Delta Yesterday, Today, and Tomorrow: The Mekong System



VOL.30, NO.3, SEPTEMBER 2017

Special Issue on

Sedimentary Processes Building a

Tropical Delta Yesterday, Today, and Tomorrow:

The Mekong System


VOL.30, NO.3, SEPTEMBER 2017


VOL.30, NO.3, SEPTEMBER 2017





VOL. 30, NO. 3, SEPTEMBER 2017



FROM THE GUEST EDITORS. Introduction to the Special Issue on

Sedimentary Processes Building a Tropical Delta Yesterday, Today, and

Tomorrow: The Mekong System

By C.A. Nittrouer, J.C. Mullarney, M.A. Allison, and A.S. Ogston


How Tidal Processes Impact the Transfer of Sediment from Source to Sink:

Mekong River Collaborative Studies

By A.S. Ogston, M.A. Allison, R.L. McLachlan, D.J. Nowacki, and J.D. Stephens


A Question of Scale: How Turbulence Around Aerial Roots Shapes the

Seabed Morphology in Mangrove Forests of the Mekong Delta

By J.C. Mullarney, S.M. Henderson, B.K. Norris, K.R. Bryan, A.T. Fricke,

D.R. Sandwell, and D.P. Culling


Buried Alive or Washed Away: The Challenging Life of Mangroves in

the Mekong Delta

By S. Fagherazzi, K.R. Bryan, and W. Nardin


The Mekong Continental Shelf: The Primary Sink for Deltaic Sediment

Particles and Their Passengers

By C.A. Nittrouer, D.J. DeMaster, E.F. Eidam, T.T. Nguyen, J.P. Liu, A.S. Ogston,

and P.V. Phung


Challenges of Observational Oceanography in the Modern Coastal Ocean

By C.A. Nittrouer


Stratigraphic Formation of the Mekong River Delta and Its Recent

Shoreline Changes

By J.P. Liu, D.J. DeMaster, T.T. Nguyen, Y. Saito, V.L. Nguyen, T.K.O. Ta, and X. Li


Modeling the Process Response of Coastal and Deltaic Systems to Human

and Global Changes: Focus on the Mekong System

By E. Meselhe, D. Roelvink, C. Wackerman, F. Xing, and V.Q. Thanh


Sedimentation and Survival of the Mekong Delta: A Case Study of Decreased

Sediment Supply and Accelerating Rates of Relative Sea Level Rise

By M.A. Allison, C.A. Nittrouer, A.S. Ogston, J.C. Mullarney, and T.T. Nguyen


Sedimentary Processes Building a Tropical Delta Yesterday,

Today, and Tomorrow: The Mekong System

Oceanography | September 2017


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Production of this issue of Oceanography was

supported by the Office of Naval Research

through grant N00014-17-1-2888 to the

University of Washington, Seattle.


• CHARLES NITTROUER, University of


• JULIA MULLARNEY, University of Waikato

• MEAD ALLISON, Tulane University

• ANDREA OGSTON, University of



Landsat image of the Mekong Delta and adjacent

ocean on September 18, 2014, during period of intense

fieldwork described in the special issue section. Shown

are the turbid distributary channels, complex mangrove

shorelines, and surface plumes extending into the East

Sea. Image was processed by MDA Information Systems,

and is oriented so north is up on the page.



Internal Waves Along the Malvinas Current: Evidence of Transcritical

Generation in Satellite Imagery

By J.M. Magalhães and J.C.B. da Silva


03 QUARTERDECK. The Garden of Science

By E.S. Kappel

05 FROM THE PRESIDENT. Planning the Future of Ocean Sciences

By A.C. Mix

06 RIPPLE MARKS. The Jumbo Carbon Footprint of a Surf-and-Turf Dinner

By C.L. Dybas

120 HANDS-ON OCEANOGRAPHY. Assessing Cross-Shore and Alongshore

Variation in Beach Morphology Due to Wave Climate: Storms to Decades

By S.L. Gallop, M.D. Harley, R.W. Brander, J.A. Simmons, K.D. Splinter,

and I.L. Turner

126 THE OCEANOGRAPHY CLASSROOM. Inspiration: The Source and the Drive

By S. Boxall

128 BOOK REVIEW: The Oceanographer’s Companion: Essential Nautical Skills

for Seagoing Scientists and Engineers by G.A. Maul

Reviewed by C.L. Van Dover

129 CAREER PROFILES. Sara Bender, Program Officer, Gordon and Betty Moore

Foundation • Danny Richter, Legislative Director and Director of Research,

Citizens’ Climate Lobby

132 AWARDS. The 2017 Walter Munk Award: Andone C. Lavery



Oceanography | Vol.30, No.3


The Garden of Science

It’s summertime, and I’ve been thinking a lot about gardens. Nearly

30 years ago, when my husband and I bought our home, the small

back yard was a strange mixture of a grass lawn, a day lily patch that

bloomed for one glorious week per year, azaleas, oak trees—some

healthy, some nearly dead—and crumbling terraces for smaller plants.

During the next phase of life, the dead trees came down, the lily patch

was replaced by a swing set, and the highest spot on the lawn became

my son’s pitching mound. Today, there’s no lawn at all, trees that were

planted when my children were young stretch far into the sky, and a

winding path runs through what is now a shade garden. Nothing stays

the same for very long. The acidic contributions of three large dogs cre-

ate additional challenges to keeping the garden lush. If the past is any

indication of the future, the new young raspberry bush I just planted in

the male dog’s favorite spot doesn’t have a chance. But, I remain hope-

ful, and will do my best to see that it survives whatever may come.

Reading the newspaper each morning can make it difficult to be

optimistic about the current direction of US science. Day after day, we

read about possible significant budget cuts to science agencies, while

at the same time learning about the enormous chunk of Antarctica’s

Larsen C ice shelf that just broke free, the mass bleaching of corals,

and the many wildfires that are burning vast acreage in the western

United States and elsewhere around the globe. Confronted with these

disheartening developments, it may be helpful to think about the

US scientific enterprise as a garden that thrives with the proper amounts

of sun and rain, and at other times suffers from drought or neglect.

The scientific landscape has changed many times over the years with

shifting personnel, policies, and priorities. It’s not new for Congress to

cut science budgets, nor for an Administration to challenge scientific

research. It’s not new for politically appointed agency heads to recon-

sider science-based regulations. It’s not new for an Administration

to weigh (or ignore) science based on economic or political inter-

ests. In times like these, it is more import-

ant than ever that we not neglect the scien-

tific garden, that we continue to nurture

it as best as possible, so that when the

time is right, it will come into full

bloom once again.

Ellen S. Kappel, Editor

December 2017

Celebrating 30 Years of Ocean Science

and Technology at the Monterey Bay

Aquarium Research Institute

March 2018

Ocean Observatories Initiative

June 2018

Ocean Warming

September 2018

Mathematical Aspects of Physical


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Oceanography | September 2017


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Contributing Writer

Cheryl Lyn Dybas


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Oceanography | Vol.30, No.3

In my previous column (June 2017) I

wrote about the history of ocean sciences

funding, focusing on the Ocean Sciences

Division at the US National Science

Foundation (NSF) as an example. It notes

long-term budget erosion, and suggests

that if we are going to reverse this trend,

we need to create a viable implementa-

tion plan that demonstrates the real value

of oceanography.

I firmly believe that ocean science and

technology are more important than ever.

We need to address ocean issues that

have worldwide consequence, including

the ocean’s role in climate change, sus-

tainability of environments and ecosys-

tems under human impacts, appropri-

ate long-term use of resources from the

sea, technology development and eco-

nomic opportunities related to the ocean,

the scientific basis for global security,

and other ocean-related issues that tran-

scend specific fields, agencies, or national

boundaries. It is time to put some ideas

on the table. It is time to make a plan.

So what should we do? First, we need

to start talking. I envision this conver-

sation as an expanded collaboration

between the United States and non-US

communities; there are ocean sciences

research assets in many countries. Just

as the high-energy physics community

leverages infrastructure among nations,

ocean sciences could, too (e.g., sharing

expensive assets like ships).

To be sure, ocean scientists have

worked across national boundaries for

decades—in this regard, scientists are

mostly apolitical and go where the inter-

esting problems lead them. We have

some good examples of large shared

efforts. These are mostly parallel fund-

ing efforts with trans-national coordina-

tion (e.g., Joint Global Ocean Flux Study,

World Ocean Circulation Experiment),

but there are some that have comingled

funds and co-supported facilities and

science implementation (International

Ocean Discovery Program). Nevertheless,

for the most part, national funds pay for

national programs, and these programs

are sometimes at least partially redun-

dant in various countries. Some redun-

dancy can be a good thing—replication of

results confirms significance of findings.

But we might think about how much

duplication of effort is really needed.

An implementation planning pro-

cess could encourage community build-

ing; support the development of early

career scientists; enhance interdisciplin-

ary, interagency, and international col-

laborations; and provide vehicles for con-

nections between government, academic,

and private-sector ocean sciences. We

need diversity of thought as we plan, and

this requires diversity of people; scien-

tists and stakeholders of all kinds in both

developed and developing nations must

be involved. An inclusive process will

increase access and effectiveness of ocean

science and technology on a global scale.

We already have a start at planning,

at least at the strategic level. For exam-

ple, the US National Research Council’s

Sea Change: 2015–2025 Decadal Survey

of Ocean Sciences (NRC, 2015) was com-

missioned by NSF in 2013 to review the

changing nature of ocean sciences and its

funding structures and to propose prom-

ising themes worth addressing in the

coming decade. Other nations have pub-

lished similar framework documents,

for example, in the UK, Scanning the

Horizon (Kennedy and Liss, 2013), and in

Europe, Eurocean 2020 (McDonough and

Calewaert, 2010). In order to implement

community goals, we must engage the

whole of the ocean science community

in an open, inclusive, bottom-up process.

My hope is that the global ocean sci-

ences community will not retreat in the

face of political and budget pressure

but instead will join together to craft a

synthesis of current knowledge and to

shape a productive future agenda with a

specific action plan. I hope we can encour-

age transdisciplinary innovation, with an

eye toward incorporating rapidly evolv-

ing technologies into rigorous scientific

frameworks. We need concrete mecha-

nisms for retaining early career scientists

and empowering them to envision the

future of the field. Universities can step

up to some extent in this area, acknowl-

edging the difficulty of starting careers on

“soft” (grant-funded) money. With a goal

of helping to encourage young scientists,

The Oceanography Society is putting its

policies where its mouth is, and now pro-

vides free membership to students and

reduced-cost membership to early career

scientists within three years of receiving

their PhD degrees.

Accomplishing bottom-up planning

demands time commitment. It requires

volunteers to step up and funding agen-

cies to cover costs. TOS is willing to part-

ner in facilitating a planning process—

as a first step, perhaps we can engage in

spirited discussion at this year’s upcom-

ing professional meetings worldwide.

Let’s get started!


Kennedy, H., and P. Liss. 2013. Scanning the

Horizon: The Future Role of Research Ships and

Autonomous Measurement Systems in Marine and

Earth Sciences. The Challenger Society for Marine

Science and the National Oceanography Centre

(NOC) Association, UK, 31 pp,

documents/about/2013_Scanning the Horizon.pdf.

McDonough, N., and J.-B. Calewaert, eds. 2010.

EurOcean 2010: Grand Challenges for Marine

Research in the Next Decade. Conference

Report and Ostend Declaration. Thermae

Palace, Oostende, Belgium, October 12–13,

2010. Belgian Science Policy Office (BELSPO),

Brussels. VLIZ Special Publication 49 Flanders

Marine Institute (VLIZ), Oostende, Belgium, 57 pp, belspo/northsea/publ/


NRC (National Research Council). 2015. Sea Change:

2015–2025 Decadal Survey of Ocean Sciences.

The National Academies Press, Washington, DC,

98 pp.,

Planning the Future of Ocean Sciences

Alan C. Mix, TOS President


Oceanography | September 2017

By Cheryl Lyn Dybas

The Jumbo

Carbon Footprint of a

Surf-and-Turf Dinner


What’s the carbon footprint of an average

shrimp-and-steak dinner?

If it comes from the conversion of man-

grove forests to aquaculture and agri-

culture, it’s 1,795 pounds of carbon diox-

ide. That’s about the same amount of

greenhouse gases produced by driving

a fuel-efficient car from Los Angeles to

New York City.

Clearcutting of tropical mangrove for-

ests to create shrimp ponds and cat-

tle pastures contributes significantly to

greenhouse gases and global warming,

according to findings reported in the May

2017 issue of Frontiers in Ecology and

the Environment.

“The results mean that 1,603 pounds

of carbon dioxide are released for every

pound of shrimp, and 1,440 pounds of

carbon dioxide for each pound of beef”

from mangrove forest conversion, says

J. Boone Kauffman, an ecologist at Oregon

State University who led the project.



Those numbers were obtained with a

new measurement called the land-use

carbon footprint. It records the amount of

carbon stored in an intact mangrove for-

est, the greenhouse gas emissions from

conversion of that forest to aquaculture

or agriculture, and the quantity of the

shrimp or beef produced over the life of

the land’s use.

“What we found was astounding,”

Kauffman says. “When you convert man-

grove forests to shrimp ponds or cattle

pastures, a remarkable amount of car-

bon is being emitted into the atmosphere.

And the food productivity of these sites

is not very high.”

Scientists have the difficult task of clearly

conveying the ecological consequences

of forest and wetland losses to the pub-

lic, state Kauffman and coauthors in their

Oceanography | Vol.30, No.3

Frontiers in Ecology and the Environment

paper. “To address this challenge, we

scaled the atmospheric carbon emissions

from mangrove deforestation down to the

level of an individual consumer.”

The study was conducted on 30 rela-

tively undisturbed mangrove forests  and

21 adjacent shrimp ponds or cattle pas-

tures. The sites were in Costa Rica, the

Dominican Republic, Honduras, Indonesia,

and Mexico. Shrimp ponds were sampled

in all countries except Mexico, where the

predominant land use was conversion to

cattle pastures.

On the basis of measurements from

these locations, “we determined that

mangrove conversion results in GHG





between 1,067 and 3,003 megagrams of

carbon dioxide equivalent per hectare,”

says Kauffman.

The decline in carbon storage from man-

grove conversion to shrimp ponds or cat-

tle pastures exceeded the researchers’

original estimates.

Mangroves represent less than 1% of

the world’s tropical forests, scientists have

found, but their degradation accounts

for as much as 12% of the greenhouse

gas emissions that come from tropical



Enter a mangrove forest. In this dark

water world, trees with twisted limbs live

double lives—one foot on land, the other

in the sea.






also called mangals, thrive in saline

coastal habitats in the tropics and sub-

tropics. All take root in waterlogged

soils where slow-moving currents allow

sediment to accumulate.

Red, black, and white mangrove trees,

along with buttonwoods, may grow along

the same shoreline. Where these species

are found together, each stakes out a spot.

Red mangroves are closest to the sea’s

edge; their prop roots extend into the

water from branches above. The roots

capture sediment, stabilizing the shore.

Farther inland are black mangroves with

pneumatophores pointing upward from

the soil. Pneumatophores supply oxygen

in otherwise anaerobic sediments.

White mangroves, with no special root

adaptations, are found in the interior man-

grove forest, followed by buttonwoods in

the upland transition area.

These forests-of-the-tide collectively

cover a worldwide area of 53,190 km2

in 118 nations—about 0.6% of all tropical

forests. And that number is dropping.

Rates of mangrove deforestation over

the past three decades have been dra-

matic, says Kauffman. “Mangroves are

disappearing at the rate of about 1% per

year.” In places such as Southeast Asia,

mangrove conversion to shrimp ponds

is the greatest cause of these intertidal

forests’ decline.



Mangroves provide ecosystem services

worth up to $57,000 USD per hectare

per year and collectively sustain more

than 100 million people, according to the

United Nations Environment Programme

report The Importance of Mangroves:

A Call to Action.

The report estimates that deforestation

of the world’s mangroves results in annual

economic damages of up to $42 billion.

From top to bottom: (1) Denuded mangrove forest in Madagascar. (2) Shrimp harvested from

an Indonesian shrimp farm. (3) Shrimp pond in Brazil. Courtesy of J. Boone Kauffman, Oregon

State University

Oceanography | September 2017

Oceanography | September 2017

Mangroves’ most important ecosystem

service, scientists say, may be mitigating

climate change by removing greenhouse

gases from the atmosphere. Like other

plants, mangroves capture carbon diox-

ide and store it in their leaves, roots, and

trunks (biomass) and in the soil. But unlike

most other forests, mangroves do not

have a maximum storage capacity. They

continuously amass carbon in soil, where

it can remain for millennia.

Mangroves are extremely productive

ecosystems that can increase their bio-

mass relatively quickly, trapping more car-

bon than other forest types. The upper

meters of mangrove soils are primarily

anaerobic—missing the organisms that

decompose organic material and release

carbon into the environment.

How much “blue carbon”—carbon cap-

tured by the world’s coastal and ocean eco-

systems—is stored in mangrove forests?

Researchers mapped mangroves and

identified which ones contain the most

blue carbon: mangals in Sumatra, Borneo,

and New Guinea, and along the coasts of

Colombia and northern Ecuador.

The findings were published in 2013

in the journal Conservation Letters. The

results can help guide decisions about pri-

ority areas for mangrove conservation and

rehabilitation, scientists say.

When mangrove forests are converted

to agriculture or to aquaculture ponds,

the majority of the carbon in their bio-

mass and underlying soils is released into

the atmosphere, joining other sources of

greenhouse gases. Clearing even small

tracts of mangroves generates high vol-

umes of carbon dioxide.

“These forests have been absorbing

carbon for the last 4,000 or 5,000 years,

but now through deforestation they have

become significant sources of green-

house gas emissions,” Kauffman says.

“Because they store so much carbon,

they’re important sites for mitigating or

slowing climate change.”



An important question, say Kauffman and

coauthors, is whether the value of the

shrimp or beef produced from a former

mangrove forest exceeds the value of the

ecosystem services lost as a result of man-

grove conversion. Those ecosystem ser-

vices include maintaining high biodiversity,

fisheries production, protection against

storms and erosion, and carbon storage.

“Addressing this trade-off is the respon-

sibility of governments and is the personal

choice of the consumer, who should have

access to information on the true costs

and impacts of food production,” the

researchers write.

“A better understanding of land-use

carbon footprints would provide context

to make informed decisions about how

our everyday lives affect land use and

climate change.”

And whether that surf-and-turf dinner is

worth the price—in mangrove currency.

Cheryl Lyn Dybas (, a Fellow of the International League of

Conservation Writers, is a contributing writer for Oceanography and a marine ecologist by training.

She also writes about science and the environment for National Geographic, BioScience, Ocean

Geographic, Canadian Geographic, National Wildlife, Yankee, and many other publications.

Background photo: Women in the Sundarbans

mangrove forest, Bangladesh. From top to

bottom on left: (1) Brazilian fisher with a man-

grove forest in the background. (2) Abandoned

fish pond showing mangrove devastation.

(3) Dried-up shrimp pond in Brazil. Courtesy of

J. Boone Kauffman, Oregon State University

Oceanography | Vol.30, No.3

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