Pursuing underwater pipe dreams: collecting sediment cores from Moorea’s coral reefs

Originally published on the ReefBites Blog

Written by Erin Dillon

What do you get when you combine a three-meter-long piece of aluminum irrigation pipe, a fence post driver, an old pipe clamp, and a motley crew of scientific divers? Quite a lot, it turns out.

We were twelve meters deep on a fringing reef along the northern coast of Moorea, a French Polynesian island in the South Pacific, braving bad weather and blinding plumes of swirling silt to unravel the history of these reefs. We hammered relentlessly, trying to hold the pipe perfectly upright as it crept, centimeter by centimeter, deeper into the sediment (Fig. 1). Excitement coursed through usas the pipe slid further and further down into the matrix of sediment and dead branching coral. We held our breaths (figuratively speaking; don’t worry, diving safety officers), hoping that the core barrel would not hit a large coral head and get stuck. We hammered and hammered, the air left in our tanks being the only limiting factor.

Figure1. Pounding the core barrel into the substrate, surrounded by clouds of silt.Photo credit: Aaron O’Dea

Pounding the core barrel into the sand was challenging, but pulling it out was even harder. We curled ourselves awkwardly around the pipe and twisted and tugged until finally the core was free. This core would give us a chronology of the reef over the last several hundred years, pre-dating modern monitoring efforts and major human impact in the region.

After over 20 hours of dive time as well as significant lifting, paperwork, and logistical maneuvering, we tallied up our spoils – around 650kg of sand. These samples were then shipped on pallets over 6700km to our lab in California, where they will be processed and carefully examined with a microscope to yield a tiny treasure trove of shark dermal denticles, fish teeth, otoliths, urchin spines, sponge spicules, foraminifera, and coral fragments – each piece a window into the past. Together, these remnants, contextualized by high precision coral dating, allow us to reconstruct how these coral reefs have changed over time alongside Moorea’s human history. I’ll be spending my days counting and classifying the shark dermal denticles (Dillon et al. 2017) to explore how shark communities shifted in size and composition over time on islands with different levels of human impact and settlement histories (Moorea as compared to Tetiaroa and Rangiroa). At the same time, some of my colleagues in the lab will be teasing apart patterns in the number and types of fish otoliths and teeth, particularly those belonging to important reef herbivores. Our coring work on Moorea is one piece of this larger puzzle, but it all begins with countless meters of pipe, ambition, and a lot of heavy lifting.

References

Dillon E, Norris R, O’Dea A (2017) Dermal denticles as a tool to reconstruct shark communities. Mar Ecol Prog Ser 566:117–134. http://dx.doi.org/10.3354/meps12018.

 

Huai-Hsuan May Huang

STRI Fellow and PhD candidate at the University of Hong Kong

X371logo.jpgI am a micropaleontologist with a specialty in marine ostracods. I did my PhD in the University of Hong Kong. I love being on a research vessel, searching for answers in the vast ocean, and working with many scientists from diverse backgrounds. I am broadly interested in how species originated, distributed or went extinct in response to paleoenvironmental changes. Ostracods is a large class of bivalved crustaceans with a wide variety of ecological preferences, and is useful in paleoecological studies. In the STRI, I will be reconstructing the ostracod faunal changes during the emergence of the Panama Isthmus to shed light on the vulnerability of benthic meiofauna to environmental shifts.

www.researchgate.net/profile/Huai_Hsuan_Huang

Note: May will soon defend her Phd in the lab of Moriaki Yasuhara

 

Jon Cybulski

STRI Fellow and Ph.D. candidate University of Hong KongJon_diving_2.jpg

Presently, I am a Ecology and Biodiversity Ph.D. candidate in Dr. David Bakers Coral Biogeochemistry lab at the University of Hong Kong, Swire Institute of Marine Science. My dissertation research focuses on one simple overarching theme: What were coral assemblages like during Hong Kong’s past? To answer this, my work combines classical paleo and historical ecology techniques to collect marine sub-fossils, characterize their diversity changes, and then I use various biogeochemistry methods to extract isotopic information and see what stressors have been impacting them through time.

While in Panama in the O’Dea lab, I will be studying coral sub-fossils collected in push-cores from the Pacific side of Panama. Through species identification and taphonomic analysis, I hope to determine if a mid-Holocene high stand (a period in the past few thousand years with slightly higher mean sea levels) occurred in Panama. If a highstand did occur, I want to know what it can tell us about future sea level projections over the next 100 years due to anthropogenic climate change. In this way, we may be able to get a better understanding of what impacts sudden sea level changes have on coral communities, and what we can do to protect and give them a chance for survival.

Besides rocks and old dead things, I love weightlifting, playing sports, going on any type of outdoor excursion, brewing beer, or reading epic fantasy novels.

Panama was an ocean, will it be again? [Panamá fue una vez un océano, ¿lo será de nuevo?]

 

Published first in La Prensa 17 December 2018

O'Dea 2018 Panama era Mar 17 December La Prensa

Hace millones de años, donde se encuentra ubicada la angosta franja de tierra que hoy en día llamamos Panamá, había un océano profundo. Cuando se formó el istmo, se desencadenó una cascada de eventos globales. Mirando hacia el futuro, el istmo podría volver a jugar un papel importante en el cambio global.

Cuando esta historia empezó, los continentes de América del Sur y del Norte, África, Asia, Australia, y la Antártida, formaban un solo “supercontinente”, llamado Pangea.

Hace aproximadamente 150 millones de años, Pangea comenzó a fragmentarse, formándose el Océano Atlántico. A la vez, una pequeña vía marítima se abrió, conectando el joven y angosto Océano Atlántico con el enorme Océano Pacífico. Esta vía se encontraba justo donde está Panamá actualmente y fluyó entre el Pacífico y el Atlántico durante los siguientes 125 millones de años, permitiendo el libre movimiento de animales marinos.

Más recientemente, hace solo 25 millones de años, una franja de volcanes submarinos en el océano Pacífico chocó con América del Sur a la altura de Panamá. Los volcanes más altos emergieron como islas, transformando la vía marítima en varios estrechos de menos profundidad. Los fósiles de Panamá muestran que estas islas volcánicas estaban cubiertas de exuberante vegetación y rodeadas de arrecifes de coral llenos de peces.

Poco a poco, las rocas del fondo del mar comenzaron a subir hacia la superficie, convirtiéndose lentamente en un puente terrestre que volvió a conectar América del Sur y del Norte. Este evento monumental tomó más de 20 millones de años.

¿Cuándo fluyó la última gota de agua salada entre los dos océanos? Los científicos están de acuerdo en que el puente terrestre completamente formado surgió hace apenas 3 millones de años, casi ayer desde la perspectiva de un geólogo.

Impacto

¿Por qué el mar es azul en el Caribe, pero turbio y a veces frío en el Pacífico? ¿Por qué no hay playas de arena blanca a lo largo del Pacífico? ¿Por qué hoy día el Caribe es tan diferente del Pacífico? Estas diferencias enormes entre los océanos se deben a la presencia del istmo.

Los impactos de la formación del istmo también se sintieron mucho más allá de Panamá. Las corrientes oceánicas se desviaron, muchos animales se extinguieron, y hubo repercusiones en el clima y la biodiversidad del planeta entero.

DSC_3851_2

El puente creado por el istmo facilitó el movimiento de plantas y animales entre los dos continentes americanos. Las llamas y alpacas, icónicas de los Andes, son descendientes de camellos que migraron desde el norte hacia Sudamérica por medio del istmo.

Y la migración continúa hasta nuestros días: el coyote se dirige hacia el sur, mientras que el capibara se mueve hacia el norte.

El nuevo puente también formó una barrera: los animales marinos ya no podían moverse entre los océanos. Sus poblaciones se dividieron en dos. Científicos de todo el mundo usan este evento como el momento “cero” en un reloj para medir cuánto tiempo tardó para que evolucionen nuevas especies.

La historia de esta pequeña franja de tierra que cambió el mundo coloca nuestra propia existencia en el planeta en un contexto de humildad.

Pero, ¿hacia dónde vamos en el futuro? Los geólogos predicen que eventualmente el Istmo de Panamá va a separarse y flotar hacia el Caribe. Otro océano profundo pudiera conectar el Pacífico con el Atlántico nuevamente. Pero no se preocupen, esto no sucederá antes de unos 20 millones de años.

Sin embargo, hay algo de lo que sí deberíamos estar muy preocupados. El aumento de las emisiones de dióxido de carbono (CO2) a través de la quema de combustibles fósiles para el transporte y la producción de energía, la agricultura industrial y la pérdida de los bosques está alterando el curso de la historia de nuestro planeta.

Mientras que los océanos y la atmósfera se están calentando, los glaciares (algunos de los cuales tienen un espesor de más de 5 km) se están derritiendo, haciendo subir los niveles del mar debido al ingreso de agua dulce del deshielo. A medida que el mar se calienta, también se expande, elevando aún más su nivel.

Desde la revolución industrial, el nivel del mar ha aumentado alrededor de 26 cm y las predicciones sugieren otro metro por encima de eso en el próximo siglo. Curiosamente, no todas las partes del océano se están subiendo por igual. De hecho, el lado caribeño de Panamá está acelerándose más rápido que el promedio mundial. Los científicos todavía están tratando de entender por qué esto es así, pero es un hecho innegable.

Y es un hecho desalentador para lugares como la ciudad de Colón. Colón se construyó cerca del nivel del mar hace más de 150 años para satisfacer la demanda de la “fiebre del oro” en California. Las inundaciones recientes se deben principalmente a un sistema de drenaje envejecido y mal mantenido: el agua no puede salir lo suficientemente rápido al mar. Con un metro adicional de nivel del mar significa que no solo muchas partes de la ciudad estarán bajo agua marina, sino que los afortunados que se encuentren en terrenos ligeramente más altos también serán más difíciles de drenar.

Es una verdadera receta para el desastre, para la ciudad que una vez fue resplandeciente.

Cuando se construyó Colón, nadie podría haber predicho el aumento del nivel del mar. Ahora es diferente. Con una gran cantidad de datos científicos podemos predecir y podemos actuar.

Al oeste de Colón nos encontramos el archipiélago de Bocas del Toro. En 1991 Bocas fue golpeado por un tsunami que llevó agua marina a 200 m dentro de las calles del pueblo. Si volviera a ocurrir un tsunami similar, el hecho de que el nivel del mar sea más alto ahora de lo que era hace 27 años significa que sería más destructivo y catastrófico para la vida humana y las construcciones.

Al este, los gunas, que habitan el archipiélago de San Blas, ya están sintiendo los efectos del aumento del nivel del mar. Sus islas de belleza inigualable estarán entre las primeras en el mundo en extinguirse por el calentamiento global. Los países y Estados que han estimado los costos financieros de mitigar y responder al aumento del nivel del mar muestran que el precio será extremo, pero pocos están considerando los incalculables impactos culturales y sociales.

¡No piense que el lado pacífico del istmo será inmune a estos peligros! Solo pequeñas cantidades de aumento en el nivel del mar aumenta las posibilidades de inundaciones durante las mareas de tormenta. Tocumen, Costa del Este y otras tierras bajas serán muy propensas, más ahora que han perdido muchos manglares, que funcionaban como escudo protector.

Alternativas

Sin embargo, la ciencia nos informa de cambios que se pueden introducir para mitigar el calentamiento global. Panamá ya ha tenido un impacto increíblemente positivo en la reducción de las emisiones de CO2, ya que el canal evita que los barcos tengan que viajar por Sudamérica, lo que ha salvado la emisión de 700 millones de toneladas de dióxido de carbono a la atmósfera. No está mal para una pequeña franja de tierra y una zanja.

Pero no debemos ser complacientes. La Organización Marítima Internacional afirma que, sin intervención, las emisiones de carbono por actividades marítimas en el mundo podrían aumentar hasta 250% para 2050.

La industria del transporte marítimo cuenta con una gran cantidad de investigaciones para mejorar la eficiencia de los barcos, especialmente cuando un aumento en la eficiencia de combustión de solo un pequeño porcentaje puede resultar en ahorros financieros significativos que alcanzan los millones de dólares.

Los avances tecnológicos son una parte importante de la solución, especialmente en el diseño del casco, las nuevas fuentes de combustible y las mejoras del motor, pero igualmente importante es la introducción de mejores medidas operativas, como la adopción de “vapor lento” y la mejora de la logística a bordo y en los puertos, que puede tener impactos sorprendentemente grandes en la eficiencia y, por lo tanto, desempeñar un papel importante en la reducción de emisiones a nivel mundial.

Nuestras elecciones de estilo de vida también son importantes. Por ejemplo, la compra de productos cultivados localmente no solo ayuda a los agricultores locales, sino que también evita la necesidad de transportar productos refrigerados en barcos a alta velocidad; una de las formas de transporte más contaminantes.

América Latina y el Caribe dependen en gran medida del transporte marítimo, y es donde se realiza más del 90% de todos los movimientos internacionales de carga, una gran proporción de los cuales utiliza el Canal de Panamá.

Tenemos la responsabilidad de aprender del pasado para mejorar nuestro futuro. Hace millones de años, el pequeño istmo de Panamá jugó un papel increíble en la conducción de los cambios en el mundo. Aunque Panamá es pequeño, tiene la bendición de estar en una posición privilegiada para seguir ayudando a bajar las emisiones contaminantes y, una vez más, desempeñar un papel importante en un cambio positivo para nuestro planeta y para las poblaciones costeras, que serán las más afectadas por el aumento del nivel del mar.

Publicado por La Prensa: https://impresa.prensa.com/vivir/Panama-vez-oceano-nuevo_0_5192480746.html

Old dogs and new tricks

By Beth King, STRI

Discoporella close up
Close-up of the millimetre sized individual zooids of a colony of Discoporella

A quick look at the fossil record shows that no species lasts forever. On average, most species exist for around a million years, although some persist for much longer. A new study published in Scientific Reports from paleontologists at the Smithsonian Tropical Research Institute in Panama shows that young species can take advantage of new opportunities more easily than older species: a hint that perhaps older species are bound to an established way of life.

“We’re lucky to live and work in Panama where nature has set up its own evolutionary experiment,” said Aaron O’Dea, STRI paleontologist. “When the Caribbean Sea was isolated from the Pacific Ocean by the slow uplift of the Isthmus of Panama, nutrient levels fell and Caribbean coral reefs proliferated. We can use the excellent fossil record to observe how Caribbean life responded to this environmental and ecological transformation.”

The team’s best choice for tracking the change was a peculiar family of marine animals known as the cupuladriid bryozoans. These relatively small animals consist of unusual, free-living, disc-shaped colonies of individuals called zooids. “Colonies form through sexual reproduction or asexually by cloning, as bits of the colony break off and continue to grow,” said STRI post-doc and coauthor Blanca Figuerola. “They abound on the sea floor along the continental shelf across the tropics, filtering plankton from the water via a beautiful waving crown of tentacles. When colonies die, their hard skeletons remain, and are exceptionally abundant as fossils.”

O’Dea’s group collected and identified more than 90,000 cupuladriid colonies from 200 fossil samples and 90 more recent samples collected by dredging the sea floor. The samples contained mud, sand, coral remains and other indicators of the kind of habitats where the bryozoans had lived. The team measured the abundances of the 10 most common species along gradients of these environmental and ecological indicators.

“We were intrigued to find that, even though all species could expand into the new Caribbean habitats created after final formation of the Isthmus, different species did so at different speeds,” said O’Dea. “The patterns were clear—old species that originated before 8 million years ago took 2 million years longer to expand into the new habitats than the younger species.”

“Perhaps younger species, which have smaller populations, are less tied to their history,” said former STRI post-doc and University of Saskatchewan researcher Santosh Jagadeeshan, another co-author. “Old species, with large, settled populations may be less able to escape from established roles and defined environmental tolerances because they mate with each other creating a high gene flow that makes it hard for genes for new traits to become established. It seems you can’t teach an old dog new tricks in evolution, either.”

The study was funded by Panama’s National Bureau of Science, Technology and Innovation, SENACYT, Panama’s National System of Researchers (SNI), the U.S. National Science Foundation (NSF), the Smithsonian Institution, STRI, the National Geographic Society and Mr. Josh Bilyk.

O’Dea, A., De Gracia, B., Figuerola, B. and Jagadeeshan, S. 2018. Young species of bryozoans occupied new Caribbean habitats faster than old species. Scientific Reports, DOI: 10.1038/s41598-018-30670-9

colony-coloured-inset-emerging-colony
Stiff setae extend away from the edge of cupuladriid bryozoan colonies, and work in synchrony to allow the colony to “walk” over the sea floor and emerge from the sediment when buried

¿A dónde se fueron las playas blancas?

isla grande donde se fue la playaLas imágenes satélite de 2009 (arriba) y 2016 (abajo) muestran la pérdida completa de la hermosa y valiosa lengua de arena blanca en Isla Grande.

Llegué a Panamá por primera vez en 1998. En esta época era un joven estudiante y me atraía y fascinaba la vida marina en ambos lados del istmo. Era mi primera vez en las Américas y toda era una aventura. Sobreviví a tres cosas: a una disentería en Bocas del Toro, al atropello por un taxista en la ciudad de Panamá y a la caída de un coco sobre mi cabeza en Isla Grande, Provincia de Colón. Salí del país prometiendo nunca volver. Pero, como dije al principio, Panamá goza de una extraordinaria vida marina que cautiva al primer contacto con ella. No hace falta decir que ahora hace ya 16 años que vivo en Panamá con mi familia panameña.

En esa primera visita a Isla Grande, en la zona llamada Costa Arriba, me encontré con una exquisita extensión o lengua de arena blanca que iba desde la esquina suroeste de la isla a más de 150 metros hacia mar adentro. En esta época, buceé con una dinastía de peces brillantes; en la noche dormí sobre las blancas y suaves arenas de la playa, que imaginaba como una gran cama de harina. Hoy día, la playa se ha ido y no hay peces. ¿Qué ocurrió?

La erosión de la playa es un proceso natural que ha ocurrido durante miles de años, en donde la arena es arrastrada por la acción de la lluvia o las olas, y es reemplazada por arena nueva, algunas veces más, algunas veces menos, por lo que la playa cambia de forma. Entonces, ¿por qué las arenas no regresaron a Isla Grande?

La respuesta es bastante interesante y algo desconcertante. Resulta que la suave harina blanca que nos encanta en nuestros pies en realidad está hecha de pequeños pedazos de coral que fueron comidos y luego defecados por animales como los peces loro. Sí! Las playas blancas del Caribe están hechas de excremento de peces. Algunos científicos han estimado que un solo pez loro puede producir una increíble tonelada de arena en un año. ¿Cómo lo midieron?, no les pregunté!

Por consiguiente, cuando se eliminan los peces loro del arrecife por la sobrepesca, llega un momento en que la arena erosionada es mayor que la arena que se forma, y la playa desaparece rápidamente. No más peces, no más playa. Agregue a eso el impacto de la contaminación y el calentamiento global sobre los corales, y tendremos una receta perfecta para el desastre.

El resultado no solo se muestra en imágenes de satélite, sino también en los recuerdos de quienes alguna vez disfrutaron de estas playas espectaculares. Las personas en las comunidades costeras desde Bocas del Toro hasta los Cayos de Guna Yala, están viendo desaparecer sus playas de arena blanca.

¿Cómo lo detenemos? En papel es sencillo: mejorar la salud de los corales y aumentar el número de peces loro; y las playas volverán. En la práctica, podemos buscar historias de éxito en otros lugares del caribe. En Punta Cana, República Dominicana, conocen el valor económico de sus playas de arenas blancas. Estimaron que con cada metro de playa perdida, el país pierde más de 300,000 dólares en ingresos del turismo cada año (Wielgus et al. 2010). En Punta Cana establecieron zonas dónde estaba prohibido pescar que permitieron la recuperación del pez loro y en consecuencia de los arrecifes. También, emprendieron una fuerte campaña para cultivar nuevos corales donde anteriormente existían. Es un modelo que tiene sentido desde el punto de vista comercial y podría aplicarse en cualquier parte del mundo si cuenta con una iniciativa correcta y regulada. Las playas de Panamá son un tesoro nacional que vale muchos millones de dólares en turismo. Son una protección frente al aumento del nivel del mar y a las tormentas como el infrecuente, pero mortal, huracán Otto. Brindan refugio a la vida marina y alimentan a las comunidades locales. Pero más que esto, se suman inexorablemente a la calidad de vida a todos.

Al saber cómo se forman estas playas podemos entender mejor porque se están perdiendo. Eso nos ayuda a tomar decisiones más efectivas que traerán de vuelta las hermosas playas del Caribe, para así apoyar la economía futura de las comunidades locales y el disfrute de todos.

Get your optimism from the past

When we think about a “pristine” untouched ecosystem we often have a single, preconceived image in mind. It could be a grassland with thousands of bison, a thick tropical forest, or a coral reef teeming with fish and sharks. These places certainly existed, and in many cases are now lost or replaced by alternatives, but there has always been variation and not everywhere would fit into these limited boxes. There must always have been marginal ecosystems and vast amounts of variation.

It is this variation that we propose can help conservation. If we can describe that variation we can do a better job at placing modern ecosystems into context. In this paper published in Conservation Biology we discuss our ideas of how the fossil record can be used to redefine what should be considered “pristine” and the positive benefits of doing so for conservation.

Open Access available

O’Dea, A., M. Dillon, E., H. Altieri, A. and L. Lepore, M. (2017), Look to the past for an optimistic future. Conservation Biology. doi:10.1111/cobi.12997

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Building Bridges

As the debate on the age of the Isthmus of Panama matures we respond to an eLetter.

Taken from Science Advances

8 November 2016

We thank Erkens and Hoorn for their constructive comments. Like us, they believe that collaboration between biologists, geologists and paleontologists focusing on data and analyses is required to unravel the history of the Isthmus of Panama. We agree with Erkens and Hoorn that the Continue reading

Historical records reveal that Caribbean coral reefs grow faster with more parrotfishes

screen-shot-2017-02-08-at-23-23-27Caribbean coral reefs have transformed into algal-dominated habitats over recent decades, but the mechanisms of change are unresolved due to a lack of quantitative ecological data before large-scale human impacts. To understand the role of reduced herbivory in recent coral declines, we produce a high-resolution 3,000 year record of reef Continue reading

Formation of the Isthmus of Panama

The formation of the Isthmus of Panama stands as one of the greatest natural events of the Cenozoic, driving profound biotic transformations on land and in the oceans. Some recent studies suggest that the Isthmus formed many millions of years earlier than the widely recognized age of approximately 3 million years ago (Ma), a result that if true would revolutionize our understanding of environmental, ecological, and evolutionary change across the Americas. To bring clarity to the question of when the Isthmus of Panama formed, we provide an exhaustive review and reanalysis of geological, paleontological, and molecular records. These independent lines of evidence converge upon a cohesive narrative of gradually emerging land and constricting seaways, with formation of the Isthmus of Panama sensu stricto around 2.8 Ma. The evidence used to support an older isthmus is inconclusive, and we caution against the uncritical acceptance of an isthmus before the Pliocene.

pdf of the paper

isthmian pairs

New opportunities in the O’Dea lab

We are looking for three new interns/fellows to join the O’Dea lab. For more information download the flyers here: opportunities in the O’Dea lab

Project 1 (one position). Interoceanic differences in energy flow. Position open now, send CV and cover letter to odeaa@si.edu.

Project 2 (two positions). The ecological, life history and environmental differences between Holocene and modern Caribbean coral reef fish assemblages using fossil otoliths. To apply follow directions on the flyer.

Isthminia panamensis: the 6 million year old marine ‘river’ dolphin

isthminia panamensis SI

Four years ago Panamanian student Dioselina Vigil discovered a fossil in rocks near the small town of Piña. It turned out to be more than a bunch of bones. After careful preparation under the careful guidance of Smithsonian marine mammal paleobiologist Nicholas Pyenson and his team, the amazing fossil skull, replete with most of its teeth, was revealed to be a new genus of ‘river’ dolphin which we named Isthminia panamensis.

Isthminia, now an extinct lineage, is the closest relative of the Amazon river dolphins but was found in rocks that were deposited in open ocean just 6 million years ago. In this context the evolution of the river dolphins’ ecological shift from the sea to river becomes just a little clearer.

We are extremely proud that all aspects of the study are open-access. 3D models are available from the Smithsonian’s X 3D site for anyone to download, print and study. The paper itself is published in the open-access journal PeerJ. We even made all reviews available to read in this increasingly popular model for publication and divulgation. A 3D print of the specimen is on display at the Panama’s Biomuseo, and I even have a 3D print of the fossil in my lab.

Get the article here, play around with the 3D models and print out your own Isthminia panamensis

Teasing apart the drivers of extinction over 500 million years

From colleague and friend Paul Harnik’s Paleolab Blog: “How does environmental change shape the relationships between ecological traits and extinction risk? The fossil record is an invaluable resource for answering such questions. In a paper now available early online in the journal Global Change Biology, my collaborators and I show that over the last 500 million years global environmental and geochemical changes have had remarkably little effect on the relationship between geographic range size and extinction risk among marine mollusks. In other words, clams and snails with small geographic ranges have been at elevated risk of extinction throughout their evolutionary history regardless of broad-scale environmental conditions. In contrast, we found that mollusks that live in (rather than on) sediments on the seafloor tended to be at lower risk during times of warmer climate.”

Paper hereScreen Shot 2015-09-10 at 09.24.55

Natural History of the Isthmus of Panama

Felix Rodriguez and I just published a compendium of papers in Spanish for students and non-scientists in Latin America. The book is called “Historia natural del Istmo de Panama” and features a suite of papers covering different topics from the geology of the Isthmus to the future of fishing along both coasts of Panama. The book will be on sale across the Isthmus. Let me know if you wish to purchase a copy.

My contribution can be downloaded here: Historia natural de los mares panameñosbook-HistoriaNat-mod

Can spicules be used to reconstruct ancient sponge communities?

Anyone that has played with coral reef sand has felt the sharp needles of sponge spicules  in their hands. Spicules are made by sponges (and other animals too, like some ascidians) and are like glass. In fact they are glass, being made of pure silica, and they are used by sponges as defense from chomping fish or to help keep the sponge rigid. They come in an amazing variety of shapes and sizes, and the sands of coral reefs can be filled with billions of spicules.

Sponges are very important for reefs. They filter huge quantities of water keeping things clear and clean, provide important homes for loads of other animals, and they protect reefs from erosion by binding the reef together. But, as with most of life in the Caribbean, sponge communities have started to deteriorate. Since the 1980’s they have become less abundant and less diverse. Without sponges reefs may just wash away.

We wish to explore the historical changes in Caribbean reef sponge communities. When did sponges decline and why? The coring project of the TMHE will be exploring sponge spicules through the last few thousand years in several Caribbean reefs (see here). However, spicules are strange beasts. Some sponges produce millions of spicules, others hardly any or none at all. Spicule shape is highly variable (see image) but is not tightly phylogenetically constrained. That means that some spicule types occur in unrelated groups. What’s more, some sponges have more than one type of spicule, sometimes three or four.

This all makes it extremely difficult to reconstruct the sponge community from a bunch of spicules. In this paper student Magdalena Lukowiak at the Polish Academy of Sciences who had held a short term fellowship at STRI explores the taphonomy of sponge spicules on a Caribbean reef in Bocas del Toro. The relationships between sponge community and spicules found on the sea floor explored in this paper will help us to resolve changes in sponge communities through our cores.

Download the paper by clicking on the image

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What drives change in the seas?

What drives major ecological and evolutionary changes in the seas? To explore this question we documented changes in the abundance of different clams in the Caribbean over the past 11 Myr.

The structure of clam communities shifted dramatically with an increase in the abundance of attached epifaunal bivalves and a decrease in infaunal bivalves. This was driven by the proliferation of coral reefs, ultimately caused by the closure of the Isthmus of Panama.

These data provide a classic case of proximate and ultimate drivers of evolutionary change. Jill Leonard-Pingel was lead author. Pdf forthcoming….

Extinctions in ancient and modern seas

In the coming century, life in the ocean will be confronted with a suite of environmental conditions that have no analog in human history. Will marine species adapt or go extinct?

The last two years I have been involved in a dynamic working group called “Determinants of extinction in ancient and modern seas” led by Paul Harnik, Rowan Lockwood and Seth Finnegan and funded by NESCent. The aim of the working group is to use the history of life as preserved in the fossil record to help make better predictions about where life is heading in the future, especially in view of the looming sixth mass extinction.

We have just published our first paper in Trends in Ecology and Evolution. The study compares the patterns, drivers, and biological correlates of marine extinctions in the fossil, historical, and modern records and evaluates how this information can be used to better predict the impact of current and projected future environmental changes on extinction risk in the sea.

Download the pdf of the paper by clicking on the image.

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Cenozoic seawater Sr/Ca evolution

Records of seawater chemistry help constrain temporal variations in geochemical processes that impact the global carbon cycle and climate through Earth’s history. Here we reconstruct Cenozoic seawater Sr/Ca using fossil Conus and turritellid gastropods.

Our favored seawater Sr/Ca scenarios point to a significant increase in the proportion of aragonite versus calcite deposition in shelf sediments from the Middle Miocene, coincident with the proliferation of coral reefs. We propose that this occurred at least 10 million years after the seawater Mg/Ca threshold was passed, and was instead aided by declining levels of atmospheric carbon dioxide.

Pdf of the paper available by clicking on these images of cone shells…

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image from http://www.coneshell.net

A review of the zooid size MART approach

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As a PhD student I devised and developed a completely new technique for investigating paleoseasonality. Reconstructions of paleoenvironments often fail to understand the importance of the mean annual range of temperature (MART) in both oceanographic and biological contexts. The new technique, called the ‘zooid size approach’ makes use of the temperature-size rule in colonial bryozoans to estimate MART. The temperature-size rule is a universal phenomenon that states that body size decreases as temperature increases.

At the time, our understanding of the temperature-size rule was rudimentary and it was necessary to develop hypotheses on the mechanisms behind the rule and then test them under controlled culture and natural experiments, before finally applying the approach to fossil bryozoans to estimate MART’s in ancient seas.

The original paper published in 2000 presenting the technique can be downloaded here.

Now 10 years later with my ex-Phd supervisor Beth Okamura we review the approach along with the growing body of work that has since been published on the theme. We consider the general issue of why body size varies with temperature, explore the limitations of the approach and highlight its advantages relative to other proxies for palaeotemperature inferences.

Download the pdf of this new paper by clicking on the image.

What happened at the end of the Cretaceous?

Even genetically identical animals can look very different if they grow and live in different environments. Think ‘you are what you eat’. I make use of this phenomenon to try to reveal changes in environments in the deep past by first understanding what drives change in morphology in the animals in question and then measuring that morphology in fossils through time.

I applied this paradigm to one of the most studied and certainly most discussed events in the history of life on earth. The K-T (Cretaceous-Tertiary) boundary, 65 million years ago and the demise of the non-avian Dinosaurs and a suite of other animals and plants in the seas and on land. I made detailed measures of morphology in a number of fossil bryozoans in a beautiful K-T section of chalk in Denmark.

Rapid and repeated changes in morphology suggest that there were a suite of environmental changes in the last few thousand years just before the K-T boundary.

Although we dont explore the causes of the extinctions, or the ‘smoking gun’, these results are important for a full understanding of the complex changes associated with major extinctions observed to occur around the world. Click on the image for the pdf.

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Sex in the Caribbean

Evolutionary success was determined by mode of reproduction in cupuladriid bryozoans: Closure of the Panama Isthmus 3 million years ago led to a rapid reduction in primary productivity across the Caribbean. In response, cupuladriid bryozoans underwent a major transition, with evolutionary winners and losers dictated by how much sex they were having. Click on the image to download the pdf.

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Hopping hotspots

Hotspots of high species diversity are a prominent feature of modern global biodiversity patterns. Fossil and molecular evidence is starting to reveal the history of these hotspots. There have been at least three marine biodiversity hotspots during the past 50 million years. They have moved across almost half the globe, with their timing and locations coinciding with major tectonic events. The birth and death of successive hotspots highlights the link between environmental change and biodiversity patterns. The antiquity of the taxa in the modern Indo-Australian Archipelago hotspot emphasizes the role of pre-Pleistocene events in shaping modern diversity patterns. Click on the image for the pdf of the paper.

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