Selected current research
I. NASA New Investigator Program - Improving estimates of primary productivity for the open ocean (grant # NNX10AQ81G)
Suspended in the surface waters of our oceans, phytoplankton transform energy and elements and are responsible for roughly half of the net photosynthetic carbon fixation on planet Earth. In the vast regions of the ocean characterized by low standing stocks of photosynthetic biomass and available nutrients, exisiting algorithms for net primary production have large uncertainties that have primarily been attributed to inadequacies in model descriptions of physiological variability. To improve upon the present state of satellite-based algorithms for marine productivity, we have begun a reanalysis of existing time-series data collected by the Hawaii Ocean Time series program to assess potential relationships between productivity parameterizations and community structure derived from discrete pigment analyses, absorbance spectra and particle size distributions. These data mining exercises will be complemented by laboratory and field experiments designed to compare high resolution in situ measurements of size and hyperspectral absorption with results of discrete pigment-based analysis and models of community size structure.
II. NSF OCE-Production and decomposition of particulate and dissolved organic matter
At the ecosystem scale, the balance of productivity and respiration in the ocean is regulated by the availability of potentially limiting nutrients such as nitrogen (N) and phosphorus (P). Therefore, understanding the coupling of carbon (C), N, and P cycles is central to the determination of the long-term controls of the magnitude and variability of primary production and export. Nonetheless, a paucity of simultaneous measures of dissolved organic C, N and P (DOC, DON, DOP), and a relative lack of information on production and decomposition processes have hindered progress in understanding the coupled dynamics of these pools. Recent studies of dissolved organic matter dynamics show large departures from Redfield trajectories driven by alterations in phytoplankton species composition, the stoichiometry and chemical composition of organic matter production, differential lability of organic compounds and preferential remineralization of N and P by heterotrophic bacteria. One active area of my research program has sought to characterize the composition, lability and remineralization stoichiometry of organic P-C-N produced by ecologically significant photosynthetic genera. To accomplish this goal, in collaboration with Adina Paytan (UCSC), we have designed a series of in situ and laboratory-based bio-assays where particulate (POM) and DOM isolated from Prochlorococcus, phosphonate-containing strains of Trichodesmium and natural populations are added to resident microbial populations and incubated in the laboratory and at sea. This work aims to estimate the labile and semi-labile fraction of organic material generated by ecologically significant genera and determine the microbially-mediated remineralization stoichiometry (P-C-N) and biomolecular alterations that occur with POM decomposition. This work will naturally extend to numerical characterizations of elemental turnover in the ocean.
III. NOAA- Monitoring Oregon's Coastal Harmful Algae (MOCHA): Integrated HAB monitoring and event response for coastal Oregon Center
Phycotoxins such as saxitoxin and domoic acid have had a significant impact on Oregon coastal communities and their economy for decades. In recent years, particularly 2003, 2005, and 2010, domoic acid and saxitoxin contamination has resulted in spatially large and prolonged closures of razor clam and mussel beds to harvesting. In the only economic assessment made to date for the region, the Oregon Department of Fish and Wildlife (ODFW) estimated that the cost of a domoic acid-related closure of the razor clam fishery at Clatsop Beach in 2003 alone cost the local communities $4.8 million. At present, closure of shellfish beds in Oregon is based on monthly or bi-weekly sampling of sentinel invertebrate species for the presence of toxins. MERHAB funding of MOCHA has allowed development of a comprehensive event response plan to help minimize the impact of HAB events on coastal communities. This project is designed to provide the scientific data needed to understand the ecological mechanisms underlying the occurrence of HABs in Oregon. By partnering researchers from state universities and NOAA with representatives of agencies responsible for the state’s monitoring programs we have been able to develop an ecosystem-based approach to HAB monitoring and event response in Oregon. While extensive research has been conducted on the causes and patterns of HAB events in California and Washington, the Oregon coast has generally been ignored even though it represents a key transition zone in west coast oceanography with significant gradients in upwelling and ecosystem response. This project plays a key role in filling that gap while improving Oregon’s capacity for HAB monitoring and event response.
IV. The North Pacific Plastic Patch: Research led by the Center for Microbial Research and Education (C-MORE)
(navigate the below slideshow to see images from the North Pacific Plastic Patch)
There are a few supposed facts about plastic in the ocean that you might have heard: (1) There is a massive swirling gyre of plastic, the “Great Pacific Garbage Patch,” between California and Japan that is twice the size of Texas; and (2) this plastic debris outweighs plankton and is growing in size with each passing year. Interestingly, the scientific literature does not support these statements.
In 2008, I participated in one of the few scientific expeditions aimed at characterizing the abundance of plastic debris and the associated impact of plastic on microbial communities. That expedition was part of research funded by the National Science Foundation through C-MORE, the Center for Microbial Oceanography: Research and Education.
Standing on the bow of a research ship, floating in the heart of the “Great Pacific Garbage Patch,” my colleagues and I looked out onto a calm, apparently pristine blue ocean. By towing a mesh net through these waters and deploying instruments capable of measuring particle size and abundance, it became apparent that the sea around us actually contained a dilute soup of very small pieces of plastic that were largely invisible to the naked eye. Below I've added an image of some of this plastic that was collected by a colleague (Charlie Miller) in 1971 in teh North Pacific. We're still finding pieces like this on our coasts and in our oceans today. To put the recorded concentrations of plastic into perspective, if you were to line up 1,000 1-liter Nalgene™ bottles filled with ocean water from this location, between one and five of them would contain a single piece of plastic roughly the size of a worn down pencil eraser. If we compare the amount of plastic to the amount of plankton (millions to billions of organisms per milliliter), plankton outnumber and outweigh plastic by a considerable measure.
The amount of plastic out there isn’t inconsequential, but using the highest concentrations ever reported by scientists, the plastic debris floating in the surface waters of the North Pacific could be corralled to produce a solid patch that is a small fraction of the state of Texas, not twice the size. This is not to say that the issue of plastic in the ocean should be dismissed, rather the problem is more complex and enigmatic than that conveyed by the imagery of a cohesive patch spread out over a few remote locations.
A number of state, federal and non-profit funded research projects have documented extensive plastic pollution in our oceans. This work has revealed that plastic is not confined to the subtropical gyres: It appears to be more widespread but still rather dilute. The most extensive research into the scale of plastic pollution in the ocean has been led by scientists at the Sea Education Association program and the Woods Hole Oceanographic Institution. These researchers compiled a 22-year survey of plastic in the western North Atlantic. They reported concentrations of plastic very similar to what we have found in the Pacific Ocean, but there is a catch. The amount of plastic in the North Atlantic has not increased since the mid-1980s, despite a surge in plastic production over the same period. This unexpected conclusion has led to a lot of speculation: Are we doing a better job of preventing plastics from getting into the ocean? Is more plastic sinking out of the surface waters? Is plastic being more efficiently broken down? At present, we just don’t know the answers.
New research findings by several research groups may point to one way to unravel this mystery: microbes! In both our own research and in the Atlantic, it’s been observed that certain microbes actually live attached to plastic flotsam. Not only is plastic prime real estate for these microbes, but they may actively degrade plastic in the ocean. This is an interesting finding that may partially explain the mystery of ‘missing plastic’ in the Atlantic.
An additional consequence of the widespread image of ‘plastic patches’ or ‘plastic islands’ is that it seems we should be able to remove it from the ocean. If it were indeed a patch, perhaps that would be feasible, but given that it’s more like a very dilute soup, such efforts would be costly, inefficient and may have unforeseen consequences. It would be difficult, for example, to corral and remove plastic particles from ocean waters without inadvertently removing phytoplankton, zooplankton and small surface-dwelling aquatic creatures. These small organisms are the heartbeat of the ocean. They are the foundation of healthy ocean food chains and immensely more abundant than plastic debris.
The more practical answer is to reduce the input of plastic into our oceans in the first place. There are a few other reasons for doing this: (1) It is well known that plastic debris can adsorb toxins such as PCBs; and (2) whether toxic or not, fish and seabirds (notably albatross) may ingest this plastic and potentially face starvation as a result. Animal entanglement by derelict fishing gear, monofilament line and other large plastic is another consequence of plastic debris..
So while the images of Texas-sized islands of plastic is more science-fiction than truth, the more insidious problem of a soup of plastic that we may never be able to clean up and which could impact ocean food chains deserves continued research and attention.
If there is a take home message for me it's that plastic clearly does not belong in the ocean, but there is no need to exaggerate the problem to Texas-sized proportions to make that point.
Suspended in the surface waters of our oceans, phytoplankton transform energy and elements and are responsible for roughly half of the net photosynthetic carbon fixation on planet Earth. In the vast regions of the ocean characterized by low standing stocks of photosynthetic biomass and available nutrients, exisiting algorithms for net primary production have large uncertainties that have primarily been attributed to inadequacies in model descriptions of physiological variability. To improve upon the present state of satellite-based algorithms for marine productivity, we have begun a reanalysis of existing time-series data collected by the Hawaii Ocean Time series program to assess potential relationships between productivity parameterizations and community structure derived from discrete pigment analyses, absorbance spectra and particle size distributions. These data mining exercises will be complemented by laboratory and field experiments designed to compare high resolution in situ measurements of size and hyperspectral absorption with results of discrete pigment-based analysis and models of community size structure.
II. NSF OCE-Production and decomposition of particulate and dissolved organic matter
At the ecosystem scale, the balance of productivity and respiration in the ocean is regulated by the availability of potentially limiting nutrients such as nitrogen (N) and phosphorus (P). Therefore, understanding the coupling of carbon (C), N, and P cycles is central to the determination of the long-term controls of the magnitude and variability of primary production and export. Nonetheless, a paucity of simultaneous measures of dissolved organic C, N and P (DOC, DON, DOP), and a relative lack of information on production and decomposition processes have hindered progress in understanding the coupled dynamics of these pools. Recent studies of dissolved organic matter dynamics show large departures from Redfield trajectories driven by alterations in phytoplankton species composition, the stoichiometry and chemical composition of organic matter production, differential lability of organic compounds and preferential remineralization of N and P by heterotrophic bacteria. One active area of my research program has sought to characterize the composition, lability and remineralization stoichiometry of organic P-C-N produced by ecologically significant photosynthetic genera. To accomplish this goal, in collaboration with Adina Paytan (UCSC), we have designed a series of in situ and laboratory-based bio-assays where particulate (POM) and DOM isolated from Prochlorococcus, phosphonate-containing strains of Trichodesmium and natural populations are added to resident microbial populations and incubated in the laboratory and at sea. This work aims to estimate the labile and semi-labile fraction of organic material generated by ecologically significant genera and determine the microbially-mediated remineralization stoichiometry (P-C-N) and biomolecular alterations that occur with POM decomposition. This work will naturally extend to numerical characterizations of elemental turnover in the ocean.
III. NOAA- Monitoring Oregon's Coastal Harmful Algae (MOCHA): Integrated HAB monitoring and event response for coastal Oregon Center
Phycotoxins such as saxitoxin and domoic acid have had a significant impact on Oregon coastal communities and their economy for decades. In recent years, particularly 2003, 2005, and 2010, domoic acid and saxitoxin contamination has resulted in spatially large and prolonged closures of razor clam and mussel beds to harvesting. In the only economic assessment made to date for the region, the Oregon Department of Fish and Wildlife (ODFW) estimated that the cost of a domoic acid-related closure of the razor clam fishery at Clatsop Beach in 2003 alone cost the local communities $4.8 million. At present, closure of shellfish beds in Oregon is based on monthly or bi-weekly sampling of sentinel invertebrate species for the presence of toxins. MERHAB funding of MOCHA has allowed development of a comprehensive event response plan to help minimize the impact of HAB events on coastal communities. This project is designed to provide the scientific data needed to understand the ecological mechanisms underlying the occurrence of HABs in Oregon. By partnering researchers from state universities and NOAA with representatives of agencies responsible for the state’s monitoring programs we have been able to develop an ecosystem-based approach to HAB monitoring and event response in Oregon. While extensive research has been conducted on the causes and patterns of HAB events in California and Washington, the Oregon coast has generally been ignored even though it represents a key transition zone in west coast oceanography with significant gradients in upwelling and ecosystem response. This project plays a key role in filling that gap while improving Oregon’s capacity for HAB monitoring and event response.
IV. The North Pacific Plastic Patch: Research led by the Center for Microbial Research and Education (C-MORE)
(navigate the below slideshow to see images from the North Pacific Plastic Patch)
There are a few supposed facts about plastic in the ocean that you might have heard: (1) There is a massive swirling gyre of plastic, the “Great Pacific Garbage Patch,” between California and Japan that is twice the size of Texas; and (2) this plastic debris outweighs plankton and is growing in size with each passing year. Interestingly, the scientific literature does not support these statements.
In 2008, I participated in one of the few scientific expeditions aimed at characterizing the abundance of plastic debris and the associated impact of plastic on microbial communities. That expedition was part of research funded by the National Science Foundation through C-MORE, the Center for Microbial Oceanography: Research and Education.
Standing on the bow of a research ship, floating in the heart of the “Great Pacific Garbage Patch,” my colleagues and I looked out onto a calm, apparently pristine blue ocean. By towing a mesh net through these waters and deploying instruments capable of measuring particle size and abundance, it became apparent that the sea around us actually contained a dilute soup of very small pieces of plastic that were largely invisible to the naked eye. Below I've added an image of some of this plastic that was collected by a colleague (Charlie Miller) in 1971 in teh North Pacific. We're still finding pieces like this on our coasts and in our oceans today. To put the recorded concentrations of plastic into perspective, if you were to line up 1,000 1-liter Nalgene™ bottles filled with ocean water from this location, between one and five of them would contain a single piece of plastic roughly the size of a worn down pencil eraser. If we compare the amount of plastic to the amount of plankton (millions to billions of organisms per milliliter), plankton outnumber and outweigh plastic by a considerable measure.
The amount of plastic out there isn’t inconsequential, but using the highest concentrations ever reported by scientists, the plastic debris floating in the surface waters of the North Pacific could be corralled to produce a solid patch that is a small fraction of the state of Texas, not twice the size. This is not to say that the issue of plastic in the ocean should be dismissed, rather the problem is more complex and enigmatic than that conveyed by the imagery of a cohesive patch spread out over a few remote locations.
A number of state, federal and non-profit funded research projects have documented extensive plastic pollution in our oceans. This work has revealed that plastic is not confined to the subtropical gyres: It appears to be more widespread but still rather dilute. The most extensive research into the scale of plastic pollution in the ocean has been led by scientists at the Sea Education Association program and the Woods Hole Oceanographic Institution. These researchers compiled a 22-year survey of plastic in the western North Atlantic. They reported concentrations of plastic very similar to what we have found in the Pacific Ocean, but there is a catch. The amount of plastic in the North Atlantic has not increased since the mid-1980s, despite a surge in plastic production over the same period. This unexpected conclusion has led to a lot of speculation: Are we doing a better job of preventing plastics from getting into the ocean? Is more plastic sinking out of the surface waters? Is plastic being more efficiently broken down? At present, we just don’t know the answers.
New research findings by several research groups may point to one way to unravel this mystery: microbes! In both our own research and in the Atlantic, it’s been observed that certain microbes actually live attached to plastic flotsam. Not only is plastic prime real estate for these microbes, but they may actively degrade plastic in the ocean. This is an interesting finding that may partially explain the mystery of ‘missing plastic’ in the Atlantic.
An additional consequence of the widespread image of ‘plastic patches’ or ‘plastic islands’ is that it seems we should be able to remove it from the ocean. If it were indeed a patch, perhaps that would be feasible, but given that it’s more like a very dilute soup, such efforts would be costly, inefficient and may have unforeseen consequences. It would be difficult, for example, to corral and remove plastic particles from ocean waters without inadvertently removing phytoplankton, zooplankton and small surface-dwelling aquatic creatures. These small organisms are the heartbeat of the ocean. They are the foundation of healthy ocean food chains and immensely more abundant than plastic debris.
The more practical answer is to reduce the input of plastic into our oceans in the first place. There are a few other reasons for doing this: (1) It is well known that plastic debris can adsorb toxins such as PCBs; and (2) whether toxic or not, fish and seabirds (notably albatross) may ingest this plastic and potentially face starvation as a result. Animal entanglement by derelict fishing gear, monofilament line and other large plastic is another consequence of plastic debris..
So while the images of Texas-sized islands of plastic is more science-fiction than truth, the more insidious problem of a soup of plastic that we may never be able to clean up and which could impact ocean food chains deserves continued research and attention.
If there is a take home message for me it's that plastic clearly does not belong in the ocean, but there is no need to exaggerate the problem to Texas-sized proportions to make that point.