Ocean Modeling & Bio-physical Processes

 

Laurent Chérubin, Ph.D.
Associate Research Professor
772-242-2314
lcherubin@fau.edu
 

Research overview

Dr. Chérubin is a physical oceanographer specialized in the understanding of ocean dynamics, which is the study of why the water moves the way it moves. It establishes the connection between forces that act on the ocean, such as the wind, the moon and the heat from the sun, and the water motions. His research has focused on dynamics of motions associated with instabilities in coastal currents as well as mesoscale and sub-mesoscale eddies. Dr. Chérubin has used both theoretical analytical and numerical models in the quasi-geostrophic and shallow-water formalisms to study the linear and weekly nonlinear instability properties of currents such as the Mediterranean Undercurrents in the Gulf of Cadiz, the Loop Current in the Gulf of Mexcico and the Florida Current in the Florida Strait. He also applied the same methods to study the dynamics of eddies generated by current instabilities, such as the Mediterranean Water eddies (Meddies), the Loop Current rings and various smaller eddies associated with topographically induced perturbation on transverse currents in places like the Meso-American Region, the Florida Keys and the US Virgin Islands. Dr. Chérubin has also used a hierarchy of numerical models of increasing complexity such as contour surgery CASL model (Chérubin et al., 2007), MICOM (Chérubin et al., 2006) and ROMS (Baums et al., 2006; Cherubin & Richardson, 2007; Cherubin et al., 2008; Cherubin et al., 2011; Criales et al., in prep) to apprehend the nonlinear features associated with the development of dynamical instabilities.

Those nonlinear features are, in the real ocean, the location of very productive ecosystems that concentrate food supply and top predators at all levels of the food chain, but also all levels of development (i.e., eggs to larvae to adults). In the coastal ocean, particularly in reef ecosystems, coral reef platforms are often found at the edge of island shelves, the frontier to the deep ocean, such as in the US Virgin Islands. Another example is the reef track of the Florida Keys, which lies at the frontier between the shelf and Florida Current waters. This frontier is populated by a variety of eddies that are used in many ways by both reef and pelagic marine organisms. Reef fish and pelagic predators use them for several purposes, including (1) to find food, because eddies and their filaments’ internal dynamics contribute to concentrate nutrients, which promote plankton development and the presence of bait fish, and (2) as spawning grounds; large predators, such as groupers, snappers, jack, but also sailfish and other large fish use them to ensure a food-rich environment for offspring. More importantly, this environment will last in time and space as long as eddies and their surrounding filament(s) will maintain their coherence and will not cease to exist.

Reefs and their fish populations provide food for local inhabitants, are a key factor in the global marine ecosystem and provide positive economic impacts through tourism. For example, 116 million people live within 100 km of Caribbean coastlines, and many livelihoods depend strongly on the marine environment. Despite their value, coral reefs in the world are under threat. Growing coastal populations and rising tourist numbers exert increasing pressure. But knowledge fundamental to assessing the survivability of reefs and reef-spawning fishes is lacking, as is the basis of understanding how these ecosystems will become modified in a changing climate.

Therefore Dr. Chérubin's research focuses essentially on understanding the dynamics of coastal oceanic features through the lens of reproduction strategies and food availability in coastal ecosystems for larvae originating from spawning aggregations. He also is interested in the mechanisms of larval transport and the interplay between water motions and larval behavior in order to remain in a food-rich environment away from reef predators or to be transported to a suitable recruitment habitat. This interplay also controls the spatial and temporal structure of the plankton distribution, which remains poorly studied, especially in the coastal tropical environment. Last but not least, we are usually unable to observe and to track microscopic organisms in the ocean because we lack the technology. This constitutes a critical gap in our understanding of the ocean. Often we have to estimate larval behavior and journey in order to connect the dots between their different life stages from egg to adult. Being able to observe them in their environment at any development stage is key to understanding the cause of mortality , for instance, but essential to knowing whether enough offspring survived to sustain the adult fish population or enough adults are alive to produce enough eggs to sustain the population. Mortality results from many factors such as predation, food scarcity, change in current patterns and overfishing. Thus part of Dr. Chérubin's research is dedicated to the application of novel underwater vision technology in order to improve our knowledge during this critical development stage “invisible to our eyes.”

By means of several projects, Dr. Chérubin has contributed to the establishment of a well-recognized leadership at the Rosenstiel School of Marine and Atmospheric Science in the study of connectivity applied to the Intra-America Seas (Caribbean, Bahamas, Gulf of Mexico). Most studies have been conducted by coupling high-resolution ocean models such as the Regional Oceanic Modeling System (ROMS) and individual based models (IBM) not only for coral (Baums et al., 2006), reef fishes (Paris et al., 2007; Chérubin & Paris, 2010; Chérubin et al., 2010) and shrimps (Criales et al., in prep), but also for nutrients and river run-off (Chérubin et al., 2008; Paris & Chérubin, 2008).

 

Recent projects

Marine Management Area Science - Conservation International, Modeling Larval Dispersal at Spawning Aggregation Sites, $41,402: 04/01/09 – 03/31/10. (PIs: L.M. Chérubin, C.B. Paris).

NSF-EPSCoR incubator grant, Fish movement during spawning aggregation using acoustic imagery in poor light conditions $25,000: 01/01/10-11/30/2011 (PIs: L.M. Chérubin, C.B. Paris).

NOAA CRCP, Vieques Sound and Virgin Passage Transport Study Modeling Component, $25,925: 10/01/2010-09/30/2015. (PI: L.M. Chérubin).

NSF-EPSCoR incubator grant, Connectivity of scleratinian coral larvae between mesophotic and shallow reefs, $15,000: 01/01/10-11/30/2011 (PI: A. Baker; co PIs: L.M. Chérubin, C.B. Paris).

NSF-EPSCoR Visiting Scientist fellowship, $90,263: 01/01/2011- 12/31/2011.

NOAA COCA, Integrated Models for Evaluating Climate Change, Population Growth, & Water Management (I.E. CERP) Effects on South Florida Coastal Marine and Estuarine Ecosystems (Imodec) $299,920: 08/01/12-07/31/14 (PIs: M. Criales and L.M. Chérubin).

 

References

Baums, I., C.B. Paris, L.M. Chérubin, 2006. A bio-oceanographic filter to larval dispersal in a reef building coral. Limnol & Oceanogr., 51 (5), 1960-1989

Chérubin, L.M., R.S. Nemeth, N. Idrisi, 2010. Flow and transport characteristics from a spawning aggregation site in St. Thomas (US Virgin Islands). Submitted to Ecological Modelling

Chérubin, L.M., C. Kuchinke, and C.B. Paris, 2008. Ocean circulation and terrestrial runoff dynamics in the Mesoamerican region from spectral optimization of SeaWiFS data and a high resolution simulation. Coral Reefs, 27, 503-519. DOI: 10.1007/s00338-007-0348-1

Chérubin L.M., D.G. Dritschel and X. Carton, 2007. Baroclinic instability of boundary currents over a bottom slope in a quasigeostrophic model.  J. Phys. Oceanogr., (6)37, 1661-1677

Chérubin L.M. and P. Richardson, 2007. Caribbean current variability and the influence of the Amazon and Orinoco fresh water plumes. Deep-Sea Res. I, 54, 1451-1473

Chérubin, L. M., Y. Morel, and E. P. Chassignet, 2006. Loop Current Ring shedding: formation of cyclones and interaction with topography. J. Phys. Oceanogr. 36, 569-591

Chérubin, L.M., and C.B. Paris, in prep. Consistent recruitment patterns driven by island-mass  effect. To be submitted to Ecological Modelling

Criales, M. L.M. Cherubin and J. A. Browder. Tidal stream transport of Pink shrimp larvae in  Florida Bay. To be submitted to PNAS

Paris, CB, and Chérubin LM, 2008. River-reef connectivity in the Meso-American region. Coral Reefs, 27, 773-781

Paris, C.B., L.M. Chérubin, and R.K. Cowen, 2007. Surfing, spinning, or diving from reef to reef: how does it change population connectivity? Mar. Ecol. Prog. Ser., 347, 285-300

Last Modified 1/31/14