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John Mohan


Ph.D. Student, Marine Science, University of Texas Marine Science Institute

M.S. Biology, East Carolina University, 2009
Thesis:  Habitat utilization of juvenile striped bass Morone saxatilis in Albemarle Sound inferred from otolith and water chemistry.

B.S. Biology, Wildlife and Fisheries Science Minor, Penn State University, 2006


Mohan, J.A., N.M. Halden, and R.A. Rulifson.  2015.  Habitat use of juvenile striped bass Morone saxatilis (Actinopterygii: Moronidae) in rivers spanning a salinity gradient across a shallow wind-driven estuary.  Environmental Biology of Fishes. 4:1105-1116.  LINK.

Mohan, J.A., and B.D. Walther. 2015. Spatiotemporal variation of trace elements and stable isotopes in subtropical estuaries: II. Regional, local, and seasonal salinity-element relationships.  Estuaries and Coasts. 38:769-781. LINK

Limburg, K.E., Walther, B.D., Lu, Z., Jackman, G., Mohan, J., Walther, Y., Nissling, A., Weber, P.K., and A.K. Schmitt. 2015.  In search of the dead zone: use of otoliths for tracking fish exposure to hypoxia.  Journal of Marine Systems141:167-178. LINK

Mohan, J., Rahman, M.S., Thomas, P., and B.D. Walther. 2014. Influence of constant and periodic experimental hypoxic stress on Atlantic croaker otolith chemistry.  Aquatic Biology. 20:1-11.  LINK

Mohan, J.A., R.A. Rulifson, D.R. Corbett, and N.M.Halden. 2012. Validation of oligohaline elemental otolith signatures of striped bass using in situ caging experiments and water chemistry.  Marine and Coastal Fisheries: Dynamics, Management, and Ecosystem Science. 4:57-70.  LINK


Otoliths, or "ear stones," are bone-like structures that make up the inner ear of teleost fish.  Otoliths grow as alternating layers of calcium carbonate and protein on daily (juvenile) and annular (adult) increments in fish.  As fish grow, dissolved elements (such as strontium, barium, and manganese) are taken up through the gills from the environment and get deposited into the crystal structure.  This provides a permanent chronological record of the environments where a fish has been, if the relationships between otolith and water chemistries are known.  My research interests include using laboratory and field studies to investigate the relationships between otoliths and the environment that can be used to answer questions related to fish ecology such as migration patterns, habitat use, and growth and also using otolith chemistry to understand past environmental conditions a fish was exposed to, such as hypoxia.  


Contact Information

The University of Texas

Marine Science Institute
750 Channel View Drive
Port Aransas, Texas 78373

Office: (361) 749-6797
(361) 749-6749