J.J. Orth homepage

Robert J. Orth

Adjunct Faculty

Retired: 2021
Section: Coastal & Ocean Processes
Email: [[jjorth]]
Website: {{, Submerged Aquatic Vegetation (SAV)}}
Phone: (804) 684-7392
Interests: Submerged aquatic vegetation biology and ecology.
Office: Andrews Hall 308

  • B.A., Rutgers University, 1969
  • M.S., University of Virginia, 1971
  • Ph.D., University of Maryland, 1975
Research Interests

My research focuses on the biology and ecology of seagrasses, principally in the Chesapeake Bay. My current emphasis is on habitat restoration and conservation and understanding the principles and processes governing the dynamics of these plant communities. One major element of our program is the annual monitoring of the distribution and abundance of submerged aquatic vegetation in the Chesapeake Bay and the seaside bays of the Maryland and Virginia barrier islands, using a combination of low-level remote sensing and GIS tools. Annual reports documenting the patterns of bay grasses are available on our SAV website and these data are being used by federal and state management agencies as one of the measurable products in assessing the success of efforts to clean up the waters of Chesapeake Bay. The second major element focuses on seed ecology issues, primarily with eelgrass, with emphasis on abiotic and biotic processes influencing seed germination and seed dispersal. A third major element is the restoration of eelgrass in the Chesapeake Bay and the seaside bays of Virginia’s barrier island lagoon system using a basic and applied research approach primarily using seeds.   The fourth and final element is a strong advisory component to the Commonwealth of Virginia and the EPA’s Chesapeake Bay Program in assuring seagrass beds are protected from direct and indirect impacts. Our research program emphasizes the dissemination of information in both technical documents, as well as scientific peer-reviewed journals.

Current Projects
  • Overcoming critical recruitment bottlenecks limiting seedling establishment in degraded seagrass ecosystems in Australia: a systems approach to restoration. Funded by the Australian Research Council (with G. Kendrick, K. Dixon, J. Statton).
  • Monitoring the distribution of SAV in the Chesapeake Bay and Coastal Bays. Funded by USEPA, VADEQ, VA CZM, MD DNR.
  • Restoration of seagrasses and bay scallops in the seaside lagoons of Virginia, Funded by VMRC’s Recreational Fishing Fund.
  • Boat scarring effects in Virginia waters. Funded by VMRC’s Recreational Fishing Fund.
Selected Publications

Lefcheck, J. S., Orth, R. J., W. C. Dennison, D. J. Wilcox, R. R. Murphy, J. Keisman, C. Gurbisz, M. Hannam, J. B. Landry, K. A. Moore, C. J. Patrick, J. Testa, D. E. Weller, R. A. Batiuk. (2018). Long-term nutrient reductions lead to the unprecedented recovery of a temperate coastal region. Proceedings of the National Academy of Sciences.

Reynolds, P, Stachowicz, J., Hovel, K., Boström, Christoffer; Boyer, K., Cusson, M., Eklöf, J., Engel, F., Engelen, A., Eriksson, B. K., Fodrie, F., Griffin, J., Hereu, C., Hori, M., Hanley, T., Ivanov, M., Jorgensen, P., Kruschel, C., Lee, K-S., McGlathery, K., Moksnes, P.-O., Nakaoka, M., Tomas Nash, F., O'Connor, M., O'Connor, N., Orth, R., Rossi, F., Ruesink, J., Sotka, E., Unsworth, R., Whalen, M., Duffy, J. 2018.  Latitude, temperature and habitat complexity predict predation pressure in eelgrass beds across the Northern Hemisphere. Ecology 99:29-35. DOI: 10.1002/ecy.2064.

Patrick, C. J., D. E. Weller, R. J. Orth, D. E. Wilcox, M. Hannam. 2018. Land use and salinity drive changes in SAV abundance and community composition. Estuaries and Coasts. doi:10.1007/s12237-017-0250-1

Statton, J., L. Ruiz-Montoya, R. J. Orth, K. W. Dixon, and G. A. Kendrick. 2017. Identifying critical recruitment bottlenecks limiting seedling establishment in a degraded seagrass ecosystem. Nature Scientific Reports. doi:1038/s41598-017-13833-y. 

Orth, R. J., W. C. Dennison, J. S. Lefcheck, C. Gurbisz, M. Hannam, J. Keisman, J. B. Landry, K. A. Moore, R. R. Murphy, C. J. Patrick, J. Testa, D. E. Weller, D. J. Wilcox. 2017. Submersed aquatic vegetation in Chesapeake Bay: sentinel species in a changing world. Bioscience 67:698-712. doi:10.1093/biosci/bix058 

Orth, R. J., J. S. Lefcheck, and D. J. Wilcox. 2017. Boat propeller scarring of seagrass beds in lower Chesapeake Bay, USA: Patterns, causes, recovery, and management. Estuaries and Coasts 40:1666-1676. doi:10.1007/s12237-017-0239-9.

Kendrick, G., R. J. Orth, J. Statton, R. Hovey, L. Ruiz Montoya, R.  Lowe, S. Krauss, and E. Sinclair. 2017. Demographic and genetic connectivity: the role and consequences of reproduction, dispersal and recruitment in seagrasses.  Biological Reviews 92:921-938. doi: 10.1111/brv.12261

Lefcheck, J. S., D. J. Wilcox, R. R. Murphy, S. R. Marion, R. J. Orth. 2017. Multiple stressors threaten a critical foundation species in Chesapeake Bay. Global Biology Change 23: 3474-3483. doi: 10.11.11/gcb.13623

Johnson, A. J., K. A. Moore, and R. J. Orth. 2017. The influence of resource availability on flowering intensity in Zostera marina (L.). Journal of Experimental Marine Biology and Ecology 490:13-22.

Oreska, M. P., B. Truitt, R. J. Orth, and M. W. Luckenbach. 2017. The bay scallop, Argopecten irradians, industry collapse in Virginia and its implications for the successful seagrass-scallop management. Marine Policy 75:116-124.

Lefcheck, J. S., S. R. Marion, and R. J. Orth. 2017. Actively restored ecosystems as a refuge for biological diversity: A case study from eelgrass (Zostera marina L.). Estuaries and Coasts 40: 200-212. doi: 10.1007/s12237-016-0141-x

Hyndes, G. A., K. L. Heck Jr., A. Vergés, E. S. Harvey, G. A. Kendrick, P. S. Lavery, K. McMahon, R. J. Orth, A. Pearce, M. Vanderklift, T. Wernberg, S. Whiting, and S. Wilson. 2016. Accelerating tropicalization and the transformation of temperate seagrass meadows. Bioscience 16:938-948. doi:10.1093/biosci/biw111. 

Govers, Laura L., Willem Man A. in ‘t Veld, Johan P. Meffert, Tjeerd J. Bouma, Patricia C. J. van Rijswick, Jannes H. T. Heusinkveld, Robert J. Orth, Marieke M. van Katwijk, Tjisse van der Heide. 2016.  Marine Phytophthora species can hamper conservation and restoration of vegetated coastal ecosystems. Royal Society Proceedings B. 283:

Lefcheck, J. S., S. R. Marion, A.V. Lombana, and R. J. Orth. 2016. Faunal communities are invariant to fragmentation in experimental seagrass landscapes. PloS ONE. 11(5): e0156550. doi:10.1371/journal.pone.0156550.

Reynolds, L. K., M. Waycott, K. J. McGlathery, R. J. Orth. 2016. Ecosystem services returned through restoration. Restoration Ecology 24:583-588. doi: 10.1111/rec.12360.

van Katwijk, M. M., A. Thorhaug, N. Marbà, R. J. Orth, C. M. Duarte, G. A. Kendrick, I. H. J.  Althuizen, E. Balestri, G. Bernard, M. L. Cambridge, A. Cunha, C. Durance, W. Giesen, Q. Han, S. Hosokawa, W. Kiswara, T. Komatsu, C. Lardicci, K. S. Lee, A. Meinesz, M. Nakaoka, K. O’Brien, E. I. Paling, C. Pickerell, A. M.A. Ransijn, and J. J. Verduin. 2016. Global review of seagrass restoration and the importance of large-scale planting. Journal of Applied Ecology 53:567-578.  DOI: 10.1111/1365-2664.12562. 

Gurbisz, C., W. M. Kemp, L. P. Sanford, and R. J. Orth. 2016. Mechanisms of storm-related loss and resilience in a large submersed plant bed. Estuaries and Coasts 39:951-966. DOI 10.1007/s12237-016-0074-4. 

Schmitt, E. L., M. W. Luckenbach, J. S. Lefcheck, and R. J. Orth. 2016. Predator-prey Interactions in a Restored Eelgrass Ecosystem: Strategies for Maximizing Success of a Reintroduced Species, Argopecten irradians. Restoration Ecology 24:558-565. doi: 10.1111/rec.12353 Supporting information at:

Abelson, A., B. S. Halpern, D. C. Reed, R. J. Orth, G. A. Kendrick, M. W. Beck, J. Belmaker, G. Krause, G. J. Edgar, L. Airoldi, E. Brokovich, R. France, N. Shashar, A. de Blaeij, N. Stambler, P. Salameh, M. Shechter and P. A. Nelson. 2016. Upgrading marine ecosystem restoration using ecological-social concepts. Bioscience 66:156-163. doi: 10.1093/biosci/biv171. 

Manley, S. R., R. J. Orth, and L. Ruiz-Montoya. 2015. The roles of dispersal and predation in determining seedling recruitment patterns in a foundational marine angiosperm. Marine Ecology Progress Series 533:109-120. doi:10.3354/meps11363.

Lefcheck, J. S., J. van Montfrans, E. Schmitt, R. J. Orth, J. E. Duffy, and M. Luckenbach. 2014. Epifaunal invertebrates as predators of juvenile bay scallop (Argopecten irradians). J. Exp. Mar. Biol. Ecol. 454:18-25.

Pre-2014 Selected Publications

Schaffler J. J, J. van Montfrans, C. M. Jones, and R. J. Orth. 2013. Fish species distribution in seagrass habitats of Chesapeake Bay are structured by abiotic and biotic factors. Marine and Coastal Fisheries 5:114-124. DOI: 10.1080/19425120.2013.804013.

Ralph, G.M., R. D. Seitz, R. J. Orth, K. E. Knick and R. N. Lipcius. 2013 Broad-scale association between seagrass cover and juvenile blue crab density in Chesapeake Bay. Marine Ecology Progress Series 488:51-63. Doi:10.3354/meps10417.

Sobocinski, K. L., R. J. Orth, M. C. Fabrizio, R. J. Latour. 2013. Historical comparison of fish community structure in Lower Chesapeake Bay seagrass habitats. Estuaries and Coasts 36:775-794. doi10.1007/s12237-013-9586-3.

Blackburn, N. J. and R. J. Orth. 2013. Seed burial in Zostera marina (eelgrass): The role of infauna. Marine Ecology Progress Series 474:135-145. doi:10.3354/meps10103.

Sumoski, S, and R. J. Orth. 2012. Biotic dispersal potential in Zostera marina (eelgrass). Marine Ecology Progress Series 471:1-10. doi:10.3354/meps10145.

Orth, R. J. and K. J. McGlathery. 2012. Eelgrass recovery in the coastal bays of the Virginia Coast Reserve, USA. Marine Ecology Progress Series 448:173-176. doi: 10.3354/meps09596

McGlathery, K. J., L. K. Reynolds, L. W. Cole, R. J. Orth, S. R. Marion, and A. Schwarzschild. 2012. Recovery trajectories during state changes from bare sediment to eelgrass dominance. Marine Ecology Progress Series 448:209-221. doi: 10.3354/meps09574.

Marion, S.R. and R.J. Orth. 2012. Seedling establishment in the eelgrass: seed burial effects on winter losses of developing seedlings. Marine Ecology Progress Series 448:197-207. doi: 10.3354/meps09612.

Orth, R. J., K. A. Moore S. R. Marion, D. J. Wilcox, and D.B. Parrish. 2012. Seed addition facilitates eelgrass recovery in a coastal bay system. Marine Ecology Progress Series 448:177-195. doi: 10.3354/meps09522

Reynolds, LK, M. Waycott, K. J. McGlathery, R. J. Orth, and J. C. Zieman. 2012. Eelgrass restoration by seed maintains genetic diversity: case study from a coastal bay system. Marine Ecology Progress Series 448:223-233. doi: 10.3354/meps09386.

Moore, K. A., E. C. Shields, D.B. Parrish, and R. J. Orth. 2012. Eelgrass survival in two contrasting systems: role of turbidity and summer water temperatures. Marine Ecology Progress Series 448:247-258. doi: 10.3354/meps09578.

Kendrick, G.A., M. Waycott, T. J. B Carruthers, M. L. Cambridge, R. Hovey, S. L. Krauss, P. S. Lavery, D. H. Les, R. J. Lowe, O. M. I Vidal, J. L. S. Ooi, R. J. Orth, D. O. Rivers, L. Ruiz-Montoya, E.A.  Sinclair, J. Statton, J. K. van Dijk, J. J Verduin. 2012. The central role of dispersal in the maintenance and persistence of seagrass populations. BioScience 62:56-65.

Short F. T., P. Polidoro, S. R. Livingstone, K. E. Carpenter, S. Bandeira, J. K. Bujang, H. Calumpong, T. Carruthers, R. Coles, W. Denniso, P. Erftmeijer, M. Fortes, A. Freeman, T. Jagtap, A. H. Kamal, G. Kendrick, J. Kenworthy, Y. La Nafie, I. Nasution, R. Orth, A. Prathep, J. Sanciengco, B. van Tussenbroek,S. Vergara, M. Waycott, J. Zieman. 2011. Extinction risk assessment of the world's seagrass species. Biological Conservation144:1961-1971.

Orth, R. J., M. R. Williams, S. R. Marion, D. J. Wilcox, T. J. B. Carruthers, K. A. Moore, W. M. Kemp, W. C. Dennison, N. Rybicki, P. Bergstrom, and R. A. Batiuk. 2010. Long term trends in submersed aquatic vegetation (SAV) in Chesapeake Bay, USA, related to water quality. Estuaries and Coasts  33:1144-1163. DOI 10.1007/s12237-010-9311-4.

Marion, S.R. and R.J. Orth. 2010. Factors influencing seedling establishment rates in eelgrass (Zostera marina) and their implications for seagrass restoration. Restoration Ecology 18:549-559.

Marion, S.R. and R.J. Orth. 2010. Innovative techniques for large scale collection, processing, storage, and dispersal of eelgrass (Zostera marina) seeds. Restoration Ecology 18:514-526.

Orth, R.J., S.R. Marion, K.A. Moore, D. J. Wilcox. 2010. Eelgrass (Zostera marina L.) in the Chesapeake Bay Region of Mid-Atlantic Coast of the USA: Challenges in Conservation and Restoration. Estuaries and Coasts 33:139-150. DOI 10.1007/s12237-009-9234-0.

Waycott, M, C. M. Duarte, T. J.B. Carruthers, R. J. Orth, W. C. Dennison, S. Olyarnik, A. Calladine, J. W. Fourqurean, K. L. Heck, Jr., A. R. Hughes, G. A. Kendrick, W. J. Kenworthy, F. T. Short, S. L. Williams. 2009. Accelerating loss of seagrasses across the globe threatens coastal ecosystems. Proceedings of the National Academy of Sciences 106:12377-12381. 10.1073/pnas.0905620106

Orth, R. J., S. R. Marion, S. Granger, and M. Traber. 2009. Evaluation of a mechanical seed planter for transplanting Zostera marina (eelgrass) seeds.  Aquatic Botany 90:204-208.

Heck, K. L., Jr.,  T. J. B. Carruthers, C. M. Duarte, R. J. Orth, A. R. Hughes, G. A. Kendrick, S. Olyarnik, M. Waycott, and S. L. Williams. 2008. Trophic transfers from seagrass meadows subsidize diverse marine and terrestrial consumers. Ecosystems 11:1198-1210.

Duarte, C. M., W. C. Dennison, R. J. Orth, and T. J. B. Carruthers. 2008. The charisma of coastal ecosystems: addressing the imbalance.  Estuaries and Coasts 31:233-238.

Wazniak, C. E., M. R. Hall, T. J. B. Carruthers, B. Sturgis, W. C. Dennison, and R. J. Orth.  2007. Linking water quality to living resources in a mid-Atlantic lagoon system, USA. Ecological Applications 17: S64-S78.

Orth, R. J. T. J.B. Carruthers, W. C. Dennison, C. M. Duarte, J. W. Fourqurean, K. L. Heck, Jr., A. R. Hughes, G. A. Kendrick, W. J. Kenworthy, S. Olyarnik, F. T. Short, M. Waycott, and S. L. Williams. 2006. A Global Crisis for Seagrass Ecosystems. Bioscience 56:987-996.

Orth, R. J., G. A. Kendrick, and S. R. Marion.  2006.  Predation on Posidonia australis seeds in seagrass habitats of Rottnest Island, Western Australia: patterns and predators. Marine Ecology Progress Series 313:105-114.

Orth, R. J., M. L. Luckenbach, S. R. Marion, K. A. Moore and D. J. Wilcox.  2006. Seagrass recovery in the Delmarva Coastal Bays, USA. Aquatic Botany 84:26-36 (doi:10.1016/j.aquatbot.2005.07.007).

Orth, R. J., M. C. Harwell, and G. J. Inglis. 2006. Ecology of seagrass seeds and dispersal strategies. pp. 111-133. In: A. W. D. Larkum, R. J. Orth, and C. M. Duarte (eds). Seagrasses: Biology, Ecology and Conservation.  Springer.  The Netherlands. 691pp.

Heck, K. H. and R. J. Orth.  2006.  Predation in seagrass beds. pp. 537-550. In: A. W. D. Larkum, R. J. Orth, and C. M. Duarte (eds). Seagrasses: Biology, Ecology and Conservation.  Springer. The Netherlands. 691 pp.

Fishman, J. R., R. J. Orth, S. Marion, and J. Bieri. 2004. A comparative test of mechanized and manual transplanting of eelgrass, Zostera marina, in Chesapeake Bay. Restoration Ecology 12:214-219.

van Montfrans, J., C. H. Ryer, and R. J. Orth. 2003. Substrate selection by blue crab, Callinectes sapidus, megalopae and first juvenile instars. Marine Ecology Progress Series 260:209-217.

Heck, K. L., Jr., C. Hays, and R. J. Orth. 2003. A Critical Evaluation of the Nursery Role Hypothesis for Seagrass Meadows. Marine Ecology Progress Series 253:123-136.

Orth, R. J., J. R. Fishman, M. C. Harwell, and S. R. Marion. 2003.  Seed density effects on germination and initial seedling establishment in eelgrass, Zostera marina, in the Chesapeake Bay region. Marine Ecology Progress Series 250:71-79.

Orth, R. J., R. A. Batiuk, P. W. Bergstrom, and K. A. Moore. 2002. A perspective on two decades of policies and regulations influencing the protection and restoration of submerged aquatic vegetation in Chesapeake Bay, USA. Bulletin of Marine Science 71:1391-1403.

Orth, R. J., K. L. Heck, Jr., and D. J.Tunbridge. 2002. Predation on seeds of the seagrass Posidonia australis in Western Australia. Marine Ecology Progress Series 244:81-88.

Harwell, M. C. and R. J. Orth. 2002. Long distance dispersal potential in a marine macrophyte.  Ecology 83:3319-3330.

Harwell, M. C. and R. J. Orth. 2002. Seed bank patterns in Chesapeake Bay eelgrass (Zostera marina L.): A baywide perspective. Estuaries 25:1196-1204.

Orth, R. J., J. R. Fishman, D. J. Wilcox, and K. A. Moore. 2002. Identification and management of fishing gear impacts in a recovering seagrass system in the coastal bays of the Delmarva Peninsula, USA. J. Coastal Research Spec. Iss. No. 37:111-129.

Orth, R. J. and J. van Montfrans. 2002. Habitat quality and prey size as determinants of postlarval and early juvenile instar blue crab survival. Marine Ecology Progress Series 231:205-213.

Parker, J. D., J. E. Duffy, and R. J. Orth. 2001.  Plant species diversity and composition: experimental effects on marine epifaunal assemblages Marine Ecology Progress Series 224:55-67.

Edgar, G., H. Mukai, and R. J. Orth. 2001. Fish and macrobenthic fauna: measurement methods for their biomass and abundance in seagrass. Pp. 255-270. In:  F.T. Short and R. G. Coles (eds). Global Seagrass Research Methods. Elsevier Science. New York.

Beck, M.W., K. L. Heck, K. Able, D. Childers, D. Eggleston, B. Gilanders, B. Halpern, C, Hays, K. Hoshino, T. Minello, R. Orth, P. Sheridan, M. Weinstein. 2001. Towards better identification, conservation, and management of estuarine and marine nurseries for fish and invertebrates. Bioscience 51:633-641.

Orth, R. J., M. C. Harwell, E. M. Bailey, A. Bartholomew, J. T. Jawad, A. V. Lombana,  K. A. Moore, J. M. Rhode, H. E. Woods. 2000. A review of issues in seagrass seed dormancy and germination:  Implications for conversation and restoration. Mar. Ecol. Prog. Ser. 200:277-288.

Orth, R. J., M. W. Luckenbach, and K. A. Moore. 1994. Seed dispersal in a marine macrophyte: Implications for colonization and restoration. Ecology, 75:1927-1939.

Dennison, W. C., R. J. Orth, K. A. Moore, J. C. Stevenson, V. Carter, S. Kollar, P. Bergstrom, and R. Batiuk. 1993. Assessing water quality with submersed aquatic vegetation. Bioscience 43:86-94.

Current Students

Andrew Johnson, Ph.D. Seed bottlenecks in seagrass species.

Past Students
  • Andrew Johnson, M.S. awarded 2015. Role of abiotic factors influencing eelgrass flowering.
  • Erika Schmitt, M.S. awarded 2015. Relative predation rates on bay scallops relating to spring and fall spawns.
  • Steve Manley, M.S. awarded 2014. The roles of dispersal and predation in determining the spatial ecology of an eelgrass system.
  • Sarah Sumoski, M.S. awarded 2012. Mobile animals as a potential dispersal mechanism in Zostera marina (eelgrass).
  • Natalia Blackburn, M.S. awarded 2012. Seed burial in Zostera marina (eelgrass): the role of infauna.
  • Scott Marion, M.S. awarded 2002. Effects of habitat fragmentation on the utilization of eelgrass habitat by mobile epifauna and macrofauna.
  • Helen Woods, M.S. awarded 2001. An examination of potential conflicts between SAV and hard clam aquaculture in the lower Chesapeake Bay (co-major professor with C. Hershner).
  • Matt Harwell, Ph.D. awarded 2000. Spatial analysis of ecological dispersal mechanisms and patch dynamics of SAV in Chesapeake Bay.
  • Al Lombana, M.S. awarded 1999.
  • John Parker, M.S. awarded 1998.
Courses Taught
  • MS 656:  Seagrass Ecosystems
Professional Memberships
  • Estuarine Research Federation (ERF)