Dennis M. Allen
My connection to coastal ecosystems stems from my childhood wanderings around salt marshes and fishing with my grandfather in southern New Jersey. As a Biology major at land-locked Hobart College in upstate New York, I learned about lakes, then got a chance to return to salt marshes when I started my graduate career at Lehigh University. After completing required coursework on another land-locked campus, I had the good fortune to spend the rest of my graduate years pursuing a Ph.D. degree at the Wetlands Institute, Stone Harbor, NJ, where Lehigh University was operating the research program. Dr. Sidney Herman, who had done pioneering work with mysids and other zooplankton elsewhere on the east coast inspired me to study the ecology and behavior of mysids and other motile epibenthic fauna in local waterways. Resident postdoctoral researcher and fellow angler Bill Johnson became a senior colleague and member of my graduate committee. After finishing my degree in 1978, I moved to South Carolina to assume administrative and research responsibilities at the fledgling Baruch Marine Field Laboratory of the University of South Carolina, Georgetown. Somehow I have remained there as both a director and research professor, largely working on zooplankton dynamics and the use of shallow-water habitat by early life stages of nekton (fishes, shrimps, and crabs).
With a shared a common interest in zooplankton research and education, Bill and I decided to take on the challenge of composing a guide to the identification and ecology of the smallest animals in estuarine and coastal ocean waters. The first edition of Zooplankton of the Atlantic and Gulf Coasts (2005) took years to develop from the widely scattered, mostly old and obscure literature and our personal familiarities with the fauna. Our outstanding biological illustrator, Marni Fylling, portrayed each of the more than 340 taxa and life stages that we selected to treat in the original then second edition (2012).
Although most of my recent research has focused on juvenile nekton and their movements, fidelity, and contributions to intertidal habitats, my recent plankton-related research interests include questions about the ecology, life histories, and behavior of early life stages of shrimps, crabs, and fishes. Here are some specific studies.
1. Long-term dynamics of zooplankton in a high salinity estuary. I started making regular collections of both small (< 2 mm copepods and small invertebrate larvae susceptible to capture in a 153 micron net) and large (2-20 mm soft-bodied inverts, crustaceans, and larval fish, shrimps, and crabs susceptible to capture in a 365 micron net) mesozooplankton in 1981 and have, with lots of assistance, maintained a series of biweekly collections that continues today. The 34 year record of abundance and taxonomic composition combined with measurements of environmental conditions has indicated long-term changes that we attribute to changing climate. Warming temperatures have altered the timing of reproduction of some but not all resident and ocean-spawning species which could result in imbalances and the destabilization of food web structure.
2. Feeding ecology and growth of larval gobies and blennies. With Dr. Juli Harding (Coastal Carolina University) and students, I have been studying these small, abundant and cryptic fishes which target planktonic stages of mollusks, especially oysters. Laboratory experiments on prey preferences and diet analyses of field collected larval fishes indicate shifts in their diets with age and changes in grow rates as a function of temperature.
3. Tidal, diel, and seasonal patterns of larval crabs and shrimps in the estuary. Students from the University of SC and Coastal Carolina Univ. are working with me on larval crab and shrimp ecology. One of the largest crustacean larvae in local samples is the zoea of the green porcelain crab, Petrolisthes armatus, which expanded its geographic range northward into South Carolina about 20 years ago. Zooplankton collections are revealing the timing of larval release (from local adults) and whether the larvae are retained within the estuary or move to the coastal ocean to complete development. Laboratory culture and feeding behavior experiments are conducted on this crab and postlarval penaeid shrimps to learn more about their lives as temporary members of the zooplankton.
4. Capture and retention efficiency of larval fishes and shrimps in plankton nets of different design and net mesh size. Comparisons of numbers and sizes of larvae in towed nets and sleds of the same mesh size are used at various levels in the water column to determine the vertical distribution of larval stages at different times of the day and night. Simultaneous collections with a range of mesh sizes provides an understanding of the full range of sizes for any one species, and it also provides insights into what size groups within those length ranges are retained (or squeezed through) meshes of various sizes. This kind of information is essential to the interpretation of previously reported density data and for the design of future projects that target certain species or stages of development.
Selected zooplankton- larval fish publications:
Harding, J., D.M. Allen, S. Dingley, R.M. Tremont, S.M. Krug, and C.T. Armstrong. 2015 (in press) Ontogenetic changes in predator-prey interactions between two species of larval fishes and oyster veligers. J. Exp. Mar. Biol. Ecol.
Johnson, W.S. and D.M. Allen. 2012. Zooplankton of the Atlantic and Gulf coasts: a guide to their identification and ecology. Second edition. Johns Hopkins University Press. Baltimore. 452 pp. ISBN-13: 978-1-4214-0618-3.
Able, K.W., D.M. Allen, G. Bath-Martin, J.A. Hare, D.E. Hoss, K.E. Maranicik, P.M. Powles, D.E. Richardson, J.C. Taylor, H.J. Walsh, S.M. Warlen, and C. Wenner. 2011. Life history and habitat use of the speckled worm eel, Myrophis punctatus, along the east coast of the United States. Environmental Biology of Fishes 92(2):237-259.
Allen, D.M., V. Ogburn-Matthews, T. Buck, and E.M. Smith. 2008. Mesozooplankton responses to climate change and variability in a southeastern U.S. Estuary (1981-2003). J. of Coastal Research 55:95-110.
Allen, D.M., D. Edwards, R.F. Feller, S.E. Hutchinson, and V. Ogburn-Matthews. 1997 Detection and analysis of unusual events in long-term zooplankton and nekton data sets from North Inlet Estuary, SC, USA. Oceanol. Acta. 20(1):165-175.
Houser, D.S. and D.M. Allen. Zooplankton dynamics in an intertidal salt marsh basin. 1996. Estuaries. 19(3):659-673.
Allen, D.M., W.S. Johnson, and V. Ogburn-Matthews. 1995. Trophic relationships and seasonal utilization of salt-marsh creeks by zooplanktivorous fishes. Env. Biol. Fishes. 42:37-50.
Johnson, W.S., D.M. Allen, M.V. Ogburn, and S.E. Stancyk. 1990. Short-term predation responses of bay anchovies, Anchoa mitchilli, to zooplankton prey availability. Mar. Ecol. Prog. Ser. 64:55-68.
Allen, D.M. 1984. Population dynamics of the mysid shrimp Mysidopsis bigelowi W.M. Tattersall in a temperate estuary. J. Crus. Biol. 4(1):25-34.
Allen, D.M. 1982. Autecology of the cryptic mysid crustacean, Heteromysis formosa S.I. Smith 1873, in a temperate estuary. Hydrobiologia. 93:1-7.
Allen, D.M. and W.B. Allen. 1981. Seasonal dynamics of a leech-mysid shrimp interaction in a temperate salt marsh. Biol. Bull. 160:1-10.