The undersea world of Jon Witman and students

Our lab is conducting research focused around three themes: 1) physical forcing of marine benthic ecosystems 2) studies on the origin vs. the maintenance of pattern and 3) marine biodiversity. How community structuring processes vary with scale is a consideration that pervades all aspects of our research.

Populations of benthic communities are dependent on moving water for larval dispersal and in the case of sessile suspension feeders, for the supply of food. Moreover, the extent to which local populations and communities are coupled or de-coupled to common processes on large spatial scales is determined by events in the overlying water column. Our studies in physical forcing of marine ecosystems are largely considering the effects of flow and climatic variables on benthic dynamics. Ongoing investigations are concerned with the influence of stratified water columns on larval recruitment and food supply to suspension feeding communities in the US and New Zealand. In the Gulf of Maine, we've identified internal waves as a major physical forcing agent downwelling the thermocline and plankton maximum layers onto subtidal ledges causing rapid changes in environmental conditions, food and larval supply rivaling the magnitude of environmental fluctuations in the intertidal zone. More locally, we are using acoustic flow measurement technology to investigate how foraging by different guilds of shallow subtidal predators is limited by high flow regimes.

In tracking decadal-scale fluctuations in sessile invertebrate communities, I've been impressed by how many conspicuous patterns of community structure are shaped by rare events such as large disturbances, rapid changes in consumer abundance or episodic recruitment. Since these rare, but important events often occur outside of the time frame of manipulative experiments, I've combined long-term monitoring with manipulation in order to discriminate between the processes that create (originate) large scale patterns vs. those that maintain the patterns over the short term, as identified by manipulation. This approach has recently documented an unusual, massive subtidal recruitment of blue mussels on ledges spanning 100 km in the southern Gulf of Maine that apparently represents a once-in-20 yr. phenomenon. We are currently studying the ecological effects of this large-scale recruitment phenomenon.

Finally, our research in marine biodiversity is attempting to discern how important regional processes are in controlling the local species richness of epifaunal invertebrate communities. Using nearly two-dimensional rock walls as the target habitat, we are comparing local richness to regional species pools across many biogeographic regions.

Recent Postdocs in the Witman Lab

Jose Miguel Farina R.      Douglas McNaught

Recent Graduate Students in the Witman Lab:

Andrew Altieri
B.A. University of California - Santa Cruz (Marine Biology), 1999.
Influence of oceanographic features on population and community ecology in marine systems.

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