|dc.contributor.author||Garland, Elizabeth D.||
|dc.description||Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution February 2000||en_US||
|dc.description.abstract||Recruitment variability in benthic invertebrate populations results from variability in planktonic
larval supply and from processes occurring during and after larval settlement onto the seafloor.
The focus of this thesis is on the temporal and spatial variability in larval supply, the extent to
which planktonic larval distributions are determined by larval behaviors and physical processes,
and how differentially distributed larvae are advected to potential adult habitats by inner-shelf
circulation such as wind-driven upwelling and downwelling. This research capitalized on two
sets of larval concentration time series, collected by moored zooplankton pumps, and
complemented by synoptic hydrographic time-series data.
High variability was observed in larval concentration time series, yet the variations were nonrandom.
Within the context of the sampling regime, two dominant modes of variability existed.
One source of variation was associated with the synoptic meteorological time scale, and the other
with the diurnal time scale. Over relatively long time scales, larvae were associated with
particular water masses, defined by temperature-salinity characteristics. Within a particular water
mass, group-specific vertical patterns were observed over both long and short time scales. "Low frequency" temporal variations resulted primarily from wind-driven cross-shelf transport of water
masses in which larvae were differentially distributed relative to the thermocline. "Higher frequency"
variations were attributed to diel vertical migrations. These findings suggest that
larvae were passive to the degree that they were horizontally advected with certain water masses,
but active to the degree that they could alter their vertical position in the water column.
Local hydrodynamics, larval associations with specific water masses, and the vertical structure of
larvae resulted in differential larval transport to potential adult habitats. Larval data indicate the
times and places of possible coupling between water-column organisms and the benthos, leading
to certain predictions regarding when and where larval settlement should be greatest.
Time-series measurements of larval concentration yield a new perspective on the temporal and
spatial variability in larval distributions at an inner-shelf site. Determining how processes
operating at the synoptic and diurnal time scales are coupled, and to what extent they influence
recruitment variability, represents a challenging extension of this work.||en_US||
|dc.description.sponsorship||This research was supported by grants from the National Science Foundation's Coastal
Ocean Processes (CoOP) Program (OCE91-23514 and OCE92-21615 to Cheryl Ann
Butman, and OCE96-33025 to Steven J. Lentz and Cheryl Ann Butman); the National
Oceanic and Atmospheric Administration's National Sea Grant Program Office,
Department of Commerce (Grant # NA46RG0470, Woods Hole Oceanographic
Institution Sea Grant Project No. RB-132 and RB-139 to Cheryl Ann Butman and
Elizabeth D. Garland); and the WHOI Education Program.||en_US||
|dc.publisher||Massachusetts Institute of Technology and Woods Hole Oceanographic Institution||en_US||
|dc.title||Temporal variability and vertical structure in larval abundance : the potential roles of biological and physical processes||en_US||