Date Awarded

2012

Document Type

Thesis

Degree Name

Master of Science (M.Sc.)

Department

Virginia Institute of Marine Science

Abstract

In terrestrial systems, seed burial is widely recognized as a vital process that influences small- and large-scale plant population patterns. Despite its demonstrated importance in terrestrial literature, very little is known about seed burial in seagrasses. Zostera marina is a perennial seagrass found in northern temperate oceans worldwide, and is the dominant seagrass found in the Chesapeake Bay. In terrestrial systems, seed burial is frequently mediated by soil-dwelling invertebrates. The goal of this work was to determine the role that benthic infauna play in the burial of Z. marina seeds by addressing the following questions: 1. Are seeds on sediments containing infauna buried more quickly than sediments without infauna, and 2. Does the infaunal feeding mode (e.g. head-up vs. head-down feeder, sessile vs. errant, or deposit feeder vs. omnivore) affect seed burial? Three mesocosm studies were conducted in sediment cores (80cm2 x 11cm) collected from the Chesapeake Bay, defaunated, and populated with single specimens of infauna of different feeding modes: Amphitrite ornata (sessile head-up deposit feeder), Neanthes succinea (errant omnivore), or Clymene/la torquata (sessile head down deposit feeder), or Pectinaria gou/di (errant head down deposit feeder). Control cores had no specimen added. Ten particles (either Z. marina seeds or colored beads) were added to the surface of each core, and the depth of the particles was detennined at different time scales up to 14 days. Seeds in all animal cores were significantly more likely to be buried than seeds in control cores (p~1.03x 1 0"6 ), although burial rates varied by species. N. succinea and P. gou/di showed the most dramatic burial: ~55% of seeds buried after 3 days and seeds buried below 2.5cm and 4.0cm, respectively, after 2 weeks. N. succinea also showed evidence for actively burying seeds. A. ornata and C. torquata had 12% and 24% of seeds buried, respectively, after 3 days and both had seeds buried below l.Ocm after 2 weeks. The results of this study indicate that Z. marina seed burial is facilitated by infaunal activity, and that burial patterns are species specific. In addition, burial is rapid and occurs on a time scale of days. While abiotic processes may be initially important in seed burial, the direct (active movement of sediment), and indirect (formation of mounds and holes) consequences of biotic processes by infauna may prove to be dominant and relevant to seed escape from predation, retention in suitable settlement sites, and movement to a sediment depth suitable for germination.

DOI

https://dx.doi.org/doi:10.25773/v5-t6b8-6808

Rights

© The Author

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