Skip to main content

Free Content The influence of seagrass cover on population structure and individual growth rate of a suspension-feeding bivalve, Mercenaria mercenaria

Download Article:
(PDF 855.1 kb)
The average density of Mercenaria mercenaria in 216 ¼-m2 samples taken in spring 1980 from an eelgrass (Zostera marina) bed in Back Sound, North Carolina, was 9.0 m–2, more than five times the average density (1.6 m–2) in 216 ¼-m2 samples from a nearby sand flat. Size-frequency distributions differed between environments, with the sand flat containing a larger fraction of its Mercenaria in the smallest size class (0–1 cm). Use of internal growth lines to age all Mercenaria collected revealed that age-frequency distributions also differed between environments but that average Mercenaria age was identical in the two collections. The average sizes of 0-, 1-, and 2-year-class Mercenaria were significantly greater in the seagrass collection. Furthermore, the logarithmic growth curve fit through the mean sizes of each year class for the seagrass collection fell significantly above the analogous sand-flat curve for all ages, implying higher growth rates inside the seagrass environment.

The seagrass environment contained a higher proportion of finer sediments, more silts and clays, and higher organic content both in surface (0–2 cm) and-in deep (0–20 cm) cores. Current velocities measured by dye release in the field demonstrated a substantial baffling effect by the seagrass, with average surface velocities above the blades about 3–5 × average velocities at depths within the seagrass canopy. This baffling by seagrass reduced currents near the bottom, where Mercenaria feeds, to levels 50% lower than those measured simultaneously on the sand flat. The paradoxically higher growth rate of the filter-feeding Mercenaria in the lower current regime inside the seagrass bed may be a consequence of higher particulate food concentrations produced by the hydrodynamic baffling of the emergent vegetation.

28 References.

No Supplementary Data.
No Article Media
No Metrics

Document Type: Research Article

Publication date: 01 February 1984

More about this publication?
  • The Journal of Marine Research publishes peer-reviewed research articles covering a broad array of topics in physical, biological and chemical oceanography. Articles that deal with processes, as well as those that report significant observations, are welcome. In the area of biology, studies involving coupling between ecological and physical processes are preferred over those that report systematics. Authors benefit from thorough reviews of their manuscripts, where an attempt is made to maximize clarity. The time between submission and publication is kept to a minimum; there is no page charge.
  • Editorial Board
  • Information for Authors
  • Subscribe to this Title
  • Ingenta Connect is not responsible for the content or availability of external websites
  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more