Large- and small-scale effects of habitat structure on rates of predation: how percent coverage of seagrass affects rates of predation and siphon nipping on an infaunal bivalve

Experiments were designed to address how percent coverage of seagrass in a 100-m2 area of seafloor, and the spatial arrangement (degree of patchiness or fragmentation) of an equal area (100 m2) of vegetation affected predation (lethal) and siphon nipping (sublethal) intensity on an infaunal bivalve,...

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Bibliographic Details
Published in:Oecologia 1994-07, Vol.98 (2), p.176-183
Main Author: Irlandi, E.A. (North Carolina Univ. at Chapel Hill, Morehead City (USA). Inst. of Marine Sciences)
Format: Article
Language:English
Subjects:
Animal and plant ecology
Animal organs
Animal, plant and microbial ecology
Biological and medical sciences
Biomass
Clams
ECOLOGIA ANIMAL
ECOLOGIE ANIMALE
Energy flow
Foraging
Fundamental and applied biological sciences. Psychology
GRAMINEAS
GRAMINEE
HABITAT
Habitat structure
Landscape ecology
Marine
Marine ecology
MERCENARIA
Mercenaria mercenaria
Ocean floor
PAISAJE
PAYSAGE
Predators
Scale
Sea water ecosystems
Sediments
SUPERVIVENCIA
SURVIE
Synecology
VEGETACION
VEGETATION
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Summary:Experiments were designed to address how percent coverage of seagrass in a 100-m2 area of seafloor, and the spatial arrangement (degree of patchiness or fragmentation) of an equal area (100 m2) of vegetation affected predation (lethal) and siphon nipping (sublethal) intensity on an infaunal bivalve, Mercenaria mercenaria (hard clam). Measures of seagrass density and biomass with different percent coverage of seagrass were also made. When clams were placed in both the vegetated and unvegetated portions of the seafloor nearly twice as many clams were recovered live with 99% seagrass cover than with 23% seagrass cover, while survivorship was intermediate with 70% cover. Cropping of clam siphons from both the vegetated and unvegetated sediments was also affected by the amount of seagrass cover in a 100-m2 area of seafloor: mean adjusted siphon weights were approximately 76% heavier from the 99% seagrass cover treatment than from the 70% or 23% cover treatments. Survivorship of clams placed within an equal area of seagrass in very patchy, patchy, and continuous spatial configurations was 40% higher in the continuous seagrass treatment than in either of the two patchy treatments. This study demonstrates that transfer of secondary production in the form of predation and cropping on an infaunal organism is altered as the percent cover of seagrass changes
ISSN:0029-8549
1432-1939
DOI:10.1007/bf00341470