Phytoplankton depletion in the benthic boundary layer caused by suspension-feeding Nereis diversicolor (Polychaeta):grazing impact and effect of temperature

1998 ◽  
Vol 171 ◽  
pp. 125-132 ◽  
Author(s):  
A Vedel
Keyword(s):  
Boundary Layer ◽  
Effect Of Temperature ◽  
Grazing Impact ◽  
Benthic Boundary Layer ◽  
Suspension Feeding ◽  
Nereis Diversicolor

Phanerozoic development of tiering in soft substrata suspension-feeding communities

Paleobiology ◽  
1986 ◽  
Vol 12 (4) ◽  
pp. 400-420 ◽  
Author(s):  
David J. Bottjer ◽  
William I. Ausich
Keyword(s):  
Boundary Layer ◽  
Benthic Boundary Layer ◽  
Suspension Feeding ◽  
Velocity Gradients ◽  
Phylogenetic Constraints ◽  
Recent Brachiopods ◽  
Shallow Subtidal ◽  
The Vertical Distribution ◽  
Sediment Interface

Tiering is the vertical distribution of organisms within the benthic boundary layer. Primary tierers are suspension-feeding organisms with a body or burrow that intersects the seafloor. Secondary tierers are suspension-feeders that maintain positions above or below the sediment-water interface as either epizoans on primary tierers and plants or by living in the burrows of primary tierers. Different primary tierers from soft substrata, nonreef, shallow subtidal shelf and epicontinental sea settings have had different tiering histories, resulting largely from contrasting constructional and phylogenetic constraints. Primary colonial tierers generally occupied lower epifaunal tiers during the Paleozoic and Mesozoic, but since the Cretaceous they have been dominant in the highest tier (+ 20 to +50 cm). Primary echinoderm tierers have been almost exclusively epifaunal, and from the Paleozoic through the Jurassic they were present throughout the epifaunal tiered structure. Although primary bivalve tierers have been both epifaunal and infaunal, they have occupied only lower epifaunal tiers, whereas they have adapted to all levels of the infaunal tiering structure, particularly from the late Paleozoic through the Recent. Brachiopods have lived primarily in tiers directly above or below the water-sediment interface and have not contributed significantly to tiering complexity.Of the numerous physical and biotic processes and constraints that affect shallow marine benthos, a few have contributed more significantly to changes in tiering patterns. Trends for increasing body size could have accounted for most of the development of tiering complexity up to +50 cm and down to –12 cm. Development of tiering above +50 cm could have been due to processes which would have yielded greater feeding capability, such as competitive interactions for a place from which to feed or adaptations to velocity gradients in the hydrodynamic boundary layer. The most significant process for development of infauanl tiering below –12 cm appears to have been as an adaptive response for predator avoidance.Unlike infaunal tiering, which never declined after it developed, epifaunal tiering has undergone a general reduction twice. Reduction in epifaunal tiering at the end of the Paleozoic appears to have been the result of the mass extinction at this time, whereas long-term biotic processes seem to have been more important for the tiering decline at the end of the Mesozoic. Tiering structure through the Phanerozoic was thus produced through interactions of a number of physical and biotic factors, tempered by constructional and phylogenetic constraints of each primary tierer group.

Importance to Mussels of the Benthic Boundary Layer

1984 ◽  
Vol 41 (11) ◽  
pp. 1618-1625 ◽  
Author(s):  
D. J. Wildish ◽  
D. D. Kristmanson
Keyword(s):  
Boundary Layer ◽  
Food Supply ◽  
Blue Mussel ◽  
Mutual Exclusion ◽  
Staining Technique ◽  
Benthic Boundary Layer ◽  
Sampling Location ◽  
Suspension Feeding ◽  
Acridine Orange Staining ◽  
Horse Mussel

We examined whether populations of the blue mussel Mytilus edulis (Linnaeus, 1758) and horse mussel Modiolus modiolus (Linnaeus, 1758) could, by their feeding activities, deplete the sestonic food supply. The experiments were conducted in a 5-m-long by 50-cm-wide flume in which a turbulent boundary layer flow was created. The seston concentration was measured both as ATP content and numbers of bacteria by acridine orange staining technique on separate subsamples of seawater. Sampling locations were at the flume inlet and at a point 3.6 m downstream (outlet). Four of the five replicated experiments with blue mussels had significant ATP–seston depletion but no reduction in bacterial numbers at the outlet sampling location. Of three replicated experiments with horse mussels, two had significant ATP–seston depletion and all three had significantly fewer bacterial numbers at the outlet sampling location. We consider that these results provide direct evidence in support of the hypothesis that seawater hydrodynamic factors may be critical in determining the food supply available to suspension-feeding animals. Our results confirm circumstantial evidence on this point obtained from field observations by previous investigators. Experimental verification of seston depletion is a necessary, but not sufficient, step in establishing that suspension-feeding animals may be food limited as required by the trophic group mutual exclusion hypothesis.

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