. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. FLOW-INDUCED FORCES IN ALGAL CANOPIES 131 o cr o LL o SOLITARY. HIGH DENSITY FLOW SPEED (ms-1) Figure 4. Force (N) as a function of flow speed (m s ') for an experimental thai Ins of Chondrus crispus when solitary (circles, solid line), in the middle of a low-density canopy (squares, long dashed line) and in the middle of a higher density canopy (triangles, short dashed line). Bars represent two standard errors about the mean; where not visible, these bars were smaller than th
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. FLOW-INDUCED FORCES IN ALGAL CANOPIES 131 o cr o LL o SOLITARY. HIGH DENSITY FLOW SPEED (ms-1) Figure 4. Force (N) as a function of flow speed (m s ') for an experimental thai Ins of Chondrus crispus when solitary (circles, solid line), in the middle of a low-density canopy (squares, long dashed line) and in the middle of a higher density canopy (triangles, short dashed line). Bars represent two standard errors about the mean; where not visible, these bars were smaller than the symbols. stream of the upstream edge (Scheffe F-tests). When the experimental thullus was placed at the upstream edge of the low density canopy it experienced only 6% lower total force than when solitary (Scheffe F-test; mean force,0 4S ms i, = N [solitary]; N [SE = N. upstream edge]; Fig. 5). Doubling the length of the stipe of this thallus in this upstream position increased the total force experienced by the thallus by 6*7r (mean force(045ms-i, = N [short]; N [SE = N. long]; /(4l = , P = ). 1983, 1987; Jackson, 1986; Duggins et «/., 1990), algal propagules (Johnson and Brawley, 1998), and surfgrass seeds (Blanchette el ui, 1999). Canopies can also influence the subsequent growth of both invertebrates (Eckman, 1987; Eckman and Duggins. 1991) and plants (Holbrook et ui, 1991; Johnson and Brawley. 1998; Koch, 1999); and the risk of flow-induced dislodgment can be altered by living in dense conspecific populations as diverse as mussels (Harger and Landenberger, 1971; Bell and Gosline, 1997) and kelp (Koehl and Wainwright, 1977). Experiments presented here show that flow-induced forces on thalli of the red alga Chondrus crispus must be considered in the context of interactions with neighboring thalli. The following discussion first examines how a soli- tary thallus of C. crispus orients in flow as velocity in- creases, and then goes on
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
