Figure 1.
Drawing of the experimental set-up with views shown across the racetrack flume channel.
Table 1.
Glossary: Summary table with the description of the most important terms used in this work.
Figure 2.
Tree diagram showing the relationships among all the measured factors.
Figure 3.
Detailed drawing of the chlorophyll sampling set-up.
Figure 4.
Vector plots along the horizontal axis measured for different treatments in the physical scenario and Reynolds stress (τR) and TKE values.
The graduated grey shading outlines the extent of the patch canopies.
Figure 5.
Vector plots along the horizontal axis , measured for different treatments in the biological scenario and Reynolds stress (τR) and TKE values.
The graduated grey shading outlines the extent of the patch canopies.
Table 2.
Results of three-way ANOVA.
Table 3.
Flow velocity in the different scenarios (Phy = physical; Bio = biological), treatments and positions along the racetrack flume.
Table 4.
TKE (cm−2·s−2) and Reynolds stress (τR, Pa) values in the different scenarios (Phy = physical; Bio = biological), treatments and positions along the racetrack flume (experimental details in Figure 1).
Figure 6.
Mean values (n = 3) were interpolated along the test section (x/z plane) as a percentage (%), where 100% is the initial concentration of chlorophyll a measured following the addition of the algae culture and 0% is the total absence of chlorophyll a.
Figure 7.
Mean chlorophyll stomach content of the cockles along the racetrack flume for different treatments and scenarios.
Grey squares indicate the position of the patch (dark grey indicate high shoot density and light grey indicate low shoot density). Asterisks denote significant differences tested by the Kruskal-Wallis test (p-value<0.05). P (1–5) refers to the positions hosting the cockles along the racetrack flume.
Figure 8.
Conceptual model showing the effects of filter feeders and shoot density on resource availability and concentration.
Higher shoot densities reduce resource availability (e.g. lower volumetric flow rate) but may increase resource concentration (e.g. deposition or settling). Higher density of filter feeders will reduce resource concentration (e.g. active filtration by organisms) but also may increase biomixing. Thus, the balance between availability and concentration of resources may promote changes at the community levels (e.g. migration of species depending on resources availability).