Biology Department Seminar - Tom Bell
SENG 113
Genevieve Kozak
999-9149
gkozak@umassd.edu
Giant kelp forests are highly productive, and their canopy biomass turns over several times a year, but patches separated by only a few hundred meters within a single forest can grow and decline out of phase with one another. I will show how separating physical drivers from demographic processes helps account for that variability. Reconstructing seawater nitrate from its nonlinear relationship with temperature resolves nutrient exposure at time scales that routine water sampling misses, and pairing those estimates with remotely sensed canopy pigment content (Chl:C) shows that kelp physiological condition responds to both nitrate and light and generally predicts subsequent biomass gain. Within a single forest, however, the same signal arises from the intrinsic senescence of individual fronds rather than from the physical environment, with canopy condition and frond survivorship declining together as a cohort ages. I will close with new work using the timing and magnitude of peaks in satellite-derived canopy biomass to infer cycles of cohort growth and senescence within kelp populations, evaluated against diver-based demographic surveys.