Data from: A cross-scale trophic cascade from large predatory fish to algae in coastal ecosystems

Trophic cascades occur in many ecosystems, but the factors regulating them
are still elusive. We suggest that an overlooked factor is that trophic
interactions (TIs) are often scale-dependent and possibly interact across
spatial scales. To explore the role of spatial scale for trophic cascades,
and particularly the occurrence of cross-scale interactions (CSIs), we
collected and analysed food-web data from 139 stations across 32 bays in
the Baltic Sea. We found evidence of a four-level trophic cascade linking
TIs across two spatial scales: at bay scale, piscivores (perch and pike)
controlled mesopredators (three-spined stickleback), which in turn
negatively affected epifaunal grazers. At station scale (within bays),
grazers on average suppressed epiphytic algae, and indirectly benefitted
habitat-forming vegetation. Moreover, the direction and strength of the
grazer–algae relationship at station scale depended on the piscivore
biomass at bay scale, indicating a cross-scale interaction effect,
potentially caused by a shift in grazer assemblage composition. In
summary, the trophic cascade from piscivores to algae appears to involve
TIs that occur at, but also interact across, different spatial scales.
Considering scale-dependence in general, and CSIs in particular, could
therefore enhance our understanding of trophic cascades.