Animal-Sediment relationships reexamined, a meta-analysis

The patterns associated with the influence of grain size on the spatial variation of the deposit and suspension-feeding groups have been studied since the late 1950s. The foundational paper for the theory, Sanders (1958), proposed that a higher proportion of clay and silt-sized grains in the sediments correlates with a higher proportion of deposit feeders compared to suspension feeders. This theory has become widely accepted and taught in textbooks despite subsequent papers indicating differing observations. Through a meta-analysis, this study examines whether the observation from Sanders (1958) was indicative of a general rule or an anomaly. Additionally, this study aims to determine that this spatial distribution pattern covaries with food availability in the water column, measured by surface chlorophyll content gathered via satellite data using a meta-regression. The meta-analysis found the general effect size of grain size, measured as percent silt-clay, was a correlation coefficient of 0.13 across the nine studies, indicating that a high proportion of fine grain sediment is not a consistent measure of increases in deposit feeder abundance. The meta-regression did not reveal any pattern associating the effect sizes of the individual studies with surface chlorophyll concentration, suggesting that chlorophyll concentration is not a covarying factor influencing the spatial variation of feeding modes. While the pattern associating grain size with feeding mode spatial variation was determined not to covary with surface chlorophyll concentrations, other factors may include facultative feeding, larval dispersal, trophic group amenalism, and interactions with predators. Regardless, the pattern observed by Sanders (1958) is not generalizable and the inclusion of this pattern in textbooks should be retired.