Pulsating Patches History and Analyses of Spatial, Seasonal, and Yearly Distribution of Living Benthic Foraminifera

Abstract

Within habitats the density of most organisms varies spatially and temporally. Patches are defined as density differences between stations. Pulses are defined as density differences with time (days, weeks, months, seasons, or years). When multiple samples are taken within a habitat at each sampling time, the possibility arises that we can detect that densities in space and time do not act in unison. The existence of significant statistical interaction between space and time is termed “pulsating patches.” Although our historical review and reanalysis of research on living foraminifera verified the existence of patches and pulses, the sampling design of most studies was inadequate to address the hypothesis of pulsating patches. To alleviate this deficiency, we designed an exemplar study in the Indian River Lagoon, Florida. At each of two scales, one with stations 1 m apart and another with stations 10 m apart, four stations were located in a square configuration. For each of these two studies, four sediment samples were taken at each station in the middle of each season, and this design was carried out for four years beginning in 2001. The densities of four taxa were enumerated in each sediment sample. We have then for each of four taxa, 4 replicates × 4 stations × 4 seasons × 4 years = 256 observations at each scale for each taxon. A three-way ANOVA was constructed for each taxon with hypotheses for (1) station difference, (2) seasonal difference, (3) yearly difference, and (4) their multiway interactions. The main and interaction hypotheses for station × time were significant for all taxa, which confirmed the existence of pulsating patches on varying spatial and temporal scales. Pulsating patches make the predictability of density difficult at any particular point in time and space, but this unpredictability may be a fundamental ecological strategy to a avoid reduction of populations by predators and pathogens. Because many organisms exhibit within-habitat patchiness and pulses, it is likely that they may have as yet undetected pulsating patches.