ABSTRACT Ants are a major ecological group in tropical rainforests. Few studies in the Neotropics have documented the distribution of ants from the ground to the canopy, and none have included the understorey. A previous analysis of an intensive arthropod study in Panama, involving 11 sampling methods, showed that the factors influencing ant beta diversity (i.e., changes in assemblage composition) were, in decreasing order of importance, the vertical (height), temporal (season), and horizontal (geographic distance) dimensions. In the present study, we went one step further and aimed (1) to identify the best sampling methods to study the entire ant assemblage across the three strata, (2) to test if all strata show a similar horizontal beta diversity and (3) to analyze the functional structure of the entire ant assemblage. We identified 405 ant species from 11 subfamilies and 68 genera. Slightly more species were sampled in the canopy than on the ground; they belonged to distinct sub-assemblages. The understorey fauna was mainly a mixture of species found in the other two strata. The horizontal beta diversity between sites was similar for the three strata. About half of the ant species foraged in two (29%) or three (25%) strata. A single method, aerial flight interception traps placed alongside tree trunks, acting as arboreal pitfall traps, collected half of the species and reflected the vertical stratification. Using the functional traits approach, we observed that generalist species with mid-sized colonies were by far the most numerous (31%), followed by ground- or litter-dwelling species, either specialists (20%), or generalists (16%), and arboreal species, either generalists (19%) or territorially dominant (8%), and finally army ants (5%). Our results reinforce the idea that a proper understanding of the functioning of ant assemblages requires the inclusion of arboreal ants in survey programs.
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Suspended particulate matter (SPM) is abundant and essential in marine and coastal waters, and comprises a wide variety of biomineral particles, which are practically grouped into organic biomass and inorganic sediments. Such biomass and sediments interact with each other and build large biomineral aggregates via flocculation, therefore controlling the fate and transport of SPM in marine and coastal waters. Despite its importance, flocculation mediated by biomass-sediment interactions is not fully understood. Thus, the aim of this research was to explain biologically mediated flocculation and SPM dynamics in different locations and seasons in marine and coastal waters. Field measurement campaigns followed by physical and biochemical analyses had been carried out from 2004 to 2011 in the Belgian coastal area to investigate bio-mediated flocculation and SPM dynamics. Although SPM had the same mineralogical composition, it encountered different fates in the turbidity maximum zone (TMZ) and in the offshore zone (OSZ), regarding bio-mediated flocculation. SPM in the TMZ built sediment-enriched, dense, and settleable biomineral aggregates, whereas SPM in the OSZ composed biomass-enriched, less dense, and less settleable marine snow. Biological proliferation, such as an algal bloom, was also found to facilitate SPM in building biomass-enriched marine snow, even in the TMZ. In short, bio-mediated flocculation and SPM dynamics varied spatially and seasonally, owing to biomass-sediment interactions and bio-mediated flocculation.
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