Does the Structural Complexity of Aquatic Macrophytes Explain the Diversity of Associated Spider Assemblages?

Abstract

Differences in species richness and species composition of spiders associated with aquatic macrophytes of different structural complexities were examined in the Pantanal floodplain of Mato Grosso do Sul, Brazil. The plants studied were Nymphaea amazonum (Nymphaeaceae), Salvinia auriculata (Salviniaceae), Echinodorus paniculatus (Alismataceae) and Eichhornia azurea (Pontederiaceae), whose classes of complexity were determined based on their leaf and branch densities, vertical structure, and height. Data were collected from 62 monospecific plant patches in temporary lentic environments. A total of 235 spiders of 33 species in 13 families was collected. Nymphaea amazonum, the plant with the lowest complexity class, did not provide adequate sites for the establishment of spiders, and only four individuals of four spider species were found on its patches. Salvinia auriculata and E. paniculatus shared the intermediate class of complexity, but showed statistically significant differences in composition and richness of spider species. In E. paniculatus, greater height and lower leaf and branch densities favored the establishment of web weavers, whereas the smaller height and higher density of S. auriculata promoted the occurrence of wandering spiders. Eichhornia azurea, the plant with the highest complexity class, presented the greatest number of unique spider species, differing from the other plants in spider species composition. Results indicate that richness and composition of spider species associated with aquatic macrophytes in the study site are influenced by the structural complexity of these plants.

Spider assemblage (Arachnida: Araneae) associated with canopies of Vochysia divergens (Vochysiaceae) in the northern region of the Brazilian Pantanal

“…The distribution and species richness of predators like spiders may be influenced by the structural conditions of the host plants even though they do not generally have a direct relationship with these plants (raizer & aMaral 2001, souza & Martins 2004, souza & Módena 2004, or by changes in environmental conditions (Wolda 1988). Spiders depend on plant structures to attach their webs and to forage.…”

Experimental evaluation of preferences of an invasive Ponto-Caspian gammarid Pontogammarus robustoides (Amphipoda, Gammaroidea) for mineral and plant substrata

“…Aquatic habitats are structured by different types of natural substrates, such as stones, leaves, branches, macrophytes and artificial substrata, such as solid waste materials, all of which exhibit positive effects on invertebrate diversity (Cooper et al, 1997;Scealy et al, 2007;Czarnecka et al, 2009). Macrophytes increase the availability of food and shelters, elevating the diversity of aquatic assemblages (Raizer & Amaral, 2001;Taniguchi et al, 2003;Thomaz et al, 2008). Temperate shores throughout the world are dominated by macrophytes (Foster et al, 2003;Schiel, 2004).…”

Comunidade edáfica de Araneae (Arthropoda, Arachnida) em uma floresta sazonalmente inundável na região Norte do Pantanal de Mato Grosso, Brasil

“…Apesar da importância dos estudos que evidenciem a interação entre as comunidades de invertebrados e as condições ambientais no Pantanal de Mato Grosso, as pesquisas que abordam as comunidades de Araneae, referem-se a associações destes organismos à estruturas florais de diferentes espécies (Souza & Módena 2004), com macrófitas aquáticas (Raizer & Amaral 2001) e copas de palmeiras (Battirola et al 2004, Santos et al 2003, além de outros estudos que analisaram a similaridade entre a fauna pantaneira e amazônica (Raizer & Amaral 2001), ou ainda a estratificação vertical em área de vegetação monodominante (Castilho et al 2005, Marques et al 2010. Assim, poucos são os dados registrados para a fauna edáfica e seu comportamento sazonal.…”