Spatio-temporal nested patterns in macroinvertebrate assemblages across a pond network with a wide hydroperiod range

Abstract

Nestedness has been widely used to measure the structure of biological communities and occurs when species-poor sites contain subsets of species-rich ones. Here, we examine nested patterns across the macroinvertebrate assemblages of 91 ponds in Doñana National Park, Spain, and explore temporal variation of nestedness and species richness in 19 temporary ponds over 2 years with differing rainfall. Macroinvertebrate assemblages were significantly nested; both pond spatial arrangement and environmental variation being important in driving nested patterns. Despite the nested structure observed, a number of taxa and ponds deviate from this pattern (termed idiosyncratic), by occurring more frequently than expected in species-poor sites, or having assemblages dominated by species largely absent from species-rich sites. Aquatic adults of winged insects, capable of dispersal, were more highly nested than non-dispersing taxa and life-history stages. Idiosyncratic taxa were found in ponds spanning a wide range of hydroperiods, although nestedness was higher in more permanent waterbodies. Monthly sampling demonstrated a gradual increase of species richness and nestedness from pond filling to April-May, when the most temporary ponds started to dry. Although the degree of nestedness of individual pond assemblages varied from month to month, the overall degree of nestedness in the two study years was practically identical despite marked differences in hydroperiod. Our results suggest that differential colonization and environmental variation are key processes driving the nested structure of Doñana ponds, that macroinvertebrate assemblages change in a predictable manner each year in response to cycles of pond wetting and drying, and that connectivity and environmental variability maintain biodiversity in pond networks.

How do freshwater organisms cross the “dry ocean”? A review on passive dispersal and colonization processes with a special focus on temporary ponds

“…As observed by Ebert & Balko (1987) and Florencio et al (2011), isolation in time, as resulting from the different length of hydroperiod among the ponds of a network, can give similar patterns to those observed when it occurs in space, further confirming that both pond density and hydroperiod length in a given area are important in determining the colonization chances (Ruhí et al, 2013).…”

“…Conversely, in a study carried out in a network of temporary ponds, Eitam et al (2004) found that crustacean species richness was positively related to hydroperiod length but not to surface area. This result could be explained by the assumption that increased isolation of ponds due to the progressive disappearing of the aquatic habitat during the dry phase, as it may occur in a network of temporary ponds with different hydroperiods, can limit local immigration and unbalance the immigration/extinction patterns generating nested patterns of ponds with species-poor sites containing a subset of species-rich sites (Florencio et al, 2011). The degree of nestedness thus quantifies the overlap in species composition between high and low diversity areas (McAbendroth et al, 2005).…”

Relationships between hydroperiod length, and seasonal and spatial patterns of beta-diversity of the microcrustacean assemblages in Mediterranean ponds

“…Doñana's temporary ponds have been revealed to be a robust and interconnected network when it comes to the dispersal of macroinvertebrates and their recolonisation of ponds (Florencio et al, 2011). Therefore, we consider it improbable that, in our study, dispersal limitations would be driving changes in microcrustacean assemblages.…”

Effect of Protection Level in the Hydroperiod of Water Bodies on Doñana’s Aeolian Sands

“…It is considered a single aquifer from the perspective of groundwater dynamic although it has been recently divided in 5 sections from a water management point of view [7]. The Doñana's system of Mediterranean temporary ponds on the aeolian sands has received substantial attention from the perspective of its hydrology [8,9], geomorphology [10][11][12], relation to groundwater [4,13,14], water chemistry [15,16], biodiversity [17][18][19][20] but most studies have been conducted in a few ponds and only for a few years.…”