Seasonal and spatial hydrological variability drives aquatic biodiversity in a flood‐pulsed, sub‐tropical wetland

Abstract

Summary 1. Flood‐pulsed wetlands make vital contributions to local and global biodiversity. However, the patterns and controls of spatial and temporal variation in aquatic biodiversity in flood‐pulsed wetlands are not well understood. We analysed the relationship between variation in hydrological regime and the patterns of aquatic biodiversity in a large pristine flood‐pulsed wetland, the Okavango Delta, Botswana. 2. Surveys of water chemistry, diatoms and macroinvertebrates were conducted over the seasonal phases of the flood pulse. Hydrological variables of flood frequency and hydroperiod class were collated from 16 years of satellite images. Multivariate regression trees and generalised least squares regression were used to determine the chief controls of community composition and taxon richness. 3. Hydroperiod class, phase of the flood and conductivity explained 32% and 43% of the variation in diatom and invertebrate taxon richness, respectively. There was a negative relationship between hydroperiod class and invertebrate taxon richness on the rising, peak and receding flood, whereas at low flood there was no significant relationship. Multivariate regression tree analysis revealed hydroperiod class, phase of the flood and conductivity as the dominant forces shaping invertebrate and diatom community composition. 4. Seasonal and spatial variation in hydrological conditions are the principal drivers of variation in aquatic biodiversity in flood‐pulsed wetlands. In pristine flood‐pulsed wetlands, increased productivity caused by the arrival of the flood waters appears to override disturbance and connectivity in shaping taxon richness and community composition. Thus, these data suggest that the maintenance of a rich mosaic of habitats covering a broad range of hydroperiod is the key to preserving aquatic biodiversity and natural ecosystem function in flood‐pulsed wetlands.

Community structure and decadal changes in macrozoobenthic assemblages in Lake Poyang, the largest freshwater lake in China

“…Therefore, an improved understanding of macrozoobenthic assemblages is highly significant for developing efficient conservation and management strategies for floodplains. As is well-known, the distribution of benthic invertebrates in floodplain systems is influenced by abiotic habitat parameters such as water depth, current velocity, substratum stability, and grain size (Thomaz et al, 2007;Davidson et al, 2012;Negishi et al, 2012). Johnson et al (2004) showed that the variation of macrozoobenthic communities across sites in lakes is best explained by habitat-scale characteristics.…”

The biological, ecological and conservation significance of freshwater swamp forest in Singapore

“…How water flows is a major determinant of geomorphological, biological and biogeomorphological processes and functions within aquatic ecosystems (Poff et al, 1997;Bunn & Arthington, 2002;Davidson et al, 2012;Fig. 1).…”

“…When the monsoon season arrives, heavy rains can create flood pulses which integrate terrestrial and aquatic systems (Davidson et al, 2012). Junk et al (1989) stressed the importance of seasonal flood pulses through effects such as over-bank flooding, which strongly influences biological community structure through allochthonous inputs and changing of the physical habitat (Douglas et al, 2005;Davidson et al, 2012).…”

“…When the monsoon season arrives, heavy rains can create flood pulses which integrate terrestrial and aquatic systems (Davidson et al, 2012). Junk et al (1989) stressed the importance of seasonal flood pulses through effects such as over-bank flooding, which strongly influences biological community structure through allochthonous inputs and changing of the physical habitat (Douglas et al, 2005;Davidson et al, 2012). For example, in Brazilian floodplains da Silva et al (2010) found that turbid and anoxic water conditions dominated in the high water season compared to low or falling water seasons, which had relatively well oxygenated and low turbid waters.…”

Operational Actual Wetland Evapotranspiration Estimation for South Florida Using MODIS Imagery

“…It is known that hydrological variables such as water flow velocity, flow duration, flow variability, hydroperiod, and evapotranspiration play important roles in the ecosystem dynamics of wetlands (Cole and Brooks, 2000;Gurnell et al, 2000;Price et al, 2000;Melesse et al 2006Melesse et al , 2007. Water impacts several major aspects of wetland health including soil composition (Faulkner, 1989;Venterink, 2002), vegetation cover (van der Valk, 1994Todd, 2010;Cooper, 2012), and wildlife diversity (Bunn, 2002;Davidson, 2012;Konar, 2013). Clearly, hydrological factors affect every major ecological aspect of wetlands.…”