Design features of constructed floodplain ponds influence waterbird and fish communities in northern New Zealand

Abstract

1. Ponds can provide important refuges for aquatic biota on developed floodplains and are increasingly being constructed in an effort to enhance native biodiversity and ecosystem services in degraded landscapes. This study examined 34 constructed ponds to investigate the influence of design features on community composition, native biodiversity, and the biomass or abundance of common fish and waterbirds on the lower Waikato River floodplain, northern New Zealand. 2. Inundation frequency appeared to be a key factor affecting biomass of the native shortfin eel Anguilla australis and three invasive fish species (common carp [Cyprinus carpio], brown bullhead [Ameiurus nebulosus], and goldfish [Carassius auratus]), suggesting that colonisation occurred during flooding by adjacent waterbodies. Linear models indicated that shortfin eel abundance and total eel biomass were positively associated with the biomass of potential fish prey, the area occupied by islands and cover by trees in the riparian zone. 3. Native waterbird species richness was strongly related to water area, edge length (including islands) and area:perimeter ratio, with little increase in richness for ponds >1 ha in area, perimeters longer than 800 m, and ratios over 20. The protected grey teal (Anas gracilis), and the recreationally hunted species phenotypically assigned as mallard (Anas platyrhynchos + hybrids) and grey duck (Anas superciliosa + hybrids) appeared most strongly influenced, respectively, by perimeter length, water depth, and biomass of potential macroinvertebrate food supplies, suggesting variable effects of pond design attributes among waterfowl species. 4. Overall, these results indicate that constructed ponds can be designed to promote native waterbird diversity, enhance eel fishery and waterfowl gamebird services, and also limit the proliferation of some non-native invasive fish species in degraded floodplain landscapes. A hierarchy of constructed pond design attributes was identified, involving landscape position and connectivity, pond morphology and complexity, and riparian maturity and buffering, which were associated with direct (habitat) and indirect (food supply, physicochemistry) effects on biodiversity and provisioning services. | 2067 GARRETT-WALKER ET AL. 1 | INTRODUC TI ON Functional riverine floodplains provide complex arrays of aquatic habitats that support high biodiversity and a range of ecosystem services (Amoros & Bornette, 2002; Hornung, Podschun, & Pusch, 2019; Schindler et al., 2014). These environments have been degraded worldwide due to activities such as flood control, drainage, and land use intensification (e.g.

Nestedness theory suggests wetland fragments with large areas and macrophyte diversity benefit waterbirds

“…Therefore, combined with the requirement for stormwater runoff (Malaviya and Singh, 2012 ) or pollution abatement efficiency (Nivala et al., 2018 ), wetland construction must integrate more ecosystem services (Kim et al., 2011 ). For improved waterbird conservation, we suggest that future studies should aim to quantify the appropriate wetland area, according to waterbird composition characteristics and their life history, to determine the smallest area necessary for constructing artificial wetlands in given regions (Garrett‐Walker et al., 2020 ). Moreover, vegetation configuration, which affects waterbird composition (Wang et al, 2020 ), usually varies with ecological succession.…”

Surviving Invasion: Regaining Native Fish Resilience Following Fish Invasions in a Modified Floodplain Landscape

“…(2016), and Garrett‐Walker et al. (2020), respectively. Data presented in Figures 1 and 5 are publicly available from Waikato Regional Council, Hamilton, New Zealand (https://www.waikatoregion.govt.nz/).…”

“…Garrett‐Walker et al. (2020) identified several design features of LWRF constructed ponds influencing the fish community structure and the abundance or biomass of particular species, including landscape position, the area of islands, depth regimes and riparian vegetation composition. Connectivity in the form of inundation frequency had positive effects on invasive carp, goldfish and brown bullhead, and negative effects on gambusia abundance.…”

“…This species inhabits benthic littoral habitats and can represent an important food resource for both native and invasive predatory fish (Collier et al., 2018). Common smelt ( Retropinna retropinna Richardson, 1848; Retropinnidae), which occurs in riverine habitats as well as floodplain lakes, wetlands and occasionally ponds (Garrett‐Walker et al., 2020; Górski et al., 2014), can also have diadromous and non‐diadromous populations, although non‐diadromous lacustrine populations are believed to have succumbed to habitat and water quality changes in some lakes (Northcote & Chapman, 1999).…”

Hydrological Assessment of the Water Replenishment Possibility of the Uzh River Urbanized Floodplain on the Example of Bozdosky Park, Ukraine

“…Now we have some experience of water replenishment of the floodplains outside residential areas, in the work by [Chen et al, 2020] presented the observations results of the replenishment impact on the Zhalong wetland (China), the biodiversity increased over 19 years, the assessment of water balance components showed that 64% of biomass growth was formed in the summer months due to precipitation, 25% due to water replenishment and 11% due to river flooding, the frequency of the water replenishment affected biodiversity. In the work by [Garrett-Walker et al 2020] it was also emphasized that the biodiversity of the floodplain lake was affected by flooding intensity and the waterbody size, the biodiversity increased if the area of the lake was more than 1.0 ha and the lake perimeter was more than 800 meters. The observations of the water quality in the oxbow lakes, which were connected and isolated from the river, during the vegetation season were carried out by [Wang et al 2020], the study showed that isolated oxbow lakes had higher concentrations of dissolved oxygen and nutrients, which led to eutrophication of the lakes, at the same time water quality significantly improved in lakes after the floods, which indicates the positive impact of the water replenishment.…”