Morphometry-Driven Divergence in Decadal Changes of Sediment Property in Floodplain Water Bodies

Pongpet Pongsivapai,Hokuto Izumi,Paolo A Garrido,Junjiro N Negishi,Kanta Kuramochi

doi:10.3390/w13040469

Abstract

Sediments are potentially the internal source that supply nutrients to water in lentic to semi-lentic ecosystems. The understanding of factors that cause temporal changes in sediment properties is critical for the internal source management. This study investigated the spatial variations and temporal changes in sediment properties in relation to their controlling factors in water bodies of the Ishikari River, Northern Japan. Sediment data in 29 water bodies were measured twice (around 2005 and 2019) to study the temporal changes in sediment properties, and were compared using Generalized Linear Mixed Models (GLMMs). The controlling factors of sediment properties including catchment and morphometry were examined by partial least square (PLS) regression. Our results showed that the temporal change in sediment properties over decades was largely driven by morphometry, while land use in the catchment played a relatively minor role in those changes. The rate of change in organic matter (OM) differed among water bodies depending on their morphometry. The small and shallow water bodies provided suitable habitat for macrophytes that led to OM deposits, resulting to an increase in OM and OM to total nitrogen (TN) ratio over time. The consequences of these changes are important for internal source management and biodiversity conservation.

Highlights

The understanding of sediment quality is the key for internal nutrient management of lentic ecosystems such as lakes and ponds
The effects of observation years on land use proportion were insignificant (p > 0.99; Table S1), indicating that there were negligible changes in land use composition in catchments of the study FWBs regardless of the methods used in estimates
Numerous previous studies of land-water interaction demonstrated the negative impacts of catchment activities on water quality of lentic ecosystems including floodplain waterbodies [20,22,26]

Summary

Introduction

The understanding of sediment quality is the key for internal nutrient management of lentic ecosystems such as lakes and ponds. These water bodies receive mixtures of organic and inorganic materials that are transported from a variety of sources including the catchment and atmosphere, as well as those generated in situ by primary producers such as macrophytes and algae [1]. The deposited sediment is referred to as an internal source due to sediment-associated N and P supplied to the water column, depending on the complex biogeochemistry at sediment-water interface [5,6,7]. The effects of internal sources, in particular P, on water quality and ecosystem processes are substantial by mediating primary production and food web interactions [8], which can delay restoration processes for many years even after external stressors are controlled [6,9]

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