Effects of Changes in Seawater and Sedimentary Environment on Vegetation Growth and Macrozooplankton and Macrobenthos Communities of Eelgrass Meadows in Northern China

Abstract

Seagrass meadows, along with their associated zooplankton and benthic fauna, have been significantly affected by climate change and human disturbances in recent years. However, the impacts of these changes on seagrass and related macroinvertebrates remain poorly understood. To address this gap, we examined the growth patterns of Zostera marina and the diversities of macrozooplankton and macrobenthos (both α- and β-diversity) across an environmental gradient in the seascape. The research results showed that the density of seagrass plants was significantly positively correlated with inorganic nitrogen and dissolved oxygen levels, and significantly negatively correlated with inorganic phosphate and suspended solids levels. The species diversities of macrozooplankton and macrobenthos in seagrass meadows were more strongly influenced by environmental factors than by the growth status of seagrass, with the influence of environmental factors showing a cascade effect. The α-diversities of both macrozooplankton and macrobenthos showed a significant negative correlation with seawater temperature. Additionally, water temperature significantly affected the β-diversities of both groups, with detritivorous macrobenthos showing a strong negative correlation. The distribution of macrozooplankton and macrobenthos was also influenced by seawater nutrient content (inorganic nitrogen and active phosphate) and seagrass density. Furthermore, macrozooplankton were affected by water transparency, suspended solids, and dissolved oxygen levels, while macrobenthos were further influenced by the type of benthic habitat. This study addresses a current scientific gap regarding the relative contributions of seagrass condition and environmental factors to the biodiversity of macroinvertebrates in temperate Z. marina meadows.

Keywords: seagrass meadow, planktonic communities, benthic communities, α-diversity, β-diversity, environmental factors