Wetland parks are designed to support urban ecological protection, flood control and human well-being. Existing research mainly focuses on their influence on ecology and economy. However, their influence on human well-being and health is rarely studied. In China, during the peak of the COVID-19 pandemic (Peak), people were very concerned about health, while at the same time wetland parks which are generally considered beneficial to health were closed. Thus, this study explores the public’s perception of the health effects of visiting wetland parks and the impact of the pandemic on the perception. From March 5th to 8th, 2020, before the Peak in China was over, 1,400 respondents participated in a nationwide online survey. It was found that the perceived benefits from visiting wetland parks were higher in terms of mental health than in physical health. Also, the perceived health benefits of wetland parks after the Peak were slightly higher than before the pandemic. The results highlight that wildlife habitat services were considered to be the most important ecosystem services that promote the perceived health benefits. Interestingly, the perceived health benefits of wetland parks by health experts appear to be lower than in other groups, indicating that the health benefits of visiting wetland parks may be overestimated by lay-people or underestimated by health experts. The results provide empirical evidence for managing ecosystem services as delivered by these urban wetlands, in the context of COVID-19 or potential future pandemics, for promoting public health.

Introduction 1.1 Nature-Based Solutions and Perceptions of Ecosystem Services Human sustainable development is facing many challenges such as climate change, urbanization, water supply, and disaster risks. Nature-Based Solutions (NBS), which refer to actions inspired by, supported by, or copied from Nature [1] , have been proposed for coping with these challenges. NBS involves directly utilizing the ecosystems with minimum intervention and restoring the ecosystems by following natural laws. These cost-effective longterm solutions represent an interdisciplinary umbrella approach that encompasses experience from existing concepts such as "blue-green infrastructure" in Engineering, "natural capital" and "ecosystem services (ESs)" in Economics, and "landscape function" in Environmental Planning [2]~[4]. It aims to improve local ecological and social sustainability, to ensure long-term productivity [2][5] , and to sustain and potentially increase the ability to provide ESs to humans [2]. ESs are the direct or indirect benefits that people get from the ecosystem. Mainly, ESs are grouped into 4 categories: supporting, provisioning, regulating, and cultural. [6][7] There could be a cascade from ecosystem functions to ESs, and finally to benefits, indicating that the definition of an ES depends on human activities or wants [8]. Therefore, understanding public perceptions of ESs provided by NBS is crucial for the development and communication of sustainable management and policies [9]. Public satisfaction remains a key output that interests the managers of NBS projects [10] , and the participation and support of citizens in the management of blue-green infrastructure is usually upon their understanding of ESs [11]. Moreover, existing research has shown that sets of ESs could appear together repeatedly, as an ESs bundle [12]. Understanding the interconnections among ESs can help the managers with the synergy between ESs and promote management policies that improve the benefits to humans [13][14]. 1.2 Wetland Parks: A Nature-Based Solution Recent decades have seen a sharp decline and degradation of wetlands in China. From 1978 to 2008, the total area of the country's wetlands decreased by about 33% [15]. In the remaining natural wetlands, ecological functions are disappearing, and the ecosystems have deteriorated [16]. Since 2004, a large number of wetland parks (WPs), as an NBS, have been built in China to protect, compensate, and rationally utilize wetland resources [17]. Up to the end of 2017, in Chinese Mainland, a total of 1,699 WPs have been created [18]. The design and construction of WPs often employ three strategies: 1) inspired by natural wetlands (e.g., constructed vertical

Wetland parks are designed to support urban ecological protection, flood control and human well-being. Existing research mainly focuses on their influence on ecology and economy. However, their influence on human well-being and health is rarely studied. During the peak of the COVID-19 pandemic (Peak), people were very concerned about health, while simultaneously wetland parks which are generally considered beneficial to health were shut down. Thus, this study explores the publics’ perception of the health effects of visiting wetland parks and the impact of the pandemic on the perception. From March 5th to 8th, 2020, before the Peak in China was over, 1,400 respondents were surveyed online nationwide. It was found that generally, the public perceived physical and mental health benefits by visiting WPs, and perceived higher benefits in mental health than in physical health. The expected (i.e. imagined) perceived health benefits after the Peak were slightly higher than before the pandemic. The results highlight that wildlife habitat services were considered to be the most important ecosystem services that promote the perceived health benefits. Interestingly, health experts perceived health benefits to be lower from WPs than other groups, indicating that the health benefits of visiting WPs may be overestimated by lay-people or underestimated by health experts. The results provide empirical evidence for managing ecosystem services as delivered by these urban wetlands, in the context of COVID-19 or potential future pandemics, for promoting public health.

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