Coastal systems provide multiple ecosystem services like food, accommodation, recreation, and protection, to name a few (Loomis & Paterson, 2014). Abundant in life supporting services, coastal system have historically been attractive to people, although overuse of these services have taken the systems to the brink of degradation. With an increasing amount of the world’s population living in coastal areas (over 680 million people, Oppenheimer et al., 2019) it is important that the limits of coastal ecosystems, especially for supporting the growing human population, are known. In addition to anthropogenic demand, external drivers like climate change related events, including sea level rise, storm surge, and floods, are accelerating coastal ecological degradation. Thus, coastal system management needs effective strategies for maintaining life supporting capacity while coping with, and protecting coastal systems from, coastal hazards (Nicholls & Cazenave, 2010).
Carrying capacity measurement is one of the commonly used tools for estimating the capacity of an ecosystem to accommodate human demand for ecological resources and services. In terms of coastal areas, carrying capacity measures are shaped by the interactions between finite resources, services available from a coastal system, and the consumers (humans and non-humans alike) of these resources (del Monte-Luna, Brook, Zetina-Rejoin, & Escalona, 2004). Methods for measuring carrying capacity vary across the different sectors, such as aquaculture and tourism, involved in coastal systems. These methods also outline how carrying capacity and coastal systems are conceptualized. These sectoral and conceptual differences can result in confusion when interpreting the outcomes of the measurements and lead to uncoordinated efforts among policy makers, practitioners, and other actors involved in coastal system management. Some efforts have been made to overcome the confusion but there is still work to be done. To fill this gap, this report intends to provide a conceptual, methodological, and analytical overview of the current understanding and utilization of carrying capacity measurements in various coastal systems worldwide. A better understanding of how carrying capacity is measured and interpreted, especially as a tool for developing sustainable management and policy recommendations, will benefit coastal system management.
This report intends to address two specific research question. The first asks how various conceptual and methodological tools (e.g., criteria, indicators, and frameworks) are used for measuring coastal carrying capacities and how they are applied to help decision making for sustainable coastal system management. This question helps illuminate the conceptual, methodological, and sectoral variabilities of carrying capacity measures while exploring the challenges of assembling different measures in a cross-sectoral decision-making process. Second, this report also examines what actions are being suggested in existing literature for coastal management systems to maintain coastal biophysical, social, and ecological carrying capacities. This question aims to explain how different carrying capacity measures across sectors can be assembled to shift from sector-based to cross-sectoral decision-making. Therefore, the outcomes of this question propose contributions to system-based decision making for coastal sustainability and ways to overcome the methodological and conceptual ambiguities of carrying capacity measures.
The results of the review include three key findings. First, the temporal, spatial, ecological, and sectoral distribution of the studies are highly skewed, with most studies having been conducted in the last decade (as of 2020), in developed nations (not including the cluster conducted in China), often focusing on beach ecosystems, and mostly encompassing the tourism sector. Results indicate that the conceptual and methodological foundations of coastal carrying capacity measures are still under development, which could be considered an opportunity to improve this tool to be more system-based and policy oriented. Moreover, developing countries, where some of the most resource abundant coastal ecosystems are located, do not devote much attention to measuring coastal carrying capacity. Furthermore, there appears to be a lack of studies conducted in non-beach/tourist coastal ecosystems and in urban areas, in spite of the growing interest in coastal studies in those areas.
Second, conceptual and methodological ambiguities need to be addressed in carrying capacity measurement for sustainable coastal system management, as otherwise these ambiguities may stand in the way of cohesive coastal policy and practices. This study notes that there remain conceptual ambiguities in defining ‘coast’ and ‘coastal carrying capacity’, with most of the studies reviewed having not explicitly defined coast and carrying capacity. This lack of clarity is a barrier to incorporating the outcomes of the studies in policy making. Also, there is a need to improve conceptual and methodological tools for measuring carrying capacity to create a list of system-based indicators that can be used across sectors and carrying capacity categories.
Third, policy recommendations should include operational strategies for attaining sustainability, which many of the studies in this report lack or do not expand on enough. Building off this, carrying capacity measurement tools should consider more action-oriented policy recommendations for maintaining coastal ecological integrity, which would allow them to be more widely applied in policy and practice by decision-makers, managers, and practitioners.
The report concludes that carrying capacity should be widely adopted for coastal system management, as it can provide specific conservation targets for policy makers. However, carrying capacity measures could be better understood and applied if their conceptual and methodological ambiguities were clarified. This study also demonstrates the need for future research into carrying capacity measures across sectors to bridge knowledge-practice gaps. Specifically, it is noted that further research on carrying capacity measures should be system-based and should aim to contribute to the development of management strategies for applying policy making and management practices.
This study adapted a methodological framework developed by Koutsos et al. (2019) to conduct a scoping review focused on coastal carrying capacity. After defining specific research questions, a set of key words were selected to identify relevant literature. The identified studies were screened using a number of inclusion and exclusion criteria, which yielded 76 studies. The final set of selected studies was analyzed using a set of analytical criteria including spatial, temporal, ecological, sectoral, conceptual methodological (e.g., categories, indicators, and frameworks), analytical, and policy recommendation aspects. This report includes a detailed description of the process and results from the research studies that were selected and analyzed in the scoping review, followed by a discussion of the findings, areas for further study, knowledge mobilization activities, and scholarly communication and knowledge dissemination.