The advance in science and technology, and population growth have increased human use and development of the ocean. The increased use has lead to changes in the marine environment, and excessive use has had a negative impact on marine ecosystems. In addition, various activities have been carried out in the sea, causing some of them to be in conflict with others. In general, human activities act as a pressure on the marine environment, and these pressure factors directly or indirectly affect the marine environment. Such human activities that affect demand for marine resources and marine ecosystems can reduce the diverse benefits of the ocean.
Existing sectoral management approach for ocean have limitations in solving these problems. That is because the sectoral management approach considers the impacts of individual activities but cannot take into account the combined impact of activities taking place around them. Therefore, political approaches have been taken to identify the impact of human beings on the ocean and to determine an appropriate scale and level of marine use. This study focuses on marine spatial planning(MSP) among those political alternatives. MSP, one of the diverse approaches to sustainable marine use, is a process of allocating spaces to minimize adverse impacts of marine use and development and prevent conflicts between various uses and development activities. To manage utilization and development activities in a certain space at an appropriate level, a spatial analysis tool is required that is capable of identifying impacts of various utilization and development activities on marine ecosystems and diagnosing socioeconomic interactions.
The purpose of this study is to develop a methodology for integrating cumulative impact assessment and agent-based modeling(ABM) to measure the impact of human activities on the ocean. And this study presented a cumulative impact assessment method appropriate to our situation in which there is lack of information on human activities and information on linking human activity-pressure-marine ecosystem components. Based on assumptions discussed in the previous cumulative impact assessments, a method of processing human use mapping in ocean, which is necessary for cumulative impact assessment in Korea, was formulated and then applied to a research area of this study.
Gyeonggi Bay, a research area, is a suitable marine space to which cumulative impact assessment and ABM simulation can be applied because various utilization, development and conservation needs that can occur in the Korean ocean exist in the area. The areas of Gyeonggi Bay not only produce crabs but also are abundant in marine aggregates resources, thereby causing competition between the two activities. Gyeonggi Bay is a maritime space where information on cumulative impacts of human activities and interactions between the activities is needed to solve those problems and provide appropriate measures.
In this study, a list of eleven human activities affecting the ocean, particularly the research area, was set up. The data of the human activities were converted to grid-based spatial information, which is easy to analyze, through the geographic information system(GIS). Since marine ecosystems and marine species have different vulnerabilities depending on human uses, vulnerability weights per marine ecosystem component were incorporated into the cumulative impact assessment. In the absence of available marine ecosystem information, three marine ecosystem components (pelagic ecosystem, benthic ecosystem(soft), benthic ecosystem(hard)) were considered. The relationships between human activities, pressures and marine ecosystem components are essential for a reliable cumulative impact assessment. However, there has not been much research to identify and confirm such relationships in Korea. In this study, marine ecosystem weights were applied based on previous studies that attempted to establish a generalized linkage between human activities, pressures, and marine ecosystem components. Then, the final cumulative impact scores and map were generated by reflecting the information established in the cumulative impact formula presented by Halpern et al.(2008).
Following the identification of cumulative impacts in the research area, a methodology for constructing a simulation model for identifying environmental, social, and economic impacts using ABM was established, and the model was constructed. This model was used in predicting environmental, social, and economic changes arising due to marine aggregate extraction and fisheries activities, which are pending issues in Gyeonggi Bay. It will be possible to find appropriate spatial management alternatives by comparing and analyzing the results found with the sea sand extraction and fisheries activity scenarios.
The simulation model constructed in this study not only can predict repeatedly and quantitatively results of a cumulative impact assessment according to changes in human activities but also can be used in examining the interactions of ecosystem services(supply of fisheries resources and aggregate resources) according to individual human activities. By constructing the cumulative impact assessment and the simulation model, this study could confirm the applicability and limitations of the MSP in Korea.
The method presented in this study provides an effective management system for the MSP because it can help to understand the interrelationships among the environment, economy and society and to improve capabilities of decision making and problem solving concerning the environment. It will be a useful tool to support scientific and systematic decision making by showing at a glance the impact of human activities on the ocean and exploring temporally and spatially the environmental, social and economic changes in various activities occurring in the ocean.