Assessment of coastal management options by means of multilayered ecosystem models

Abstract

This paper presents a multilayered ecosystem modelling approach that combines the simulation of the biogeochemistry of a coastal ecosystem with the simulation of its main forcing functions such as catchment loading and aquaculture activities. This modelling approach was developed as a tool for the sustainable management of coastal ecosystems. A key feature is to simulate management scenarios that account for changes in multiple uses and enable assessment of cumulative impacts of coastal activities. The model was applied to a coastal zone in China with large aquaculture production and multiple catchment uses, and where management efforts to improve water quality are under way. Development scenarios designed together with local managers and aquaculture producers include the reduction of fish cages and treatment of wastewater. Despite the reduction in nutrient loading simulated in three different scenarios, inorganic nutrient concentrations in the bay still exceed the thresholds for poor quality according to the Chinese seawater quality standards.There are still other management options to be considered given that for any of the scenarios there is still a moderate high to high portion of nutrient loads from the catchment and fish cages that can be reduced. The model predicts that overall, shellfish production decreases using any of these development scenarios (less 10% to 28%). Main reason is that shellfish growth is being sustained by the substances to be reduced for improvement of water quality. To counteract this effect the model outcomes indicate that zoning of shellfish aquaculture should be implemented at the ecosystem level to optimize productivity ratios. The present case study exemplified the value of multilayered ecosystem modelling as a tool for Integrated Coastal Zone Management and for the adoption of ecosystem approaches for marine resource management. This modelling approach can be applied worldwide, and maybe particularly useful for the application of coastal management regulation, such as in implementing the European Marine Strategy Directive.3

Modeling the coastal ecosystem complex: present situation and challenges

“…Biogeochemical models for Japanese coastal waters have also been developed (Hata et al 2004;Sohma et al 2001Sohma et al , 2004Sohma et al , 2008. Of note, the BHI concept proposed by Hori (2008) focused more on the spatial heterogeneity of habitats within a coastal area, which is different from numerical studies of biogeochemical/material cycles at larger scales, often considering areas with a homogeneous benthic habitat (Cranford et al 2007;Lacroix et al 2007;Nobre et al 2010;Xu and Hood 2006).…”

“…Benthic microalgae are also important primary producers, and in some areas their contributions to total primary production are comparable to those of phytoplankton in the water column (Underwood and Kromkamp 1999). These vegetated habitats, and other biotic habitats including coral reefs, support a variety of animals (Nishihira 2006;Onaka et al 2013). …”

Scientific approaches to address challenges in coastal management

“…Ecological modelling is recognised as an important tool for coastal management that can contribute to understanding coastal ecosystem processes and simulate management scenarios (Turner 2000, Fulton et al 2003, Greiner 2004, Hardman-Mountford et al 2005, Murawski 2007, Forst 2009, Nobre et al 2010a). Scenario testing can help managers design the most effective measures for attaining their goals.…”

“…An understanding of the cumulative impacts of natural and anthropogenic pressures on coastal ecosystem state, and on the goods and services these areas provide is crucial for coastal management (Halpern et al 2008a). Modelling approaches that are able to simulate the cumulative impacts of multiple coastal activities are still at an early stage of development (Fulton et al 2003, Ferreira et al 2008, Nobre et al 2010a). An example is the multilayered ecosystem model that combines the simulation of the biogeochemistry of a coastal ecosystem with the simulation of its main forcing functions, such as catchment loading and aquaculture activities (Nobre et al 2010a).…”

Calculation methodology of marine environmental capacity for heavy metal: A case study in Jiaozhou Bay, China

“…It may be applied further to evaluate plans for water quality management [16][17][18]. Water quality can be predicted by models based on the environmental variation in coastal areas [19].…”