The Importance of Marine Bio-geochemical Modelling In Devising Indonesian Climate-adaptation Plan

The importance of marine bio-geochemical modelling in devising Indonesian climate-adaptation plan

By:

Prima Anugerahanti & Shovonlal Roy

Department of Geography and Environmental Science

University of Reading

Russell Building, Whiteknights,

Reading, RG6 6DW

Indonesia is an archipelagic country; it consists of the sea and thousands of islands. The nation is surrounded by 81,000 km of coastline and 51,000 km² of coral reefs [1]. A huge part of Indonesian population rely on the coastal area and marine ecosystem. In 2005, 8% of the working population were working within the marine fisheries sector [2] contributing US$ 5.2 billion to Indonesia’s gross domestic product [3]. Therefore health of the coastal and marine ecosystem is essential to their living [4]. However environmental and climatic changes are constant threat to these ecosystems. Global climate change, caused by the increase of carbon dioxide (CO₂) amongst other greenhouse gases, is a major driver of ocean acidification [5] with potentially significant impact on marine resources. CO₂ concentration has now exceeded the maximum values, 380ppm, for the past 740,000 years (Raven et al., 2005). There has been an increase (from 0.7⁰C/100 years in 1905, to 1.5⁰C/100 years since 1945) in sea surface temperature and sea surface height (from 1.6 mm/year in 1960, to 7 mm/year in 1993) in Indonesian waters [6]. Western-Indo Pacific region is susceptible to harmful algae that could cause paralytic shellfish poisoning [7, 8]. It has been reported that harmful bloom events in Indonesia are increasing in number [9] which may pose a serous public health and economic problem, especially for a country whose population depend on seafood for protein. Furthermore, fish catches in Indonesia have been predicted to suffer a decline by over 20% until 2055, and may experience the strongest decline in fish catches [10]. Coastal communities are therefore very vulnerable to the impacts of marine degradation, both due to climate change and human activities.

Although various means of addressing sensitivity and adaptive capacity of coastal communities to marine resource degradation are incorporated in the national policy framework, vulnerability in the coastal area remains high, low resilience, making the policy ineffective [11, 12]. For example according to Ferrol-Schulte et al. [12] Indonesia’s marine policy is lacking in consideration of the causes of vulnerability. It is also a common trend in ecosystem resource management to make fishing pressure is often the focus of conservation strategy, leaving out environmental effects [13]. Nevertheless, ecosystem stability results from climate influence [14] and interaction between different species [15]. As a part of preserving and protecting the marine environment, The Ministry of Marine Affairs and Fisheries has constructed a specific marine environment policy, to prevent, overcome, and recover the source of marine pollution and effect, potential marine disasters, and impacts from climate change. The purpose is to ensure that resources from the sea are readily available to use, enhance the quality of life, and establish a safer environment for all Indonesians, notably the coastal communities. Further, the possible impacts of global climate change is included, creating a national action plan for climate change adaptation, called RAN-API [16]. The objectives of RAN-API are to serve as a basis for mainstream climate change adaptation issues in the national development planning process, to act as a guide for short term, medium term, and long term action for sectoral and cross-sectoral plans for climate change adaptation, devising urgent short term priority actions so that it could get special attention, and to develop synchronised adaptation actions and efforts to build more effective communication and coordination systems for local government and sector [6]. This action plan is specifically developed for improving the systems resilience to the impacts of climate change, by various ministries, institutions, and using models by Intergovernmental Panel on Climate Change (IPCC) in order to predict the change in rainfall, surface temperature, sea surface temperature, and sea surface height. Some of its plans includes food diversification, enhancing aquaculture, and rehabilitation of degraded ecosystem.

Undoubtedley, RAN-API has proposed a progressive national action plan for increasing adaptive capacity on coastal communities. However, the interventions that are planned in the document would be more effective in tackling livelihood vulnerabilities if the proposed action are aligned with the state-of-the-art scientific knowledge. For instance, one of the action plans from RAN-API is to expand aquaculture sector [6] in order to reduce the risk of biodiversity loss due to climate change and fishing pressure. This effort is usually carried out near the coastal area. Unfortunately, Indonesian waters are not free from HAB organisms. For example Dinophysis, which cause nausea and diarrhoea to humans who consumed seafood infested with the phytoplankton, are found off the coast of Jakarta [17, 18, 9] and Pyrodinium, causative species of paralytic shellfish poisoning (PSP) in Ambon bay [19]. These locations are popular with aquaculture and tourism. Wild fish may swim away from the location of the bloom, however, trapped fish in aquaculture will suffer catastrophic mortality. The increase of HAB phenomenon might be caused by low level sewage treatment [20], and the increase in precipitation therefore increased levels of land runoff [21] resulting in eutrophication manifested by HAB. Therefore in devising a national action plan, understanding the mechanisms and pathways of how ecosystem response is essential [13]. It is generally acknowledged that there are significant gaps in understanding the marine ecosystem structures and functions and their response to human pressure [22, 23]. In order to evaluate its structure and function, and predict the impacts from human activities [24, 25, 26, 27, 28] and climate change [29, 30] on marine ecosystems, ecological models have been used and recognised as an effective method. Similar models have been used to provide information about indicators of good environmental status, such as biodiversity and food webs, in European Union’s Marine Strategy Framework Directive [31]. At the University of Reading, we are working on better understanding of marine biogeochemical processes by developing ecosystem models. The base of almost all marine food webs are the phytoplankton in the surface ocean and are also the bases of marine biogeochemical model. By combining information about physical forcing, chemical cycling, phytoplankton physiology, and ecological structure it is possible to simulate the response of phytoplankton to climate variability and change [32, 33, 34]. The timing of blooms [35] and differences in phytoplankton community structures [36] has long been recognised as a possible explanation for variations in the ecosystem over time and space [37]. From this realisation, phytoplankton are partitioned into distinct groups with common biogeochemical function. Same taxonomic size may have phytoplankton with different functional types, and the same phytoplankton taxonomic class may have divergent biogeochemical functions. Therefore, we separate phytoplankton into different functional groups in order to observe their variety of responses to environmental changes. Phytoplankton have different needs for different nutrients, some of them, such as the harmful dinoflagellates Pyrodinium prefer high salinities (30 – 35 PSU) and high temperatures (25⁰-28⁰C) [21]. Using these information along with physical forcings, it is possible to predict the timing of their blooms.

Furthermore, phytoplankton also have a socio-economic impact from commercial fisheries. In some countries, it has been shown that commercial fish stocks have been affected by the long-term changes in plankton communities. In the North Sea, in-spite of strong fishing pressure, during 1970s cods increased in abundance [38]. After analysis on plankton data, it revealed that the event coincide with a change in the dominant species of zooplankton in the North Sea, where larger zooplankton replaced smaller species during the time of development of cod larvae, making food readily available for larvae [38]. In contrast, the decline in phytoplankton productivity, due to the restriction of nutrient upwelling during El-Nin˜o event, provided less food for fish [39] resulting in the decline of commercial fisheries, such as anchovies [40]. This also means that the change in plankton communities could lead into a whole shift in the marine community [41]. Thus, developing a marine biogeochemical model with different plankton size and function is essential.

Although utilising models has been carried out by RAN-API to develop its plan, it is also beneficial to utilise biogeochemical models to predict the effect of human activities and climate change to the marine ecosystem. We aim to develop biogeochemical models including phytoplankton types, from which the ecosystem dynamics will be investigated using computer simulations and also in conjunction with the satellite remote-sensing based observations on global ocean. This approach will be effective in better understanding the formation of algal blooms (harmful and non-harmful), and eventually their impact on marine resources such as fisheries. The outcome of this study will potentially contribute to the management and climate adaptation strategies already initiated by the Indonesian Government.