a)　　The objective of the project is to elucidate the role of the Amur River in primary productivity in the Sea of Okhotsk and Oyashio region and then evaluate possible human impacts such as land surface disturbances in the Amur River basin on the marine ecosystem of the ocean. In this study, we attempt to answer 1) how dissolved iron is transported from the Amur River basin to the Sea of Okhotsk and Oyashio region, 2) to what extent the supply of dissolved iron regulates the primary production in these open waters, 3) how the land surface disturbances affect the material circulation in the Amur–Okhotsk system, 4) how human activity will impact the system in the future, and 5) how we can conserve this transboundary system. By answering these five questions, we will be able to propose a new global environmental concept, the “giant” fish-breeding forest (GFBF), in which there are physical and humanistic interactions between upstream and downstream, and determine a way of conserving the system in a cooperative effort among China, Russia, Mongolia and Japan.

　　The Amur–Okhotsk Project attempts to create a new global environmental concept, referred to as the GFBF, by expanding the traditional Japanese idea of Uotsuki-Rin (fish-breeding forest). This idea relates the upstream forest with the coastal ecosystem both physically and conceptually. The GFBF and its impacted area encompass nearly 4 million km². This includes parts of Mongolia, China and Russia as well as Russian and Japanese exclusive economic zones and international waters. The area has been the source of extreme political tension since the middle of the 19th century and there has been little transboundary cooperation. This situation has resulted in the Amur River becoming one of the most seriously polluted waters in Russia.

　　The GFBF hypothesis presents new perspectives for global environmental issues: an ecological linkage between the continent and open sea, the relating of less-dependent stakeholders in the system, and finding environmental common ground across complex international boundaries. Multidisciplinary approaches are indispensable in studying and conserving the GFBF because stakeholders need to understand how to achieve a sustainable marine ecosystem in the Sea of Okhotsk and Oyashio region without limiting human activity on land.

　　We believe the GFBF can be a test bed for global environmental problems in general. Connecting less-dependent stakeholders could be a first step in coping with complicated environmental issues. We attempt to visualize socio-economic relationships within the GFBF system to demonstrate how stakeholders are related to each other unconsciously. Establishment of the concept will help bring together societies that have been separated for many years by political tension.

 

b)　　The physical structure of the GFBF was jointly studied by collaborators in the fields of biogeochemistry, geography, hydrology, climatology, glaciology and oceanography. The economic flow, land-use background, and conservation strategies of the system were studied by scientists in the fields of forest management, agronomy, economic geography, international law and politics.

　　This project comprises 10 research groups headed by group leaders (GLs). The project leader and 10 group leaders constitute the board of the project. In addition to individual group meetings, at least one project meeting has been held each year to discuss cross-disciplinary issues. Daily communications and discussion have been carried out through an Internet mailing list. The themes/tasks of each research group are as follows. Group 1 (GL: Dr. Kay I Ohshima): physical oceanographic conditions of the Sea of Okhotsk and the northern North Pacific; Group 2 (GL: Dr. Takeshi Nakatsuka): geochemical and biological conditions of the Sea of Okhotsk and the northern North Pacific; Group 3 (GL: Dr. Seiya Nagao): transport of biogeochemical materials from the Amur River to the Sea of Okhotsk; Group 4 (GL: Dr. Hideaki Shibata): biogeochemical transportation from the terrestrial ecosystem to the Amur River; Group 5 (GL: Dr. Hiroaki Kakizawa): background of anthropogenic impacts in the Amur River basin; Group 6 (GL: Dr. Shigeko Haruyama): spatial and historical monitoring of land-use changes in the Amur River basin; Group 7 (GL: Dr. Sumito Matoba): estimation of the atmospheric transportation of terrestrial material; Group 8 (GL: Dr. Takeo Onishi): numerical modelling of basin-scale hydrology and iron transportation; Group 9 (GLs: Drs. Hiroyuki Matsuda and Fumio Mitsudera): numerical modelling of primary production in the Sea of Okhotsk and the northern North Pacific; Group 10 (GL: Mr. Yasunori Hanamatsu): conservation strategy for the GFBF.

 

c) 　　　Three major achievements have been made in the Amur Okhotsk Project.

1. Iron-bound material and ecological linkages from the Amur River basin to the Oyashio region via the Sea of Okhotsk were finally quantified by 1) observations of the spatiotemporal distribution of dissolved iron in various parts of the Amur River basin, 2) monthly monitoring of dissolved iron concentrations and discharges at Khabarovsk and Bogorodskoe, 3) observations of the temporal distributions of dissolved iron in the lower reach, mouth, and estuarial area of the Amur River, 4) measurements of dissolved iron in the Sea of Okhotsk and Oyashio region, and 5) measurements of the atmospheric iron input to the Oyashio region. It was found that approximately 40% of the dissolved iron necessary to support phytoplankton production in the Oyashio region was transported through the GFBF system. The remaining 60% was microbially recycled iron originally provided by intermediate water and atmospheric input.

 

2. It was found that there are two current threats to the GFBF system: global warming and human impacts on land surfaces. The former is most clearly indicated by the decreasing trend of sea ice production in the Sea of Okhotsk in recent decades and its impact on the ocean and material circulation in the northern North Pacific. The latter is illustrated by the decreasing trend of iron discharge from the Amur River basin to the Sea of Okhotsk due mainly to the reclamation of wetland to form paddy fields and dry land.

 

3. The Amur Okhotsk Consortium was established in 2009 as a multinational academic network to discuss the conservation and sustainable use of the GFBF. Japanese, Chinese and Russian members will hold a joint meeting every two years and exchange ideas, information and data routinely via the Internet between meetings.

Major achievements of the Amur Okhotsk Project (2005–2009) are described by answering the five essential questions of the project.

 

1) How is dissolved iron transported from the Amur River basin to the Sea of Okhotsk and Oyashio region?

　　Average annual fluxes of total and dissolved iron were estimated in various parts of the GFBF and they confirmed the continuity of iron transportation from the land surfaces of the Amur River basin to the surface water of the Oyashio region (Fig. 1). The natural wetlands with gentle slope located at middle and lower part of Amur basin was major source of dissolved iron from terrestrial zone to Amur river.

　　In the upstream forested basin, dissolved iron in soil was mainly transported with dissolved organic carbon (DOC) rather than as Fe(II) and Fe(III). The riparian zone near the stream channel is an important source of iron owing to its wet and anaerobic condition increasing the DOC concentration and dissolving iron in soil and groundwater.

　　In the natural wetlands, the dissolved Fe concentration is around 1 mg Fe L^–1 in the surface water and much higher (sometimes more than 10 mg Fe L^–1) in soil interstitial waters, having a seasonal variation with maxima in summer. The dissolved Fe concentration observed for a number of rivers and agricultural drainage waters of the Sanjiang plain when not frozen has an average of approximately 1 mg Fe L^–1 and varies considerably according to the condition of the watershed. Dissolved Fe is dominantly present as complexed forms in soil water, river water and agricultural drainage water, in which humic substances play an important role in the transportation of iron as a complex ligand.

　　As a result, 1.1 ± 0.7 x 10¹¹ g/yr of dissolved iron is transported to the estuarial area from the Amur River annually. Approximately 95% of the dissolved iron coagulates at Amur–Liman (the estuarial area) and Sakhalin Bay. There are two pathways of iron transportation from the estuarial area to the Oyashio region: 1) surface transportation of total iron and 2) transportation with the North Pacific Intermediate Water (NPIW). The former supports primary production in the Sea of Okhotsk while the latter supports primary production in the Oyashio region. It is estimated that approximately 1.2–1.5 x 10⁸ g/yr of total iron is provided by the atmosphere and NPIW in the Oyashio region.

 

2) To what extent does the supply of dissolved iron regulate primary production in the open waters?

　　It was found that of the iron used by the spring bloom in the Oyashio region, 40% is provided through the GFBF system and 60% is recycled through microbial processes. We are not yet certain about the relative importance of atmospherically derived iron to primary production in the Oyashio region because of its temporal sporadicity, spatial unevenness and insoluble nature. In spite of this uncertainty, it is reasonably concluded that the iron controls phytoplankton growth in the Oyashio region because phytoplankton growth ceases under iron limitation at all high nitrate concentrations.

　　It is yet uncertain to what extent the supply of dissolved iron regulates primary production in the open waters. This is due mainly to a lack of sufficient observational data on both annual changes in the dissolved iron flux and the biomass in the Oyashio region. To determine the role of the dissolved iron, we used a three-dimensional

coupled ecosystem physical model that includes the effect of iron on the Sea of Okhotsk. We hypothesized that four processes supply iron to sea water: atmospheric loading, input from the Amur River, dissolution from sediments and regeneration by zooplankton and bacteria. We simulated one year, from 1 January 2001 to 31 December 2001. As a result, the model taking iron into account agreed well with the observation. However, we are not yet able to simulate the time series of the iron impact, since the model cannot simulate the NPIW, which we believe is the most important current in the transportation of riverine iron from the Amur River.

 

3) How do land surface disturbances affect material circulation in the Amur–Okhotsk system?

　　The impact of land-use change on iron discharge was studied in experimental plots of upland fields and paddy fields on the Sanjiang plain, which were converted from natural wetlands several decades ago (Fig. 2). Soil in the upland fields was found to remain in an oxidized condition throughout the year, implying the absence of iron discharge. In paddy fields, surface water and soil water had dissolved Fe concentrations somewhat lower than those of natural wetlands, but importantly, the controlled water discharge due to agricultural management is considered to largely lower the iron discharge.

　　Paddy fields on the Sanjiang plain are irrigated with ground water in most cases. The strikingly high concentration of dissolved iron (largely in the form of Fe²⁺) might indicate an additional iron source. However, elevated contents of amorphous iron oxides in the upper soil layer in paddy fields were found to adequately account for the calculated total amount of iron supplied by the irrigation of ground water since the rice paddy conversion on the Sanjiang plain, suggesting an almost complete retention of iron added by the ground water. Considering the irrigation and the controlled water discharge described above, it is concluded that iron discharge may be much less for paddy fields than for natural wetlands.

　　Monitoring data indicate that the concentration of dissolved iron in the Naoli River, which runs across the Sanjiang plain, has been consistently decreasing in recent decades. The observation of a peat layer, except in hilly areas, suggests a predominance of wetlands on the Sanjiang plain in the pristine age. However, a survey of the ground water table demonstrated that the current ground water levels were greatly lowered in most regions owing to reclamation by water drainage. It is likely that the land previously dominated by wetlands has been becoming steadily drier on the Sanjiang plain, which has reduced the Fe discharge as mentioned above.

　　Land-use and historical changes in the Amur River basin were visualized by various temporal and spatial mappings. We compiled land-use maps for both the 1930s and 2000 for the whole Amur River basin. Changes in the most recent 19 years were analyzed using Pathfinder AVHRR Land datasets and satellite remote-sensing techniques. The results show significant changes on the Sanjiang plain in which approximately 10,000 km² of wetland was reclaimed as paddy fields from 1980 to 2000. Aerial changes of Russian forest were not significant but the quality of the forest is considered to be deteriorating mainly owing to frequent forest fires and poor management.

　　Such land-use changes were caused by various factors. According to analyses of the underlying causes of the degradation of forest resources in Khabarovsk Krai and systems are identified as the major causes of forest degradation. The rapid increase in timber exports to China and poor forest policy are considered to accelerate forest degradation. On the Sanjiang plain, there was rapid development of paddy fields in accordance with governmental policy. Farm management has improved, but a lack of water has become a serious issue and the excessive pumping of ground water has caused the rapid lowering of the ground water table on the Sanjiang plain.

 

4) How will human activity impact the system in the future?

　　We attempted to develop a numerical hydro-geochemical model with special emphasis on iron dynamics for the Amur River basin. The accuracy of the calculated discharge and dissolved iron concentration are sufficient at a time resolution of one month during the period from 1980 to 1990. Using the model, the effect of land cover change on dissolved iron productivity was evaluated. The results of numerical experiments suggest that 50% conversion of remaining wetlands to agricultural lands might decrease the dissolved iron flux by more than 10% (Fig. 3).

 

5) How can we conserve this transboundary system?

　　The key problem in conservation is how to establish a multilateral cooperative framework for the GFBF system. There have already been some bilateral frameworks, including the formal joint-monitoring program between China and Russia after the Songhua River accident involving a petrochemical company in the Chinese province of Jiling in 2005, and the cooperative program on the research, conservation and sustainable use of the ecosystems in the Sea of Okhotsk signed by Russia and Japan in 2009. However, there has been no multilateral governmental framework concerning the GFBF system. At this stage, joint-monitoring, data exchange and mutual

communication at an academic level are necessary as a starting point for the protection of the GFBF system. For this purpose, we established the Amur Okhotsk Consortium as a multinational academic network to discuss the conservation and sustainable use of

the GFBF (Fig. 4). The network can be thought of as comprising “epistemic communities”; Peter Haas proposed that such networks of knowledge-based experts could help states identify their interests, frame issues for collective debate, propose specific policies, and identify salient points for negotiations. Our attempt is motivated by the history of the environmental protection of the Baltic Sea from marine pollution for over 30 years.

　　On the other hand, we have analysed existing international and domestic laws and policies that seem to be applicable for the conservation of the GFBF system. A future conservation framework would incorporate them as useful components. The results

show that while environmental factors in GFBF have already been partially regulated by international and national laws and policies, these management regimes have been established and implemented independently, and they sometimes overlap or conflict; therefore, they are not appropriate for the conservation of the whole GFBF system. We conclude that it is important to coordinate and strengthen existing laws and policies in an integrated manner to manage this system consistently and effectively (Fig. 5).