School of Geography and Geology, McMaster University, N0G 1R0, Canada..
Institute of Geophysics, University of Tehran, North Kargar Ave., Tehran 1439955961, Iran.
Mar Pollut Bull. 2021 May;166:112079. doi: 10.1016/j.marpolbul.2021.112079. Epub 2021 Mar 19.
Around the world, coral reefs are in decline. Recent interest has focussed on the impacts of global warming/climate change, but the decline started long before the influence of climate change became apparent, driven by anthropogenic factors such as sedimentation, nutrient increase, and overfishing. These continue with no real signs of abatement, as does concomitant reef damage. The Persian Gulf supports widespread coral growth, especially on the Iranian side. Responding to issues of food security, the Iranian government has proposed large-scale aquaculture (open-net fish pens) along their coastline, with an eventual production of 200,000 t/year. Nutrient discharge will be a major issue. We developed a hydrodynamic circulation model for the Persian Gulf which allows us to follow the path of dissolved material. We estimated the amount of nitrogen that would be produced by the projected farms and modelled nitrogen distribution over time, using production rates of 44kgN released/t of fish. In a model run simulating one year at full operation of the proposed number of fish farms, we estimate that most of the reefs on the Iranian side will be bathed in waters with nutrient levels higher than will allow for reef survival. We used a trigger value of 20 μg/l total N. Mangroves will also be affected. There is significant trans-border movement of nutrients, to the waters of neighbouring countries. In fact, withing a few years the entire Gulf will be affected. These planned aquaculture projects have the potential to damage the mangroves and kill every reef in the Persian Gulf in a very short period of time. There is a high probability of affecting fisheries resources in neighbouring countries-a situation to be avoided in politically volatile regions. There seem only two solutions: 1. either run the fish farms so that nutrient discharge is kept to acceptable levels, using an ironclad monitoring system, or 2. bring the operations on land by establishing recirculating aquaculture systems.
世界各地的珊瑚礁都在减少。最近的研究重点集中在全球变暖/气候变化的影响上，但珊瑚礁的减少早在气候变化的影响明显之前就开始了，其驱动因素是人为因素，如沉积物、营养物增加和过度捕捞。这些因素仍在继续，没有明显的缓解迹象，珊瑚礁也随之受到破坏。波斯湾支持广泛的珊瑚生长，特别是在伊朗一侧。为了应对粮食安全问题，伊朗政府沿其海岸线提出了大规模水产养殖（开放式网箱养鱼）计划，最终目标是每年生产 20 万吨。营养物质的排放将是一个主要问题。我们为波斯湾开发了一个水动力循环模型，使我们能够跟踪溶解物质的路径。我们根据预计的养殖场的产量，使用 44kgN/吨鱼的释放率，估计了氮的产生量，并对氮的分布进行了时间建模。在模拟拟议的养殖场数量全部投入运行一年的模型运行中，我们估计伊朗一侧的大多数珊瑚礁将处于营养水平高于允许珊瑚礁生存的水平的水域中。我们使用 20μg/l 总氮的触发值。红树林也将受到影响。营养物质有大量跨境迁移，进入邻国的水域。事实上，在短短几年内，整个海湾都将受到影响。这些计划中的水产养殖项目有可能破坏红树林，并在很短的时间内杀死波斯湾的所有珊瑚礁。有很大的可能性会影响邻国的渔业资源——在政治不稳定的地区，这种情况是需要避免的。似乎只有两种解决方案：1. 或者通过建立严格的监测系统，将养殖场的营养物质排放量控制在可接受的水平，或者 2. 通过在陆地上建立循环水产养殖系统来进行养殖。
