为什么珊瑚岛热点存在于大洋沙漠

生产力热点在原本贫瘠的海洋。 在一个印度洋 - 太平洋珊瑚礁浮游生物为食的鱼类高丰度。 扎菲尔Kizilkaya,CC BY-SA生产力热点在原本贫瘠的海洋。 在一个印度洋 - 太平洋珊瑚礁浮游生物为食的鱼类高丰度。 扎菲尔Kizilkaya,CC BY-SA

这是 查尔斯·达尔文几乎200年前,谁首先问这怎么可能,珊瑚礁可能会蓬勃发展太平洋的比较瘠薄的地方。 这个难题后来被称为达尔文的悖论。

在本周发表的一项研究 自然通讯 有助于回答在海洋沙漠多么珊瑚绿洲可以存在。

简单的解释是被称为浮游植物的微小水生植物的存在。 更复杂的,科学的答案 - 这问为什么珊瑚岛是这样生产的热点 - 被称为岛质量效应(IME)。

新的研究结果提供了谁研究海洋渔业和栖息地具有重要的见解岛系统如何珊瑚礁能够如此高效,作为物种多样性的热点地区,这反过来,有利于填充渔业和沿海提供保护的科学家。 这些知识可以帮助告知海洋管理计划,特别是生态系统对气候变化的响应。珊瑚reef2 2 29从发表在Nature这项新的研究中岛质量效应的插图。

海岛质量效应(IME)

该输入法, 首先描述 夏威夷大学的植物学家麦克斯韦S.多蒂和他的同事,是一种现象,其中浮游植物的生长增强接近岛珊瑚礁生态系统。

Until now, all studies trying to explain the reasons for the IME have been done over small, geographically confined areas, such as a single island or coral reef group.

This is where the 自然通讯 paper’s lead author, Jamison Gove of the National Oceanic and Atmospheric Administration (NOAA), and his colleagues come in.

Their new study is the first to describe the IME over the scale of an entire ocean and discusses the role of both natural and human island populations on phytoplankton growth.

The team measured just how much phytoplankton grew around small islands and atolls in two ways. They used satellite imagery over a decade and direct ship-based surveys to verify that their image estimates were correct.

The IME was found to be near-ubiquitous, with 91 percent of the coral ecosystems studied demonstrating the phenomenon, some showing as much as 86 percent more phytoplankton biomass compared to neighboring ocean areas.

In other words, phytoplankton coral island hotspots surrounded by barren oceans landscapes were nearly everywhere the team looked.

The higher rate of phytoplankton growth around the coral islands is caused by nutrients that result from decomposing reef animals, upwellings of nutrient-rich colder waters toward the surface, the mixing effects of waves and currents, and sedimentation from land erosion. There are also human-derived runoffs from agriculture, urban development and wastewater inputs, which all add nutrients to coastal waters.

Who cares about the IME or Darwin’s Paradox?

Microscopic phytoplankton play an outsize role in ocean life.

By converting the sun’s energy into plant growth, they are an essential component in our oceans and drive the structure of food webs and ultimately global fisheries yields. More phytoplankton also means more energy-rich resources for important reef building organisms that determine the architecture of tropical coral reefs, which provide protection for neighboring coastlines.

Southern Line Islands. High productivity means more coral growth and cover offering coastal protection to island nations and increased biodiversity and abundance. Brian Zgliczynski - Scripps Institution of Oceanography, San Diego, CaliforniaSouthern Line Islands. High productivity means more coral growth and cover offering coastal protection to island nations and increased biodiversity and abundance. Brian Zgliczynski - Scripps Institution of Oceanography, San Diego, CaliforniaIncreased levels of phytoplankton are, however, not always good news. Extreme levels of nutrient enrichment from runoff related to agriculture and other human activities have been shown to increase phytoplankton biomass to levels that can cause sea population structures to change entirely. High levels of nutrients have also led to mass mortalities of more sensitive, yet important species along with the suppression of reef growth.

By better understanding the role of the IME and its impacts on fisheries as well as the negative effects of high human-derived nutrient enrichment, island nations can focus marine conservation efforts on ensuring they do not overload local reef systems past such tipping points.

The future of coral islands

Climate change is predicted to raise ocean temperatures, which will lower lower ocean productivity by changing the way our oceans cycle and mix around the planet. The IME will therefore be an ever important phenomenon to understand as we develop plans to support coral reef ecosystems in the future to avoid stresses from warmer waters.

To sustainably exploit tropical fisheries and continue to rely on coral reefs to protect nearshore human populations, research should focus on understanding the processes that make coral islands and atolls hotspots of productivity. We must dive deeper into questions Darwin was asking some 180 years ago while applying them to today’s global oceans and predicted future change.

Booming productivity at Palmyra Atoll, central Pacific the Island Mass Effect bringing huge fisheries rewards to an otherwise empty ocean. Gareth J Williams, School of Ocean Sciences, Bangor University, UKBooming productivity at Palmyra Atoll, central Pacific the Island Mass Effect bringing huge fisheries rewards to an otherwise empty ocean. Gareth J Williams, School of Ocean Sciences, Bangor University, UK

关于作者

johnson andrewAndrew Frederick Johnson, Postdoctoral Researcher of Marine Biology at Scripps Insitution of Oceanography, University of California, San Diego. research focuses on the impacts of marine fisheries on fish populations and habitats. Since beginning his studies in marine biology in 2002, he has traveled extensively, working with nine different fisheries in six countries gaining valuable experience in a range of fishing methods and management strategies.

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