High prevalence of diffusive uptake of CO2 by macroalgae in a temperate subtidal ecosystem
High prevalence of diffusive uptake of CO2 by macroalgae in a temperate subtidal ecosystem
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DOI：
10.1007/s11120-015-0114-0
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发表时间：
2015-05-01
影响因子：
3.7
通讯作者：
Hurd, Catriona L.
中科院分区：
文献类型：
--
作者：
Cornwall, Christopher E.;Revill, Andrew T.;Hurd, Catriona L.
目前认为大多数大型藻类的生产力不受溶解无机碳（DIC）的限制，因为大多数物种具有CO2浓缩机制（CCM），允许主动吸收DIC。另一种扩散吸收CO2（非CCM）被认为是罕见的（在给定的生态系统中占所有大型藻类覆盖的0- 9%），识别没有CCM的物种对于理解控制真核藻类使用无机碳的因素很重要。CCM活性比扩散CO2吸收具有更高的能量需求，因此当光照较低时，CCM活性降低，有利于扩散CO2吸收。我们假设，在澳大利亚南部塔斯马尼亚的四个地点，在两个深度（4-5米和12-14米），没有CCM的大型藻类（红色和绿色大型藻类）的覆盖比例较低（<10%）;缺乏CCM的物种比例将随着深度的减少而增加;具有CCM的大型藻类的C-13值将随着深度的增加而减少。我们发现非CCM物种的比例范围从0到90%，并且包括来自所有三个大型藻类门的物种：81%的红色（59个物种）、14%的棕色（三个物种）和29%的绿色大型藻类（两个物种）。非CCM物种的比例随深度增加，在四个网站。35%的测试物种在更深的深度具有显著耗尽的Δ C-13值。非CCM大型藻类在一些温带珊瑚礁中比以前认为的更丰富。如果海洋酸化有利于非CCM物种，潮线下大型藻类组合的影响可能比以前考虑的更大。
Productivity of most macroalgae is not currently considered limited by dissolved inorganic carbon (DIC), as the majority of species have CO2-concentrating mechanisms (CCM) allowing the active uptake of DIC. The alternative, diffusive uptake of CO2 (non-CCM), is considered rare (0-9 % of all macroalgal cover in a given ecosystem), and identifying species without CCMs is important in understanding factors controlling inorganic carbon use by eukaryotic algae. CCM activity has higher energetic requirements than diffusive CO2 uptake, therefore when light is low, CCM activity is reduced in favour of diffusive CO2 uptake. We hypothesized that the proportional cover of macroalgae without CCMs (red and green macroalgae) would be low (< 10 %) across four sites in Tasmania, southern Australia at two depths (4-5 and 12-14 m); the proportion of species lacking CCMs would increase with decreasing depth; the delta C-13 values of macroalgae with CCMs would be more depleted with depth. We found the proportion of non-CCM species ranged from 0 to 90 % and included species from all three macroalgal phyla: 81 % of red (59 species), 14 % of brown (three species) and 29 % of green macroalgae (two species). The proportion of non-CCM species increased with depth at three of four sites. 35 % of species tested had significantly depleted delta C-13 values at deeper depths. Non-CCM macroalgae are more abundant in some temperate reefs than previously thought. If ocean acidification benefits non-CCM species, the ramifications for subtidal macroalgal assemblages could be larger than previously considered.