Quantitative imaging to measure photosynthetic biomass on an intertidal rock-platform
Quantitative imaging to measure photosynthetic biomass on an intertidal rock-platform
复制标题
定量成像测量潮间带岩石平台上的光合生物量
DOI：
10.3354/meps312045
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发表时间：
2006
影响因子：
2.5
通讯作者：
M. Pinkerton
中科院分区：
文献类型：
--
作者：
R. Murphy;A. Underwood;M. Pinkerton
通过估算岩石样品中叶绿素的含量来测量潮间带生境中附着生物光合生物量的传统方法是不精确、费力和具有破坏性的。提出了一种利用基于场的数字彩色红外（CIR）图像在小尺度上定量叶绿素含量的替代遥感方法。从4个区域获得了出露岩石平台的CIR图像。首先刮除试验田，去除任何大型或微型藻类。在不同时期的微藻再定殖后，在完全阳光下或人工遮荫下，在均匀润湿岩石之前和之后，获得样地的图像。取岩石样品进行室内叶绿素含量测定。利用近红外（NIR）波段和红光波段的比值，估算了叶绿素的相对吸收。通过与现场光谱仪的数据进行比较，验证了图像比率。从岩石样品中提取的叶绿素量的测量值与近红外：红比值的估计值呈线性相关。在充分光照下、湿润地表之前和之后获得的图像的比值与叶绿素的关系最强（r2分别= 0.84和0.83）。岩石的人工遮荫降低了润湿前后叶绿素与NIR:red比值的关系强度（r2分别为0.79和0.63）。使用相同的公式可以估计刮削区域的微藻和微、大藻混合物。该技术可以在不破坏微生物群的情况下对叶绿素进行快速连续的原位测量，并将促进对潮间带放牧动物之间竞争相互作用的更全面的研究。
Conventional methods for measuring amounts of epilithic photosynthetic biomass in intertidal habitats by estimating amounts of chlorophyll in rock samples are imprecise, laborious and destructive. An alternative remote sensing method for quantifying chlorophyll amounts at small spa- tial scales using field-based digital colour-infrared (CIR) imagery is presented. CIR images were obtained from 4 areas of the emersed rock-platform. Experimental plots were initially scraped to remove any macro- or micro-algae. After different periods of recolonization of micro-algae, images of the plots were acquired under full sunlight or under artificial shade, before and after the rocks were uniformly wetted. Samples of rock were taken for laboratory determination of amount of chlorophyll. Relative absorption by chlorophyll was estimated from CIR data using a ratio of near-infrared (NIR) and red bands. The image ratios were validated by comparing them to data from a field spectrome- ter. Measurements of the amount of chlorophyll extracted from rock samples were linearly related to estimates from the NIR:red ratio. Ratios derived from images acquired under full sunlight, before and after wetting the surface, had the strongest relationship with chlorophyll (r 2 = 0.84 and 0.83, respec- tively). Artificial shading of the rock reduced the strength of the relationship between chlorophyll and the NIR:red ratio before and after wetting (r 2 = 0.79 and 0.63, respectively). Micro-algae in scraped areas and micro- and macro-algal mixtures could be estimated using the same equation. The technique enables rapid contiguous in situ measurements of chlorophyll to be made without the microflora being destroyed and will facilitate more comprehensive studies of competitive interactions among intertidal grazing animals.