Lighting Effects on the Development and Diversity of Photosynthetic Biofilm Communities in Carlsbad Cavern, New Mexico
Lighting Effects on the Development and Diversity of Photosynthetic Biofilm Communities in Carlsbad Cavern, New Mexico
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DOI：
10.1128/aem.02695-20
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发表时间：
2021-03-01
影响因子：
4.4
通讯作者：
Jones, Daniel S.
中科院分区：
文献类型：
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作者：
Havlena, Zoe;Kieft, Thomas L.;Jones, Daniel S.
光合洞穴群落（“lampenflora”）在卡尔斯巴德洞穴和世界各地的其他洞穴中由于人工照明而激增。这些生物膜破坏了美学，并会降解洞穴表面。国家公园管理局最近将卡尔斯巴德洞穴的照明现代化为发光二极管（LED）系统，可以调整色温和强度。我们假设降低色温会减少色素的形成。因此，我们通过监测光合群落在一年的过程中，评估灯下植物对光照变化的反应。我们使用反射光分光光度法测量了色素，并使用16S和18S rRNA基因扩增子测序分析了微生物群落组成。反射光分光光度法表明，光合生物膜的发展受到光照强度，色温，基板类型，和清洁的基板。基因测序结果表明，最丰富的光养生物是蓝细菌和藻类门的成员绿藻和Ochrophyta。在研究结束时，在所有研究中心均观察到明显的灯花生长。在研究期开始时没有建立生物膜的地点，蓝细菌变得丰富，并且超过了真核藻类的增加。微生物多样性也随着时间的推移在这些网站上增加，这表明早期殖民和继承的可能模式。细菌群落结构表现出显着的影响，所有变量：色温，光照强度，基板类型，网站，和以前的清洁基板。这些发现提供了基本的信息，可以告知管理措施，他们认为，改变光照条件单独可能不足以防止lampenflora的增长。重要性在游客参观的洞穴（“显示洞穴”）人工照明可以刺激光合藻类和蓝藻，称为“lampenflora”，这是不雅观的，破坏洞穴和其他洞穴表面。最常见的缓解策略是使用漂白剂，但改变光线的强度和波长可能是有效的，也不那么苛刻。位于新墨西哥州的卡尔斯巴德洞穴是美国国家公园和联合国教科文组织世界遗产，尽管调整了LED灯以减少充满活力的蓝光，但仍有可见的灯光植物。本研究主要探讨了光照强度、颜色温度、岩石或沉积物质地、时间等因素对七鳃鳗群落发育的影响。DNA扩增子序列数据显示了多种藻类和蓝藻以及异养细菌。这项研究揭示了人工照明表面定植过程中的微生物动力学，并表明虽然降低色温可能会产生影响，但对lampenflora的管理可能需要额外的化学或紫外线处理。
Photosynthetic cave communities ("lampenflora") proliferate in Carlsbad Cavern and other show caves worldwide due to artificial lighting. These biofilms mar the esthetics and can degrade underlying cave surfaces. The National Park Service recently modernized the lighting in Carlsbad Cavern to a light-emitting diode (LED) system that allows adjustment of the color temperature and intensity. We hypothesized that lowering the color temperature would reduce photopigment development. We therefore assessed lampenflora responses to changes in lighting by monitoring photosynthetic communities over the course of a year. We measured photopigments using reflected-light spectrophotometric observations and analyzed microbial community composition with 16S and 18S rRNA gene amplicon sequencing. Reflected-light spectrophotometry revealed that photosynthetic biofilm development is affected by lighting intensity, color temperature, substrate type, and cleaning of the substrate. Gene sequencing showed that the most abundant phototrophs were Cyanobacteria and members of the algal phyla Chlorophyta and Ochrophyta. At the end of the study, visible growth of lampenflora was seen at all sites. At sites that had no established biofilm at the start of the study period, Cyanobacteria became abundant and outpaced an increase in eukaryotic algae. Microbial diversity also increased over time at these sites, suggesting a possible pattern of early colonization and succession. Bacterial community structure showed significant effects of all variables: color temperature, light intensity, substrate type, site, and previous cleaning of the substrate. These findings provide fundamental information that can inform management practices; they suggest that altering lighting conditions alone may be insufficient to prevent lampenflora growth.IMPORTANCE Artificial lighting in caves visited by tourists ("show caves") can stimulate photosynthetic algae and cyanobacteria, called "lampenflora," which are unsightly and damage speleothems and other cave surfaces. The most common mitigation strategy employs bleach, but altering intensities and wavelengths of light might be effective and less harsh. Carlsbad Cavern in New Mexico, a U.S. National Park and UNESCO World Heritage Site, has visible lampenflora despite adjustment of LED lamps to decrease the energetic blue light. This study characterized the lampenflora communities and tested the effects of color temperature, light intensity, rock or sediment texture, and time on lampenflora development. DNA amplicon sequence data show a variety of algae and cyanobacteria and also heterotrophic bacteria. This study reveals microbial dynamics during colonization of artificially lit surfaces and indicates that while lowering the color temperature may have an effect, management of lampenflora will likely require additional chemical or UV treatment.