Kornder Niklas A, Cappelletto Jose, Mueller Benjamin, Zalm Margaretha J L, Martinez Stephanie J, Vermeij Mark J A, Huisman Jef, de Goeij Jasper M
Department of Freshwater and Marine Ecology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, P.O. Box 94240, 1090 GE Amsterdam, The Netherlands.
Maritime Robotics Laboratory, Southampton Marine and Maritime Institute, Faculty of Engineering and Physical Science, University of Southampton, Southampton, SO16 7QF UK.
Coral Reefs. 2021;40(4):1137-1153. doi: 10.1007/s00338-021-02118-6. Epub 2021 Jun 16.
A paramount challenge in coral reef ecology is to estimate the abundance and composition of the communities residing in such complex ecosystems. Traditional 2D projected surface cover estimates neglect the 3D structure of reefs and reef organisms, overlook communities residing in cryptic reef habitats (e.g., overhangs, cavities), and thus may fail to represent biomass estimates needed to assess trophic ecology and reef function. Here, we surveyed the 3D surface cover, biovolume, and biomass (i.e., ash-free dry weight) of all major benthic taxa on 12 coral reef stations on the island of Curaçao (Southern Caribbean) using structure-from-motion photogrammetry, coral point counts, in situ measurements, and elemental analysis. We then compared our 3D benthic community estimates to corresponding estimates of traditional 2D projected surface cover to explore the differences in benthic community composition using different metrics. Overall, 2D cover was dominated (52 ± 2%, mean ± SE) by non-calcifying phototrophs (macroalgae, turf algae, benthic cyanobacterial mats), but their contribution to total reef biomass was minor (3.2 ± 0.6%). In contrast, coral cover (32 ± 2%) more closely resembled coral biomass (27 ± 6%). The relative contribution of erect organisms, such as gorgonians and massive sponges, to 2D cover was twofold and 11-fold lower, respectively, than their contribution to reef biomass. Cryptic surface area (3.3 ± 0.2 m m ) comprised half of the total reef substrate, rendering two thirds of coralline algae and almost all encrusting sponges (99.8%) undetected in traditional assessments. Yet, encrusting sponges dominated reef biomass (35 ± 18%). Based on our quantification of exposed and cryptic reef communities using different metrics, we suggest adjustments to current monitoring approaches and highlight ramifications for evaluating the ecological contributions of different taxa to overall reef function. To this end, our metric conversions can complement other benthic assessments to generate non-invasive estimates of the biovolume, biomass, and elemental composition (i.e., standing stocks of organic carbon and nitrogen) of Caribbean coral reef communities.
The online version contains supplementary material available at 10.1007/s00338-021-02118-6.
珊瑚礁生态学面临的一项重大挑战是估计存在于这种复杂生态系统中的群落的丰度和组成。传统的二维投影表面覆盖估计忽略了珊瑚礁和礁栖生物的三维结构，忽视了存在于隐秘礁栖生境（如悬垂处、洞穴）中的群落，因此可能无法代表评估营养生态学和礁功能所需的生物量估计。在这里，我们使用运动恢复结构摄影测量法、珊瑚点计数法、现场测量法和元素分析法，对库拉索岛（南加勒比海）12个珊瑚礁站点上所有主要底栖生物类群的三维表面覆盖、生物体积和生物量（即无灰干重）进行了调查。然后，我们将三维底栖生物群落估计值与传统二维投影表面覆盖的相应估计值进行比较，以使用不同指标探索底栖生物群落组成的差异。总体而言，二维覆盖以非钙化光合生物（大型藻类、草皮藻、底栖蓝藻席）为主（52±2%，平均值±标准误差），但它们对总礁生物量的贡献较小（3.2±0.6%）。相比之下，珊瑚覆盖（32±2%）与珊瑚生物量（27±6%）更为接近。柳珊瑚和块状海绵等直立生物对二维覆盖的相对贡献分别比它们对礁生物量的贡献低两倍和11倍。隐秘表面积（3.3±0.2平方米）占总礁基质的一半，使得在传统评估中三分之二的珊瑚藻和几乎所有的包被海绵（99.8%）未被检测到。然而，包被海绵在礁生物量中占主导地位（35±18%）。基于我们使用不同指标对暴露和隐秘礁群落的量化，我们建议对当前的监测方法进行调整，并强调评估不同类群对整体礁功能的生态贡献的影响。为此，我们的指标转换可以补充其他底栖生物评估，以生成加勒比珊瑚礁群落生物体积、生物量和元素组成（即有机碳和氮的现存储量）的非侵入性估计值。
在线版本包含可在10.1007/s00338-021-02118-6获取的补充材料。
