Meise Botanic Garden, Research Department, Meise, Belgium.
Department of Biology-ECOBE, University of Antwerp, Antwerpen, Belgium.
PLoS One. 2020 Jul 29;15(7):e0236513. doi: 10.1371/journal.pone.0236513. eCollection 2020.
Epizoic diatoms form an important part of micro-epibiota of marine vertebrates such as whales and sea turtles. The present study explores and compares the diversity and biogeography of diatom communities growing on the skin and shell of loggerhead sea turtles (Caretta caretta) from four different localities: Adriatic Sea (Croatia), Ionian Sea (Greece), South Africa and Florida Bay (USA) using both light and scanning electron microscopy. We observed almost 400 diatom taxa belonging to more than 100 genera. Diatom communities from Greece and Croatia showed the highest similarity and were statistically different from those recorded from South Africa and Florida. Part of this variation could be attributed to differences in sampling techniques; however, we believe that geography had an important role. In general, contrary to several previous observations from sea turtles, the presumably exclusively epizoic diatoms contributed less than common benthic taxa to the total diatom flora, which might have been related to the loggerhead feeding behavior. Moreover, skin samples differed from carapace samples in having a distinct diatom composition with a higher proportion of the putative true epizoonts. Our results indicate that epizoic diatom communities differ according to loggerhead geographical location and substrate (skin vs. carapace). The relative abundances of common benthic diatoms and putative exclusive epizoic taxa may inform about sea turtle habitat use or behavior though detailed comparisons among different host species have yet to be performed.
附生硅藻是海洋脊椎动物（如鲸鱼和海龟）的微型外生物群的重要组成部分。本研究使用光学和扫描电子显微镜，探索和比较了来自四个不同地点（亚得里亚海（克罗地亚）、爱奥尼亚海（希腊）、南非和佛罗里达湾（美国））的生活在红海龟（Caretta caretta）皮肤和壳上的硅藻群落的多样性和生物地理学。我们观察到近 400 种属于 100 多个属的硅藻。希腊和克罗地亚的硅藻群落具有最高的相似性，并且与南非和佛罗里达的记录有统计学差异。这种变化的部分原因可能归因于采样技术的差异；但是，我们认为地理位置也起到了重要作用。与之前从海龟中观察到的几种情况相反，假定的纯粹附生硅藻对总硅藻植物群的贡献小于常见的底栖类群，这可能与红海龟的摄食行为有关。此外，与龟壳样本相比，皮肤样本的硅藻组成明显不同，假定的真正附生物的比例更高。我们的研究结果表明，附生硅藻群落因红海龟的地理位置和基质（皮肤与龟壳）而异。常见底栖硅藻和假定的专性附生类群的相对丰度可能反映了海龟的栖息地利用或行为，尽管还需要对不同的宿主物种进行详细比较。
