Zardus John D
Department of Biology, The Citadel, 171 Moultrie Street, Charleston, SC 29409, USA.
Integr Org Biol. 2021 Feb 5;3(1):obab002. doi: 10.1093/iob/obab002. eCollection 2021.
Barnacles that are obligate epizoites of sea turtles are not parasites in the traditional sense. However, they can impair their hosts in some instances, disqualifying the association as strictly commensal. Characterizing these interactions requires knowing which epibionts pair with which hosts, but records of barnacles from sea turtles are scattered and symbiont/host match-ups remain equivocal. The objective of this study was to collate global records on the occurrence of barnacles with sea turtles and describe each species pair quantitatively. Records reporting barnacles with sea turtles were searched spanning the last 167 years, including grey literature, and findings were enumerated for 30,580 individual turtles to evaluate prevalence. The data were summarized globally as well as subdivided across six geographic regions to assess constancy of the affiliations. Patterns of partnering were visualized by hierarchical clustering analysis of percent occurrence values for each barnacle/turtle pair and the relative selectivity of each symbiont and susceptibility of each host were evaluated. After adjusting for synonymies and taxonomic inaccuracies, the occurrence of 16 nominal species of barnacles was recorded from all 7 extant sea turtle species. Mostly, barnacles were not specific to single turtle species, partnering on average with three hosts each. Neither were barnacles entirely host-consistent among regions. Three barnacles were common to all sea turtles except leatherbacks. The most common, widespread, and least selective barnacle was , the only symbiont of all turtles. Excluding single-record occurrences, the barnacle was the only single-host associate of any hard-shell sea turtle (the green sea turtle) and and were exclusive associates of leatherback sea turtles. Green sea turtles were the most vulnerable to epibiosis, hosting 13 barnacle species and Kemp's ridley sea turtles were the least, hosting three. Geographically, there was an average of nine barnacle species per world region, with diversity highest in the Pacific Ocean (12 species) and lowest in the Mediterranean Sea (6 species). It is paradoxical that the flexibility of barnacles for multiple host species contrasts with their overall strict specificity for sea turtles, with each symbiont occupying a virtually unique suite of turtle hosts.
海龟身上的专性体表共生藤壶并非传统意义上的寄生虫。然而，在某些情况下它们会对宿主造成损害，这使得这种共生关系不完全是共栖关系。要描述这些相互作用，需要了解哪些体表共生生物与哪些宿主配对，但海龟身上藤壶的记录分散，共生体/宿主的配对关系仍不明确。本研究的目的是整理全球关于海龟身上藤壶出现情况的记录，并定量描述每一对物种。搜索了过去167年里报告海龟身上有藤壶的记录，包括灰色文献，并对30580只个体海龟的调查结果进行了统计以评估其发生率。数据在全球范围内进行了汇总，并细分为六个地理区域以评估这种共生关系的稳定性。通过对每对藤壶/海龟出现百分比值进行层次聚类分析来直观呈现配对模式，并评估每个共生体的相对选择性和每个宿主的易感性。在对同义词和分类学不准确之处进行调整后，记录了所有7种现存海龟身上出现的16种名义上的藤壶物种。大多数情况下，藤壶并不特定于单一海龟物种，平均每种藤壶与三种宿主配对。藤壶在不同区域也并非完全与同一宿主共生。除棱皮龟外，有三种藤壶在所有海龟身上都很常见。最常见、分布最广且选择性最低的藤壶是 ，它是所有海龟唯一的共生体。排除仅有单条记录的情况，藤壶 是任何硬壳海龟（绿海龟）唯一的单宿主共生体，而 和 是棱皮龟的专属共生体。绿海龟最容易受到体表共生现象的影响，有13种藤壶寄生，而肯氏丽龟最少，有三种。从地理角度看，每个世界区域平均有9种藤壶物种，太平洋的多样性最高（12种），地中海最低（6种）。矛盾的是，藤壶对多种宿主物种具有灵活性，却又对海龟具有总体上严格的特异性，每种共生体占据着几乎独特的海龟宿主组合。
