For Better, For Worse: Manatee‐Associated Tursiocola (Bacillariophyta) Remain Faithful to Their Host

Abstract

With the advent of more comprehensive research into the microbiome and interactions between animals and their microbiota, new solutions can be applied to address conservation challenges such as husbandry and medical care of captive animals. Although studies on epizoic algae are relatively rare, and the function and role of those mainly photosynthetic organisms in the animal microbiome is not well understood, recent surveys on epizoic diatoms show that some of them exhibit traits of obligate epibionts. This study explores diatom communities on captive–born manatees from the Africarium in Wroclaw, Poland. Light and scanning electron microscopy analyses revealed that skin of all animals sampled was dominated by apochlorotic Tursiocola cf. ziemanii, an epizoic species described recently from Florida manatees, that reached 99,9% of the total diatom abundance. Despite using media with a wide range of salinity (0–34), the isolated Tursiocola cells did not grow, whereas the normally pigmented Planothidium sp., that was only occasionally found on the animal substratum, survived in all culture media tested. Our observations provide direct evidence that manatee–associated Tursiocola endure the dramatic salinity changes that occur regularly during their host life cycle, and can thrive in an artificial captive setting, if the manatee substratum is available. The impact of practices and routines used by the Africarium on manatee–associated diatoms, as well as ultrastructure of areolae in Tursiocola, are briefly discussed.

DNA Sequence Analyses Reveal Two New Species of Caloglossa (Delesseriaceae, Rhodophyta) from the Skin of West Indian Manatees

“…Manatees migrate between fresh and marine waters [11]; therefore, persistent epizoic algal species must be able to tolerate a wide range in salinity. Majewska and Goosen [15] hypothesized that putative obligately-epizoic diatoms are limited more by the availability of the animal substratum rather than any of the abiotic environmental factors. Tursiocola ziemanii, an abundant diatom on manatee skin often reaching near 100% relative cell abundance, has been observed to numerically dominate the diatom skin flora on manatees from fresh [15] and marine waters [8], and on the manatees sampled during this study.…”

“…Majewska and Goosen [15] hypothesized that putative obligately-epizoic diatoms are limited more by the availability of the animal substratum rather than any of the abiotic environmental factors. Tursiocola ziemanii, an abundant diatom on manatee skin often reaching near 100% relative cell abundance, has been observed to numerically dominate the diatom skin flora on manatees from fresh [15] and marine waters [8], and on the manatees sampled during this study. The epizoic diatoms that are dominant on cetaceans, sea turtles, and manatees belong to species and often genera that are exclusive to the epizoic habit [5,6,8,9], and therefore, whether they are considered freshwater, brackish, or marine diatoms, is dependent on the habitat of the host animal.…”

“…They have limited cold tolerance [10] and may migrate seasonally between fresh and marine habitats [11]. While cetaceans and pinnipeds have anti-microbial mechanisms [12] and many cetaceans have smooth skin to inhibit fouling by epibionts [13], West Indian manatees do not seem to have evolved similar defenses [14], although, their skin exfoliates after shifting between salt-and freshwater, which may help to reduce biofouling [15].…”

Culturing Putatively Obligate Epizoic Diatoms: Insights for the Evolution and Ecology of Diatoms and Their Host

“…Host behavior may also in uence settlement. West Indian manatees, for example, move from marine to brackish to freshwater habitats in response to seasonality and water temperature, potentially at a rate and duration to which opportunistic diatoms may not be able to adapt [27]. Basking behavior of sea turtles as well as passive drifting close to the ocean surface typical of sea snakes [48], which can also carry epizoic diatoms [23], can expose the diatoms to damaging levels of heat, irradiance and desiccation.…”

Diatom Diversity on the Skin of Frozen Historic Loggerhead Sea Turtle Specimens

“…With the recent increased interest in diatom diversity on marine vertebrates [1][2][3][4] in general and sea turtles in particular [5][6][7][8][9][10], a considerable number of sea turtle-associated diatom taxa have been described within the last five years [11][12][13][14][15][16][17][18][19][20][21][22][23][24] and it became clear that diatoms constitute an important element of the sea turtle epi-microbiome on both juvenile and adult individuals. Several sea turtle-associated diatom species have thus far only been reported from this substratum, suggesting a very close, even possibly obligatory relationship between the sea turtle-associated diatoms and their hosts.…”