Browse Subject Areas

Click through the PLOS taxonomy to find articles in your field.

For more information about PLOS Subject Areas, click here.

  • Loading metrics

Diatoms and Other Epibionts Associated with Olive Ridley (Lepidochelys olivacea) Sea Turtles from the Pacific Coast of Costa Rica

  • Roksana Majewska ,

    Affiliation Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, II University of Naples, Caserta, Italy

  • Mario Santoro,

    Affiliations Department of Public Health and Infectious Diseases, Section of Parasitology, Sapienza University of Rome, Rome, Italy, Istituto Zooprofilattico Sperimentale del Mezzogiorno, Portici, Italy

  • Federico Bolaños,

    Affiliation Escuela de Biología, Universidad de Costa Rica, San José, Costa Rica

  • Gerardo Chaves,

    Affiliation Escuela de Biología, Universidad de Costa Rica, San José, Costa Rica

  • Mario De Stefano

    Affiliation Department of Environmental, Biological and Pharmaceutical Sciences and Technologies, II University of Naples, Caserta, Italy

Diatoms and Other Epibionts Associated with Olive Ridley (Lepidochelys olivacea) Sea Turtles from the Pacific Coast of Costa Rica

  • Roksana Majewska, 
  • Mario Santoro, 
  • Federico Bolaños, 
  • Gerardo Chaves, 
  • Mario De Stefano


Although the sea turtles have long been familiar and even iconic to marine biologists, many aspects of their ecology remain unaddressed. The present study is the first of the epizoic diatom community covering the olive ridley turtle’s (Lepidochelys olivacea) carapace and the first describing diatoms living on sea turtles in general, with the primary objective of providing detailed information on turtle epibiotic associations. Samples of turtle carapace including the associated diatom biofilm and epizoic macro-fauna were collected from Ostional beach (9° 59´ 23.7´´ N 85° 41´ 52.6´´ W), Costa Rica, during the arribada event in October 2013. A complex diatom community was present in every sample. In total, 11 macro-faunal and 21 diatom taxa were recorded. Amongst diatoms, the most numerous were erect (Achnanthes spp., Tripterion spp.) and motile (Haslea sp., Navicula spp., Nitzschia spp., Proschkinia sp.) forms, followed by adnate Amphora spp., while the most common macro-faunal species was Stomatolepas elegans (Cirripedia). Diatom densities ranged from 8179 ± 750 to 27685 ± 4885 cells mm-2. Epizoic microalgae were either partly immersed or entirely encapsulated within an exopolymeric coat. The relatively low diatom species number, stable species composition and low inter-sample dissimilarities (14.4% on average) may indicate a mutualistic relationship between the epibiont and the basibiont. Dispersal of sea turtle diatoms is probably highly restricted and similar studies will help to understand both diatom diversity, evolution and biogeography, and sea turtle ecology and foraging strategies.


Sea turtles spend their life in the marine environment and may act as hosts to a wide variety of epibiont organisms. Their bodies (especially the broad flattened carapace) provide a very suitable substrate for periphytic growth [1, 2]. Most of these marine epibionts are unspecialized organisms (facultative commensalism) that are also often found associated with physical structures (e.g. ship hulls, dock piling, rocky surfaces), while a few are found almost exclusively on sea turtles (obligate commensalism) [2]. However, epibiosis has only recently started to receive research attention, with interest in its contribution to elucidating the cryptic life history of sea turtles, including their diet, foraging locations, migration routes and times, and stock provenance [2]. Furthermore, epibiosis may have other consequences for the host turtles, including negative effects on swimming and predatory abilities, as well as providing indications of general health status [2, 3].

Most studies to date have focused on the diversity of macro-epibiota and speculation about the possible causes and effects of their associations with host organisms [2]. Few studies have addressed macro-epibiosis from a broad community perspective [2]. Very little is known about the micro-epibiota colonizing sea turtles. Some studies mention sea turtle carapace covered with unidentified algae, but give no further information on the biotic relationships between the epibiont and the basibiont [4, 5, 6]. Little evidence is available relating the ecological and biological role of a sea turtle as a mobile substrate for the, perhaps, many microalgae that are often noted anecdotally growing epizoically on its carapace [5, 7, 8, 9].

Here, we report for the first time direct observations of the epizoic diatom community associated with the olive ridley turtle (Lepidochelys olivacea) carapace, providing the first detailed information on sea turtle microalgal epibionts. The study documents new and previously unknown relationships between epizoic species of diatoms and the olive ridley from the Pacific coast of Costa Rica. In addition, information on sea turtle epibiotic macrofauna that also provide a niche for microepibionts is given.

Material and Methods

General data

This work was a part of the international project “Communities of marine epizoic diatoms, parasites and other epibionts on sea turtles from Costa Rica: ultrastructural, taxonomic, and biogeographical analysis” led by the II University of Naples (Italy) in collaboration with the University of Costa Rica (Costa Rica) and the Sapienza University of Rome (Italy). The study was conducted in the Refugio Nacional de Vida Silvestre Ostional protected area. The study was authorized by both MINAE (Ministerio de Ambiente y Energia) and SINAC (Sistema Nacional de Áreas de Conservación) under resolution ACT-OR-DR-074-13 for the Tempisque Conservation Area (that includes Ostional). Lepidochelys olivacea is a protected species. In Ostional, however, these sea turtles occur in abundance, breed with success and are not currently locally endangered. A collection of epizoic diatoms, epibionts, and ectoparasites was made by scraping individual turtle carapaces with a razor. The method is not invasive, as it is limited to the most external part of the turtle carapace scutes, and it does not harm or cause the animal suffering. All sampling procedures took place as approved by MINAE under a close supervision of park rangers from SINAC. All the procedures involved respect the ethical standards in the Helsinki Declaration of 1975, as revised in 2000 and 2008, as well as the applicable national law.

Samples were collected during the first three days of olive ridley arribada in the second week of October 2013, from the principal nesting beach (approximately 800 m long) of Ostional on the Pacific coast of Costa Rica (Fig 1). Ostional, one of the largest arribada beaches in the world, lies within the Ostional Wildlife Refuge [10]. Before sampling, the curved carapace length notch-to-tip (CCL) of each turtle was measured to the nearest centimetre [11].

Fig 1. Sampling area.

Location of the sampling beach where olive ridley turtles (Lepidochelys olivacea) lay their eggs during arribada events. The map is a representation based on openstreetmap cartography distributed under CC BY-SA 2.0 license ( Part of this work is also based on "brosen windrose" image ( distributed under CC BY 2.5 license.

Material collection and preparation for microscopic observation of diatoms

Carapaces of nesting olive ridleys were shaved with a razor blade and random samples (n > 200) of about 20 cm2 were taken. At least 3 samples were taken from each of the 55 female turtles sampled. Collected material was immediately placed in 50 ml plastic containers and preserved with 4% formaldehyde solution in sea water. Subsequently, the samples were treated in two different ways. For diatom counting and growth form analysis, ca. 1 cm2 subsamples were cut from each of the carapace pieces collected. Sections were then dehydrated through a 25, 50, 60, 70, 80, 90, 95, 100% alcohol series, treated with a Critical Point Dryer (K850 EMITECH), placed on aluminium stubs and sputter-coated with platinum using a DESK V HP TSC Cold Sputter Coater. For taxonomic examination, small pieces (ca. 2 cm2) of collected material were digested with boiling concentrated acid (64% nitric acid and 97% sulphuric acid added at a 1:3 volume ratio respectively), rinsed abundantly with distilled water, centrifuged and decanted. Prior to SEM observations, clean material was mounted on aluminium stubs and sputter-coated with platinum.

Microscopic observations and diatom counts

As preliminary observations using a light microscope indicated that diatom communities associated with different turtle specimens were structurally highly similar, samples from 38 turtles were selected for further detailed observation and analyses under a Zeiss Supra 40 SEM. Diatoms were identified and enumerated on a surface area of ca. 2 mm2 of each of the 3 subsamples derived from the 38 turtles at magnifications ranging between 400x to 60000x. Community quality indicators including Margalef’s species-richness d (d = (S—1)/(logeN), where S = number of species, N = number of individuals), Shannon-Wiener diversity H’ (loge), and Pielou’s evenness index J’ (J’ = H’ /logeS) were calculated for each of the samples. Statistical analyses were performed using PRIMER Ver. 6 [12] software.

Macroscopic epibionts

Macro-epibiont samples were collected from the external surfaces of olive ridley turtles during nesting. They were removed using a pocket-knife or tweezers, and the location from which they were taken was recorded. Samples for morphological identification were preserved in 70% ethanol and the prevalence (i.e. the percentage of turtles upon which a single epibiont species was found) was calculated. Representative specimens are deposited in the Zoological Collection of the University of Costa Rica.


Curved Carapace Length of the 55 examined nesting females ranged from 65 to 71 cm. Eleven species of macro epibionts were present on 2 to 85.5% (Stomatolepas elegans) of the examined turtle individuals (Table 1). Neither epizoic macroalgae nor sessile fauna covered the turtle carapace in a uniform manner. Filamentous algae were concentrated on the posterior and lateral parts of the carapace, while barnacles presented an irregular distribution (Fig 2). A microbial biofilm, however, could clearly be seen to cover the entire carapace.

Table 1. Epibiotic macro fauna found on 55 nesting olive ridley turtles (Lepidochelys olivacea) from Ostional, Pacific coast of Costa Rica.

Fig 2. Olive ridley during the mass nesting event (arribada) at Ostional beach, Costa Rica in October 2014.

a) Females emerged from the ocean after congregating offshore. b & c) Nesting turtle. Brownish biofilm covers the entire carapace but macroepibionts (e.g. macroalgae) prevail on its posterior parts. d) Olive ridley and epizoic barnacles.

In every sample a complex, highly structured diatom community was observed. Twenty-one diatom taxa were found within the epibionts growing on the turtle carapaces (Table 2). Amongst these, eleven taxa (Achnanthes cf. groenlandica, Achnanthes cf. pseudogroenlandica var. phinneyi, Achnanthes sp., Amphora sp. 1, Haslea sp., Navicula cf. rusticensis, Navicula sp., Nitzschia cf. inconspicua, Proschkinia sp., Tripterion sp. 1, and Tripterion sp. 2; Figs 3, 4, 5 and 6) contributed more than 1% of the total diatom number on the surface of at least one turtle specimen examined. These 11 taxa occurred in at least 97% of the samples, while the other 10 species were present only occasionally (3–8% of the samples). Only seven species (Achnanthes cf. groenlandica, Achnanthes cf. pseudogroenlandica var. phinneyi, Achnanthes sp., Amphora sp. 1, Nitzschia cf. inconspicua, Tripterion sp. 1, and Tripterion sp. 2) contributed more than 3% of the total diatom number, all occurring in every sample examined (Table 2), and accounting for 91.5–99.3% of the total diatoms. Apart from rarely observed Azpeitia nodulifera (8% of samples; < 1% of the total diatom number), the diatom community was restricted to pennate diatoms. In general, communities associated with different turtle specimens were composed of the same diatom taxa, but in some cases the contribution of a single taxon to the total diatom community varied considerably. On average, Tripterion spp. and Amphora spp. were the most important components contributing 32.1 and 25.1% of total diatom number, respectively. The relative contribution of Achnanthes spp. varied the most, ranging from 1.5 to 62.6%, with a mean value of 15.3% (S1 Fig). In terms of diatom growth form, erect diatoms (Achnanthes spp., Tripterion spp.) dominated (25.7–81.7%, mean 47.5%), followed by motile (Haslea sp., Navicula spp., Nitzschia spp. Proschkinia sp.; 13–38.6%, mean 27.4%) and adnate forms (Amphora spp.; 3–58.2%, mean 25.1%; Fig 7, S2 Fig).

Fig 3. Scanning electron micrographs of epizoic diatoms associated with olive ridley carapace.

a, b & c) Amphora spp. assemblage. d) Amphora sp. 1, side view. e) Amphora sp. 1, ventral view. f) Amphora sp. 1, dorsal view. g& h) Amphora sp. 2. Scale bars: a = 50 μm, b & c = 20 μm, d-h = 5 μm.

Fig 4. Scanning electron micrographs of epizoic diatoms associated with olive ridley carapace.

a-e) Achnanthes cf. pseudogroenlandica var. phinneyi: a) monospecific cluster of A. cf. pseudogroenlandica var. phinneyi growing on the turtle carapace, b) internal view of the raphe valve, c) chain of the attached cells, d) single cell, external view, e) details of the central are, f) Achnanthes sp. 1, a single cell in girdle view. g-i) Haslea sp. 1: g) entire cell in external view, h) details of the central area, i) details of the raphe endings. Scale bars: a = 50 μm, b & g = 5 μm, c, d & f = 10 μm, e, h & I = 1 μm.

Fig 5. Scanning electron micrographs of epizoic diatoms associated with olive ridley carapace.

a-c) Proschkinia sp.: a) valve view, b) diagonal view, c) girdle view. d & e) Tripterion sp. 1. f-i) Tripterion sp. 2: f) valve view (external), g) girdle view, h) valve view (internal), i) cluster of cells attached to the turtle carapace. Scale bars: a-c &i = 5 μm, d-h = 1 μm.

Fig 6. Scanning electron micrographs of epizoic diatoms associated with olive ridley carapace.

a-c) Navicula cf. rusticensis: a) valve view, b) details of the central area, c) details of external raphe ending.d-f) Navicula sp. 1: d) valve view, e) cell immersed in the mucilage tube, f) details of the central area. g-i) Nitzschia sp. 1: g) diagonal view, h) valve view (external), i) valve view (internal). Scale bars = 1 μm.

Fig 7. Diatom growth form percent contribution to total diatom abundance.

Although different diatom species dominated locally creating monospecific clusters, no bare areas were observed. Diatoms covered all available surfaces, ranging from 8179 ± 750 to 27685 ± 4885 cells mm-2 (17648 ± 5949 cells mm-2 on average) (Table 3). Values of the Margalef’s species-richness (d), Pielou’s evenness (J’), and Shannon-Wiener diversity index (H’) ranged from 0.87 to 1.38 (mean 1.08), 0.56–0.86 (mean 0.71), and from 1.41 to 2.1 (mean 1.73), respectively (Table 3). Many diatom cells were partly immersed or entirely encapsulated within an exopolymeric coat formed most likely by either the diatoms themselves or fungal or bacterial populations coexisting with the stratified diatom community (Figs 3, 4, 5 and 6).

According to SIMPER (Similarity Percentages—species contributions) analysis, samples collected from each turtle contained high within-group average similarities (74.2–96%; on average 86.6%) and low inter-group dissimilarities (4.5–33.5%; on average 14.4%). ANOSIM (Analysis of Similarities) confirmed that diatom community associated with each turtle was not significantly different from the others in terms of both species composition (Global R = 0.095, p<0.05) and growth form structure (Global R = 0.075, p<0.05; S2 Fig).


Exploration of as yet unknown, undescribed marine habitats often yields new diatom taxa. Amongst these, some of the most intriguing forms are epizoic diatoms, which often have traits of obligate epibionts [13, 14, 15]. The nature of the close relationships between substrate organism and its epibionts requires further detailed investigation. However, some of the reported symbiosis-like associations [14, 16, 17] may in fact be species-specific and we may expect many new epizoic taxa to be discovered along with the examinations of generally understudied epizoon. In the present study, in spite of extensive literature research and consultation with diatom taxonomic experts, we found that the morphology of many of the observed taxa did not correspond precisely with descriptions of known diatom species. For the most common of these taxa SEM micrographs are provided (Figs 3, 4, 5 and 6). A detailed taxonomic analysis was not the specific objective of this survey but is clearly required in future.

The high density and specific composition of epizoic diatom communities may perform an ecological function through providing an unique microhabitat for benthic micro- and mesofauna in the otherwise rather uniform and inaccessible pelagic environment. Epizoic habitats, such as those provided by sea turtles, constitute patches of high benthic primary production and contribute to the biodiversity and productivity of the marine ecosystem. The magnitude of this contribution, however, remains unknown. The observed epibiotic diatom densities, reaching 27685 ± 4885 cells mm-2, are amongst the highest reported to date from various biotic substrates collected in different parts of the world [18, 19, 20].

Taking into consideration the sea turtle life cycle and habits (e.g. deep dives, periodical emerging to the water surface, long migrations), the turtle carapace may appear to be a stressful habitat for diatoms. Nevertheless, the associated diatom communities were well-developed and highly-structured. The high contribution of erect diatoms to the total diatom number indicates 3-dimensionality and vertical stratification. The fact that all examined olive ridley females supported well-developed diatom communities is in accordance with the Caine’s [21] observation that the mating activities in sea turtles probably do not significantly affect the epibiotic community, although further support for this assertion requires examination of the microepibionts present on both sexes of turtle. In the present study, copious amounts of rich organic film composed most likely of bacteria and diatom extracellular polymers were observed in every sample. Mucilage substances produced by diatoms in the form of various structures (pads, stalks, tubes, adhering films, etc.) have numerous functions and contribute greatly to their biological success. Extracellular polymeric substances (EPS), due to their specific morphology, ultrastructure and biochemistry, play an important ecological role, for example in protecting diatom cells from desiccation, harmful solar radiation or excessive grazing, and increasing the physical stability of the microbial community [22, 23, 24]. Moreover, according to some authors [25, 26, 27], the presence of a bacterial biofilm may promote the attachment of microalgae, including diatoms.

Epizoic diatom growth on sea turtle carapaces is likely to be a common phenomenon occurring in various marine habitats. The low species number and relatively stable species composition (low inter-sample dissimilarities) observed here may suggest a mutualistic relationship between the epibiont and the basibiont. While the potential benefits for the epizoic diatom are likely to include factors such as provision of an appropriate solid substrate as well as a potential nutrient and CO2 source [19, 28], any benefit to the sea turtle is not clear. It seems unlikely that microorganism such as diatoms, even when present in high densities, may significantly disadvantage the sea turtle. Nevertheless, by creating a specific microhabitat suitable for larger sessile and mobile organisms, diatoms may indirectly contribute to the negative effect of increased mass and friction. Alternatively, epibionts may provide camouflage or protection against desiccation. How important this may be for a sea turtle is open to conjecture. It is a remarkable fact, however, that the associated organisms influence many areas of the interactions between the host organism and its biotic and abiotic environment [29, 30].

It is known that many diatoms are sensitive to environmental parameter changes on very small scales [31]. This may underlie the observation that the rather unstable habitat provided by the sea turtle is occupied by few diatom species overall. These species have presumably adapted successfully to the unusual combination of conditions found on the turtle carapace, and are able to survive and develop dense populations there. While sessile diatoms depend strongly on hard substrates which allow them to complete their ontogenesis, the availability of solid surfaces often becomes a limiting factor [32, 33]. Any adaptation enabling a diatom to settle and develop on a living and moving substrate may therefore provide a competitive advantage. A specialised epibiont will benefit from reduced competition for space, as the living substrate may be poorly suited to other colonizers [29]. We speculate that the observed epizoic community in its present form may be a result of ecological vicariance: differences in the habitat of originally benthic species provided opportunities for specialization and speciation within local diatom groups [29, 34]. On the other hand, some of the taxa that usually occur together and are typical for a certain microhabitat may as well be common to the surrounding habitats [35]. According to some reports [36] mucilaginous attachments produced by several typically epibiotic diatoms allow the attachment of other nonmucilaginous cells. In this way, local unstalked diatoms may attach to the mucilaginous diatom substrate when a diatom-bearing sea turtle forages in the vicinity of the natural substrates of these diatoms. If so, there is potential for epizoic diatom communities to be used as biomarkers indicating foraging sites for different sea turtle populations. This novel approach might help to bridge the wide gap in general understanding of sea turtle foraging ecology and life cycle, and we encourage turtle researchers to consider the role of epizoic microorganisms (including diatoms) in their studies.

Supporting Information

S1 Fig. Dominant diatom taxa percent contribution to total diatom abundance.


S2 Fig. Diatom growth form contribution to total diatom abundance.

Standard deviation bars indicate the inter-sample variability.



We would like to thank Peter Convey for his advice, helpful hints and linguistic revision of the manuscript. We are also deeply grateful to Bart Van de Vijver who helped to clarify some taxonomic problems.

Author Contributions

Conceived and designed the experiments: RM MS FB GC MD. Performed the experiments: RM MS. Analyzed the data: RM. Contributed reagents/materials/analysis tools: RM MS FB GC MD. Wrote the paper: RM. Obtained permissions for turtle epibiont sampling: FB GC. Collection of samples: MS FB GC MD.


  1. 1. Lutz PL, Musick JA (1997) The Biology of Sea Turtles. CRC Press, Inc., Florida
  2. 2. Frick MG, Pfaller JB (2013) Sea turtle epibiosis. In: Wyneken J, Lohmann KJ, Musick JA (eds) The Biology of Sea Turtles Vol. 3. CRC Press, Boca Raton FL, pp. 399–426
  3. 3. Santoro M, Morales JA, Rodríguez-Ortíz B (2007) Spirorchiidiosis (Digenea: Spirorchiidae) and lesions associated with parasites in Caribbean green sea turtles (Chelonia mydas). Vet Rec 161: 482–486 pmid:17921440
  4. 4. Schwartz FJ (1978) Behavioral and tolerance responses to cold water temperatures by three species of sea turtles (Reptilia, Cheloniidae) in North Carolina. Fla Mar Res Publ 33: 16–18
  5. 5. Frick MG, Williams KL, Robinson M (1998) Epibionts associated with nesting loggerhead sea turtle (Caretta caretta) in Georgia, USA. Herpetol Rev 29: 211–214
  6. 6. Báez JC, Camiñas JA, Valeiras J, Conde F, Flores-Moya A (2002) Preliminary check-list of the epizootic macroalgae growing on loggerhead turtles in the western Mediterranean Sea. Mar Turt Newsl 98: 1–2
  7. 7. Frick MG, Williams KL, Markesteyn EJ, Pfaller JB, Frick RE (2004) New records and observations of epibionts from loggerhead sea turtles. Southeast Nat 3: 613–620
  8. 8. Grossman A, Sazima C, Bellini C, Sazima I (2006) Cleaning symbiosis between hawksbill turtles and reef fishes at Fernando de Noronha Archipelago, off Northeast Brazil. Chelonian Conserv Biol 5: 284–288
  9. 9. Sazima C, Grossman A, Sazima I (2010) Turtle cleaners: reef fishes foraging on epibionts of sea turtles in the tropical Southwestern Atlantic, with a summary of this association type. Neotrop Ichthyo l8: 187–192
  10. 10. Campbell LM (1998) Use them or lose them? Conservation and the consumptive use of marine turtle eggs at Ostional, Costa Rica. Environ Conserv 25: 305–319
  11. 11. Bolten AB (1999) Techniques for Measuring Sea Turtles. In: Eckert KL, Bjorndal KA, Abreu-Grobois FA, Donnelly M (eds) Research and Management Techniques for the Conservation of Sea Turtles. IUCN/SSC Marine Turtle Specialist Group Publication N° 4, Washington, pp 110–114
  12. 12. Clarke KR, Gorley RN (2006) PRIMER V6: user manual/tutorial. PRIMER-E Ltd, Plymouth, UK
  13. 13. Hart TJ (1935) On the diatoms of the skin film of whales and their possible bearing on problems of whale movements. Discov Rep 10: 249–282
  14. 14. Nemoto T (1956) On the diatoms of the skin films of whales in the northern Pacific. Sci Rep Whales Res Inst 11: 99–132
  15. 15. Denys L, De Smet WH (2010) Epipellisoiketis (Bacillariophyta) on harbor porpoises from the North Sea Channel (Belgium). Pol Bot J 55: 175–182
  16. 16. Holmes RW (1985) The morphology of diatoms epizoic on Cetaceans and their transfer from Cocconeis to two new genera, Bennettella and Epipellis. Brit Phycol J 20: 43–57
  17. 17. Holmes RW, Nagasawa S, Takano H (1993) The morphology and geographic distribution of epidermal diatoms of the dall's porpoise (Phocoenoides dalli True) in the Northern Pacific Ocean. Bulletin of the National Science Museum, Series B (Botany), Tokyo, 19: 1–18
  18. 18. Romagnoli T, Bavestrello G, Cucchiari EM, De Stefano M, Di Camillo CG, Pennesi C, et al. (2007) Microalgal communities epibiontic on the marine hydroid Eudendriumracemosum in the Ligurian Sea during an annual cycle. Mar Biol 151: 537–552
  19. 19. Totti C, Romagnoli T, De Stefano M, Di Camillo CG, Bavestrello G (2011) The Diversity Of Epizoic Diatoms. In: Dubinsky Z, Seckbach J (eds) All flesh is grass. Cellular Origin, Life in Extreme Habitats and Astrobiology 16, pp 323–343
  20. 20. Majewska R, Gambi MC, Totti CM, Pennesi C, De Stefano M (2013) Growth form analysis of epiphytic diatom communities of Terra Nova Bay (Ross Sea, Antarctica). Polar Biol 36: 73–86
  21. 21. Caine EA (1986) Carapace epibionts of nesting loggerhead sea turtles: Atlantic coast of USA. J Exp Mar Biol Ecol 95: 15–26
  22. 22. Hostetter HP, Hoshaw RW (1970) Environmental factors affecting resistance to desiccation in the diatom Stauroneisanceps. Am J Bot 57: 512–518
  23. 23. Davis JH (1972) Survival records in the algae and the survival role of certain algal pigments, fats and mucilaginous substances. Biologist 54: 52–93
  24. 24. Hoagland KD, Rosowski JR, Gretz MR, Roemer SC (1993) Diatom extracellular polymeric substances: function, fine structure, chemistry, and physiology. J Phycol 29: 537–566
  25. 25. Tosteson TR, Corpe WA (1975) Enhancement of adhesion of the marine Chlorella vulgaris to glass. Can J Microbiol 21: 1025–1031 pmid:1148941
  26. 26. Fukami K, Sakami T, Ishida Y, Tanaka N (1989) Effect of bacterial film on the growth of the attached diatom, Nitzschia sp. In: Miyachi S, Karube I, Isida Y (eds) Current Topics in Marine Biotechnology. Jpn Soc Mar Biotechnol, pp 415–418
  27. 27. Sekar R, Venugopalan VP, Satpathy KK, Nair KVK, Rao VNR (2004) Laboratory studies on adhesion of microalgae to hard substrates. Hydrobiologia 512: 109–116
  28. 28. Di Camillo C, Puce S, Romagnoli T, Tazioli S, Totti C, Bavestrello G (2005) Relationships between benthic diatoms and hydrozoans (Cnidaria). J Mar Biol Ass UK 85: 1373–1380
  29. 29. Wahl M, Mark O (1999) The predominantly facultative nature of epibiosis: experimental and observational evidence. Mar Ecol Prog Ser 187: 59–66
  30. 30. Gillan DC, Cadée GC (2000) Iron-encrusted diatoms and bacteria epibiotic on Hydrobia ulvae (Gastropoda: Prosobranchia). J Sea Res 43: 83–91
  31. 31. Stoermer EF, Smol JP (2010) The diatoms: applications for environmental and earth sciences, 2nd edn Cambridge University Press, New York, pp 267–286
  32. 32. Jackson JBC, Buss LW (1975) Allelopathy and spatial competition among coral reef invertebrates. Proc Natl Acad Sci USA 72: 5160–5163 pmid:16592298
  33. 33. Patil JS, Anil AC (2000) Epibiotic community of the horseshoe crab Tachypleus gigas. Mar Biol 136: 699–713
  34. 34. Wiens JJ (2004) Speciation and ecology revisited: phylogenetic niche conservatism and the origin of species. Evolution 58: 193–197 pmid:15058732
  35. 35. McClatchie S, Kawachi R, Dalley DE (1990) Epizoic diatoms on the euphausiid Nyctiphanesaustralis: consequences for gut-pigment analyses of whole krill. Mar Biol 104: 227–232
  36. 36. Fee EJ, Drum RW (1973) Diatoms epizoic on copepods parasitizing fishes in the Des Moines River, Iowa. Am Midl Nat 81: 318–373