Roksana Majewska

Nord University | HIBO · Faculty of Biosciences and Aquaculture

Our understanding of the importance of microbiomes on large aquatic animals—such as whales, sea turtles and manatees—has advanced considerably in recent years. The latest observations indicate that epibiotic diatom communities constitute diverse, polyphyletic, and compositionally stable assemblages that include both putatively obligate epizoic and...

The loggerhead sea turtle is considered a keystone species with a major ecological role in Mediterranean marine environment. As is the case with other wild reptiles, their outer microbiome is rarely studied. Although there are several studies on sea turtle’s macro-epibionts and endo-microbiota, there has been little research on epibiotic microbiota...

Healthy surface microbiota of humans and other animals is known to be beneficial for their immunity, battling pathogens and overall wellbeing. However, microbiome research of wild animals such as sea turtles is often neglected due to lack of commercial interest and therefore reptiles are one of the most understudied groups in that aspect. Neverthel...

Loggerhead sea turtle is considered a keystone species with major ecological role in Mediterranean marine environment. As with other wild reptiles, their outer microbiome is rarely studied. Although there are several studies on sea turtle's macro-epibionts and endo-microbiota, there has been little research on epibiotic microbiota associated with s...

Build a major genomics resource on the continent to help breeders and conservationists.

Two new species of the previously monospecific diatom genus Druehlago were discovered during the ongoing studies exploring the epizoic and epiphytic diatom flora of the Southern African coasts. These species are formally described here as D. craspedostauriformis sp. nov. and D. lobbanii sp. nov. Detailed morphological examination using both light a...

Background: Our understanding of the importance of microbiomes on large aquatic animals—such as whales, sea turtles and manatees—has advanced considerably in recent years. Recent activity describing the epizoic diatoms growing on marine vertebrates suggests that these epibiotic diatom communities constitute diverse, polyphyletic, and compositionall...

Our understanding of the importance of microbiomes on large aquatic animals—such as whales, sea turtles and manatees—has advanced considerably in recent years. Recent activity describing epizoic diatoms suggests that epibiotic diatom communities constitute diverse, polyphyletic, and compositionally stable assemblages that include both putatively ob...

Hyalosira gene sequences are divided into two clades within different families. We examined authentic material of Hyalosira (isotype material of H. obtusangula, synonymous with H. delicatula) and voucher specimens of published sequences, and pooled our observations of Hyalosira-like taxa from benthic and epizoic habitats in several parts of the glo...

Although diatoms colonize a vast diversity of immersed hard-surfaced objects and organisms, many diatom species, and sometimes entire genera, show a clear preference towards a particular type of substratum. Studies of animal-associated diatoms indicate that some epizoic forms may require this specific habitat to thrive, and new diatom taxa are expe...

The inability to thoroughly examine diatom type material existing only in resin-mounted permanent slides is a common frustration for diatomologists. Here, we present an efficient, inexpensive, and straightforward technique to extract siliceous exoskeletons of diatoms from permanent slides prepared with commonly used mounting media. Van Heurck’s sli...

The current study focuses on four species from the primarily marine diatom genus Craspedostauros that were observed growing attached to numerous sea turtles and sea turtle-associated barnacles from Croatia and South Africa. Three of the examined taxa, C. danayanus sp. nov., C. legouvelloanus sp. nov., and C. macewanii sp. nov. are described based o...

Diatom community composition and abundances on different thallus parts of adult and juvenile specimens of Ecklonia maxima and Laminaria pallida were examined in False Bay, South Africa, using light and scanning electron microscopy. Altogether, 288 thallus portions were analysed. Diatom abundances ranged from 0 to 404 cells mm −2 and were generally...

In recent years, biofilm-forming diatoms have received increased attention as sea turtle epibionts. However, most of the research has focused on carapace-associated taxa and communities, while less is known about diatoms growing on sea turtle skin. The current study investigated diatom diversity on the skin of loggerhead sea turtle heads detached f...

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 (Gree...

Tursiocola, a presumably exclusively epizoic diatom genus, comprises species found on various aquatic animals such as cetaceans, manatees, and marine and freshwater turtles. The genus is characterised by linear or lanceolate valves with well-developed pseudosepta at both poles, a valvocopula with three pairs of siliceous tabs, and a butterfly-like...

The current study investigated diatom communities on juvenile green turtles foraging in neritic habitats around five Iranian islands. The primary objectives were to (1) compare species composition, growth form structure, and abundance of diatom communities associated with sea turtles foraging within the restricted boundaries of local feeding pastur...

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 function and role of those mainly photosynthetic or...

A novel diatom species belonging to the genus Nagumoea is described based on detailed light and scanning electron microscopy observations. The new taxon was found abundantly in several samples collected from seagrass on the southernmost coasts of Mozambique, Southern Africa. While the new species shows characters (e.g. scalariform valvocopula, fibu...

The Namib Desert is one of the world’s only truly coastal desert ecosystem. Until the end of the 1st decade of the twenty-first century, very little was known of the microbiology of this southwestern African desert, with the few reported studies being based solely on culture-dependent approaches. However, from 2010, an intense research program was...

A new Lucanicum species, L. ashworthianum Majewska, K.Robert & Van de Vijver sp. nov., was found in multiple samples of biofilm growing on loggerhead sea turtles Caretta caretta and their symbiotic barnacles Chelonibia testudinaria collected on the beaches of Kosi Bay, eastern coast of South Africa, during the two nesting seasons (the austral summe...

The diatom genus Proschkinia is a common element of biofilms covering diverse substrata in saline inland or shallow coastal environments. It can be distinguished from other naviculoid taxa by its lanceolate valves with a fistula located within the central area and numerous open girdle bands with a U-shaped cross-section and a single row of perforat...

The loggerhead sea turtle is the most common species of marine turtle in the Adriatic Sea. Here, the neritic habitats represent important feeding pasture for these omnivorous reptiles. Currently, despite of the extensive conservation effort, what can be called the anthropogenic disturbance remains the greatest threat to these animals. Due to variou...

Kelp forests are believed to host a large biomass of epiphytic fauna and flora, including diatoms, which constitute the base of aquatic food webs and play an important role in the transfer of energy to higher trophic levels. Epiphytic diatom assemblages associated with two common species of South African kelps, Ecklonia maxima and Laminaria pallida...

Kelp forests are believed to host a large biomass of epiphytic fauna and flora, including diatoms, which constitute the base of aquatic food webs and play an important role in the transfer of energy to higher trophic levels. Epiphytic diatom assemblages associated with two common species of South African kelps, Ecklonia maxima and Laminaria pallida...

The loggerhead sea turtle is widely distributed throughout the world's oceans with a now-thriving population in the Mediterranean Sea. Loggerhead sea turtles seem to harbor a diverse assemblage of macro- and micro-epibionts living on their shells and skin. Recent studies focused on sea turtle-associated diatoms indicate that some of them may be exc...

A growing interest in the relationship between sea turtles and their epibionts (i.e., marine organisms that attach to, or dwell on the exterior shell or skin of sea turtles) resulted in a workshop focused on sea turtle epibiosis at the 37th International Sea Turtle Symposium, Las Vegas, Nevada (Pinou et al. 2017). The primary objectives of the work...

Diagnostics: Proton state of secreted proteins in blood helps identify cancer A blood test that measures whether molecules secreted by cells contain titratable proton atoms can accurately discriminate between patients who have cancer and those who don’t. Titratable species may in turn influence the protonation state of a solution, i.e. the number o...

Diatomaceous earth, or diatomite, is produced through the accumulation of diatom (Bacillariophyceae) skeletons (i.e. cell walls called frustules) made of amorphous silica. The porous, highly symmetrical structure and microscopic size of diatom cell walls make them ideal constituents of sensing devices and analytical chips. Here, we propose chemical...

Secretome of primary cultures is an accessible source of biological markers compared to more complex and less decipherable mixtures such as serum or plasma. The protonation state (PS) of secretome reflects the metabolism of cells and can be used for cancer early detection. Here, we demonstrate a superhydrophobic organic electrochemical device that...

Several populations of a new Craspedostauros species were observed on museum specimens of juvenile green turtle and Kemp’s ridleys collected from Long Island Beach, New York, USA. The new taxon, Craspedostauros alatus Majewska & Ashworth sp. nov., exhibits a distinctive set of morphological features typical of the genus, including cribrate areolae,...

ABSTRACT: The animal/plant associated microbiota play a key role in the survival and fitness of their hosts. The microbial communities associated with the host’s body, both on the external surfaces and inside the guts, support their host's immune system and provide protection from pathogens. Although sea turtles have been studied by marine biologis...

The current study characterizes numerous populations of epizoic “gomphonemoid” diatoms found on five sea turtle species inhabiting all three oceans, highlighting both the remarkable morphological plasticity found within each of these populations and the lack of morphological discontinuity among them. As diatom epibiosis on sea turtles (and other ma...

Rafting on macro-algae (Sargassum) of symbiont-bearing Larger Benthic Foraminifera, key to their dispersal in recent and ancient oceans

Diatom shells are a natural, theoretically unlimited material composed of silicon dioxide, with regular patterns of pores penetrating through their surface. For their characteristics, diatom shells show promise to be used as low cost, highly efficient drug carriers, sensor devices or other micro-devices. Here, we demonstrate diatom shells functiona...

Significant advances in the understanding of the molecular determinants of fibrillogenesis can be expected from comparative studies of the aggregation propensities of proteins with highly homologous structures but different folding pathways. Here, we fully characterize, by means of stopped-flow, T-jump, CD and DSC experiments, the unfolding mechani...

We present here an ultrastructure-based revision of the diatom genus Anorthoneis using both light (LM) and electron microscopy (SEM). The original slides and type material of all known Anorthoneis species were analysed and new, previously unseen, morphological features of the frustules, such as rota-like vela and ligulate structures around the valv...

A new Labellicula species, L. lecohuiana Majewska & Van de Vijver sp. nov., was observed living epizoically on the carapaces of green sea turtles in Costa Rican coastal waters. The new species, showing a narrowly lanceolate valve outline, is characterized by uniseriate striae composed of one large macroareola, a rather simple raphe structure with h...

The first reports of diatoms growing on marine mammals date back to the early 1900s. However, only recently has direct evidence been provided for similar associations between diatoms and sea turtles. We present a comparison of diatom communities inhabiting carapaces of green turtles Chelonia mydas sampled at two remote sites located within the Indi...

Tropical estuaries often have a low buffering capacity and may experience acidification, both naturally through microbial degradation and runoff from acid sulphate soils (ASS), or from various anthropogenic sources. Here, we describe phytoplankton communities from the turbid, acidified, and eutrophic Sungai Brunei and Brunei Bay estuarine system. F...

It has been known for a long time that marine mammals, such as whales and dolphins, host a very specific epizoic community on their skin. Whether or not a similar community exists on the carapaces of sea turtles is less studied. The present paper describes two new epizoic diatoms from the genus Achnanthes sensu stricto, Achnanthes elongata and Achn...

As High Arctic environments are particularly sensitive to global and regional climate changes, a growing number of studies have focused on that region. It has been shown that living and fossil diatoms can be successfully used to track environmental changes in polar habitats. Nevertheless, the diatom flora of many Arctic areas remains unknown. The p...

We used electroless deposition to fabricate clusters of silver nanoparticles (NPs) on a silicon substrate. These clusters are plasmonics devices that induce giant electromagnetic (EM) field increments. When those EM field are absorbed by the metal NPs clusters generate, in turn, severe temperature increases. Here, we used the laser radiation of a c...

The macro-epibiotic communities of sea turtles have been subject to growing interest in recent years, yet their micro-epibiotic counterparts are almost entirely unknown. Here, we provide the first evidence that diatoms are epibionts for all seven extant species of sea turtle. Using Scanning Electron Microscopy, we inspected superficial carapace or...

Despite recent advances in polar marine biology and related fields, many aspects of the ecological interactions that are crucial for the functioning of Antarctic shallow water habitats remain poorly understood. Although epiphytic diatoms play an essential role in the Antarctic marine food web, basic information regarding their ecology, biodiversity...

Average percent contribution of diatom growth forms to the total number of diatoms found on the surface of epiphytic sessile microfauna in different months (based on all replicates collected in Terra Nova Bay). (TIF)

Average percent contribution of diatom growth forms to the total number of diatoms found on the macroalgal surface at selected sampling sites. (TIF)

Average growth form abundances of diatoms associated with Phyllophora antarctica and Plocamium cartilagineum. CR—Cape Russell, AD—Adélie Cove, F—Faraglione, M—Molo, TB—Tethys Bay, Dec—December, Jan—January, Feb—February. (TIF)

Average growth form abundances of diatoms associated with sessile fauna epiphytic on Phyllophora antarctica and Plocamium cartilagineum. CR—Cape Russell, AD—Adélie Cove, F—Faraglione, M—Molo, TB—Tethys Bay, Dec—December, Jan—January, Feb—February. (TIF)

List of samples. (DOCX)

Average abundance of diatoms associated with Phyllophora antarctica and Plocamium cartilagineum, and their contribution to the dissimilarity found between the groups. (DOCX)

Average abundance of diatoms associated with Phyllophora antarctica and Iridaea cordata, and their contribution to the dissimilarity found between the groups. (DOCX)

Average percent contribution of diatom growth forms to the total number of diatoms found on the macroalgal surface in different months (based on all macroalgal replicates collected in Terra Nova Bay). (TIF)

Average abundance of diatoms associated with Plocamium cartilagineum and Iridaea cordata, and their contribution to the dissimilarity found between the groups. (DOCX)

Marine mammals such as whales and dolphins have been known for a long time to host a very specific epizoic community on their skin. Less known however is the presence of a similar community on the carapaces of sea turtles. The present study is the first describing new taxa inhabiting sea turtle carapaces. Samples, collected from nesting olive ridle...

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 primar...