Epizoic Community Research Articles

Specificity of diatom communities attached on the carapace of the European pond turtle (<em>Emys orbicularis</em>)

Periphytic diatoms growing on aquatic turtle carapaces provide an interesting example of biofouling on an animal substrate. This study dealt with the question of the specificity of epizoic diatom communities for the case of the European pond turtle (Emys orbicularis) and across five water bodies in South-Eastern France. 375 diatom taxa have been identified on the European pond turtle carapace. The results showed that the epizoic communities of the five sites were significantly different from each other. The epizoic diatom communities could be clearly distinguished from epilithic and epiphytic communities only in two out of five sites. The differences in composition at the two sites resulted from the greater abundance of some species and life forms. However, the characteristic pattern of diatom communities on the carapaces was not the same at the two sites. It therefore appeared that the European pond turtle’s carapace did not harbour specific diatom communities and can rather be considered a neutral substrate.

Molecular and morphological characterisation of Melanothamnus testudinis sp. nov. (Rhodophyta, Rhodomelaceae) and its distinction from Polysiphonia carettia

ABSTRACT The association between epizoic algae and animals is well known, and turtles are among the animals that most commonly host epibiont communities. The most studied algal component of the epizoic communities found on turtles is represented by diatoms, while other algal taxa, like the Rhodophyta, are less investigated. During a survey started to study the epibionts associated with loggerhead turtles, Caretta caretta, cared for at the WWF Sea Turtle Rescue Center of Lampedusa Island (Sicily, Italy), specimens of Rhodomelaceae (Rhodophyta) were collected for taxonomic investigation. The resulting vegetative, reproductive, and molecular data of those specimens characterised the new species described here as Melanothamnus testudinis sp. nov. We also evaluated the holotype of Polysiphonia carettia Hollenberg, an epibiont of C. caretta reported from the Mediterranean Sea. This investigation confirmed the distinction of M. testudinis from P. carettia and suggested that previous Mediterranean and Canarian records of the latter species are probably M. testudinis.

Do marine sponges host epizoic tardigrades?

Just over 200 species of marine tardigrades have been described, and most of these have been collected in sand and other sediments. However, several species are known to associate with other invertebrates such as barnacles, bryozoans, and holothurians. It is possible that many epizoic tardigrade species remain to be discovered, since surveys of tardigrades on other potential animal hosts are very rare. Sponges, with extensive cavities, constant water flow, and protective secondary compounds, are known to harbour a highly diverse epizoic community, but there are no published studies indicating that marine tardigrades are among this community, and there is only one published record of tardigrades from freshwater sponges. We collected 30 samples of marine sponges, consisting of 12 species, from the central Bahamas. We processed these for tardigrades and other meiofauna using the freshwater shock technique. One unusual non-tardigrade in our samples was Loxosomella sp., an entoproct which is a known commensal on sponges. Here we also provide the first record of marine tardigrades associated with marine sponges. However, we found only one species, Archechiniscus bahamensis, which is the most common species occurring free-living in Bahamian subtidal sand. Therefore, we conclude that marine sponges, at least in the Bahamas, do host epizoic marine tardigrades, but they may not be a unique or important host for marine tardigrades.

Shared Epizoic Taxa and Differences in Diatom Community Structure Between Green Turtles (Chelonia mydas) from Distant Habitats.

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 Indian (Iran) and Atlantic (Costa Rica) Ocean basins. Diatom observations and counts were carried out using scanning electron microscopy. Techniques involving critical point drying enabled observations of diatoms and other microepibionts still attached to sea turtle carapace and revealed specific aspects of the epizoic community structure. Species-poor, well-developed diatom communities were found on all examined sea turtles. Significant differences between the two host sea turtle populations were observed in terms of diatom abundance and their community structure (including growth form structure). A total of 12 and 22 diatom taxa were found from sea turtles in Iran and Costa Rica, respectively, and eight of these species belonging to Amphora, Chelonicola, Cocconeis, Navicula, Nitzschia and Poulinea genera were observed in samples from both locations. Potential mechanisms of diatom dispersal and the influence of the external environment, sea turtle behaviour, its life stage, and foraging and breeding habitats, as well as epibiotic bacterial flora on epizoic communities, are discussed.

Two new epizoic Achnanthes species (Bacillariophyta) living on marine turtles from Costa Rica

AbstractIt 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

Chelonicola and Poulinea, two new gomphonemoid diatom genera (Bacillariophyta) living on marine turtles from Costa Rica

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 ridley sea turtles (Lepidochelys olivacea) on Ostional Beach (Costa Rica), were studied using light and scanning electron microscopy. Two unknown small-celled gomphonemoid taxa were analysed in more detail and are described as two new genera, closely related to other gomphonemoid genera with septate girdle bands, such as Tripterion, Cuneolus and Gomphoseptatum. Chelonicola Majewska, De Stefano & Van de Vijver gen. nov. has a flat valve face, uniseriate striae composed of more than three areolae, simple external raphe endings, internally a siliceous flap over the proximal raphe endings and lives on mucilaginous stalks. Poulinea Majewska, De Stefano & Van de Vijver gen. nov. has at least one concave valve, uniseriate striae composed of only two elongated areolae, external distal raphe endings covered by thickened siliceous flaps and lives attached to the substrate by a mucilaginous pad. Chelonicola costaricensis Majewska, De Stefano & Van de Vijver sp. nov. and Poulinea lepidochelicola Majewska, De Stefano & Van de Vijver sp. nov. can be separated based on stria structure, girdle structure composed of more than 10 copulae, raphe structure and general valve outline. A cladistics analysis of putative members of the Rhoicospheniaceae indicates that the family is polyphyletic. Chelonicola and Poulinea are sister taxa, and form a monophyletic group with Cuneolus and Tripterion, but are not closely related to Rhoicosphenia, or other genera previously assigned to this family. Features used to help diagnose the family such as symmetry and presence of septa and pseudosepta are homoplastic across the raphid diatom tree of life.

Epizoic communities of Rotifera inhabiting sponges in freshwaters of North-Eastern Poland

Abstract The species structure of epizoic communities of Rotifera was analyzed on three species of freshwater sponges: Spongilla fragilis Leydy, Spongilla lacustris (L.) Vejd. and Ephydatia fluviatilis (L.) Vejd. In total, all studied sponges hosted 87 rotifer species. Epizoic communities of Rotifera from particular sponges were very diverse, reach in species and unique. Thus, sponges covering both natural substrates and artifacts may create “hot-points” of rotifer species diversity and therefore may play an important role in re-naturalization of wastes.

Cutidiplogaster manati n. gen., n. sp. (Nematoda: Diplogastridae) from skin lesions of a West Indian manatee (Sirenia) from the Okinawa Churaumi Aquarium

AbstractA new species of the nematode taxon Diplogastridae is described on morphology and additional molecular data. The new species cannot be grouped in any of the currently accepted diplogastrid genera. Therefore, we introduce the new genus Cutidiplogaster n. gen. along with the description of our new species Cutidiplogaster manati n. gen., n. sp. Cutidiplogaster manati n. gen., n. sp. was isolated from skin lesions of manatees, Trichechus manatus manatus, kept in Okinawa Churaumi Aquarium, Japan. The specimens were found anchored with their extraordinarily long tails to the small, thick epidermal bumps within thread algae that form part of the epizoic community on the manatee skin. Cutidiplogaster manati n. gen., n. sp. is characterised by the tube-shaped and finely annulated postdental part of the stegostom that makes it distinct from all other Diplogastridae so far known, and the coiled long tail that makes it unique in comparison with all known diplogastrids. On the basis of detail in stoma morphology in C. manati n. gen., n. sp., we discuss implications in homologising diplogastrid mouthparts and their evolution.

Epizoic communities of Rotifera on freshwater bivalves

Abstract The species structure of epizoic communities of Rotifera was analyzed on three species of freshwater bivalves: Anodonta anatina (Linnaeus), A. cygnea (Linnaeus) and Unio tumidus (Philipsson) from lakes and rivers of north-eastern Poland. Epizoic rotifer communities were abundant and relatively rich in species. The communities were mostly built of common littoral species, like Colurella uncinata, Lecane flexilis, Lepadella quadricarinata, Ptygura melicerta. They were accompanied by species typical for pelagic waters (e.g. Trichocerca pusilla, T. similis). Bivalves inhabiting outflows of rivers from Knyszyn Forest had the most diversified and abundant epizoic communities. Large differences were also observed as regards particular species occurrence in different habitats. Maximum numbers of Ptygura melicerta living on the surface of bivalves from rivers accounted for 150 individuals per bivalve specimen, whereas those living on animals from lakes - up to 10 individuals. All studied bivalves were colonized by very large numbers of bdelloids.

Epizoic Communities of Prokaryotes on Healthy and Diseased Scleractinian Corals in Lingayen Gulf, Philippines

In search for microbiological indicators of coral health and coral diseases, community profiles of coral-associated epizoic prokaryotes were investigated because of their dual potential as a source of coral pathogens and their antagonists. In pairwise samples of visually healthy and diseased coral specimens from Bolinao Bay (Pangasinan, Philippines), mixed biofilm communities of ectoderm- and mucus-colonizing epizoic prokaryotes were compared using fluorescent in situ hybridization (FISH). Oligonucleotide probes targeted 13 phylotypes representing the main taxonomic groups of marine prokaryotes. Coral taxa tended to show specific community profiles. An attempt to separate the profiles of healthy and diseased specimens by applying principal component analysis (PCA) to a (nonselective) collection of corals (affected by various diseases) proved unsuccessful. On the other hand, separate PCA clusters were obtained from healthy and diseased corals belonging to a single species (Pocillopora damicornis) only. This cluster formation was dominated by principal component 1 with the genus Vibrio accounting for 18%. At the same time, reef-site-specific clusters were formed as well. At a reef site exposed to pollution from intensive fish cage (Chanos chanos) farming, healthy P. damicornis were mainly (93%) colonized by unicellular cyanobacteria. The formal calculation of diversity parameters suggested that evenness in particular was driven by both health status and reef site location. Despite the low resolution of taxonomic levels achieved with FISH probes targeting only large phylotype groups, significant differences between healthy and diseased corals and also between polluted and nonpolluted reef sites were observed.

Invertebrate associations with gastropod shells inhabited by Pagurus­bernhardus (Paguridae) – secondary hard substrate increasing biodiversity­in North Sea soft‐bottom communities

The crustacean Pagurus bernhardus is an abundant hermit crab species in the soft‐bottom benthic communities of the North Sea. The gastropod shells inhabited by the hermit crab were found to provide substrate for a diverse epizoic fauna. In order to describe the epizoan community as well as spatial differences in epizoan communities of the North Sea, hermit crabs were sampled during summer 2001 at five stations in the North Sea. In total, 51 epizoic species with up to 15 species and 427 individuals per crab were found. The most abundant epizoans were obligate associated species such as the polychaete Circeis amoricani paguri, the cnidaria Hydractinia echinata and the crustacean Trypetesa lampas, as well as sessile epizoans also found in hard‐bottom habitats such as balanids Balanus crenatus and Verruca stroemia or free‐living species such as the amphipod Gammaropsis nitida. The epizoic community structure on shells of the stations north of the 50 m contour differs from the southern communities on the Dogger Bank and in the German Bight. The northern stations were dominated by sessile species, whereas a higher proportion of free‐living epizoans occurred at the southern stations. The results are discussed concerning the ecological importance of shells inhabited by hermit crabs as a hard substrate in soft‐bottom habitats.

Unionid Bivalve Influence on Benthic Algal Community Composition in a Michigan Lake

ABSTRACT Algae were sampled from unionid shells and unconsolidated sediments near (~ 0.05 m) and far (~ 1 m) from unionids, in two distinct habitats (~ 8 m deep silty areas and ~ 1 m deep sandy areas) in Douglas Lake, Michigan. Epizoic communities (dominated by Batrachospermum sp., Oscillatoria spp., and Lyngbya sp.) differed markedly from sediment algal communities. Algal communities in the deep, silty habitat differed from those in shallow sandy habitat; Oscillatoria spp. were more common in silt whereas several diatom genera were common in sand. Proximity to unionids did not greatly alter sediment algal community composition. Experimental comparison of algal communities grown on live unionids and non-living shells suggested that a live unionid host increased the relative abundance of Lyngbya sp. but not other common epizoic filaments (e.g., Batrachospermum sp., Oscillatoria spp.).

QUANTITATIVE ANALYSIS OF EPIZOANS ON SILURIAN STROMATOPOROIDS WITHIN THE BRASSFIELD FORMATION

Stromatoporoids from the Brassfield Formation (Early Silurian, Llandovery) near Fairborn, Ohio, provided substrata for a diverse epizoic community. The stromatoporoids were colonized by at least 28 taxa, including bryozoans, cnidarians, echinoderms, annelids, and endolithic organisms. Analysis of the occurrence, diversity, distribution, and coverage of the epizoans recognized patterns of site-selective attachment on the surface of the stromatoporoids.The upper surface of the stromatoporoids had a slightly higher total epizoan coverage than the lower surface. Concentric zones outlined from the margin also had differences in area and percent coverage. On the upper and lower surfaces, epizoan occurrence decreased from the margin to the interior. Epizoan coverage for the lower surface also decreased inward. On the upper surface, the middle zone had the highest coverage followed by the outer and polar zones, respectively. Among the major invertebrate phyla, only the echinoderms were randomly distributed. Bryozoans, cnidarians, and miscellaneous taxa including borers, cornulitids, and spirorbids were distributed nonrandomly on the surface of the stromatoporoids.Over 95 percent of the stromatoporoid area analyzed is not covered by epizoans. However, epizoans are commonly clumped or in direct contact with one another. These physical interactions are the result of site-selective attachment by epizoans in close proximity rather than competition for available space.

Quantitative analysis of epizoans on Silurian stromatoporoids within the Brassfield Formation

Stromatoporoids from the Brassfield Formation (Early Silurian, Llandovery) near Fairborn, Ohio, provided substrata for a diverse epizoic community. The stromatoporoids were colonized by at least 28 taxa, including bryozoans, cnidarians, echinoderms, annelids, and endolithic organisms. Analysis of the occurrence, diversity, distribution, and coverage of the epizoans recognized patterns of site-selective attachment on the surface of the stromatoporoids.The upper surface of the stromatoporoids had a slightly higher total epizoan coverage than the lower surface. Concentric zones outlined from the margin also had differences in area and percent coverage. On the upper and lower surfaces, epizoan occurrence decreased from the margin to the interior. Epizoan coverage for the lower surface also decreased inward. On the upper surface, the middle zone had the highest coverage followed by the outer and polar zones, respectively. Among the major invertebrate phyla, only the echinoderms were randomly distributed. Bryozoans, cnidarians, and miscellaneous taxa including borers, cornulitids, and spirorbids were distributed nonrandomly on the surface of the stromatoporoids.Over 95 percent of the stromatoporoid area analyzed is not covered by epizoans. However, epizoans are commonly clumped or in direct contact with one another. These physical interactions are the result of site-selective attachment by epizoans in close proximity rather than competition for available space.

Amathamide alkaloids in the pycnogonid, Stylopallene longicauda, epizoic on the chemically defended bryozoan, Amathia wilsoni

Amathamides comprise a group of brominated alkaloids found in the bryozoan, Amathia wilsoni Kirkpatrick (Gymnolaemata: Ctenostomata). We tested a crude bryozoan extract and purified amathamide C for their ability to deter feeding by fish, Acanthaluteres spilomelarnurus (Quoy and Gaimard, 1824 ) (Leatherjacket), in laboratory assays. Food pellets made with crude extracts (1 % dry weight) caused 94% inhibition of artificial pellet acceptance, while amathamide C at 0.1 % dry weight caused 86% inhibition. These results suggest amathamides serve as chemical defences of A. wilsoni. Because bryozoans are often colonised by epibionts, we also examined representatives of the epizoic community on A. wilsoni , using gas chromatography! mass spectrometry (GCMS) for the presence of amathamides. Of 34 epizoic species tested, only one, the sea spider Stylopallene longicauda Stock which was present in high average densities, contained amathamides in concentrated amounts even when deprived of food for 36 hours. In view of the demonstrated feeding deterrence of amathamides in bryozoans, the relatively high epizoic density of S. longicauda and its apparent aposematic colouration suggest that amathamides may also function as chemical defences for S. longicauda.

A simple freeze dehydration method for studying epiphytic and epizoic communities using the scanning electron microscope

Freeze dehydration provides instant immobilisation and fixation of living materials to capture particular events and avoids the need for dehydration through an ethanol series for SEM viewing. Examples of the technique are given from freshwater epiphytic and epizoic communities. The species and community architectures found show the great need which exists for the study of the biology of these systems in their natural, undisrupted states.