Data Paper
Data Paper
Epiphytic bryozoans on Neptune grass – a sample-based data set
expand article infoGilles Lepoint, André Heughebaert§, Loïc N. Michel
‡ Laboratory of Oceanology, MARE Centre, University of Liege, Liege, Belgium
§ Belgian Biodiversity Platform, Bruxelles, Belgium
Open Access



The seagrass Posidonia oceanica L. Delile, commonly known as Neptune grass, is an endemic species of the Mediterranean Sea. It hosts a distinctive and diverse epiphytic community, dominated by various macroalgal and animal organisms. Mediterranean bryozoans have been extensively studied but quantitative data assessing temporal and spatial variability have rarely been documented. In Lepoint et al. (2014a, b) occurrence and abundance data of epiphytic bryozoan communities on leaves of P. oceanica inhabiting Revellata Bay (Corsica, Mediterranean Sea) were reported and trophic ecology of Electra posidoniae Gautier assessed.

New information

Here, metadata information is provided on the data set discussed in Lepoint et al. (2014a) and published on the GBIF portal as a sampling-event data set:

The data set is enriched by data concerning species settled on Posidonia scales (dead petiole of Posidonia leaves, remaining after limb abscission).


Epiphytism, biofouling, seagrass, Bryozoa, biodiversity, sample-based data set, ecological traits, Mediterranean Sea


In the marine environment, the term “epiphyte” is defined as: “all micro- or macro-organism living attached on a plant substrate” (Steel and Bastow Wilson 2003). The seagrass Posidonia oceanica L. Delile, commonly known as Neptune grass, is an endemic species of the Mediterranean Sea that hosts a distinctive and diverse epiphytic community, dominated by various macroalgal and animal organisms (Boero et al. 1985; Mazzella et al. 1989; Peres and Picard 1964; Van Der Ben 1971). Among epiphytic animals fixed on seagrass substrates, cheilostome bryozoans are often the most abundant and diverse taxa (Balata et al. 2007; Lepoint et al. 1999; Nesti et al. 2009; Pardi et al. 2006). Some species, like Electra posidoniae Gautier, are strictly found on Neptune grass leaves (Gautier 1961; Lepoint et al. 2014b; Matricardi et al. 1991). Due to this important contribution, cheilostome bryozoan diversity has received particular attention (Balduzzi et al. 1983; Gautier 1961; Harmelin 1973; Hayward 1975; Kocak et al. 2002; Lepoint et al. 2014a), but quantitative data are often lacking and seasonal variability is less often documented than spatial variability. This spatio-temporal variability was assessed quantitatively in Lepoint et al. (2014a) and the occurrence and abundance data set resulting from this study was made freely available on the GBIF portal as a sample-based data set. Biological and ecological features of the leaves’ community are also presented and discussed in Lepoint et al. (2014a). Trophic ecology of Electra posidoniae, an obligate epiphyte of P. oceanica, are discussed in Lepoint et al. (2014b). Scale community data were only published in the GBIF data set but not discussed.

General description of the dataset

The data set is a sample-based data set (n = 103 sampling events), recording occurrence (n = 1234) and abundance of cheilostome Bryozoa (n = 6488 counted colonies) settled as epiphytes on leaves and scales of the seagrass P. oceanica. Sampling encompasses an entire annual cycle (from November 2002 to December 2003) (n = 5 sampling seasons) and six sampling depths (7, 10, 15, 20, 25, 30 m). The data set package is composed of two data files: the former describing sampling events and the latter reporting occurrence and abundance of bryozoan colonies.

Project description

The data were collected during a postdoctoral project (G.L.) entitled: ”Nitrogen dynamics and ecology of the epiphyte community in a Posidonia oceanica seagrass bed”.

The Posidonia seagrass beds are one of the most important ecosystems in the Mediterranean coastal zone. Seagrass beds are in regression in many areas of the world, while the reasons of such regression are complex and often poorly understood. The epiphyte community constitutes an important component of the seagrass meadow. Variability in epiphyte community composition and/or biomass may sometimes be linked to anthropogenic disturbance and used as monitoring tool (Mabrouk et al. 2013; Martinez-Crego et al. 2010; Piazzi et al. 2004). This argues for more fundamental studies of the seagrass ecosystem functioning and epiphyte biodiversity.

The general objective of this project was to study the dynamics of nitrogen in the epiphyte community of the Posidonia leaves in relation with its ecology and its spatio-temporal structure.

Sampling and experiments were performed in Revellata Bay (Corsica, France), near the STARESO oceanographic station between 2002 and 2004. Samples were taken at a reference site (depth 10 m) followed by our laboratory since the 1970s, as well as along a permanent transect (7 to 35 m depth). At the level of a Posidonia shoot, particular attention was given to the spatio-temporal evolution of the structure of the epiphytic community. Specific composition of sessile fauna (mainly Bryozoa) was established at 7, 10, 15, 20, 25 and 30 m depth (Lepoint et al. 2014a). Temporal dynamics and trophic ecology of the dominant species Electra posidoniae was studied using seasonal sampling and isotopic approach (Lepoint et al. 2014b). Finally, we have measured experimentally the nitrogen uptake by different epiphytic macroalgae components (Lepoint et al. 2007). Complementary information about the epiphytic community of P. oceanica in Revellata Bay may be also found in, for example, Dalla Via et al. 1998; Jacquemart and Demoulin 2006; Lepoint et al. 1999; Michel et al. 2015; Pête et al. 2015.

Sampling methods

Study extent

All sampling events (n = 103) and measurements were performed in Revellata Bay (Calvi, Corsica, France), near the marine research centre of STARESO (42°35'N, °43'E) (University of Liège) along the same permanent transects. Sampling encompassed one complete seasonal cycle and the 7 to 30 m depth range occupied by P. oceanica shoots in Revellata Bay (see above).

Sampling description

Seagrass shoots were collected in triplicate in November 2002, March, June, September and November 2003 along the same permanent transects set at 7, 10, 15, 20, 25 and 30 m depth. Each sample is constituted of a single replicate gathering three shoots of P. oceanica.

Quality control

To determine sample size, previous work was performed to determine the number of shoots that accumulates at least the 75% of the leaf epiphyte bryozoan species. For publication on GBIF portal, synonymies were matched against the authoritative, expert-driven World Register of Marine Species (WoRMS) and corrected compared to Lepoint et al. (2014a).

Step description

The shoots were immediately frozen, then conserved in 4% formalin diluted in seawater. Identifications of species settled on leaves and scales (i.e. dead petioles remaining after leaf abscission) under a stereomicroscope (Stemi 2000, Zeiss) were done to the lowest systematic level using keys for Bryozoa (Prenant and Bobin 1966; Zabala and Maluquer 1988), and the works of Balduzzi et al. (1991), Gautier (1961) and Hayward and McKinney (2002). Colonies on scales were not counted and data are presented only as occurrence. All the colonies found on the two sides of leaves were counted. Colonies counted were reported per shoot and per metre square, accounting the average P. oceanica shoot number per metre square, measured at each sampling depth. This parameter was measured monthly using a quadrate with an area of 0.1 m2 randomly set in the meadow. The shoot density did not show any significant variation during the duration of this study. Bathymetric variability of this parameter in Revellata Bay may be found in Gobert et al. (2003).

Geographic coverage


Revellata Bay is a part of Calvi Bay and lies in the western Mediterranean, on the northwestern coast of Corsica (42°35'N, 8°45'E). Its western limit is Punta Revellata Cape, and its eastern limit is Punta San Francesco Cape. The STARESO (STAtion de REcherches Sous-marines et Océanographiques) research station (University of Liège) is located on Punta Revellata, at the western border of the bay. Salinity of the water of Calvi Bay is approximately 38‰, and is relatively invariant throughout the year. Temperature of water varies between minima of 12°C (February) and maxima of 26°C (August), with a notable vertical thermal stratification from May to September. Amplitude of tidal variation is weak. Nutrient concentrations (N, P) and particle load in the water column are typically low and characteristic of oligotrophic areas (Lepoint et al. 2004). Posidonia oceanica meadows cover approximately 50% of the area of the bay, and reach depths of nearly 40 m. Meadows show, in most places, a continuous extension, but local erosion (“intermattes”) occurs (Abadie et al. 2015). The vast majority of meadows grow on soft bottoms, but they seldom colonize rocky substrates. Meadows of Calvi Bay are relatively dense, and show an important foliar biomass and production despite the oligotrophic character of the area (Gobert et al. 2003).


Latitude between 42.5799 and 42.5801; longitude between 8.7285 and 8.7245.

Taxonomic coverage


The dataset includes 54 species of cheilostome Bryozoa, belonging to 25 different families.

Taxa included

A full list of taxa included in this dataset is given in Table 1.

List of taxa included in the dataset.

Rank Scientific name
Kingdom Animalia
Phylum Bryozoa
Class Gymnolaemata
Order Cheilostomatida
Family Aeteidae, Beaniidae, Bitectiporidae, Calloporidae, Candidae, Celleporidae, Chlidoniidae, Chorizoporidae, Cribrilinidae, Electridae, Epistomiidae, Escharinidae, Exochellidae, Flustridae, Haplopomidae, Lacernidae, Margarettidae, Microporellidae, Phidoloporidae, Romancheinidae, Savignyellidae, Schizoporellidae, Smittinidae, Umbonulidae, Watersiporidae
Species Aetea lepadiformis, Aetea truncata, Arthropoma cecilii, Beania hirtissima, Beania mirabilis, Beania robusta, Caberea boryi, Callopora lineata, Cellepora pumicosa, Celleporina caliciformis, Celleporina caminata, Celleporina decipiens, Chartella papyrea, Chlidonia pyriformis, Chorizopora brongniartii, Collarina balzaci, Copidozoum tenuirostre, Cradoscrupocellaria reptans, Electra posidoniae, Escharella rylandi, Escharina vulgaris, Escharoides coccinea, Escharoides mamillata, Fenestrulina joannae, Fenestrulina malusii, Figularia figularis, Haplopoma graniferum, Haplopoma impressum, Hincksina flustroides, Margaretta cereoides, Membraniporella nitida, Microporella ciliata, Parasmittina raigii, Parasmittina tropica, Prenantia cheilostoma, Puellina gattyae, Puellina hincksi, Puellina innominata, Puellina pedunculata, Savignyella lafontii, Schizobrachiella sanguinea, Schizomavella (Calvetomavella) discoidea, Schizomavella (Schizomavella) auriculata, Schizomavella (Schizomavella) cornuta, Schizomavella (Schizomavella) hastata, Schizoporella dunkeri, Schizotheca fissa, Scrupocellaria aegeensis, Scrupocellaria delilii, Scrupocellaria scrupea, Scrupocellaria scruposa, Synnotum aegyptiacum, Turbicellepora magnicostata, Umbonula ovicellata, Watersipora cucullata

Temporal coverage

Data range

01 Nov 2002 – 31 Dec 2003.

Usage rights

This dataset is under a Creative Commons Public domain CC0 license.

Data resources

Data package title:

Epiphytic Bryozoa of Posidonia oceanica leaves and scales. v1.0

Resource link:

Alternative identifiers: doi: 10.15468/78vsgm

Data format: Darwin Core Archive

Data set version: 1.0

Data set description

Number of data files in the data set: 2

File 1 name: event.txt

Data format: CSV

Description: This file gathers data concerning sampling events (n= 103) (12 columns, 104 lines) (Table 2)

Structure of the sampling events file.

Column label Column description
eventID Identification of the sampling event (n=103) (this key is used in the occurrence/abundance file (see below)
eventDate Sampling event date
locationID Sampling time (not location) identification number (n=5)
samplingSizeValue Sampling area (in m2) used to measure the number of P. oceanica shoots per metre square. This value was used to express our abundance data in number of colony per metre square.
sampleSizeUnit Unit used to express abundance (number of colony per metre square)
minimumDepthInMeters Depth of sampling locations (metres)
decimalLatitude Latitude of sampling location (decimal)
decimalLongitude Longitude of sampling location (decimal)
waterBody Name of sampled water area (Revellata Bay, Mediterranean Sea)
locality Name of sampled locality (Calvi, Corsica, France)
countryCode International code of country
samplingProtocol Url link to the web site (open repository of Liège University) to access the original paper explaining the protocol used to obtain this data set

File 2 name: occurrence.txt

Data format: CSV

Description: This file gathers occurrence data (n = 1234) (14 columns, 1235 lines) and is linked to file 1 by event identifiers (eventID column) (Table 3).

Structure of the occurrence/abundance file.

Column label Column description
occurrenceID Identification of the occurrence
eventID Identification number of sampling event (cf. sampling events file, Table 2)
scientificName Binominal scientific name
tKingdom Kingdom of the occurrence
tPhylum Phylum of the occurrence
tClass Class of the occurrence
tOrder Order of the occurrence
tFamily Family of the occurrence
taxonRank Taxon rank of the occurrence
occurrenceStatus Occurrence status (presence/absence)
occurrenceRemarks Localisation of the colony on the plant (on seagrass leaf or on seagrass scales)
organismQuantity number of colonies per square metre
organismQuantityType Nature of counted items (colonies for all species)
dynamicProperties Remarks/number of ovicellated colonies

Author contributions

GL conceived the sampling design, performed the sampling and performed identification of specimens. LNM and AH formatted and published the dataset. LNM, GL & AH wrote the paper.


We sincerely thank the staff of the oceanographic station STARESO (Calvi, Corsica) for their welcome and their logistic help, and particularly Sylvain Plaza for his diving assistance. We acknowledge Björn Berning who reviewed this ms and made valuable recommendations. G.L. is presently Research Associate at Fonds National de la Recherche Scientifique (FRS-FNRS), and benefited during this study of a postdoctoral fellowship from FRS-FNRS. This study was financed by a FRS-FNRS contract (FRFC and the Action de Recherche Concertée 10/533 (French-speaking Community of Belgium). We also warmly thank the Belgian Biodiversity Platform (BELSPO, Belgium) that convinced and formed us to valorise and share such data set for biodiversity study purpose. This paper is MARE paper number 325.


  • Abadie A, Gobert S, Bonacorsi M, Lejeune P, Pergent G, Pergent-Martini C (2015) Marine space ecology and seagrasses. Does patch type matter in Posidonia oceanica seascapes? Ecological Indicators 57: 435–446. doi: 10.1016/j.ecolind.2015.05.020
  • Balata D, Nesti U, Piazzi L, Cinelli F (2007) Patterns of spatial variability of seagrass epiphytes in the north-west Mediterranean Sea. Marine Biology 151: 2025–2035. doi: 10.1007/s00227-006-0559-y
  • Balduzzi A, Barbieri M, Gobetto F (1983) Distribution des bryozoaires gymnolèmes en deux herbiers de posidonies italiens. Analyse des correspondances. Rapports Réunion Commission internationale Exploration Scientifique Mer Méditerrannée 28: 137–138
  • Balduzzi A, Barbieri M, Gristina M (1991) Morphology and life strategies of Aetea (Bryozoa, Cheilostomata) living on some western Mediterranean Posidonia oceanica meadows. In: Bigey FP, d’Hondt J-L (Ed.) Bryozoaires Actuels et Fossiles: Bryozoa Living and Fossil. Societe des Sciences Naturelles de l’Ouest de la France, Nantes, 1–12.
  • Boero F, Chessa L, Chimenz C, Fresi E (1985) The zonation of epiphytic hydroids on the leaves of some Posidonia oceanica (L.) Delile beds in the central Mediterranean. Marine Ecology 6: 27–33. doi: 10.1111/j.1439-0485.1985.tb00318.x
  • Dalla Via J, Sturmbauer C, Schonweger G, Sotz E, Mathekowitsch S, Stifter M, Rieger R (1998) Light gradients and meadow structure in Posidonia oceanica: ecomorphological and functional correlates. Marine Ecology-Progress Series 163: 267–278. doi: 10.3354/meps163267
  • Gautier YV (1961) Recherches écologiques sur les bryozoaires Chilostomes en Méditerrannée occidentale. PhD, Marseilles, Marseilles.
  • Gobert S, Kyramarios M, Lepoint G, Pergent-Martini C, Bouquegneau JM (2003) Variations at different spatial scales of Posidonia oceanica (L.) Delile beds; effects on the physico-chemical parameters of the sediment. Oceanologica Acta 26: 199–207. doi: 10.1016/s0399-1784(02)00009-9
  • Harmelin J-G (1973) Bryozoaires de l’herbier de Posidonies de l’Île de Port-Cros. Rapports Réunion Commission internationale Exploration Scientifique Mer Méditerranée 21: 675–677.
  • Hayward PJ (1975) Observations on the bryozoan epiphytes of Posidonia oceanica from the island of Chios (Aegean Sea). In: Pouyet S (Ed.) Bryozoa 1974. Université Claude Bernard, Lyon, 347–356.
  • Jacquemart J, Demoulin V (2006) Inventory of the epiphytic macroalgae growing on Posidonia oceanica (L.) Delile leaves in the Revellata Bay (Calvi, Corsica). Lejeunia 2006: 1–37.
  • Kocak F, Balduzzi A, Benli HA (2002) Epiphytic bryozoan community of Posidonia oceanica (L.) Delile meadow in the northern Cyprus (Eastern Mediterranean). Indian Journal of Marine Sciences 31: 235–238.
  • Lepoint G, Balancier B, Gobert S (2014a) Seasonal and depth-related biodiversity of leaf epiphytic Cheilostome Bryozoa in a Mediterranean Posidonia oceanica meadow. Cahiers De Biologie Marine 55: 57–67.
  • Lepoint G, Gobert S, Dauby P, Bouquegneau JM (2004) Contributions of benthic and planktonic primary producers to nitrate and ammonium uptake fluxes in a nutrient-poor shallow coastal area (Corsica, NW Mediterranean). Journal of Experimental Marine Biology and Ecology 302: 107–122. doi: 10.1016/j.jembe.2003.10.005
  • Lepoint G, Havelange S, Gobert S, Bouquegneau JM (1999) Fauna vs flora contribution to the leaf epiphytes biomass in a Posidonia oceanica seagrass bed (Revellata Bay, Corsica). Hydrobiologia 394: 63–67. doi: 10.1023/a:1003557303904
  • Lepoint G, Jacquemart J, Bouquegneau JM, Demoulin V, Gobert S (2007) Field measurements of inorganic nitrogen uptake by epiflora components of the seagrass Posidonia oceanica (Monocotyledons, Posidoniaceae). Journal of Phycology 43: 208–218. doi: 10.1111/j.1529-8817.2007.00322.x
  • Lepoint G, Mouchette O, Pelaprat C, Gobert S (2014b) An ecological study of Electra posidoniae Gautier, 1954 (Cheilostomata, Anasca), a bryozoan epiphyte found solely on the seagrass Posidonia oceanica (L.) Delile, 1813. Belgian Journal of Zoology 144: 51–63.
  • Mabrouk L, Hamza A, Brahim MB, Bradai MN (2013) Variability in the structure of epiphyte assemblages on leaves and rhizomes of Posidonia oceanica in relation to human disturbances in a seagrass meadow off Tunisia. Aquatic Botany 108: 33–40. doi: 10.1016/j.aquabot.2013.03.002
  • Martinez-Crego B, Prado P, Alcoverro T, Romero J (2010) Composition of epiphytic leaf community of Posidonia oceanica as a tool for environmental biomonitoring. Estuarine Coastal and Shelf Science 88: 199–208. doi: 10.1016/j.ecss.2010.03.026
  • Matricardi G, Montagna P, Pisano E (1991) Settlement and growth strategies of Electra posidoniae Gautier on Posidonia oceanica (L.) Delile. In: Bigey FP (Ed.) Bryozoaires actuels et fossiles: Bryozoa living and fossil. Nantes, 255–262.
  • Mazzella L, Scipione MB, Buia MC (1989) Spatio-temporal distribution of algal and animal communities in a Posidonia oceanica meadow. Marine Ecology-Pubblicazioni Della Stazione Zoologica Di Napoli I 10: 107–129. doi: 10.1111/j.1439-0485.1989.tb00069.x
  • Michel LN, Dauby P, Dupont A, Gobert S, Lepoint G (2015) Selective top-down control of epiphytic biomass by amphipods from Posidonia oceanica meadows: Implications for ecosystem functioning. Belgian Journal of Zoology 145: 83–93.
  • Nesti U, Piazzi L, Balata D (2009) Variability in the structure of epiphytic assemblages of the Mediterranean seagrass Posidonia oceanica in relation to depth. Marine Ecology-an Evolutionary Perspective 30: 276–287. doi: 10.1111/j.1439-0485.2008.00275.x
  • Pardi G, Piazzi L, Balata D, Papi I, Cinelli F, Benedetti-Cecchi L (2006) Spatial variability of Posidonia oceanica (L.) Delile epiphytes around the mainland and the islands of Sicily (Mediterranean Sea). Marine Ecology-an Evolutionary Perspective 27: 397–403. doi: 10.1111/j.1439-0485.2006.00099.x
  • Peres J-M, Picard J (1964) Nouveau manuel de bionomie benthique de la mer Méditerranée. Edition revue et augmentée. Station Marine d’Endoume, Marseille, 137 pp.
  • Pête DC, Lepoint G, Bouquegneau JM, Gobert S (2015) Early colonization on Artificial Seagrass Units and on Posidonia oceanica (L.) delile leaves. Belgian Journal of Zoology 145: 59–68.
  • Piazzi L, Balata D, Cinelli F, Benedetti-Cecchi L (2004) Patterns of spatial variability in epiphytes of Posidonia oceanica – Differences between a disturbed and two reference locations. Aquatic Botany 79: 345–356. doi: 10.1016/j.aquabot.2004.05.006
  • Prenant M, Bobin G (1966) Bryozoaires: Chilostomes Anasca. Fédération Française des Sociétés de Sciences Naturelles, Paris, 643 pp.
  • Steel JB, Bastow Wilson J (2003) Which is the phyte in Epiphyte? Folia Geobotanica 38: 97–99. doi: 10.1007/BF02803129
  • Van Der Ben D (1971) Les épiphytes des feuilles de Posidonia oceanica Delile sur les côtes françaises de la Méditerranée. Mémoires de l’Institut Royal des Sciences Naturelles de Belgique 168: 1–101.
  • Zabala M, Maluquer P (1988) Illustrated keys for the classification of Mediterranean Bryozoa. Ajuntament de Barcelona, Barcelona, 294 pp.