ReefMedMol: Mollusca from the infralittoral rocky shores - the biocoenosis of photophilic algae - in the Mediterranean Sea.

Abstract Background This paper describes two datasets on the molluscan fauna from the Mediterranean infralittoral reef ecosystem - the biocoenosis of photophilic algae. The ﬁrst dataset is taken from the East Mediterranean node of the NAGISA project. The second one is a compilation based on the available published material in peer - reviewed journals as well as from the accessible grey literature. These datasets cover a time period of 43 years from 1969 to 2012 from several locations spanning the Mediterranean Sea. New information This dataset is the only one available from this important Mediterranean Habitat, coded as 1170 in the Habitats Directive (92/43/EEC) and can provide valuable information on the needs of ecosystems functions and services assessment, habitat and species conservation as well as marine spatial planning.


Introduction
The Mediterranean Sea is the largest enclosed marine environment globally (Coll et al. 2010). A large proportion of its coastline is rocky and mainly made by limestone, a defining characteristic of this marine basin (Gerovasileiou and Voultsiadou 2012). There, marine hard substrates exists which is of great ecological and economic value due to the high structural complexity on which rich marine communities are based. Yet, several goods and services are provided by (Salomidi et al. 2012). Due to the importance of this marine ecosystem, Habitat Directive 92/43/EEC includes it under the code 1170 (Reefs). In the infralittoral zone of the hard substrate, several biocoenoses exist (Pérès and Picard 1964). Among them, the biocoenosis of the photophilic algae is the one that dominates the hard substrates in depths up to 30 meters, depending on the water turbidity, light penetration and availability of nutrients (Coppejans 1980). Macroalgae, the main component of this biocoenosis, provides an excellent host for food and shelter to the taxonomic group of molluscs. This is one of the most important animal groups found in the Mediterranean Sea, and its molluscan fauna is the best known in the world (Sabelli and Taviani 2013) while from the 17,000 marine species that have been found in the Mediterranean, 13% are molluscs (Coll et al. 2010). The biocoenosis of photophilic algae is, however, poorly studied in terms of molluscan biodiversity; few studies examine the species communities in the infralittoral zone. All of them are paper-based, while the detection of them as well as the compilation of the included published information about the species and other associated data (sampling method, depths, location, time period) cannot be retrieved automatically by machine-learning methods and tools.
This study attempts to expand the current knowledge on the rocky infralittoral zone of the Mediterranean Sea by providing occurrence data of molluscan species from two different sources. The first one comes from the sampling campaign of the NAGISA project in the East Mediterranean Sea while the second one comes from the compilation of the available and accessible published material in peer-reviewed journals and grey literature. The present datasets include georeferenced and fully documented information from 22 regions/ sampling sites across the Mediterranean Sea, from 1969 to 2012 (Table 1) on 599 species of molluscs (Table 2). Additional information based on the dataset of the NAGISA project about the recorded individuals per species is alsoincluded (127 species, 10326 individuals).

Project description
Title: This dataset combines the data of two sources: (a) the monitoring of infralittoral rocky shores in Crete in the framework of the NaGISA project (Natural Geography in Shore Areas, http://www.coml.org/projects/natural-geography-shore-areas-nagisa); (b) the collection and indexing of available and accessible paper published material in peer-review journals as well as grey literature sources.

Study area description:
This dataset includes records from 19 sampling sites at 18 different locations (Table 1, Fig. 1).
East Mediterranean NAGISA project data -Alykes and Elounda: Both sampling sites are located on the North coast of Crete (Eastern Mediterranean) and are characterised by a continuous hard bottom habitat with dense algal coverage (Cystoseira spp., Sargassum sp., Corallinales spp.) and a moderate wave exposure. The area of Alykes has on average a denser algal coverage than the area of Elounda. The substrate is dominated by limestone rocks. Neither of the two sites is impacted by detectable anthropogenic activity, though a sandy beach in ca 500 m distance of the sampling area in Elounda is subjected to moderate beach tourism and increased leisure boat traffic in the summer months.

Sampling methods
Study extent: The data covers 2 sampling events under the NaGISA initiative and several independent sampling events over a time period of 45 years . The dataset originates from 18 sampling sites in several countries of the Mediterranean Sea. Samples were collected from the infralittoral zone from a maximum depth of 40 m (in few studies), having a maximum sampling depth of 20m. Concerning the distribution of molluscs, this habitat is understudied in the Mediterranean Sea -in fact, the Ocean Biogeographic Information System contains only 2 datasets regarding the mollusca fauna over hard bottoms for the entire Mediterranean Sea, and neither of these two are from the infralittoral zone. The present dataset thus provides an important addition to the exiting data for this habitat in the region. Samples form the other sites have been collected in different periods over the year or over several years under different frameworks. The published available information contains the sampling methods and only the species list that have consequently found in the studied area.
Quality control: All scientific names were standardized against the World Register of Marine species using the Taxon Match tool (http://www.marinespecies.org/aphia.php? p=match). If recent taxonomic reviews were available that had not been incorporated into WoRMS at the time of standardization, nomenclature follows those reviews.
The present dataset contains the first electronically available quantitative data on the infralittoral molluscs from the Mediterranean Sea. Moreover, it provides the first qualitative information (species list) about the molluscs from the hard substrates -the biocoenosis of photophilic algae -from that region. As for the coralligenous formations of the infralittoral zone, available dataset can be found at http://doi.pangaea.de/10.1594/PANGAEA.847623 (Poursanidis and Koutsoubas 2015).

Taxonomic coverage
Description: The present dataset, after updating the taxonomy, contains distribution records for 599 species (Table 2).
In total, 155 families have been found over the studied biocoenosis.  Number of species and families per sampling location. Diagram based on the data from Suppl. material 2 (Poursanidis and Koutsoubas 2015) where the same percentage of molluscs have been found.
During the last decade, research in several areas in the Mediterranean has shed light on the ecology of these habitats and revealed a vast amount of information on the biodiversity of the biocoenosis of the photophilic algae (Antit and Azzouna. 2012, Antit M. et al. 2013, Antoniadou and Chintiroglou 2007, Antoniadou et al. 2006, Antoniadou et al. 2005, Badalamenti et al. 2002, Chemello and Milazzo 2002, Kasemi et al. 2008, Milazzo et al. 2000, Miloslavich et al. 2013, Pitacco et al. 2014, Sanchez-Moyano et al. 2000, Terlizzi et al. 2005, Terlizzi et al. 2003. The increased research effort on these habitats along with the initiative of the NAGISA project, addresses the need for a better understanding of the role of this important in the coastal marine environment which is under continuus pressures and threats (EEA 2015 The name of the water body in which the sampling location occurs. island The name of the island on or near which the sampling location occurs. country The name of the country on which the sampling location occurs.

municipality
The full, unabbreviated name of the next smaller administrative region than county (city, municipality, etc.) in which the sampling location occurs. locality The exact locality where the sampling procedure took place minimumDepthInMeters The lesser depth of a range of depth below the local surface, in meters.

maximumDepthInMeters
The greater depth of a range of depth below the local surface, in meters.

locationRemarks
The method that the location has been located by using Google Earth app.

Kingdom
The full scientific name of the kingdom in which the taxon is classified.

Phylum
The full scientific name of the phylum in which the taxon is classified.

Class
The full scientific name of the class in which the taxon is classified.

Order
The full scientific name of the order in which the taxon is classified.

Family
The full scientific name of the family in which the taxon is classified.

Genus
The full scientific name of the genus in which the taxon is classified. specificEpithet The full scientific name of the specie in which the taxon is classified.
Data set name: Mollusca fauna from the Mediterranean reef ecosystem (1170) -the zone of the photophilic algae.
Character set: UTF-8 This publication refers to the most recent version of the dataset available through the IPT server. Future changes to the dataset due to quality control activities might change its content or structure.

Source
The literature source used for basisOfRecord The specific nature of the data record, as described in http://rs.tdwg.org/dwc/ terms/type-vocabulary/index.htm. taxonRemarks Comments or notes about the taxon or name.