Benthic communities in three Mediterranean touristic ports: MAPMED project

Abstract Background Mediterranean ports are sources of significant economic activity and at the same time they act as recipients of considerable anthropogenic disturbance and pollution. Polluted and low-in-oxygen sediments can negatively impact benthic biodiversity and favour recruitment of opportunistic or invasive species. Macrobenthic communities are an important component of the port biota and can be used as environmental quality indicators. However, a baseline database for benthic biodiversity in Mediterranean ports has not yet been widely established. New information Macrobenthic assemblages were recorded in three Mediterranean touristic ports under the framework of the ENPI CBC MED project MAPMED (MAnagement of Port Areas in the MEDiterranean Sea Basin). Samples were collected from Cagliari (Sardinia, Italy), Heraklion (Crete, Greece) and El Kantaoui (Tunisia) ports during February, May and September 2012. The sampling stations were selected according to the different sectors within each port (i.e. leisure, fishing, passenger/cargo vessels and shipyard). A total of 277 taxa belonging to 12 phyla were found, of which the 96 taxa were present in all three ports. El Kantaoui port hosted the highest number of macrobenthic taxa. Mollusca were the most abundant group (34%) in all ports. The highest percentage of opportunistic taxa per station was found before the touristic period in the shipyard of Heraklion port (89.3%).


Introduction
Mediterranean ports are sources of significant economic activity and they strongly support local, regional and national economic development. The Mediterranean Sea hosts about 480 ports and terminals and is one of the busiest maritime areas of the world (REMPEC 2008). Shipping of goods between the main EU ports and ports located in the Mediterranean reached 598 million tonnes in 2015 (Eurostat 2015), while crude oil transported through the Mediterranean Sea was 421 million tonnes in 2006 (REMPEC 2008). Ports act as recipients of considerable anthropogenic disturbance and pollution due to the activities they are hosting, such as emission of air pollutants, noise, sediment dredging and transport, industrial installations, wastewater discharges, oil spill accidents, storage and spillage of hazardous materials and introduction of invasive species (Darbra et al. 2005). Polluted marine sediments, commonly low oxygen levels and low hydrodynamism can have a negative impact on benthic biota and marine biodiversity, which may favour recruitment by opportunistic or more resistant taxa, including invasive species. Macrobenthic communities are an important component of the port biota and have been commonly used as environmental quality indicators in biomonitoring studies (Gray and Elliot 2010). Therefore, the establishment of a baseline database for benthic biodiversity in Mediterranean ports can offer valuable background information for port management activities, including the identification of biological risks, such as pollution events or invasion by alien species (Mandal and Harkantra 2013).
Kantaoui (Tunisia) (Chatzinikolaou and Arvanitidis 2017). Sampling was undertaken seasonally during the ENPI CBC MED project MAPMED in 2012 in different sectors within each port, which were defined according to their distinct usage activities (i.e. leisure, fishing, passenger/cargo vessels and shipyard). Samples were collected during winter (February), before the touristic period (May) and after the touristic period (September) in order to identify the impact of seasonal touristic activities on benthic communities. A detailed comparison of macrobenthic biodiversity amongst different locations -sectorsseasons was performed in order to offer information about the environmental quality at these understudied artificial port environments. A total of 277 taxa belonging to 12 phyla were found, of which 96 taxa were common in all ports. Differences in benthic biodiversity were found between ports and between sectors in each port, while seasonal differences were not apparent (Chatzinikolaou et al. 2018). The El Kantaoui port hosted the highest number of macrobenthic taxa, while the shipyard sector in Heraklion port had the lowest number of taxa. The highest abundance of opportunistic taxa was found in Heraklion port at the passenger ships and shipyard stations.

Sampling methods
Sampling description: Five replicates of sediment samples were collected from each station using a box corer (13.5 cm × 13.5 cm × 16 cm) manually operated from a small boat. A Garmin 60 CS portable GPS and a depth meter were available on board to record the exact position and depth of each station respectively. The sediment samples were sieved through a 0.5 mm sieve and then fixed and preserved in 5% formaldehyde buffered with seawater and stained with Rose Bengal. The benthic organisms were sorted out of the sediment under a stereoscope, counted and identified down to the lowest possible taxonomic level.
Quality control: All scientific names were standardised against the World Register of Marine Species using the Taxon Match tool (http://www.marinespecies.org/aphia.php? p=match) on 10-03-2021.

Geographic coverage
Description: Three Mediterranean touristic ports were selected as study sites and they are presented in Fig. 1. The port of Cagliari (Fig. 1B) is a large port (2.07 km ) located on the southern coast of Sardinia (Italy). The port of Heraklion (Fig. 1C) is medium-sized (0.87 km ) and it is located on the northern coast of Crete (Greece). The port of El Kantaoui (Fig. 1D) is a small touristic marina (0.04 km ) on the eastern Tunisian coast. Both the ports of Heraklion and Cagliari host a leisure marina, large passenger, cruise and cargo vessels, while El Kantaoui port offers moorings only for smaller fishing boats, luxury yachts and boats for sporting activities. Heraklion port has also a shipyard section.
Sampling stations were selected in order to achieve good spatial coverage in each port and also to represent sectors with different uses according to the Water Management Units The three Mediterranean touristic ports (A) and location of the sampling stations in Cagliari (B), Heraklion (C) and El Kantaoui (D) in MAPMED Action Plans (MAPMED 2015). Four stations were selected in the port of Heraklion, five stations in the port of Cagliari and three stations in the port of El Kantaoui (Table 1)

Taxonomic coverage
Description: The dataset includes information on macrobenthic assemblages found in the three Mediterranean touristic ports belonging to the following 12 phyla: Annelida, Mollusca, Arthropoda, Echinodermata, Sipuncula, Nemertea, Cnidaria, Phoronida, Chordata, Foraminifera, Platyhelminthes and Priapulida ( A total of 46,187 individuals were identified down to the lowest possible taxonomic level, from which 15,535 were found in Cagliari port, 11,571 in Heraklion port and 19,081 in El Kantaoui port. A total of 277 macrofaunal taxa were identified in the three ports, from which 32 were present exclusively in Cagliari port, 22 were found only in Heraklion port and 53 were found only in El Kantaoui port. A total of 96 taxa were common between all three Mediterranean ports (Fig. 2). The highest number of taxa in total was found in El Kantaoui port (206), while Cagliari and Heraklion ports had 170 and 165 taxa in total, respectively.
The percentage of opportunistic taxa abundances (i.e. short-lived taxa often characterising disturbed or stressed habitats) was calculated for each station as the percentage of abundances for Capitellidae, Cirratulidae, Spionidae and Oligochaeta taxa (Pearson andRosenberg 1978, Munari et al. 2005) in the total sample (Fig. 4). The highest percentages (> 50%) of opportunistic taxa abundances were found in Heraklion port at stations H3 (passenger ships) during all seasons and at H5 (shipyard station) in winter and especially before summer. Additionally, in El Kantaoui station E1 (leisure boats), the percentage of opportunistic taxa abundance increased before summer. The percentage of opportunists in Cagliari was generally lower than in the other ports. Additional statistical analysis has been applied to the species composition matrices of the specific dataset by Chatzinikolaou et al. (2018) and Dimitriou et al. (2020) in order to explore the multivariate patterns of benthic assemblages and to calculate benthic diversity and biotic indices for the assessment of the ecological status of the habitats. A detailed comparison of macrobenthic biodiversity amongst the different locations -sectorsseasons indicated significant differences between ports and between sectors in each port, while seasonal differences were not apparent (Chatzinikolaou et al. 2018).  Percentage (%) of opportunistic taxa abundances in the different stations of Cagliari port (purple: C1, C2, C3, C4 and C5), Heraklion port (orange: H1, H3, H4 and H5) and El Kantaoui (blue: E1, E2 and E3) during the three differerent sampling seasons (dark colours: winter, medium colours: before summer, light colours: after summer).
Notes: Three seasonal sampling campaigns were carried out during 2012: one in winter (February), one in spring before the beginning of the touristic season (May) and one in late summer after the touristic season (September).

Collection data
Collection name: Benthic communities and environmental parameters in three Mediterranean ports (Sardinia, Crete and Tunisia).
Specimen preservation method: 5% formaldehyde buffered with seawater. This publication refers to the most recent version of the dataset available through the IPT server or MedOBIS. Future changes to the dataset due to quality control activities might change its content or structure.
The current publication refers to the "occurrence" source file (txt file) that is associated with the particular dataset. Additional details about the sampling events can be found in the "event" source file (txt file) associated with the same dataset.

Column label Column description
id A unique identifier for the record within the dataset or collection, auto-incrementing number automatically added by the system (same with eventID).  The ellipsoid, geodetic datum or spatial reference system (SRS) upon which the geographic coordinates given in decimalLatitude and decimalLongitude are based.
coordinateUncertaintyInMetres The horizontal distance (in metres) from the given decimalLatitude and decimalLongitude describing the smallest circle containing the whole of the Location.
georeferenceProtocol A description or reference to the methods used to determine the spatial footprint, coordinates and uncertainties. institutionCode The name (or acronym) in use by the institution having custody of the object (s) or information referred to in the record.
collectionCode An identifier for the collection or dataset from which the record was derived. basisOfRecord The specific nature of the data record.
occurrenceID An identifier for the Occurrence (as opposed to a particular digital record of the occurrence).
catalogNumber An identifier (preferably unique) for the record within the dataset or collection. taxonRemarks Comments or notes about the taxon or name in the original dataset file.