https://ipt.medobis.eu/resource?r=bbl-her Moana Lucia Christ University of Cologne

Cologne 50674 DE

+4915256156805 lucia.moana.christ@gmail.com 0009-0001-2936-2756 Eleni Koumpaki Hellenic Centre for Marine Research Research Technician (MSc)

Gournes Pediados, Crete 71500 GR

e.koumpaki@hcmr.gr 0009-0001-5317-590X Maria Maidanou Hellenic Centre for Marine Research Research Technician (PhD)

Gournes Pediados, Crete 71500 GR

mariam@hcmr.gr 0009-0006-5662-9184 Marin Miletic Energy Institute Hrvoje Pozar

Zagreb 10000 HR

mmiletic@eihp.hr Dimitris Poursanidis Foundation of Research and Technology - Hellas

Heraklion, Crete 70013 GR

dpoursanidis@iacm.forth.gr Sarah Faulwetter University of Patras

Patra 26504 GR

sfaulwetter@upatras.gr Drosos Koutsoubas University of the Aegean

Mytilene 81100 GR

drosos@aegean.gr Christos Arvanitidis LifeWatch ERIC CEO

Seville 41092 ES

ceo@lifewatch.eu Costas Dounas Artificial Reef Innovative Applications Principal Investigator

GR

kdounas@hcmr.gr Panayota Koulouri Hellenic Center for Marine Research Research Director

GR

yol72@hcmr.gr Moana Lucia Christ University of Cologne

Cologne 50674 DE

+4915256156805 lucia.moana.christ@gmail.com 0009-0001-2936-2756 Eleni Koumpaki Hellenic Centre for Marine Research Research Technician (MSc)

Gournes Pediados, Crete 71500 GR

e.koumpaki@hcmr.gr 0009-0001-5317-590X Panayota Koulouri Hellenic Centre for Marine Research Research Director

Gournes Pediados, Crete 71500 GR

yol72@hcmr.gr 0000-0002-3418-7980 Dimitra Mavraki HCMR-IMBBC Data manager

Thalassocosmos, Former American Base Heraklion Crete 71003 GR

dmavraki@hcmr.gr https://imbbc.hcmr.gr/ https://orcid.org/0000-0001-6775-530X custodianSteward 2026-09-02 eng This dataset includes the macrofaunal community composition at the species level of the Benthic Boundary Layer (BBL) of the continental shelf and upper slope of Heraklion Bay, along with its seasonal and bathymetric changes. The study was conducted in spring and autumn of 2001 at depths of 50, 100, 200, and 300 meters, using a hyperbenthic sledge modified to artificially resuspend the sediment surface and simultaneously collect the macrofaunal organisms that reside on or a few centimeters above the seabed. The given diversity data contribute to understanding spatial and temporal trends, while also indicating anthropogenic impacts, e.g., the effects of otter trawling on the BBL macrofaunal communities. BBL macrofauna seasonal trends bathymetric changes continental shelf Mediterranean GBIF Dataset Type Vocabulary: http://rs.gbif.org/vocabulary/gbif/dataset_type_2015-07-10.xml This work is licensed under a Creative Commons Attribution (CC-BY 4.0) License. Creative Commons Attribution 4.0 International https://spdx.org/licenses/CC-BY-4.0.html CC-BY-4.0 A study area of four different stations (St. 1 50, m; St. 2, 100 m; St. 3, 200 m; St. 4, 300 m isobaths) was selected. St. 1, Lat. 35.362000, Lon. 25.1000667; St. 2, Lat. 35.382883, Lon. 25.099350; St. 3, Lat. 35.422783, Lon. 25.094817; St. 4, Lat. 35.444033, Lon. 25.093717). 25.058 25.152 35.455 35.348 2001-02-27 2001-03-03 2001-09-25 2001-09-30 This dataset presents the identified hyperbenthic, (epi-)benthic and planktonic macrofaunal species belonging to the taxonomic groups of Crustacea, Polychaeta and Mollusca and their abundances in the different sampling periods and stations. class Bivalvia class Cephalopoda class Gastropoda class Malacostraca class Polychaeta class Pycnogonida class Scaphopoda The purpose of this study is to fill the gaps regarding macrofauna of the Benthic Boundary Layer (BBL) of the continental shelf and upper slope of Heraklion Bay. The dynamic zone between the sediment surface and the water above the surface, also known as the Benthic Boundary Layer (BBL), can be a few centimeters or tens of meters, depending on different physical and biogeochemical processes (Boudreau and Jørgensen, 2001). According to Dauvin and Vallet (2006), the BBL includes mostly macrofaunal organisms classified in different groups depending on their mobility and bottom dependence: (i) permanent swimmers throughout the water column, (ii) temporary swimmers throughout the water column, (iii) permanent swimmers only in the BBL, (iv) burrowers/swimmers, (v) burrowers and temporary nuptial swimmers, (vi) benthic mobile species, (vii) benthic drift species and (viii) fishes. Their importance for the food web is rooted in first that many of them feed on a broad diversity of prey taxa (e.g. organic and detritus particles and associated microbes, meiobenthos, plankton) and second they form an important food source for benthic and benthopelagic fishes (Mees and Jones 1997; Papiol et al. 2013; Koulouri et al. 2015).However, this particular macrofauna is being underestimated mostly due to technical difficulties of the hyperbenthic sledges applied for collecting these organisms during sampling of the water layer above the seabed in order to avoid contamination with sediment (Eleftheriou 2013). Therefore, Koulouri et al. (2003) modified a hyperbenthic sledge to a towed trawl simulator sledge (TTSS2) to artificially resuspend the sediment surface and simultaneously collect the macrofaunal organisms which actually reside on or a few cm above the seabed.Development of this modified sledge was part of a project focusing on the study of BBL macrofaunal communities as well as relevant biogeochemical parameters in the continental shelf of the oligotrophic Cretan Sea (Dounas 2006; Dounas et al. 2002; 2005; 2007; Koulouri et al. 2003; 2005; 2009; 2013; 2015). The present study is part of this project and its objective is to record the BBL macrofaunal community including certain taxonomic groups (e.g. crustaceans, polychaets, molluscs) and their seasonal and bathymetric changes. The dataset consists of two data files structured in Darwin Core Archive format. The "event" source file (.txt file) provides details about the seven sampling events. In the "occurrence" source file (.txt file) the taxa found in these samples and their densities (ind 100m-2) are listed. This work was carried out in the framework of the project "Development of a new method for the quantitative measurement of the effects of otter trawling on benthic nutrient fluxes and sediment biogeochemistry", financed by the European Commission (DG XIV, Studies for the Support of the Common Fisheries Policy). The present resource was developed within the framework of MARBEFES – MARine Biodiversity and Ecosystem Functioning leading to Ecosystem Services, funded by the European Union's Horizon Europe Research and Innovation Programme under Grant Agreement No. 101060937. The creators would also like to thank the MedOBIS team for hosting the data and assisting with data management.  notPlanned Panayota Koulouri Hellenic Centre for Marine Research Research Director

Gournes Pediados, Crete 71500 GR

yol72@hcmr.gr 0000-0002-3418-7980 1. Two field surveys were carried out in early spring and early autumn. During daylight hours, three tows with 50 m length were performed at station 1 and one tow of 200 m length at stations 2,3 and 4. St. 4 was only sampled in early autumn. Samples were fixed in 10% formalin after collection. 2. The macrofauna was sorted out, classified to the major taxa and counted. Furthermore, the taxonomic groups (Crustacea, Polychaeta ,Mollusca) were identified to the lowest possible taxon level and counted. Macrofaunal densities from the three replicates from station 1 were averaged. Then, all densities estimated in the samples were standardized to the number of individuals per 100 m2 of sediment surface. 3. The data were standardized according to the FAIR principles (Findable, Accessible, Interoperable and Reusable) (Wilkinson MD. et al. 2016). To secure interoperability, the dataset was formatted according to Darwin Core Archive (Wieczorek et al. 2012). For scientific valid names, the World Register of Marine Species with its Taxon Match Tool (WoRMS Editorial Board 2026) was used and the additional measurements and associated facts were standardized with controlled terms from the NERC Vocabulary Server, enhancing interoperability across marine data repositories (BODC - British Oceanographic Data Centre 2026). In the end the dataset was tested using the LifeWatch & EMODnet Biology Quality Control tool (Perez et al. 2024). Two field surveys were conducted on 27 February - 3 March (early spring) and 25 - 30 September (early autumn) 2001 on the continental shelf and upper slope of Heraklion Bay. Sampling was carried out in four isobaths (St.1, St. 2, St. 3, St. 4) at depths of 50,100, 200 and 300 m. Sampling at st. 4 was carried out only in early autumn. As sampling apparatus, a modified hyperbenthic sledge Towed Trawl Simulator Sledge version 2, TTSS2) described in Koulouri et al. (2003), was used simulating the artificial resuspension of the sediment surface (total surface area of 0.45 m2, plankton nets with 0.5 mm mesh size). The sledge was towed from the research vessel “PHILIA” of the Hellenic Centre for Marine Research at a speed of two knots and with a length of wire paid out to depth ratio of 2:1. At station 1 (50 m isobath), three 50 m length tows were performed, while at each of the stations 2 (100 m isobath), 3 (200 m isobath) and 4 (300 m isobath), one 200 m length tow was carried out. Travelling distance of the sledge, while in contact with the seabed, was measured by an odometer and the whole process was monitored by a video-camera, both attached to the apparatus. On board, the samples were preserved in 10% formalin and sorted under a magnifying glass back in the laboratory. Furthermore, the macrofaunal organisms were identified to the lowest possible taxonomic level and counted using a stereoscope and a microscope. 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) on 21-01-2026. Panayota Koulouri 0000-0002-3418-7980 This work was carried out in the framework of the project "Development of a new method for the quantitative measurement of the effects of otter trawling on benthic nutrient fluxes and sediment biogeochemistry" financed by the European Commission (DG. XIV, Studies for the support of CFP). 2026-09-02T09:33:14.684+00:00 dataset Christ M L, Koumpaki E, Maidanou M, Miletic M, Poursanidis D, Faulwetter S, Koutsoubas D, Arvanitidis C, Dounas C, Koulouri P (2026). Benthic Boundary Layer (BBL) macrofauna of the continental shelf of Heraklion Bay (2001). Version 1.0. Hellenic Center for Marine Research. Samplingevent dataset. https://ipt.medobis.eu/resource?r=bbl-her&v=1.0 Benthic Boundary Layer (BBL) macrofauna of the continental shelf of Heraklion Bay (2001) formalin