Echinoderms occurence in a strongly contaminated Bay (Portman, Spain), using ROV and Scuba-diving surveys

Study Extent

The sampling campain was conducted from the 17 to the 24 october 2013, and each sampling event was performed between 10 am and 5pm. Only shallow water ecosystems were sampled (<25m depth). Two sets of sampling stations were determined in order to describe the contamination gradient patterns (1) within the bay of Portman and (2) along a section of the adjacent North-East shoreline. 1: 7 Stations were determined within the bay. The initial principle was to operate two parallel transects starting from the shoreline (the presumed source of contamination)and heading seaward. 2. 6 others samling stations were placed alongside the shoreline for about 1.4 km long. Only The North-Eastern coast side, following the main current, has been sampled. For the data publication process, new events have been generated to store the ad Hoc observations made during the sampling campain.

Sampling

Each sampling station was reached by pneumatic boat (Zodiac MK2 Virage). The first step was to record station relative data ; - WGS84 Coordinates (using a hand GPS Garmin Dakota© 20) - Sea Surface Temperature. In a second time, the following samples were collected by divers ; - 50mL Falcons were filled with sediments, waiting the return to the laboratory for the separation of the finest granulometric fraction (<63µm size) and the H.M content analysis. The metal content analysis methods and results (average of 3 replicates) are detailled in the Measurement Or Facts extension for both the total and the finest fractions. - Water samples for pH and salinity determination. - Specimens : Echinoderms were preserved into ethanol (80%) and stored into the marine biology labs under the collection name 'ULB P'. Each specimen that could belong to a potentially distinct species was collected. The collection was used as a material basis for the identification and as a reference for the imagery based recognition. In another hand, sea urchins (Paracentrotus lividus, Arbacia lixula) and some algae samples were preserved for comparative studies on acid-base physiology and microbial community structures. The last step was the realisation of high resolution video transects, using a micro-ROV (VideoRay pro 3 XE GTO) equipped with an additional HD camera (GOPRO 3 HERO). Straight transects (N,S,E and O) were performed from the georeferenced point to the maximum ROV range (75 meters), respecting a maximum effort of 30 minutes per station.

Quality Control

Some images extracted from the videos recordings and used as a basis for the observation records have been shared on the following web page : http://biomar.ulb.ac.be/portman-rov-sampling-gallery/ The shared pictures only concern uncertain or incomplete identifications and are open to comments (corrections and new observations).

Method steps

1. Each video sample has been carefully viewed. Sure identifications were directly recorded in a spreadsheet, and all uncertain observations were previously extracted to the jpeg format using Avidemux software (V2.6.8). Finally, all data were stored into a spatialised database (MySQL), for their verification and their re-organisation under a Darwin Core schema.

All marine organisms that could be indentified were recorded. Thus the dataset countains different marine phyla. Nevertheless, the sampling methods and identification efforts prioritized echinoderms (Echinodermata) and the majority of the occurrences belongs to this phylum.

1. Animalia
   common name: Animals rank: kingdom
2. Plantae
   common name: plants rank: kingdom
3. Echinodermata
   common name: Echinoderms rank: phylum

Portman Bay and adjacent North-Estern shoreline (Approximately 1.4 kilometer section). Only shallows (depth<25 meters) were sampled.