BOBECO – SCIENTIFIC BLOG (LEG 1) (English version)

Summary of BOBECO:

Deep corals occur in extreme conditions of low temperature, without light and at depths of 300 to 2000m. Their reefs can reach hundreds of metres in length and tens of metres high, and their structure can host a rich and complex ecosystem which may evolve over some thousands of years. Those fragile ecosystems are nowadays threatened in the short term by human activities, particularly deep-sea fisheries, and on a medium term by ocean acidification linked to global climate change. The EU-funded project CoralFISH aims to study the interactions between corals and fisheries, and to provide the information needed for better management of these ecosystems throughout Europe, from Norway to Italy. An important aspect of the project is to provide classification criteria to protect zones according to international conventions.

The French teams from IFREMER have three cruises focussing on the poorly explored Bay of Biscay andWestern Ireland. The BobGeo cruises (Bay of Biscay –GEOlogy) in 2009 and 2010 allowed the high resolution mapping of 3 zones characterizing canyons and interfluves of theBay of Biscaywhere corals have already been collected. The detailed analysis of the data collected on these cruises has described the geological, sedimentary and hydrological features of the submarine ‘landscapes’ which influence the spatial distribution of corals, and has helped to select targets for the final cruise. This cruise, BobEco (Bay Of Biscay – ECOlogy), hopes to reveal at high resolution the spatial structures of communities in the coral ecosystem, and their genetic, chemical and microbiological features, as well as the occurrence of deep sea fishes. Fisheries impact on coral communities and on their genetic structure will also be estimated.

The scientific survey will also provide invaluable geological information. Chronological data will be extracted from fossil corals in order to better understand the vulnerability of these deep-sea coral systems over time.

In order to achieve the objectives of CoralFISH, study sites have been selected along the Irish continental margin and Bay of Biscay(Figure 1).

Figure 1. BOBECO study sites. Showing sites from Oleron Canyon to Logachev carbonate mound. Yellow sites indicate canyons that have not previously been studied.

The scientific activities undertaken during the BobEco sampling campaign are summarised by various scientists in the daily ‘Scientific Blog’ below.

Norbert Frank

10 – 9 – 2011

RV Pourquoi Pas? departed towards the first sampling site, Guilvinec Canyon. High resolution topographical data was acquired during transit to the canyon. The ship continued on its journey towards designated sites where equipment deployment and ROV [Remotely Operated Vehicle] Victor6000 dives were due to take place.

Norbert Frank

11 – 9 – 2011

The first ROV dive was cancelled due to technical difficulties. Subsequently, deployment of the ADCP (used for measuring current) was postponed, but eventually deployed in Guilvinec Canyon. The benthic lander was also deployed in Guilvinec Canyon in order to observe fish populations associated with coral ecosystems. BOBGEO topographical maps were completed during acquisition of bathymetric data between dives. During the second dive on Guilvinec Canyon, the OTUS camera on the ROV was used to obtain black and white imagery at 10m from the bottom floor. The mechanism behind the ADCP and Lander are shown in Figures 2 and 3.

Figure 2. ADCP used in Guilvinec Canyon.

Figure 3. Benthic lander used to observed fish in coral ecosystems.

Norbert Frank

13 – 9 – 2011

A particle trap previously deposited one year prior to BOBECO was recovered. The trap and its associated ropes were heavily colonized by various sessile invertebrates, such as bryozoans, hydroids and anemones (Figure 4).

Figure 4. Particle trap and its colonizers.

The OTUS camera dive conducted with the ROV was a great success; a large amount of bathymetric data was obtained.

Norbert Frank

14 – 9 – 2011

Transit to Oleron Canyon(Region Bob 3) took place during the night of Sept 13th – 14th. Multibeam data was acquired during transit and the Benne Hamon was deployed.

During ROV dive 465 – 3 in Oleron Canyon, no reef building corals, such as Lophelia pertusa and Madrepora oculata, were observed. However, a scatter of gorgonians and sponges were observed. Coral gardens were observed at the bottom of the transect.

Scientific briefings will begin on Sept 15th. This will allow scientists on board to talk about their research and share information in their particular field of expertise. During the scientific meeting, clarification on sampling strategy and laboratory protocols were established.

Norbert Frank

15 – 9 – 2011

Ars Canyon was observed during an 8 hrs dive that began Sept 14th and ended Sept 15th  (Dive 466 – 4). There were few living organisms observed.

Norbert Frank

16 to 17 – 9 – 2011

The ROV was deployed for the first time in Croizic Canyon(Dive 468-06) in region BOB 2. Initially, we explored the canyon at depths between 1100-840m. Significant reefs were found during the exploratory dive. Trawl marks and fishing gear, such as net and chains, were observed in the coral reef (Figure 5). The trawl marks spanned 16m of area within the reef.

Figure 5. Trawled area (bottom) adjacent to dense coral reef (top). Coral rubble and fishing gear are shown in the bottom frame of the image.

The exploratory dive was followed by a sampling dive. Priority organisms were collected between 840-650 m in designated quadrates overlapping the pre-explored coral habitat. A wide range of samples were collected in order to achieve the aims of the cruise. Systematic collections of L. pertusa, M. oculata and the associated polychaete, Eunice norvegica, were conducted for subsequent genetic, population and microbiology work. The digestion required for DNA extraction was conducted immediately. These were also prepared by team members for later use in radioisotopic chemistry to enable coral dating of both L. pertusa and M. oculata.

Reef-associated fauna was collected for taxonomy. Echinoiderms were collected for Angela, who is studying their gut contents and stable isotope ecology. Sediment and rock samples were also obtained for geological work. Seawater was obtained for microbiology studies. In situ physiological studies were also conducted on M. oculata and L. pertusa with a respiration chamber (CALMAR).
The exploratory dive was followed by a sampling dive. Priority organisms were collected between 840-650 m in designated quadrates overlapping the pre-explored coral habitat. A wide range of samples were collected in order to achieve the aims of the cruise. Systematic collections of L. pertusa, M. oculata and the associated polychaete, Eunice norvegica, were conducted for subsequent genetic, population and microbiology work. The digestion required for DNA extraction was conducted immediately. These were also prepared by team members for later use in radioisotopic chemistry to enable coral dating of both L. pertusa and M. oculata.

Angela Stevenson

17 – 9 – 2011

After a successful dive that kept the team long hours in the lab, Thomas’s Lander was recovered. Unfortunately, the flash settings failed to function during the Lander’s entire deployment and so fish populations could not be observed in the area via the Lander.

Angela Stevenson

18 to 19 – 9 – 2011

Today, an ROV dive was initiated at midnight in Guilvinec Canyon(Dive 469 – 7) in region BOB 2. The aims of this dive were to provide a colour survey to accompany the SMF and MMR OTUS imagery previously obtained on an earlier dive in Guilvinec Canyon. For the next 42hrs, sampling took place in dense reefs separated by sectors containing sediment only. Physiological experiments were again performed in situ. Respiration rates of L. pertusa and M. oculata were measured with the CALMAR chamber. Microbiology samples were obtained to later determine the microbial fauna associated with the observed reef. A standardized transect was performed for habitat mapping to assess invertebrate populations residing in dense coral garden. Target invertebrate species, such as unidentified Antipatharians (black coral); Narella on hard and soft substrate; octocorals; sponges; and echinoids were collected for taxonomic and ecological studies.

For the acquisition of geological data and to better understand the of processes that led to coral reef formation, three Calypso cores were obtained in the coral area. The ADCP, which was deployed on Sept 10th, was recovered successfully and provided invaluable information about salinity, temperature, and currents in the area.

This long dive on Guilvinec Canyon revealed some large and dense coral gardens (Figure 6).

Figure 6. Dense coral garden and associated fauna in Guilvinec Canyon.

Last but not least, many small and under appreciated invertebrates were captured in several photographs. Two of which revealed stunning images (Figures 7 and 8).

Figure 7. Squat lobster and crinoid on coral.

Figure 8. Nudibranch on Madrepora oculata.

Angela Stevenson

20 to 21 – 9 – 2011

An exploration and sampling dive was conducted in Lampaul Canyon (Dive 470-8) in region BOB 1. The primary goal of this dive was to determine the presence of coral and to obtain sediment at various locations on the cliff face in order to help describe geomorphological profiles of the canyon.

The exploratory portion of this dive revealed interesting coral gardens on the canyon wall (Figure 9). Organisms that had not previously been observed during BOBECO were captured and preserved for taxonomic studies. Fourteen hours of the dive were reserved for geological and biological specimen collections. Standardized video imagery of the bottom floor along a transect was captured for the next 12 hrs. This will allow observation and identification of invertebrates residing in the area, which will later be used for habitat mapping.

Figure 9. Invertebrates observed on cliff walls of Lampaul Canyon.

Angela Stevenson

22 – 9 – 2011

RV Pourquoi Pas embarked on a 17 hrs transit back to Brest Harbour with a brief stop in Brest from September 22nd to 24th.  The second leg of the mission was due to start at 7h on Sept 24th.

Angela Stevenson

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