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Rockall Haddock Survey

Marine Scotland Blog - Mon, 2019-09-16 10:00

MRV Scotia
Survey: 1319S Programme – Rockall Haddock Survey

Duration: 14-26 September 2019

Fishing Gear:

GOV (Grand Overture Verticale) Trawl (BT 137) with ground gear D

Other Gear:

CTD (Conductivity Temperature Depth)  – Seabird 19+
Van Veen Grab

Objectives:
  • Undertake a bottom trawl survey of haddock on Rockall Bank to a depth of 350 m.
  • Deploy a CTD at selected trawl stations to collect temperature and salinity profiles.
  • Collect sediment samples at selected stations.
  • Record marine litter at each trawl station for MSFD (Marine Strategy Framework Directive).
Procedure:

The primary objective of this survey is to assess the state of the haddock stock on the Rockall Plateau. The Rockall haddock survey utilises a semi-random stratified survey design comprising four depth-separated sampling strata. Sampling intensity within each of the four strata reflects the fish density observed in each of these during previous surveys.

Trawling will be carried out during the hours of daylight at randomly selected locations within the 350 m contour. Forty primary tow positions have been generated and their allocation within each depth stratum is displayed in Figure 1.

The number of primary stations within each depth strata is as follows: five stations at 0-150 m, 21 stations at 150-200 m, 10 stations at 200-250 m and four stations at 250-350 m. Scotia will undertake a trawl haul within five miles of each station position where possible or, failing that, choose an alternative.

The minimum spacing between trawl locations is set at 7nm. A further 22 secondary stations across the various strata have been generated to provide a source of additional stations and/or alternatives should any primary station prove unfishable.

Where time allows additional hauls will be conducted outside the existing strata (R1-R4) in depths between 350-500 m. This is a periodic check that is undertaken to test the current depth boundary at 350 m (see Figure 1).

One haul of 30 minutes duration will be made at each sampling station. Daily start times will vary depending on available daylight. The SCANMAR system will be used to monitor the headline height, wing spread and door spread for each haul. Bottom contact data from each trawl will also be collected using the NOAA bottom contact sensor which will be mounted on a bar in the centre of the ground-gear.

In addition to the routine sampling, biological data will be collected for target species in line with the EU data regulation.

All fish will be processed in accordance with the protocols as described in the Manual of the IBTS (International Bottom Trawl Survey) North Eastern Atlantic Surveys. Series of ICES (International Council for the Exploration of the Seas) Survey Protocols SISP 15. 92 pp. http://doi.org/10.17895/ices.pub.3519.

During trawl downtime at night, Scotia will take sediment samples using a Van Veen Grab. The sampling positions for the grabs will be confirmed on a day to day basis and will be influenced by vessel location at the end of each trawling period.

Regular planning meetings with the fishing master and captain will take place during the survey and will be scheduled at a time that is mutually convenient to all those concerned.

Figure 1: Survey map showing stations generated for 1319S. Red stratum (R1) = 0-150 m depth, green stratum (R2) = 150-200 m, blue stratum (R3) = 200-250 m and light-blue stratum (R4) = 250-350 m. Boxes/polygons represent restricted or closed areas. Closed circles = primary haul positions, open circles = secondary haul positions. Potential station positions >350 m depth are denoted as black open circles.

Further Information:

 

The post Rockall Haddock Survey appeared first on Marine Scotland.

Half-way there! Monitoring the West Shetland Shelf

Marine Scotland Blog - Mon, 2019-09-09 09:00
MRV Scotia

Survey: 1219S

(Times given are in Coordinated Universal Time (abbreviated to UTC), 24-hour format throughout.)

With a full complement of staff aboard, including 19 officers and crew and a team of 11 scientists from Marine Scotland Science (MSS), the Joint Nature Conservation Committee (JNCC) and the National Museum of Scotland, MRV Scotia departed Aberdeen on the morning of 26th August and made way for the West Shetland Shelf (WSS) Nature Conservation Marine Protected Area (MPA) (Fig. 1). The 1219S WSS offshore monitoring survey had begun with high expectations after the discovery made during the last visit.

Figure 1: The West Shetland Shelf (WSS) Nature Conservation Marine Protected Area (MPA), areas (boxes A – G) identified for sampling and location of the wet-test site.

 

Upon leaving port, a vessel familiarisation tour was conducted for those scientific staff who were new to the boat, or who hadn’t sailed in the preceding six months. An abandon ship drill was also carried out.  A ‘wet-test’ of sampling equipment was carried out between 12:30 and 15:30 on the 26th August, 25 km north of Fraserburgh (Fig. 1). This included a test of:

  1. The drop frame camera system that is being used to capture video footage and still photographs of the seabed and the marine life it supports and is fitted with an ultra-short baseline transponder (USBL) to record its location underwater with high accuracy (Fig. 2).
  2. JNCC’s new DEFRA funded Hamon grab (on its maiden voyage), which is being used to take sediment samples for characterisation of the epi- and infaunal communities and sediment type (Fig. 3).


Figure 2: Drop-camera system used on survey (left); drop-camera operations on board (top middle); digital still image of seabed (bottom middle); example output from the processed USBL data showing the position of the drop-frame and ship (top right); drop camera retrieval (bottom right).

 

 

Figure 3. JNCC’s new Hamon grab (above); grab sample processed (top right); sample processing station manned by JNCC scientists (bottom right)

Once testing was completed, transiting resumed and we arrived at survey box B in the WSS MPA (Fig 1) at 03:00 hours on the 27th August. A sound velocity profile (SVP) cast was taken (SVPs are used to calibrate the multibeam echosounder (MBES) system on board) and an MBES survey of box B began and continued until first light on the 27th. Boxes B and D are the primary targets for MBES sampling due to the coarser sediment in these areas, you can read JNCC’s blog post about MBES on 1219S here. At first light (06:00) – to allow sight of any creel marker buoys that present a snagging risk to towed gear – the drop-camera survey of stations within box B commenced and continued until 10:00 after which the MBES survey of box B resumed and continued until midnight on the 27th August.

We then transited to survey box A and undertook drop-camera sampling until 10:30 on the 28th, at which point Hamon grab sampling began and continued until midnight. Many thanks are due to MRV Scotia’s engineering crew for their work in adapting the Hamon grab; a retaining bar was installed to keep the lifting wire on the pulley as this had been slipping out while retrieving the grab. Sampling of box A was completed on the 29th August (drop-camera: 00:00 – 09:30, Hamon grab: 09:30 – 12:45).

We then set our sights on box F, arriving at 14:00 and grab sampled until 17:30 when high winds and rough seas prevented equipment from being deployed and retrieved safely. This period of downtime lasted approximately 15 hours, with grab sampling in box F resuming at 09:00 on the 30th August until midnight when grab sampling of this area was completed.

Drop-camera sampling of box F began and continued until completed at 09:00 on 31st August. Transit back to box B was made and the MBES survey here resumed at 12:30 until completed at 23:15. Note the different shape of box B presented here to that given in the survey programme: it was necessary to adapt the shape due to the presence of creels in the south of the survey box.

Drop-camera sampling of box B continued from 23:15 (31st August) to 03:30 on the 1st September when the weather worsened making the drop-camera unworkable. Transit to box D was made and MBES surveying commenced at 06:45, continuing to 10:00, when sea state affected the quality of the acoustic data to an unacceptable extent and all scientific operations ceased. The MBES survey of box D resumed at 14:00 and lasted until 21:30 on the 31st, when sea state had improved sufficiently. With conditions continuing to improve, transit back to box B to complete drop-camera and grab sampling was made, with all sampling in box B completed by 14:00 on the 2nd September.

Good progress is being made with three boxes fully completed and two others started. Despite the weather forecast, the team is optimistic the survey objectives will be achieved.

The catering staff are keeping spirits high with excellent fayre, while both the officers and deck team are making sure we are on-target, safe and entertained.

Further Information:

The post Half-way there! Monitoring the West Shetland Shelf appeared first on Marine Scotland.

Juvenile Fish Habitat

Marine Scotland Blog - Tue, 2019-09-03 13:00

MRV Alba na Mara

Survey: 1519A Programme

Duration: 2-21 September 2019

Gear:

  • 2 x Jackson Rockhopper Trawl BT158 with 10 mm Cod end + Spare
  • Scanmar net sensors – trawl width, height, and depth (x2 units)
  • 2 fleets of fish traps
  • Fish/prawn sorting table
  • SBRUV – baited camera frames – (QTY 2)
  • 2 x Day grab, grab table

Background and Objectives:
1519A will conduct a benthic survey of juvenile gadoids within the Firth of Clyde. The primary objective of 1519A is to identify whether the availability, quality and distribution of habitat acts as a constraint on the number of juvenile fish that can grow and be recruited into the adult population. This study focusses on three gadoid species with differing habitat preferences; Atlantic cod, whiting and haddock, all of which the year-class strength appears to be established around the period of settlement to the demersal habit. The study will utilise three sampling methods: demersal tows, fish traps, and baited-camera census techniques. Data from these surveys will inform the development of species distribution models at a regional and stock scale and will also be used to compare the selectivity of the three sampling methods. Otolith based survivorship analyses will also be carried out post-survey to examine selection on settlement time and size-specific mortality. Genetic tissue will be stored and used post-survey to examine stock structure, primarily in cod. Habitat will be characterised using a combination of hydro-acoustic recordings (RoxAnn) for seabed classification and sediment grab samples.

Specific survey objectives are as follows:

  1. To collect data on juvenile gadoid abundance using three different sampling methods.
  2. To record substrate features at the point of sampling.
  3. To collect sufficient otolith samples suitable for survival analysis studies.
  4. To collect sufficient genetic material to investigate issues relating to stock structure.

Embarkation:
Scientists will join the vessel on the morning of 2 September. Weather permitting, Alba na Mara will depart on the same day, heading for the first survey site. IMPORTANT NOTE: It is essential that the wet lab freezer is completely empty before embarkation.

Survey Work:
The survey will be split into four distinct activities – demersal trawling, fish trap work, baited camera work, and a survey of the substrate – which will be performed at each station.

1. Demersal Fishing Survey
The demersal survey (30 minute tows) will assess the abundance, length-frequency-distribution, and weight-at-length of juvenile gadoids at 14 fixed stations within the Firth of Clyde (Figure 1- Trawl_Trap_Cam). Otoliths of five individuals per 1 cm size class will be retained for analysis at a later date. Occurrences of invertebrates and other fish species will be recorded and measured.

Scanmar units will be fitted to the wings and head line of the BT158 trawl to ensure the net is fishing correctly.

2. Fish Trap Survey
A fish trap survey at all demersal survey sites (Figure 1- Trawl_Trap_Cam) and within the NC MPA (Figure 1- Trap_Cam) within the Firth of Clyde will be carried out during 1519A. Traps (up to two fleets of four traps) will be deployed in the first half of the day and collected in the afternoon after a soak time of approximately six hours. Species composition and length frequency distributions of fish caught will be determined. All samples will be weighed and, where appropriate (cod, whiting, haddock), frozen. Occurrences of invertebrates and other fish species will be recorded and measured.

3. SBRUV baited cameras
In addition to demersal and fish trap survey sites (Figure 1- Trawl_Trap_Cam and Trap_Cam), stereo Baited Remote Underwater Video Camera (SBRUV) frames will be deployed in the No Take Zone (Figure 1 Cam) during daylight hours (2-3 units will be available). These will be left in the water for approximately 1.5 hrs before being retrieved. The deployment of baited cameras will happen at the same time as that of the fish traps and at distances sufficient to avoid any interaction with either the fleet ground gear or the other baited system (recommended minimum is 500 m). Footage will be downloaded to external media at the end of each working day. Species type, relative species densities (MaxN) and substrate type (assessed visually) will be classified post-survey.

4. Substrate Classification
To further aid the classification of the substrate at each sampling site, 1519A will also acquire RoxAnn records of the surveyed area and a Day grab will be deployed. Sediment samples will be collected from each grab and stored in the freezer. These will be analysed on return to the laboratory to determine particle size distribution in the sediment at each sample location.

Operations:
Survey operations will take place between the hours of 07:00 and 19:00 (all times BST). Stations will be surveyed depending on the prevailing weather conditions i.e. if wind strengths or wave heights are adverse, a precautionary approach will be adopted and those with adequate shelter from the weather will be selected. Alternatively, in poorer weather the trawl survey may be prioritised over other activities.

A half landing will be provisionally booked for a suitable port on 11 September to comply with working hours and to allow planned changes to the scientific crew.

Alba Na Mara will leave the study area in the morning of 20 September to allow sufficient time for the vessel to transit to Oban. Unloading will occur in Oban on Saturday 21 September. Scientists will disembark at this time.

Figure 1. 1519A: 2019 survey sites within the Firth of Clyde

 

 

 

 

 

 

 

 

 

 

 

 

 

Further Information:

The post Juvenile Fish Habitat appeared first on Marine Scotland.

Celebrating Merchant Navy Day

Marine Scotland Blog - Tue, 2019-09-03 09:00

Today is Merchant Navy Day.

For those of you who may not be aware, since 2000 Merchant Navy Day has honoured the brave men and women who kept our ‘island nation’ afloat during both World Wars, and celebrated our dependence on modern day merchant seafarers who are responsible for 95% of the UK’s imports, including half the food we eat, plenty of the fuel we burn and many other products and goods.

This year we wanted to bring you a blog from one of our marine colleagues, First Officer Safety Alexis Lee. In May this year, Alexis took over as Officer in Charge for a three-week trip on one of our Marine Protection Vessels, the MPV Minna.

It’s fair to say it was an interesting three weeks….

___________________________________

I found out  early in spring that in May, I was going to be asked to step up to be Officer in Charge of the MPV Minna in May – effectively, being put on temporary promotion for three weeks and acting as Commanding Officer, or Captain, for the three- week trip.

Having worked continuously towards this goal for the past 10 years of my life, taking countless exams and spending many, many months at sea I jumped at the opportunity. MPV Minna’s Commanding Officer, Captain Andrew Sutton would be travelling to Africa to volunteer on board African Mercy, a hospital ship operating all around the continent of Africa. And that would leave me in charge of the MPV Minna.

So what does it actually mean when you are Captain? Well it means I am ultimately in charge of every operation that takes place on board the vessel. From galley to engine room to navigating on the bridge- ‘the buck stops with me.’ As captain you are available 24 hours a day on board and must be ready to deal with any eventuality. Something I would quickly appreciate within 12 hours of sailing from Glasgow.

At 0400 on my first morning at sea, I received a call from the first officer executive to inform me that Belfast Coastguard had just called the vessel via VHF radio to ask for assistance. A fishing vessel and a tanker had just collided approximately 8 miles from our position and we were the closest vessel to the incident. Extra engines were put on line and emergency preparations were commenced. We began making our way at best speed. Thankfully arriving on scene we could see the fishing vessel was still afloat with no reported injuries on board- but with some significant damage. The damage suffered by the tanker was minimal. We were thanked by the coastguard and stood down after carrying out a damage assessment of the tanker. The fishing vessel was escorted back to port by the RNLI. It was certainly not a morning I will ever forget. And we made the BBC website!

The remainder of the trip was still to present quite a few challenges. However the support I received from the officers and crew on board was unquestionable. In addition to that I am very lucky to have some great colleagues from around the fleet and ashore, including other commanding officers, who gave me some fantastic advice.
As I type this, I am now back on the MPV Minna and back to my substantive rank. My Commanding Officer is safely back from Africa and life on board has returned to normal.  I’ve had chance to look back at that first trip and reflect on my experience.

A lot has been written in the media recently on the subject of imposter syndrome- I can certainly empathise with a lot of it. Despite knowing that I was ready to take this opportunity – quite literally having it written in black and white on my master mariner’s licence, there was still that nagging fear that maybe I wasn’t good enough or ready enough to take this on. It think it is very important to acknowledge these fears, but ultimately at sea you have stamp on them and get on with the job.

As well as that I was the first female officer in charge in the history of Marine Scotland Compliance. That was very much at the forefront of my mind throughout the trip and it comes with its own pressure. Rightly or wrongly, I felt an added responsibly to do the best possible job I could. And now 6 weeks later I am very happy to say that I feel I did that. And if I am lucky enough to be asked to do it again I would not hesitate.

Alexis Lee

Further Information

 

 

The post Celebrating Merchant Navy Day appeared first on Marine Scotland.

Prey Species across Smith Bank

Marine Scotland Blog - Fri, 2019-08-30 14:49
MRV Alba na Mara

Survey: 1419A Programme

Duration: 27-30 August 2019

Locations:
  • Beatrice Offshore Windfarm Limited (BOWL);
  • Moray East Offshore Windfarm (MEOW);
  • Moray West Offshore Windfarm (MWOW).
Objectives Primary Objectives:
  1. Study the distribution of prey species (fish schools and zooplankton patches) across Smith Bank in relation to data available from BOWL post-construction digital aerial surveys and University of Aberdeen (UoA) Passive Acoustic Monitoring (PAM) surveys of top predators.
  2. Compare the distribution of schooling sandeels in summer with data on their presence in the sediment from the BOWL/MEOW winter sandeel monitoring.
  3. Recover two Acoustic Doppler Current Profiler (ADCP) devices deployed in the BOWL area.
Secondary Objective:

Collect hydrographic data to further validate the Scottish Shelf Model (SSM) and incorporate its outputs into assessment of drivers of predator distribution.

Procedure

Alba na Mara will conduct an acoustic survey at an average speed of 8 knots along key transects between wind farm turbine rows (see Figure 2), to capture data on mid-water feeding sandeels using all available frequencies from the EK60 echo sounder.  Concurrent seabird and cetacean visual surveys will collect predator data during the transects.

Pelagic sampling for sandeels using the PT154 will normally be conducted early on in the day. Sandeel dredge tows or Day grabs will be deployed as a back-up if required.  Fishing haul positions will be chosen along the survey transects but not necessarily in the same orientation.

Plankton sampling will be conducted using the dual “bongo” net, fitted with mesh sizes of 200 and 68 µm. Collected samples will be preserved in each of: 70% alcohol, 4% formaldehyde and frozen in vital stain neutral red.

Sampling positions have been selected to cover the southern part of the BOWL area based on the survey transect lines. Three of the selected positions will be prioritised and the two remaining ones will be done if time allows. Figure 3 shows all plankton sampling positions.

The two ADCP devices will be retrieved during the survey when possible, Figure 4 shows the locations of these devices.

This survey continues the work undertaken during Alba na Mara survey 0919A.

Survey Activities During Turbine Piling Activities

The Alba na Mara will survey around any turbine piling activities should these start at the MEOW site. Alba na Mara will collect biological samples at a predetermined safe distance from piling activities. Daily contact with the MEOW operation team will ensure that the Alba can sample soon after piling events begin.

Conductivity Temperature Depth (CTD) and water sampling (seabed and mid-water) will be simultaneously undertaken at each plankton station, with data collected for the Scottish Shelf Model. See Figure 3 for locations.

Figure 2: Proposed transects for fisheries acoustic surveys (grey dots represent wind turbine locations, both built and planned).

Figure 3: Hydrographic and plankton sampling positions (grey dots represent wind turbine locations, both built and planned, cyan dots represent sampling locations from 0919A).

1419A Figure 4 ADCP locations. These will be collected during 1419A

 

Further Information:

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Upper Loch Creran MPA

Marine Scotland Photos - Fri, 2019-08-30 13:38

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Upper Loch Creran MPA

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Seal haul out Loch Creran

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Seal haul out Loch Creran

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Ex fishing boat ashore on Loch Creran

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Ex fishing boat ashore on Loch Creran

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On patrol in south west Scotland

Marine Scotland Photos - Fri, 2019-08-30 09:04

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On patrol in south west Scotland

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On patrol in south west Scotland

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On patrol in south west Scotland

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On patrol in south west Scotland

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On patrol in south west Scotland

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On patrol in south west Scotland

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On patrol in south west Scotland

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On patrol in south west Scotland

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On patrol in south west Scotland

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On patrol in south west Scotland

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On patrol in south west Scotland

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On patrol in south west Scotland

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On patrol in south west Scotland

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We’ll be back! Our Return to the West Shetland Shelf

Marine Scotland Blog - Fri, 2019-08-30 08:00

MRV Scotia

Survey: 1219S Programme

Duration: 26 August – 11 September 2019

Introduction

The survey plan outlines the monitoring survey requirements for West Shetland Shelf (WSS) Nature Conservation Marine Protected Areas (MPAs). WSS has been identified for monitoring survey effort following discussion between Joint Nature Conservation Committee (JNCC) and Marine Scotland Science (MSS), taking into account the 2019/20 JNCC MPA monitoring survey prioritisation process, (McBreen & O’Connor, 2018), the Scottish MPA Monitoring Strategy (Scottish Government, 2017) prioritisation principles and logistical considerations.

In addition to WSS, Pobie Bank Reef (PBR) Special Area of Conservation (SACs) is also considered as a contingency site but will only be visited in the case that it is not possible to survey WSS.

MPAs and Special Areas of Conservation (SAC) are designed to meet conservation objectives under the Marine (Scotland) Act (2010) and EC Habitats Directive (1992) respectively. These sites will contribute to an ecologically coherent network of MPAs across the north-east Atlantic, as agreed under the Convention for the Protection of the Marine Environment of the north-east Atlantic, or Oslo-Paris Convention (OSPAR) and other international commitments to which the UK is signatory.

Main Objectives West Shetland Shelf:

Seven survey boxes have been positioned inside and adjacent to WSS MPA (Figure 1). For each box the priority is to:

  1. Acquire full coverage multibeam.
  2. Collect drop-camera video and stills from 25 stations (station position will be determined based on processed multibeam).
  3. Collect and process a single Hamon grab sample from a subset of the 25 stations (only stations deemed suitable for grab sampling will be revisited with the Hamon grab).
  4. Increase replication at drop-camera transects (four additional camera transects) and grab samples (two additional grabs) at a subset of one drop camera stations and three grab stations.
Pobie Bank Reef (Contingency Survey Site):
  1. Acquire multibeam.
  2. Collect drop-camera video and stills from selected stations.
  3. Collect and process a single Hamon grab sample from selected stations.
Secondary Objectives:
  1. Collect additional drop-camera video and stills and/or Hamon grab samples to ground-truth the multibeam data.
  2. Collect Hamon grab samples for the purpose of DNA analysis.
  3. Collect Van Veen grab samples at a subset of Hamon grab stations for the purposes of a gear comparison study.
General

The survey will be undertaken from the MRV Scotia with 16 days at sea. Two 12-hour shifts will be used to cover each 24 hour period. The night shift (00:00-12:00) will primarily be used for drop-camera sampling and the day shift (12:00-00:00) will primarily be used for grab sampling and multibeam acquisition. However, both shifts will be capable of using the multibeam and grabbing gear if necessary.

Due to the large area and depth range of WSS (4,083 km2 and 70-150 m, respectively) the site will be monitored using a nested box approach, to make the best use of the survey time available, and to increase the power to detect change within each survey box. The seven boxes are labeled A-G (A being the highest priority and G lowest priority) and have been positioned inside and outside WSS, each box has dimensions of 5 x 10 km (see figure 1).

Following main survey objectives for WSS, each box will initially be sampled to acquire 100% multibeam (bathymetry and backscatter). Bathymetry and backscatter data will be processed while at sea and the outputs used to target sampling stations.

Sampling Stations

All sampling stations will be visited to acquire 150 m (~15 minute) drop-camera tows. At a subset of one station per survey box drop-camera tow replication will be increased.

At these increased replication stations, the vessel will move 10 m perpendicular to the direction of the first transect, and complete a shorter 50 m (five minute) tow and repeat this process until there are five approximately parallel transects (i.e. as parallel as is possible bearing in mind logistical constraints in terms of maintaining desired direction of travel along the five parallel transects due to potential changes in conditions (e.g. tidal direction and prevailing weather)).

These increased replication drop-frame camera stations will consist of five transects of 50 m length (the video from the single 150 m transect will be truncated post survey) placed within a 50 m radius bullring surrounding the station.

Video collected at each station will be assessed for suitability for grab sampling. A subset of stations which are deemed suitable will be revisited to collect a single Hamon grab sample. A further subset of three stations per survey box will be increased replication stations. At these stations a total of three replicate Hamon grab samples will be collected. Hamon grab samples must have a volume of 5 L or more to be considered valid for monitoring. Up to three attempts will be made to acquire a valid sample for each grab replicate.

A sub sample for particle size analysis will be taken from each grab sample, and the remaining sample will be processed using 1 mm sieves and fixed in formalin solution.

Pobie Bank Reef SAC is a contingency site. If this site is surveyed a similar sequence of multibeam acquisition, drop-camera transects, and Hamon grab samples will be followed.

At both sites additional grab and camera stations may be planned to address the secondary objectives.

Further Information:

The post We’ll be back! Our Return to the West Shetland Shelf appeared first on Marine Scotland.

Measuring crab and lobster

Marine Scotland Photos - Wed, 2019-08-28 12:42

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Measuring crab and lobster

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Measuring crab and lobster

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Measuring crab and lobster

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Measuring crab and lobster

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Measuring crab and lobster

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Scotia’s Hunt for Organic Carbon

Marine Scotland Blog - Wed, 2019-08-21 14:22

I am a second-year PhD student at the University of St Andrews and was recently very fortunate to be one of the research scientists aboard the Scotia 1019S survey that took us across Scotland’s seas at the end of July. Following an unpredictable summer, we weren’t sure of what to expect weather-wise at sea. However, we needn’t have worried, we were treated to clear blue skies and calm seas for most of the 10 days!

The researchers on board all had the common goal of improving our understanding of how organic carbon is cycled and stored within the marine environment and this was done via sampling the seabed and water column.

My PhD research is focussed on understanding the spatial distribution of organic carbon within seabed sediments on the Scottish Continental Shelf. It is understood that the seabed is a long-term store of organic carbon (that originated from the atmosphere as carbon dioxide), however there are gaps in our knowledge of more specifically where this carbon is found. Understanding the oceans’ role in storing carbon is important when considering this environment in terms of climate mitigation strategies.

I had two main aims for this data collection opportunity aboard Scotia. The first was to sample the seabed over as large a spatial range as possible. My project aims to generate a spatial inventory of organic carbon on Scotland’s Continental Shelf to build a picture of where carbon hotspots might exist.

As I am interested in the surface seabed, I used a Day Grab, which is lowered to the seafloor and triggered, to collect a large ‘scoop’ of sediment. Over the course of the cruise, I was able to collect over 130 grab samples from different locations on the shelf which I will analyse in the lab. This dataset will form a key part of my research to map the spatial distribution of organic carbon on the shelf.

The second objective was to test a novel mapping method using multibeam backscatter data (acoustic data) to predict where organic carbon is stored. The seabed is a challenging environment to sample because we can’t ‘see’ it unless we employ some form of technology. Multibeam echosounders are used to map seabed substrates because of the relationships between how sediments reflect sound. If we can use sound to identify muddy sediments, we might be able to predict that these areas will also be enriched in organic carbon. To test this theory, I ground-truthed a multibeam dataset from the Moray Firth on the east coast of Scotland by collecting multiple surface grabs. I also collected larger, and deeper seabed samples using a box core in different sediment types to understand relationships between sediment type and organic carbon with depth. In the lab, I will analyse this sediment to characterise its physical properties and organic carbon content. This information will be used to understand the links between sediment type, acoustic backscatter data and organic carbon.

Mapping carbon hotspots in seabed sediments is the first stage in building a marine carbon inventory and acknowledging seabed sediments in their role as long-term carbon stores and natural capital assets.

By Corallie Hunt

Further Information:

The post Scotia’s Hunt for Organic Carbon appeared first on Marine Scotland.

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