Map of the fifth cruise of Nectalis
Last night was our last sampling station with 2 deep trawls at 450 and 275 m depth, 3 CTD casts, one TAPS cast and one zooplankton net. We finished working at 1am and everybody was tired and happy to finish the work. Today was about writing reports, saving all the data, cleaning and packing all the equipment to get ready for tomorrow when we will bring all the equipment in the lab.
The cooks did an extra great job for our last lunch with an excellent buffet and a magnificent cake to celebrate the end of those 2 weeks of intense work.
The micronekton team at 1am after the last trawl of the cruise
The last lunch onboard with an extravagant cake prepared by the cooks
We are due in port tomorrow evening and we still have a long way to go so we are doing less sampling stations. After the sampling station that finished around midnight last night, we steamed all night and all of today. This morning we are crossing the Antigonia seamount and the acoustic echosounder shows us a layer of organisms around 350 m depth that bumps into the seamount slope. The summit of the seamount is at 60 m depth and almost flat; we observe nice acoustic detections just above the bottom.
On the slope of the Antigonia seamount
Acoustic detection just above the bottom on the flat summit on the Antigonia seamount
We started the sampling station around midnight with 2 shallow trawls (20 and 60 m depth) because of the bad weather. Catch were small but with interesting specimens. Particularly we found 4 specimens of Alatina which are potentially deadly box jellyfish. We are very careful to wear gloves when we collect the specimens from the codend in case of the presence of jellyfish and we always have some vinegar within easy reach to neutralise the toxin in case of sting. So far we never had any problem but we stay attentive.
Only a couple of days left and we had to revise our cruise track once more. In the end we had to remove 2 sampling stations from our ambitious plan. On our way back we will survey the Antigonia seamount and La Torche bank to acquire physical and acoustic data. Those two features nearly reach the surface (less than 50 m depth) and are locations favoured by Humpback whales; however we do not know why.
Four Alatina, potentially deadly box jellyfish
Last changes to the sampling cruise track
Sleeper lobster larvae
Diphyidae, a gelatinous organism
A fish of the family Opisthoproctidae which has eye directed at the top
A shrimp of the family Caridae
Last night towards the end of the second trawl all the alarms started rigging. We had a major failure on the hydraulic system with oil spill onboard. The trawl being in the water we had no choice but to quickly bring back in all the cable and the large heavy doors that kept the micronekton net open. Once the doors where in the chief mechanic asked to stop everything so that they can remove the oil and try and see what was wrong. The net was still in the water and it stayed there for 40 minutes before we decided to use the small hydraulic pump to bring the net onboard. After that we stopped all the operations so that the mechanics can have a good look at the problem. It was past midnight and we decided to wait for daylight for the mechanics to try and resolve the problem; in the meantime we steamed towards the following station.
This morning the mechanics were at work early and they figured out some seals had broken and luckily they had spare seals. All the reparations were done in a few hours and we could start working at sampling station 15. We started with only one trawl at 380 m but as for all our tows during the day, the catch was very poor. Most of the specimens collected were gelatinous organisms with a few squids and fish. We also collected the juice from the tray to conduct some experimental analyse and try to determine the list of species from DNA fragments found in the liquid.
Today is Sunday, croissants for breakfast and couscous for lunch!
Content of the trawl with mainly gelatinous organisms
Collecting the juice from the tray for DNA analysis
Satellite images are showing that we are in an area where chlorophyll, that is phytoplankton, is very concentrated. Since yesterday we indeed started to notice large patches of Trichodesmium floating at the surface. We took this opportunity to take a few shots from above.
In one of our trawls today we caught a large mass of Pyrosome which is a gelatinous organism forming a colony made of thousands and millions of individuals; the colony can reach several meters long.
Satellite image showing in red the strong concentration of chlorophyll
Trichodesmium at the surface
Preparing the kite to take pictures from above
We arrived last night close to Hunter Island which was not visible to us though. We had two very successful trawls at 80 and 225m depth. So far they are the largest catch we got. Our first trawl caught mainly small size lanternfish Myctophidae: Ceratoscopelus warmingii. In the second trawl we had a good diversity of specimens with what we think is a small swordfish and some beautiful dragonfishes. The work continued late in the night especially as we got some trouble with the electronic cable used to tow the CTD and the zooplankton net.
The last woman standing went to bed this morning at 6am while the first ones were getting up one hour later to enjoy the show provided by Hunter Island. We steamed around the island with some fishing lines and got a few wahoos. Hunter reaches 250 m above the sea and is of volcanic origin with only small sulphur smoke visible. If it was less dramatic than Matthew, it was still a very spectacular view. The island has more vegetation than Matthew with some bushes where many birds seeming resting or nesting.
The small size lanternfish Myctophidae: Ceratoscopelus warmingii
Diversity of the catch at 225 m depth at night with probably a small swordfish in the middle
Beautiful dragonfish head with a large purple photophore below the eye and a chin barbell
View of Hunter Island
View of Hunter Island
Birds flying over the top of the island where we can see some bushes
We arrived this morning at Matthew Island which welcomed us with some swell, 20 knots wind, a strong sulphur smell and fumes. It was spectacular! Matthew is an active volcano reaching 200 m above the sea level but only forms a very small island. We can see fumes coming out of the crater area and yellow patches of sulphur on the cliff. The water surrounding the volcano had greenish and brown colour. We put a few lures in the water and the catch was not bad with 2 yellowfin, 3 wahoo and 2 rainbow runners.
We looked at the stomach content of the caught fish and we had the bad surprise to find some plastic coming from food packaging in the stomach of one of the yellowfins. The plastic discards reach even the most isolated areas.
The 2 trawls of the day were very poor but we brought back a small Regalec and a beautiful pinkish flat fish. Once adult, Regalec is the largest bony fish known and can reach 7 m long.
Plastic packaging in a tuna stomach
Looking the tuna and wahoo stomach contents
On the right a small Regalec and on the bottom left a flat fish
Last night while we were working on the micronekton, a black and white bird with a long thin beak fell down on the deck, probably attracted by the lights. It took us some time to catch it as it was walking around and below the winch getting some grease on its body. It defended itself with its beak bitting us but in a few minutes we were able to release it at the back of the deck where it joined other birds flying around the boat.
Today’s sampling station was during the day and the content of the trawls was very small but with interesting specimens.
We are late on our sampling plan and we had to revise our strategy by removing 2 sampling stations and modifying the track in order to arrive on the 7th of December in Noumea. The sampling plan will probably change again according to the progress of the work. We are still sampling the anticyclonic eddy and we should arrive tomorrow morning at Matthew Island (station 9). We still have 3 sampling stations in the anticyclonic eddy before crossing the front between eddies and entering the cyclonic eddy.
It has been a long day with 2 sampling stations, we started a 4am and we finished at 3am the following day. The first trawl of the night conducted at 230m depth was particularly interesting with a lot of shrimps and large fish; the success is attributed to the special dance conducted by the lieutenant to bring luck.
We left the northernmost point of our sampling strategy and we keep working in the anticyclonic eddy we entered 2 days ago. We observed a clear difference in richness between our first sampling stations and the eddy with is much poorer.
Analysis has started on the acoustic data.
Two days of acoustic signal between the surface and 700 m depth. The blue slider at the bottom of the graph indicates dusk, the brown slider indicates night and the pink slider indicates dawn. We can see on this graph the vertical distribution of the micronecton according to depth. Micronecton is very dense at the surface at night (green marks) and stay important during the day. At depth between 500 and 600 m there is also an important micronecton layer day and night. At dusk and at dawn we can see micronecton migrating quickly from depth to the surface and from the surface to depth respectively.
We made the most of the transit time between the 2 sampling stations to do a few pictures from above using a kite.
Last night was very busy with the work at station 4 finishing at 2am. Everybody went to bed for a well-deserved rest, except the staff on watch, until the next sampling station that was planned at 11am Sunday morning. The cooks, Jacques and Gaby, had prepared for us a delicious breakfast that helped us working. We all gained in efficiency and everyone is now well familiar with the tasks; the sampling station of the day lasted 6 hours which is our minimum so far.
We are making the most of the calm weather to conduct some delicate tasks, particularly taking pictures of organisms collected. As we are practising more, we should soon be able to take excellent shots. Part of the organisms photographed are sampled (a fin for the fish or a leg for the crustaceans) to establish a characteristic part of their genetic code, this is barcoding. Those genetic sequences are then recorded in the international databases available to all. Hence we are contributing to complete the inventory and the knowledge of the species.
Taking pictures of specimens and the vials to collect samples for barcoding
The hatchetfish Argyropelecus aculeatu
A small crustacean Thysanopoda cristata
The small crustacean Phronima sp. and its home, the remains of a salp (gelatinous organism).
Recovering water samples
Micronekton net setting
Last night we conducted the third sampling station and while the CTD was coming up we observed a lot of particles floating at the surface of the sea. We throw a bucket to collect some samples which we suspect are Trichodesmium. The particles were very dense and we will look at them under the microscope once we are back in the lab. We collected zooplankton and our first trawl was very disappointing with a few fish. However our second trawl conducted at 450 m depth brought back some interesting specimens:
- Isistius brasilensis a small cookie-cutter shark that feeds by removing pieces of large animals with its powerful jaws ; the animals attacked will survive generally and will show circular scars on their skin
- Bright red shrimps typical of deep waters
- Fish with impressive jaws
We finished working around 4:00 am and we started steaming for about 15 hours.
During the day we observed strange cloud-shape structures on the echosounder between 300 and 400 m depth, we don’t know what it could be.
Particles collected at the surface, we suppose they are Trichodesmium
Sorting the specimens of the deep trawl (~450 m)
Coockie-cutter shark Isistius brasilensis
Bright red deep shrimps
Deep sea fishes of the families Gonostomatidae (bristlemouth) and Stomiidae (dragonfish)
Deep sea fishes of the families Myctophidae (lanternfish) and Sternoptychidae (hatchetfish)
Acoustic signal showing organisms located between 300 and 400 m depth during the day
The day started early for the acoustic and micronekton sampling team as they woke up at midnight to conduct the first night trawl of the cruise. We targeted the same depth as a few hours earlier during the day: 25 m, where the acoustic signal was the strongest demonstrating that micronekton located deeper than 500 m during the day had come up to the surface during the night. After 30 minutes of trawling an alarm rings and the hydraulic system for the winches does not work, it is not possible to haul the net back onboard. The mechanic team is woken up to try and repair as soon as possible. After a number of checking and hard work, the breakdown is repaired after 2 hours. The net is hauled back and contains a lot of gelatinous organisms, many small squids, fish and crustaceans. A few other incidents will occur during the sampling station which will last 8H30.
We now steam towards the East to reach the island of Walpole that we can see not that far away. This small island is completely flat surrounded by high cliffs. It is covered with bushes and we can see numerous seabirds around: boobies, frigate birds, terns… We put a few fishing lines at the back of the vessel but it is not the right time of the day and only a rainbow runner will taste our lure.
Installing the depth probe on the net
Setting the micronekton net
Walpole island cliffs
Walpole island cliffs
Walpole island cliffs
Walpole island cliffs
A frigate bird
Catch of the day: rainbow runner
Cruising against the wind and the swell did not help for a good night sleep and some of.us were seasick this morning. We arrived at the sampling station this morning at 7:30 and we started working with two casts of the CTD. The CTD allows us to establish a profile between 600 m depth and the surface of the salinity, the temperature and the fluorescence which is an indicator of the phytoplankton richness. On this profile we observed a maximum of fluorescence at 85 m depth which is not very deep. By filtering the water we observed numerous filaments of Trichodesmium (bacteria that can photosynthesize); it is indeed the beginning of their high season.
We also sent the zooplankton net at 600 m depth but we had the misfortune to realise that it was not working. It appears that there were the net closing system was blocked.
While our electronician was repairing the net, we set the micronekton net at 25 m depth where we had observed some detection on the echosounder. The content of the net was poor with mainly some juvenile fish. Le zooplankton net was repaired and we managed to set it twice.
Our first sampling station lasted 9 hours which is very long, but now that the crew is familiarised with the equipment and all instruments are up and running, the following stations should be shorter.
Repairing the zooplankton net
Our new photographic system to take pictures of fish onboard
The catch of the day
We left Noumea this morning at 8:30am to steam for 3 hours towards ile Ouen where we anchored in a sheltered bay to conduct the calibration of our EK 60 fishing echosounder. The echosounder is an instrument that sends an acoustic beam in the water below the vessel. The acoustic waves bounce on the fish located in the beam and the signal comes back to the vessel. It allows us to estimate the quantity of fish and the depth of the organisms. This instrument is central in our cruise as one of our goals is to estimate the quantity of micronekton (2-20 cm long fish, crustaceans and squids consumed by tuna and seabirds) and to determine their spatial distribution. To calibrate the echosounder we place under the vessel in the acoustic beam a 4 cm diameter metallic (tungsten) ball which represents a perfect fish with known characteristics. By calibrating the echosounder we can adjust the parameters of the instrument to make sure our measurements are accurate.
For those not working on the acoustic calibration, we make the most of our time in those quiet waters to check all the instruments, install all the equipment in the lab and to assemble the zooplankton multinet.
Ready to embark
We are leaving Nouméa
Assembling the zooplankton net
Installing the water filtration system to collect phytoplankton
Installing the photographic system for the micronekton
Calibrating the echosounder
The kitchen team is working hard to maintain the moral of the group
The day started early with a radio interview at 7:30am this morning with Wallis & Futuna 1ère after a media information was released in New Caledonia and Wallis & Futuna for the Biopelagos project and the Nectalis 5 cruise. RRB a new Caledonian radio also came onboard for interviews while we were loading the equipment. This mobilisation day gives us the time to check all the equipment and to find the right spot onboard to store it safely in case we encounter bad weather.
Interview with the New Caledonian radio RRB
Checking the rosette with the bottles to collect water and the CTD probe (salinity, temperature, depth)
Checking the zooplankton net
On the bridge in front of the map table
Research vessel Alis
The Biopelagos project banner
Nectalis 5, the return of the last cruise
In October 2015 Nectalis 4 was supposed to be the last cruise of the Nectalis series. However due to motor damages we had to come back earlier after only 4 sampling stations instead of the 19 sampling stations planned. The opportunity was given back to us to conduct this cruise again and it is happening now.
As for Nectalis 4 we are planning to explore the southern part of the New Caledonia EEZ and we would like to target eddies to try and understand their influence of the physical, chemical and biological components of the ecosystem.
Eddies are sections of moving water that swirl off from the main current and loop back on themselves, forming something like whirlpools. The topography of the ocean floor, such as seamounts or islands, by disrupting the flow of the current can help eddies to form in the lee of the obstacle. These eddies consist of water that is of different temperature than the water that surrounds them. They are usually around 100-200 km wide; they can last several weeks and will typically travel at the speed of 1m/s (3.6 km/h or 86 km in a day). We believe that, in certain conditions, eddies can bring nutrients at the surface and then create an environment favourable for higher development of phytoplankton, zooplankton and micronekton. This enhanced ecosystem could attract tuna and other large pelagic predators or seabirds. The scientific literature provides contradictory information about eddies impact on the ecosystem so we thought we should better go and check what is really happening there.
Draft cruise plan and sea level anomaly
Draft cruise plan and bathymetry
Draft cruise plan and chlorophyl
Draft cruise plan and sea surface temperature
As for the previous Nectalis cruise we will collect oceanographic physical and chemical data:
- sea surface temperature and salinity along the track of the cruise with TS probes,
- at each sampling station we will lower a CTD probe (Conductivity, temperature, depth) down to 600 m
- with the CTD probe we have 9 water bottles that will be closed at different depth. Nitrates, Silicates and Phosphates will be measured at each depth using the water samples.
For the biological parameters, at each sampling station,
- using the water samples the particulate organic matter (including phytoplankton) will be measured and collected for stable isotope analysis,
- several phytoplankton pigments will be measured such as Chlorophyll and Phycoerythrin,
- the number of bacteria and phytoplankton cells of different size will be counted,
- using a zooplankton net we will collect zooplankton at different depths between 200 m depth and the surface, to identify the organisms, estimate their quantities and measure isotope and mercury concentration,
- using an acoustic device called the TAPS that is lowered down to 200 m we will be able to estimate the amount of zooplankton in the water column,
- using a micronekton net we will collect small squids, crustaceans and fish (2-20 cm long) at depth between 550 m and the surface; we will identify them, count them and conduct some analyses on them (bar coding, stable isotope, mercury)
- finally, along the track of the cruise we will record the acoustic signal of the micronekton using a SIMRAD EK60 echosounder to estimate their quantities and their spatial distribution.
We will continue the experiment tested during Nectalis 4 about environmental DNA (eDNA). By collecting and filtering water samples, we will collect and analyse DNA fragments left behind by the living organisms that shade scales or mucus. By comparing our results to a DNA database we will identify organisms that were in the water without the need to collect the organism themselves. This technique is very promising but still in development so our goal is to try and prove that the method works.
The Nectalis 5 cruise will depart on the 23rd of November 2016 and our scientific team of SPC and IRD staff will be at sea for 2 weeks of hard work coming back on the 7th of December.
Nectalis 5 is now part of a broader project BIOPELAGOS that focuses on the biodiversity of oceanic pelagic ecosystems for a better conservation and management of outstanding natural areas of New Caledonia and Wallis and Futuna. This project is funded by the BEST2.0 programme of the European Union and the NECTALIS 5 cruise is also co-funded by SPC, IRD and the AAMP (Agence des Aires Marines Protégées).