Using Gas to Grow – One Ten East Log

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One Ten East Logs from the IIOE-2 voyage aboard RV Investigator will be posted on the WAMSI website during the month long voyage.

Log from One Ten East

The RV Investigator is currently undertaking oceanographic research along the 110°E meridian off Western Australia as part of the second International Indian Ocean Expedition. The voyage is led by Professor Lynnath Beckley of Murdoch University and the research is supported by a grant of sea time on RV Investigator from the CSIRO Marine National Facility.

Date: May 26, 2019 Time:  1200 AWST
Latitude: 26°S Longitude: 110°E
Wind direction: SSE Wind speed: 18 knots
Swell direction: SSW Depth: 3988 m
Air temperature: 22.6°C Sea temperature: 23.8°C

Notes: There is a clear influence of the Leeuwin Current on the samples being collected with more tropical species appearing in the plankton nets and the seabirds sighted.

Using Gas to Grow

By Dr Eric Raes

During this voyage we are focusing our research efforts on nitrogen in particular, as this element is essential for all life forms on Earth. On land, we are accustomed to adding nitrogen as a fertiliser to increase the growth and yield of our crops. As on land, in the sea, nitrogen is a vital nutrient for the growth of microscopic organisms. On this voyage, we are examining the different ways nitrogen is used by the microbes and phytoplankton, which supply us with the oxygen that we breathe.

One of our questions is to determine how much energy from the sun is captured by the phytoplankton and how the availability of nitrogen controls their growth. Another question targets a special group of microscopic life, the nitrogen gas fixers! These microorganisms are able to use the nitrogen gas from the atmosphere (which is roughly 80% nitrogen gas and 20% oxygen). Although most organisms use oxygen, only a select few can actually use nitrogen.

In agriculture, we have long known about the beneficial effects of microorganisms that use nitrogen gas such as Rhizobium in the root nodules of peas and beans. In the ocean, however, the beneficial effects of using nitrogen gas as an energy source for growth are less well understood. During our voyage we have set up experiments to measure just how much nitrogen gas the microorganisms are using. The results from these experiments will give us a better understanding how much food (in fact, energy for fishes), is available in the south-east Indian Ocean and what might happen in the future.

Dr Eric Raes (CSIRO) with Cora Horstmann (PhD student at the Alfred Wagener Institute in Germany) tending their experiments in the through-flow seawater incubators on board the RV Investigator. Photo: Micheline Jenner AM

 

Dr Eric Raes (CSIRO) with Cora Horstmann (PhD student at the Alfred Wagener Institute in Germany) examining their incubated samples for their nitrogen-uptake experiments on board the RV Investigator. Photo: Micheline Jenner AM.

 

The blue light the modular Isotope Laboratory aboard the RV Investigator, Cora Horstmann (PhD student at the Alfred Wagener Institute in Germany) prepares for nitrogen uptake experiments with Dr Eric Raes (CSIRO). Photo: Micheline Jenner AM.

Be sure to follow our daily Log from One Ten East at https://iioe-2.incois.gov.in or www.wamsi.org.au.

A Hard Day’s Night – One Ten East Log

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One Ten East Logs from the IIOE-2 voyage aboard RV Investigator will be posted on the WAMSI website during the month long voyage.

Log from One Ten East

The RV Investigator is currently undertaking oceanographic research along the 110°E meridian off Western Australia as part of the second International Indian Ocean Expedition. The voyage is led by Professor Lynnath Beckley of Murdoch University and the research is supported by a grant of sea time on RV Investigator from the CSIRO Marine National Facility.

Date: May 25, 2019 Time: 1200 AWST
Latitude: 27.5°S Longitude: 110°E
Wind direction: SE Wind speed:  knots
Swell direction: SSW Depth: 5651 m
Air temperature: 21.3°C Sea temperature: 22°C

Notes: All’s well as RV Investigator travels northwards into warmer air and seas, about 200nm west of the Abrolhos Islands.

A Hard Day’s Night

By Prof Lynnath Beckley

(Chief Scientist IN2019_V03)

Aboard the RV Investigator we are approaching the middle stations along our 110°E line and have proceeded from cool, temperate waters to warmer more subtropical waters. Operations are proceeding smoothly – watches swop with 12-hour regularity, equipment gets deployed, samples get taken as per the daily roster and we no longer really know which day of the week it is!

The ship operates on a 24/7 basis and most of the scientists are on 12-hour shifts, which rotate at 2am and 2pm. The 2am shift has a few hours of steaming until the ship reaches the location of the next station and, as we are approaching it, a sonobuoy is deployed, the Continuous Plankton recorder is retrieved, and by 7am the CTD is descending to the inky depths of the Indian Ocean. This takes several hours as the seafloor is generally deeper than 5,000 m! As the CTD returns to the surface, the Niskin bottles are fired to collect water at the different depths as per the water budget. When the CTD is back on board there is an intense period of emptying of the Niskin bottles so that everyone can get the water they require for samples and experiments.

While the water is dispensed, other scientists start with different activities. Initially, the Indian Ocean Standard Net is deployed so that it can sample zooplankton in the top 200m of the water column. After this, when the sun is hopefully high in the sky, the optics team swings into action deploying a range of equipment to measure the optical qualities of the water column. While this is happening, “lunch” is served – though it is not uncommon to see someone having cereal or Vegemite on toast as that time slot equates to their breakfast!

The 2pm to 2am watch starts with some netting action – the oblique tow for mesoplankton is followed by the 90-minute tow with the EZ net that yields stratified zooplankton samples in upper 500m of the water column. On the steam back to station the micro-zooplankton sampler is deployed and once back on station we use the fine-mesh Heron net for a vertical haul for the small zooplankton that are prey for the many larval fishes that we are catching. Then, the physical oceanographers get back into action and deploy the Vertical Mixing Profiler. And, as the sun sets over the Indian Ocean, it is time for “dinner” though for some it is now lunch!

Evening sampling commences with repeated tows of the surface neuston net to catch plankton that migrates to the surface at night. This entails factory-like activity in the laboratory as the contents of each tow are separated, identified and frozen for food web analyses or preserved for genetics. Then, another oblique mesoplankton haul before we settle in for an evening, shallow CTD (only 500m depth) from which most of the water is used for a series of on board incubation experiments. There is a further night-time vertical Indian Ocean Standard Net haul and then we are into another EZ net deployment with flashes of bioluminescence showing up on the screen as the denizens of the deep streak by. After 90 minutes, the net is back on deck and the samples start to be sorted and identified. Finally, the CPR is deployed out the stern and the RV Investigator is on its way to the next station up the 110°E line. Soon, the 2am watch will appear clutching their mugs of coffee and ready to see what the next station brings…

And, yes, it must be near the weekend as the footy tipping competition is in full swing!

Be sure to follow our daily Log from One Ten East at https://iioe-2.incois.gov.in or www.wamsi.org.au

Listening to the Sea – One Ten East Log

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One Ten East Logs from the IIOE-2 voyage aboard RV Investigator will be posted on the WAMSI website during the month long voyage.

Log from One Ten East

The RV Investigator is currently undertaking oceanographic research along the 110°E meridian off Western Australia as part of the second International Indian Ocean Expedition. The voyage is led by Professor Lynnath Beckley of Murdoch University and the research is supported by a grant of sea time on RV Investigator from the CSIRO Marine National Facility.

Date: May 24, 2019 Time:  1200 AWST
Latitude: 29°S Longitude: 110°E
Wind direction: SE Wind speed: 17 knots
Swell direction: SW Depth: 5589 m
Air temperature: 20°C Sea temperature: 21°C

Notes: As we travel northward along the line we are seeing a steady change from cool-temperate to sub-tropical conditions.

Listening to the Sea

By Capt Curt Jenner AM and Capt Micheline Jenner AM

For decades open ocean surveys for cetaceans have involved visual observations with field binoculars and identification guides. Using technology from World War 2, a new version of an old tool is currently assisting scientific surveys. Sonobuoys, underwater microphones (hydrophones) developed by the military, are now available for scientific research, such as those provided by the Australian Department of Defence for this project. Initially designed to detect enemy vessels by tracking acoustic “targets”, whale researchers can now track biological targets namely cetaceans (whales and dolphins), simply by listening for their calls. Presence and absence data, leading to abundance estimates, can be collected while transiting ocean basins. Amazingly, the listening strip width of acoustic surveys is 150 nautical miles or 280 km, which is 75 times more effective than the two nautical mile visual survey strip.

Each cetacean species creates unique calls, transmitting sounds on varying frequencies. Travelling the deep water of the south-east Indian Ocean with several daily sonobuoy deployments, the most prevalent acoustic detections by the Jenners so far, have been pygmy blue whale calls. At the first and most southern station, Antarctic blue, minke and fin whales were also recorded.

The IIOE-2 survey is providing new understanding regarding the characteristics of pygmy blue whale migration paths, particularly in concert with the collected oceanographic data. By tracking the direction of all the pygmy blue whale acoustic detections while RV Investigator moves northward along the 110°E line, the pygmy blue whale migration path towards Indonesian calving grounds, can be carefully documented. This is important because the presence or absence of animals such as whales, some of which feed low down on the food chain can lead to a better understanding of the health of the Indian Ocean. Are the blue whales travelling in large herds, individually or in twos and threes? Are they following specific isotherms (temperatures) while searching for productivity hotspots?

From the decks of RV Investigator, Curt and Micheline Jenner are keen to visually observe some migrating pygmy blue whales. So far the sounds are alluring… but actual sightings of the animals have been elusive. Thirty years of research has taught the whale team to remain hopeful!

Aboard RV Investigator from the 7th level observation deck, ten-minute seabird surveys each hour, during daylight hours are also being conducted by Curt and Micheline. Here Micheline Jenner is on the look out for Light-mantled sooty albatross, her favourite of the ocean soarers. The most frequently sighted seabirds so far have been Flesh-footed shearwaters, which breed on the islands off the west coast of Australia. Photo: Curt Jenner AM.

With the acoustic survey, plus visual observations for cetaceans and seabirds, three new data streams have been added to the wide range of oceanographic and biological research on this second International Indian Ocean Expedition voyage (IN2019_V03).

Be sure to follow our daily Log from One Ten East at https://iioe-2.incois.gov.in or www.wamsi.org.au.

Deep Sea Fishes – One Ten East Log

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One Ten East Logs from the IIOE-2 voyage aboard RV Investigator will be posted on the WAMSI website during the month long voyage.

 

We are directly west of Fremantle and today have enjoyed very calm conditions with a beautiful long swell.

 

 

 

Log from One Ten East

The RV Investigator is currently undertaking oceanographic research along the 110°E meridian off Western Australia as part of the second International Indian Ocean Expedition. The voyage is led by Professor Lynnath Beckley of Murdoch University and the research is supported by a grant of sea time on RV Investigator from the CSIRO Marine National Facility.

Date: May 23, 2019

Time:  1200 AWST

Latitude: 30.5°S

Longitude: 110°E

Wind direction: E    

Wind speed: 9.5 knots

Swell direction: W

Depth: 5392 m

Air temperature: 19°C

Sea temperature: 20°C

Notes: The night samples at Station 6 were jam-packed with phyllosoma (rock lobster) larvae, which had the zooplankton scientists grinning from ear to ear. The whole ship’s complement is enjoying the lovely calm weather.

 

Deep Sea Fishes

By Daniel Cohen and Dr M. Pilar Olivar

Deep-sea fishes reside at depths greater than 200 m beyond the effective influence of sunlight for most of the time. The mesopelagic zone (between 200–1000 m depths) is home to many diverse and bizarre fishes, such as dragonfishes, snaketooths, bristlemouths, hatchetfishes, lightfishes and lanternfishes. The early stages of these fishes develop in the epipelagic layer nearer to the surface, but juveniles and adults move down into the dark zone. Some families are characterized by performing diel vertical migrations through the water column (e.g., lanternfishes), while others (e.g., bristlemouths or hatchetfishes) remain in the dark part of the ocean all the time.

Species of the family Myctophidae (lanternfish) are the dominant migrating mesopelagic fishes, and they constitute the focus of our studies on this voyage.  Adult myctophids are small (from 3 to 10 cm) and have some similarity in appearance to an anchovy, although being darker in color and characterized by the presence of small luminous organs on their bodies. Their larvae are small (from 2 to 15 mm) and transparent, similar to those of many other fish species. Myctophid larvae generally dominate plankton samples from the deep open ocean.

Worldwide, lanternfish comprise about 250 species and account for 65% of mesopelagic fish biomass. The name myctophid comes from the Greek word “mykter” meaning nose and “ophis” meaning serpent, while the common name lanternfish describes the array of light emitting organs called photophores that occur in species-specific patterns on their bodies.

In a laboratory aboard RV Investigator Dr Pilar Olivar (Institute of Marine Science, Barcelona) identifies deep sea fishes using a dissecting microscope with a camera and image capture capability, while Danielle Hodgkinson (Murdoch University) carefully labels the samples before preservation. Photo: Micheline Jenner.

 

Hatchet fish are the most well-recognised of the deep sea fishes, with their large over-sized jaws, bulgy eye and silver jacket. Photo: Micheline Jenner.

 

Living in the light-limited mesopelagic zone means little access to prey. Myctophids deal with this problem by performing diel vertical migration, being the movement up into the plankton rich surface waters at night to feed, before returning to the safety of the deep during the day. In this way, myctophids occupy an important position in the oceanic food web transporting organic matter vertically through their migrations and providing food for larger predatory species.

Despite their importance, relatively little is known about myctophids in the south-east Indian Ocean and this is largely due to the difficulty in sampling deep-sea fishes. Fortunately, thanks to their diel vertical migration at night, when they are feeding near the surface, these fishes can be captured using large nets towed from research vessels. Additionally, the presence of their larval stages nearer to the surface allows sampling by means of standard plankton nets, and an indirect way of studying species distribution, abundance and diversity. Lanternfishes, through their abundance, play a vital role in the health and functioning of the ocean, particularly because they are prey for commercially important species such as tuna, mackerel and squid and ecologically significant species such as seabirds and whales.

 

Daniel Cohen (Murdoch University Honours Student) sorts myctophid fishes from the depth-stratified EZ net tows. Photo: Micheline Jenner.

 

Larvae of some deep sea fishes bear little resemblance to the adults. Here, an Idiacanthus fasiola larva has “eyes on stalks”, whilst the adult is more normal in appreance! Photo: Dr Pilar Olivar.

 

Be sure to follow our daily Log from One Ten East at https://iioe-2.incois.gov.in or www.wamsi.org.au.

Deep Sea Fishes – One Ten East Log

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One Ten East Logs from the IIOE-2 voyage aboard RV Investigator will be posted on the WAMSI website during the month long voyage.

We are directly west of Fremantle and today have enjoyed very calm conditions with a beautiful long swell.

Log from One Ten East

The RV Investigator is currently undertaking oceanographic research along the 110°E meridian off Western Australia as part of the second International Indian Ocean Expedition. The voyage is led by Professor Lynnath Beckley of Murdoch University and the research is supported by a grant of sea time on RV Investigator from the CSIRO Marine National Facility.

Date: May 23, 2019 Time:  1200 AWST
Latitude: 30.5°S Longitude: 110°E
Wind direction: E Wind speed: 9.5 knots
Swell direction: W Depth: 5392 m
Air temperature: 19°C Sea temperature: 20°C

Notes: The night samples at Station 6 were jam-packed with phyllosoma (rock lobster) larvae, which had the zooplankton scientists grinning from ear to ear. The whole ship’s complement is enjoying the lovely calm weather.

Deep Sea Fishes

By Daniel Cohen and Dr M. Pilar Olivar

Deep-sea fishes reside at depths greater than 200 m beyond the effective influence of sunlight for most of the time. The mesopelagic zone (between 200–1000 m depths) is home to many diverse and bizarre fishes, such as dragonfishes, snaketooths, bristlemouths, hatchetfishes, lightfishes and lanternfishes. The early stages of these fishes develop in the epipelagic layer nearer to the surface, but juveniles and adults move down into the dark zone. Some families are characterized by performing diel vertical migrations through the water column (e.g., lanternfishes), while others (e.g., bristlemouths or hatchetfishes) remain in the dark part of the ocean all the time.

Species of the family Myctophidae (lanternfish) are the dominant migrating mesopelagic fishes, and they constitute the focus of our studies on this voyage.  Adult myctophids are small (from 3 to 10 cm) and have some similarity in appearance to an anchovy, although being darker in color and characterized by the presence of small luminous organs on their bodies. Their larvae are small (from 2 to 15 mm) and transparent, similar to those of many other fish species. Myctophid larvae generally dominate plankton samples from the deep open ocean.

Worldwide, lanternfish comprise about 250 species and account for 65% of mesopelagic fish biomass. The name myctophid comes from the Greek word “mykter” meaning nose and “ophis” meaning serpent, while the common name lanternfish describes the array of light emitting organs called photophores that occur in species-specific patterns on their bodies.

Living in the light-limited mesopelagic zone means little access to prey. Myctophids deal with this problem by performing diel vertical migration, being the movement up into the plankton rich surface waters at night to feed, before returning to the safety of the deep during the day. In this way, myctophids occupy an important position in the oceanic food web transporting organic matter vertically through their migrations and providing food for larger predatory species.

Despite their importance, relatively little is known about myctophids in the south-east Indian Ocean and this is largely due to the difficulty in sampling deep-sea fishes. Fortunately, thanks to their diel vertical migration at night, when they are feeding near the surface, these fishes can be captured using large nets towed from research vessels. Additionally, the presence of their larval stages nearer to the surface allows sampling by means of standard plankton nets, and an indirect way of studying species distribution, abundance and diversity. Lanternfishes, through their abundance, play a vital role in the health and functioning of the ocean, particularly because they are prey for commercially important species such as tuna, mackerel and squid and ecologically significant species such as seabirds and whales.

Be sure to follow our daily Log from One Ten East at https://iioe-2.incois.gov.in or www.wamsi.org.au.

Transparent Marine Animals – One Ten East Log

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One Ten East Logs from the IIOE-2 voyage aboard RV Investigator will be posted on the WAMSI website during the month long voyage.

 

 

 

 

 

 

Log from One Ten East

The RV Investigator is currently undertaking oceanographic research along the 110°E meridian off Western Australia as part of the second International Indian Ocean Expedition. The voyage is led by Professor Lynnath Beckley of Murdoch University and the research is supported by a grant of sea time on RV Investigator from the CSIRO Marine National Facility.

 

Date: May 22, 2019

Time:  1200 AWST

Latitude: 32°S

Longitude: 110°E

Wind direction: WSW         

Wind speed: 3 knots

Swell direction: SW

Depth: 5163 m

Air temperature: 17°C

Sea temperature: 19.5°C

Notes: What a beautiful day! The samples are full of rock lobster larvae (phyllosoma) and two pygmy blue whales are belting out low frequency calls. Are they looking for a dinner date?

 

Transparent Marine Animals

By Andrew Jeffs

Living in the clear waters of the open ocean is a dangerous business when you are a small swimming organism because there is nowhere to hide from predators. However, many marine creatures have evolved a clever way to overcome the lack of hiding places. They have evolved to make their bodies transparent–so they are almost invisible in the seawater. Having a transparent body can also be handy if you are a predator, as it helps for sneaking up on your prey unseen. Many different types of open ocean organisms have evolved to become transparent including fish, crustaceans, worms, jellyfish and squid. In fact, in some areas of the open ocean, over 90% of the organisms larger than a full stop, are transparent. Despite the prevalence of this phenomenon, it is not well known how these organisms achieve transparency, particularly requiring body tissues that do not absorb or bend light. Whilst on board the RV Investigator in the Indian Ocean we are capturing different types of small transparent ocean organisms in nets and then using laser beams to measure how well their bodies match the optical properties of the surrounding seawater, in order to achieve transparency.

 

Prof Andrew Jeffs (University of Auckland) shines a light on a plankton sample collected from the RV Investigator, while Daniel Cohen (Murdoch University Honours student) selects a transparent rock lobster larva for further examination.

 

A transparent rock lobster phyllosoma larva, which drift in the open ocean for nearly a year before metamorphosing and settling near the coast. Photo: Prof Lynnath Beckley.

 

Overall, from the range of nets we are using (and a lot of microscope work), we can quantify zooplankton in the south-east Indian Ocean, process this information in food web analyses and include the data in models of ocean functioning.

Be sure to follow our daily Log from One Ten East at https://iioe-2.incois.gov.in or www.wamsi.org.au.

Transparent Marine Animals – One Ten East Log

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One Ten East Logs from the IIOE-2 voyage aboard RV Investigator will be posted on the WAMSI website during the month long voyage.

Log from One Ten East

The RV Investigator is currently undertaking oceanographic research along the 110°E meridian off Western Australia as part of the second International Indian Ocean Expedition. The voyage is led by Professor Lynnath Beckley of Murdoch University and the research is supported by a grant of sea time on RV Investigator from the CSIRO Marine National Facility.

Date: May 22, 2019 Time:  1200 AWST
Latitude: 32°S Longitude: 110°E
Wind direction: WSW Wind speed: 3 knots
Swell direction: SW Depth: 5163 m
Air temperature: 17°C Sea temperature: 19.5°C

Notes: What a beautiful day! The samples are full of rock lobster larvae (phyllosoma) and two pygmy blue whales are belting out low frequency calls. Are they looking for a dinner date?

Transparent Marine Animals

By Andrew Jeffs

Living in the clear waters of the open ocean is a dangerous business when you are a small swimming organism because there is nowhere to hide from predators. However, many marine creatures have evolved a clever way to overcome the lack of hiding places. They have evolved to make their bodies transparent–so they are almost invisible in the seawater. Having a transparent body can also be handy if you are a predator, as it helps for sneaking up on your prey unseen. Many different types of open ocean organisms have evolved to become transparent including fish, crustaceans, worms, jellyfish and squid. In fact, in some areas of the open ocean, over 90% of the organisms larger than a full stop, are transparent. Despite the prevalence of this phenomenon, it is not well known how these organisms achieve transparency, particularly requiring body tissues that do not absorb or bend light. Whilst on board the RV Investigator in the Indian Ocean we are capturing different types of small transparent ocean organisms in nets and then using laser beams to measure how well their bodies match the optical properties of the surrounding seawater, in order to achieve transparency.

Overall, from the range of nets we are using (and a lot of microscope work), we can quantify zooplankton in the south-east Indian Ocean, process this information in food web analyses and include the data in models of ocean functioning.

Be sure to follow our daily Log from One Ten East at https://iioe-2.incois.gov.in or www.wamsi.org.au.

Net Benefits – One Ten East Log

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One Ten East Logs from the IIOE-2 voyage aboard RV Investigator will be posted on the WAMSI website during the month long voyage.

 

Log from One Ten East

The RV Investigator is currently undertaking oceanographic research along the 110°E meridian off Western Australia as part of the second International Indian Ocean Expedition. The voyage is led by Professor Lynnath Beckley of Murdoch University and the research is supported by a grant of sea time on RV Investigator from the CSIRO Marine National Facility.

 

Date: May 21, 2019

Time:  1200 AWST

Latitude: 33.5°S

Longitude: 110°E

Wind direction: WSW 

Wind speed: 12 knots

Swell direction: WSW

Depth: 2644 m

Air temperature: 15.2°C

Sea temperature: 18.2 °C

Notes: The wind is calming and the sky clearing as RV Investigator traverses the Naturaliste Plateau. The scientists are happy as the sample jars are being dutifully labelled and filled.

 

Net Benefits

By Prof Lynnath Beckley

 

The word plankton is derived from the Greek word ‘planktos’ meaning drifter. Planktonic organisms generally drift in the ocean but some can undertake limited swimming to achieve vertical migration from the depths towards the surface to feed at night.

On our voyage with the RV Investigator, along the 110°E meridian in the south-east Indian Ocean, in addition to filtering very tiny organisms from water samples, we are using a wide variety of nets to capture plankton. These range from a tiny net with 20-micron mesh to catch phytoplankton to a large net with 1000-micron (=1 mm) mesh to catch larger zooplankton like krill, and the larvae of fish and rock lobsters.

One of the most historically significant nets we are using is the Indian Ocean Standard Net. We have a specially built replica of the original nets deployed by 14 different ships during the first Indian Ocean Expedition in the 1960s to compare the biomass (weight) of zooplankton in the surface 200m of the water column across the ocean basin. We are replicating these vertical hauls at the same time of the year and locations along the 110°E meridian to ascertain if there are any major differences in the biomass and composition of the zooplankton between the two voyages.

The Indian Ocean Standard Net (IOSN) is the one of the original nets used in the International Indian Ocean Expedition. This one used on the IIOE-2 is a replica allowing for interesting comparisons across the 60 years or so since the first voyage. Photo: Micheline Jenner.

 

Dr David Tranter, formerly of CSIRO, and now well-retired, led the Australian plankton research during the first expedition and was responsible for numerous publications revealing the composition and abundance of zooplankton in the south-east Indian Ocean. He and his wife, Helen, even went to live in India for a while to train scientists at the Indian Ocean Biological Centre to process and identify the over 2000 zooplankton samples that were collected by nine countries during the first expedition.

 

Dr David Tranter and Prof Lynnath Beckley comparing notes on Indian Ocean zooplankton prior to the 2019 voyage. Photo: Dr Tony Miskiewicz.

 

Other equipment that is particularly useful for elucidating plankton is the EZ multiple opening and closing net. This consists of ten 500-micron nets in a big frame and they are electronically opened and closed at different depths in the ocean to sample the zooplankton. This enables comparison of the depths that various zooplankton reside during the day and night and allows us to quantify zooplankton abundance in different depth zones.

 

The EZ net being deployed from the A-frame of RV Investigator on the aft deck by the experienced deck crew. The EZ net comprises a rectangular frame holding ten nets, each of which are closed remotely at various depths. Photo: Micheline Jenner.

 

 

 

Opening and closing the EZ net at different depth strata are Ian McRobert, Prof Lynnath Beckley (Murdoch University) and Pilar Olivar (IMS, Barcelona) in the Operations Room on board RV Investigator. Photo: Micheline Jenner.

 

 

The camera view looking into the EZ net shows the mechanism for obtaining fishes from different strata. In the centre of the image, the “bar” across the centre is one of the frames of one of the nets. Photo: Micheline Jenner.

 

Overall, from the range of nets we are using (and a lot of microscope work), we can quantify zooplankton in the south-east Indian Ocean, process this information in food web analyses and include the data in models of ocean functioning.

 

Be sure to follow our daily Log from One Ten East at https://iioe-2.incois.gov.in or www.wamsi.org.au.

Net Benefits – One Ten East Log

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One Ten East Logs from the IIOE-2 voyage aboard RV Investigator will be posted on the WAMSI website during the month long voyage.

Log from One Ten East

The RV Investigator is currently undertaking oceanographic research along the 110°E meridian off Western Australia as part of the second International Indian Ocean Expedition. The voyage is led by Professor Lynnath Beckley of Murdoch University and the research is supported by a grant of sea time on RV Investigator from the CSIRO Marine National Facility.

Date: May 21, 2019 Time:  1200 AWST
Latitude: 33.5°S Longitude: 110°E
Wind direction: WSW Wind speed: 12 knots
Swell direction: WSW Depth: 2644 m
Air temperature: 15.2°C Sea temperature: 18.2 °C

Notes: The wind is calming and the sky clearing as RV Investigator traverses the Naturaliste Plateau. The scientists are happy as the sample jars are being dutifully labelled and filled.

Net Benefits

By Prof Lynnath Beckley

The word plankton is derived from the Greek word ‘planktos’ meaning drifter. Planktonic organisms generally drift in the ocean but some can undertake limited swimming to achieve vertical migration from the depths towards the surface to feed at night.

On our voyage with the RV Investigator, along the 110°E meridian in the south-east Indian Ocean, in addition to filtering very tiny organisms from water samples, we are using a wide variety of nets to capture plankton. These range from a tiny net with 20-micron mesh to catch phytoplankton to a large net with 1000-micron (=1 mm) mesh to catch larger zooplankton like krill, and the larvae of fish and rock lobsters.

One of the most historically significant nets we are using is the Indian Ocean Standard Net. We have a specially built replica of the original nets deployed by 14 different ships during the first Indian Ocean Expedition in the 1960s to compare the biomass (weight) of zooplankton in the surface 200m of the water column across the ocean basin. We are replicating these vertical hauls at the same time of the year and locations along the 110°E meridian to ascertain if there are any major differences in the biomass and composition of the zooplankton between the two voyages.

Dr David Tranter, formerly of CSIRO, and now well-retired, led the Australian plankton research during the first expedition and was responsible for numerous publications revealing the composition and abundance of zooplankton in the south-east Indian Ocean. He and his wife, Helen, even went to live in India for a while to train scientists at the Indian Ocean Biological Centre to process and identify the over 2000 zooplankton samples that were collected by nine countries during the first expedition.

Other equipment that is particularly useful for elucidating plankton is the EZ multiple opening and closing net. This consists of ten 500-micron nets in a big frame and they are electronically opened and closed at different depths in the ocean to sample the zooplankton. This enables comparison of the depths that various zooplankton reside during the day and night and allows us to quantify zooplankton abundance in different depth zones.

Overall, from the range of nets we are using (and a lot of microscope work), we can quantify zooplankton in the south-east Indian Ocean, process this information in food web analyses and include the data in models of ocean functioning.

Be sure to follow our daily Log from One Ten East at https://iioe-2.incois.gov.in or www.wamsi.org.au.

Micro- and Mesozooplankton – One Ten East Log

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One Ten East Logs from the IIOE-2 voyage aboard RV Investigator will be posted on the WAMSI website during the month long voyage.

We had a couple of fronts blow through today, but the 27-30 knots of wind and blustery rain did not hinder the wonderful work of the deck crew. All the nets were deployed and retrieved carefully and efficiently. 

There is blue sky ahead but even in the slightly blustery conditions, the company of Wandering and Black-browed Albatross at Station 3 was appreciated.

 

Log from One Ten East

The RV Investigator is currently undertaking oceanographic research along the 110°E meridian off Western Australia as part of the second International Indian Ocean Expedition. The voyage is led by Professor Lynnath Beckley of Murdoch University and the research is supported by a grant of sea time on RV Investigator from the CSIRO Marine National Facility.

Date: May 20, 2019

Time:  1200 AWST

Latitude: 35°S

Longitude: 110°E

Wind direction: WSW         

Wind speed: 23 knots 

Swell direction: W

Depth: 4911 m

Air temperature: 14.8°C

Sea temperature: 18.3°C

Notes: The rain has cleared and there are patches of blue sky all around! Rock lobster larvae (phyllosoma) were caught in the surface nets last night and pygmy blue whales were heard calling in the east.

 

Micro- and Mesozooplankton

By Michael Landry

Planktonic consumers can be divided into two major size classes, the micro- and mesozooplankton, depending on whether they pass through or are retained on 200-µm mesh sieve. The mesozooplankton consists mainly of true multicellular animals, like copepods, euphausiids (krill) and chaetognaths (arrow worms), that are concentrated and collected by towing a plankton net with 200-µm mesh through the water. In contrast, the microzooplankton (<200 µm) category contains mainly protozoans (single-cell flagellates and ciliates) with some very small animals and is best collected by preserving water samples without prior net concentration.

Schematic of an oceanic food web. Credit:  Steinberg & Landry (2017)

 

Both micro- and mesozooplankton are diverse assemblages of organisms with varying life strategies and feeding preferences, but they are associated with different functions in ocean food webs. Microzooplankton are typically the main consumers of phytoplankton and bacteria, especially in regions where the dominant phytoplankton Mesozooplankton, on the other hand, are the main food web link to higher level animals (fishes), and they are associated with mechanisms (daily migrations, rapidly sinking fecal pellets) that move organically fixed carbon and nutrients out of the euphotic zone and into deeper layers of the ocean. Studying how ocean systems differ in terms of how productivity moves through micro- versus mesozooplankton is therefore a basic approach to characterizing their different relative functions in nutrient recycling, trophic transfers and carbon export.

Prof Michael Landry (Scripps Institution of Oceanography and Sir Walter Murdoch Distinguished Collaborator), with his mesozooplankton net on the aft deck of RV Investigator. Note, the flowmeter which allows quantification of abundance of plankton per cubic metre of seawater. Photo: Micheline Jenner.

 

Claire Davies (IMOS/CSIRO) fractionates the plankton sample from the 200-µm net through a range of sieves to determine the abundance of different-sized organisms in the zooplankton. Photo: Micheline Jenner.

 

Prof Michael Landry (Scripps Institution of Oceanography) gently lifts a filter paper containing small mesozooplankton. Photo: Micheline Jenner.

 

After fractionation, the different-sized organisms in the plankton are revealed. From left to right, large zooplankton (e.g. chaetognath here) retained on a coarse mesh, through to copepods retained on the fine 200-µm mesh. Photo: Micheline Jenner.

 

Be sure to follow our daily Log from One Ten East at https://iioe-2.incois.gov.in or www.wamsi.org.au