Transparent Marine Animals – One Ten East Log

This article was originally published on an archived WAMSI website. Some media or links may appear missing or broken. You can use the search function to look for these, or contact info@wamsi.org.au for a specific request.

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

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

This article was originally published on an archived WAMSI website. Some media or links may appear missing or broken. You can use the search function to look for these, or contact info@wamsi.org.au for a specific request.

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

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

This article was originally published on an archived WAMSI website. Some media or links may appear missing or broken. You can use the search function to look for these, or contact info@wamsi.org.au for a specific request.

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

Phytoplankton and Pigments – One Ten East Log

This article was originally published on an archived WAMSI website. Some media or links may appear missing or broken. You can use the search function to look for these, or contact info@wamsi.org.au for a specific request.

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 have had another great day and have almost completed Station 2 on the 110 East line.

It has been a little cloudy and a little breezier today but the flesh-footed shearwaters are happily gliding just above the waves. Everyone is getting into the swing of having their nets deployed and retrieved and the sample jars are being dutifully labelled and nicely filled!

 

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 19, 2019 Time:  1200 AWST
Latitude: 36.5°S Longitude: 110°E
Wind direction: NNW Wind speed: 27 knots
Swell direction: SW Depth: 5365 m
Air temperature: 16°C Sea temperature: 15.3°C
Notes: It’s a bit rainy and soggy today but this is not dampening the spirits of the scientists aboard RV Investigator! This morning we completed our deepest CTD to date, at over 5 km depth.

 

Phytoplankton & Pigments

By David Antoine and Martina Doblin

Phytoplankton–the microscopic plants inhabiting the surface lit layers of the ocean are among the most diverse group of micro-organisms inhabiting the planet. They comprise eight main groups, have individual cell sizes from less than a micron to about one millimeter (see Figure below) and play various roles in the ecosystem. As they photosynthesize, they collectively represent the first link of the marine food web. All phytoplankton contain the pigment chlorophyll-a, which is measured to ascertain phytoplankton biomass. As well as chlorophyll-a, each phytoplankton group has other accessory pigments, which can be used to determine phytoplankton groups or size classes. Phytoplankton are also responsible for the transfer of carbon dioxide from the atmosphere to the deep layers of the ocean and ultimately the sediments of the sea floor.

Fig 1. An indication of the scale of phytoplankton size in microns relative to larger biota and recognisable land features in metres. Source : Finkel et al. 2010. J. Plank. Res. 32(1), 119-137.

 

Peta Vine (University of Technology Sydney) using the large filtration rack to separate phytoplankton and their associated pigments from water samples collected at different depths with the CTD Niskin bottles. Photo: Micheline Jenner.

 

After the water has been filtered the pigments remain on the small filter papers and here, Peta Vine (University of Technology Sydney) points to a filter with pigments, in comparison to the adjacent clean filter. Photo: Micheline Jenner.

 

Examples of phytoplankton from the south-east Indian Ocean. Top: A diatom chain clearly showing green chlorophyll and a stunning Chaetoceros sp. photographed under a microscope from water samples collected from the RV Investigator on the 110°East line. Photo: Dr Peter Thompson.

 

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

Tiny Microbes, Big Impact – One Ten East Log

This article was originally published on an archived WAMSI website. Some media or links may appear missing or broken. You can use the search function to look for these, or contact info@wamsi.org.au for a specific request.

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 have had another fantastic day in the Indian Ocean aboard RV Investigator. The CTD was deployed early in the morning and with a calm sea and light wind, the first station on the 110 East line was successfully completed. Micro and macro zooplankton have been collected with various nets, the CTD rosette was lowered twice and from those water samples, nutrients and microbes have been sampled for analysis.

We even had a minke whale sighted not too far from the ship and then two fin whales passed the starboard side and then across the bow! We have plankton and whales, life is good!

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 18, 2019

Time:  1200 AWST

Latitude: 38°S

Longitude: 110°E

Wind direction: N    

Wind speed:  15 knots

Swell direction: SW

Depth:  4266 m

Air temperature: 13.7°C

Sea temperature: 13.8°C

Notes: Station 1 is done and dusted. It was a very busy day with lots of samples and data collected by many satisfied scientists.

 

Tiny Microbes, Big Impact

By Dr Martin Ostrowski

Microbes are everywhere, they’re in the soil, on our skin, in our guts and they live in the ocean in incredible numbers. In a similar role to our gut microbes, which are keeping us healthy, research has revealed that ocean microbes play important roles sustaining our planet. What are these microbes and what are they doing? Onboard RV Investigator a team of microbiologists is addressing these questions using modern molecular methods. They aim to identify which microbes are present and determine how they thrive and interact with other species. This work will help us understand how these tiny organisms support the production of food in the ocean, which feeds over 1 billion people, and ultimately plays a fundamental role keeping our planet healthy. 

Most marine microbes are planktonic, but surprisingly, they fundamentally shape their surroundings by transforming over 90% of all organic matter, driving major elemental and geochemical cycles, and making and breaking chemical compounds that have a direct effect on climate. What they lack in size, they make up for in sheer numbers.

The activity of microbes impacts on all levels of the marine systems, from water chemistry and primary production, which ultimately supports all marine life, through to regulating climate and playing a role in the health of the largest mammals on the planet. Over geological time, free-living marine microbes have been the main source of power for the planet. By modern estimates, approximately half of all primary production occurs in the oceans. In very general terms, this means that marine microbes are like the lungs of the planet, but in reverse, drawing in carbon dioxide and releasing oxygen for us to breathe.

 

In the CTD room, several scientists retrieve water samples from the Niskin bottles for microbial analyses. In the foreground from left, Amaranta Focardi (Macquarie University) documenting the details and James O’Brien (University of Technology Sydney) and Dr Peter Thompson (CSIRO) taking water from the rosette. Photo: Micheline Jenner.

 

Microbes are invisible to the naked eye, especially the single-celled species, which make up the bulk of ‘biomass’ in the oceans. Much of the work done in the microbiology lab involves flow cytometry and high-throughput genome sequencing of water samples collected from different depths using the CTD rosette of Niskin bottles. We use the cytometer to count different types of bacteria, cyanobacteria, micro algae and virus particles. There are more than one million microbial cells in each millilitre of seawater, and 10 times more viruses! Sequencing of microbial marker genes provides estimates of total diversity in the Australian marine microbiome.

 

 

Pramita Ranjit (Macquarie University) filters water in one of the laboratories on the RV Investigator to determine the microbiome of the south-east Indian Ocean at the first station on the 110° East line. 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

 

Indian Ocean Nutrients – One Ten East Log

This article was originally published on an archived WAMSI website. Some media or links may appear missing or broken. You can use the search function to look for these, or contact info@wamsi.org.au for a specific request.

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

The wind and swell was up a little yesterday. This seemed to keep a few participants in their bunks a bit longer in the morning but by evening, most were feeling fine again. Fortunately, this was a transit day and the weather has improved as we have begun the first station on 110 East meridian. 

The yellow-nosed and black-browed Albatross were soaring beautifully in the fresh 20-30 kts and all is well on the fine RV Investigator.

 

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 17, 2019

Time:  1200 AWST

Latitude: 39.5°S

Longitude: 110°E

Wind direction: NNW 

Wind speed: 10 knots

Swell direction: SSW

Depth: 4600 m

Air temperature: 9.6°C

Sea temperature: 12.6°C

Notes: Five species of albatrosses, cape petrels and a minke whale sighted today. The galley is providing wonderful food for a hungry and appreciative crew!

Indian Ocean Nutrients

By Dr Peter Thompson

The CSIRO scientists involved in the original International Indian Ocean Expedition during the 1960s described it as a desert. Huge regions of the Indian Ocean had almost no plant life. The thousands of species and billions of microscopic plants found in most oceans were largely absent. These plants, just like the ones in your garden or paddock, require nutrients to grow. In the garden, we add fertiliser with these nutrients, particularly nitrogen and phosphorus, to ensure a successful crop. These nutrients are in very short supply in the surface waters of the Indian Ocean.

To find out how much nutrient is present it is necessary to get samples of water from deep in the ocean. Special tubular containers, called Niskin bottles, located on the CTD are sent down with the ends open (can you guess why?) on a wire to depths of 5000 m where they are electronically triggered to close and collect the samples. Several hours later when the bottles are winched back to the surface the chemists can start the process of measuring the nutrients. To do this we use sophisticated on board instruments and internationally agreed high precision methods. It is a bit like a blood test to check the health of the ocean.

Dr Peter Thompson (CSIRO) and Dr Karlie McDonald (CSIRO) take water from two of the 36 Niskin bottles in the CTD rosette, to analyse nutrient levels of the south-east Indian Ocean. Photo: Micheline Jenner.

 

In the nearly 60 years since the first International Indian Ocean Expedition we have learned much about the cycling of nutrients in the ocean. A thousand meters below the surface where the water is only 5°C, nitrate is plentiful (Figure 1). However, enough light for plants to grow only penetrates to about 100 m where nitrate is particularly scarce. Processes that we did not understand in the 1960s, we now know are changing the supply of nutrients to the surface and some parts of the Indian Ocean are becoming more productive (more nutrients = more plants = more fish) while others are less productive. On this second voyage (IIOE-2) we are exploring how nutrient supply has changed over the last six decades in the Indian Ocean offshore of Western Australia.

Figure 1. Plots of temperature, light and nitrate in the upper water column. Temperature declines slowly with depth but light disappears dramatically at about 100 m depth in the open Indian Ocean. The amounts of nutrients, such as nitrate, are very low until around 200 m depth. Data courtesy of CSIRO.

 

In particular, we are looking for evidence of changes in nutrients within the deep ocean as a result of changing global ocean circulation patterns. This mix of deep and shallow circulation brings deep nutrients from the North Atlantic and some nutrients from the Pacific into the Indian Ocean (Figure 2).

 

Figure 2. The global ocean and its thermo-haline circulation bring nutrients from deep regions in the North Atlantic and the surface of the Pacific into the Indian Ocean. Image courtesy of NASA/JPL.

These processes are changing faster than ever due to global warming. In addition, we will investigate nutrient recycling near the surface of the ocean. There, an expanding area of low oxygen is impacting on the microbial processes that recycle organic matter. Understanding the impacts of these changes on the ecology of the Indian Ocean is one of the key goals of the 110° East voyage.

Dr Peter Hughes (CSIRO) in the hydro-chemistry lab aboard RV Investigator uses sophisticated and precise equipment to measure chemical composition of the water sampled by the CTD. 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 .

 

 

Micro- and Mesozooplankton – One Ten East Log

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.

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.

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

Phytoplankton and Pigments – One Ten East Log

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 have had another great day and have almost completed Station 2 on the 110 East line.

It has been a little cloudy and a little breezier today but the flesh-footed shearwaters are happily gliding just above the waves. Everyone is getting into the swing of having their nets deployed and retrieved and the sample jars are being dutifully labelled and nicely filled!

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 19, 2019 Time:  1200 AWST
Latitude: 36.5°S Longitude: 110°E
Wind direction: NNW Wind speed: 27 knots
Swell direction: SW Depth: 5365 m
Air temperature: 16°C Sea temperature: 15.3°C

Notes: It’s a bit rainy and soggy today but this is not dampening the spirits of the scientists aboard RV Investigator! This morning we completed our deepest CTD to date, at over 5 km dept

Phytoplankton & Pigments

By David Antoine and Martina Doblin

Phytoplankton–the microscopic plants inhabiting the surface lit layers of the ocean are among the most diverse group of micro-organisms inhabiting the planet. They comprise eight main groups, have individual cell sizes from less than a micron to about one millimeter (see Figure below) and play various roles in the ecosystem. As they photosynthesize, they collectively represent the first link of the marine food web. All phytoplankton contain the pigment chlorophyll-a, which is measured to ascertain phytoplankton biomass. As well as chlorophyll-a, each phytoplankton group has other accessory pigments, which can be used to determine phytoplankton groups or size classes. Phytoplankton are also responsible for the transfer of carbon dioxide from the atmosphere to the deep layers of the ocean and ultimately the sediments of the sea floor.

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