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 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

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 .

 

 

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

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.

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.

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).

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.

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

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 16, 2019	Time: 1200 AWST
Latitude: 37.143° S	Longitude: 111.712° E
Wind direction: 182° (S)	Wind speed: 22 knots
Swell direction: SE, S	Depth: 5,176 m
Air temperature: 11.5°C	Sea temperature: 16.0°C

Notes: Ship steaming to the first station of the 110°East line, albatrosses soaring and Antarctic and pygmy blue whales calling.

By Helen Phillips

The most reliable way we have to track global warming is by measuring the change in temperature in the ocean. This is because the ocean is absorbing more than 90% of the extra heat. Most of the global warming heat is in the upper 1000 m of the ocean. However, around Antarctica, the surface waters become saltier and heavier as sea ice forms in winter, and they sink all the way to the bottom of the ocean. These Antarctic Bottom Waters spread northward filling the deepest parts of the ocean, including the Indian Ocean, contributing to sea level rise as they warm.

The best way to measure the deep ocean below 2000 m is using a CTD–a Conductivity, Temperature and Depth profiler, lowered from a research vessel. The electronic sensors of the CTD are positioned within a large frame (the rosette) around which are 36 12-litre bottles that are used to capture water at different depths. This water is extremely valuable to the scientists on board as direct chemical analysis in our laboratory is the primary way to measure some water properties and also provides a critical check on the accuracy of the electronic measurements. Biological studies also need actual samples of water to identify tiny microbes in the water. This labour-intensive, costly work means that measurements in the deep ocean are infrequent and sparsely distributed.

On the first International Indian Ocean Expedition in the 1960s, the CTD was not yet invented, but bottles could be lowered to collect water samples at specific depths, and a reversing thermometer was used to record the temperature at depth. So there are measurements of the properties of the bottom waters from the 1960s. Sixty years later, our new measurements will reveal how rapidly the changes already detected around Antarctica have progressed into the Indian Ocean, and will help to guide our predictions of future warming and sea level rise. In addition to bottom water changes, we will be able to measure changes at all levels, not only in temperature but in the chemical composition and biological diversity, as well.

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