Tracking Sulphur Cycling Microbes in the Indian Ocean – 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.

Notes: Today it is sunny with the wind abating and this is making the optics group very happy!

Tracking Sulphur Cycling Microbes in the Indian Ocean

By Justin Seymour

Although inconspicuous, microbes are the most abundant and diverse organisms in the ocean. Microbes form the base of the marine food web, while their metabolic activities control the chemical transformations that regulate ocean nutrient cycles and global climate.

Among these important chemical cycles is the ocean’s sulphur cycle, which is governed by several important groups of marine microbes. Sulphur is an essential element for all living organisms, while some sulphur compounds are also key components within the chemical cycles that control climatic processes. Specifically, a compound called DMSP (dimethyl sulphoniopropionate) is produced by several species of phytoplankton, which use it for various metabolic functions. DMSP is also an essential resource for marine bacteria, which obtain a significant proportion of their carbon and sulphur requirements from this compound. However, not all bacteria use DMSP in the same way, and this can have a big impact on the chemical cycling processes that influence our climate.

While some bacteria use the sulphur in DMSP to support their growth, others convert the DMSP into another important sulphur molecule called DMS (dimethylsulphide). The relative importance of these two bacterial pathways is significant, because DMS is a gas that is emitted from the ocean into the atmosphere, where it is converted into cloud condensation nuclei, which influence regional climate.

James O’Brien (PhD student University of Technology Sydney) filtering seawater samples for sulphur microbes. Photo: Micheline Jenner AM.

Amaranta Forcardi (PhD student Macquarie University) doing the long 12-hour filtration for viruses. Photo: Micheline Jenner AM.

We currently have a very limited understanding of the environmental factors that govern these different microbial-controlled DMSP transformation pathways and how the microbiological characteristics of seawater can ultimately influence climate. Our team, led by James O’Brien and Justin Seymour from the University of Technology Sydney, are using a combination of molecular microbiology and analytical chemistry tools (gas chromatograph) to track the biological drivers of sulphur cycling in the Indian Ocean. The latitudinal extent of this voyage is enabling us to determine how different oceanographic conditions govern these globally important processes.

Be sure to follow the daily posts of our Log from One Ten East at https://iioe-2.incois.gov.in and 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.

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.

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.

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.

Capt Curt Jenner AM monitors a sonobuoy for whale calls using sophisticated software. The information regarding the frequency of the sounds detected and the direction of the whale call, in relation to the sonobuoy, provides valuable insight into the migration paths of pygmy blue whales as they traverse the south-east Indian Ocean towards Indonesia. Photo: Micheline Jenner AM.

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.

A pygmy blue whale call is displayed as 5 horizontal lines in bright green at the centre of the computer screen. This colour indicates directionality, and in fact, this whale is located to the northeast of the sonobuoy. Photo: Micheline Jenner AM.

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 foremast of RV Whale Song, Curt and Micheline Jenner’s whale research ship, a pygmy blue whale is observed travelling through the Perth Canyon. This deep water canyon is an important feeding area in the south-east Indian Ocean for these pygmy blue whales, which are also seasonal travellers to the tropical waters of Indonesia during the austral winter. Photo: Tasmin Jenner.

Each individual pygmy blue whale has unique blue-grey blotch patterns, some of which are healed scars from cookie-cutter shark bites. Photo: Micheline Jenner AM.

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.

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.

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

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.

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.