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 […]
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 […]
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.
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.
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!
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.
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 […]
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 […]
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 […]
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.