Knowledge Of Ross Sea Marine Biodiversity And Ecosystems Expands
12 March 2004
Interview and photo opportunity: 11am, Saturday 13 March, Wellington
The Antarctic marine research project, Ross Sea 2004, which concludes tomorrow, has greatly increased scientists' knowledge and understanding of the Ross Sea ecosystem.
The 50 day research and seabed mapping project was funded by the Ministry of Fisheries (MFish) and Land Information New Zealand (LINZ), in cooperation with the Italian Antarctic Research Programme. MFish funded the marine research component through the New Zealand Biodiversity Strategy research programme "BioRoss", contracting National Institute of Water & Atmospheric Research Ltd (NIWA) scientists to carry it out. LINZ funded the hydrographic survey component of the voyage for the maintenance of nautical charting.
Ross Sea 2004 Project Leader Jacqui Burgess (MFish) said the voyage, from January to March 2004, ends on Saturday, when the NIWA Research Vessel Tangaroa returns to Wellington.
"The research carried out in the Ross Sea and around the Balleny Islands makes an enormous contribution to our understanding of the marine ecosystems and their biodiversity in these locations," she said.
"As the results are analysed I am sure that we will learn a great deal of new information about the animals and plants that live in Antarctic waters, and how their existence is impacted by the extreme environment."
Ms Burgess said other successes of the voyage included:
- Indications that two invertebrate species new to the Western Ross Sea area and maybe also to the Antarctic have been found. They are:
New detailed hydrographic survey information which will provide more accurate navigation charts of major shipping lanes in the Western Ross Sea. Survey work focused on the shipping lane running from Cape Hallett to the Possession Islands to Cape Adare, plus the inshore areas around the Ridley Beach Antarctic Specially Protected Area (ASPA), Cape Adare, which was surveyed using single beam and multibeam echosounder systems and side-scanning sonar.
A large amount of sampling was achieved, despite adverse weather conditions. The BioRoss team sampled three transects in the Western Ross Sea to quantify levels of biodiversity, using a grab, sled and trawl gear, catching a large variety of animals.
The deep and shallow water multibeam maps of the seabed topography will also enable characterisation of seabed bottom sediment type, of the locality and extent of iceberg scours and how these seabed features influence the distribution and diversity of the animals and plants sampled.
Contributed to the international effort to understanding oceanic circulation by deploying some Argo floats/buoys from 'Tangaroa'. These Argo floats/buoys remain in the sea for several years and transmit data to scientists via satelite.
- A red striped Amphipod, genus Epimeria
- A small sea slug (nudibranch), belonging to the genus Doto. As far as it was known, this genus was recorded in Antarctica once before in the 1920s, when it was found close to the French base Dumont d'Urville, but the particular species (representing this genus) was never described. This specimen will allow a formal description of the species, and will be another small but important contribution to our knowledge of the Antarctic fauna
Ross Sea 2004 aimed to improve understanding and knowledge of the biodiversity and ecology of the Ross Sea, and the ability to effectively manage human activities in the region. Two research vessels were used for the project - the NIWA Research Vessel Tangaroa, and the Italian Research Vessel Italica, which worked between Terra Nova Bay and Cape Adare.
A website was set up for the voyage, online at www.rosssea2004.govt.nz, with a daily diary written by MFish representative Susie Iball.
The high resolution photographs taken on the voyage and shown on this website can be reproduced provided they carry the attribution: "Reproduced by kind permission of the Ministry of Fisheries."
Interview and photo opportunity
There will be an opportunity for media to interview MFish representative Susie Iball and other key members of the voyage team when the RV Tangaroa returns to Wellington.
Time and date: 11am, Saturday 13 March
Place: On board the NIWA Research Vessel Tangaroa, at Aotea Wharf, Wellington (this is the main Center Port wharf next to the one used by the Inter-Island ferries).
For further information please contact
Jacqui Burgess, Science Manager, Biodiversity, Ministry of Fisheries, Tel 494 8256
Some of the marine life encountered during the Ross Sea 2004 Voyage.
High resolution photographs of these species can be found on the "Discoveries" section of the website www.rosssea2004.govt.nz. These photographs can be reproduced provided they carry the attribution: "Reproduced by kind permission of the Ministry of Fisheries."
Icefish such as this one have some intriguing means of transporting oxygen around their bodies. Haemoglobin and red blood cells are the normal components which transport oxygen around the body of vertebrates like humans and most fish. Icefish are interesting physiologically because they are the only group of vertebrates that possess neither the pigment haemoglobin nor functional erythrocytes (red cells) in their blood. Consequently the blood of these fish is colourless and their gills are white, instead of being red like all other fish. Hence their alternative name of 'white blooded fish'.
As well, icefish have a much larger blood volume than 'red blooded' fish and, in order to pump the extra blood around the body, a much larger heart. So, whereas red-blooded fish have a low volume and relatively high blood pressure system, icefish have a high volume, low pressure blood system with associated larger arteries/ vessels. The icefishes' specialised features mean that they can only remain active under conditions where there is plenty of dissolved oxygen in the seawater.
Only four species of penguins actually breed on the Antarctic continent proper, and the Adélie penguin is one of these. Adélies are a small to medium-sized penguin (approx. 70cm high) and are found all around Antarctica. Like all penguins, Adélies must come ashore each summer to reproduce. Breeding colonies or rookeries are found on ocean-accessible beaches and scree slopes on ice-free, rocky islands and peninsulas. Rookeries are usually made up of thousands of birds. Adélies return to their rookery areas between September and October each year. Egg laying takes place from October to November, and possibly even in early December. Adélie parents construct shallow nests of rounded pebbles and lay between one and three eggs. Taking it in turn to incubate them. After hatching, the chicks are brooded in the nest for about three weeks, then leave the nest and form into 'creches' in which they wait for their parents to return from their foraging trips. Chicks are fed by their parents approximately every 1-2 days. The chicks will leave the rookery in late January and February when they're about two months old. Once they leave the colony they become independent of their parents.
Antarctic fish names
In most parts of the world, when you catch a fish there is invariably someone around who can tell you its common name or something else about some aspect of its biology. Not so in the Southern Ocean. There is no native human population who would have caught these fish, let alone thought about giving them common names. With the exception of those species like the toothfish and icefish which are currently fished commercially, this is a region where most fish have only their scientific Latin names. Names are generally given because they identify particular attributes of the species in question. However when the particular attributes are used to identify other similar species another naming method must be used. A common practice is to use the names of geographical regions or famous people. The lack of information on the distribution of many Antarctic species means that realistically there are few options to name them after geographical areas, and so famous peoples' names have often been used instead.
Plants need sunlight to be able to grow. This means that Antarctica can be a difficult place for a plant because it is dark for half of the year. It is even more difficult for plants that grow underwater than those that grow on land. In summer, when it is daylight for 24 hours, the sea can still be covered in ice. The ice cover stops a lot of light from getting through to the water below.
In general, the further south one goes, the longer the period of winter darkness and the longer the time during the year that the sea stays covered in ice. This means that seaweeds (macroalgae) in the ocean must be specially adapted to not only grow in very cold water (-1.98o C) but also to grow where there is very low light. At Cape Evans, which is on Ross Island (near Scott Base and McMurdo Station), and at a latitude of more than 77o S only three types of macroalgae can grow under these extreme conditions. They are all red algae, which are efficient at using very low light. Despite adaptations enabling them to grow at this latitude, growth is slow and they only reach a relatively small size. At Cape Hallett latitude 72o S, further north than Ross Island it was expected that there would be more types of macroalgae and that is what was found. This observation is in keeping with the knowledge that there is more light available at this lower latitude and the environment is comparitively less harsh than higher latitudes.
Amphipods are crustaceans, and crustaceans are a large, primarily aquatic group. Crustaceans include familiar animals such as crabs, shrimp, crayfish and lice.Crustaceans are the most abundant group amongst the Antarctic bottom-living invertebrates (benthos). Of all the orders of crustacean, amphipods are the most dominant, with over 800 species so far described from the Southern Ocean. Larger crustaceans like crabs (Order Decapoda) are not so common in these waters. Some very interesting specimens have been caught on this voyage, for example one with red stripes (which was nick-named 'zebra'), may be a species which has not yet been described.
Sea Spiders and Leeches
Sea spiders (pycnogonids), sometimes called whip scorpions, are exclusively marine, and mostly bottom dwelling invertebrates. They feed using a well developed proboscis to "suck" up the juices of other soft-bodied invertebrates like soft corals or dead jelly fish. Sea spiders represent one of the few examples of "fast moving" invertebrates in Antarctic waters. They are always patrolling the sea bottom in search of food.
Sea spiders are distributed worldwide, but in temperate-tropical waters they're generally scarce, and rarely exceed 1cm in diameter, even when adult. It's quite the opposite story in Antarctica! Here they are at their most diverse, and there are many "giant" sea spider species. Members of the genus Colossendeis for example, can have leg spans up to 50cm wide, and bodies as long as 5cm, or more.
Many sea spider specimens are found with stalked barnacles attached to their bodies. We have collected examples of these associations several times during our "Tangaroa" cruise. But these are not the only guests which sea spiders host.
Sea spiders are also used as a means of transport by Marine leeches! Marine leeches (Hirudinea) belong to the Phylum Annelida, together with the oligochaetes (the earth worms) and polychaetes (the "marine" worms). Marine leeches are blood-suckers, just like the more familiar freshwater leech Hirudo medicinalis, which is very common in unpolluted European rivers. However, unlike their European relatives, marine leeches have never been used for medical purposes.
Leeches are capable of strong muscular contractions which enable them to swim for short distances in search of suitable hosts from which to suck blood. This kind of swimming consumes a lot of energy, and so in colder Antarctic waters, leeches have found a good way to bypass this problem! They in fact use Sea spiders like "marine buses", riding along on them in search of a "good" fish. While attached to sea spiders, leeches "whip" the water with a continuous head movement to try to detect the presence of any fish nearby. When they detect a fish, they leave the sea spider almost immediately and attempt to attach to the fish as soon as they can. We can see two different groupings of leeches according to the blood colour of their host. The opaque white group feeds on the transparent blood of the icefish, and the other group, which is reddish in colour, feeds on fish with normal red blood.
Brittle stars, sometimes known as basket or serpent stars (Subclass Ophiuroidea), are echinoderms. They are therefore closely related to sea stars, sea urchins, sea cucumbers and crinoids, all of which are found in Antarctic waters. They are ornately patterned and range in shade from orange to red to brown. They typically have five long, snake-like arms which radiate from a central disc. These arms may be tightly curled, and are easily dislodged - hence their common name of 'brittle star'.At virtually all of the BioRoss stations sampled on this voyage brittle stars have been encountered. Despite their small size (disc diameter of 3 -10 mm), they play an important role in the benthic community. They generally feed on organic matter that has drifted down through the water column and settled on the seabed. However, some of the larger species of this group have adapted to stalking live prey.
One unique characteristic of Antarctic brittle stars is that about 50% of the approximately forty species described are brooders - which means that they shelter their young. In contrast, only 15% of New Zealand brittle star species exhibit this trait.
This was the most abundant group of animals have encountered in sled and trawl samples and are more closely related to humans than any of the other invertebrate groups such as sea spiders, worms, leeches, bivalves and amphipods.
Ascidians, or, sea squirts, belong to a primitive group of "chordate: animals - that is, animals bearing a backbone. However, it is only the tadpole larva, not the adult, which exhibits the very early form of a spinal nerve chord.
Because ascidians are so abundant, they are immensely important members of the benthic ecosystems in the Ross Sea, forming a three-dimensional structure which provides many other species with a habitat. Such animals might not otherwise be able to live on a flat, muddy or sandy seafloor. Thus, biological diversity may be enhanced within dense ascidian aggregations. Ascidians are sessile filter-feeders which are especially common in shallow waters, but are also found in the deep sea. They attach directly to the sediment surface, to rocks and pebbles, or sometimes to other animals such as hydroids and stone corals. They resemble a bag with either two openings called siphons (solitary ascidians), or many openings - colonial ascidians. Water is sucked in through one siphon and expelled through the other. In between the two siphons the water is filtered and the food particles are removed to be "eaten".
Lollypop sponges consist of a stalk with a ball-shaped body on top. They can grow up to 20 cm long, and 2.5 cm in diameter. This is a bipolar species, and it is found throughout Antarctica, from 60 to 600 m deep. Like most Antarctic animals, lollypop sponges are very slow growing. In the Weddell Sea, they have been estimated at up to 151 years old.
Sponges are made of living material and dead spicules. Spicules (similar to a needle made of glass) give the sponge structure and provide some degree of protection against predators. When the sponge dies, the spicules fall to the seafloor and form 'mats', which can be up to 1.5 m thick.
As icebergs drift around the sea, they can scrape along the seafloor, scouring the bottom and wiping out the seafloor community. Lollypop sponges are important in recovery of these areas after iceberg scour. They are amongst the first sponges to re-grow there, and help make the seafloor a more attractive place for other animals to live by providing the first spicules to form spicule mats. Perhaps more importantly, they also provide the first living quarters above the seafloor for other animals to settle on. Quite large anemones have been found growing on their stalks.