Finding Nemo 8: Ocean Enigmas
Finding Nemo 8
|Norfanz vessel, see full image slide show
To explore deep sea habitats and biodiversity in the Tasman Sea, a joint Australian-New Zealand research voyage carried leading Australian, New Zealand and other international scientists to uncover new marine species and habitats. The NORFANZ research voyage explored deep sea habitats around seamounts and abyssal plains around Lord Howe and Norfolk Islands through to northern New Zealand. The voyage collected biodiversity samples, DNA tissue samples, seabed habitat data, photographs and video on seamounts at depths between 200 meters and 1.2 kilometers, and surveyed free-swimming animals that live in the water masses above and around these seamounts. Australia’s National Oceans Office – the body responsible for developing and implementing Australia’s Oceans Policy – and the New Zealand Ministry of Fisheries supported the four-week voyage between 10 May and 8 June.
With cooperation from the National Oceans Office , the NASA-sponsored Astrobiology Magazine chronicles the scientific notes written by the researchers onboard. As the director of the Hayden Planetarium, Neil Tyson, wrote about the marvels of biodiversity: "I do not know whether biologists walk around every day awestruck by the diversity of life. I certainly do. On this single planet called Earth, there co-exist (among countless other life forms), algae, beetles, sponges, jellyfish, snakes, condors, and giant sequoias. Imagine these seven living organisms lined up next to each other in size-place. If you didn’t know better, you would be hard-pressed to believe that they all came from the same universe, much less the same planet".
The main goal of the summer expedition mirrored that sentiment: to provide baseline information on the, nature and potential vulnerability of these unique habitats and their biodiversity. The results will give scientists interested in biodiversity a much better understanding of the species that live on and around the deep seamounts and ridges throughout the Tasman Sea, many of which were new to science. The information will also enhance and contribute to international collaboration in oceans management.
Day21, 30 May 2003.
Low swell (<2 m), 11 knot SW wind, 16 ° C
It’s early morning and the ratcatcher is down. Last night was a mix of beam trawls and ratcatchers and one trawl with badly tangled doors. The crew efficiently untangled the knot and trawling continued. One catch brought in many redbait (Emmelichthys nitidis), a small fish in the bonnetmouth family (Emmelichthyidae). The bonnet name refers to their expandable jaws. These fish feed in large schools like anchovies.
|Pteropod Shells, see full image slide show
Everybody is working very hard. It is 12 hour shifts, seven days a week. The crew work from 12 to 12 and have all the work associated with running and maintaining the ship, deploying nets and changing between sampling gear types. They also have nets to prepare, gear repairs and modifications. The researchers work from 3am to 3pm (or vice versa). There is always a lot to do: making sure that all specimens are identified correctly, collection data is logged, animals are preserved in the right manner, computers are functioning properly, photo reference folders are kept up to date, tissue samples are taken, alcohol and formalin supplies are maintained, full drums of specimens are correctly stowed or backlogs of specimens are not left for the next shift. For some researchers, they are the only expert in their group so they also try to help out the alternate shifts. Bed is a very welcome location at the end of each shift and a long steam between sites is always a welcome catch-up.
Included in one of yesterday’s trawls was another toothy deep-sea fish, a Scaleless Dragonfish (Opostomias micripnus ). Another trawl contained a chimaera egg case, complete with developing baby chimaera.
Cartilaginous fishes (sharks, rays and chimaeras) have three different ways of having their young. The first is by laying eggs (known as "ovipary"). Chimaeras (all 3 families), skates (family Rajidae), catsharks (family Scyliorhinidae) and bullhead sharks (family Heterodontidae) all lay horny (keratin) egg cases. These sometimes wash up on shore and get called "mermaid’s purses". The eggs are laid on the seafloor and are left for the young to develop on their own (taking 3 to 9 months). Different shape egg cases are laid in different places, the spiral cases of bullhead sharks (like the Port Jackson Shark) are wedged into crevices, those of catsharks have long threads and are tangled around algae or corals, while the flat egg cases of skates and chimaeras probably lie on the seafloor or are posted" into crevices.
The second sort of reproduction is used by stingrays and most sharks. It is called "ovovivipary", which means "egg-laying and live-bearing". This means that there is an egg enclosed in a membrane that develops and hatches inside the oviducts of the female, so that the young are free-swimming when they hatch. This is a good strategy compared to egg cases in that the young start life well developed and can immediately fend for themselves.
The third strategy is true live bearing of young (known as "vivipary"), where direct internal development occurs. Only one group of sharks uses this strategy: members of the family Lamnidae that includes the Mako, Porbeagle and White Pointer sharks. Very weird behaviour occurs in some (or possibly all) of these sorts of sharks. The young start to eat each other, while still inside the mother! This is called uterine cannibalism". The developing shark pups first grow off their own yolk sac. They then develop functional mouths and stomachs. The strongest pup starts by eating unfertilised eggs that are also in the ovary and oviduct. Once they’ve run out, it starts to eat its brothers and sisters! In the end only one very strong pup survives, coming out into the world snapping. There is a story of an ichthyologist (the official name for a fish expert) opening the belly of a dead female Porbeagle shark to be attacked and bitten by the ferocious pup inside.
|Lizard Fish, see full image slide show
In general sharks and rays produce few young. Some sharks and rays produce only one pup at a time. The record is held by one whale shark from Japan that had 302 pups inside it. This is not many compared with some fish species that can produce millions of eggs.
A number of the attributes of sharks, rays and chimaeras make them vulnerable to overfishing: they produce few young, gestation can be up to 2 years, they are slow growing (some don’t mature until 12 years old) and the largest produce the most young (and are often the first to go in a fishery). Many shark species have shown rapid declines from overfishing. This includes many deep-sea shark species around the world. Shark research on the NORFANZ cruise provides critical information on identification, diversity and distributions of sharks and rays in this region, important information for appropriate management and protection of these animals.
We’ve just brought up a "pipe dredge", a steel tube on a chain used to sample seafloor sediment. It came up packed with fine white sand and Penny and Don are now sieving it to see what small animals it contains.
We have had a lone Wandering Albatross behind the ship all day, along with Cape Petrels (a bird more typical of subantarctic waters) and Short-tail Shearwaters.
Day 22, 31 May 2003.
Low swell (2 m), 16 knot S wind, 18 ° C
It’s 10.30 am and we’re currently headed towards Reinga Bank. It’s about 10 hours steaming so we’re using the time to catch up on everything. We’ve had a very good run with suitable seafloor for sampling and had very few gear problems, compared with the difficulties of very rocky ground in the first leg of the cruise. We are returning to rockier ground now, so will be relying heavily on the seabed mapping team for choice of locations.
The list of new species and new distributional records are getting very impressive. So far the voyage has collected samples and records of more than 500 fish species and over 1100 invertebrate species. The diversity in forms and adaptations is fantastic. Researchers onboard are starting to tally the total number of new discoveries. Many of the new distributional records are for species that have rarely been sampled. Last night’s trawls provide a good example.
|Long nose chimera, see full image slide show
A ratcatcher trawl around midnight brought up a large number of slimy slickheads (Rouleina attrita) and a total of 14 rattail species in a single catch. According to the identification literature on board, at least one and possibly two of these species are new to science. The catch included another slickhead species, a Norman’s Snothead (Mirognathus normani), which seems particularly appropriate as I have the cold that is currently roaming the ship. The most exciting find in this haul, one that sent Andrew Stewart of Te Papa into convulsions, was a very rare anglerfish known as a Mossfish.
At 4 am this morning we did the last ratcatcher trawl for the Wanganella Bank. It sampled at 900 m and mainly caught small sharks. It also closed the book on the long saga of the "Enigma Skate".
Twenty years ago, the original "Tangaroa" (since replaced by this ship) captured a strange small ray on the Wanganella Bank. It was a single female specimen of skate (sting-less rays) that was so different it was even unclear what group (genus) it belonged in. Adult male specimens are critical in identifying and describing sharks and rays. The male reproductive organs (especially the "claspers") are one of the best diagnostic characters. At the time, Dr Peter Last, a shark and ray expert from CSIRO Marine Research, began the formal description necessary to name this distinctive skate, but a male was needed.
The problem is that the deep water in this corner of the planet is a long way from anywhere. Not many people poke around out here. The few commercial fishing boats that have fished out here are not particularly interested in little rays. No specimens surfaced in 20 long years. One of the tasks of the NORFANZ cruise was to return to the same location and see if the new "Tangaroa" could find better voucher specimens.
For the last two days we’ve been trawling in this region. It has been a fascinating area and has brought up many interesting animals. There was initial excitement as several female specimens of the "Enigma Skate" were caught. More excitement followed as two immature males came in. By the last trawl for the region last night, Peter still didn’t have his adult male. So a nervous group stood around the opening net at 4 am last night, waiting to see if an adult male would turn up. The catch contained some small sharks, a larger more familiar skate and a mix of rattails. Then suddenly there was a shout and a small skate was extracted from the pile. Peter confirmed it was an adult male. An adult female followed. The "Enigma Skate" could finally be named.
Taxonomy is the study of identifying and naming plants and animals (living or dead). It is not just stamp collecting (no slight intended against stamp collectors). Formal description of any species is important for a number of reasons. It is a universally agreed system for comparisons with other named and new species. It allows:
development of identification tools
* generation of lists of fauna and flora for specific regions
* investigation of relationships between creatures, i.e. the study of food webs
* generation of information on biodiversity, rarity and conservation status
* investigation of the evolution of life on earth (and in the sea).
* Sound taxonomy underpins all other branches of biological and conservation research. Without it, the rest are meaningless.
It’s 2 pm now and we’ve stopped to do a sound velocity probe, allowing the seabed mappers to calibrate their equipment as they constantly map the seafloor beneath us. Back to sampling tonight.
Day 23, 1 June 2003.
Low swell (1-2 m), 10 knot S wind, 17 ° C
Well, we are on a seamount on the Reinga Bank and, as expected, it is a hard spiky rocky seafloor, not very net friendly. In these situations we revert to the old indestructible Sherman sled. It has been down twice overnight along with a single orange roughy trawl.
|Sea Spider, nearly a foot across, see full image slide show
Sherman didn’t catch much on the first run but it certainly earned its keep on the second, bringing up a high diversity of small invertebrate species. After spending most of the night working up this catch, the night invertebrate team identified 96 species of invertebrates, of which more than 40 species were first records for the voyage. So it was a very busy night of careful sorting (with fine tweezers), looking up identification keys, and documenting and photographing all the new material. The seafloor on the top of this rocky seamount is made up of rock and rubble beds, supporting a rich invertebrate fauna. Seamounts can often support much richer communities than the surrounding deep-sea slopes and plains. This is caused by the nature of water flow over seamounts. As currents move across the seafloor and bump into a seamount, eddies and currents form that can concentrate nutrients and draw them up towards the surface. This is sometimes called a "Taylor’s Column". This mixing of cooler, nutrient-rich water with slightly warmer shallower layers is very productive and can support rich marine life. Once you add rocky surfaces for invertebrates to attach to, these environments can end up supporting large animal communities. Sherman appears to have sampled one of these last night.
People usually associate corals with shallow tropical waters, but the deep sea is also home to many types of corals. Shallow water corals (like those found on the Great Barrier Reef ) get most of their food from sunlight by nurturing small plant cells (called zooxanthellae) within their tissues. The plant cells produce sugars by photosynthesis in return for a safe place to live. Around 95% of a shallow-water corals food comes from these plant cells. In the deep sea it is different. There is not the sunlight so there is no way to gain nutrients from symbiotic plant cells. Deep-sea corals must use their stinging tentacles to catch small animals or feed on the rain of fine organic matter that filters down from the surface. Perhaps due to the low food levels in the deep sea, many corals are very long-lived.
|Tongue Sole, see full image slide show
The rocky seafloor at the Reinga Bank site last night seemed ideal for corals and many different types were found. These included species of black coral, several bamboo corals (named for the regular dark bands along the coral stem that make them look like bamboo), octocorals (named after the eight tentacles on each polyp), fan corals (also known as "gorgonians") and a few solitary corals. There were also pieces of coral rubble from several hard coral colonies ("scleractinians"), showing that these coral types also occur in the area. In turn, the corals are home to many free-living invertebrates. The crustaceans in last night’s catch included many new species of squat lobster, small crabs, shrimps and hermit crabs. One rare find was four animals of a sponge-dwelling shrimp in the family Spongicolidae. This deep-water family of shrimps is very poorly known. It is a rare event to get a single specimen, let alone four. Other groups included snails, serpent stars, slate urchins and sea stars. Coral colonies can also support anchored invertebrates (known as sessile" animals), such as stalked barnacles.
But by far the most common species in this catch was a new species of brittle star (Ophiacantha sp.) that came up in its thousands. We ended up with three fish bins of these tiny stars. The densities of this species are obviously very high.
An orange roughy trawl has just come up from around 1000 m deep. It mainly contained very slimy slickheads, as well as several species of chimaera, rattail and basketwork eels. There was also a single snipe eel and a viperfish. Meanwhile, the Sherman has come up with a pile of rocks and about three squashed prawns. It has just gone out again.
Lots of birds behind the ship today, mainly Cape Petrels and shearwaters but also a Wandering Albatross and what look like two Grey-headed Albatrosses.
|Spook fish, underside see full image slide show
The Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the New Zealand National Institute of Water and Atmospheric Research Ltd (NIWA) are providing scientific support for the voyage. The NORFANZ voyage will use NIWA deep-sea research vessel, the R.V. Tangaroa (NORFANZ).
The expedition received considerable interest from scientists worldwide. Twenty four scientists from more than eleven research organisations will be represented onboard, including staff of CSIRO, Hobart; Museum Victoria; the University of Tasmania; Australian Museum; Queensland Museum; Northern Territory Museum; NSW State Fisheries; Te Papa, Wellington; National Institute of Water and Atmospheric Research, New Zealand; Institute de Recherche pour le Développement, Noumea; Natural History Museum, Paris; and California Academy of Sciences, San Francisco.