Diving Expedition to a Methuselah of the Sea

Coelacanths have been in existence now for more than 400 million years. Scientists have investigated the way of life of this ancient, nocturnal fish

Tauchfahrt zu einem Methusalem der Meere

Der Quastenflosser existierte bereits vor 400 Millionen Jahren. Forscher haben die Lebensweise dieses archaischen, nachtaktiven Fisches untersucht

Manned submersible „JAGO“

The manned submersible „JAGO“ is a human occupied underwater vehicle (HOV) designed for personal exploration and research in all types of aquatic systems and habitats. The seafloor along the continental shelf and slopes within the ocean twilight zone is JAGO’s main target area. The DNV-GL classed 2-person submersible has a maximum operating depth of 400 m. The two occupants, the pilot and one observer, are seated at 1 Atmosphere in a steel pressure hull with two large acrylic windows. The submersible’s small size and lightweight construction (3 T) allows worldwide operations from on board a wide variety of vessels as well as transport in a single standard 20-foot container together with all support equipment. Typical applications include personal observation of the sea bed and water column, video and photo documentation, selective non-intrusive sampling, placement of sensors and experiments, underwater inspection, as well as location and recovery of object

1. Wochenbericht FS Alkor Reise AL533

JAGO-AUV-FieldTrials, Äolische Insel

2. Wochenbericht FS Alkor Reise AL533

JAGO-AUV-FieldTrials, Äolische Inseln Wochenbericht 05.-18.02.202

Coelacanth population, conservation and fishery activity at Grande Comore, West Indian Ocean

The only known population of coelacanths, in the Comores, western Indian Ocean, is endangered by human predation. Historical catch data from Grande Comore reveal that annual catch rates increased steadily from 1954 until the 1970s. This trend was temporarily interrupted due to an international policy introducing motorized boats and promoting offshore fishing techniques. Coelacanths are only caught from traditional unmotorized outrigger canoes as an incidental by-catch of deep water line fishing. A complete survey of all motorized and unmotorized vessels in 1995 at Grande Comore in comparison to earlier years indicated that a recent decreased use of motors and increase of unmotorized canoe fishing has led to an increase in coelacanth catches. Conservation measures and strategies for reducing the fishing pressure exerted on coelacanths are discussed. The southwest coast of Grande Comore should be designated as a nature reserve and protected area where immediate protection measures should be taken, an opinion which is supported by Comorian authorities

Archangelopsis jagoa, a new species of benthic siphonophore (Physonectae, Rhodaliidae) collected by submersible in the Red Sea

A new species of rhodaliid siphonophore, Archangelopsis jagoa sp, nov., is described from three specimens collected at depths between 250 and 370 m in the Gulf of Akaba, Red Sea, by the submersible JAGO. Comparisons are made with the established species of that genus and observations, both in situ and on the living animals in captivity, are reported

RV ALKOR Fahrtbericht / Cruise Report AL533 - Mutual Field Trials of the Manned Submersible JAGO and the Hover-AUVs ANTON and LUISE off the Aeolian Islands, Mediterranean Sea, Catania (Italy) – La Seyne-sur-mer (France) 05.02. – 18.02.2020

The tight program of scientific research cruises usually does not leave enough time for thorough tests of new research equipment and their system components, nor for extensive pilot and handling training. For this reason, ship time was requested for sea trials of two types of autonomous (not tethered) underwater vehicles owned by GEOMAR, the manned 400-meter submersible JAGO and the Hover-AUVs ANTON and LUISE, type Girona500. The aim was to test several technical and operational aspects with both vehicles at locations with differently structured terrain (from flat ground to steep rocky slopes) and to water depths of up to 500 meters. The Aeolian Islands in the Tyrrhenian Sea north of Sicily were chosen as test area. The volcanic islands offer sheltered sea conditions at their leeway, and bottom currents are usually weak or absent. Rocky and steep slopes are located in short distances to areas with flat underwater topography, providing ideal test conditions

Fishes of the deep demersal habitat at Ngazidja (Grand Comoro) Island, Western Indian Ocean

Underwater observations of the coelacanth, Latimeria chalumnae</I> Smith, 1939, from a research submersible provided opportunities to study the deep demersal fish fauna at the Comoro Islands. The demersal habitat in depths of 150-400 m at the volcanic island of Ngazidja is low in fish diversity and biomass, compared with the shallow-water coral reef habitat of Ngazidja or the deep demersal habitats of other localities in the Indo-Pacific region. The resident deep demersal fish fauna at Ngazidja is dominated by the coelacanth, an ancient predator that is specially adapted for this low-energy environment. Other large fish predators are scarce in this environment, because of the heavy fishing pressure from local fishermen. Eighty-nine fish taxa (including 65 recognizable species) were recorded from videotapes, photographs, visual observations, fishermen's catches and ancillary attempts to sample the fish fauna with baited fish traps, gill nets, and hook and line. Although no coelacanth feeding events were seen, seven fish species are known from coelacanth stomach contents, and 64 other fish species in this habitat are considered potential prey of this dominant predator

Water mass characteristics and sill dynamics in a subpolar cold-water coral reef setting at Stjernsund, northern Norway

The Stjernsund, located in subpolar setting at 70.5°N off northern Norway, hosts a thriving cold-water coral reef community on a morainic sill. Dives with manned submersible JAGO identified the different reef zones and sedimentary facies on top and on the slopes of the sill. Hydrographic investigations indicate different water mass distribution east and west of the sill. Winter Mode Water and Norwegian Coastal Water variability depends on the runoff and freshwater discharge into the fjord. Atlantic Water dynamics are almost entirely tidally driven. High-resolution CTD time series covering a full tidal cycle demonstrate mixing processes occurring east of the sill. Additionally, the different bathymetric distribution of living corals on the western and eastern slope of the sill portrays the dependence on these tidal dynamics. The living corals thrive just below the isopycnal of 27.5 kg m−3, which marks the boundary between Norwegian Coastal Water and Atlantic Water