FS Sonne Fahrtbericht / Cruise Report SO 209, Bioluminescence and biological rhythms in the mesopelagic fauna, Guayaquil (Ecuador) - Coquimbo / Valparaiso (Chile), 30.08.- 17./21.09.2010 (English)

2010
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The main purpose of the cruise was to study the sensory mechanisms of bioluminescence in the mesopelagic fauna. Furthermore, the presence of endogenous diel oscillators was investigated as a possible control mechanism for the daily vertical migrations of midwater animals. We conducted 20 trawls between 1,700 and 100 m depth and collected eyes and brains of mesopelagic fish for immediate experimentation on board or fixation and subsequent investigation in the home laboratories. Another major project involved the study of hadal faunal communities. Five deployments of University of Aberdeen Oceanlab autonomous landers were carried out at depths of 4,602m (control), 5,329m, 6,167m, 7,050m and 8,063m. The lander was equipped with baited traps and took time-lapse videos over a period of 12-20h after which they were recovered. Various families of fish, amphipods and snails were observed down to depth of 7,000, with abundance and number of species decreasing with depth. At 7,000m, only snailfish (liparids) came to the bait. From the video footage it would appear that liparids in the Peru-Chile Trench belong to a yet undescribed, endemic species. This confirms the hypothesis that each trench system around the Pacific Ocean is home to its own, endemic species of liparid snailfishes. The collection of amphipods and snails serves to perform population genetic studies, taxonomy and define the zonation of scavenging amphipods through the trench depths. The other, novel, instrument first deployed during this cruise is a floating platform, called Medusa, developed by J. Marshall and L. Frey for the University of Queensland, Brisbane. Medusa is also equipped with a baited camera and has spent up to 24h suspended at depths between 1,000 and 500m during four deployments. Sightings included three large Humboldt squids and numerous gelatinous and crustacean midwater fauna. The investigation of the visual systems of deep-sea fauna was focussed on teleost fishes and cephalopods. Similar approaches were used in both cases: Molecular and spectral analysis of visual pigments and the enzymes of the transduction cascade. Histological and immunocytochemical study of the morphology, including identification of neuron type diversity, and specific labelling in order to establish intraretinal and retino-tectal connectivity and synaptology. While the groups of S.Collin, J. Partridge and H.-J. Wagner concentrated mostly on visual specialists like pearleyes or lanternfishes, S.Collin also started a project to study non-visual fish such as melamphaeids of anglerfish. This will potentially identify the barely essential neural elements, a simple visual system needs to operate. It is the first time that such a wide array of different methods are applied as an integrative approach for the investigation of a sensory system in deep-sea fish The molecular mechanisms of endogenous rhythms in mesopelagic fish were also further studied. After identifying and characterising two of the clock gene family, namely per and cry from material of the last cruise we have now conducted culture experiments for 36 hours in order to monitor potential cyclic changes in the activity of these genes (H.-J. Wagner). Multibeam mapping of the ocean floor was performed routinely when entering Peruvian waters. This work is part of an ongoing project to map the topography of the ocean floor in as great detail as possible in order to better understand the processes related to the subduction zone in the Peru-Chile trench. The observations will be of use to future geophysical, geological and geochemical investigations.

  • Title:
    FS Sonne Fahrtbericht / Cruise Report SO 209, Bioluminescence and biological rhythms in the mesopelagic fauna, Guayaquil (Ecuador) - Coquimbo / Valparaiso (Chile), 30.08.- 17./21.09.2010
  • Author / Creator:
  • Publisher:
    Anatomisches Institut, Universität Tübingen
  • Place of publication:
    Tübingen
  • Year of publication:
    2010
  • Size:
    75 pages
  • DOI:
  • Type of media:
    Report
  • Type of material:
    Electronic Resource
  • Language:
    English
  • Classification:
    DDC:    550 Earth sciences and geology
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