Date:2/27/2012

in two submarine canyons off Moloka'i at depths ranging from 350 to 1,050 m (~1,000 to ~3,000 ft). Equipped with high-definition cameras and powerful light strobes the submersibles flew above the seafloor to quantitatively assess the presence of plant and macroalgae material and to count and identify all fish species (see Figure). This was among the first studies to quantitatively survey fish assemblages deeper than ~350 m around Hawaii, gathering more than 13 hours of video altogether. Among the most abundant species found were the so-called 'rattail' fishes (family Macrouridae) and the 'eel-like' fishes (synaphobranchids and halosaurs). Giant shark specimens were also observed but only when the submersible was stationary and not during the video transects. Therefore, that species was not included in the quantitative analysis. De Leo narrates how scary it was when he got 'faceto-face' with a 10-foot 'sixgill shark' with only the submersible's porthole separating his from the shark's nose, as the giant approached the submersible and hit the thick glass window with its face. "Wow, it was definitely a nerve-wracking sensation. I even dropped my video camera while trying to make good footage of the beast".

The researchers also report some unexpected results. They found that this 'canyon effect' of enhancing fish abundances is obliterated at intermediate depths (around 650 m) coinciding exactly with the core of an oxygen minimum zone (OMZ) that flows around the Hawaiian archipelago around those depths. An OMZ is a layer of seawater usually at subsurface that has depleted oxygen concentrations due to several biological and chemical processes, including excess respiration by microbes. This may be indicating that the bottom fish species are somewhat sensitive to the low oxygen concentrations in the water. This result corroborates previous studies that found low abundances and diversity of deep-sea scavenger animals at similar depths around Hawaii. "The expansio
'/>"/>

Contact: Marcie Grabowski mworkman@hawaii.edu 808-956-3151 University of Hawaii ‑ SOEST Source:Eurekalert

0 GOOD

Page: 1 2 3
Related biology news :

1. Calculating gene and protein connections in a Parkinsons disease model
2. Lifelong memories linked to stable nerve connections
3. Impaired brain connections traced to schizophrenia mutation
4. Brain connections for stress -- lessons from the worm
5. Calcium connections: Basic pathway for maintaining cells fuel stores
6. Brain connections break down as we age
7. Immune molecule regulates brain connections
8. Notre Dame research reveals brain network connections
9. New NOAA-funded research to illuminate connections between reefs in the Gulf of Mexico
10. Making sense of sensory connections