Fish Habitat Science
It’s well known that
shipwrecks, drilling platforms and other man-made objects in relatively
shallow water (less than 100m, or about 328 feet) often create small oases
of marine life, attracting a wide variety of fish and other creatures. This
effect is most dramatic in areas where the seabed is flat and sandy, and
offers few notable features. Relatively little, however, is known about how
man-made objects effect the local marine environment in the deep sea, far
below the level where light from above can penetrate.
This phase of the Deep Wrecks
Project is under the overall direction of Dr. William F. Patterson, III of
the University of Alabama. Dr. Patterson will look at three main areas: (1)
fish community structure, (2) the age and growth patterns of fish, and (3)
the diet and trophic structure of the fish population.
To study the fish community
structure around each of the wreck sites – that is, types and number of fish
present -- Dr. Patterson and his team will set out several specialized fish
traps designed to collect reef fish of different sizes. Using the Triton XL
ROV, the team will also “fly” a regular pattern of transects across the
wreck and the nearby seabed, recording video that will later be analyzed to
document and identify fish in the area. Individual fish collected from the
traps will be identified to species and will be used to help identify fishes
observed in videos.
To study the age and growth patterns
of the fish around each of the wrecks, Dr. Patterson and his team will
extract sagittal otoliths from individual fish caught in fish traps.
Otoliths, also known as “earstones,” are calcareous concretions that serve
as part of the hearing and balance system in fish. These otoliths will be
examined in the laboratory using a special imaging system that will allow
the researchers to estimate the age of each individual fish collected. These
ages will then be compared to estimates of size and age at various natural,
hard-bottom sites in deep water.
Dr. Patterson and his team will
study the trophic structure – that is, the food web – of each site by
analyzing the stomach contents of the fish caught in the traps. Stomach
contents will be identified to lowest taxonomic level possible and then
dried. Stable isotope analyses will be performed on tissue lateral muscle
tissue samples from the most abundant fish types present. These samples will
be analyzed with an isotope ratio mass spectrometer at the University of
Mississippi’s field station in Bay Springs, Mississippi.
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