Home | Contact ST  
Follow ST

Marine Resources


October 2013 Issue

Some Humpback Whales Found to Stay in Antarctic All Winter
Biologists and physicists from the Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research found out that not all of the Southern Hemisphere humpback whales (Megaptera novaeangliae) migrate toward the equator at the end of the Antarctic summer. Part of the population remains in Antarctic waters throughout the entire winter, the scientists reported in PLOS ONE. This discovery is based on underwater recordings from the PerenniAL Acoustic Observatory in the Antarctic Ocean (PALAOA).

In 2008, the humpback whales were present near the observatory with the exception of the months May, September and October. In the following year, they were absent only in September. Therefore, it is highly likely that humpback whales spent the entire winter in the eastern Weddell Sea during both years.

The scientists now want to find out to which population the humpback whales from the eastern Weddell Sea belong. They are planning to compare calls from the PALAOA recordings with humpback whale song from the coastal waters off Gabon and Mozambique. Each humpback whale population has its own song. Songs therefore provide an acoustic fingerprint, on the basis of which scientists will hopefully be able to say where the animals that spend their winters off the Antarctic continent breed.

The live broadcast of PALAOA recordings in the Antarctic sea are available at http://bit.ly/xPBFVE.

Foundation Set for Oyster Reefs in Gulf of Mexico
Researchers from the Department of Life Sciences at Texas A&M University-Corpus Christi and the Harte Research Institute for Gulf of Mexico Studies placed thousands of pounds of crushed concrete, rock and oyster shells in Aransas Bay and Copano Bay in hopes that oysters will make their homes there.

They put down the building blocks that small larvae oysters need to create new generations of oysters. Using barges, they worked to expand the current oyster reef in Aransas Bay adjacent to Goose Island State Park and in Copano Bay with oyster shells collected from local restaurants.

The oyster reefs were built as 12 mounds of complex habitat, 12 inches high, and 20 to 30 yards long, and in a manner that creates a habitat that sportfish can swim around.

While only about 15 percent of the world's oysters reefs remain, the Gulf of Mexico waters are in better shape than many areas when it comes to oyster populations. This is good news for the state of Texas, where oysters are big business. Aside from their purpose as a food resource, oysters also provide a lot of benefits to coastal ecosystems. As they eat, they filter pollutants, waste, heavy metals and things that can degrade water quality. This helps to create cleaner, clearer bay waters.

Oyster reefs also provide habitat for small fish and crustaceans, which are prey for larger sportfish.

This project is funded by the Coastal Conservation Association, Gulf of Mexico Foundation, National Fish & Wildlife Foundation and NOAA.

Deep-Sea Squid Attracts Prey By Appearing Smaller
Researchers associated with the Monterey Bay Aquarium Research Institute (MBARI) conducted a study on a deep-sea squid (Grimalditeuthis bonplandi) and found it that appears to lure its prey by flapping and fluttering its tentacle tips, or clubs. The researchers hypothesized that the motion of the clubs may induce small shrimp and other animals to approach within reach of the squid's arms.

The squid uses a different feeding strategy than most other squid. A slow swimmer with a weak, gelatinous body, its tentacles are long, thin, fragile and too weak to capture prey. Unlike any other known squid, its tentacles do not have any suckers, hooks or photophores (glowing spots).

Video was taken from ROVs to monitor the squid in their native habitat at 1,000 to 2,000 meters depth. Scientists also analyzed video collected by several oil industry ROVs in the Gulf of Mexico. Instead of using its muscles to extend its tentacles, like most squids, G. bonplandi sends its clubs, swimming away from its body, dragging the tentacles behind them. After the tentacles are extended, the clubs continue to wiggle independently of the tentacles. The squid appear to give the impression that their clubs are small, swimming animals, independent from the rest of their bodies.

The researchers speculate that the motion of the clubs may induce smaller squids and shrimp to approach close enough to be captured by G. bonplandi's arms. When threatened, instead of retracting its tentacles as most squids would do, G. bonplandi swims down toward its clubs. After swimming alongside its clubs, the squid coils both the tentacles and clubs and hides them within its arms before swimming away.

Because the scientists have never seen the squid capture prey, they still do not know how it feeds on animals using its "swimming" tentacle tips.

Heavy-Metal Pollutants in Fish About Same In/Out of Oil Sites
A recent study by University of California, Santa Barbara (UCSB) scientists analyzed whole-body fish samples taken from oil and gas production platforms and natural sites for heavy-metal pollutants. The results showed all but four elements were relatively consistent at both types of location. The findings were published in the Bulletin of Marine Science.

The research entailed collecting a total of 196 fish—18 kelp bass (Paralabrax clathratus), 80 kelp rockfish (Sebastes atrovirens), and 98 Pacific sanddab (Citharichthys sordidus)—from five offshore oil platforms and 10 natural areas during 2005 and 2006. Samples were taken at 19 sites between the Santa Barbara Channel in the north and Long Beach in the south. Three of the offshore islands—Santa Cruz, Anacapa, and Catalina—provided some of the natural sites.

Of 63 elements, 42 were excluded from statistical comparisons because they were not detected during analysis, were detected at concentrations too low to yield reliable quantitative measurements, or were deemed unlikely to accumulate to potentially toxic concentrations. None of the remaining 21 elements consistently exhibited higher concentrations at oil platforms than at natural areas.


-back to top-

Sea Technology is read worldwide in more than 110 countries by management, engineers, scientists and technical personnel working in industry, government and educational research institutions. Readers are involved with oceanographic research, fisheries management, offshore oil and gas exploration and production, undersea defense including antisubmarine warfare, ocean mining and commercial diving.