980 resultados para marine fauna


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he exploration of the Gulf Stream region was continued in 1884, under nearly the same conditions as in 1883, by the steamer Albatross, Lieut. Z. L. Tanner, commander. During the four trips, between July 20 and Sept. 13, sixty nine dredgings (at stations 2170 to 2238) were made. The results were highly satisfactory, both in the way of physical observatidns and zoological discoveries. In some localities, in 1000 to 1600 fathoms, the bottom was found covered with 0or largely composed of hard, very irregular, flattened, crust-like concretions of clay and iron-oxide, with more or less manganese?oxide in the crevices and worm-burrows with which they are filled. Sometimes a barrel-full, or more, of such masses were brought up, varying in size from a few ounces up to 20 pounds or more in weight alld from one inch to six inches in thickness.

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Himalayacetus subathuensis is a new pakicetid archaeocete from the Subathu Formation of northern India. The type dentary has a small mandibular canal indicating a lack of auditory specializations seen in more advanced cetaceans, and it has Pakicetus-like molar teeth suggesting that it fed on fish. Himalayacetus is significant because it is the oldest archaeocete known and because it was found in marine strata associated with a marine fauna. Himalayacetus extends the fossil record of whales about 3.5 million years back in geological time, to the middle part of the early Eocene [≈53.5 million years ago (Ma)]. Oxygen in the tooth-enamel phosphate has an isotopic composition intermediate between values reported for freshwater and marine archaeocetes, indicating that Himalayacetus probably spent some time in both environments. When the temporal range of Archaeoceti is calibrated radiometrically, comparison of likelihoods constrains the time of origin of Archaeoceti and hence Cetacea to about 54–55 Ma (beginning of the Eocene), whereas their divergence from extant Artiodactyla may have been as early as 64–65 Ma (beginning of the Cenozoic).

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The Kap Mackenzie area on the outer coast of northeast Greenland was glaciated during the last glacial stage, and pre-Holocene shell material was brought to the area. Dating of marine shells indicates that deglaciation occurred in the earliest Holocene, before 10 800 cal. a BP. The marine limit is around 53 m a.s.l. In the wake of the deglaciation, a glaciomarine fauna characterized the area, but after c. one millennium a more species-rich marine fauna took over. This fauna included Mytilus edulis and Mysella sovaliki, which do not live in the region at present; the latter is new to the Holocene fauna of northeast Greenland. The oldest M. edulis sample is dated to c. 9500 cal. a BP, which is the earliest date for the species from the region and indicates that the Holocene thermal maximum began earlier in the region than previously documented. This is supported by driftwood dated to c. 9650 cal. a BP, which is the earliest driftwood date so far from northeastern Greenland and implies that the coastal area was at least partly free of sea ice in summer. As indicated by former studies, the Storegga tsunami hit the Kap Mackenzie area at c. 8100 cal. a BP. Loon Lake, at 18 m a.s.l., was isolated from the sea at c. 6200 cal. a BP, which is distinctly later than expected from existing relative sea-level curves for the region.

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Bouvet (Bouvetøya) is a geologically young and very remote island just south of the Polar Front. Here we report samples taken during the RV "Polarstern" cruise ANTXXI/2 on 3 days in November 2003 and January 2004. This work was part of SCAR's EASIZ programme and intended, by providing data on the marine fauna of this "white gap" in the Atlantic sector of the Southern Ocean, to contribute to identifying the role of Bouvet in the faunal exchange between the Sub- and high Antarctic. While this goal demands extensive molecular analysis of the material sampled (future work), a checklist of the samples and data at hand widens the faunal and environmental inventory substantially. We suggest some preliminary conclusions on the relationship of Bouvet Island's fauna with that of other regions, such as Magellanic South America, the Antarctic Peninsula, and the high Antarctic Weddell Sea, which have been sampled previously. There seem to be different connections for individual higher taxa rather than a generally valid consistent picture.

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Since 1949, The Nha Trang Institute of Oceanography has undertaken an inventory of Vietnamese marine fauna with reference to its collection kept in Nha Trang. The collection contains about 250 species of Brachyura. Rare species of particular interest are described in this note.

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The main purpose of the Oceanographic Institute of Nhatrang aimed to make an inventory of the marine fauna of Vietnam in order to increase the collection kept at the National Museum. The present note deals with detailed descriptions 32 species of hermit crabs belonging to the family of Paguridae collected on the Vietnamese coasts.

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It is very difficult to make paleoclimatic correlations between continental and marine areas, but it is possible with biostratigraphic data. Reliable correlations can be made only between broad periods: between 3.5 and 3 Ma, around 2.4 Ma, until 1.6 Ma and after 1.6 Ma. The arid Mediterranean phases led to the disappearance of the European Villafranchian fauna (1.0 Ma).

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In 2014, UniDive (The University of Queensland Underwater Club) conducted an ecological assessment of the Point Lookout Dive sites for comparison with similar surveys conducted in 2001. Involvement in the project was voluntary. Members of UniDive who were marine experts conducted training for other club members who had no, or limited, experience in identifying marine organisms and mapping habitats. Since the 2001 detailed baseline study, no similar seasonal survey has been conducted. The 2014 data is particularly important given that numerous changes have taken place in relation to the management of, and potential impacts on, these reef sites. In 2009, Moreton Bay Marine Park was re-zoned, and Flat Rock was converted to a marine national park zone (Green zone) with no fishing or anchoring. In 2012, four permanent moorings were installed at Flat Rock. Additionally, the entire area was exposed to the potential effects of the 2011 and 2013 Queensland floods, including flood plumes which carried large quantities of sediment into Moreton Bay and surrounding waters. The population of South East Queensland has increased from 2.49 million in 2001 to 3.18 million in 2011 (BITRE, 2013). This rapidly expanding coastal population has increased the frequency and intensity of both commercial and recreational activities around Point Lookout dive sites (EPA 2008). Methodology used for the PLEA project was based on the 2001 survey protocols, Reef Check Australia protocols and Coral Watch methods. This hybrid methodology was used to monitor substrate and benthos, invertebrates, fish, and reef health impacts. Additional analyses were conducted with georeferenced photo transects. The PLEA marine surveys were conducted over six weekends in 2014 totaling 535 dives and 376 hours underwater. Two training weekends (February and March) were attended by 44 divers, whilst biological surveys were conducted on seasonal weekends (February, May, July and October). Three reefs were surveyed, with two semi-permanent transects at Flat Rock, two at Shag Rock, and one at Manta Ray Bommie. Each transect was sampled once every survey weekend, with the transect tapes deployed at a depth of 10 m below chart datum. Fish populations were assessed using a visual census along 3 x 20 m transects. Each transect was 5 m wide (2.5 m either side of the transect tape), 5 m high and 20 m in length. Fish families and species were chosen that are commonly targeted by recreational or commercial fishers, or targeted by aquarium collectors, and that were easily identified by their body shape. Rare or otherwise unusual species were also recorded. Target invertebrate populations were assessed using visual census along 3 x 20 m transects. Each transect was 5 m wide (2.5 m either side of the transect tape) and 20 m in length. The diver surveying invertebrates conducted a 'U-shaped' search pattern, covering 2.5 m on either side of the transect tape. Target impacts were assessed using a visual census along the 3 x 20 m transects. Each transect was 5 m wide (2.5 m either side of the transect tape) and 20 m in length. The transect was surveyed via a 'U-shaped' search pattern, covering 2.5 m on either side of the transect tape. Substrate surveys were conducted using the point sampling method, enabling percentage cover of substrate types and benthic organisms to be calculated. The substrate or benthos under the transect line was identified at 0.5m intervals, with a 5m gap between each of the three 20m segments. Categories recorded included various growth forms of hard and soft coral, key species/growth forms of algae, other living organisms (i.e. sponges), recently killed coral, and, non-living substrate types (i.e. bare rock, sand, rubble, silt/clay).

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Extracted from the Philippine Journal of Science, v.18, no.1.

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"May 1976"

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Mode of access: Internet.