1,721,156 research outputs found
Disposal in the deep sea: analogue of nature or faux ami?
No full textThe deep sea is the world's largest ecosystem by volume and is assumed to have a high assimilative capacity. Natural events, such as the sinking of surface plant and animal material to the seabed, sediment slides, benthic storms and hydrothermal vents can contribute vast amounts of material, both organic and inorganic, to the deep ocean. In the past the deep sea has been used as a repository for sewage, dredge spoil and radioactive waste. In addition, there has been interest in the disposal of large man-made objects and, more recently, the disposal of industrially-produced carbon dioxide. Some of the materials disposed of in the deep sea may have natural analogues. This review examines natural processes in the deep sea including the vertical flux of organic material, turbidity currents and benthic storms, natural gas emissions, hydrothermal vents, natural radionuclides and rocky substrata, and compares them with anthropogenic input including sewage disposal, dredge spoil, carbon dioxide disposal, chemical contamination and the disposal of radioactive waste, wrecks and rigs. The comparison shows what are true analogues and what are false friends. Knowledge of the deep sea is fragmentary and much more needs to be known about this large, biologically-diverse system before any further consideration is given to its use in the disposal of waste
Deep-Sea Eukaryote Ecology of the Semi-Isolated Basins Off Japan
No full textThe Japanese archipelago is surrounded by the Pacific to the east, the Okhotsk Sea to the north, the Sea of Japan to the west and the Okinawa Trough to the south. The last three seas form semi-isolated deep basins, all with potentially tectonic origin but a different primary energy source as well as hydrographic and faunistic history. The Okhotsk Sea is connected to the Pacific through the deep straits between the Kurile Islands. As a result much of the fauna has links with that fauna found at similar depths in the Pacific. By contrast, the Sea of Japan was isolated from the main Pacific during the last ice age and became anoxic. Even today the link is only through narrow shallow straits. As a result the fauna is impoverished and is believed to be composed of cold-adapted eurybathic species rather than true deep-sea species. The deep-water fauna of both these seas derive their energy from sinking surface primary production. The Okinawa Trough has a much younger tectonic history than the Okhotsk Sea or the Sea of Japan. In the Okinawa Trough the most noticeable fauna is associated with hydrothermal activity and chemosynthesis forms the base of the food chain for the bathyal community. The variable nature of these three basins offers excellent opportunities for comparative studies of species diversity, biomass and production in relation to their ambient environmen
The reproductive biology of two deep-water, reef-building scleractinians from the NE Atlantic Ocean
No full textThe reproductive ecology of colonies of Lophelia pertusa (Linné 1758) and Madrepora oculata Linné (1758) from the Porcupine Seabight (Thérèse Mound and South Porcupine Seabight site) and the Darwin Mounds (NE Rockall Trough—L. pertusa only) was investigated using histological techniques. Samples of L. pertusa exhibited seasonal reproduction, whereas the evidence for M. oculata is equivocal but suggests multiple cohorts of gamete production. L. pertusa produces a single cohort of around 3,000 oocytes, whereas M. oculata produces two cohorts, with a total fecundity of around 60 oocytes. The maximum observed oocyte size in L. pertusa was 140 ?m and in M. oculata was 405 ?m. From these oocyte sizes and the timing of reproduction, a lecithotrophic larva is expected, though not observed. This seasonality of reproduction fits with the phytodetrital food fall occurring around July in the Seabight area. L. pertusa was found to be non-reproductive at the Darwin Mound site. Though unable to be specifically tested, this may suggest that the increased trawling activity in this area might be keeping colonies below sexually viable sizes, as seen in numerous shallow water situations. All areas in the NE Atlantic are coming under threat from increased fishing and commercial exploration practices. This study shows that these highly seasonal reproducers could be sensitive to these fishing operations and care must be taken so as not to repeat the destruction that has occurred on shallower reefs
Temperature/pressure tolerance of the first larval stage of Mirocaris fortunata from Lucky Strike hydrothermal vent field
No full textHydrothermal plume processes in the Indian Ocean (Kairei and Edmond vent-sites, Central Indian Ridge) (abstract of paper presented at ASLO/AGU Ocean Sciences Meeting, Honolulu, HI, 11-15 Feb 2002)
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