115 resultados para Lea


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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 - the PLEA project. 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). Habitats were mapped using a combination of towed GPS photo transects, aerial photography and expert knowledge. This data provides georeferenced information regarding the major features of each of the Point Lookout Dive Sites.

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This theses investigates changes at Gepatschferner in length, area and volume since the last glacier maximum in 1850. Changes are discussed for the following time periods: 1850-1922, 1922-1971, 1971-1997, 1997-2006. Digital elevation models were created for 1850 from geomorphological data and for 1922 and 1971 from historical maps. Existing DEMs for 1997 and 2006 were further analysed. Since 1850 Gepatschferner has retreated by 2 km in length and has lost 32% of its area and 36% of its volume. The rate of loss of volume is increasing faster than the rate of loss of area and losses in the upper regions of the glacier are becoming increasingly more important to overall losses. The largest losses per 50 m elevation increment occur at the tongue. These losses are greatest in the most recent time step studied, 1997-2006, and exceed previous values by 40% and more. The data base includes the glacier margins, elevations models as they have been compiled within the thesis (DEMs of 1997 and 2006 are part of the glacier inventories, length changes are part of the length change data base of the Austrian Alpine Club).

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A new benthic foraminiferal Ba/Ca and Cd/Ca data set from core RC13-229 in the deep Cape Basin indicates only small variations in bottom water nutrient concentrations in Circumpolar Deep Water (CPDW) over the last 450 kyr. Variability in the Ba record is characterized by somewhat higher values during glacial periods, consistent with a reduction in the flux of Ba-depleted North Atlantic Deep Water to the Southern Ocean during glacial periods. The small changes in the Ba and Cd records contrast with the large and systematic increase in CPDW nutrients during glacial periods implied by the benthic delta13C record. This discrepancy, essentially an extension of the well-known Southern Ocean Cd-delta13C conflict, is evaluated by transforming RC13-229 paleochemical data into carbonate parameters using the modern oceanic relationships between delta13C, Cd, and SumCO2 and between Ba and alkalinity. Calculations using Cd/Ca to estimate past variations in CPDW SumCO2 and Ba/Ca to estimate past variations in CPDW alkalinity yield carbonate ion concentrations that exceed calcite saturation throughout the record length, with generally higher carbonate ion values associated with glacial intervals (opposite in sense to the RC13-229 %CaCO3 record). Substituting delta13C to estimate SumCO2 leads to extreme calcite undersaturation at this site during glacial periods, clearly inconsistent with the preservation of calcite throughout the length of RC13-229. Accepting the carbon isotope record as a direct measure of past variations in CPDW SumCO2 concentrations requires that both the Cd and Ba evidence for limited nutrient and alkalinity changes be disregarded.

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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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The chemical composition of shells of the planktonic foraminifer Globigerinoides ruber (white) is frequently used to determine past sea surface conditions. Recently, it has been shown that arbitrarily defined morphotypes within this species exhibit different chemical and isotopic signatures. Here, we investigate the occurrence through time and in space of morphological types of G. ruber (white) in late Quaternary and Holocene sediments of the central and the eastern Mediterranean Sea. In 115 samples representing two distinct time intervals (MIS 1-2 and MIS 9-12) at ODP Site 964 and the piston core GeoTü-SL96, we have defined three morphological types within this species and determined their relative abundances and stable isotopic composition. A quantitative analysis of morphological variation within G. ruber (white) in four samples revealed that the subjectively defined morphotypes occupy separate segments of a continuous and homogenous morphospace. We further show that the abundance of the morphotypes changes significantly between glacials and interglacials and that the three morphotypes of G. ruber show significant offsets in their stable isotopic composition. These offsets are consistent within glacial and interglacial stages but their sign is systematically reversed between the two Sites. Since the isotopic shifts among the three G. ruber morphotypes are systematic and often exceed 1per mil, their understanding is essential for the interpretation of all G. ruber-based proxy records for the paleoceanographic development of the Mediterranean during the late Quaternary.