Seagrass time-series analysis products, in Moreton Bay, Australia, with links to GeoTIFFs

The spatial and temporal dynamics of seagrasses have been well studied at the leaf to patch scales, however, the link to large spatial extent landscape and population dynamics is still unresolved in seagrass ecology. Traditional remote sensing approaches have lacked the temporal resolution and consistency to appropriately address this issue. This study uses two high temporal resolution time-series of thematic seagrass cover maps to examine the spatial and temporal dynamics of seagrass at both an inter- and intra-annual time scales, one of the first globally to do so at this scale. Previous work by the authors developed an object-based approach to map seagrass cover level distribution from a long term archive of Landsat TM and ETM+ images on the Eastern Banks (~200 km**2), Moreton Bay, Australia. In this work a range of trend and time-series analysis methods are demonstrated for a time-series of 23 annual maps from 1988 to 2010 and a time-series of 16 monthly maps during 2008-2010. Significant new insight was presented regarding the inter- and intra-annual dynamics of seagrass persistence over time, seagrass cover level variability, seagrass cover level trajectory, and change in area of seagrass and cover levels over time. Overall we found that there was no significant decline in total seagrass area on the Eastern Banks, but there was a significant decline in seagrass cover level condition. A case study of two smaller communities within the Eastern Banks that experienced a decline in both overall seagrass area and condition are examined in detail, highlighting possible differences in environmental and process drivers. We demonstrate how trend and time-series analysis enabled seagrass distribution to be appropriately assessed in context of its spatial and temporal history and provides the ability to not only quantify change, but also describe the type of change. We also demonstrate the potential use of time-series analysis products to investigate seagrass growth and decline as well as the processes that drive it. This study demonstrates clear benefits over traditional seagrass mapping and monitoring approaches, and provides a proof of concept for the use of trend and time-series analysis of remotely sensed seagrass products to benefit current endeavours in seagrass ecology.

Pollen distribution in marine sediment samples along the south-western African coast

The distribution of pollen in marine sediments is used to reconstruct pathways of terrigenous input to the oceans and provides a record of vegetation change on adjacent continents. The wind transport routes of aeolian pollen is comprehensively illustrated by clusters of trajectories. Isobaric, 4-day backward trajectories are calculated using the modelled wind-field of ECHAM3, and are clustered on a seasonal basis to estimate the main pathways of aeolian particles to sites of marine cores in the south-eastern Atlantic. Trajectories and clusters based on the modelled wind-field of the Last Glacial Maximum hardly differ from those of the present-day. Trajectory clusters show three regional, and two seasonal patterns, determining the pathways of aeolian pollen transport into the south-eastern Atlantic ocean. Mainly, transport out of the continent occurs during austral fall and winter, when easterly and south-easterly winds prevail. South of 25°S, winds blow mostly from the west and southwest, and aeolian terrestrial input is very low. Generally, a good latitudinal correspondence exists between the distribution patterns of pollen in marine surface sediments and the occurrence of the source plants on the adjacent continent. The northern Angola Basin receives pollen and spores from the Congolian and Zambezian forests mainly through river discharge. The Zambezian vegetation zone is the main source area for wind-blown pollen in sediments of the Angola Basin, while the semi-desert and desert areas are the main sources for pollen in sediments of the Walvis Basin and on the Walvis Ridge. A transect of six marine pollen records along the south-western African coast indicates considerable changes in the vegetation of southern Africa between glacial and interglacial periods. Important changes in the vegetation are the decline of forests in equatorial Africa and the north of southern Africa and a northward shift of winter rain vegetation along the western escarpment.

Mineralogical and stable isotope analyses of carbonates from the eastern Black Sea

Authigenic carbonates associated with cold seeps provide valuable archives of changes in the long-term seepage activity. To investigate the role of shallow-buried hydrates on the seepage strength and fluid composition we analysed methane-derived carbonate precipitates from a high-flux hydrocarbon seepage area ("Batumi seep area") located on the south-eastern Black Sea slope in ca. 850 m. In a novel approach, we combined computerized X-ray tomography (CT) with mineralogical and isotope geochemical methods to get additional insights into the three-dimensional internal structure of the carbonate build-ups. X-ray diffractometry revealed the presence of two different authigenic carbonate phases, i.e. pure aragonitic rims associated with vital microbial mats and high-Mg calcite cementing the hemipelagic sediment. As indicated by the CT images, the initial sediment has been strongly deformed, first plastic then brittle, leading to brecciation of the progressively cemented sediment. The aragonitic rims on the other hand, represent a presumably recent carbonate growth phase since they cover the already deformed sediment. The stable oxygen isotope signature indicates that the high-Mg calcite cement incorporated pore water mixed with substantial hydrate water amounts. This points at a dominant role of high gas/fluid flux from decomposing gas hydrates leading to the deformation and cementation of the overlying sediment. In contrast, the aragonitic rims do not show an influence of 18O-enriched hydrate water. The differences in d18O between the presumably recent aragonite precipitates and the older high-Mg cements suggest that periods of hydrate dissociation and vigorous fluid discharge alternated with times of hydrate stability and moderate fluid flow. These results indicate that shallow-buried gas hydrates are prone to episodic decomposition with associated vigorous fluid flow. This might have a profound impact on the seafloor morphology resulting e.g. in the formation of carbonate pavements and pockmark-like structures but might also affect the local carbon cycle.

Diatom abundance and fatty acid composition of ice algae and of Calanus glacialis in samples obtained in 2008 in the eastern Beaufort Sea

The copepod Calanus glacialis plays a key role in the lipid-based energy flux in Arctic shelf seas. By utilizing both ice algae and phytoplankton, this species is able to extend its growth season considerably in these seasonally ice-covered seas. This study investigated the impacts of the variability in timing and extent of the ice algal bloom on the reproduction and population success of C. glacialis. The vertical distribution, reproduction, amount of storage lipids, stable isotopes, fatty acid and fatty alcohol composition of C. glacialis were assessed during the Circumpolar Flaw Lead System Study. Data were collected in the Amundsen Gulf, south-eastern Beaufort Sea, from January to July 2008 with the core-sampling from March to April. The reduction in sea ice thickness and coverage observed in the Amundsen Gulf in 2007 and 2008 affected the life strategy and reproduction of C. glacialis. Developmental stages CIII and CIV dominated the overwintering population, which resulted in the presence of very few CV and females during spring 2008. Spawning began at the peak of the ice algal bloom that preceded the precocious May ice break-up. Although the main recruitment may have occurred later in the season, low abundance of females combined with a potential mismatch between egg production/development to the first feeding stage and phytoplankton bloom resulted in low recruitment of C. glacialis in the early summer of 2008.

2003 Habitat Maps derived from Grey Nurse Shark (GNS) Project of Wolf Rock, Double Island Point, Queensland, Australia

Surveying habitats critical to the survival of grey nurse sharks in South-East Queensland has mapped critical habitats, gathered species inventories and developed protocols for ecological monitoring of critical habitats in southern Queensland. This information has assisted stakeholders with habitat definition and effective management. In 2002 members of UniDive applied successfully for World Wide Fund for Nature, Threatened Species Network funds to map the critical Grey Nurse Shark Habitats in south east Queensland. UniDive members used the funding to survey, from the boats of local dive operators, Wolf Rock at Double Island Point, Gotham, Cherub's Cave, Henderson's Rock and China Wall at North Moreton and Flat Rock at Point Look Out during 2002 and 2003. These sites are situated along the south east Queensland coast and are known to be key Grey Nurse Shark aggregation sites. During the project UniDive members were trained in mapping and survey techniques that include identification of fish, invertebrates and substrate types. Training was conducted by experts from the University of Queensland (Centre of Marine Studies, Biophysical Remote Sensing) and the Queensland Parks and Wildlife Service who are also UniDive members. The monitoring methods (see methods) are based upon results of the UniDive Coastcare project from 2002, the international established Reef Check program and research conducted by Biophysical Remote Sensing and the Centre of Marine Studies. Habitats were mapped using a combination of towed GPS photo transects, aerial photography, bathymetry surveys and expert knowledge. This data provides georeferenced information regarding the major features of each of Sites mapped including Wolf Rock

Sedimentology, magnetics and chemistry on palaeolake core D100 from the Gobi Desert

The Gaxun Nur Basin in arid China is tectonically influenced by the left-lateral displacements along the Gobi-Altay and Qilian Shan shear zones, resulting in a large pull-apart basin with strong subsidence in the interior. The up to 300 m thick basin fills consist of fluvio-lacustrine fine-grained deposits mainly transported by river discharges from the Tibetan Plateau. They led to a large depositional area of more than 28,000 qkm in size with presently dry terminal lakes at the outer edges. This vast area serves as a main source for loess transport to south-eastern regions of China (Loess Plateau) caused by the variable winter monsoon. Based on geochemical and sedimentological analyses of the sediment core D100 retrieved from a deep drilling in the centre of the Gaxun Nur Basin following questions have to be answered: 1. Reconstruction of the water balance and determination of hydrological cycles during interglacial and glacial periods. 2. Reconstructing variations in lacustrine environment and aeolian activities with respect to transitional phases fro, warm to cold stages (MIS 4 to 5 and older stages). 3. Establishing a sustainable chronology for the last 250 ka.

Chemical element contents and accumulation rates in metalliferous sediments from DSDP Hole 34-319, Bauer Deep, Southeast Pacific

Marked variations in the chemical and mineralogical composition of sediments at Site 319 have occurred during the 15 My history of sedimentation at this site. The change in composition through time parallels the variability observed in surface sediments from various parts of the Nazca Plate and can be related to variations in the proportion of hydrothermal, hydrogenous, detrital and biogenous phases reaching this site at different times. Metal accumulation rates at Site 319 reach a maximum near the basement for most elements, suggesting a strong hydrothermal contribution during the early history of this site. The hydrothermal contribution decreased rapidly as Site 319 moved away from the spreading center, although a subtle increase in this source is detectable about the time spreading began on the East Pacific Rise. The most recent sedimentation exhibits a strong detritalhydrogenous influence. Post-depositional diagenesis of amorphous phases has converted them to ironrich smectite and well-crystallized goethite without significantly altering the bulk composition of the sediment.

Probability inundation map for a scenario combining storm surge and sea-level rise

Coastal managers require reliable spatial data on the extent and timing of potential coastal inundation, particularly in a changing climate. Most sea level rise (SLR) vulnerability assessments are undertaken using the easily implemented bathtub approach, where areas adjacent to the sea and below a given elevation are mapped using a deterministic line dividing potentially inundated from dry areas. This method only requires elevation data usually in the form of a digital elevation model (DEM). However, inherent errors in the DEM and spatial analysis of the bathtub model propagate into the inundation mapping. The aim of this study was to assess the impacts of spatially variable and spatially correlated elevation errors in high-spatial resolution DEMs for mapping coastal inundation. Elevation errors were best modelled using regression-kriging. This geostatistical model takes the spatial correlation in elevation errors into account, which has a significant impact on analyses that include spatial interactions, such as inundation modelling. The spatial variability of elevation errors was partially explained by land cover and terrain variables. Elevation errors were simulated using sequential Gaussian simulation, a Monte Carlo probabilistic approach. 1,000 error simulations were added to the original DEM and reclassified using a hydrologically correct bathtub method. The probability of inundation to a scenario combining a 1 in 100 year storm event over a 1 m SLR was calculated by counting the proportion of times from the 1,000 simulations that a location was inundated. This probabilistic approach can be used in a risk-aversive decision making process by planning for scenarios with different probabilities of occurrence. For example, results showed that when considering a 1% probability exceedance, the inundated area was approximately 11% larger than mapped using the deterministic bathtub approach. The probabilistic approach provides visually intuitive maps that convey uncertainties inherent to spatial data and analysis.

Middle Miocene to recent sedimentological record of ODP sites 177-1088 and 177-1092

During Leg 177 of the Ocean Drilling Program (ODP), well-preserved Middle Miocene to Pleistocene carbonate-rich sediment records were recovered on a north-south transect through the south-eastern Atlantic sector of the Southern Ocean at Site 1088 on the Agulhas Ridge and Site 1092 on Meteor Rise. Both sites were dominated by the deposition of calcareous nannofossil oozes through the Miocene, indicating low biological productivity in warm to temperate surface waters. A continuous increase in the proportions of foraminifera since the latest Miocene (6.5 Ma) points to enhanced nutrient supply, possibly related to the global 'biogenic bloom' event across the Miocene-Pliocene boundary. Since the Late Pliocene, different styles of biological productivity developed between the sites. Enhanced deposition of biosiliceous constituents at the southern Site 1092, particularly in the Early Pleistocene, is consistent with the formation of the Circum-Antarctic Opal Belt since 2.5 Ma in a setting near the Polar Front, whereas carbonate deposition still prevailed at the northern Site 1088 situated near the Subtropical Front. Clay-mineral tracers of water-mass advection together with the pattern of sedimentation rates and hiatuses reflect distinct pulses in the development of regional ocean circulation between 14 and 12 Ma, around 8 Ma and since 2.8 Ma. These pulses can be related to Antarctic ice-sheet extension that mediates the production and flow of southern source water, and stepwise increases in North Atlantic Deep Water production that drives global conveyor circulation. At Site 1088, illite chemistry and silt/clay ratios of the terrigenous sediment fraction reflect the history of terrestrial climate in southern Africa, with humid conditions prior to the Early Late Miocene (9.7 Ma), followed by a dry episode until 7.7 Ma. The latest Miocene and Early Pliocene were characterized by a humid episode until modern aridity was established in the Late Pliocene between 4.0 and 2.8 Ma. These climate changes were related to the latitudinal migration of climate belts in response to tectonically caused reorganizations in atmospheric and ocean circulation.