Biology of modern Fragum erugatum (Mollusca, Bivalvia, Cardiidae) in relation to deposition of the Hamelin Coquina, Shark Bay, Western Australia

1997 ◽  
Vol 48 (5) ◽  
pp. 415 ◽  
Author(s):  
P. F. Berry ◽  
P. E. Playford
Keyword(s):  
Western Australia ◽  
Large Scale ◽  
Gill Tissue ◽  
Shell Shape ◽  
Size Distributions ◽  
Storm Events ◽  
Shark Bay ◽  
Scale Deposition

Fragum erugatum populations were sampled over two consecutive years in Hamelin Pool, Lharidon Bight and Freycinet Harbour, which are representative of the hypersaline and metahaline regimes of Shark Bay. F. erugatum was widely distributed infratidally between 1.2 m and 6.5 m depth. Dense aggregations of zooxanthellae were present in mantle and gill tissue. Shell shape of the population from Hamelin Pool differs from that of the Lharidon Bight, Freycinet Harbour and Dampier Archipelago populations. F. erugatum was found to be a synchronous hermaphrodite. Settlements of juveniles, and modality of size distributions, indicate a single annual spawning. Production estimates of dry flesh and shell (CaCO3 inclusive) were much lower in Hamelin Pool than in Lharidon Bight, largely because of the lower density of F. erugatum recorded in Hamelin Pool. Although shells are washed ashore continuously, large-scale deposition of the accumulated infratidal coquinas, largely composed of F. erugatum shells, probably occurs periodically in major storm events, thereby forming the Hamelin Coquina.

The distribution and abundance of the dugong in Shark Bay, Western Australia

1994 ◽  
Vol 21 (2) ◽  
pp. 149 ◽  
Author(s):  
H Marsh ◽  
RIT Prince ◽  
WK Saafeld ◽  
R Shepherd
Keyword(s):  
Western Australia ◽  
Large Scale ◽  
Correction Factors ◽  
Water Turbidity ◽  
Shark Bay ◽  
Northern Half ◽  
Perception Bias ◽  
Calving Rate ◽  
Specific Correction ◽  
Eastern Half

In July 1989, dugongs were counted from the air at an overall sampling intensity of 7.9% over 14 239 km2 in Shark Bay, Western Australia. Counts were corrected for perception bias (the proportion of dugongs visible in the transect that are missed by observers), and standardised for availability bias (the proportion of animals invisible because of water turbidity) with survey-specific correction factors. The resultant minimum population estimate was 10146 � 1665 (s.e.) dugongs at an overall density of 0.71 � 0.12 (s.e.) dugongs km-2, the highest density ever recorded on a large-scale dugong survey. The proportion of calves (19%) was higher than for most other dugong surveys conducted in Shark Bay and elsewhere, suggesting an exceptionally high calving rate in 1988. Dugong density was highest (>5 km-2) in relatively deep water (12-16 m) in the eastern half of Shark Bay opposite the tip of Peron Peninsula and in the western Bay opposite the northern half of Dirk Hartog Island. Fewer than 4% of dugongs sighted in Shark Bay during the survey were in waters colder than 18�C. Results of aerial surveys over 906 km2 in the Faure Sill region of the eastern Bay in November 1990 and January 1991 suggest that between a third and a half of the dugongs in Shark Bay are located in this region during the summer. In contrast, only one dugong was sighted there during the winter survey. The survey confirms that Shark Bay is an internationally significant dugong habitat.

scholarly journals Large‐scale eDNA metabarcoding survey reveals marine biogeographic break and transitions over tropical north‐western Australia

2021 ◽  
Author(s):  
Katrina West ◽  
Michael J. Travers ◽  
Michael Stat ◽  
Euan S. Harvey ◽  
Zoe T. Richards ◽  
...  
Keyword(s):  
Western Australia ◽  
Large Scale ◽  
North Western

scholarly journals Additive-Enhanced Exfoliation for High-Yield 2D Materials Production

Nanomaterials ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 601
Author(s):  
Dinh-Tuan Nguyen ◽  
Hsiang-An Ting ◽  
Yen-Hsun Su ◽  
Mario Hofmann ◽  
Ya-Ping Hsieh
Keyword(s):  
Large Scale ◽  
2D Materials ◽  
Transition Metal Dichalcogenides ◽  
Spectroscopic Characterization ◽  
High Yield ◽  
Nanometer Scale ◽  
Efficient Production ◽  
Device Performance ◽  
Metal Dichalcogenides ◽  
Scale Deposition

The success of van-der-Waals electronics, which combine large-scale-deposition capabilities with high device performance, relies on the efficient production of suitable 2D materials. Shear exfoliation of 2D materials’ flakes from bulk sources can generate 2D materials with low amounts of defects, but the production yield has been limited below industry requirements. Here, we introduce additive-assisted exfoliation (AAE) as an approach to significantly increase the efficiency of shear exfoliation and produce an exfoliation yield of 30%. By introducing micrometer-sized particles that do not exfoliate, the gap between rotor and stator was dynamically reduced to increase the achievable shear rate. This enhancement was applied to WS2 and MoS2 production, which represent two of the most promising 2D transition-metal dichalcogenides. Spectroscopic characterization and cascade centrifugation reveal a consistent and significant increase in 2D material concentrations across all thickness ranges. Thus, the produced WS2 films exhibit high thickness uniformity in the nanometer-scale and can open up new routes for 2D materials production towards future applications.

Integration of Cretaceous Morro do Chaves rock properties (NE Brazil) with the Holocene Hamelin Coquina architecture (Shark Bay, Western Australia) to model effective permeability

2016 ◽  
Vol 22 (2) ◽  
pp. 105-122 ◽  
Author(s):  
Patrick W. M. Corbett ◽  
Rayana Estrella ◽  
Andrea Morales Rodriguez ◽  
Ahmed Shoeir ◽  
Leonardo Borghi ◽  
...  
Keyword(s):  
Western Australia ◽  
Effective Permeability ◽  
Rock Properties ◽  
The Holocene ◽  
Shark Bay

Change in abundance of dugongs in Shark Bay, Ningaloo and Exmouth Gulf, Western Australia: evidence for large-scale migration

2004 ◽  
Vol 31 (3) ◽  
pp. 283 ◽  
Author(s):  
Nick Gales ◽  
Robert D. McCauley ◽  
Janet Lanyon ◽  
Dave Holley
Keyword(s):  
Marine Protected Areas ◽  
Large Scale ◽  
Population Demographics ◽  
Shark Bay ◽  
Ningaloo Reef ◽  
Aerial Surveys ◽  
Large Numbers ◽  
Plausible Hypothesis ◽  
Exmouth Gulf ◽  
Regional Abundance

The third in a series of five-yearly aerial surveys for dugongs in Shark Bay, Ningaloo Reef and Exmouth Gulf was conducted in July 1999. The first two surveys provided evidence of an apparently stable population of dugongs, with ~1000 animals in each of Exmouth Gulf and Ningaloo Reef, and 10 000 in Shark Bay. We report estimates of less than 200 for each of Exmouth Gulf and Ningaloo Reef and ~14 000 for Shark Bay. This is an apparent overall increase in the dugong population over this whole region, but with a distributional shift of animals to the south. The most plausible hypothesis to account for a large component of this apparent population shift is that animals in Exmouth Gulf and Ningaloo Reef moved to Shark Bay, most likely after Tropical Cyclone Vance impacted available dugong forage in the northern habitat. Bias associated with survey estimate methodology, and normal changes in population demographics may also have contributed to the change. The movement of large numbers of dugongs over the scale we suggest has important management implications. First, such habitat-driven shifts in regional abundance will need to be incorporated in assessing the effectiveness of marine protected areas that aim to protect dugongs and their habitat. Second, in circumstances where aerial surveys are used to estimate relative trends in abundance of dugongs, animal movements of the type we propose could lead to errors in interpretation.

scholarly journals Effects of different weed cutting methods on physical and hydromorphological conditions in lowland streams

2021 ◽  
pp. 10
Author(s):  
Jes Jessen Rasmussen ◽  
Helena Kallestrup ◽  
Kirstine Thiemer ◽  
Anette Baisner Alnøe ◽  
Lisbeth Dalsgaard Henriksen ◽  
...  
Keyword(s):  
Habitat Quality ◽  
Large Scale ◽  
Aquatic Plant ◽  
Quality Parameters ◽  
Storm Events ◽  
Short Term ◽  
Lowland Streams ◽  
Plant Removal ◽  
Flooding Events ◽  
Cutting Intensity

Climate change has increased the frequency and intensity of stream flooding events. In response, managing authorities may increase frequency and intensity of aquatic plant removal (weed cutting) to lower the water level in rivers possibly impairing physical and hydromorphological stream conditions. We studied 32 Danish lowland streams subjected to three different weed cutting practices, representing a gradient in weed cutting intensity, and uncut controls to compare physical and hydromorphological habitat quality parameters among stream groups. Moreover, we measured short-term changes in dissolved oxygen (DO) concentrations and suspended sediment (SS) transport in two streams before, during, and just after weed cutting for the least and most pervasive weed cutting method, respectively. Our results indicated a lower habitat quality affiliated with increasing intensity of weed cutting practice, notably an association with silt cover at the expense of hard substrate. DO concentrations were relatively unaltered but an abrupt increase in SS transport comparable to storm events was observed during cutting with the most pervasive method. Our results indicate that ecological and hydromorphological effects of high intensity weed cutting should be carefully studied and considered before large scale implementation.

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