Distribution of foraminifera in a macrotidal tropical estuary: Port Darwin, Northern Territory of Australia

1987 ◽  
Vol 38 (2) ◽  
pp. 249 ◽  
Author(s):  
MG Michie
Keyword(s):  
Coral Reef ◽  
Continental Shelf ◽  
Tidal Flat ◽  
Northern Territory ◽  
Tidal Currents ◽  
Tidal Range ◽  
Tropical Estuary ◽  
Symbiotic Algae ◽  
Reefal Facies

The foraminifera are distributed throughout Port Darwin and differ according to biotope. The tidal flat and coral reef biotopes are basically undisturbed, and contain species of foraminifera typical of those environments. Turbidity is responsible for a lower diversity of the reefal facies, and particularly affects those species with symbiotic algae. The reworked biotope contains foraminifera more typical of the shallow continental shelf. Strong tidal currents associated with the large tidal range are responsible for the reworking of sediments and foraminifera1 tests from inside and outside Port Darwin.

scholarly journals Les rivages des Bermudes et les formes littorales de dissolution du calcaire

2005 ◽  
Vol 2 (2) ◽  
pp. 115-137 ◽  
Author(s):  
François Taillefer
Keyword(s):  
Coral Reef ◽  
Coral Reefs ◽  
Mechanical Action ◽  
Intermediate Position ◽  
Striking Feature ◽  
Tidal Range ◽  
Intermediate Type ◽  
North East ◽  
The North

The littoral morphology of the Bermudas is an erosional morphology in limestones, the main processes being mechanical action and solution. The temperatures, in January and February, of the waters washing the Bermudas, are low enough to prevent the growing of true coral reefs. Therefore, it is not the morphology of a coral reef. The predominance of wave-cut cliffs is the most striking feature, despite the low and gently rolling topography. There are, however, other types of coasts on the islands, the mangrove being found on many sheltered shores. The writer thus opposes the sheltered shores of the sounds to the ones exposed on the southcoast, while the shores of the north and north-east coasts belong to an intermediate type. The steplike arrangement of the coastal forms of solution of the Bermudas limestones is primarily linked to the amount of the tidal range. These features are similar to those described on the shores of the warm seas, where the tide is negligible or weak. The Bermudas occupy an intermediate position between the regions where reefs are built by corals, and those, to the north, where solution, helped by other processes, occurs without compensation.

scholarly journals Quaternary benthic Foraminifera in the Tu Chinh - Vung May marine areas (continental shelf of Vietnam) and island, coral reef regions of the Truong Sa archipelago, Vietnam and their significance

2019 ◽  
Vol 19 (3B) ◽  
pp. 137-147
Author(s):  
Nguyen Ngoc ◽  
Bui Thi Luan ◽  
Nguyen Thi Hong Nhung
Keyword(s):  
Coral Reef ◽  
Continental Shelf ◽  
Benthic Foraminifera ◽  
Common Species ◽  
Subtropical Climate ◽  
Stratigraphic Division ◽  
Reef Islands ◽  
Sea Level Fluctuation ◽  
Marine Areas ◽  
Sediment Age

The results of identifying and studying micropaleontological samples from the Quaternary sediments in the Tu Chinh - Vung May marine areas (1) and some coral reef islands of Truong Sa archipelago (2) have found more than 300 species of Benthic foraminifera, in which 291 species have been studied and described in detail, belonging to 112 genera, 43 families, 5 orders and 3 classes of the phylum Foraminifera. Among them, there are 19 new species, 3 new subspecies and 3 new genera. In the first region there are 195 species and the second one - 121 species (including 25 common species for both regions). They have important significations in the stratigraphic-biostratigraphic, ecological, paleogeographic studies, in sedimentary lithology... Regarding stratigraphy, the characteristic of Pleistocene is the first emergence of four genera: Baculogypsina, Cymbaloporetta, Parasorites, and Schlumbergerella; for Holocene - the appearance of the following genera: Ammomassilina, Baulogypsinoides, Cymbaloporella, Falsotextularia, Fijiella, Flintina, Gyroidina, Lugdunum, Neoconorbina, Planoperculina, Ptychomiliolata, Pseudoflintina, Pseudomassilina, Sahulia, Schlumbergerina, Septotextularia, Siphoniferoides, Tawitawia and Truongsaia. These fossils are the basis for dating sediment age, Quaternary stratigraphic division and correlation. In terms of paleoecology, benthic Foraminifera in the region (1) characterize the shallow offshore environment of the continental shelf, where there are the high and stable salinity, and the relatively strong environmental dynamics; in some places there are coral reef Foraminifera populations. In the region (2), they characterize the coral reef ecosystem of shallow and warm sea areas in the belt of tropical-subtropical climate of the Earth, where the salinity is high and stable, the transparency of water is high, and the environmental dynamics is relatively strong to strong... In addition, the paper also mentioned some other issues such as paleogeography (sea-level fluctuation), value of creating sediments of Foraminifera, environmental monitoring (for modern Foraminifera).

Moon and tide effects on fish capture in a tropical tidal flat

2010 ◽  
Vol 91 (3) ◽  
pp. 735-743 ◽  
Author(s):  
José Amorim Reis-Filho ◽  
Francisco Barros ◽  
José De Anchieta Cintra Da Costa Nunes ◽  
Cláudio Luis Santos Sampaio ◽  
Gabriel Barros Gonçalves De Souza
Keyword(s):  
Tidal Flat ◽  
Dominant Species ◽  
Full Moon ◽  
Diversity Indices ◽  
Tidal Range ◽  
Species Number ◽  
Trophic Groups ◽  
Significant Difference ◽  
The Mean ◽  
Tropical Tidal Flat

The influence of the lunar phases and tidal range on the fish capture was analysed in a tidal flat in Barra do Paraguaçu (Baía de Todos os Santos). The sampling was realized in the flood tide and ebb tide of the spring (full moon) and neap (waning moon) tides, between June 2007 and May 2008. At all sampling occasions, two parallel drags were accomplished to the tidal flat, in the same direction of the current, in a 100 m long area marked on the beach beforehand, using a seine net of 15 m × 2.0 m with a mesh of 12 mm between adjacent knots. A total of 2312 fish specimens were captured (26.5 kg), belonging to 75 species from 45 families. The mean number of captured fish was significantly larger in full moon at ebb tides, while the mean weight in the captures was larger in ebb tides. There was significant difference in number of species, number of fish, richness and diversity between full and waning moons. The number of fish and biomass were significantly different between tides. Significant differences were found in community structure regarding trophic groups in relation to tide and moon, although the classic diversity indices did not capture this effect between tides. Furthermore, it was possible to identify preferences of occurrence related to the change of tide in dominant species.

M2 tidal currents near the continental shelf margin in the East China Sea

1988 ◽  
Vol 21 (3-4) ◽  
pp. 431-440
Author(s):  
Toru Yamashiro ◽  
Akio Maeda ◽  
Hiroshi Ichikawa
Keyword(s):  
Continental Shelf ◽  
East China Sea ◽  
Tidal Currents ◽  
East China ◽  
The East China Sea ◽  
China Sea ◽  
Shelf Margin

scholarly journals Behaviour of REEs in a tropical estuary and adjacent continental shelf of southwest coast of India: Evidence from anomalies

2012 ◽  
Vol 121 (5) ◽  
pp. 1215-1227 ◽  
Author(s):  
P M DEEPULAL ◽  
T R GIREESH KUMAR ◽  
C H SUJATHA
Keyword(s):  
Continental Shelf ◽  
Tropical Estuary ◽  
Southwest Coast Of India ◽  
Southwest Coast

scholarly journals The Impact of Reclamation on Tidal Flat Morphological Equilibrium

2021 ◽  
Vol 8 ◽  
Author(s):  
Zehua Zhong ◽  
Zhan Hu
Keyword(s):  
Tidal Flat ◽  
Dynamic Equilibrium ◽  
Anthropogenic Activities ◽  
Wave Climate ◽  
Tidal Flats ◽  
Sediment Supply ◽  
Tidal Range ◽  
The Mean ◽  
Comprehensive Framework ◽  
The Impact

Reclamation is one of the most prominent anthropogenic activities affecting tidal flat morphology and the related ecosystem service. Two representative types of reclamation are upper-flat enclosure and lower-flat enrockment. From a historical perspective, different type of reclamation was adapted in different areas in ancient China. As previous studies on reclamation are often site-specific, the reason that leads to such a difference is unclear. The intertidal dynamic equilibrium theory (DET) provides a comprehensive framework for this quest. Here, we extend the DET with additional effects of reclamation. A model based on DET (DET-ESTMORF) was applied to investigate the impact of reclamation on tidal flats. The model was validated by comparing our results against previous records and observations. Results show that both types of reclamation induce morphological adjustment by enhancing local accretion, which upset the previous equilibrium. Specifically, upper-flat enclosure drives tidal flats into evolution toward wave dominance, whereas lower-flat enrockment causes adjustment toward tidal dominance. Next, the impact of reclamation on tidal flats in different states (prograding or retreating) was investigated. We show that both enclosure and enrockment can induce accretion despite the varying wave climate and sediment supply, with the mean accretion rate raised by 1.8 cm/year and 1.2 cm/year, respectively. However, the resulting profiles are different in shape, especially on retreating flats. Finally, we point out that tidal range and sediment supply are the potential reasons affecting the choice of reclamation types in practices.

scholarly journals Australian tidal currents – assessment of a barotropic model with an unstructured grid

2020 ◽  
Author(s):  
David A. Griffin ◽  
Mike Herzfeld ◽  
Mark Hemer
Keyword(s):  
Unstructured Grid ◽  
Tide Gauge ◽  
Major Axis ◽  
Equation Model ◽  
Tidal Currents ◽  
Tidal Range ◽  
Validation Dataset ◽  
Velocity Amplitude ◽  
Shelf Seas ◽  
Relative Errors

Abstract. While the variations of tidal range are large and fairly well known across Australia (less than 1 m near Perth but more than 14 m in King Sound), the properties of the tidal currents are not. We describe a new regional model of Australian tides and assess it against a validation dataset comprising tidal height and velocity constituents at 615 tide gauge sites and 95 current meter sites. The model is a barotropic implementation of COMPAS, an unstructured-grid primitive-equation model that is forced at the open boundaries by TPXO9v1. The Mean Absolute value of the Error (MAE) of the modelled M2 height amplitude is 9.3 cm, or 13 % of the 73 cm mean observed amplitude. The MAE of phase (11°), however, is significant, so the M2 Mean Magnitude of Vector Error (MMVE, 20 cm) is significantly greater. Results for 5 other major constituents are similar. We conclude that while the model has skill at height in all regions, there is definitely room for improvement (especially at some specific locations) before harmonic predictions based on observations are rendered obsolete. For the M2 major-axis velocity amplitude, the MAE across the 95 current meter sites, where the observed amplitude ranges from 0.1 cm s−1 to 144 cm s−1, is 6.5 cm s−1, or 20 % of the 31.7 cm s−1 observed mean. This nationwide average result is not much greater than the equivalent for height, but it conceals a larger regional variation. Relative errors on the narrow shelves of NSW and Western Australia exceed 100 %, but tidal currents are weak and negligible there compared to non-tidal currents. We show that the model has predictive value for much of the 79 % of Australia's shelf seas where tides are a major component of the total velocity variability. In descending order this includes the Bass Strait, Kimberley to Arnhem Land and Southern Great Barrier Reef regions. There is limited evidence the model is also valuable for currents in other regions across northern Australia. We plan to commence publishing unofficial tidal current predictions for chosen regions in the near future, based on both the limited number of observations, and the COMPAS model.

BASIC NUMERICAL EXPERIMENTS CONCERNING THE TIDAL CURRENTS IN THE CORAL REEF AREA

2020 ◽  
Vol 76 (2) ◽  
pp. I_1441-I_1446
Author(s):  
Atsushi MIYATAKE ◽  
Sho NAGATA ◽  
Masashi TOYOTA ◽  
Tetsuya SHINTANI
Keyword(s):  
Coral Reef ◽  
Numerical Experiments ◽  
Tidal Currents ◽  
Reef Area ◽  
Coral Reef Area
Sign in / Sign up

Export Citation Format

Share Document