Bay Environment Research Articles

Produk Pariwisata Berbasis Ekologi di Ha Long Bay, Vietnam

Ha Long Bay is one of eminent tourist destinations in Vietnam. This destination has been attaining international recognition for its landscape beauty and uniqueness, besides its geological values inside the region. There has been an increasing number on tourist arrivals since Ha Long Bay declared as UNESCO Heritage Sites in 1994. However, the increasing of tourist visitors teamed with some problematic issues related to environment and certain conflicts between tourism and protection to natural heritage. This paper discussed the issues and government efforts to manage Ha Long Bay tourist destination. Research Method used is qualitative and descriptive data analysis. Data sources derived from primary and secondary data. The result of the research shows that Vietnamese Government has issued Strategy on Vietnam’s Tourism Development until 2020, Vision to 2030 and Vietnam’s Sustainable Development Strategy for 2011-2020. Ha Long Bay Management Board becomes the leading sector in Ha Long Bay management, which has been doing partnership with international organizations, involving local government, private sectors and local communities. These become an important point for the implementation of Action Plan for Preservation of the Ha Long Bay Heritage, to achieve quality tourism and sustainability of Ha Long Bay environment.

Dispersal potential of neritic benthic foraminifera in the coastal areas of the Japanese Islands and its application to paleoenvironmental studies

In this study, we evaluated the dispersal potential of both modern and fossil benthic foraminifera in lagoon and bay environments in the Japanese Islands. Our investigations of living (stained) benthic foraminifera in Maizuru Bay (central Japan) revealed complicated lateral distributions and high temporal variation among common benthic species. Benthic foraminiferal communities in bay environments are often characterized by strong lateral trends in species richness due to frequent fluctuations in the salinity and/or dissolved oxygen content of the hypolimnion. However, our results do not show the existence of similar trends in Maizuru Bay. In fact, the dispersal of opportunistic species during intense coastal winter mixing events may account for this complexity in species diversity and evenness. Sediment trap and plankton tow observations in Lake Nakaumi (southwestern Japan) imply that benthic foraminifera utilize suspended organic matter aggregates as mobile substrates for passive dispersal. Furthermore, we examined three horizons of high fossil benthic foraminiferal abundance in the Aso-kai Lagoon (central Japan) dating to ca. AD 1070, 1400, and 1570, which were nearly coincident with coastal mixing events that were likely caused by enhanced East Asian winter monsoons. Many of the neritic benthic foraminifera in our study region appear to possess high dispersal potential, suggesting that the distribution of opportunistic benthic foraminifera may be useful in inferring the past status of the East Asian winter monsoon.

Tidal strait to embayment: Seismic stratigraphy and evolution of a rock-bounded embayment in the context of Holocene sea level change

Elongate, rock-framed Santa Catarina Island partly encloses a low-energy marine embayment that communicates with the ocean via narrow, rock-bounded inlets with ebb and flood-tide deltas. The bay shoreline consists of low-energy sandy beaches, strandplains, mangroves and bayhead deltas while the exposed Atlantic shoreline comprises a series of headland-embayment littoral cells in a linked, north-directed longshore drift system.New and previously published seismic stratigraphic investigations enable assessment of the palaeogeographic/geomorphic evolution of the area since the early Holocene. At a sea level of ca. −50 m a sandy mainland-attached shoreline complex (dune and beach) developed on a coastal plain setting some 6–7 km offshore of the present shoreline. North of the island, a barrier island and tombolo were formed in a coastal re-entrant adjacent to the northern entrance to Florianopolis Bay. The open coast beach/dune system was overstepped by rapid sea-level rise during MWP-1B whereas the barrier island and tombolo continued to accrete until MWP-1C when they too were overstepped.The back-island embayment contains up to 40 m of sediment overlying an irregular bedrock surface. It was initially flooded during MWP-1C and the early muddy sedimentation suggests a distal, sheltered marine embayment. The subsequent development of many large bioherms on bedrock and mud suggests a change to more fully marine conditions as sea-level continued to rise. In the North Bay, these were subsequently enveloped by tidal dunes migrating north from the mid-bay. The vertical stacking of 3-D and 2-D sandy bedforms suggests that a tidal strait had developed with strong tidal currents radiating from a constriction in the vicinity of modern Florianopolis City. The strong tidal currents may be linked to the Holocene sea-level high that is well documented for this region.A fall in sea level from this highstand, coupled with accumulation of tidal strait sediments, reduced the tidal prism and strength of tidal currents in the bay. At the same time, regressive beachridge plains developed in open coast and bay environments. This coincided with development of the contemporary tidal inlet complexes at the north and south outlets of the bay. As a consequence, the upper surface of the tidal strait sand deposits experienced tidal ravinement and the bay switched to a sheltered back-barrier environment dominated by deposition of mud and silt which blanket the contemporary bay floor. The tidal inlets sequestered sand from the littoral drift system in ebb and flood-tide deltas, which created breaks in the longshore drift system, causing littoral sediment to accumulate at the north of the island in a series of spits, and promoting strandplain development south of the island.

Geochemical and micropaleontological impacts caused by the 2011 Tohoku-oki tsunami in Matsushima Bay, northeastern Japan

We present stratigraphic, geochemical (CNS elemental analysis), and micropaleontological (ostracode assemblages) evidence for the 2011 Tohoku-oki tsunami impact in Matsushima Bay, northeastern Japan, and examine the recovery process after the impact to the bay environment using short sediment cores from two different topographic settings at a water depth of approximately 4 m. At both sites, tsunami deposits are composed of two sedimentary layers that recorded the first tsunami run-up and backwash. At the western site near the channel that connects the bay with the Pacific Ocean, the first tsunami wave eroded the bay floor sediments and left the tsunami deposits composed of medium sand rich in shell fragments, but with sparse numbers of meiobenthic ostracodes. By contrast, at the eastern site, which is surrounded by many small islands, the first wave eroded very little of the bay floor sediments and left tsunami deposits consisting of sandy mud, rich in exotic ostracodes, such as phytal species, shallow marine sand dwelling species, and brackish water species. Overlying post-tsunami deposits are composed mainly of organic-rich mud in which organic matter was derived primarily from marine plankton. Ostracode assemblages in the tsunami deposits lack the offshore species that live in water depths >50 m and are dominated by the species from Matsushima Bay and its adjacent nearshore, upper sublittoral areas, and brackish water environments. The distance from deep-water offshore areas to the core sites is too far to transport ostracode valves by tsunami waves.

Habitat use, seasonality and demography of an apex predator: sevengill shark Notorynchus cepedianus in northern Patagonia

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 603:147-160 (2018) - DOI: https://doi.org/10.3354/meps12715 Habitat use, seasonality and demography of an apex predator: sevengill shark Notorynchus cepedianus in northern Patagonia Alejo J. Irigoyen1,*, Agustín M. De Wysiecki1, Gastón Trobbiani1, Nelson Bovcon2, Cynthia A. Awruch1,3, Federico Argemi4, Andrés J. Jaureguizar5,6 1Centro para el Estudio de Sistemas Marinos (CESIMAR), Consejo Nacional de Investigaciones Científicas y Técnicas (CCT CENPAT-CONICET), Puerto Madryn U9120ACD, Argentina 2Departamento de Pesca Deportiva, Secretaría de Pesca de la Provincia del Chubut 9020, Argentina 3School of Natural Sciences, University of Tasmania, Hobart, Tasmania 7001, Australia 4Aquarium Fundación Temaiken, Buenos Aires 1625, Argentina 5Comisión de Investigaciones Científicas de la Provincia de Buenos Aires (CIC), La Plata 1900, Argentina 6Instituto Nacional de Investigación y Desarrollo Pesquero (INIDEP), Mar del Plata B7600EEP, Argentina *Corresponding author: alejo@cenpat-conicet.gob.ar ABSTRACT: Gaining insight on how species relate to their environment and other members of the trophic community is critical for their management. We investigated habitat use, seasonal patterns of abundance and population structure of the broadnose sevengill shark Notorynchus cepedianus in the marine temperate environment of a northern Patagonian bay (Argentina). We expected N. cepedianus to exhibit strong seasonality in the bay driven by the seasonal occurrence of important marine mammal prey. However, an alternative or complementary hypothesis arose from the possibility that N. cepedianus uses the area seasonally as mating grounds. To explore these hypotheses, a suite of baited remote underwater video stations and catch per unit effort data indices were used to estimate the seasonal relative abundance of the species inside the bay. Reproductive hormone levels were measured to determine reproductive status and maturity stages of the population. Results indicated that N. cepedianus uses the bay year-round, showing a peak abundance during spring when individuals aggregate, likely for feeding and mating purposes. Male and female total lengths at maturity were 170 and 190 cm, respectively. Contrary to other studies in the Southwest Atlantic, population composition remained similar throughout the seasons, with adults dominating over juveniles, and adult females prevailing in the population at all times. Considering the historical abundance decline recently reported for the species, protection and enforcement within protected areas across the Southwest Atlantic must remain of high priority in government initiatives. KEY WORDS: Baited remote underwater video station · BRUVS · Catch per unit effort · CPUE · Reproductive hormones · Seasonal occurrence · Caleta Valdés · Southwest Atlantic Full text in pdf format PreviousNextCite this article as: Irigoyen AJ, De Wysiecki AM, Trobbiani G, Bovcon N, Awruch CA, Argemi F, Jaureguizar AJ (2018) Habitat use, seasonality and demography of an apex predator: sevengill shark Notorynchus cepedianus in northern Patagonia. Mar Ecol Prog Ser 603:147-160. https://doi.org/10.3354/meps12715 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 603. Online publication date: September 17, 2018 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2018 Inter-Research.

Heavy Metal Pollution Characteristics in the Modern Sedimentary Environment of Northern Jiaozhou Bay, China.

The particle size distribution characteristics of sediments and the concentrations of heavy metals in Jiaozhou Bay were investigated in this study. The average concentrations of Cu, Pb, Zn, Cr, Cd, Hg and As were 36.88, 29.60, 82.08, 77.48, 0.083, 0.048 and 11.00mg/kg, respectively. The heavy metal concentrations were highest in the eastern sediments, followed by those at the top of the bay, and the lowest concentrations were observed in the central region. Overall, a decreasing trend from the center of the bay to the periphery was observed. Additionally, the distribution of heavy metals in sediments was not completely controlled by sediment particle size. The degree of heavy metal contamination was evaluated using the geoaccumulation index and Hakanson's method. The results revealed that the level of heavy metal pollution in the sediments was relatively low and that the main pollution elements were Cu and Hg. In addition, the sediments are associated with various levels of potential ecological risk due to the high pollution levels of Hg and Cd.

Quantification of Swell Energy and Its Impact on Wetlands in a Deltaic Estuary

The extensive coastal wetlands in Mississippi River Delta represent the seventh largest deltaic floodplain in the world, contributing to many services that sustain the economies of the region. Subsidence, sea level rise, saltwater intrusion, wave action from storms, and sediment depletion have contributed to chronic wetland losses, converting vegetated lands into open waters and increasing wind fetch. Among these factors listed, wave energy plays the largest role in marsh edge erosion in an open bay environment. Degrading barrier islands along the shoreline of this delta allow swell energy to enter protected bay areas, contributing to marsh edge erosion. Locally generated wind waves within enlarged bays also contribute to wetland loss. Quantifying the roles of swell and wind waves in marsh edge erosion is essential to any ecosystem restoration design. In this study, a numerical model is implemented to describe the wave climate of combined swell and wind waves in a deltaic estuary. Terrebonne Bay was chosen as the study area because it has experienced one of the largest reductions in barrier islands and wetland loss rates among Louisiana estuaries. A continuous wave measurement in upper Terrebonne Bay was obtained over the course of a year. A spectral wave model is used to hindcast the wave climate in the estuary. The model results are compared against the in situ wave measurement. The wave power is partitioned into swell and wind sea at different locations in Terrebonne Bay using the model results. An extensive analysis on a valid effective wave power range that directly impacts the marsh edge is performed and presented. Insight into the temporal and spatial variability of wave power is gained. Through differentiating swell and wind sea energies around the bay, improvements of long-term wave power computation for shoreline retreat prediction are made. It is found that the swell energy becomes the primary driver of marsh edge retreat in the southwest part of Terrebonne Bay as the barrier islands are degrading.

The Need for Integrated Cybersecurity and Safety Training

Companies involved in the nuclear energy domain, like component and platform manufacturers, system integrators, and utilities, have well-established yearly trainings on Nuclear Safety Culture. These trainings are typically covered as part of the annual quality assurance-related refresher trainings, introductory courses for new employees, or indoctrinations of temporary staff. Gradually, security awareness trainings are also addressed on a regular basis, typically with a focus on information technology, the daily office work, test bay, or construction site work environment, and some data protection and privacy-related topics. Due to emerging national nuclear regulation, steadily but surely, specialized cybersecurity trainings are foreseen for integrators and utilities. Beyond these safety, physical security and cybersecurity specific trainings, there is a need to address the joint part of these disciplines, starting from the planning phase of a new nuclear power plant (NPP). The engineers working on safety, physical protection, and cybersecurity must be aware of these interrelations to jointly elaborate a robust instrumentation and control architecture (defense-in-depth, design basis events, functional categorization and systems classification) and a resilient security architecture (security by design, security grading, zone model or infrastructure domain, security conduits, forensic readiness, security information, and event management). This paper provides more in-depth justification of when and where additional training is needed, due to the ubiquitous deployment of digital technology in new NPPs. Additionally, for existing NPPs, the benefits of conveying knowledge by training on specific interfaces between the involved disciplines will be discussed. Furthermore, the paper will address the need of focused training of management stakeholders, as eventually, they must agree on the residual risk. The decision-makers are in charge of facilitating the interdisciplinary cooperation in parallel to the allocation of resources, e.g., on security certifications of products, extended modeling-based safety and security analyses and security testing coverage.

Intensive anthropogenic activities had affected Daya Bay in South China Sea since the 1980s: Evidence from heavy metal contaminations

Sediment geochemical characteristics were analyzed to assess how anthropogenic activities affected the Daya Bay, a subtropics bay adjacent to the most economically developed region of China. Vertical profiles of heavy metal contents and their enrichment factors indicated the development of Daya Bay environment in the past 100 years basically experienced three stages, which were closely consistent with the economic development. Before 1980s, the concentration of heavy metals was basically at the background level. Contamination of metals, particularly for Cr, Ni, Cu, Zn, Cd, and Pb, generally began in mid-1980s and became serious in 2000s. However, after late-2000s, the sediment quality had been radically improved. Heavy metals in nearshore sediment of Daya Bay were all closely related with import of anthropogenic and/or terrestrial material, whereas those in offshore were likely to be related with joint influence from the anthropogenic activities and the natural processes.

Are early plants significant as paleogeographic indicators of past coastlines? Insights from the taphonomy and sedimentology of a Devonian taphoflora of Paraná Basin, Brazil

The continental colonization process by plants is an underexplored theme in Brazil, especially concerning taphonomic studies of plants that existed during this age. This study aims to interpret the taphonomic and paleoenvironmental settings that best represent the fossil plant assemblages preserved in the upper strata of the Furnas Formation (Lower Devonian of Paraná Basin), at Jackson de Figueiredo county, municipality of Jaguariaíva (Paraná), clarifying the potential of these fossil plant assemblages for paleogeographic reconstructions. Taphonomic and sedimentological signatures were analyzed and submitted to multivariate statistical analyses (cluster and correspondence analyses). Two taphonomic groups were identified (Taphofacies A and B). The interpretation of the two groups allowed the visualization of: Taphofacies A, which consists of samples with a dispersed degree of packing, fragmented plant fossils, 40% mica with sizes between 0.5 and 1 mm and no trace fossils, is representative of relatively high-energy conditions; and Taphofacies B, which consists of densely packed plants with partial degree of fragmentation, 10% mica with sizes under 0.5 mm and both horizontal and vertical trace fossils, is representative of relatively low-energy conditions. Our taphonomic data are consistent with previous facies interpretations of a lagoon/interdistributary bay environment. In this context, taphofacies A represents episodic sedimentation events influenced by fluvial dynamics, yielding assemblages that are not suitable for paleogeographic interpretations, while Taphofacies B represents fossil assemblages originated in a low-energy sedimentary regime, with utility for paleogeographic reconstructions.

Collective action, state building, and the rise of the Calusa, southwest Florida, USA

Our work at Mound Key, the Capital of the Calusa Kingdom, identifies a large structure on top of Mound 1 that likely was associated with a powerful long-lived lineage. The rise to power for this group coincided with a significant amelioration of the shallow-water estuarine environment of Estero Bay during the Warm Medieval Period. We interpret this commitment to place as a way for successive members of this lineage to transmit political and social capital. We propose that prior to the sixteenth century the Calusa, and the broader landscape these groups inhabited, were organized much like the great houses were at the community level. A series of small polities participated in a fluctuating heterarchical system, that were likely the result of political jockeying of high ranking houses at larger settlements. We argue that long-lived houses with their accrued political and social capital were in the best position to take advantage of events that afforded the differential exercise of agency among their peers, allowing for new, novel, and seemingly more complex engagements. We use this case study to examine the role of collective action for the development of the Calusa Kingdom observed by the Spanish explorers during the sixteenth century, and its broader comparative lessons for state building among similarly organized societies.

Ecosystem modeling as a framework to convert a multi-disciplinary research approach into a useful model for the Araçá Bay (Brazil)

A model-oriented research project can organize and systematize high quality sampling information and convert observed values into information needed to parameterize ecological models. In this paper, we describe the value parameterization process from an interdisciplinary project to the development of a food web model (using Ecopath) in order to comprehend the Araçá Bay ecosystem structure (Brazil) and to forecast the impact of a port expansion (São Sebastião Port) over a bay environment. Araçá Bay Ecopath model has 34 compartments, Phytoplankton, Phytobenthos, Mangrove, Zooplankton, 10 groups of benthos, 13 fish groups, Shrimp, Crabs, Turtles, two bird groups and two groups of Detritus. The model outputs showed that Araçá Bay is a mature and detritus-based ecosystem. It is highly influenced by the role of benthos groups which are responsible for a huge amount of detritus recycling due to their large biomass value. The simulation of port expansion (primary producers' reduction), using the Ecosim module, indicated negative impacts on almost all living groups and an increase in detritus accumulation, leading the entire bay ecosystem towards its collapse (in the short term). The interdisciplinary organized sampling process presented here is an example of how objectively planned sample design and modeling may guide scientists, local people and stakeholders' decisions with valuable integrated information and overall predictions in order to consider the sustainable use of natural areas and resources.

Mechanism of Organic Matter Accumulation in Residual Bay Environments: The Early Cretaceous Qiangtang Basin, Tibet

The controlling mechanisms for the accumulation and preservation of organic matter in residual bay environments during the transition from marine to continental settings are not well understood, although oil–gas source rocks can form in this setting. In this study, we develop a case study for the Early Cretaceous black rock series in the northern Qiangtang Basin, Tibet (i.e., the Upper Member of the Suowa Formation), by conducting a combined organic and inorganic geochemical analysis of micritic limestone, marl, and shale samples from an outcrop section. Results show that total organic carbon (TOC) contents of the studied samples are between 1.74% and 7.71%, with the organic matter being Type II/III kerogen. Of the three factors that could influence the observed TOCs and organic matter types, including paleoproductivity, preservational environment, and sedimentation rate, the preservational environment appears to be the dominant factor, independent of lithology. This is typically supported by the relative...

Distribution patterns and population dynamics of the pandalid shrimp Plesionika izumiae (Decapoda, Caridea) in a unique semi-enclosed deep-water bay environment

Abstract The pandalid shrimp Plesionika izumiae Omori, 1971 has a wide bathymetric distribution in the coastal waters and the upper continental slope of west Pacific regions. The distribution patterns and population dynamics of P. izumiae were studied in a unique semi-enclosed deep-water bay, Kagoshima Bay, southern Japan, with very steep slopes on both sides. Plesionika izumiae shows a wide spatial distribution in the bay with the majority of the individuals inhabiting the channel area with sediments of almost equal portions of silt and sand, as well as in the bay head with a silty sediment. There were no significant relationships between bottom water temperature or salinity and the distribution patterns of this shrimp, but the sediment characteristics and water depth might appear to influence the distribution patterns of P. izumiae. The distribution patterns with progression of age reveal the dynamics of the P. izumiae population, which was studied by selecting one cohort from each sex and tracing them throughout their life cycle, resulting in similar patterns being shown for both sexes. Juveniles (at the age of 5.7 months) occurred throughout the distribution areas; however, there was a low catch per unit effort (CPUE) even in the main spawning grounds, probably from due to the ongoing recruitment process. The substantial increment in CPUE at the age of 8.4 months throughout the distribution areas likely indicate the stock to be fully recruited by then. A clear shift in CPUE of these cohorts was observed at the ages of 11.6 months and 14.3 months, from the deeper areas towards the shallower areas of the bay, possibly suggesting spawning migration. Individuals approaching their maximum size and longevity were found mostly in the deeper waters. A marked seasonal pattern in CPUE was noted with higher values recorded in summer and lower in winter, which could possibly be related to the life history of the shrimp.

Paleolimnology of a freshwater estuary to inform Area of Concern nutrient delisting efforts

The St. Louis River Estuary (SLRE), a freshwater estuary bordering Duluth, Minnesota, Superior, Wisconsin, and the most western point of Lake Superior (46.74°, − 92.13°), has a long history of human development since Euro-American settlement ~ 200 years ago. Due to degradation from logging, hydrologic modification, industrial practices, and untreated sewage, the SLRE was designated an Area of Concern in 1987. Action has been taken to restore water quality including the installation of the Western Lake Superior Sanitary District in 1978 to help remove beneficial use impairments. A better understanding of historical impacts and remediation is necessary to help document progress and knowledge gaps related to water quality, so a paleolimnological study of the SLRE was initiated. Various paleolimnological indicators (pigments, diatom communities, and diatom-inferred phosphorus) were analyzed from six cores taken throughout the SLRE and another from western Lake Superior. Reductions in eutrophic diatom taxa such as Cyclotella meneghiniana and Stephanodiscus after 1970 in certain cores suggest an improvement in water quality over the last 40 years. However, in cores taken from estuarine bay environments, persistence of eutrophic taxa such as Cyclostephanos dubius and Stephanodiscus binderanus indicate ongoing nutrient problems. Sedimentary pigments also indicate cyanobacteria increases in bays over the last two decades. Diatom model-inferred phosphorus and contemporary monitoring data suggest some of the problems associated with excess nutrient loads have been remediated, but modern conditions (internal phosphorus loading, changing climate) may be contributing to ongoing water quality impairments in some locations. The integrated record of biological, chemical, and physical indicators preserved in the sediments will aid state and federal agencies in determining where to target their resources.

TELUK CENGAL : LOKASI PELABUHAN SRIWIJAYA?

Archaeological researches in southeast coast of Sumatra find archaeological prove of Srivijaya era (7-13 AD). Settlement sites located along tidal swamp rivers near shoreline. Srivijaya communities lived on house on stilts from wood on the wetlands. The artifacts came from aboard, eg. Chinese ceramics, beads from India and glasses from Persian found with local artifacts. Also found boats of Southeast Asia tradition use sewn plank and lashed-lug technique. These artifacts represent maritime activities in southeast coast of Sumatra. Estimated southeast coast of Sumatra, which facing Strait of Bangka, is an archaeological settlement area of Srivijaya and also pre Srivijaya periods. This one have the harbour and the port. This paper tried to identify one of the archaeological settlement area which estimated as an entreport of Srivijaya period. This area located in Bay of Cengal, District of Ogan Komering Ilir, Province of South Sumatra. Remains of activity area concentrated in Lumpur River basin and empties into Java Sea. Identification an archaeological settlement area in Bay of Cengal based on archeological data analysis, textual and maps resources, environment and position of Bay of Cengal in global maritime networks of SrivijayaPenelitian arkeologi di pesisir tenggara Sumatra menemukan bukti-bukti arkeologis yang sezaman dengan berkembangnya Sriwijaya di Sumatra (7-13 M). Situs-situs hunian mengelompok di tepi aliran sungai rawa pasang surut. Situs-situs tersebut berada di hilir sungai yang lokasinya relatif dekat dengan garis pantai sekarang. Penduduk masa Sriwijaya tinggal pada rumah-rumah panggung bertiang kayu di lahan basah. Artefak-artefak yang ditemukan sebagian besar berasal dari luar negeri, seperti keramik Cina, manik-manik dari India dan kaca-kaca dari Persia dijumpai bersama dengan barang-barang lokal, seperti barang-barang dari tembikar. Ditemukan pula perahu-perahu kuna tipe Asia Tenggara berupa perahu kayu yang dibuat dengan teknik papan ikat (sewn plank) dengan menggunakan tali ijuk dan juga menggunakan pasak kayu. Bukti-bukti arkeologis tersebut menunjukan adanya aktivitas kemaritiman di pantai tenggara Sumatra. Diperkirakan pantai tenggara Sumatra yang berhadapan dengan Selat Bangka dan Laut Jawa merupakan kawasan okupasi masa Sriwijaya dan masa sebelumnya yang dilengkapi bandar pelabuhan. Tulisan ini berupaya mengidentifikasi salah satu kawasan situs di pantai tenggara Sumatra yang diperkirakan sebagai permukiman dan bandar pelabuhan masa Sriwijaya. Kawasan itu berada di Teluk Cengal yang terdapat di pantai timur Kabupaten Ogan Komering Ilir, Provinsi Sumatera Selatan. Tinggalan arkeologis terkosentrasi di daerah aliran Sungai Lumpur yang bermuara di Laut Jawa. Upaya mengidentifikasi kawasan situs di Teluk Cengal dilakukan berdasarkan analisis data arkeologi, sumber tertulis dan peta, keadaan lingkungan dan posisi Teluk Cengal dalam jaringan pelayaran maritim global masa Sriwijaya

Microfossil evidence for recurrent coseismic subsidence around Lake Hamana, near the Nankai-Suruga trough, central Japan

We reconstructed recurrent coseismic subsidence during the middle Holocene from analyses of sedimentary facies and fossil diatom assemblages in a small drowned valley, the Shinjo lowland, bordering Lake Hamana, near the Nankai–Suruga trough, central Japan. The Lake Hamana region is known for coseismic subsidence during the 1707 Hoei (M8.6) and 1854 Ansei-Tokai (M8.4) earthquakes along the Nankai–Suruga trough subduction zone.A coring survey revealed three widely distributed peat layers in the lowland, with a mud layer overlying each of the two lower peats with a sharp contact. We traced the alternating peat–mud beds for over 300 m along the long axis of a valley. The fossil diatom assemblage analysis revealed that the peat layers were deposited in a freshwater pond/marsh environment, which changed abruptly to an estuarine to inner bay environment, recorded by the mud layers. From the sudden environmental change at the two peat–mud contacts and our radiocarbon dating results, we inferred that coseismic subsidence followed by an invasion of seawater into the lowland occurred at least twice, during a great earthquake that occurred between 5645 and 6635 cal yr BP and during another great earthquake at ca. 5700 cal yr BP.Within the mud layers, the dominant diatom species changed gradually upward from Nitzschia frustulum and Cocconeis scutellum in the lower part to Cyclotella striata and Achnanthes submarina in the upper part. These changes suggest that water depth and salinity gradually increased after the coseismic subsidence. A possible cause of this gradual subsidence is postseismic subsidence following great Nankai-Suruga trough earthquakes.

The genetic structure of a marine teleost, Chrysophrys auratus, in a large, heterogeneous marine embayment

There is considerable interest in the processes that generate genetic divergence in marine species and the spatial and temporal scales over which these processes operate. Shark Bay, a large embayment (~13,000 km2) on the arid west coast of Australia, has been described as a focal point for genetic divergence in marine species due to its heterogeneous environment. This study represents the first DNA-based analysis of the genetic structure of a marine species with pelagic early life stages (ELS) in this region. Twelve microsatellite loci were used to compare the genetic composition of the teleost Chrysophrys auratus from five areas within Shark Bay, and from near-by shelf waters approximately 250 km to the south. The results suggest that the microsatellite composition of C. auratus is homogeneous across most of Shark Bay and near-by shelf waters. This genetic homogeneity is probably maintained via small amounts of contemporary gene flow, which may reduce the potential for C. auratus to locally adapt to the Shark Bay environment. A weakly differentiated assemblage in Freycinet Estuary in the Western Gulf of Shark Bay provided an important exception to the otherwise homogeneous microsatellite composition of C. auratus in the study area. This weak differentiation probably reflects restrictions to gene flow into and/or out of this site due to the temporal isolation of breeding adults, selective mortality of immigrants and/or the presence of hydrological barriers to larval transport. Each of these factors can be linked to environmental heterogeneity in Shark Bay.

Petrographic Characteristics and Depositional Environment Evolution of Middle Miocene Sediments in the Thien Ung - Mang Cau Structure of Nam Con Son Basin

DOI: 10.17014/ijog.4.3.143-157This paper introduces the petrographic characteristics and depositional environment of Middle Miocene rocks of the Thien Ung - Mang Cau structure in the central area of Nam Con Son Basin based on the results of analyzing thin sections and structural characteristics of core samples. Middle Miocene sedimentary rocks in the studied area can be divided into three groups: (1) Group of terrigenous rocks comprising greywacke sandstone, arkosic sandstone, lithic-quartz sandstone, greywacke-lithic sandstone, oligomictic siltstone, and bitumenous claystone; (2) Group of carbonate rocks comprising dolomitic limestone and bituminous limestone; (3) Mixed group comprising calcareous sandstone, calcarinate sandstone, arenaceous limestone, calcareous claystone, calcareous silty claystone, dolomitic limestone containing silt, and bitumen. The depositional environment is expressed through petrographic characteristics and structure of the sedimentary rocks in core samples. The greywacke and arkosic sandstones are of medium grain size, poor sorting and roundness, and siliceous cement characterizing the alluvial and estuarine fan environment expressed by massive structure of core samples. The mixed calcareous limestone, arenaceous dolomitic limestone, and calcareous and bituminous clayey siltstone in the core samples are of turbulent flow structure characterizing shallow bay environment with the action of bottom currents. The dolomitic limestones are of relatively homogeneous, of microgranular and fine-granular texture, precipitated in a weakly reducing, semi-closed, and relatively calm bay environment.

Potential Salinity and Temperature Futures for the Chesapeake Bay Using a Statistical Downscaling Spatial Disaggregation Framework

Estuaries are productive and ecologically important ecosystems, incorporating environmental drivers from watersheds, rivers, and the coastal ocean. Climate change has potential to modify the physical properties of estuaries, with impacts on resident organisms. However, projections from general circulation models (GCMs) are generally too coarse to resolve important estuarine processes. Here, we statistically downscaled near-surface air temperature and precipitation projections to the scale of the Chesapeake Bay watershed and estuary. These variables were linked to Susquehanna River streamflow using a water balance model and finally to spatially resolved Chesapeake Bay surface temperature and salinity using statistical model trees. The low computational cost of this approach allowed rapid assessment of projected changes from four GCMs spanning a range of potential futures under a high CO2 emission scenario, for four different downscaling methods. Choice of GCM contributed strongly to the spread in projections, but choice of downscaling method was also influential in the warmest models. Models projected a ~2–5.5 °C increase in surface water temperatures in the Chesapeake Bay by the end of the century. Projections of salinity were more uncertain and spatially complex. Models showing increases in winter-spring streamflow generated freshening in the Upper Bay and tributaries, while models with decreased streamflow produced salinity increases. Changes to the Chesapeake Bay environment have implications for fish and invertebrate habitats, as well as migration, spawning phenology, recruitment, and occurrence of pathogens. Our results underline a potentially expanded role of statistical downscaling to complement dynamical approaches in assessing climate change impacts in dynamically challenging estuaries.