Dapeng Bay Research Articles

Spatial and temporal variabilities of coastal nekton community structure and phylogenetic diversity in Daya and Dapeng Bay, southern China

Coastal areas are important habitats for many species and strongly affected by anthropogenic activities. Management for sustainable coastal ecosystems benefits from a comprehensive assessment of species diversity. Here, we measured the spatio-temporal changes in community and phylogenetic structure of spring and autumn nektonic communities in Daya and Dapeng Bay among 12 sampling sites. We found that both the community structure and phylogenetic facets of nektonic communities in Daya and Dapeng Bay exhibited strong spatial and temporal patterns due which we attribute to fishing intensity and mid-summer fishing moratorium. The relatively larger ratio of unexplained variation in the autumn community resulted from stochastic processes caused by the mid-summer fishing moratorium. Furthermore, the phylogenetic structure of the spring nektonic communities between Dapeng and Daya Bay were significantly different; obvious phylogenetic clustering was found in spring nektonic communities of Dapeng Bay. These results implied that we may consider the current fishing intensity as a strong stress for nektonic communities, which exceeds the effect of natural processes and environmental factors. We speculate that the immediate sweeping fishing efforts may rapidly deplete the recovered fish stocks in a short time as human activities exert great stress on the nektonic communities in the study area. To avoid permanent damage to the ecosystem and a loss of valuable marine resources, urgent attention is required for fishery management.

Mercury distribution and speciation in two lagoons with different pollution and eutrophication conditions in Taiwan

This study explored biogeochemical processes controlling the distribution of mercury (Hg) species in two lagoons with different pollution and eutrophication conditions in southwestern Taiwan. The eutrophication and pollution levels were higher in the Dapeng Bay than in the Chiku Lagoon, engendering a higher particulate Hg concentration and enrichment factor in the Dapeng Bay. The concentration range of total dissolved Hg (HgTD) and reactive Hg (HgR) was comparable between the lagoons, but the concentration of particulate Hg (HgP) was higher in the Dapeng Bay. HgR and HgTD abundance was primarily controlled by the availability of dissolved oxygen (DO) and biological absorption. In addition to pollution (which elevated HgP concentration), biological absorption and/or adsorption rather than lithogenic processes more likely regulated the HgP concentration. The effect of Hg pollution may superimpose on that of DO on the distributions of HgR and HgTD and may enhance HgP formation in the Dapeng Bay.

Impacts of Thermal Discharge on Phytoplankton in Daya Bay

ABSTRACT Ye, Y.; Chen, K.; Zhou, Q.; Xiang, P.; Huo, Y., and Lin, M., 2018. Impacts of thermal discharge on phytoplankton in Daya Bay. In: Liu, Z.L. and Mi, C. (eds.), Advances in Sustainable Port and Ocean Engineering. Journal of Coastal Research, Special Issue No. 83, pp. 135–147. Coconut Creek (Florida), ISSN 0749-0208. A monthly survey on the species composition of phytoplankton was conducted at 14 stations in Yaling Bay, Dapeng Bay and the mouth of Daya Bay in 2016, and 4 stations were selected as main sections to analyze the effects of thermal discharge on the phytoplankton community structure. In this study, the 12 months in 2016 were divided into the high temperature period and the low temperature period with 25°C as the boundary. The results suggested that the response of phytoplankton to elevated water temperature was significantly different during different periods: during the high temperature period, algae proliferated, among which diatom was the dominant species; during the low temperature pe...

Characteristics of Nutrients and Eutrophication Assessment of Shenzhen Offshore Waters

Based on the data obtained in the coastal waters of Shenzhen from the Guangdong Environmental Monitoring Center,the distribution of DIN, DIP were analyzed, and the temporal spatial variations of nutrient level and organic pollution situation were evaluated using methods such as single factor index, eutrophication index,and water organic pollution evaluation index. The results show that the nutrient level of the eastern waters was lower than that of the western. The Dapeng Bay and Daya Bay comply with the first-class seawater standard, the Zhujiang Estuary and Shenzhen Bay exceed the fourth-class seawater standard. And there were some similarities between the eutrophication and organic pollution spatial distribution, and the eutrophication and organic pollution were observed in the western waters. The correlation analysis suggested there was a negatively correlation between salinity and major pollutants (P<0.01), implying the relationship between terrigenous pollution and the content of environmental elements.

An assessment of wind and wave climate as potential sources of renewable energy in the nearshore Shenzhen coastal zone of the South China Sea

In this study, nearshore wind and wave climates and their potential as renewable energy sources are evaluated by means of buoy observational data for the Shenzhen coastal region. Six buoys were originally deployed in the region by the city local government of China in 2014, and are located in different areas of the study region, including Dapeng Bay, Daya Bay, Shenzhen Bay. The waters in these areas are relatively shallow, ranging in depth between about 3 and 22 m. The results show that during 2014–2016, annual mean wind speeds (at 2.5 m above the sea surface) in the region varied between 3.1 and 4.1 m s−1, leading to wind powers between 37 and 94 W m−2; significant wave heights were mostly less than 1 m, while wave energy periods were mostly in the range 3− 7 s. As a result, wave power was mostly less than 1.0 kW m−1. It is concluded that the potential of wave energy as a renewable resource at the buoy locations was very small. This may be due to the fact that, first, water depth is very shallow, and, secondly, the buoys are located in bays where the sea is somewhat semi-enclosed, all of which are not favorable for the development of wind waves.

GLM-Based Analysis on Seasonal Variation of Fishery Resources in Dapeng Bay, China

Dapeng Bay is a typical offshore fisheries area in the South China Sea (SCS). In order to understand the fishery resources, seasonal variations of species composition, dominant species composition, standardized catch per unit effort (SCPUE) and community diversity of fishery resources in Dapeng Bay, China were analyzed based on trawl survey data in spring (March) and summer (May) of 2013 as well as autumn (August) and winter (December) of 2012. Results demonstrated that there are 113 fishery species, which belong to 78 categories, 50 families, 14 catalogues, 3 classes. There are the most species in summer (61 species) and about 56 species in other seasons. In all four seasons, fish and crustacea are dominant species, and there are the fewest cephalopoda. High values of SCPUE occur in spring and autumn, reaching 5.65 and 5.33, respectively. SCPUE is generally low in summer, ranging between 0.52 - 0.96. Fish biodiversity is the highest in summer and the lowest in winter. Among biodiversity, Shannon-Wiener diversity index, Margalef diversity index and Pielou evenness index vary in the same trend. They are decreasing from summer, spring, autumn to winter successively. Therefore, there are violent seasonal variation of species composition, quantity and structure of fishery resources in Dapeng Bay. The community structure and function are highly stable in summer, but they have poor stability in autumn and winter. This research can provide scientific references for protection and sustainable use of fishery resources in typical offshore fisheries area in the SCS.

The Impact of Typhoon Morakot on Heavy Metals of Dapeng Bay and Pollution from Neighboring Rivers

This study demonstrates that prior to Typhoon Morakot, the index of heavy metals such as Cd, Pb, and Cr was above moderate pollution levels in Dapeng Bay and the three neighboring rivers. During January 2007, the content of Zn metal in Dapeng Bay and Tungkang River was also above moderate pollution levels, while after the Typhoon Morakot event, all metals were at levels below the criteria for low pollution. This work has demonstrated that the samples collected from Dapeng Bay and the three neighboring river systems displayed individual crowd–distribution phenomena, indicating variability between the heavy metal content of sediments collected from Dapeng Bay and the three neighboring rivers. Understanding the spatial and temporal variability of heavy metal pollutants in the sediments of Dapeng Bay, along with pollution sources from three neighboring rivers, provides useful information in the fields of disaster management, habitat recovery, operative management, as well as ecotourism specification.

Comprehensive assessment of coastal eutrophication in Taiwan and its implications for management strategy

Due to the rapid population growth, anthropogenic activities result in agricultural, industrial, and urban diffuse runoffs that elevate the level of nutrients such as nitrogen and phosphorus in coastal waters. Currently there is no integrated analysis for coastal eutrophication in Taiwan. A comprehensive analysis of the coastal eutrophic status was performed in this study based on decade-long coastal water quality monitoring data from Taiwan’s Environmental Protection Administration. A 3-tiered monitoring strategy is recommended based on the severity of the current eutrophication state. Results indicate that the most problematic area of coastal eutrophication is located in the estuary of the Donggang River (DGR) and its adjacent coastal waters, i.e., the Kao-Ping mouth (KPM) and Dapeng Bay (DPB) in south-western Taiwan. With a worsening eutrophic status, these areas demand intensive monitoring and research with higher spatial and temporal resolutions to evaluate the stresses of nutrient forcing and predict possible future responses.

Seasonal Variations of Heavy Metals Content in Muscle and Viscera of Green-Lipped Mussel Perna viridis From Da-Peng Bay Lagoon in Taiwan

As a natural lagoon, rich in biological resources including fish, crabs, and bivalves, Da-Peng Bay Lagoon receives the discharges from the neighboring rivers, Kao-ping, Dong-gang, and Lin-Bian, which have harmed the ecology and reduced the water quality of the lagoon. This study analyzes seasonal variation of heavy metals concentration (As, Cd, Cr, Cu, Hg, Ni, Pb, and Zn) in the muscle and viscera of the green-lipped mussel Perna viridis from Da-Peng Bay Lagoon. Data from this study may provide information on the use of Perna viridis as a bioindicator for heavy metals pollution in the lagoon. The heavy metals concentrations were greater in viscera than in muscles of the green-lipped mussel Perna viridis. Results showed that the mussel is capable of accumulating high contents of Cu and Zn. Generally, the order of concentrations in the muscle by season was Zn > Cu > Cr or As. In viscera, the general order of concentrations was Zn > Cu > Pb or Cr or As. Mercury was not detected in winter and spring in muscle and viscera. Cadmium displayed significant variation with season. There was also significant correlation between tissue concentration and heavy metals, including Cu, Pb, Zn, Ni, Cd, and As.

Spatio-temporal comparisons of imposex status and tissue organotin concentration in the whelk Reishia clavigera collected along the coasts of Dapeng Bay and Daya Bay, Shenzhen, China

Organotin compounds (OTs) have caused widespread adverse effects on marine organisms. As no local restrictions on OT-based antifouling paints have been implemented in China, high concentrations of OTs still occur in coastal environments. In this study, we measured the imposex status and tissue concentrations of OTs in the whelk Reishia clavigera collected along the coast of Dapeng Bay and Daya Bay of Shenzhen, China in 2013. Our results showed that all female whelks suffered from the onset of imposex. The highest concentration of total OTs was 27,756μgkg−1 dry weight in the samples collected from Shuitousha. Triphenyltin was the most predominant residue, accounting for more than 97.8% of total OTs across all sites. Compared with the results from previous studies, the marine environment of this region is still heavily contaminated with OTs. Therefore, a tightened control is necessary to regulate the use and release of OTs in China.

Heavy Metals in Bivalve Mollusks Collected From Da-Peng Bay Lagoon in South-Southwestern Taiwan

In this study, concentrations of several heavy metals (Cu, Pb, Zn, Ni, Cr, and Cd) were measured in Katelysia hiantina, Anomalocardia squamosa, Perna viridis, Anadara antiquata, Paphia undulata, and Sanguinolaria diphos bivalve mollusks from Da-Peng Bay Lagoon near the south-southwestern coast of Taiwan. The metal pollution index (MPI) values were highest and lowest in winter and autumn, respectively. The MPI value in the viscera of P. viridis was higher than in muscles. In all four seasons, Zn concentrations in viscera and muscles of P. viridis were higher than for other metals. The capacities of A. squamosa to accumulate the concentrations of Cu, Ni, and Cr and of A. antiquata to accumulate concentrations of Pb, Zn, and Cd were significant. Analytical results suggested that A. squamosa and A. antiquata may be used as bioindicators for monitoring Cu, Ni, Cr, Pb, Zn, and Cd heavy-metal pollution in Da-Peng Bay Lagoon throughout the year.

Mercury profiles in surface sediments from ten bays along the coast of Southern China

Spatial and temporal variations of mercury (Hg) were investigated from ten representative bays along the coast of Southern China. The total Hg (THg) in surface sediments varied widely with concentrations from 25 to 264ng/g. As a whole, Hg pollution in several bays occupied by busy sea traffic and industrial activities, such as Shantou (ST) Bay and Dapeng (DP) Bay were remarkably more serious than others, which reflected the direct effects of anthropogenic activities around the coastal areas. Hg variations in sediment cores clearly display upcore rising trend which obviously correlates with the trend of economic development and urbanization in the last five decades. No significant correlations were found between Hg and organic matter and particle size, suggesting that the distribution of Hg is not fully controlled by these variables.

Spatial and Temporal Variation on Heavy Metals in the Sediments of Dapeng Bay and Neighboring Rivers

The Typhoon Morakot raged through Taiwan bringing torrential rain for two days, which led to debris-flow in mountains and severe flooding in the coastal areas of southern Taiwan. In order to realize the impact of the Typhoon Morakot on heavy metals in the sediments this research discriminate the pollution brought from three neighboring rivers to the Dapeng Bay lagoon by using the R. A. Fisher Method. The results generally indicate that the samples from Dapeng Bay and the three neighboring rivers are displaying individual crowd-distribution phenomena, which means that the heavy metal content in the sediments of Dapeng Bay and the three neighboring rivers are not totally similar. Today, due to a massive variation in eco-habitat and a more frequently changing climate, the understanding of spatial-temporal variation of heavy metal pollution of sediments in Dapeng Bay and pollution sources from three neighboring rivers will provide useful information regarding disaster management, habitat recovery, operative management, as well as ecotourism specification.

Efficiencies of freshwater and estuarine constructed wetlands for phenolic endocrine disruptor removal in Taiwan

We examined the distribution and removal efficiencies of phenolic endocrine disruptors (EDs), namely nonylphenol diethoxylates (NP2EO), nonylphenol monoethoxylates (NP1EO), nonylphenol (NP), and octylphenol (OP), in wastewater treated by estuarine and freshwater constructed wetland systems in Dapeng Bay National Scenic Area (DBNSA) and along the Dahan River in Taiwan. Water samples were taken bimonthly at 30 sites in three estuarine constructed wetlands (Datan, Pengcun and Linbian right bank (A and B)) in DBNSA, for eight sampling campaigns. The average removal efficiencies were in the range of 3.13–97.3% for wetlands in DBNSA. The highest average removal occurred in the east inlet to the outlet of the Tatan wetland. The most frequently detected compound was OP (57.7%), whose concentration was up to 1458.7ng/L in DBNSA. NP was seen in only 20.5% of the samples. The temporal variation of EDs showed a decrease across seasons, where summer>spring>winter>autumn in these constructed wetlands. The removal efficiencies of EDs by estuarine wetlands, in decreasing order, were Datan>Pengcun>Linbian right bank in DBNSA. Water samples collected at 18 sites in three freshwater constructed wetlands (Daniaopi, Hsin-Hai I, and Hsin-Hai II) along the riparian area of Dahan River. NP2EO was the most abundant compound, with a concentration of up to 11200ng/L. Removal efficiencies ranged from 55% to 91% for NP1EO, NP2EO, and NP in Hsin-Hai I. The average removal potential of EDs in freshwater constructed wetlands, in decreasing order, was Hsin-Hai II>Daniaopi>Hsin-Hai I constructed wetlands. The lowest concentrations of the selected compounds were observed in the winter. The highest removal efficiency of the selected phenolic endocrine disruptors was achieved by Hsin-Hai I wetland. The calculated risk quotients used to evaluate the ecological risk were up to 30 times higher in the freshwater wetlands along Dahan River than in the estuarine (DBNSA) constructed wetlands, indicating that existing concentrations of these EDs in wetland systems pose a high ecological risk to aquatic organisms. The decreasing risk quotient from influent to effluent indicates that phenolic endocrine disruptors can be treated in these constructed wetlands. Our results of this research can serve as a preliminary understanding on the ED removal efficiencies in different types of constructed wetlands.

Environmental and biogeochemical changes following a decade's reclamation in the Dapeng (Tapong) Bay, southwestern Taiwan

This study examines the environmental and biogeochemical changes in Dapeng (formerly spelled Tapong) Bay, a semi-enclosed coastal lagoon in southwestern Taiwan, after two major reclamation works performed between 1999 and 2010. The lagoon was largely occupied by oyster culture racks and fish farming cages before December, 2002. Substantial external inputs of nutrients and organic carbon and the fairly long water exchange time (τ) (10 ± 2 days) caused the lagoon to enter a eutrophic state, particularly at the inner lagoon, which directly received nutrient inputs. However, the entire lagoon showed autotrophic, and the estimated net ecosystem production (NEP) during the first stage was 5.8 mol C m−2 yr−1. After January, 2003, the aquaculture structures were completely removed, and the τ decreased to 6 ± 2 days. The annual mean concentrations of dissolved oxygen increased, and nutrients decreased substantially, likely due to improved water exchange, absence of feeding and increased biological utilization. The NEP increased 37% to 7.7 mol C m−2 yr−1 after structure removal. The second reclamation work beginning from July, 2006, focused on establishing artificial wetlands for wastewater treatment and on dredging bottom sediment. Although the τ did not change significantly (8 ± 3 days), substantial decreases in nutrient concentrations and dissolved organic matter continued. The NEP (14.3 mol C m−2 yr−1) increased 85% compared to that in the second stage. The data suggest that the reclamations substantially improved water quality, carbon and nutrient biogeochemical processes and budgets in this semi-enclosed ecosystem.

Interpretation and Apportionment Source of Polycyclic Aromatic Hydrocarbons from Neighboring Rivers in Dapeng Bay (Taiwan)

The contents of 16 polycyclic aromatic hydrocarbons (PAHs) and surface sediment properties were analyzed from 31 locations in Dapeng Bay and neighboring rivers (i.e., Kaoping River, Tungkang River, and Lingbeng River) in Taiwan. Principal component factor analysis (PCFA) showed that the most important latent factors are the soil-texture-caused factor, the PAHs-caused factor, and the nutrient-caused factor. Contour maps incorporating factor scores showed that phenanthrene and pyrene of PAHs had the highest content at the entrance of the northern side of the lagoon. Benzo(a)pyrene had the highest content located in the midsection of the Kaoping River and in Dapeng Bay. Moreover, canonical discriminant analysis shows that sediment quality in Dapeng Bay was not similar to the other three rivers. The methodologies and results provide useful information on watershed management and may be applicable to other basins with similar properties that are experiencing similar coastal environmental issues.

To Recognize Sources of Pollution in Dapeng Bay by Sediment Quality in Southern Taiwan

Canonical discriminant analysis (CDA) was applied in order to distinguish the sediment-quality parameters from neighboring rivers, and to recognize similarities of sediment properties between lagoon and neighboring rivers. Two set of constructed discriminant functions showed a marked contribution to most of the discriminant variables. In sediment, the significantly parameters - porosity, Cd, Cr, Al, and Pb were combined as the heavy metal factor. The recognition capacities of the two discriminant functions were 82.6 and 17.4, respectively. The Dapeng Bay had no significant similarity with the three neighbouring rivers with the sediment properties.

Distribution and Sources of PAH&lt;sub&gt;S&lt;/sub&gt; and Sediment Properties in Southern Taiwan

Abstract. The concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) and surface sediment properties were analyzed from 31 locations in Dapeng Bay and neighboring rivers (Kaoping River, Tungkang River and Lingbeng River), southern Taiwan. Principal component factor analysis (PCFA) was performed to explain the latent factors and spatial variations of sediment quality. And canonical discriminant analysis (CDA) was applied to identify the source of pollution of Dapeng Bay from neighboring rivers. The results show that the most important latent factors in Dapeng Bay and neighboring rivers on wet seasons are the soil texture caused factor, the PAHs caused factor, and the nutrient caused factor. Contour maps incorporating the factor scores showed phenanthrene (Phn) and pyrene (Pyr) of PAHs had the highest content at the entrance of the northern side of the lagoon. Benzo(a)pyrene (BaP) had the highest content located in mid-section of the Kaoping River and in Dapeng Bay. Total nitrogen (TN) and total phosphate (TP) had the highest content located in the last-section of Tungkang River. And CDA shows that sediment quality in Dapeng Bay was not similar to the other three rivers.

Heterotrophic bacteria of the Dapeng Bay in the South China Sea: community structure, abundance, and the relationships of culturablity with environmental factors

The community composition, abundance and culturablity of heterotrophic bacterioplankton in the Dapeng Bay of the South China Sea were investigated by morphological method, bacterial cultivation and biochemical methods over an annual cycle. Aeromonas and Pseudomonas were the predominant genera among the Gram-negative bacteria. The bacterioplankton abundance fluctuated from 2.07×108 to 2.44×109 cells/dm3, and culturable bacteria abundance ranged between 0.1×106 and 16.07×106 CFU/dm3. The Culturablity of heterotrophic bacteria ranged between 0.01% and 1.31%. The relationship between bacterial culturablity and the environmental factors was also studied in different sites of the Dapeng Bay. Throughout the bay, a significantly positive relationship was evidenced between bacterial culturability and temperature, meanswhile bacterial culturability was significantly inversely related with salinity. The positive relationship was shown at the central bay while a negative relationship was observed at the bay mouth and there was no significant correlation at top bay between bacterial culturablity and chlorophyll a of sea water. A positive relationship was found between culturability and DIN all the bay, but DIP showed a significantly negative relationship with bacterial culturability only at the mouth of the bay.

The influence of lagoon on neighboring rivers by water and sediment quality

Canonical discriminant analysis (CDA) was applied in order to distinguish the water-quality and the sediment-quality parameters from neighboring rivers, and to recognize similarities of water and sediment properties between a lagoon and neighboring rivers. Two set of constructed discriminant functions showed a marked contribution to most of the discriminant variables. In water, the significant parameters - the total nitrogen, algae, dissolved oxygen and total phosphate - were combined as the nutrient effect factor. The recognition capacities of the two discriminant functions were 95.6 and 4.4%, respectively; the Kaoping River showed the most similarities with the water quality in Dapeng Bay; in sediment, the significant parameters porosity, Cd, Cr, Al, and Pb were combined as the heavy metal effect factor. The recognition capacities were 82.6 and 17.4%, respectively, but the sediment properties in these three rivers had no significant similarity with the Dapeng Bay.