bluuebunny/crossref_metadata_2025 huggingface dataset:
Abundance and spatial distribution of Mysis diluviana in Lake Ontario in 2008 estimated with 120 kHz hydroacoustic surveys and net tows
Authors: Watkins James M. , Rudstam Lars G. , Connerton Michael J. , Schaner Ted , Rudstam Per G. , Bowen Kelly L.
Published: October 2017

Mysids are an important component of Great Lakes foodwebs, both as a prey for fish and as a predator on zooplankton. We monitored mysid abundance in Lake Ontario using lake-wide hydroacoustics data and vertical net hauls collected 1–5 August 2008 during the Ontario Ministry of Natural Resources and New York State Department of Conservation forage fish survey. Acoustic volume backscattering strength was highly correlated with both density and biomass of mysids although the correlation with biomass was stronger. The slopes of these relationships were not significantly different from theory (0.10) indicating a linear relationship between abundance and backscattering strength. Size structure significantly affected the relationship between backscattering strength and density but not between backscattering strength and biomass. Average target strength for areas with small mysids was −91.9 dB per mysid, and in areas with both small and large mysids it was −88.2 dB per animal. Acoustic estimates for Lake Ontario calculated with these regressions provided a lake-wide estimate weighted by lake area within depth intervals, of 228 mysids m−2 (CV 17.6%) and 0.93 g dw m−2 (CV 12.9%). Density and biomass in 14 net hauls averaged 316 mysids m−2 (range 0 to 1113) and 1.35 g dw m−2 (range 0 to 3.89). Mysid biomass was 33% of the biomass of other crustacean zooplankton in the summer of 2008. As in 2005, areas of low mysid abundance were detected in the middle of the transects and along the north shore. Lakewide mysid abundance in the summer of 2008 was higher than in a similar acoustic survey in the summer of 2005 and in whole-lake autumn 2000–2007 net surveys, suggesting that mysids are persisting in Lake Ontario and abundant relative to other Great Lakes.
Management of Great Lakes fisheries: Progressions and lessons
Authors: Minns Charles K.
Published: October 2017

Fishery resources include the fishes, the other biota they interact with, and the habitats they occupy. The historical sequences in the use and management of these resources may be considered as a series of interacting sequences of change. These sequences can span from social, economic, institutional and landscape changes, through water quality, habitat supply, and climate changes, to biotic composition changes, introductions and extinctions, and species harvest changes. A selection of these sequences is examined for the St. Lawrence-Great Lakes which has been subjected to intense development and study over the last 200 years. While the whole basin is considered, some detailed attention is given to Lake Ontario and, within it, the Bay of Quinte. Brief selective development histories are given for the three areas as context. The management history is outlined and critiqued. While much progress has been achieved in cleaning up the load-driven problems in the basin, little secure progress toward rehabilitation and sustainability has been achieved. In the current period of economic problems, governments, particularly Canada’s, are undoing past ecosystem management progress.

The development of St. Lawrence-Great Lakes’ ecosystem science has drawn heavily from both oceanography and limnology. A brief, selective overview of several progressions in ecosystem science illustrates how knowledge and understanding of this ecosystem has expanded over the last 60 years, providing an improved basis for management action. As with use and management, the science of fishery resource management has consisted of many historical progressions. The many sequences in the St. Lawrence-Great Lakes management and science histories lend support for recognition of (i) the importance of taking an ecosystem approach to renewable resource management, (ii) the value of adaptive management practices and, particularly, (iii) the vital complementary roles of long-term monitoring and mathematical modelling.
Can multi-frequency acoustics improve the monitoring of large zooplankton in large temperate lakes?
Authors: Ragnarsson-Stabo Henrik , Vrede Tobias , Axenrot Thomas , Sandström Alfred
Published: October 2017

Large zooplankton has an important role for the functioning of the ecosystem in many lakes. Most are predatory, which makes them both competitors as well as food for many planktivorous fish species. In general, it has been elusive to measure the abundance of this group of zooplankton with traditional sampling methods, particularly in large volumes of water. In this study we tested the potential and adequacy of multi-frequency hydroacoustics as a method to map the spatial patterns in abundance of the large zooplankton in Lake Vänern, Lake Vättern and Lake Mälaren. In addition, we used a plankton net to groundtruth biovolume estimates vertically, and a Tucker trawl for the horizontal distribution. Two frequencies were used to separate the acoustic backscattering from fish, mysids and plankton. The main target species were Leptodora kindtii, Bythotrephes longimanus and Limnocalanus macrurus.

The plankton communities were very heterogeneous both within and among the lakes. Lake Vänern and Lake Mälaren were dominated by Leptodora, whereas Lake Vättern was dominated by Limnocalanus. Bottom depth at the sample site was the most important community structuring factor.

Our results indicate that the biomass of large predatory zooplankton is comparably high and in most surveyed areas even higher than the biomass of planktivorous fish. Consequently, they are more important for the dynamics of lake food webs than previously assumed. Using multi-frequency hydroacoustics show promising results and with some alterations to the sampling design this would be a valuable addition to the traditional zooplankton monitoring in large lakes.
Lake Ontario water quality during the 2003 and 2008 intensive field years and comparison with long-term trends
Authors: Holeck K. T. , Rudstam L. G. , Watkins J. M. , Luckey F. J. , Lantry J. R. , Lantry B. F. , Trometer E. S. , Koops M. A. , Johnson T. B.
Published: October 2017

Phosphorus loading declined between the 1970s and the 1990s, leading to oligotrophication of the offshore waters of Lake Ontario during that time period. Using lake-wide data from the intensive field years of 2003 and 2008 and from available long-term data sets on several trophic state indicators (total phosphorus [TP], soluble reactive silica [SRSi], chlorophyll a and Secchi disc transparency [SDT]), we tested the hypothesis that oligotrophication of the offshore waters of Lake Ontario has continued in the 2000s. Significant differences between 2003 and 2008 include higher spring (April) TP, SRSi, and SDT in 2008, lower summer (July–August) SDT in 2008, higher summer chlorophyll a in 2008, and lower fall (September) TP, SRSi, and chlorophyll a in 2008. The decline in SRSi from spring to summer was greater in 2008 than in 2003. Change point and regression analyses on the long-term data revealed no trend in spring TP since 1996, in summer chlorophyll a since 1994, in spring SDT since 1998, in spring SRSi or SRSi decline from spring to summer since 1999, or in summer SDT since 2001. Neither the comparison of the 2003 and 2008 surveys nor the analysis of the long-term data supported our hypothesis of continued oligotrophication of the offshore of Lake Ontario in the 2000s.
Ecosystem health of Lake Vänern: Past, present and future research
Authors: Dave G. , Munawar M. , Wängberg S.-Å.
Published: October 2017

The large lakes of Sweden (Vänern, Vättern, Mälaren and Hjälmaren) have been monitored for more than four decades for water quality conditions to assess the impact of eutrophication from anthropogenic activities. Lake Vänern is basically an oligotrophic lake that showed signs of eutrophication, notably the emergence of algal blooms in the coastal areas (1967–1968). The lake was also contaminated, due to the discharge of pulp and paper effluents including metals such as mercury. However, ecosystem-based information is lacking for Lake Vänern. Consequently a symposium was organized in 2012 by the University of Gothenburg, Mötesplats Vänersborg and the Aquatic Ecosystem Health and Management Society to: assess the current status of the health of Lake Vänern's ecosystem, identify knowledge gaps and develop a road map for the future. In this regard, Lake Vänern was compared with the North American Great Lakes to learn from their extensive, long-term data sets. A special issue devoted to the “State of Lake Vänern Ecosystem” symposium was published in Aquatic Ecosystem Health and Management (AEHM, Vol. 17, no. 4) including keynotes and contributed papers. The conclusions shown in the appendix (available in the online supplementary information) summarize the authors' contributions. Most of the articles covered Lake Vänern, but some were directed towards monitoring and management of Great Lakes in general, and others addressed co-operation under the auspices of international agreements and directives. Based on the background information provided by the State of Lake Vänern Ecosystem symposium and its publication in the special issue, the conveners decided that a synthesis of the symposium with recommendations for the future would be useful in boosting ecosystem research in Lake Vänern.
More than propagule pressure: Successful invading algae have physiological adaptations suitable to anthropogenically changing nutrient environments
Authors: Glibert Patricia M.
Published: October 2017

While increased propagule pressure may increase the possibility of success of an invading species, success is also a function of the environment to which the organisms have been introduced and the physiological strategies of the invading organisms and how those strategies relate to those of the native fauna or flora. Using examples of altered nutrients in aquatic environments, the effects of environment on the success of harmful algae are herein considered. Many harmful algae are introduced species, especially via ballast water. While increasing numbers and frequency of harmful algal blooms in eutrophic waters may be comparatively easy to understand—more nutrients, more biomass, more opportunities for species to proliferate—one of the more perplexing issues is why some harmful algal bloom species seem to become more prevalent under conditions of disproportionate nutrient supply. Focusing here specifically on the case of excess nitrogen loading relative to that of phosphorus, there are a number of key adaptive strategies that may allow certain types of harmful algal blooms to thrive. Successful invaders may be smaller in cell size, thereby reducing phosphorus cellular demands, and they may have nutrient substitution or acquisition strategies allowing them to use a source of nutrient not otherwise available to competitors. They may also create local environmental changes, such as increases in pH that detrimentally affect competitors while altering sediment biogeochemical processes increasing efflux of the otherwise limiting nutrient. Finally, their growth and cellular elemental stoichiometry also affect food quality for grazers, including toxin production, which has been shown in numerous species to increase when the cells are not grown under nutrient-balanced conditions. Through their detrimental effects on grazers, they may further destabilize ecosystem environments increasing susceptibility for additional ecosystem changes, including creating environmental conditions suitable for additional invasions to occur.
A winter chlorophyll bloom analyzed using Lagrangian diagnoses in the northeastern South China Sea
Authors: Li Weijie , Tang Shilin , Zhan Haigang
Published: October 2017

The Finite Time Lyapunov Exponent technique is a highly effective way to visualize and analyze flow fields. Its ridges are referred to as Lagrangian Coherent Structures which reveal the transport barriers of fluid systems, or their hidden skeletons. This allows us to investigate the complex mesoscale and submesoscale ocean processes on a Lagrangian view. In this article, we use the Lagrangian technique to investigate one chlorophyll bloom event in the northeastern South China Sea and discuss the impact of horizontal transport on the distribution of surface chlorophyll. Our results demonstrate that horizontal transport barriers uncovered by Lagrangian Coherent Structures can shape the vortex and filament in a simple and distinct way.
An observed cyclonic eddy associated with boundary current in the northwestern South China Sea
Authors: Li Junmin , Jing Zhiyou , Jiang Senhui , Wang Dongxiao , Yan Tong
Published: October 2017

A cyclonic eddy detected in the northwestern South China Sea during the summer of 2011 is investigated using both satellite data and several sets of in situ observations including cruise measurements and a mooring line. The eddy was generated to the west of the Zhongsha Islands in early June and then propagated northwestward. In July and August, when the cyclonic gyre originating from the offshore jet recirculation east of Vietnam matured, the eddy was absorbed into the gyre and strengthened by it. The eddy regulated the thermohaline characteristics and the currents of the entire water column. Along-slope boundary currents (toward the northeast in summer) were completely reversed from the surface to about 1300 m below. The thermohaline in deep water (660–950 m) showed a significant response to the presence of the eddy, with the isotherms and isohalines rising up to 100 m. The recurrence of the phenomenon is further explored by a statistical analysis of satellite observations. Results suggest the presence of a cyclonic eddy and abnormal offshore jets are closely associated with the El Nino Southern Oscillation events.
Observation and numerical simulation of the marine meteorology elements and air-sea fluxes at Yongxing Island in September 2013
Authors: Shi Rui , Zeng Lili , Chen Ju , Yang Lei , Dong Lingyu , He Yunkai , Li Daning , Yao Jinglong
Published: October 2017

The variation of marine meteorology elements and the heat flux at Yongxing Island were investigated in September 2013 using observational data collected by the Yongxing Island Air–Sea Flux Tower. Heat flux was measured through eddy covariance and estimated using the bulk flux method. The traditional thirty-minute average method was employed to analyze the eddy covariance data. A TOGA–CORE 3.0 Algorithm was used to estimate the bulk flux. Capacity of the Advanced Weather Research and Forecasting model to simulate the variations in marine meteorological elements was evaluated using the observational data obtained during the same period. Observations suggested a response by the different parameters that were synchronous to the retreat of the monsoon around 7 September 2013. Surface air masses became cool and dry, and the downward short (long) wave radiation was reduced (increased). The Weather Research and Forecasting model simulated the variation of the atmospheric elements well, as observed by the Air-Sea Flux Tower in September 2013. The model was very accurate in simulating surface wind, radiation, and scalar–humidity. However, it failed to simulate the dramatic variations of surface air temperature, though it successfully reproduced the retreat of the summer monsoon, but weakened during the onset of the typhoon. The sensible flux simulated through the model was between the fluxes estimated through the bulk flux and eddy covariance flux. It also overestimated the latent heat flux at times, particularly after 20 September.
A case study of the near-inertial oscillations near the Xisha Islands in the South China Sea during the passage of typhoon Conson 2010
Authors: Liu Junliang , Cai Shuqun , Wang Dongxiao , He Yunkai
Published: October 2017

Near-inertial oscillations in the northern South China Sea, close to the Xisha Islands, during the passage of typhoon Conson, were investigated using 52-day observational data and a damped slab model. Using spectral analyses, we found that these near-inertial oscillations were dominated by clockwise components. The observed, as well as simulated, inertial currents matched well before and after the passage of the typhoon, which revealed that significantly enhanced oscillations were induced by the typhoon. They have a peak frequency of 0.0237 cycles per hour, which is 2% lower than the local inertial frequency, meaning a red-shift phenomenon exists, even in shallow water. The red-shift might be attributed to the background negative vorticity. Additionally, we found that the barotropic near-inertial currents were more significant after the passage of the typhoon. The position of the maximum intensity of near-inertial current shear with a period of 20.8 h was found to propagate upward slowly with time before the passage of the typhoon.
Sediment phosphorus forms and levels in two tropical floodplain wetlands
Authors: Samanta Srikanta , Debnath Debashri , Maitra Nilanjan , Banerjee Moumita , Chowdhury Atalanta Narayan , Sharma Anil Prakash , Manna Sanjib Kumar
Published: October 2017

Inorganic phosphorus is one of the critical nutrients determining trophic state and freshwater productivity. Sediment may act as a sink or source of phosphorus to the overlying water depending on its pH, redox state, various forms of phosphorus present, etc. To examine potential sorption or mobilization of sediment phosphorus in floodplain wetlands, the amount and distribution of phosphorus fractions were evaluated using a sequential chemical extraction procedure. Exceedingly high levels of total phosphorus (mean: 6040 ± 344, 5470 ± 363 mg kg−1), consisting largely of organic and refractory fraction (70 – 98%), followed by calcium-phosphorus (mean: 584 ± 31.3, 143 ± 8.42 mg kg−1) and iron-phosphorus (mean: 108 ± 10.1, 91.0 ± 7.68 mg kg−1) were recorded respectively in Bhomra and Akaipur wetlands of West Bengal, India. The inorganic phosphorus, comprising the loosely sorbed phosphorus and all the mineral bound forms contributed only about 6–14% to the total phosphorus indicating their less significance in phosphorus sorption or desorption in these tropical wetlands. Although the loosely sorbed phosphorus was in moderate level (2.69 ± 0.69, 1.54 ± 0.53 mg kg−1), water dissolved phosphorus was recorded at higher concentrations (mean: 0.16 ± 0.02 mg l−1 in Akaipur and 1.08 ± 0.12 mg l−1 in Bhomra). However, the higher level of water available phosphorus was not reflected in plankton production since the dominance of weeds suppresses their growth. This study recorded large accumulation of organic matter and nutrients in the form of detritus in these wetlands which may be channelized for fish production through stocking of suitable detritivorous fishes and/or reducing macrophyte coverage that would give space and nutrients for phytoplankton growth.
High-frequency variability of latent-heat flux in the South China Sea
Authors: Shi Rui , Zeng Lili , Wang Xin , Sui Dandan
Published: October 2017

Synoptic-scale disturbances of latent-heat flux in the South China Sea are examined using Xisha automatic weather station measurements and satellite-derived daily latent heat-flux datasets. The power spectra of observations suggest a synoptic feature with a pronounced energy peak at a period of 4–8 days, comparable with the timescales of the atmospheric synoptic variabilities in the region. The characteristics of the synoptic latent-heat flux variations in summer are remarkably different from those in winter. The amplitudes of significant synoptic oscillations are about 20 and 40 W·m−2 during summer and winter monsoons, respectively. An active monsoon is clearly correlated with positive and negative phases of the synoptic latent-heat flux oscillations in the South China Sea. Using a composite analysis, some fundamental features of the synoptic latent-heat flux variabilities were revealed. In summer, the synoptic-scale latent-heat flux fluctuations are highly correlated with wind speed. While the synoptic variations of winds were removed during summer, the latent-heat anomalies precede about 1 day. In winter, however, they are primarily associated with winds and near-surface air humidity. When the synoptic oscillations of near-surface air humidity are removed, the amplitude of the composite latent-heat flux is reduced by 70%.
Aquatic vegetation trends from 1992 to 2012 in Hamilton Harbour and Cootes Paradise, Lake Ontario
Authors: Leisti K. E. , Theÿsmeÿer T. , Doka S. E. , Court A.
Published: October 2017

Over the past two hundred years, anthropogenic activities have resulted in the substantial decline of the once extensive wetlands in both Hamilton Harbour and Cootes Paradise. Some of the key stressors for aquatic vegetation have been infilling, sustained high water levels and level regulation in Lake Ontario, and reduced water clarity because of eutrophication and suspended sediments. Designated an Area of Concern in 1985, remediation efforts have included upgrades to the sewage treatment plants discharging into the harbour to reduce eutrophication and the 1996 construction of a fish barrier to exclude large Carp from entering Cootes Paradise to reduce turbidity. Over the past ten years, Cootes Paradise has seen a 120% increase in the areal extent of emergent vegetation, but this still represents less than 20% of the circa 1900's marsh area. Despite substantial reductions in Carp density in Cootes Paradise, submerged aquatic vegetation has been sparse and typically found at depths of less than 0.5 m, likely because of impaired light penetration.

Following a significant improvement in water clarity in Hamilton Harbour between 1987 and 1997, submerged aquatic vegetation in the harbour proper expanded, achieving a mean maximum depth of 2.9 m in 2012. Species richness was considerably lower in Hamilton Harbour when compared to Cootes Paradise; however, the species composition in both these areas indicated degraded conditions throughout the time period of our assessment. Using our recent dataset, we tested relationships that had been previously established in the literature between emergent extent and water levels for Cootes Paradise and also the connection between maximum depth of submergent colonization and Secchi depths but simple univariate tests were not significant. A combination of small sample size, simple tests, and a small range for the independent variable may be issues in establishing simplified response relationships and are likely oversimplifications of vegetation response in the area that require more complex modelling.
Ambiguous influences of omnivorous fish on trophic cascade and alternative states: Implications for biomanipulation from an ecological model
Authors: Li Junmin , Huang Ping , Zhao Zhuangming , Zhang Renduo
Published: October 2017

An ecological model was developed to systematically analyze the comprehensive influence of omnivory level and predation intensity of fish on the dynamic state and strength of trophic cascade of a lake ecosystem. Results showed that a higher fish omnivory level reduced the strength of trophic cascade and increased the occurrence of alternative states, while an increase in predation intensity resulted in opposite effects. With the combination of these two factors, the occurrence of alternative states was dependent on the relative increase in the predation intensity. The model was further applied to a subtropical shallow lake in China. Modeling results revealed that the heavy stock of omnivorous fish in the lake increased the occurrence of alternative states and decreased the strength of trophic cascade. Results indicated that the long-term effect of biomanipulation would be significant and therefore high rates of fish removal would be required. The information from this study indicated the importance of understanding the dynamic state and strength of trophic cascade when predicting the long-term effects of biomanipulation.
Integration of best management practices in the Bay of Quinte watershed with the phosphorus dynamics in the receiving waterbody: What do the models predict?
Authors: Arhonditsis George B. , Kim Dong-Kyun , Shimoda Yuko , Zhang Weitao , Watson Sue , Mugalingam Shan , Dittrich Maria , Geater Kristin , McClure Christine , Keene Bryon , Morley Andrew , Richards Agnes , Long Tanya , Rao Yerubandi R. , Kalinauskas Rimi
Published: October 2017

We present a modelling analysis of the management practices that could lead to significant reduction of phosphorus export from the Bay of Quinte watershed and an evaluation of the overall uncertainty associated with the assessment of the Beneficial Use Impairment Eutrophication and Undesirable Algae. Our work highlights the internal recycling as one of the key drivers of phosphorus dynamics in the Bay. The flow from the Trent River is the predominant driver of the upper Bay dynamics until the main stem of the middle area however, the sediments in the same segment release a significant amount of phosphorus and the corresponding fluxes are likely amplified by the macrophyte and dreissenid activity. From a management standpoint, the presence of a significant positive feedback loop in the upper Bay suggests that the anticipated benefits of additional reductions of the exogenous point and non-point loading may not be realized within a reasonable time frame (i.e. 5—10 years). Our analysis of nutrient loading scenarios shows that the restoration pace of the Bay could be slow, even if the riverine total phosphorus concentrations reach levels significantly lower than their contemporary values, <25 µg TP l−1. We believe that the on-going management decisions, monitoring, and modelling should also explicitly consider the role and broader ramifications of internal phosphorus loading into the system. The anticipated lessons from such a multi-faceted exercise are a unique aspect of the Bay of Quinte ecosystem because of the long history of research and monitoring data. This study can produce transferable knowledge to other systems worldwide, experiencing similar hysteresis patterns associated with internal nutrient loading.
Mud Crab (Scylla serrata) population changes in Koggala Lagoon, Sri Lanka since construction of the groyne system
Authors: Amarasekara G. P. , Priyadarshana T. , Manatunge J. , Tanaka N. , Gunaratne G. L.
Published: October 2017

This study was conducted to determine the present status of the Mud Crab (Scylla serrata Forskal) population in Koggala Lagoon, including details on size at maturity, sex ratio and carapace width - body weight relationship. This Crab is the most common edible Crab species found in the lagoon, comprising 93.10% of total catch from crab pots and 89.86% of total catch from crab nets. Sex ratios (male:female) were 1:0.86 and 1:0.82 in crab pots and nets, respectively. Female crabs of various sizes were randomly sampled to determine size at maturity. The results indicate that size at maturity of females was 12.17 cm carapace width. Size at maturity of males could not be determined using external characteristics. Population parameters were estimated from length-frequency data collected in 2009 and 2011. Asymptotic carapace length (L∞) and growth constant (K) were estimated to be 20.12 cm, 0.91 yr−1 in 2009 and 19.27 cm, 3.2 yr−1 in 2011, respectively. Exploitation rates were 0.32 in 2009 and 0.44 in 2011. There was a significant difference in Crab size between harvests by the crab nets versus traditional crab pots. Results indicate that S. serrata population is declining due to over-fishing as of increased fishing gear efficiency from traditional crab pots to modern crab nets. Commercial catches of crab net and crab pots comprised 85.7% and 72.0% of immature females, respectively, based on the size at first maturity revealed by this study. In order to maintain natural health of the Mud Crab population, immediate management action is needed to regulate fishing in Koggala Lagoon.
Dianchi Lake, China: Geological formation, causes of eutrophication and recent restoration efforts
Authors: Liu Xujun , Wang Hailing
Published: October 2017

Dianchi Lake belongs to the Jinshajiang River system of the Yangtze River Basin. Due to the fast growth of economic and social development, Dianchi Lake has lost its self-purification capability and suffers from serious eutrophication. This study summarized historic trajectory of the ecological and environmental changes in the lake basin, with emphasis on the changes of physical, chemical, biological, and ecological characteristics of the lake as well as the social development in recent years. Despite the great efforts initiated by the government aiming at restoration of the environmental quality of the lake, the results were not substantially significant. We believe that a comprehensive lake model is imperative to understand the ecological functions of the lake and establish scientifically defined realistic goals for the restoration. In addition, continual modernization of rural area and certain adjustment in population decentralization in the lake basin area will help reduce the environmental pressure.
Seasonal variations of sea level anomaly in the subtropical front zone based on satellite-derived data from 2003–2009
Authors: Qiu Chunhua , Chen Jie , Shangguan Maosen , Mao Huabin
Published: October 2017

We investigated seasonal variations in the sea level anomaly in the northwestern Pacific subtropical front zone using weekly satellite-derived products and in situ observations from 2003 to 2009. The sea level anomalies had different seasonal cycles in the cold, front and warm zones. In the former two zones, peak values appeared (∼15 cm) in July–August and hollow values (∼−10 cm) in February–March; in the warm zone, sea level anomalies had no apparent seasonal variations. We found that the correlation between sea level anomaly and sea surface temperature reached values of 0.76 in the cold and front zones, but only 0.38 in the warm zone. The steric height anomaly explained 70% variances of sea level anomaly in the former two zones but only 25% in the warm zone. We examined the mechanisms of the different patterns of sea level anomaly variation among the three different zones and concluded that the steric height anomaly induced by air–sea heat exchanges controlled the seasonal variations of sea level anomaly in the former two zones, while the barotropic term accompanied with subtropical countercurrent lead to the obscure seasonal variations in the warm zone. These high frequency variations merit future study.
The character of chlorophyll-a and its grey relationship with nitrate in the Pearl River estuary in summer
Authors: Wang Yinxia , Zeng Jisheng , Chen Lei , Lou Quansheng , Xie Jian , Huang Huamei , Gao Yang
Published: October 2017

Based on the data of chlorophyll-a, nitrate and nitrite derived from the samples collected from the Pearl River estuary during 2004 to 2008, the spatial-temporal character of chlorophyll is analyzed and the correlation between chlorophyll-a, nitrate, and nitrite is studied using Grey System Theory. The distribution of chlorophyll has significant annual variation. There are two high chlorophyll regions, lying around the Wanshan Islands and the Qi'ao Islands, and the high chlorophyll distribution always exists near the Wanshan Islands during all the observed years. There is a good grey correlation between chlorophyll and nitrite, especially around the Qi'ao Islands. From the Lingding Sea to the Shenzhen coast, the grey correlation is not as significant as that in other regions. Except for the Humen and Shenzhen bay stations, all the other stations have a positive degree of grey relation. The sign of the grey relation degree between chlorophyll and nitrate has an obvious spatial difference, with a negative correlation near the coast and a positive correlation in the estuarine region.
Status of macrobenthic diversity and distribution in Subei Shoal, China
Authors: Xu Yong , Li Xinzheng , Wang Hongfa , Zhang Baolin
Published: October 2017

Five cruise surveys were carried out in May–June 2013 to evaluate the status of macrobenthic diversity and distribution in Subei Shoal, China. Twenty-four stations were sampled and divided into four groups according to depth (5–10 m, 10–20 m, 20–30 m and 30–35 m). A total of 163 species were collected with Polychaeta dominating in species composition and abundance. All of the community parameters (abundance, biomass, mean species richness, Margalef richness index, Shannon-Wiener index and Pielou's evenness) were not significantly different among the five cruises or among the four groups, except that Shannon-Wiener index at 5–10 m was significantly lower than that in other depth groups. No significant difference in community structure was detected among cruises, but when the data from the same station were pooled together, significant differences among stations were observed basically from inshore to offshore. The benthic opportunistic polychaetes amphipods index showed four stations having moderate ecological status in Subei Shoal. Canonical correspondence analysis showed that Sigambra bassi and Praxillella sp. were positively correlated with depth and salinity, and Paralacydonia paradoxa was positively correlated with dissolved oxygen.
Statistical analysis of macroinvertebrate assemblage structure in relation to river-health assessment of an urban river, Eastern Cape, South Africa
Authors: Odume Oghenekaro Nelson , Mgaba Ntombekhaya
Published: October 2017

Urban rivers in developing countries, including South Africa, are increasingly being impacted by human activities. The Bloukrans and Palmiet Rivers, where the current study was undertaken, are no exception. The Bloukrans River, the main object of this study, was impacted by wastewater effluent discharges and run-off from informal settlements and agricultural activities. The present study was aimed at evaluating the ecological health of the Bloukrans River using macroinvetebrate-based biomonitoring approaches, including the biotic index (i.e. the South African Scoring System version 5), multimetric and multivariate analyses of the assemblage structure. 18 metrics were selected and their potential for discriminating between the control and impaired sites evaluated. Macroinvertebrates were sampled bi-monthly (April – August 2013) at one control site (i.e. Site 1) in the Palmiet River and four impaired sites (i.e. Sites 2, 3, 4 and 5) in the Bloukrans River. The Scoring index indicated that the river health condition at the control site was good, whereas apart from Site 5, conditions at Sites 2, 3 and 4 were either poor or critically modified. Twelve metrics discriminated between Site 1 and the four impaired sites. Canonical correspondence analysis indicated that dissolved oxygen, electrical conductivity, nutrients and turbidity exerted the greatest influenced on the assemblage structure. Overall, the study indicated that pollution in the Bloukrans River had significant impact on the river health, influencing metrics in the diversity, composition and richness categories. The 12 metrics that proved sensitive to deteriorating water quality, enabling the discrimination of the control site from the impacted sites, could be used with the Scoring index to assess river health in the Bloukrans River. However, although using metrics in addition to the Scoring index provided greater understanding, where analytical resources are limited the summary biotic Scoring index can provide an acceptable rapid indication of river health.
Fishery resources of Sabah Al-Ahmad Sea City waterways: A potential contributor for Kuwait's fisheries
Authors: Nithyanandan Manickam , Jones David A. , Esseen Martin
Published: October 2017

Recent reports demonstrate that Arabian Gulf Shellfish and Finfish fisheries are in serious decline, in particular those of Kuwait. This decline is attributed to over fishing, pollution, loss of nursery ground, reduction in riverine input via the Shatt Al-Arab, and climate change. When completed in 2018, Sabah Al-Ahmad Sea City, Kuwait, will contain circa 200 km of waterways providing over 50% of extra coast line for Kuwait. Seine netting and gargoor traps have been deployed annually, since the first phase (A1) of this coastal township was opened to the sea in 2004, to monitor Shell and Fin fish populations within the waterways. Present work describes the diversity and abundance of commercial (edible and potential ornamental value) species now inhabiting the waterways, which comprise over 60% of the species marketed in Kuwait. Analysis of catch data reveals that the waterways act as spawning, nursery and feeding habitats for important species such as Epinephelus coioides (Orange-Spotted Grouper), Penaeus semisulcatus (Banana Shrimp) and Portunus segnis (Blue Swimming Crab). As no commercial fishing is allowed, the Sea City waterways act as a significant conservation area for Kuwait's fish stocks.
Abundance and composition of marine litter around Gökçeada Island (Northern Aegean Sea)
Authors: Gönülal Onur , Öz İdil , Güreşen Sedat Ozan , Öztürk Bayram
Published: October 2017

Marine debris are frequently studied on beaches and occasionally in coastal waters, but links between these two environments have rarely been studied. Litter items were collected by hand in the Gökçeada beaches supralittoral zone, consisting of sandy or rocky beaches, and collected from subtidal areas between 50–450 m depth range on the continental shelf with bottom trawling. Collected litter were sorted and categorized by type, usage and origin. On the beaches, litter density varied from 0.1 to 22.1 items per 100 m2. Plastic materials dominated the composition of waste materials (59%) followed by soft plastic, nylon (11.5%). Eight percent of litter was of foreign in origin coming from two countries (Greece and Bulgaria). Offshore, during 32 hauls only 12 items were collected, and the number of debris ranged from 0 to 1.6 items km−2. Gökçeada Island should be further monitored in order to develop regional marine litter management solutions.
Spatial variation in the health of coral reef communities of Palk Bay, southeast coast of India
Authors: Marimuthu N. , Ramachandran Purvaja , Robin R. S. , Tudu Debasis , Hariharan G. , Ramesh R.
Published: October 2017

This study was conducted to assess the health of the coastal ecosystem based on bio-physical assessment of the coral reef ecosystem at Palk Bay. A total of 11 sites along the coast from the eastern part of Rameswaram Island to Mandapam were chosen for this study. Good live coral cover (acroporid and non-acroporid corals) of 30.08 ± 6.72% was recorded in the eastern part of Rameswaram Island. Principal component analysis demonstrated that the contribution of live coral cover was closer to the selected study sites of the eastern part of Rameswaram Island. Metric multi-dimensional scaling analysis showed three major clusters with 75% similarity based on life-form categories observed in the reef ecosystem. In this study, there was a significant segregation of study sites of the eastern part of Rameswaram Island in two clusters with 80% similarity because of their richness of live coral cover. Multi-dimensional scaling based on coral species diversity showed three major clusters with 50% similarity. Principal component analysis showed that the major contribution and abundance of coral species were closer to the northern part of Rameswaram Island. Moreover, Shannon–Wiener species diversity index of this region was in the range of 1.592–1.856, which was higher than the other sites. Hence, it was observed that there is no relationship between mean live coral cover and coral species diversity index of the reef ecosystem. The impact of biological indicators such as Halimeda algae and Palythoa sp. (Zoanthids) on the reef ecosystem was also analyzed. About 31 species of live corals belonging to 9 families and 18 genera were recorded during the study period. The outcome of this study helped in the understanding of the health of the ecosystem based on the intensity of mean live coral cover and coral species diversity. It also made it easier to understand the longitudinal variations and distribution pattern of coral reef community categories.
Patterns of fish diversity, community structure and ecological integrity of River Yamuna, India
Authors: Sharma A. P. , Das M. K. , Vass K. K. , Tyagi R. K.
Published: October 2017

The Yamuna River, one of the most important and sacred rivers of the northern plains of India, is highly polluted. The river originates at the Yamunotri glacier, traverses 120 km to emerge onto the Indo-Gangetic plains at Dakpathar in Uttarakhand, and finally joins the Ganges River at Allahabad after traversing 1376 km. During 2007–2010 this study assessed the fish diversity, community structure, and ecological status in a 1200 km stretch of the river from Dakpathar to Allahabad. The waters were alkaline (pH 7.6–8.0). Dissolved oxygen was high at most sites (7.3–9.8 mg l−1), except at Wazirabad and Agra (3.4–3.7 mg l−1). A total of 143 fish species were recorded in the river. Cyprinidae was the most abundant family followed by Schilbeidae, Bagridae, and Sisoridae, respectively. The abundance was dominated by 48 species with = > 250 individuals caught. The highest intersite species similarities were recorded between Yamunanagar and Panipat, followed by Wazirabad and Hamirpur, and Yamunanagar and Allahabad. The middle stretch of the river was dominated by small-bodied erytopic, indigenous, and exotic fish species with periodic and opportunistic life history strategies, and had reduced abundances of the large–bodied, prized Indian Major Carps. A trophic shift towards dominance of carnivore catfish species was evident. Multivariate analysis indicated 83.50% of the total variability in species composition in the river could be attributed to gradients of the environmental variables: dissolved oxygen, turbidity, conductivity, total dissolved solids, stream velocity, and water temperature.

Insufficient flows in the middle stretch of the river have altered fish habitat availability, resulting in changes in fish composition and assemblage patterns. The study will aid efforts to conserve the aquatic communities and their habitats in the river.
Employing indicators for prioritization of fish assemblage with a view to manage freshwater fish diversity and ecosystem health in the tributaries of Ganges basin, India
Authors: Sarkar U. K. , Dubey V. K. , Singh S. P. , Singh Atul K.
Published: October 2017

The major tributaries of the river Ganges basin are currently threatened by various anthropogenic activities which are hampering the ecosystem stability and fish biodiversity of the basin. Multiple indicators were used to prioritize the fish assemblages in the tributaries and to develop an index that is responsive to human-induced environmental changes. A high percentage of invasive species was described with the orgin index at the most disturbed sites of rivers Gomti and Betwa which also represented a substantial amount of biological disturbance. The Fisheries Assessment Integrity Index based on ecological integrity of different segments of the rivers was used to prioritize different sampling sites of the tributaries. Some of the sampling sites in Gomti and Betwa rivers are reflecting disturbed fish assemblages, a very low Fisheries Assessment Integrity Index score, few threatened species, and a high proportion of invasive species. Principal components analysis of the sampling sites, along with fish assemblage, reflected the influence of the habitat parameters on structuring the assemblage pattern. This study identified depth, flow, water quality and land uses in shaping fish assemblages. The combination of various indices in this study should provide more accurate measures in identifying sites of high conservation value.
Fisheries of Indian Shad (Tenualosa ilisha) in the Hooghly–Bhagirathi stretch of the Ganga River system
Authors: Bhaumik Utpal
Published: October 2017

Tenualosa ilisha, the Indian Shad, is one of the most important commercial fish of the Indo-Pacific region and the Hilsa fishery in India is dependent on this species. Presently, the fishery resource of the species lies largely within the Bhagirathi–Hooghly component of the Ganga River system. The annual fish catch of Hilsa from the Bhagirathi–Hooghly River has fluctuated over the years ranging between 12,733 and 20,000 t between 2000–2001 and 2010–2012.

The monsoon migration of Hilsa commences in July and gradually picks up in August. From September onwards, the magnitude of migration to the freshwater system showed a declining trend. Stretches between Nischintapur and Diamond Harbour downstream, Hooghly Ghat and Kalna in the freshwater tidal zone, and Lalbagh to Farakka in the Bhagirathi River have been delineated as potential breeding grounds for Hilsa. The intense fishing pressure in the coastal estuarine zone almost year round, especially in breeding season, adversely affects the breeding migration, spawning, and recruitment success vis a vis overall fishery of Hilsa in the system. There is an immediate need to implement effective conservation measures to protect breeders, potential breeding grounds, and juveniles for the cause of sustainable Hilsa fishery.
A case study of the Narmada River system in India with particular reference to the impact of dams on its ecology and fisheries
Authors: Bhaumik Utpal , Mukhopadhyay M. K. , Shrivastava N. P. , Sharma A. P. , Singh S. N.
Published: October 2017

Narmada, the oldest river system in India, originates from Amarkantak in Madhya Pradesh, flows east-west, and joins with the Gulf of Cambay on the Arabian Sea. The river drains 45.64 km3 of annual run-off and a series of dams was proposed to hold some of its water resources for multipurpose use. Currently, three dams have been built in Madhya Pradesh and one is under construction in Gujarat. A comparison of pre- and post-impoundment eco-environment and fisheries revealed changes in water quality, productivity, and aquatic flora and fauna of the river system. Among the fish, species like Tor tor, Labeo fimbriatus and Labeo dyocheilus suffered most. The percentage contributions to total yield of Carp, Catfish, and miscellaneous groups have significantly changed, indicating falls of 17%, 36% and an increase of 410%, respectively. Percentage contributions to catches of Macrobrachium rosenbergii and Tenualosa ilisha have also declined by 46% and about 75% in the estuarine stretch of the river system. Suitable conservation measures for sustenance and development of fishery have been suggested.
Diversity and conservation status of freshwater fishes of the major rivers of northeast India
Authors: Vishwanath W.
Published: October 2017

Northeast India has rich freshwater fish diversity which is attributed to past geological history and the Himalayan orogeny which played an important role in the speciation and evolution of groups inhabiting mountain streams. The region is criss-crossed by numerous rivers belonging to the three major drainage systems: the Barak–Brahmaputra, the Kaladan and the Chindwin. About 100 species of fish have been described from the region by workers from India, as well as from other countries. Fish survey tours have been organized in the past 30 years in the different river systems of the region. Our survey resulted in the description of more than 50 new species of fish. As many as 40 species of fish are endemic to the Chindwin drainage and 22 to the Brahmaputra basin. The fish fauna of the Kaladan is poorly explored. Of the fish species in the Brahmaputra basin, 34% have not been evaluated for IUCN red list criteria, while in the Kaladan, 48.2% have not been evaluated.