Activity In Coastal Waters Research Articles

Identifying the key factors influencing spatial and temporal variations of regional coastal fishing activities

Fishing is one of the most pervasive human activities for harvesting natural resources. Accurate understanding of the dynamic variations of regional fishing activities and their influence mechanisms is crucial for marine conservation and fisheries management. Previous studies have described the spatio-temporal distribution of fishing operations. However, there is still a need for a comprehensive interpretation of why and how these variations occur, especially in regional coastal waters. In this study, taking the Bohai Sea and its adjacent waters as an example, the correlation between regional fishing activities and multiple factors, including the marine environment, geographical position, socio-economic conditions, and marine management policies, was investigated from the perspective of human geography. Automatic Identification System (AIS) data for fishing vessels were used, combining remote sensing, geographic information system (GIS), and statistical models. The results indicated that the spatio-temporal variations of regional coastal fishing activities were driven by complex interactions among these factors. Overall, the average explanatory power of socio-economic and geographical position factors on fishing activities was higher than that of marine environmental factors. The importance of the marine environment and geographical position for fishing activities varied throughout different seasons. The sensitivity of fishing activities to geographical position was relatively high, with the explained deviance exceeding 62% of the total explained deviance. Intensive fishing was primarily observed within a particular range of the sea surface temperature frontal gradient (0.20–0.60 °C/km) or sea surface chlorophyll-a frontal gradient (1.06–1.25). The spatial distribution of fishing activities is effectively constrained by implemented marine management policies. This study sheds new light on the key factors influencing regional fishing activities in coastal waters and highlights the complexity of their interaction effects. These findings can provide a theoretical basis for the restoration of fishery resources and marine fishing management.

Structurally stable but functionally disrupted marine microbial communities under a future climate change scenario: Potential importance for nitrous oxide emissions

The blue mussel Mytilus edulis is a widespread and abundant bivalve species along the North Sea with high economic and ecological importance as an engineer species. The shell of mussels is intensively colonized by microbial organisms that can produce significant quantities of nitrous oxide (N2O), a potent greenhouse gas. To characterize the impacts of climate change on the composition, structure and functioning of microbial biofilms on the shell surface of M. edulis, we experimentally exposed them to orthogonal combinations of increased seawater temperature (20 vs. 23 °C) and decreased pH (8.0 vs. 7.7) for six weeks. We used amplicon sequencing of the 16S rRNA gene to characterize the alpha and beta diversity of microbial communities on the mussel shell. The functioning of microbial biofilms was assessed by measuring aerobic respiration and nitrogen emission rates. We did not report any significant impacts of climate change treatments on the diversity of mussel microbiomes nor on the structure of these communities. Lowered pH and increased temperature had antagonistic effects on the functioning of microbial communities with decreased aerobic respiration and N2O emission rates of microbial biofilms in acidified seawater compared to increased rates in warmer conditions. An overriding impact of acidification over warming was finally observed on N2O emissions when the two factors were combined. Although acidification and warming in combination significantly reduced N2O biofilm emissions, the promotion of aquaculture activities in coastal waters where shellfish do not normally occur at high biomass and density could nonetheless result in unwanted emissions of this greenhouse gas in a near future.

Bacterial density variations of the coastal waters from three marine aquaculture centers in Bali, Indonesia

The highly dynamic nature of marine waters can create unique characteristics for bacterial communities. The purpose of this study was to quantify the number of bacteria present in the beach sand and coastal waters of three marine aquaculture centers in Bali, Indonesia. Two locations that have developed were selected (Patas Village and Candikusuma Village). While an advance centre was located in Sumberkima Village Bay. Sampling was done in March-April 2021. Seawater and beach sand from the three locations were collected and analyzed for total plate count bacteria, Vibrio sp., halotolerant bacteria, rod-shaped gram-negative bacteria and anaerobic facultative bacteria. Sampling of sea water was carried out at 4-5 points around floating net cages and beach sand around the location. The sampling results showed that the total plate count bacteria and halotolerant bacteria in coastal waters from the three locations were less varied. While number of Vibrio sp. in Candikusuma Village lower than the Vibrio sp. in two centre. Rod-shaped gram-negative bacteria were found in advance centre (Sumberkima Village). Sand beach bacteria from Sumberkima Village and Patas Village have similar number of total plate count bacteria, Vibrio sp., halotolerant bacteria and rod-shaped gram-negative bacteria. However, the number of these bacteria were significant different with the same bacterial on the beach sand of Candikusuma Village, except anaerobic facultative bacteria. These results indicate that the bacterial population is influenced by development of aquaculture activities in coastal waters.

Meteotsunamis and other anomalous “tidal surge” events in Western Europe in Summer 2022

We investigate occurrences of anomalous tidal activity in coastal waters of north-west Europe during Summer 2022. Sightings of an anomalous “tidal surge” occurred on 18 June 2022 in Wales, followed by similar observations in Ireland, France, and Spain. Several anomalous long-wave events were also reported in south England and Wales in the morning of 19 July 2022. We analyzed surface and high-altitude air pressure fields, and sea level oscillations for both days. Our detailed analysis reveals that the 18 June events were a series of meteotsunamis, propagating over several countries in Western Europe and triggered by localized pressure perturbations, originating within a low-pressure area over the North Atlantic Ocean. A local analysis of the southern coast of Ireland suggests that Proudman resonance was the determinant mechanism that amplified the meteotsunami traveling eastward in the afternoon of 18 June. A similar analysis of the 19 July events suggests that the tidal surge reported in the UK and anomalous signals recorded in Ireland and France were episodes of seiching triggered by infragravity waves, resonated subharmonically by wind waves. Numerical simulations of the 18 June event were performed with Volna-OP2, which solves the non-linear shallow water equations using a finite volume discretization. The influence of the atmospheric wave velocity on the amplification of the sea surface elevation is analyzed.

Outbreak of marine mucilage in the Sea of Marmara in 2021

An outbreak of marine mucilage in the Sea of Marmara in the spring and summer of 2021 is described. Based on satellite data, an analysis of similar outbreaks in the previous decade was carried out. As shown, the current situation is unique both in terms of the water area coverage and phenomenon duration. The need for comprehensive research is emphasized in order to understand the causes of the occurrence of the marine mucilage and the consequences of its effect on the marine ecosystem and economic activities in coastal waters.

Factors controlling dissolved 137Cs activities in coastal waters on the eastern and western sides of Honshu, Japan

The distributions of dissolved 137Cs in river, nearshore, and offshore waters on the east and west coasts of the Japanese island of Honshu were studied in 2018–2021, 7–10 years after the Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident. On the east side along the north western North Pacific (Fukushima Prefecture), estuarine processes, including desorption from riverine particles and dissolution into pore water from riverine particles that had settled to the seafloor, contributed to the maintenance of high dissolved 137Cs activities in nearshore and offshore waters. A survey and mass-balance calculation in a semi-enclosed estuarine area, the Matsukawa-ura, in the northern part of Fukushima, provided convincing evidence that rivers contributed to the influx of 137Cs to coastal waters. In contrast, the extremely low activities of dissolved and particulate 137Cs in the Tedori River of Ishikawa Prefecture on the western side of Japan along the Japan Sea suggested that inputs of riverine 137Cs made a negligible contribution to the increase of dissolved 137Cs activities in the nearshore and offshore waters. The relatively high dissolved 137Cs activities observed in the offshore waters of the Japan Sea were due to movement of FDNPP-derived 137Cs into the Japan Sea via the Tsushima Warm Current. Mechanisms controlling the distributions of 137Cs activities in coastal waters of the eastern and western sides of Japan therefore differ.

Terrestrial Dissolved Organic Matter Mobilized From Eroding Permafrost Controls Microbial Community Composition and Growth in Arctic Coastal Zones

Climate warming is accelerating erosion along permafrost-dominated Arctic coasts. This results in the additional supply of organic matter (OM) and nutrients into the coastal zone. In this study we investigate the impact of coastal erosion on the marine microbial community composition and growth rates in the coastal Beaufort Sea. Dissolved organic matter (DOM) derived from three representative glacial deposit types (fluvial, lacustrine, and moraine) along the Yukon coastal plain, Canada, were used as substrate to cultivate marine bacteria using a chemostat setup. Our results show that DOM composition (inferred from UV-Visible spectroscopy) and biodegradability (inferred from DOC concentration, bacterial production and respiration) significantly differ between the three glacial deposit types. DOM derived from fluvial and moraine types show clear terrestrial characteristics with low aromaticity (Sr: 0.63 ± 0.02 and SUVA254: 1.65 ± 0.06 L mg C−1 m−1 & Sr: 0.68 ± 0.01 and SUVA254: 1.17 ± 0.06 L mg C−1 m−1, respectively) compared to the lacustrine soil type (Sr: 0.71 ± 0.02 and SUVA254: 2.15 ± 0.05 L mg C−1 m−1). The difference in composition of DOM leads to the development of three different microbial communities. Whereas Alphaproteobacteria dominate in fluvial and lacustrine deposit types (67 and 87% relative abundance, respectively), Gammaproteobacteria is the most abundant class for moraine deposit type (88% relative abundance). Bacterial growth efficiency (BGE) is 66% for DOM from moraine deposit type, while 13 and 28% for DOM from fluvial and lacustrine deposit types, respectively. The three microbial communities therefore differ strongly in their net effect on DOM utilization depending on the eroded landscape type. The high BGE value for moraine-derived DOM is probably caused by a larger proportion of labile colorless DOM. These results indicate that the substrate controls marine microbial community composition and activities in coastal waters. This suggests that biogeochemical changes in the Arctic coastal zone will depend on the DOM character of adjacent deposit types, which determine the speed and extent of DOM mineralization and thereby carbon channeling into the microbial food web. We conclude that marine microbes strongly respond to the input of terrestrial DOM released by coastal erosion and that the landscape type differently influence marine microbes.

Temporal Variations of Submarine Groundwater Discharge into a Tide-Dominated Coastal Wetland (Gaomei Wetland, Western Taiwan) Indicated by Radon and Radium Isotopes

Submarine groundwater discharge (SGD) is evidenced around Taiwan, but the seasonal/temporal changes of SGD have not been fully examined. Here, we report a time-series investigation of SGD into a tide-dominated coastal wetland, the Gaomei Wetland, located to the south of the Da-Chia River’s mouth, western Taiwan, by using environmental tracers (222Rn, 224Raex, 228Ra, δD, and δ18O). Our results showed that regardless of dry and wet seasons, the 222Rn activities in coastal waters were high at low tide but low at high tide. It represents the continuous input of 222Rn-enriched groundwater. However, the 224Raex and 228Ra activities showed seasonal changes with tide conditions. In the dry season, the 224Raex and 228Ra activities in coastal waters were low at low tide but high at high tide; whereas in the wet season, an opposite relation was observed with quite high 224Raex and 228Ra activities in the low-tide waters. Coupled with the lower δD and δ18O values of coastal and pore waters in the dry season, in comparison to those in the wet season, it is suggested that these phenomena probably reflected a seasonal difference in the main SGD component with fresh SGD in the dry season, but saline ones in the wet season. Based on a 222Rn mass balance model, the estimated SGD fluxes into the Gaomei Wetland varied with tidal fluctuations and ranged from 0.2 to 25 cm d−1 and from 0.1 to 47 cm d−1 for the dry and wet seasons, respectively. A slightly high SGD flux occurring during the wet season at spring tide, implied a stronger tidal pumping coupled with a larger hydraulic gradient between land and sea. In this study, we demonstrated that the variation of SGD into the Gaomei Wetland is not only controlled by the seasonal changes of groundwater recharge, but also by the tidal pumping process.

Spatial and temporal profiles of enteric viruses in the coastal waters of Tokyo Bay during and after a series of rainfall events

Recreational activities in coastal waters that are polluted by enteric viruses can result in gastroenteritis etc. In this study, the pollution profiles of enteric viruses were examined in the coastal area of Tokyo Bay, Japan, by collecting 57 water samples from three different depths (0.5 m, 3.0 m, and 5.0 m) during and after a series of heavy rainfall events. Vertically spatial and temporal changes in the concentrations of NoV genogroup I (GI) and genogroup II (GII), pepper mild mottle virus (PMMoV), and Aichi virus (AiV) were determined using quantitative reverse transcription-polymerase chain reaction, while those of the bacterial indicator, Escherichia coli, and F-specific RNA bacteriophages (FRNA phages) were monitored using culture methods. PMMoV was highly abundant (1.4 × 104–6.8 × 106 genome copies/L), whereas the concentrations of the other enteric viruses were relatively low (AiV, 1.3 × 102–2.9 × 104; GI, 2.9 × 10–5.6 × 103; GII, 2.5 × 10–1.2 × 104 genome copies/L). All of the viruses showed lower fluctuations in concentration than E. coli, which increased up to 460-fold after the rainfall event and then decreased over the subsequent two weeks. The maximum vertical difference in E. coli concentration was observed immediately after the rainfall. The E. coli reached the surface and then gradually spread down, whereas the virus concentrations exhibited few fluctuations due to the remaining effects of the previous combined sewer overflows. These findings indicate that viruses have a relatively long retention period over fecal indicator bacteria in this coastal area.

Risk management of coastal water safety for recreational activities: The case of Taoyuan coast

To reduce drowning fatalities and health damage during recreational activities in coastal waters, this paper proposes a dynamic risk management system. Based on the operational definition of risk management, potential risks of coastal recreational activities are first identified as surfzone hydrodynamic and water quality. The safety criteria for each factor are discussed accordingly. The depth-velocity product is adopted to evaluate hydrodynamic safety. Salinity is adopted as a proxy indicator, which could be monitored in real-time, of Escherichia coli colonies in order to avoid the 18–24 h delay for cultivation. Then, technologies for surfzone hydrodynamic and water quality monitoring are developed and implemented as the basis for real-time risk assessment.This system is tested on the north-western coast of Taiwan. The results are discussed as a case study. The results from drifter cluster and miniature wave buoy for mapping the current and waves demonstrates a rotating eddy induced by tidal current. The range of safe water areas could be clearly marked. By applying this dynamic risk management system for coastal recreational activities, an early alert can be provided with the hope to reduce drowning.

Trace metals in two commercial shrimps from southeast Brazil: Baseline records before large port activities in coastal waters

This study presents baseline records of trace metals for two commercial shrimps from the inner continental shelf of southeast Brazil (~22°S). Organisms were sampled in 2004, 10 years before the beginning of large port activities in coastal waters. The concentrations of trace metals in muscle tissues (μg.g−1 w.w.) of Xyphopenaues kroyeri and Artemesia longinaris are as follows: Al: 141.57 and 146.71, Fe: 83.17 and 91.68, Zn: 28.69 and 29.70, Cu: 7.19 and 3.94, Mn: 1.47 and 1.72, Pb: 1.14 and 0.60, V: 0.66 and 0.56, Ni: 0.38 and 0.34, Cr: 0.42 and 0.29, and Cd: 0.15 and 0.14, respectively. Significantly higher concentrations of Cu and Pb were recorded for X. kroyeri. In general, the concentrations are below the maximum permissible limits for metals in fishery/food products, as established by the Brazilian Agency for Sanitary Vigilance (ANVISA), except for Pb and Cr. These baseline records are relevant for future monitoring.

The biogeochemical impact of glacial meltwater from Southwest Greenland

Biogeochemical cycling in high-latitude regions has a disproportionate impact on global nutrient budgets. Here, we introduce a holistic, multi-disciplinary framework for elucidating the influence of glacial meltwaters, shelf currents, and biological production on biogeochemical cycling in high-latitude continental margins, with a focus on the silica cycle. Our findings highlight the impact of significant glacial discharge on nutrient supply to shelf and slope waters, as well as surface and benthic production in these regions, over a range of timescales from days to thousands of years. Whilst biological uptake in fjords and strong diatom activity in coastal waters maintains low dissolved silicon concentrations in surface waters, we find important but spatially heterogeneous additions of particulates into the system, which are transported rapidly away from the shore. We expect the glacially-derived particles – together with biogenic silica tests – to be cycled rapidly through shallow sediments, resulting in a strong benthic flux of dissolved silicon. Entrainment of this benthic silicon into boundary currents may supply an important source of this key nutrient into the Labrador Sea, and is also likely to recirculate back into the deep fjords inshore. This study illustrates how geochemical and oceanographic analyses can be used together to probe further into modern nutrient cycling in this region, as well as the palaeoclimatological approaches to investigating changes in glacial meltwater discharge through time, especially during periods of rapid climatic change in the Late Quaternary.

The building of a management system for marine recreational fisheries in Galicia (NW Spain)

Over the past decades, the nature of the management of marine fisheries in Galicia (NW Spain) has changed substantially. In addition to a powerful commercial fleet and high fisheries dependence of coastal communities, Galicia has a long and strong tradition in marine recreational fisheries, with 60 000 fishers and 4000 boats engaged in this activity in coastal waters. This paper analyses, for the first time, key changes in the management framework of marine recreational fisheries in Galicia by investigating past and current regulations and research initiatives developed so far. Three periods in the management of marine recreational fisheries (1963–1982; 1983–2000; and 2001-present) have been identified. The results show that the management of marine recreational fishing (MRF) moved from a poorly regulated and de facto open access system under the rule of the Spanish administration in the 1980's to a current highly regulated fishery under regional, national and European Union (EU) governments. EU regulations are being fundamental to promote the ecological and socioeconomic sustainability of MRF. However, the lack of scientific data, with only eight papers about MRF in Galicia published in international referred journals, the absence of experts in the field working in the fisheries administration and in research centers, and the lack of strong fishers' organizations are jeopardizing the sustainability of this complex socioecological system in the long term. The development of a strategic plan for MRF in Galicia is needed, including a diagnosis of its current status in relation to other sectors sharing coastal ecosystems, like commercial fisheries, and tourism. Co-management initiatives and adaptive policies favoring both the development of commercial fisheries and the promotion of MRF-based economies to offer new opportunities to local communities are encouraged.

Spatiotemporal variation of alkaline phosphatase activity in coastal waters off Trivandrum

Summary Phosphatase is an extracellular enzyme which releases inorganic phosphate (Pi) from dissolved organic phosphate and indirectly organic carbon as nutrients for aquatic communities. Here, we have examined spatiotemporal variation in total alkaline phosphatase activity (APA) over a short period off Trivandrum, SW India. Sampling was at 50 m water depth at 5, 15, 25 and 45 m for 5 consecutive days at 6 h intervals during post-monsoon season. Total APA and phosphatase producing bacteria (PPB) were estimated along with pertinent environmental parameters. APA increased with depth up to 3.98 µM P h−1 at 45 m. Increase in pigment concentration with depth is responsible for an increase in APA and Pi uptake. There is a marginal increase in APA towards 18–24 h suggesting feeding activities of secondary producers. On the whole, chlorophyll and phaeophytin were responsible for nearly 45 and 55% variation in APA (p

A Distribution of pH and Temperatures in Palopo Coastal Water, South Sulawesi

The construction work in coastal and marine zones has an impact of environmental quality degradation. It causes an environmental pollution which has brought changes in the physical, chemical and biological characteristics of the water environment. Temperature and pH as physical parameters can directly affect marine ecosystem conditions. This research aims to study the pH and temperature conditions and to simulate distributions of these components in Palopo seawater. Direct pH and temperature measurements are provided in eleven stations and implemented on December, 2017. Also, Geographic Information System (GIS) and Surfer 13 software are applied to analyze all obtained data. The results of pH and surface temperature measurements in the Palopo's coastal waters, it showed that surface pH values range from 6 to 6.5. This value is below the quality standards for sea water pH to marine biota around at pH7-8,5, while the surface temperature value is at around 31,5 - 33,3oC. This value has passed the sea water quality standard for marine biota at 28-30oC. A simulation mapping result indicates that the distribution of pH and surface temperature is affected by increased community activity in coastal waters.

Alterations of gene expression indicating effects on estrogen signaling and lipid homeostasis in seabream hepatocytes exposed to extracts of seawater sampled from a coastal area of the central Adriatic Sea (Italy)

Recent evidences suggest that the toxicological effects of endocrine disrupting chemicals (EDCs) involve multiple nuclear receptor-mediated pathways, including estrogen receptor (ER) and peroxisome proliferator-activated receptor (PPAR) signaling systems. Thus, our objective in this study was to detect the summated endocrine effects of EDCs with metabolic activity in coastal waters of the central Adriatic Sea by means of a toxicogenomic approach using seabream hepatocytes. Gene expression patterns were also correlated with seawater levels of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs). We found that seawater extracts taken at certain areas induced gene expression profiles of ERα/vitellogenin, PPARα/Stearoyl-CoA desaturase 1A, cytochrome P4501A (CYP1A) and metallothionein. These increased levels of biomarkers responses correlated with spatial distribution of PAHs/PCBs concentrations observed by chemical analysis in the different study areas. Collectively, our data give a snapshot of the presence of complex EDC mixtures that are able to perturb metabolic signaling in coastal marine waters.

Calibration of a low background gas-flow proportional counter to estimate 234Th activity in coastal waters

This paper relates the calibration of a low background gas-flow proportional counter. This calibration has been used to determine low activity of 234Th in coastal water samples. Two methods were used to prepare calibration samples: Evaporation and Electrodeposition. First method was rejected due to the lack of reproducibility because the different geometry adopted by the drops of tracer once dried on the disk. On the contrary, through the second method, similar efficiencies were obtained in all detectors with an average of 0.401±0.004.In this paper, the whole procedure to obtain 234Th activity in dissolution as well as in particulate matter has been detailed, and all the algorithms needed to calculate activities and efficiencies are shown. Finally, two experiments have been designed in order to validate the calibration of the beta counter and the method to determine 234Th in coastal waters with high concentration of particulate matter.

Spatial management measures for disease mitigation as practiced in Scottish aquaculture

Aquaculture is an increasingly important economic activity in coastal waters. The fluid environment means spatial management is an important tool for protecting fish health. Scottish aquaculture (largely Atlantic salmon) uses a range of different types of area to group farms for different management or reporting purposes related to fish health. Farm Management Areas are defined by local knowledge and used by industry for co-operation among groups of farms, including in the management of sea lice. Disease Management Areas, defined using a simple but robust model, are used by the Scottish Government for control of notifiable diseases. Particle dispersal models are used to assess areas affected by treatment residue around farms, and to manage maximum allowable area biomass for environmental protection. Sophisticated models of sea lice transport have been developed to help inform management of this key parasite. Large regional areas are used for a variety of purposes, such as a policy presumption against new farms covering the entire east and north coasts of Scotland, and five reporting areas for official production statistics. Scottish aquatic environments are shared by many interest groups and spatial management is proving essential for sustainable development by aquaculture and other users.

环境因子对东海原甲藻生长及脲酶活性的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 环境因子对东海原甲藻生长及脲酶活性的影响 DOI: 10.5846/stxb201408251681 作者: 作者单位: 暨南大学水生生物研究中心,暨南大学水生生物研究中心,暨南大学水生生物研究中心,暨南大学水生生物研究中心,暨南大学水生生物研究中心,暨南大学水生生物研究中心 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目(U1133003, 40776078) Effects of environmental factors on the growth and urease activity of the harmful dinoflagellate Prorocentrum donghaiense Author: Affiliation: Key Laboratory of Water Eutrophication and Red-tide Control,Department of Education of Gangdong Province Research centre of Hydrobiology,Jinan University,Key Laboratory of Water Eutrophication and Red-tide Control,Department of Education of Gangdong Province Research centre of Hydrobiology,Jinan University,Key Laboratory of Water Eutrophication and Red-tide Control,Department of Education of Gangdong Province Research centre of Hydrobiology,Jinan University,Key Laboratory of Water Eutrophication and Red-tide Control,Department of Education of Gangdong Province Research centre of Hydrobiology,Jinan University,Key Laboratory of Water Eutrophication and Red-tide Control,Department of Education of Gangdong Province Research centre of Hydrobiology,Jinan University,Key Laboratory of Water Eutrophication and Red-tide Control,Department of Education of Gangdong Province Research centre of Hydrobiology,Jinan University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:以我国东南沿海大规模赤潮原因种东海原甲藻为实验材料,研究了环境因子对其生长及脲酶活性的调控作用。结果表明,东海原甲藻的适宜生长温度为20-25℃,而25℃下脲酶活性最高。在光强2 μmol m-2 s-1 条件下细胞密度显著下降(P < 0.05),但仍能维持较高的脲酶活性(9.405 fmol h-1 个-1)。在盐度20-40范围内,东海原甲藻能够维持快速生长和较高的脲酶活性。氮源组成对东海原甲藻生长无显著影响,但对脲酶活性影响较大。具体而言,东海原甲藻脲酶活性与尿素浓度呈显著正相关关系,而无机氮源NH4+和NO3-对其脲酶活性具有显著的抑制作用,在氮缺乏条件下脲酶活性明显增强。东海原甲藻脲酶活性对环境温度、光照、盐度和营养的响应特征可能是在长期进化中形成的生态适应策略,使其在无机氮源不足时得以转而利用有机氮源,从而在资源竞争中占据有利地位。 Abstract:In the last few decades, the geographic distribution and frequency of harmful algal blooms (HABs) have been increasing worldwide, and have resulted in severe economic losses and ecological disaster. There has been a scientific consensus that there is a positive relationship between occurrences of HABs and increased eutrophication due to human activities in coastal waters. Studies demonstrated that urea has seen wide use in agriculture as a major nitrogen fertilizer in recent years, and consequently, concentrations of urea in aquatic environments have increased dramatically, becoming an important component of dissolved organic nitrogen (DON) in coastal waters. Other studies demonstrated the presence of a positive correlation between the increased input of urea into coastal waters and HABs frequencies. However, the ecological role of urea in triggering HABs, and the mechanism by which it does so (in a species-specific and physiological context in particular), are still unclear. The armored dinoflagellate Prorocentrum donghaiense is a representative HABs-causing alga found in the southeastern coastal waters of China, and has caused serious damage to fisheries and aquaculture facilities, and threatened coastal aquatic ecosystems. This species has shown a wide range of tolerance to light, temperature, and salinity, and is capable of utilizing both inorganic (NO3- and NH4+) and organic (e.g. urea and amino acids) forms of nitrogen (N). Based on our prior study, in which we demonstrated that P. donghaiense exhibits a higher growth rate when grown in media containing urea as the sole N source, compared to those grown with NO3- as the N source, we investigated the effects of environmental factors (temperature, light intensity, and salinity) on the growth of P. donghaiense, and further explored the potential regulating effects of these factors and different forms of N on the activity of urease, a key enzyme involved in the metabolism of urea. The optimal temperatures for P. donghaiense growth were between 20 and 25℃, while the highest urease activity was observed at 25℃. Light was observed to significantly influence urease activity: high urease activity (9.405 fmol h-1 cell-1) was observed even at lower irradiance levels (< 2 μmol m-2 s-1), where the cell density was the lowest. Compared to light and temperature, salinity had the smallest impact on growth and urease activity, i.e., both relatively high growth rates and urease activity were measured at salinities ranging from 20 to 40 psu. Regarding the different effects of different nitrogen resources, P. donghaiense was capable of using all forms of nitrogen provided: NO3-, NH4+, and urea, to meet its growth requirement. However, urease activity, was significantly inhibited by NH4+ and NO3-, but enhanced by the presence of elevated concentrations of urea. More specifically, P. donghaiense exhibited the strongest urease activity three days after inoculation in the urea treatment group, while, in contrast, urease activity in media with NH4+ or NO3- as the sole N source did not change significantly over time and was significantly lower than that observed in the urea-augmented medium. Moreover, we found that NH4+ had a stronger inhibitory effect on the urease activity of P. donghaiense than NO3-. In the N source conversion experiments, urease activity in the NH4+ substrate was still lower than that in NO3- substrate after the addition of equal amount of urea. In addition, urease activity was significantly elevated when ambient nitrogen was deficient. The response of P. donghaiense urease activity and growth rates to the temperature, light, salinity, and nutrient differences observed in this study may reflect an ecological adaptation of P. donghaiense, which allows it to make use of organic nitrogen when inorganic nitrogen sources are insufficient, providing P. donghaiense with a competitive advantage over co-occurring phytoplankton species when the availability of urea is higher than inorganic forms of nitrogen. 参考文献 相似文献 引证文献

Collaborative adaptive management for bigfin squid applied to tourism-related activities in coastal waters of Northeast Taiwan

The bigfin squid Sepioteuthis lessoniana, a commercially important fishery resource and also an object of sightseeing for diving, are under risk situation arising from current management procedure in Taiwan. Significant decline in abundance of bigfin squid and destruction of suitable substrates for spawning of neritic squids in coastal waters of Northeast Taiwan has been noted by local fishermen in recent years. Local divers arbitrarily deployed bamboo clusters as a squid aggregation device, for mating and spawning, in order to restore the abundance of squid. The deployment of the devices was not approved by the government, in particular the fishery authorities. Following conflict and compromises, the bamboo clusters were placed in restricted regions with permission from the local government. However, the interim management measure faced a serious challenge. The fishing activity of fishermen and recreational anglers, who were not consulted for the interim measure, targeted the aggregated squids putting them at risk. To prevent hazards, a theoretical management model was proposed to involve and direct essential stakeholders in conservation and sustainable utilization of the resource. A fishbone diagram and spiral model was created to analyze and illustrate the potential problems. Collaborative management tools were applied to coordinate the participants' duties and responsibilities and build the interrelationships between them. Finally, a modified management model based on adaptive management strategies was developed to cope with the changing situations. This modified management model process might further serve as an example for conservation and management measures of other fisheries resources.