The relationship of Irgarol and its major metabolite to resident phytoplankton communities in a Maryland marina, river and reference area

The objectives of this study were to: (1) measure water column concentrations of Irgarol 1051 and its major metabolite GS26575 annually (2004-2006) during mid-June and mid-August at 14 sites in a study area comprised of three sub-regions chosen to reflect a gradient in Irgarol exposure (Port Annapolis marina, Severn River and Severn River reference area); (2) use a probabilistic approach to determine ecological risk of Irgarol and its major metabolite in the study area by comparing the distribution of exposure data with toxicity-effects endpoints; and (3) measure both functional and structural resident phytoplankton parameters concurrently with Irgarol and metabolite concentrations to assess relationships and determine ecological risk at six selected sites in the three study areas described above. The three-year summer mean Irgarol concentrations by site clearly showed a gradient in concentrations with greater values in Back Creek (400-500 ng/L range), lower values in the Severn River sites near the confluence with Back Creek (generally values less than 100 ng/L) and still lower values (<10 ng/L) at the Severn River reference sites at the confluence with Chesapeake Bay. A similar spatial trend, but with much lower concentrations, was also reported for GS26575. The probability of exceeding the Irgarol plant 10th centile of 193 ng/L and the microcosm NOEC (323 ng/L) suggested high ecological risk from Irgarol exposure at Port Annapolis marina sites but much lower risk at the other sites. There were no statistically significant differences among the three site types (marina, river and reference) with all years combined or among years within a site type for the following functional and structural phytoplankton endpoints: algal biomass, gross photosynthesis, biomass normalized photosynthesis, chlorophyll a, chlorophyll a normalized photosynthesis and taxa richness. Therefore, based on the above results, Irgarol adverse effects predicted from the plant 10th centile and the microcosm NOEC in the high Irgarol exposure area (Back Creek/Port Annapolis marina) were not confirmed with the actual field data for the receptor species (phytoplankton). These results also highlight the importance of unconfined field studies with a chemical gradient in providing valuable information regarding the responses of resident phytoplankton to herbicides.     

Monitoring of Irgarol 1051 concentrations with concurrent phytoplankton evaluations in East Coast areas of the United States

The objectives of this study were to measure: (1) Irgarol and GS26575 (major metabolite) during the peak 2004 boating season at selected marinas and reference areas in the Carolinian Zoogeographic Province of the Eastern United States; (2) Irgarol and GS26575 at selected stations during the summer months in the Back Creek/Severn River area in Maryland in 2003 and 2004; and (3) structural and functional characteristics of resident phytoplankton communities concurrently with Irgarol and GS26575 monitoring in Back Creek/Severn River area. Irgarol concentrations from 14 marinas in the Carolinian Province ranged from non-detectable (<1 ng/L) to 85 ng/L; concentrations were less than 16 ng/L at all reference sites. The probability of exceeding the plant 10th centile for Irgarol (251 ng/L) was less than 0.6% for all marinas and 0.01% for all reference areas. These data suggest low ecological risk from Irgarol exposure for both marina and reference areas in the Carolinian Province. Irgarol concentrations ranged from 5 ng/L at the Severn River reference site to 1,816 ng/L in Port Annapolis marina during the two year study. Ecological risk from Irgarol exposure was high for the Port Annapolis marina sites based on a probability of exceeding the plant 10th centile. However, risk was low for Severn River and Severn River reference sites. Functional and structural measures of resident phytoplankton communities in the Back Creek and Severn River did not suggest that these target species are impaired in the Port Annapolis marina area where probabilistic analysis predicted adverse effects from Irgarol exposure.     

Antifouling biocides in water and sediments from California marinas

Irgarol 1051 is a common antifouling biocide and is highly toxic to non-target plant species at low ng/L concentrations. We measured up to 254 ng/L Irgarol in water and up to 9 ng/g dry weight Irgarol in sediments from Southern California recreational marinas. Irgarol’s metabolite, M1, concentrations were up to 62 ng/L in water and 5 ng/g dry weight in sediments. Another antifouling biocide, diuron, reached up to 68 ng/L in water and 4 ng/g dry weight in sediments. The maximum Irgarol concentrations in water were greater than the Irgarol concentration recommended as the plant toxicity benchmark (136 ng/L), suggesting that Irgarol concentrations may be high enough to cause changes in phytoplankton communities in the sampled marinas. Irgarol concentrations measured in sediments were greater than calculated Environmental Risk Limits (ERLs) for Irgarol in sediments (1.4 ng/g). Antifouling pesticide accumulation in sediments may present a potential undetermined risk for benthic organisms.     

Occurrence and transport of Irgarol 1051 and its major metabolite in coastal waters from South Florida

Irgarol 1051, a boosting antifouling agent often used to supplement copper based paints was found in surface waters from South Florida at stations collected from the Miami River, Biscayne Bay and selected areas of the Florida Keys. Concentrations of the herbicide ranged from below the method detection limit (1 ng/L) to as high as 182 ng/L in a canal system in Key Largo. The herbicide was present at 93% of the stations and often found in conjunction with its descyclopropyl metabolite (M1) previously reported to be the major degradation product of Irgarol under natural environmental conditions. The 90th percentile concentration calculated for all South Florida samples was 57.6 ng/L. Based on available data on the toxicity of Irgarol to algae and coral, only two stations (approximately 3%) ranked above the LC50 of 136 ng/L reported for the marine algae Naviculla pelliculosa and above the 100 ng/L level reported to reversibly inhibit photosynthesis of intact corals. However, a basic dissipation model for Irgarol using the Key Largo Harbor station as a point source indicated that concentrations of the herbicide decreased rapidly and concentrations below the MDL are observed within 2000 m of the source. No major coral based benthic habitats are documented for all the stations surveyed at distances that Irgarol may pose a substantial risk. However, other types of submerged vegetation like seagrasses are common around the marinas and the effects of Irgarol to such endpoints should be investigated further.     

Inhibition of coral photosynthesis by the antifouling herbicide Irgarol 1051

International regulation of organotin compounds for use in antifouling paints has led to the development and increased use of replacement compounds, notably the s-triazine herbicide Irgarol 1051. Little is known about the distribution of Irgarol 1051 in tropical waters. Nor has the potential impact of this triazine upon photosynthesis of endosymbiotic microalgae (zooxanthellae) in corals been assessed. In this study Irgarol 1051 was detected in marinas, harbours and coastal waters of the Florida Keys, Bermuda and St. Croix, with concentrations ranging between 3 and 294 ng 1(-1). 14C incubation experiments with isolated zooxanthellae from the common inshore coral Madracis mirabilis showed no incorporation of H14CO3- from the sea water medium after 4-8 h exposure to Irgarol 1051 concentrations as low as 63 ng 1(-1). Reduction in net photosynthesis of intact corals was found at concentrations of l00 ng 1(-1) with little or no photosynthesis at concentrations exceeding 1000 ng 1(-1) after 2-8 h exposure at all irradiances. The data suggest Irgarol 1051 to be both prevalent in tropical marine ecosystems and a potent inhibitor of coral photosynthesis at environmentally relevant concentrations.     

MELIMEX,an experimental heavy metal pollution study: Effects of increased heavy metal loads on phytoplankton communities

Long-term impacts of increased metal loading (Hg, Cu, Cd, Zn and Pb) on phytoplankton communities of large limno-corrals (diameter 12 m, depth 10 m) were studied. Increased metal concentrations initially lowered phytoplankton biomass, as well as species number and photosynthetic activity of phytoplankton. They caused changes in metal speciation and shifts in phytoplankton community structure, favoring less susceptible species. Although adaptation was not sufficient to completely prevent the metal-induced depression of photosynthesis, due to depressed zooplankton grazing, at the end of the experiment even higher phytoplankton densities were observed in the metal-loaded corrals than in the control.     

A retrospective analysis of contamination and periphyton PICT patterns for the antifoulant irgarol 1051, around a small marina on the Swedish west coast

Irgarol is a triazine photosystem II (PSII) inhibitor that has been used in Sweden as an antifouling ingredient since the 1990s. Early microcosm studies indicated that periphyton was sensitive to irgarol at concentrations regularly found in harbours and marinas. However, field studies of irgarol effects on the Swedish west coast in 1994, using the pollution-induced community tolerance (PICT) approach, failed to detect any effects of the toxicant in the field. A PICT study involves sampling of replicate communities in a gradient of contamination, and a comparison of their community tolerance levels, with an increase being an indication that sensitive species have been eliminated and replaced by more tolerant ones. Typically, short-term assays are used to quantify the community tolerance levels. Later PICT studies in the same area over a 10 year period demonstrate that irgarol tolerance levels have increased, although the contamination pattern has been stable. Our results support the hypothesis that that the PICT potential was low initially, due to a small differential sensitivity between the community members, and that a persistent selection pressure was required to favour and enrich irgarol-tolerant species or genotypes.     

Occurrence of Irgarol 1051 and its major metabolite in Maryland waters of Chesapeake Bay

Irgarol and its major metabolite (GS26575) were measured in Maryland waters of Chesapeake Bay: (1) in and near 10 marinas, a mainstem Bay site and two Severn River locations during a general survey in July and December of 2002; (2) at various sites in the Port Annapolis Marina and the Severn River area during March of 2002 before the boating season began; and (3) during July (peak boating season) in the same Port Annapolis Marina and Severn River sites area during both an ebb and flood tide. Irgarol concentrations ranged from 1.82 ng/l at the mid-Bay site to 585 ng/l in Port Annapolis marina during the July and December general survey. An Irgarol 90th centile of 239 ng/l was reported for the 10 marina sites, two Severn River sites and one mainstem site sampled during the general survey conducted in July and December. Temporal analysis of all pooled data showed that 90th centiles were over seven times higher in July when compared to December. A comparison of Irgarol concentrations at 12 sites in the Port Annapolis marina and Severn River area during both an ebb and flood tide in July showed no consistent trend with tidal cycle by site although significant reductions in concentrations were reported with distance from the three Port Annapolis marina sites. Ecological risk from Irgarol exposure was judged to be low for most Chesapeake Bay sites sampled. Possible exceptions were Port Annapolis marina, Severn River sites in close proximity to this marina and Chesapeake Harbor marina where Irgarol concentrations exceeded a conservative effects threshold during the peak boating season in July. Ecological risk from GS26575 exposure was low for all sites.     

Phytoplankton distribution and productivity in a highly turbid, tropical coastal system (Bach Dang Estuary, Vietnam)

Phytoplankton diversity, primary and bacterial production, nutrients and metallic contaminants were measured during the wet season (July) and dry season (March) in the Bach Dang Estuary, a sub-estuary of the Red River system, Northern Vietnam. Using canonical correspondence analysis we show that phytoplankton community structure is potentially influenced by both organometallic species (Hg and Sn) and inorganic metal (Hg) concentrations. During March, dissolved methylmercury and inorganic mercury were important factors for determining phytoplankton community composition at most of the stations. In contrast, during July, low salinity phytoplankton community composition was associated with particulate methylmercury concentrations, whereas phytoplankton community composition in the higher salinity stations was more related to dissolved inorganic mercury and dissolved mono and tributyltin concentrations. These results highlight the importance of taking into account factors other than light and nutrients, such as eco-toxic heavy metals, in understanding phytoplankton diversity and activity in estuarine ecosystems.     

南水北调中线干渠浮游植物群落时空格局及其决定因子

为了解南水北调中线干渠浮游植物群落的时空格局,自2018年8月开始分4个季度对干渠沿程的11个样点进行采样调查,同步开展水环境调查;共检出浮游植物7门83属145种,物种丰富度上,硅藻种类数最多,绿藻和蓝藻分别占第2和第3位,且春季>秋季>冬季>夏季;优势种包括极小曲丝藻(Achnanthidum minutissimum)、桥弯藻(Cymbella sp.)、空星藻(Coelastrum sphaericum)、衣藻(Chlamydomonas sp.)等(优势度Y>0.02);全年叶绿素a浓度为(4.09±2.89)μg/L,细胞密度为(6.79±7.15)×10⁶cells/L,夏季细胞密度显著高于其他季节,以绿藻、蓝藻为主,其他季节以硅藻、绿藻为主;空间上,细胞密度从南到北呈递增趋势,穿黄工程后显著高于穿黄工程前;RDA与多元线性回归分析显示:水温和营养盐是影响群落结构的关键因素,其次是流量和流速,这些因子成为群落时空格局的决定因子;NMDS与聚类分析显示:时间变化对于群落结构产生的影响比空间变化更为显著.本研究确认了跨流域长距离输水的中线干渠中浮游植物群落的显著时空异质性;鉴于流速、流量对群落的决定作用,建议在输水管理中加强生态调度技术研究,以调控浮游植物群落,保障水质稳定.     

Long-term changes in physical and chemical conditions of nutrient-poor lakes along a latitudinal gradient: is there a coherent phytoplankton community response?

To evaluate climate and atmospheric deposition induced physical and water chemical changes and their effects on phytoplankton communities, we used complete time series (14 years, monthly measurements during the growing season) of 18 physical and chemical variables and phytoplankton data from 13 nutrient-poor Swedish reference lakes along a latitudinal gradient. We found numerous strong significant changes over time that were most coherent among lakes for sulfate concentrations, conductivity, calcium, magnesium, chloride, potassium, water color, surface water temperature and the intensity of thermal stratification. Despite these pronounced coherent physical and water chemical changes over Sweden, the phytoplankton biomass and species richness of six phytoplankton groups, measured at the same time as the water chemical variables, showed only few and weak significant changes over time. The only coherent significant change over Sweden, occurring in seven lakes, was observed in the species richness of chlorophytes. The number of chlorophyte taxa significantly declined over Sweden. Using a partial least square model for each lake, we attributed the decline primarily to an increase in water temperatures and water color, which were among the most important variables for the model performance of each lake. All other taxonomic groups were driven primarily by non-coherent changes in nutrient concentrations, pH and probably also non-coherent grazing pressure. We concluded that coherent phytoplankton responses can only be achieved for taxonomic groups that are driven primarily by coherent physical/chemical changes. According to our study, chlorophytes belong to such a group, making them possible global change indicators. Our findings give new insights into global change effects on different phytoplankton taxonomic groups in nutrient-poor lakes.     

Ecological risk of Irgarol 1051 and its major metabolite in coastal California marinas and reference areas

The objective of this study was to use a probabilistic approach to determine the ecological risk of Irgarol and its major metabolite (GS26575) in coastal California marinas and reference areas by using monitoring data collected during the summer of 2006. Distributions of environmental exposure data were compared with the distribution of plant species response data from laboratory toxicity studies and the no observed effect concentration (NOEC) from a microcosm study to quantify the likelihood and significance of ecological risk. Toxicity testing indicates plants are much more sensitive to Irgarol than animals; therefore, the conservative effects benchmark used to characterize risk was the plant 10th centile for both Irgarol (193 ng/L) and GS26575 (5622 ng/L). In addition, the microcosm NOEC of 323 ng/L was also used to characterize risk. Irgarol concentrations from 15 California marinas ranged from 1.45 to 339 ng/L while GS26575 concentrations ranged from non-detected to 74 ng/L. The probability of exceeding the Irgarol plant 10th centile of 193 ng/L for 15 marinas sampled in coastal California in 2006 was 7.3% while the probability of exceeding the microcosm NOEC of 323 ng/L was even lower (5.5%). In general, this probability of exceedence for either effects benchmark and subsequent ecological risk is considered to be low for these marinas as only one marina (Kings Harbor marina in Redondo Beach) had measured concentrations of Irgarol exceeding 193 ng/L. Irgarol exposure is concentrated within marinas and ecological risk from Irgarol exposure in adjoining reference areas was judged to be very low. Ecological risk from GS26575 exposure was also low in both marina and reference areas in California.     

Contamination of the coastal waters of Bermuda by organotins and the triazine herbicide Irgarol 1051.

A study of the distribution of the 'booster' biocide 2-methylthio-4-tert-butylamino-6-cyclopropyl amino-s-triazine (Irgarol 1051) was carried out in the coastal waters of Bermuda. Irgarol 1051 concentrations (as determined by GC/MS) up to 590 ng l-1 have been measured within Hamilton Harbour. The data presented herein unequivocally demonstrate contamination of the coastal system of Bermuda by Irgarol 1051. Concurrently, TBT concentrations were measured and results indicate that levels are falling through legislated changes in antifouling treatments, from 220 ng l-1 in 1990 to < 20 ng l-1 (as Sn) by 1995, in the open water area of Hamilton Harbour. Concentrations of TBT immediately offshore from a boatyard were found to be > 600 ng l-1 (Sn), indicating continuing release due to painting operations and sediments in the area.     

贵州百花湖麦西河河口浮游植物群落结构及与环境因子关系

2009年7月至2010年6月,以每月一次的频率对百花湖(水库)麦西河河口浮游植物群落结构和环境因子进行调查.监测到浮游植物66种(属),浮游植物主要由绿藻、硅藻和蓝藻组成,夏秋季湖泊假鱼腥藻(Pseudanabaena limnetica)为优势浮游植物,而冬春季梅尼小环藻(Cyclotella meneghinia...     

Toxicities of antifouling biocide Irgarol 1051 and its major degraded product to marine primary producers

Irgarol 1051 (2-methythiol-4-tert-butylamino-6-cyclopropylamino-s-triazine) is an algaecide commonly used in antifouling paints. It undergoes photodegradation which yields M1 (2-methylthio-4-tert-butylamino-6-amino-s-triazine) as its major and most stable degradant. Elevated levels of both Irgarol and M1 have been detected in coastal waters worldwide; however, ecotoxicity effects of M1 to various marine autotrophs such as cyanobacteria are still largely unknown. This study firstly examined and compared the 96 h toxicities of Irgarol and M1 to the cyanobacterium Chroococcus minor and two marine diatom species, Skeletonema costatum and Thalassiosira pseudonana. Our results suggested that Irgarol was consistently more toxic to all of the three species than M1 (96 h EC50 values: C. minor, 7.71 microug L(-1) Irgarol vs. > 200 microg L(-1) M1; S. costatum, 0.29 microg L(-1) Irgarol vs. 11.32 microg L(-1)M1; and T. pseudonana, 0.41 microg L(-1) Irgarol vs. 16.50 microg L(-1)M1). Secondly, we conducted a meta-analysis of currently available data on toxicities of Irgarol and M1 to both freshwater and marine primary producers based on species sensitivity distributions (SSDs). Interestingly, freshwater autotrophs are more sensitive to Irgarol than their marine counterparts. For marine autotrophs, microalgae are generally more sensitive to Irgarol than macroalgae and cyanobacteria. With very limited available data on M1 (i.e. five species), M1 might be less toxic than Irgarol; nonetheless this finding warrants further confirmation with additional data on other autotrophic species.     

四种浮游植物生物量计算方法的比较分析

浮游植物是水生生态系统中重要的初级生产者,其生物量是反映其现存量的关键指标.本文利用具有3个处理组的围隔实验中的浮游植物数据,对文献中常见的计算浮游植物种群生物量和群落生物量的4种方法:标准法、细分法、粗分法和资料法进行比较,并分析采用这4种不同方法得到的浮游植物生物量与叶绿素a浓度的相关性.结果表明:粗分法是计算浮游植物生物量的高效方法,能够保证准确度和节省时间;提高浮游植物生物量计算准确度不是影响浮游植物生物量与叶绿素a浓度相关性显著程度的关键.通过比较剔除稀有种(生物量不超过群落生物量5%的种类)前后浮游植物生物量的差异,发现忽略稀有种会导致种类均匀度较高的浮游植物群落生物量严重偏低,建议浮游植物生物量的计算不能一概忽略稀有种.     

Contamination of Caribbean coastal waters by the antifouling herbicide Irgarol 1051

Irgarol 1051 is a s-triazine herbicide used in popular slime-resistant antifouling paints. It has been shown to be acutely toxic to corals, mangroves and sea grasses, inhibiting photosynthesis at low concentrations (>50 ng l(-1)). We present the first data describing the occurrence of Irgarol 1051 in coastal waters of the Northeastern Caribbean (Puerto Rico (PR) and the US Virgin Islands (USVI)). Low level contamination of coastal waters by Irgarol 1051 is reported, the herbicide being present in 85% of the 31 sites sampled. It was not detected in water from two oceanic reference sites. In general, Irgarol 1051was present at concentrations below 100 ng l(-1), although far higher concentrations were reported at three locations within Benner Bay, USVI (223-1,300 ng l(-1)). The known toxicity of Irgarol 1051 to corals and sea grasses and our findings of significant contamination of the Northeastern Caribbean marine environment by this herbicide underscore the importance of understanding, more fully, local and regional exposure of reef and sea grass habitats to Irgarol 1051 and, where necessary, implementing actions to ensure adequate protection of these important ecosystems.     

武汉月湖水生植被重建过程中浮游植物的动态变化

2004年12月-2005年5月武汉市月湖水生植被重建过程中,对浮游植物进行逐月调查.结果表明,在营养盐浓度较高的条件下,浮游植物仍保持较低的生物量和密度,浮游植物的生长与温度保持一定的相关性,但与湖水营养盐浓度并不存在相关关系.菹草和伊乐藻能使水体的透明度保持较高的状态.浮游植物主要由隐藻和硅藻组成,能形成水华的一些常见种类并未随温度升高而出现,可能与这两种沉水植物的存在改变了浮游植物的群落结构有关.因此,在水温较低的冬季和春季进行水生植被重建是富营养化湖泊治理的有效途径.     

Seasonal variability in the concentrations of Irgarol 1051 in Brighton Marina,UK; including the impact of dredging

Variations in Irgarol 1051 concentrations in the UK's largest marina at Brighton were determined regularly over a period of one year. Aqueous concentrations ranged from <1 to 960 ngl(-1) with highest mean concentrations generally associated with berths for larger vessels and with the main channels. Temporally, highest concentrations were recorded in November through to January and were probably associated with maintenance of vessels in an adjacent boatyard. Elevated levels were also encountered at the beginning of the season, coinciding with the introduction of newly antifouled vessels. Increased concentrations also followed dredging, possibly through re-mobilisation of Irgarol 1051. No correlations were found between dissolved Irgarol 1051 concentrations and pH, temperature or salinity. With the exception of sporadically high concentrations recorded for water samples (probably taken in close proximity to recently antifouled vessels), concentrations rarely exceeded the no observed effect concentration for marine periphyton of 63 ngl(-1). Concentrations of Irgarol 1051 in sediments sampled from the marina ranged from <1 to 77 ngg(-1). Apparent distribution coefficients (K(d)) calculated from sedimentary and aqueous samples (collected simultaneously) are generally within the range of K(d)'s reported from laboratory experiments.