Assessing the effects of Irgarol 1051 on marine phytoplankton populations in Key Largo Harbor, Florida

The antifouling boosting agent Irgarol 1051 is a strong inhibitor of the photosystem II (PSII) with high efficiency/toxicity towards algae. However, because some phytoplankton species are more sensitive to Irgarol than others, its persistent release into the environment could result in adverse changes in the phytoplankton community structure at heavily impacted sites such as marinas. Continuous monitoring in the Florida Keys showed Irgarol concentrations of up to 635 ngL(-1) in the canal system leading to Key Largo Harbor Marina (KLH) with a sharp decrease in concentration at stations offshore from the mouth of the canal. Preliminary phytoplankton community assessments from surface water samples collected in KLH between February and August 2004 showed changes in several phytoplankton species in concordance with the increase of the herbicide concentrations. Typical responses include an increase in the abundance of eukaryotes and Cryptomonas sp. as Irgarol concentrations increase.     

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.     

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.     

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.     

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.     

Photosystem II herbicide pollution in Hong Kong and its potential photosynthetic effects on corals

Photosystem II (PSII) herbicides have been shown to affect the photosynthesis of corals at low, environmentally relevant concentrations. The recent detection of the PSII herbicide Irgarol-1051 in coastal waters of Hong Kong at concentrations above the EC(50) for reduction of photosynthesis of corals prompted further investigation into the extent of PSII herbicide pollution in coral reefs of Hong Kong. Snap-shot and passive samples were taken from coral reef sites and evaluated via HPLC/MS-MS and a novel bioanalytical technique. Low concentrations (less than 10 ng L(-1)) of diuron and atrazine were found at all study sites. Extracts from these samples concentrated by a factor of 10 were found to reduce the photosynthetic yield of zooxanthellae. It appears unlikely that herbicide pollution is a key issue in isolation but may act synergistically with other stressors to reduce the viability of Hong Kong's coral reefs. The study has also demonstrated the feasibility of combining sample extraction techniques with a coral specific bioanalytical technique for a sensitive assessment of risks associated with herbicide exposure in corals.     

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.     

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.     

Assessment of TBT and organic booster biocide contamination in seawater from coastal areas of South Korea

Seawater samples from major enclosed bays, fishing ports, and harbors of Korea were analyzed to determine levels of tributyltin (TBT) and booster biocides, which are antifouling agents used as alternatives to TBT. TBT levels were in the range of not detected (nd) to 23.9 ng Sn/L. Diuron and Irgarol 1051, at concentration ranges of 35–1360 ng/L and nd to 14 ng/L, respectively, were the most common alternative biocides present in seawater, with the highest concentrations detected in fishing ports. Hot spots were identified where TBT levels exceeded environmental quality targets even 6 years after a total ban on its use in Korea. Diuron exceeded the UK environmental quality standard (EQS) value in 73% of the fishing port samples, 64% of the major bays, and 42% of the harbors. Irgarol 1051 levels were marginally below the Dutch and UK EQS values at all sites.     

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.     

Extreme irgarol tolerance in an Ulva lactuca L. population on the Swedish west coast

The herbicide irgarol 1051 is commonly used on ship hulls to prevent growth of algae, but as a component of self-eroding paints it can also spread in the surrounding waters and affect non-target organisms. The effect of irgarol on settlement and growth of zoospores from the marine macro algae Ulva lactuca from the Gullmar fjord on the Swedish west coast was investigated in the present study. The zoospores were allowed to settle and grow in the presence of irgarol, but neither settlement – nor growth inhibition was observed at concentrations of up to 2000 nmol l⁻¹. This is between 10 and 100 times higher than effect concentrations reported earlier for algae. Irgarol also induced the greening effect (4-fold increase in chlorophyll a content) in the settled zoospore/germling population, typical for photosystem II inhibitors like irgarol. This study support previous findings that irgarol constitutes a selection pressure in the marine environment.     

Occurrence of IRGAROL 1051 in coastal waters from Biscayne Bay,Florida, USA

Surface water samples from marinas, commercial ports and open bay areas collected from Biscayne Bay and the Miami River, Florida, USA, were analyzed for the occurrence of IRGAROL 1051 by GC/MS. The anifouling boosting herbicide was found in 80% (46/57) of the samples collected between March 1999 and September 2000. Concentrations within the bay range between non-detected (<1 ppt) and 61 ppt (ng/L) and were generally low compared with levels reported in European or Japanese waters. Aside from the elevated concentrations observed along the Miami River South Fork (61 ppt), the highest concentrations observed in the bay corresponded to marinas with high density of pleasure craft and restricted water circulation. In contrast, occurrence of IRGAROL 1051 along the commercial port or the cruise line terminal was generally lower (<1-2.2 ppt). Concentrations around Coconut Grove Marina were consistently higher (5-12 ppt) than the rest of the bay waters during the whole period of time surveyed.     

Antifouling paint booster biocides in the UK coastal environment and potential risks of biological effects

In the yachting sector of the UK antifouling market, organic biocides are commonly added to antifouling preparations to boost performance. Few data presently exist for concentrations of these compounds in UK waters. In this study the concentrations of tributyltin (TBT) and eight booster biocides were measured before and during the 1998 yachting season. The Crouch Estuary, Essex, Sutton Harbour, Plymouth and Southampton Water were chosen as representative study sites for comparison with previous surveys of TBT concentrations. Diuron and Irgarol 1051 were the only organic booster biocides found at concentrations above the limits of detection. Diuron was measured at the highest concentrations, whilst detectable concentrations of both Irgarol 1051 and diuron were determined in areas of high yachting activity (e.g. mooring areas and marinas). Maximum measured values were 1,421 and 6,740 ng/l, respectively. Lower concentrations of both compounds were found in open estuarine areas, although non-antifouling contributions of diuron may contribute to the overall inputs to estuarine systems. TBT was found to be below or near the environmental quality standard (EQS) of 2 ng/l for all samples collected from estuarine areas frequented by pleasure craft alone, but with much higher concentrations measured in some marinas, harbours and in areas frequented by large commercial vessels. Using the limited published environmental fate and toxicity data available for antifouling booster biocides, a comparative assessment to evaluate the risk posed by these compounds to the aquatic environment is described. TBT still exceeds risk quotients by the greatest margins, but widespread effects due to Irgarol 1051 and less so diuron cannot be ruled out (particularly if use patterns change) and more information is required to provide a robust risk assessment.     

Photosystem II herbicide pollution in Hong Kong and its potential photosynthetic effects on corals

Photosystem II (PSII) herbicides have been shown to affect the photosynthesis of corals at low, environmentally relevant concentrations. The recent detection of the PSII herbicide Irgarol-1051 in coastal waters of Hong Kong at concentrations above the EC₅₀ for reduction of photosynthesis of corals prompted further investigation into the extent of PSII herbicide pollution in coral reefs of Hong Kong. Snap-shot and passive samples were taken from coral reef sites and evaluated via HPLC/MS–MS and a novel bioanalytical technique. Low concentrations (less than 10 ng L⁻¹) of diuron and atrazine were found at all study sites. Extracts from these samples concentrated by a factor of 10 were found to reduce the photosynthetic yield of zooxanthellae. It appears unlikely that herbicide pollution is a key issue in isolation but may act synergistically with other stressors to reduce the viability of Hong Kong’s coral reefs. The study has also demonstrated the feasibility of combining sample extraction techniques with a coral specific bioanalytical technique for a sensitive assessment of risks associated with herbicide exposure in corals.     

Contamination of diuron in coastal waters around Malaysian Peninsular

The use of antifouling paints to the boats and ships is one among the threats facing coastal resources including coral reefs in recent decades. This study reports the current contamination status of diuron and its behaviour in the coastal waters of Malaysia. The maximum concentration of diuron was 285 ng/L detected at Johor port. All samples from Redang and Bidong coral reef islands were contaminated with diuron. Temporal variation showed relatively high concentrations but no significant difference (P > 0.05) during November and January (North-East monsoon) in Klang ports (North, South and West), while higher levels of diuron were detected during April, 2012 (Inter monsoon) in Kemaman, and Johor port. Although no site has shown concentration above maximum permissible concentration (430 ng/L) as restricted by the Dutch Authorities, however, long term exposure studies for environmental relevance levels of diuron around coastal areas should be given a priority in the future.     

Probabilistic risk assessment of common booster biocides in surface waters of the harbours of Gran Canaria (Spain)

The presence of booster biocides in the aquatic environment has been associated with a risk to non-target species due to their proven toxicity. The aim of the present study was to determine the spatial and temporal distribution of common booster biocides in different harbours of the island of Gran Canaria (Spain) and evaluate, by means of a probabilistic risk assessment (PRA), the ecological risk posed by these compounds. With these objectives, a monitoring campaign was conducted between January 2008 and May 2009, collecting a total of 182 seawater samples. Four common booster biocides (TCMTB, diuron, Irgarol 1051 and dichlofluanid) were monitored. Diuron levels ranged between 2.3 and 203 ng/L and Irgarol 1051 between 2.4 and 146.5 ng/L. The ecological risk associated with these levels was always low, however, with probabilities of exceeding the 10th percentile of autotroph toxicity below 3.5%.     

The impact of legislation on the usage and environmental concentrations of Irgarol 1051 in UK coastal waters

In 2001, legislative measures were introduced in the UK to restrict usage of antifouling agents in small (<25 m) vessel paints to dichlofluanid, zinc pyrithione and zineb. This removed the previously popular booster biocides diuron and Irgarol 1051 from the market. To investigate the impact of this legislation, water samples were taken from locations where previous biocide levels were well documented. Results from analyses demonstrate a clear reduction in water concentrations of Irgarol 1051 (between 10% and 55% of that found during pre-restriction studies), indicating that legislation appears to have been effective. Although other booster biocides were screened for (chlorothalonil, dichlofluanid and Sea-Nine 211), they were below the limits of detection (<1 ng/l) in all samples. A survey of chandlers and discussions with legislative authorities supports these results and concurs the removal of Irgarol 1051 based paints from the market using simple regulations at a manufacturer level with little regulation at a retailer level.     

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.     

Permeameter data verify new turbulence process for MODFLOW

A sample of Key Largo Limestone from southern Florida exhibited turbulent flow behavior along three orthogonal axes as reported in recently published permeameter experiments. The limestone sample was a cube measuring 0.2 m on edge. The published nonlinear relation between hydraulic gradient and discharge was simulated using the turbulent flow approximation applied in the Conduit Flow Process (CFP) for MODFLOW-2005 mode 2, CFPM2. The good agreement between the experimental data and the simulated results verifies the utility of the approach used to simulate the effects of turbulent flow on head distributions and flux in the CFPM2 module of MODFLOW-2005.     

Lead in corals: reconstruction of historical industrial fluxes to the surface ocean

Twentieth century environmental lead chronologies for the western North Atlantic, Pacific, and Indian Oceans have been reconstructed from annually-banded scleractinian corals. Measurements of lattice-bound Pb in sequential coral bands reveal temporal changes in surface water Pb concentrations and Pb isotopic distributions. Perturbations are observable in all specimens studied, attesting to global augmentation of environmental Pb by industrialization.In the western North Atlantic, Pb perturbations have occurred in direct response to the American industrial revolution and the subsequent introduction and phasing-out of alkyl Pb additives in gasoline. Surface ocean conditions near Bermuda may be reliably reconstructed from the coral data via a lead distribution coefficient of 2.3 for the species,Diploria strigosa. Based on²¹⁰Pb measurements, a similar distribution coefficient may be characteristic of corals in general. Surface Pb concentrations in the pre-industrial Sargasso Sea were about 15–20 pM. Concentrations rose to near 90 pM by 1923 as a result of metals manufacture and fossil fuel combustion. Beginning in the late 1940's, increased utilization of leaded gasoline eventually led to a peak concentration of 240 pM in 1971, representing an approximate 15-fold increase over background. Surface ocean concentrations are presently declining rapidly (128 pM in 1984) as a result of curtailed alkyl Pb usage. Lead isotopic shifts parallel the concentration record indicating that characteristic industrial and alkyl Pb source signatures have not changed appreciably in time. Industrial releases recorded in the Florida Keys reflect a weaker source and evidence of recirculated Pb (5–6 years old) from the North Atlantic subtropical gyre. An inferred background concentration of 38 pM suggests influence of shelf and/or resuspended inputs of Pb to these coastal waters.In remote areas of the South Pacific and Indian Oceans, industrial signals are fainter and the corals studied much younger than their Atlantic counterparts. Contemporary Pb concentrations implied by coral measurements (assumingK_D = 2.3) are 40–50 pM for surface waters near Tutuila and Galapagos in the South Pacific, and 25–29 pM near Mauritius in the Indian Ocean. A single coral band from Fiji (1920 ± 5yr) implies a pre-industrial surface water concentration of 16–19 pM Pb for the South Pacific. In view of reported surface water measurements and the North Atlantic coral data, the Pacific coral extrapolations may be slightly high. This could be a result of small variations inK_D among different coral genera, or incorporation of diagenetic Pb by corals sampled in coastal environments.