Grant Number: R-91-1-04
Island Wide (Puerto Rico) and U.S. and British Virgin Islands Distribution and Impact study of Triazine constituents in Anti-fouling paints on inshore marine communities, and the Development/Incorporation of Bioassays for Assessment of Marine Pollution
Partners
Ernesto Otero and Kelly Carbery (1)
Richard Owen (2)
James Readman (3)
1 Department of Marine Sciences, University of Puerto Rico, Mayagüez
2 Science Group, Environment Agency, Block 1, Government Buildings, Burghill Road, Westbury-onTrym, Bristol BS10 6BF, UK
3 Plymouth Marine Laboratory, Prospect Place, West Hoe, Plymouth, Devon PL1 3DH, UK
Introduction
Irgarol 1051 (N’-tert-butyl-N-cyclopropyl-6-(methylthio)-1,3,5-triazine-2,4-diamine) is a potent herbicide added to various antifouling paints used mainly on recreational boats. The compound acts via the interruption of photosynthesis via inhibition of electron transport of photosytem II Previous work have found Irgarol worldwide at concentrations up to thousands of ng/L. (reviewed by Konstantinou and Albanis, 2004; Gough et al , 1994; Toth et al , 1996; Zhou et al 1996; Scarlett et al , 1997; Sargent et al 2000; Thomas et al., 2000; Haglund et al. 2001; Albanis et al. 2002; Bowman et al., 2003; Hall Jr. et al., 2005; Owen et al., 2002; Gardinali et al. 2002, 2004; Connelly et al, 2001; Scarlett et al, 1999)
Consequences of Irgarol pollution in marine systems include inhibition of phytoplankton, macroalgae, seagrass and coral primary production This inhibitory effect suggests a profound impact in community structure and coral reef health. Owen et al (2002) found that Irgarol at >100ng/L caused a significant decrease in carbon fixation on Madraciscorals. Bowman et al (2003) suggest that concentrations of 63-250 ng/L may significantly decrease growth and reproduction in algae, concentrations which they commonly found in a UK marina Such inhibition is believed to be unequal among species thus causing competitive disadvantages to some. For example, there is some evidence suggesting that the marine cyanobacteria Synechococcusis more susceptible to Irgarol than certain Cryptophytes (Samora-Ley) while Nystrom et al (2002) suggest that macrophytes are more tolerant than phytoplankton.
Since the effects of Irgarol are concentration dependent, understanding its temporal and spatial distribution is of utmost importance for management of coastal systems A significant number of works are available about Irgarol in marine systems (see above). However, little was known of its presence in US. Caribbean waters, less so far about its temporal and spatial distribution, and potential deleterious effects on Caribbean coastal biota. Earlier findings (Hall Jr. et al, 2005) found limited ecological risk based on a
251ng/L 10thcentile limit for plant effects (the level where effects on 10% of the population were significant). Similarly, Gardinalli et al (2004) concur as they found most of their water samples containing Irgarol <100ng/L, the concentration to reversibly inhibit corals. Macinnis-Ng and Ralph (2003) showed that the seagrass Zostera capricorniwas able to recover from short-term exposure to 10µg/L of Irgarol within 48hrs. However, a much lower threshold (10ng/L) was suggested by Nystrom et al (2002) as a non effect concentration based on phytoplankton and macrophyte inhibition studies At present it is difficult to unequivocally determine exact threshold values for Irgarol concentrations in the tropics without considering long-term effects on various biological components of coastal marine systems The results summarized below address in part the question of the status of Irgarol in US Caribbean Waters, its spatial and to a limited extent its temporal distribution.
SummaryofActivitiesandResults
Sampling for Irgarol 1051 (Ciba-Geigy) was conducted during 2004 Sampling targeted mostly sites characterized by heavy boat traffic such as, ports, marinas and dry stacks in the coast of Puerto Rico, St Thomas and St John The first findings suggest medium concentrations of Irgarol in many locations in PR (lower than 50ng/L) while higher concentrations were found at some locations in St. Thomas. Irgarol concentration was up to 90 ng/L in Red Hook (Vessup Bay) while in Benner Bay was up to 1300 ng/L Finally, lower concentrations were found in St. John´s Cruz and Coral Bay´s (< 2-19). This first year work indicates the presence of potentially biologically deleterious concentrations at various locations, especially in Benner Bay and surrounding areas. These results constituted the first concerted effort to assess Irgarol contamination in the US Caribbean basin and although prompted an important publication (Carbery et al, 2005), did not provide evidence of the temporal and spatial distribution of such contamination
Work on the following year concentrated on better assessing the spatial and temporal patterns of Irgarol 1051 concentration in locations where medium to high concentrations were found previously. Three sites were selected: Benner and Vessup Bays, St. Thomas, and Boquerón Bay, PR Methods of collection and analysis were as per Carbery et al (2005)
In summary, samples were collected at multiple locations in all three sites which permitted a better look to the spatial distribution of Irgarol. Results for Vessup Bay indicate a slightly higher concentration within the central portion of American Yatch Habour Marina as compared to samples collected across the navigation channel (Figure 1). Irgarol concentration dropped relatively fast towards the mouth of the bay from values of 30-49 to 2-17 ng/L Data for Benner Bay confirmed the high concentrations of Irgarol (up to 668 ng/L) found in the previous year, but not as extreme (Figure 1). Within 1 km from the inner bay, Irgarol dropped to 26 ng/L, a concentration that still may be considered significant, as chronic exposure effects are not well documented These results validate our previous work and underscore the robustness of targeted sampling to detect areas of significant contamination while minimizing costs of gunshot approaches.
A series of up to 21 stations were sampled in three occasions in the immediacy of the Nautical Club, Boquerón Bay, in order to confirm previous results, the dispersion and temporal changes within a relatively short period of time (days; Figure 2) The results for the location sampled in the previous year (11-32ng/L) were very similar to those for the second year (9-26 ng/L) The dispersion pattern during the three sampling dates is similar in that low concentrations of Irgarol were found just 100m westward from the Nautical Club (a seaward decreasing trend) Some differences were observed between sampling days and attributed to tidal differences since wind conditions were calm throughout this part of the work. The stage of tide was estimated using WXTide32 software and showed that, during the first two samplings, tides were at a high stage (or reaching a high stage) while the third day (Nov 10) the tide was at the lowest. It is during this latter date slightly
Figure 2. Spatial and temporal distribution of Irgarol in Boquerón Bay. Numbers represent ng/L of the contaminant Shading is a relative scale of contamination. Red numbers are considered high, yellow intermediate and blue low values. Outer station was used as a low end value and is about 1.2 km to the west
higher concentrations were found somewhat farther to sea while the site with the overall highest Irgarol concentration (associated to an inland marina) reached its lowest. Data from the time series of Boquerón indicate a strong dilution of Irgarol due to extant marine currents with a strong tidal component driving Irgarol flow seaward from coastal sources
ExtendedEfforts
Additional work have commenced in which the feasibility for a low budget running seawater system to maintain and incubate coral nubbins is being tested These facilities will become the basis for additional experiments on the effects of Irgarol and similar compounds. Results indicate that survival of colonies of Occulinadiffusais high after manipulation Whole colonies or nubbins were transplanted during January 2007 and kept under intermittently running seawater (timers controlled a cycle of 18 hours running water and 6 hours still water) with aeration. Addition of UV pretreatment of inflowing water and 2-3 °C cooling of running water is being tested at present to maintain survivability during the warmer months of the year. This system will allow testing weeks-long exposure effects on local coral species and hopefully allow expand efforts towards experimentation with corals such as Acroporaprolifera , which are close to those managed by regulation at present.
Insummary,ourwork:
Indicates a significant presence of Irgarol in PR and USVI waters specially associated to sites heavily used by boaters;
Points out those locations with low water currents, thus long turnover of water, are potentially sites where Irgarol (as any other contaminant) may become highly concentrated, depending on access to the compound and boat density.
Demonstrates the presence of Irgarol (at low levels) in areas adjacent to National Parks (Coral Bay, St John), which will probably be subjected to increased boating activities; thus increased exposure to Irgarol
Found in Benner Bay the highest Irgarol concentrations within the study Part of Cas Cay and Mangrove Lagoon Reserve falls within this significantly polluted area.
Showed marginally high concentrations of Irgarol in Puerto Rico and mostly associated to marinas. A newer inland marina within Boquerón Bay is a significant source of Irgarol at levels reported to be deleterious to coral symbionts
Evidenced that low concentration ( i.e. 4-20 ng/L) of Irgarol was commonly observed in the places targeted The effects of spill-over from sources of Irgarol into protected or unprotected areas are uncertain as limited work is available on effects of chronic exposure to low concentrations of Irgarol
Suggests sales of Irgarol containing antifouling paints should increase in PR as the market expands, therefore, the presence of Irgarol in coastal waters of PR will be more
common in the future unless restriction to its used are put in place or alternative products are introduced to the market.
Recommendations
Our findings indicate the need for:
Studies on the effects of low level Irgarol contamination on local species. Chronic effects may be non-lethal but reduce competitiveness of some species by decreasing productivity and potentially triggering cascading events
Managers should consider the location of marinas with respect to adjacent protected habitats and resources as these are a source of Irgarol (or other contaminants).
The use of highly toxic compounds in antifouling paints should be avoided
StudentsBenefitted
Kelly K. Carbery played a vital role in the success of this work. With the help of the collaborators he collected samples and analyzed samples In addition, he was principal author in a manuscript published as a result of this work. The title of his MS. Thesis is: ACaseStudyofIrgarolContaminationinCoastalEnvironments:theCaseof CaribbeanWaters.
Presentations
KellyK Carbery, , Ernesto Otero, Richard Owenand James Readman Island Wide (Puerto Rico), U.S. and British Virgin Islands Distribution and Impact Study of Triazine Constituents in Anti-fouling Paints on Inshore Marine Communities, and the Development/Incorporation of Bioassays for Assessment of Marine Pollution First Annual Symposium for Coastal and Marine Applied Research. 2 Sep 2005. Mayagüez, PR
ErnestoOtero , Kelly K. Carbery, Jr., Richard Owen, James Readmanm, and Trish Frickers Contamination of Caribbean Coastal Waters by the Antifouling Herbicide Irgarol 1051. Second Annual Symposium for Coastal and Marine Applied Research. 5 Oct 2006 Mayagüez, PR
Publication
Carbery, K., R. Owen, T. Frickers, E. Otero and J. Readman. 2006. Contamination of Caribbean Coastal Waters by the Antifouling Herbicide Irgarol 1051. Mar. Poll. Bull. 52: 635-644
References
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