Antifouling paint particles in soils: toxic impact that goes beyond the aquatic environment.

Antifouling paint particles (APPs) originate from vessel maintenance and cleaning activities and their potentially toxic components are found at high concentrations in nearby soils, yet no studies have investigated their toxicity to soil organisms. We investigated the effects of exposure to soils containing APPs on the mortality, biomass, and reproductive performance of the earthworm Eisenia andrei. Earthworms were exposed to contaminated soil from a boatyard and non-contaminated soils treated with different concentrations of APPs (0.01, 0.14 and 1.50%, w/w) for 56 days. An ecological risk assessment using a Hazard Quotient (HQ) was also carried out. Exposure to contaminated soils reduced worm survival, biomass, and reproductive performance and these effects were concentration-dependent. The HQ was high in soil samples with APPs in both acute and chronic tests, and copper contributed the most to the HQ. Copper, zinc, and lead had the highest concentrations and exceeded the Brazilian legal limits. A principal component analysis (PCA) was performed and showed that biomass and number of juveniles parameters was associated with the metals Cu, Sn and Zn, while the mortality parameter had no association with any analyzed metal. These findings highlighted that the synergistic effects of compounds present in the APPs, such as the booster biocides DCOIT, and metal mixtures should not be overlooked. We conclude that soils contaminated with APPs are toxic to earthworms. This reveals that the ecological impact of APPs goes beyond effects on aquatic environments, compromising key organisms of edaphic ecological processes.

Potential ecotoxicity of metals leached from antifouling paint particles under different salinities.

Antifouling paint particles (APPs) are residues generated during maintenance of vessels. In boat maintenance areas of South America, waste generation and disposal are not completely regulated. Therefore, APPs can enter into the aquatic environment and act as a source of contamination by metals and other biocides. Thus, the aim of the present study was to evaluate the potential ecotoxicity of the metal mixture present in APPs leached under different salinities. Therefore, the copepod Acartia tonsa was exposed to different concentrations of a leachate solution prepared by the addition of APPs (1.25g/L) in artificial saline water (salinities 5, 15 and 30). Thereafter, complexing agents (EDTA and sodium thiosulfate) were added to the experimental media in order to evaluate metal influence in APPs toxicity. APPs leachate solutions were very toxic to A. tonsa, reaching an estimated LC50 of 1% at salinities 5% and 15%, and 2% at salinity 30. The addition of the chelators in leachate solutions showed that metals are the major responsible compounds for the observed toxicity. Moreover, results from the calculated toxic units suggested a slightly synergic effect between Cu and Zn in the paint formulation. A metal speciation modelling showed that Zn was predominant as a free ion at all salinities, therefore, explaining the high leachate toxicity. Furthermore, the release of Zn was observed more at lower salinities, whereas Cu was observed at higher salinities. APPs are frequently released in estuarine systems, under conditions of salinity gradients. Therefore, navigated estuaries might be under the threat of this neglected residue.

Size, season and origin of gastropods matter in imposex assessments.

Through controlled exposure to tributyltin (TBT), the effects of season, size, and population origin were evaluated on imposex incidence in Stramonita brasiliensis. Four experiments were carried out with organisms collected from three different sites on the Brazilian coast (Torres - Rio Grande do Sul, Farol de Santa Marta - Santa Catarina, and Aracruz - Espírito Santo). S. brasiliensis were anesthetized, sexed, measured, classified by size in small (< 30 mm), medium (≥ 30 to ≤ 40 mm), or big (> 40 mm) and injected in the foot muscle with 0.5 µg g-1 of TBT. Organisms were maintained during one month in aquariums with clear marine water under controlled laboratory conditions. One month after injection, the imposex assessments showed that the population from the southeast (tropical) region was more sensitive to TBT than the population from the south of Brazil (the temperate region). A greater sensitivity in the small and medium categories was observed. Females were also more susceptible to TBT when exposed during their reproductive period. Thus, the present study highlighted the need to ensure that intrinsic biological factors related to organisms are considered in such biomonitoring studies to avoid misinterpretation of results.

Microplastic in clams: An extensive spatial assessment in south Brazil.

Microplastic pollution is becoming a continuously growing environmental concern, while bivalve mollusks are particularly vulnerable due to their sessile habits and feeding through water filtration processes. Microplastic incidence in soft tissues of the clam Amarilladesma mactroides was assessed along unconsolidated substrates distributed in extensive coastal regions of southern Brazil. Influence of urbanization levels, distance to rivers and local hydrodynamics on microplastic accumulation by the clam was tested. The average concentration of microplastics was high (3.09 ± 2.11 particles.g-1), considering 16 sampled sites. Particles were mainly composed by polyamide, polyethylene and polyethylene terephthalate, while were mainly smaller, fibrous and colorless. High urbanization and closer proximity to rivers insured higher contamination, which is a trend observed globally. No influence of coastal hydrodynamics was seen. Considering obtained findings, A. mactroides presents good potential to be used as a valuable tool to assess microplastic contamination in unconsolidated substrates of beach areas.

Trajectory, fate, and magnitude of continental microplastic loads to the inner shelf: A case study of the world's largest coastal shallow lagoon.

The Patos Lagoon estuary is a highly significant ecosystem where freshwater from a vast and densely populated area continuously flows into the Atlantic Ocean by coastal plumes, exporting not only freshwater but also sediment, nutrients, plastics, and other contaminants. In this work, numerical modeling tools together with field data were used to assess for the first time the capacity of the coastal plume to export microplastics (MPs) to the inner shelf under different hydrodynamic conditions. Two field surveys were conducted during plume events to quantify MP concentrations and validate the model approach. A bottom-up approach was employed to estimate the potential MP export from the estuary's domain to the Atlantic Ocean. MP concentration in surface plume waters ranged from 0.20 items m-3 to 1.37 items m-3, confirmed by FTIR as synthetic polymers in a 90 %, being Polypropylene (PP) and Polyethylene (PE) the most abundant in a 73 %. The accumulation pattern was observed on the plume's frontal system, consistent with simulation results. The estimated average MP potential export rate attained 9.0 million items day-1 during moderate plume events and 47.5 million items day-1 during high discharge plume events. Strong discharge events, coupled with intense northeast winds, facilitated rapid southwestward export of MPs. Conversely, moderate to weak discharge events retained MPs closer to the estuary's mouth, enabling either longer trajectories or earlier deposition. Significant MP accumulation hotspots were identified in the gyre between the jetties and Cassino beach, as well as in the saline front within the plume boundaries. These accumulation zones may function as reservoirs for MP particles, potentially posing threats to local ecosystems. Understanding these dynamics is crucial for ongoing monitoring efforts to assess potential harmful interactions over time.

Antifouling activity of isonitrosoacetanilides against microfouling and macrofouling.

Biofouling is responsible for structural and economic damage to man-made surfaces. Antifouling paints with biocides have been applied to structures to avoid organism adhesion; however, they have high toxicity and are not able to prevent all biofouling processes, necessitating the periodic mechanical removal of organisms and paint reapplication. Thus, there is an urgent demand for novel, effective, and environmentally friendly antifouling alternatives. As isonitrosoacetanilide is the precursor for many compounds with antibacterial activity, we believe that it could have antifouling activity against microfouling and, consequently, against macrofouling. The aim of this work was to investigate the antifouling potential of six isonitrosoacetanilide compounds and their toxicity. The compounds were employed at different concentrations (0.625-1.25-2.5-5-10 µg mL-1) in this study. The biofilm and planktonic bacteria inhibition and biofilm eradication potential were evaluated by crystal violet assay, while Amphibalus amphitrite barnacle settlement was evaluated by cyprid settlement assay. Toxicity evaluation (LC50 and EC50) was performed with A. amphitrite nauplii II and cyprid larvae. At least one of the tested concentrations of 4-Br-INA, 4-CH3-INA, and 2-Br-INA compounds showed nontoxic antifouling activity against microfouling (antibiofilm) and macrofouling (antisettlement). However, only 4-CH3-INA and 2-Br-INA also showed biofilm eradication potential. These compounds with antibiofilm activity and nontoxic effects could be combined with acrylic base paint resin or added directly into commercial paints in place of toxicant biocides to cover artificial structures as friendly antifouling agents.

Influence of UV exposure time and simulated marine environment on different microplastic degradation.

This study investigated the influence of environmental factors (UV radiation and salinity) in the degradative process of microplastics (MPs). MPs derived from polypropylene (PP), polystyrene (PS), and ethylene-vinyl acetate (EVA) were subjected to accelerated photodegradation while being submerged in distilled water or artificial seawater. Depending on the polymer, changes in surface properties, new functional chemical group formation and oxidative index, and thermal characteristics of samples were observed. After photodegradation experiments, EVA-MPs samples showed an increase in their thermal resistance, besides the changes in their surface. PP-MPs crystallinity index increased upon exposure to UV radiation. PS samples showed a higher carbonyl and hydroxyl index after 30 h of UV exposure. The methodology exploited applies to any location in the world and can be comparable once considering the total ultraviolet index (UVI). The saline medium increases the crystallinity index of PP and EVA-MPs samples and intensifies the formation of new carbonyl and hydroxyl bonds in EVA-MPs samples. The results showed that several environmental factors should be considered in interpreting MPs photodegradation.

Toxicity of antifouling biocides on planktonic and benthic neotropical species.

Organotin-based (OTs: TBT and TPT) antifouling paints have been banned worldwide, but recent inputs have been detected in tropical coastal areas. However, there is a lack of studies evaluating the toxicity of both legacy and their substitute antifouling booster biocides (e.g., Irgarol and diuron) on neotropical species. Therefore, the acute toxicity of four antifouling biocides (TBT, TPT, Irgarol, and diuron) was investigated using the marine planktonic organisms Acartia tonsa and Mysidopsis juniae, the estuarine tanaid Monokalliapseudes schubarti (water exposure), and the burrowing amphipod Tiburonella viscana (spiked sediment exposure). Results confirmed the high toxicity of the OTs, especially to planktonic species, being about two orders of magnitude higher than Irgarol and diuron. Toxic effects of antifouling compounds were observed at levels currently found in tropical coastal zones, representing a threat to planktonic and benthic invertebrates. Furthermore, deterministic PNECmarine sediment values suggest that environmental hazards in tropical regions may be higher due to the higher sensitivity of tropical organisms. Since regulations on antifouling biocides are still restricted to a few countries, more ecotoxicological studies are needed to derivate environmental quality standards based on realistic scenarios. The present study brings essential contributions regarding the ecological risks of these substances in tropical and subtropical zones.

Comparative toxicity of antifouling compounds on the development of sea urchin.

In the present study, embryotoxicity experiments using the sea urchin Lytechinus variegatus were carried out to better clarify the ecotoxicological effects of tributyltin (TBT) and triphenyltin (TPT) (the recently banned antifouling agents), and Irgarol and Diuron (two of the new commonly used booster biocides). Organisms were individually examined to evaluate the intensity and type of effects on embryo-larval development, this procedure has not been commonly used, however it showed to be a potentially suitable approach for toxicity assessment. NOEC and LOEC were similar for compounds of same chemical class, and IC10 values were very close and showed overlapping of confidence intervals between TBT and TPT, and between Diuron and Irgarol. In addition, IC10 were similar to NOEC values. Regardless of this, the observed effects were different. Embryo development was interrupted at the gastrula and blastula stages at 1.25 and 2.5 µg l(-1) of TBT, respectively, whereas pluteus stage was reached with the corresponding concentrations of TPT. Furthermore, embryos reached the prism and morula stages at 5 µg l(-1) of TPT and TBT, respectively. The effects induced by Irgarol were also more pronounced than those caused by Diuron. Pluteus stage was always reached at any tested Diuron concentration, while embryogenesis was interrupted at blastula/gastrula stages at the highest concentrations of Irgarol. Therefore, this study proposes a complementary approach for interpreting embryo-larval responses that may be employed together with the traditional way of analysis. Consequently, this application leads to a more powerful ecotoxicological assessment tool focused on embryotoxicity.

Bacteria-invertebrate interactions as an asset in developing new antifouling coatings for man-made aquatic surfaces.

Economic losses can result from biofouling establishment on man-made structures. Macrofouling causes damage to artificial substrates, which justifies the need for its control. However, the antifouling coatings employed nowadays are typically not safe for the environment. Microfouling can affect macrofouling colonization, and thus represents a potential target for alternative antifouling control. From both ecological and economical points of view, information on the ecology and interactions between micro- and macrofouling are crucial to develop successful and safe control strategies, which will prevent biofouling development on man-made structures while preserving water quality and the safety of non-target organisms. This study presents a metabarcoding analysis of biofilm-associated marine bacteria (16S-rRNA-gene) and fungi (ITS-region), with the aim to understand invertebrate settlement over time on hard substrates exposed to natural condition (Control) and two treatments (Antimicrobials and Antifouling Painted). Biofouling composition changed with exposure time (up to 12 days) and showed differences among Control and Antimicrobials and Painted treatments. Antimicrobial treatment influenced more the biofouling composition than traditional antifouling paint (Cu2O-based). Both treatments caused microbial resistance. Macrofouling establishment was strongly influenced by Gram-negative heterotrophic bacteria (mostly Proteobacteria and Bacteroidetes). Nevertheless, each macrofouling taxon settled in response to a specific biofilm bacterial composition, although other factors can also affect the biofouling community as the condition of the substrate. We suggest that proper friendly antifouling technologies should be focused on inhibiting bacterial biofilm adhesion.

Surface coatings select their micro and macrofouling communities differently on steel.

Previous studies have shown the effect of surface coatings on biofouling; however, they did not take into account the interaction of the micro and macrofouling communities, the effect of substrate orientation and the zooplankton-zoobenthic coupling together. Therefore, the aim of this study was to evaluate the effect of Zn- and Cu2O-based coatings on micro and macrofouling on steel surfaces, while also observing the role of substrate orientation and zooplankton supply. An experiment was carried out in the Patos Lagoon Estuary in southern Brazil for three months between spring and summer, where ASTM-36 steel plates represented different coatings (Zn- and/or Cu2O-based) and orientations (vertical and horizontal). To assess the zooplankton supply, sampling was carried out weekly using a 200 µm plankton net. Zn-based coating positively affected microfouling density compared to uncoated surfaces. The same pattern was observed with macrofouling, associated with vagile fauna preference, which represented 70% of the settled macrofoulers. Cu2O-based antifouling painted surfaces showed the highest microfouling density inhibition, while Zn + Cu2O-based coating did not affect the bacteria adhesion but showed lower density compared to Zn-based coating alone. The coatings combination showed the highest invertebrate inhibition. In this way, the macrofouling community was more sensitive than microfouling was to the antifouling coatings tested. The substrate orientation only affected macrofouling, horizontal surfaces being more attractive than vertical. Meroplankton, tychoplankton and holoplankton were recorded on the surfaces, although their representation in plankton was not proportional to the recruits recorded on the substrates. This was probably due to fast dispersion, the interactions of other factors and/or ecological succession stage. Surface coating, substrate orientation, and zooplankton supply interacted with the biofouling process on steel in different ways depending on the organism evaluated. Therefore, copper oxide- and zinc-based coatings were not suitable as coatings to avoid the total biofouling establishment.

Natural and non-toxic products from Fabaceae Brazilian plants as a replacement for traditional antifouling biocides: an inhibition potential against initial biofouling.

In this study, we screened for the antifouling activity of 15 species plant extracts from Brazilian the Brazilian Caatinga Fabaceae against the initial colonization of natural marine bacterial biofilm. We also investigated the potential toxicity of extracts against planktonic and benthic non-target organisms. Aqueous extracts of plants collected in the Caatinga biome (PE, Brazil) were prepared and tested at different concentration levels (0, 0.5, 1, 2, 4, and 8 mg mL-1). Natural marine bacterial consortium was inoculated in multi-well plates and incubated with the different treatments for 48 h. The biofilm and planktonic bacterial density and biomass inhibition were evaluated along with biofilm biomass eradication. The extracts that showed the highest bacterial biofilm inhibition were evaluated for toxicity against microalgae and crustaceans. The biofilm and planktonic bacterial inhibition potential were evaluated through flow cytometry and spectrophotometry. The selected treatments were evaluated for their toxicity using the microalgae Chaetoceros calcitrans, the copepod Nitokra sp., and the brine shrimp Artemia salina as bioindicators. Our work demonstrates the biotechnological potential of Fabaceae plant compounds as a safe antifouling alternative. Anadenanthera colubrina var. cebil fruits and Apuleia leiocarpa leaf extracts showed antibiofilm activity (≥ 80%), while Myroxylon peruiferum and Dioclea grandiflora leaf extracts showed antibiotic activity. These extracts were safe to planktonic and benthic non-target organisms. The results of this study point to potential substitutes to highly toxic antifouling paints and shed light on the prospect of a yet to be explored biome for more sustainable alternatives in biofouling research.

Antifouling paint particles: Sources, occurrence, composition and dynamics.

Sources, occurrence, composition and dynamics of antifouling paint particles (APPs) were assessed in Patos Lagoon estuary (PLE), Southern Brazil. Ten areas including boatyards, a marina and artisanal fishing harbors were identified in the estuarine system as potential sources of APPs. The APPs generated in these areas were highly heterogeneous considering the size, shape and composition. Based on an estimate of antifouling paint usage and amount of boats in each studied area, artisanal fishing harbors could be the main source of particles to PLE. However, relatively high amounts of APPs, which ranged from 130 to 40,300 µg g-1, were detected in sediments collected in front of boatyards and a marina. The uneven distribution of APPs levels among the sediment samples were probably due to the presence of diffuse sources (fishing harbors) associated to "hotspots" (boatyards and marina) along the study area. Additionally, data of settling experiment indicate that size, shape and density of APPs, combined to local hydrodynamics, appears to contribute to the mobility of these residues within the estuary. In the main channel of PLE, smaller particles tend to be transported to adjacent coastal zone while particles tend to be deposited in the sediment surface of sheltered areas. Since different trace metals, and booster biocides were detected in APPs that were not correctly disposed, these particles can be considered as an important source of contamination to aquatic environments. The present data suggest that APPs represent an environmental problem for aquatic systems in Brazil, since the country lacks legislation in addition to inefficient control mechanisms. An improvement in boat maintenance processes are urgently needed to avoid this continuous release of APPs into the aquatic systems.

Physiological effects of copper in the euryhaline copepod Acartia tonsa: waterborne versus waterborne plus dietborne exposure.

The physiological effects of waterborne and waterborne plus dietborne copper exposure were determined in the euryhaline copepod Acartia tonsa at different salinities (5, 15 and 30ppt). Copepods were exposed (48h) to a reported 48-h LC50 for copper (CuCl(2)), which had been previously determined under the same experimental conditions. Whole body copper accumulation, ion concentrations (Na(+), Cl(-), Mg(2+)), and Na(+), K(+)-ATPase activity were the endpoints measured in all experimental groups. Feeding rate was also measured in fed experimental groups. In copper-exposed copepods, whole body copper accumulation was dependent on salinity, decreasing as salinity increased. However, it was similar in copepods exposed to waterborne and waterborne plus dietborne copper, irrespective the salinity tested. Waterborne copper exposure induced a disturbance of the whole body Na(+) concentration in all salinities tested. This effect was characterized by an increased whole body Na(+) concentration in seawater (salinity 30ppt) and a decreased whole body Na(+) concentration at lower salinities (5 and 15ppt). The ionoregulatory imbalance in low salinity (5ppt) was associated with an inhibition of the whole body Na(+), K(+)-ATPase activity, as observed in freshwater fish and crustaceans. When copepods were exposed to waterborne plus dietborne copper, the physiological effects described were only observed at a low salinity (5ppt) and were associated with a marked inhibition of the feeding rate. Taken altogether, the data suggest that the physiological effects induced by waterborne copper exposure in A. tonsa acclimated to higher salinities (15 and 30ppt) are due to a combined effect of food restriction and copper exposure. Differential physiological responses to waterborne and waterborne plus dietborne copper cannot be ascribed to differences in whole body copper burden.

Are antifouling paint particles a continuous source of toxic chemicals to the marine environment?

Antifouling paint particles (APPs) are generated during periodical maintenance of boat hulls. Chemical composition and toxicity (either chronic or acute) of APPs found in the sediment was evaluated using the epibenthic copepod Nitokra sp. The APPs analyzed showed the presence of high levels of metals such as Cu (234,247±268µgg-1), Zn (112,404±845µgg-1) and the booster biocide DCOIT (0.13µgg-1). Even at low concentrations (as from 5mgg-1 of APPs by mass of sediment) a significantly decrease in the fecundity was observed in laboratory tests. When the sediment was disturbed in elutriate test, a LC50 of 0.14% for APPs was found. This study was the first assessment of toxicity associated with the presence of APPs in sediment to benthic organisms, and it calls attention to the need of improving regulations in boatyards and marina areas.

Acute waterborne copper toxicity to the euryhaline copepod Acartia tonsa at different salinities: influence of natural freshwater and marine dissolved organic matter.

The influence of natural dissolved organic matter (DOM) on acute waterborne Cu toxicity was evaluated in the euryhaline copepod Acartia tonsa at 3 different water salinities. Three sources of freshwater DOM (extracted by reverse osmosis) and 2 sources of marine DOM (extracted using a solid-phase technique) were used. Artificial salt water was used to prepare the experimental media. Different combinations of Cu concentrations and DOM sources and concentrations were tested at salinities of 5, 15, and 30 ppt. Toxicity data (48-h median lethal concentration [LC50] values) were calculated based on dissolved Cu concentrations. In a broad view, data showed that increasing salinity was protective against the acute waterborne Cu toxicity. In general, Cu toxicity was also lower in the presence than in the absence of DOM. Toxicity (48-h LC50) values from all treatments at the same salinity showed a positive linear relationship with the dissolved organic carbon (DOC). Thus, the protective effect of DOM against the acute Cu toxicity seems to be dependent mainly on the DOM concentration. However, it seems also to be dependent to some extent on the source of DOM used. In summary, findings reported in the present study clearly indicate that both salinity and DOM (source and concentration) should be taken into account in the development of an estuarine version of the biotic ligand model.

Biomarkers of waterborne copper exposure in the guppy Poecilia vivipara acclimated to salt water.

The responses of a large suite of biochemical and genetic parameters were evaluated in tissues (liver, gills, muscle and erythrocytes) of the estuarine guppy Poecilia vivipara exposed to waterborne copper in salt water (salinity 24 ppt). Activities of antioxidant enzymes (superoxide dismutase, catalase, glutathione reductase, and glutathione S-transferase), metallothionein-like protein concentration, reactive oxygen species (ROS) content, antioxidant capacity against peroxyl radicals (ACAP), and lipid peroxidation (LPO) were evaluated in liver, gills, and muscle. Comet assay score and nuclear abnormalities and micronucleated cell frequency were analyzed in peripheral erythrocytes. The responses of these parameters were evaluated in fish exposed (96 h) to environmentally relevant copper concentrations (5, 9 and 20 µg L⁻¹). In control and copper-exposed fish, no mortality was observed over the experimental period. Almost all biochemical and genetic parameters proved to be affected by waterborne copper exposure. However, the response of catalase activity in liver, ROS, ACAP and LPO in muscle, gills and liver, and DNA damages in erythrocytes clearly showed to be dependent on copper concentration in salt water. Therefore, the use of these parameters could be of relevance in the scope of biomonitoring programs in salt water environments contaminated with copper.

Acute copper toxicity in the euryhaline copepod Acartia tonsa: implications for the development of an estuarine and marine biotic ligand model.

Copepods (Acartia tonsa) were exposed (48 h) to waterborne, diet-borne (non-Cu-equilibrated and Cu-equilibrated food), and waterborne plus diet-borne Cu in either the absence or the presence of food (diatom Thalassiosira weissflogii). Toxicity tests were run in different salinities (5, 15, and 30 ppt) together with measurements of physicochemical parameters and total and dissolved Cu concentrations in the experimental media. Results show that most of the toxic Cu fraction was in the dissolved phase. In general, Cu toxicity was higher in low (5 ppt) than in high salinity (30 ppt), regardless of the pathway of Cu exposure tested. In the absence of food, data clearly indicate that differences in waterborne Cu toxicity can be explained by changes in water chemistry. However, addition of food (either non-Cu-equilibrated or Cu-equilibrated) to the experimental media protected against acute Cu toxicity in salinities 5 and 15 ppt, suggesting that A. tonsa requires extra energy to cope with the stressful condition imposed by Cu exposure associated with the ionoregulatory requirements in low salinities. For diet-borne exposure, a very high Cu concentration was necessary to precontaminate the diatoms to a level resulting in copepod mortality. Therefore, availability of food exerted a more important positive impact in protecting against acute Cu toxicity than its potential negative impact via contamination resulting in toxicity. Findings indicate the need for incorporation of both salinity and food in a future biotic ligand model (BLM) version for Cu in estuarine and marine waters. In this context, the euryhaline copepod A. tonsa would be a suitable model species with which to perform experiments to validate and calibrate any future saltwater BLM.

Long-term ammonia toxicity to the pink-shrimp Farfantepenaeus paulensis.

Juvenile pink-shrimp Farfantepenaeus paulensis were exposed (75 days) to NH(3) (0.016-0.287 mg L(-1)) under static condition with water renewal every 24h. Experiments were performed at 20 degrees C, at a water salinity of 15 ppt, and at pH 7.8. Endpoints analyzed were survival, growth and predation rates. After 75 days of exposure, survival was >or=90% in all concentrations tested. However, growth (carapace length and wet body mass) was reduced after exposure to NH(3) concentrations as low as 0.033 mg L(-1), while the relative growth (dry body mass and ash content) was reduced after exposure to the highest NH(3) concentration (0.287 mg L(-1)). Predatory activity was inhibited after exposure to 0.144 or 0.287 mg L(-1) NH(3). Post-larvae exposed (75 days) to 0.301 mg L(-1) NH(3) under the same experimental conditions also showed a reduced growth (wet body mass) and relative growth (dry body mass). In addition, they showed decreased body lipids content and increased body glycogen and glucose contents. However, no changes in body protein, chitin and uric acid contents were observed. Also, NH(3) did not affect post-larvae feeding response. Altogether, findings suggest that F. paulensis reduces its food intake to limit the internal accumulation of nitrogenous waste products when exposed for long time to high levels of ambient ammonia. As a consequence, shrimp show a marked change in energy metabolism, characterized by a decreased content of body lipids paralleled by an increased content of body carbohydrates, resulting in a significant reduction in growth.