Nitocra Spinipes Research Articles

A short life‐cycle test with the epibenthic copepod Nitocra spinipes for sediment toxicity assessment

A new short life-cycle test methodology is presented to evaluate sublethal effects of contaminated sediments to the harpacticoid copepod species Nitocra spinipes. The method combines a 4-d survival-gravidity test with a 7-d development test. For water-only Cu exposures, the sensitivity of the development test endpoints were compared with tests using nonexposed gravid females to initiate the 7-d development test phase, and also with a multiple generation test comprising three successive phases: 9-d development; 21-d survival-gravidity; second-generation 9-d development. The results indicated that the development endpoints were the most sensitive, with median effective concentration (EC50) values of 95 µg Cu/L for nauplii/gravid female and 101 µg Cu/L copepodites/gravid female endpoints, followed by the gravidity (144 µg Cu/L) and survival (347 µg Cu/L). The sensitivity of the short life-cycle test endpoints was similar to the multiple-generation test endpoints, and the shorter test had less variability in controls. The multiple-generation test showed a large amount of stimulation of reproduction and development at Cu concentrations of 50 to 100 µg/L. The suitability of the short life-cycle test for assessing sediment toxicity was demonstrated using Cu-spiked and naturally contaminated whole sediments. Although the small nauplii were more difficult to isolate from sediments, the small amounts of sediments used for the tests and the large effects of the contaminated sediments on nauplii and copepodite numbers resulted in significant differences to controls. For sediment exposures, the sensitivity of the endpoints was in the order development > gravidity > survival. The short life-cycle test was demonstrated to detect, within 11 d of exposure, similar levels of effects on reproduction and development to those detected using a 39-d multiple-generation exposure.

An Assessment of Three Harpacticoid Copepod Species for Use in Ecotoxicological Testing

The relatively short life cycles of harpacticoid copepods makes them appropriate animals for use in tests that rapidly assess the acute, sublethal, or chronic effects of sediment contaminants. In this study, four harpacticoid copepod species (Nitocra spinipes, Tisbe tenuimana, Robertgurneya hopkinsi, and Halectinosoma sp.) were isolated from clean marine sediments, and procedures for laboratory culturing were developed. Halectinosoma sp. was abandoned due to handling difficulties. For the remaining species, the influence of food type and quantity on life-cycle progression was assessed. A mixed diet, comprising two species of algae (Tetraselmis sp. and Isochrysis sp.) and fish food (Sera Micron) was found to maintain healthy cultures and was fed during laboratory tests. Water-only exposure to dissolved copper (Cu) showed that the times (range) required to cause 50% lethality (LT(50)) were 24 (22-27) h at 50 μg Cu/l for T. tenuimana; 114 (100-131) and 36 (32-40) h for 200 and 400 μg Cu/l, respectively, for N. spinipes; and 119 (71-201) and 25 (18-33) h for 200 and 400 μg Cu/l, respectively, for R. hopkinsi. 96-h LC(50) (concentration causing 50% lethality) were also determined for adult N. spinipes exposed to cadmium, copper, zinc, ammonia, and phenol. A ranking system was generated based on the ease handling and culturing, rate of maturity, food selectivity and sensitivity to Cu. From this ranking, N. spinipes was determined to be the most suitable species for use in developing sediment-toxicity tests. The measurement of total reproductive output of N. spinipes during 10-day exposure to whole sediment was found to provide a useful end point for assessing the effects of sediment contamination.

Chemical risks and consumer products: The toxicity of shoe soles

The European chemicals legislation, REACH, aims to ensure a high level of protection of human health and the environment. However, chemicals included in consumer products are covered only to a very limited extent even though they constitute the main source of chemical emissions. Shoes are large volume products and the overall aim of the present study was to study the ecotoxicological effects of three types of shoe soles and relate these effects to chemical emissions to the aquatic environment. The shoe soles were abraded and leached in water for 29 days and the alga Ceramium tenuicorne and the crustacean Nitocra spinipes were exposed to different concentrations of the leachate. Chemical analyses were performed to determine the chemical contents of the leachate. The main conclusions are that the shoe soles contain substances that are toxic to both test organisms, and that the toxicity is mainly explained by the presence of zinc. The estimated concentration of zinc from shoe soles in storm water runoff is low, but it still contributes to the overall load of chemicals and metals in the environment. The outlined test procedures may, in our view, provide a useful screening tool for assessing the risk that chemicals in consumer articles pose to the environment.

A single‐step staining method to evaluate egg viability in zooplankton

A simplified method for viability analysis of zooplankton eggs by staining of nonviable eggs with a fluorescent nucleic acid stain TO‐PRO‐1 iodide is proposed here as a further development of fluorescence‐based egg viability assays. This is one‐step analysis with no intermediate steps for chorion removal. The method was calibrated using predetermined mixtures of viable and nonviable eggs (rotifers and copepods), and validated using hatching experiments (copepods) and egg development assay (cladocerans) as reference measurements. In these tests, eggs of several zooplankton species, Brachionus plicatilis (Rotatoria), Daphnia magna (Cladocera), Nitocra spinipes (Harpacticoida), Acartia tonsa (Calanoida), were used. Moreover, staining efficiency was not affected by storage of samples for up to 1 month in −80°C, making the assay suitable for egg viability assessment in field and laboratory studies. To illustrate usefulness of the method, it was applied to evaluate how absence of re‐mating affects production of viable eggs in females of A. bifilosa (Calanoida). In females separated from males, proportion of sterile eggs increased in 3 d after the separation and no viable eggs were produced after 5 d. The effects of mating frequency on egg viability are important to understand when designing egg production experiments and interpreting field data on egg viability in populations with skewed sex ratios.

Comparison of toxicity and release rates of Cu and Zn from anti-fouling paints leached in natural and artificial brackish seawater

Biocide-containing anti-fouling paints are regulated and approved according to the added active ingredients, such as Cu. Biocide-free paints are considered to be less environmentally damaging and do not need an approval. Zn, a common ingredient in paints with the potential of causing adverse effects has received only minor attention. Laboratory experiments were conducted in artificial brackish seawater (ASW) and natural brackish seawater (NSW) to quantify release rates of Cu and Zn from biocide-containing and biocide-free labeled eroding anti-fouling paints used on commercial vessels as well as leisure boats. In addition, organisms from three trophic levels, the crustacean Nitocra spinipes, the macroalga Ceramium tenuicorne and the bacteria Vibrio fischeri, were exposed to Cu and Zn to determine the toxicity of these metals. The release rate of Cu in NSW was higher from the paints for professional use (3.2–3.6 µg cm − 2 d − 1 ) than from the biocide leaching leisure boat paint (1.1 µg cm − 2 d − 1 ). Biocide-free paints did leach considerably more Zn (4.4–8.2 µg cm − 2 d − 1 ) than biocide-containing leisure boat paint (3.0 µg cm − 2 d − 1 ) and ship paints (0.7–2.0 µg cm − 2 d − 1 ). In ASW the release rates of both metals were notably higher than in NSW for most tested paints. The macroalga was the most sensitive species to both Cu (EC 50 = 6.4 µg l − 1 ) and Zn (EC 50 = 25 µg l − 1 ) compared to the crustacean (Cu, LC 50 = 2000 µg l − 1 Zn, LC 50 = 890 µg l − 1 ), and the bacteria (Cu, EC 50 = 800 µg l − 1 and Zn, EC 50 = 2000 µg l − 1 ). The results suggest that the amounts of Zn and Cu leached from anti-fouling paints may attain toxic concentrations in areas with high boat density. To fully account for potential ecological risk associated with anti-fouling paints, Zn as well as active ingredients should be considered in the regulatory process.

Comparison of six sewage effluents treated with different treatment technologies—Population level responses in the harpacticoid copepod Nitocra spinipes

Since conventional treatment technologies may fail in removing many micro-pollutants, there is currently a focus on the potential of additional treatment technologies for improved sewage treatment. The aim of the present study was to evaluate six different effluents from Henriksdal Sewage Treatment Plant in Stockholm, Sweden. The effluents were; conventionally treated effluent (chemical phosphorous removal in combination with an activated sludge process, including biological nitrogen removal and a sand filter), with additional treatments individually added to the conventional treatment; active carbon filtration, ozonation at 5 mg l −1, ozonation at 15 mg l −1, ozonation at 5 mg l −1 + moving bed biofilm reactor and irradiation with ultraviolet radiation + hydrogen peroxide. The evaluation was done by characterizing and comparing the effluents using a Lefkovitch matrix model based on a life cycle test with the harpacticoid copepod Nitocra spinipes, combined with analysis of juvenile development and survival over time. The conventionally treated effluent resulted in the most negative effects, leading to the conclusion that all additional treatments in the present study created effluents with less negative impacts on the copepod populations. The ozone treatments with the low dose treatment in particular, resulted in the overall least negative effects. Moving bed biofilm reactor combined with ozone did not improve the quality of the effluent in the sense that slightly more negative effects on the population abundance were seen for this treatment technology compared to ozonation alone. The active carbon treatment had more negative effects than the ozone treatments, most of which could possibly be explained by removal of essential metal ions. The effluent which was treated with ultraviolet radiation + hydrogen peroxide resulted in few developmental and survival effects over time, but still showed negative effects on the population level. Matrix population modeling proved a useful tool for biologically characterizing and comparing the effluents. Basing the assessment either on the individual level data (development and survival over time or total reproductive output) or the population level data (lambda values and projected population abundances) would not have resulted in the same conclusions as combining both analyses. The juvenile development and survival over time allowed for closer monitoring of the important molting process, whereas the population modeling provided an integrated measure of potential effects at the population level. If the dilution of the effluent in the recipient is considered, the biological effects recorded in the present study were not of substantial significance for the copepod populations, regardless of treatment technology.

Toxicity of anti-fouling paints for use on ships and leisure boats to non-target organisms representing three trophic levels

Leachates of anti-fouling paints for use on ships and leisure boats are examined for their ecotoxicological potential. Paint leachates were produced in both 7‰ artificial (ASW) and natural seawater (NSW) and tested on three organisms, the bacterium Vibrio fischeri, the macroalga Ceramium tenuicorne, and the crustacean Nitocra spinipes. Generally, leaching in ASW produced a more toxic leachate and was up to 12 times more toxic to the organisms than was the corresponding NSW leachate. The toxicity could be explained by elevated concentrations of Cu and Zn in the ASW leachates. Of the NSW leachates, those from the ship paints were more toxic than those from leisure boat paints. The most toxic paint was the biocide-free leisure boat paint Micron Eco. This implies that substances other than added active agents (biocides) were responsible for the observed toxicity, which would not have been discovered without the use of biological tests.

Biological and chemical characterization of harbour sediments from the Stockholm area

The main objective of the current study was to assess the impact of pleasure boat activities on harbour sediment quality in the Stockholm area. Sediment contamination is a growing ecological issue, and there is consequently a need to use sediment bioassays in combination with chemical analysis to determine the impact on the ecosystem. To generate sediment toxicity data relevant for the Baltic Sea, a secondary objective was to further develop and evaluate two well-established bioassays for saltwater, with the macroalga Ceramium tenuicorne and the crustacean Nitocra spinipes, to be useful also for toxicity testing of whole sediment. A major concern has been to minimize any manipulation of the sediments. A third objective was to assess whether a simple leaching procedure could be used to simulate sediment toxicity by comparing results from whole sediment and leachate tests. Surface sediments (0–2 cm) from five different types of pleasure boat harbours were collected. Chemical measurements of boat related compounds, i.e. tin organic substances (tributyltin (TBT), dibutyl tin, and monobutyl tin), polyaromatic hydrocarbons (PAHs), copper, zinc, lead, tin and irgarol were conducted. The sediments were tested for toxic effects using the established Microtox® test as well as the developed sediment tests with C. tenuicorne and N. spinipes. The endpoints are growth inhibition for the algal test and for the crustacean test mortality of larvae and rate of development expressed as the ratio between nauplia and copepodites. Two different procedures have been compared with both organisms, i.e. exposure to whole sediment and to leachate. The duration of both tests is around 1 week. All harbour locations were more or less heavily contaminated with remnants from use of anti-fouling paints. The sediment in a smaller marina (ca. 250 boats) contained the highest levels of TBT (max 1,400 µg/kg dry weight (dw)), whereas the centre of Stockholm City had the highest concentrations of all measured metals (max values Cu 252, Pb 830, Sn 25 and Zn 600 µg/kg dw) as well as high concentrations of total PAH (18 mg/kg dw). All three organisms were well suited to test the toxicity of contaminated sediments and were able to discriminate between more or less polluted sediments. The sediments in the smaller marina were most toxic along with sediments adjacent to slipways and sediments from the centre of Stockholm. No significant difference was found between the two different procedures for the algal tests. The whole sediment test was significantly more toxic to N. spinipes than the test using leachate. Our results show that in spite of prohibition for many years to use tin organic substances and copper, boat activities still contribute with high concentrations of these toxic substances from anti-fouling paints in the surface sediment and that these have effects on organisms normally living in this environment. The present study has also demonstrated an expansion of two well-established toxicity tests for the water phase to be practical also for sediment toxicity testing. This will further increase the usefulness of these test organisms and methods for hazard and risk assessment in a wide range of environments.

Are individual NOEC levels safe for mixtures? A study on mixture toxicity of brominated flame–retardants in the copepod Nitocra spinipes

In aquatic ecosystems organisms are exposed to mixtures of pollutants. Still, risk assessment focuses almost exclusively on effect characterization of individual substances. The main objective of the current study was therefore to study mixture toxicity of a common group of industrial substances, i.e., brominated flame–retardants (BFRs), in the harpacticoid copepod Nitocra spinipes. Initially, 10 BFRs with high hydrophobicity but otherwise varying chemical characteristics were selected based on multivariate chemical characterization and tested individually for effects on mortality and development using a partial life cycle test (six days) where silica gel is used as a carrier of the hydrophobic substances. Based on these findings, six of the 10 BFRs were mixed in a series of NOEC proportions (which were set to 0.008, 0.04, 0.2, 1, and five times the NOEC concentrations for each individual BFR), loaded on silica gel and tested in a full life cycle test (26 days). Significantly increased mortality was observed in N. spinipes after six and 26 days exposure at a NOEC proportion that equals the NOEC LDR value (×1) for each BFR in the mixture ( p = 0.0015 and p = 0.0105, respectively). At the NOEC × 5 proportion all animals were dead. None of the other NOEC proportions caused significant negative responses related to development and reproduction. This shows that low concentrations of individual substances can cause toxicity if exposed in mixtures, which highlights the need to consider mixture toxicity to a greater extent in regulatory work.

Food quality effects on copepod growth and development: Implications for bioassays in ecotoxicological testing

We evaluated effects of six algal species in 25 combinations on growth and reproduction of the harpacticoid copepod Nitocra spinipes. In the first lifecycle test, Rhodomonas salina, Phaeodactylum tricornutum, and Dunaliella tertiolecta were used. The results showed that R. salina was the best food, whereas P. tricornutum (0% development success) and D. tertiolecta (41.7% malformations) were poor food items. In the second lifecycle test, a mixture of R. salina, Tetraselmis suecica, and Thalassiosira weisflogii (selected from screening tests) was tested together with a mono-diet of R. salina. Also in this test, copepods fed R. salina performed better (i.e. had higher survival and reproductive success) compared with the other treatment. We conclude that R. salina is appropriate to use as food in toxicity testing with N. spinipes, whereas some of the algae commonly used as feed in ecotoxicological tests with other copepods had detrimental effects on the development, reproduction, and survival of N. spinipes.

Integrating individual ecdysteroid content and growth-related stressor endpoints to assess toxicity in a benthic harpacticoid copepod

Anthropogenic chemicals released into the environment may have so-called endocrine disruptive effects. For instance, innumerous observations on subtle alterations of fish reproductive systems have been published in the scientific literature during the last decades. At the same time, the evidence is scarce regarding similar effects in crustaceans, which is probably related to the limited understanding of basic crustacean endocrine systems and pathways, rather than absence of endocrine disruption within the crustacean subphylum. This knowledge gap is particularly evident in micro-crustacean species, which are frequently used in environmental risk assessment of chemicals, and adequate tools for identification of potential endocrine disrupters are missing in current chemicals regulation. The main objective of the current study was therefore to utilize an enzyme immunoassay to establish a stable protocol for analysis of individual ecdysteroid levels in the benthic harpacticoid copepod Nitocra spinipes, a species which has been used in ecotoxicological investigations for more than 30 years. Further, to assess the usefulness of the individual ecdysteroid level as a stressor endpoint, it was integrated with a growth-related stressor endpoint battery, i.e. individual RNA content, mean development times, and growth rate, by exposing individual N. spinipes to the insecticide and known ecdysteroid antagonist lindane at 25–400 μg L −1. The results showed that the ecdysteroid levels were significantly different from the control (71 pg individual −1) in the 100 μg L −1 treatment (124 pg individual −1). Although the ecdysteroid levels were not significantly different from the control in the 25–50 μg L −1 treatments (83–93 pg individual −1), these results still show a clear concentration-related trend. In the 200 μg L −1 treatment, the ecdysteroid content was the highest (165 pg individual −1), however not significantly different from the control due to high variation. The 400 μg L −1 treatment resulted in lowered ecdysteroid levels (107 pg individual −1), indicating a profound lindane-induced stress, which was confirmed by high mortality in the same treatment (79%). For all other endpoints there were clear concentration-related effects of lindane, with development time and growth rate as the most sensitive endpoints. In conclusion, this study presents for the first time a tool for identification of endocrine alterations in N. spinipes. By using the established enzyme immunoassay protocol, we obtained individual ecdysteroid levels that integrated well with the growth-related stressor endpoints previously used on this species.

Silica gel as a particulate carrier of poorly water-soluble substances in aquatic toxicity testing

Aquatic toxicity tests were originally developed for water-soluble substances. However, many substances are hydrophobic and thus poorly water-soluble, resulting in at least two major implications. Firstly, toxicity may not be reached within the range of water solubility of the tested compound(s), which may result in the formation of solids or droplets of the tested substance and consequently an uneven exposure. Secondly, because of multi-phase distribution of the tested substance it may be complicated to keep exposure concentrations constant. To overcome such problems, we have introduced silica gel as a particulate carrier in a toxicity test with the benthic copepod Nitocra spinipes. The main objective of the current study was to evaluate whether a controlled exposure could be achieved with the help of silica gel for testing single poorly water-soluble substances. A secondary objective was to evaluate whether an equilibrium mass balance model could predict internal concentrations that were consistent with the toxicity data and measured internal concentrations of two model hydrophobic substances, i.e., the polybrominated diphenyl ethers BDE-47 and BDE-99. Larval N. spinipes were exposed for 6 days to BDE-47 and BDE-99, respectively, in the silica gel test system and, for comparative reasons, in a similar and more traditional semi-static water test system. Via single initial amounts of the model substances administered on the silica gel, effects on both larval development and mortality resulted in higher and more concentration-related toxicity than in the water test system. We conclude that the silica gel test system enables a more controlled exposure of poorly water-soluble substances than the traditional water test system since the concentration–response relationship becomes distinct and there is no carrier solvent present during testing. Also, the single amount of added substance given in the silica gel test system limits the artefacts (e.g., increased chemical load in test system) that a semi-static renewal may introduce when testing substances that partition to non-water phases. However, measured and modelled internal concentrations did not match toxicity, which may indicate that chemical equilibrium was not reached during the test. Further experiments are thus needed to explain the processes behind the observed positive effects of silica gel and a kinetic model would likely also be more appropriate to describe the concentrations and distributions in the two test systems.

Effects of TNT leakage from dumped ammunition on fish and invertebrates in static brackish water systems

The objective of the present study was to study the release and effect of TNT from dumped ammunition. Cleaved artillery shells were placed in static brackish water systems for 5 months, and another 12 months with 5 cm sediment burial. The toxicity was determined in bioassays with crustaceans ( Nitocra spinipes and Hyalella azteca) and/or European flounder ( Platichtys flesus). The water phase was analysed for TNT using colorimetric method and GC-MS. This study showed a rapid release of TNT to acutely toxic concentrations when the cleaved ammuniton was not covered with sediment under static conditions, but that the release was effectively inhibited by sediment burial of the artillery shells. Hence, at least in a short-term perspective, acute adverse effects of sediment-buried ammunition on aquatic organisms should be greatly reduced.

Towards an internationally harmonized test method for reproductive and developmental effects of endocrine disrupters in marine copepods

New and updated methods to detect and characterize endocrine disrupting chemicals (EDCs) are urgently needed for the purpose of environmental risk assessment since these substances are often not detected using existing chronic toxicity tests. Numerous reports on the effects of EDCs on crustacean development and reproduction have been published and the development of life-cycle tests with crustaceans has been prioritized within the OECD work program for endocrine disrupter testing and assessment. As a result, Sweden, and Denmark initiated a proposal for development of a full life-cycle test with marine copepods (Acartia tonsa, Nitocra spinipes, Tisbe battagliai, and Amphiascus tenuiremis). The present paper gives an overview on the endocrine system of crustaceans with special emphasis on development and reproduction, which are targets for endocrine disruption, and reviews available methods for detecting effects on development and reproduction in calanoid and harpacticoid copepods. A draft OECD guideline Copepod Development and Reproduction Test has been developed, and a pre-validation of this draft guideline was completed in 2005. An updated draft guideline, taking into account the results of the pre-validation, is now under validation in an international ring-test, which is running till the end of 2006.

TNT leakage through sediment to water and toxicity to Nitocra spinipes

The fate and effects of 2,4,6-trinitrotoluene (TNT) at marine ammunition dumping sites are essentially unknown. The objective of this study was to examine the release from solid TNT to seawater when covered by sediment of two different types (sandy and fine-grained) and thickness (0, 1, 2, and 4 cm), under different temperatures (5, 10, and 20 °C), and light conditions (ambient daylight and darkness) in the laboratory. The water column was analysed for TNT and some of its common transformation products, and toxicity to the copepod Nitocra spinipes after 1, 2, 4, 8, 19, and 32 weeks. Leakage of TNT to seawater and the toxicity to N. spinipes was significantly reduced by sediment burial, especially in fine-grained sediment. Hence, this study suggests that adverse effects of TNT in dumped ammunition on aquatic organisms should be delayed/reduced at low temperature and when TNT is covered sediment, especially with fine-grained sediment.

A practical ranking system to compare toxicity of anti-fouling paints

The toxicity of a number of new anti-fouling paints, claimed to function by physical means and not by leakage of toxic substances, have been tested on two common organisms in the Baltic Sea, i.e., the red macro alga Ceramium tenuicorne and the copepod Nitocra spinipes. In order to compare the toxicity between the paints a ranking system was developed based on the EC 50- and LC 50-values. The results showed a wide span in toxicity with the most toxic paints ranked 160 times more toxic than the ones ranked least toxic. Also, TBT, irgarol and diuron, which have been used as active ingredients in traditional anti-fouling paints, were used to evaluate the sensitivity of the two test organisms. The results showed that the test organisms were equally sensitive to the substances as similar organisms in earlier studies. In conclusion, the ranking system presented in this study permits ranking and comparison of total toxicity of complex mixtures.

Fate and Effects of 2,4,6-Trinitrotoluene (TNT) from Dumped Ammunition in a Field Study with Fish and Invertebrates

2,4,6-Trinitrotoluene (TNT) is the major explosive ingredient in ammunition dumped into lakes and sea after World War II. The aim of the present field study was to study the fate and effect of TNT and its degradation products from dumped ammunition. Artillery shells were cleaved longitudinally to expose TNT and placed in open boxes filled with sediment, and then placed at the sea bottom. Sediment samples were taken in each box at the start and after 3, 9, 13, 20, 24, 33, and 36 months, and the sediments were tested for toxicity with bioassays using Nitocra spinipes (96 h), Hyalella azteca (96 h), and Daphnia magna (24 and 48 h). The result from the bioassays showed no impact of dumped ammunition on the survival of H. azteca and mobility of D. magna. Bioassays with N. spinipes showed significant differences in toxicity between control boxes and boxes with shells after 9 months and thereafter. The mean mortality (+/- SD) of N. spinipes in boxes with shells was 63 +/- 22%, and the mortality in control boxes was 23 +/- 17%. No continuous increase in sediment toxicity over time was found. After 3 years, cages with European flounder (Platichtys flesus) and blue mussels (Mytilus edulis) were attached to the boxes. The fish were examined for biochemical and physiological effects 8 weeks later. Exposure to ammunition, which had rested on the sea bottom 3 years, caused no significant effects on body indices, hematological variables, and detoxification and antioxidant enzymes activities in the flounder. The sediment, bile, and blood plasma of exposed fish, and hepatopancreas of exposed mussels, contained no detectable levels of TNT and its metabolites. Only minor disappearance of TNT from the shells could be detected by visual inspection on site (by scuba divers). This study suggests that the survival of sensitive benthic organisms, e.g., N. spinipes, might be negatively affected at an ammunition dumping site.

Exposure of biofilms to meiofaunal copepods affects the larval settlement of Hydroides elegans (Polychaeta)

This study reports significant differences in larval settlement of the polychaete Hydroides elegans (Haswell, 1883) on biofilms treated either by different densities of live harpacticoid copepods or conditioned by particulate organic material (POM) retrieved from harpacticoid copepod cultures. The copepods used in this study were the facultatively predatory Tisbe japonica and the detritivorous Nitocra spinipes. The resulting biofilms covering experimental surfaces exhibited differences in bacterial abundances, bacterial community profiles and bioactivity, as evidenced by differential attractivity provided as percentages of larval settlement. The density of settled larvae decreased on biofilms modified by increasing numbers of copepods. The highest bacterial densities (16085 ± 915 cells mm -2 ) were found on natural biofilms conditioned with POM from cultures of T. japonica. The lowest bacterial densities (4020 ± 765 cells mm -2 ) were found on biofilms grown in the presence of the highest numbers of live T japonica. Spearman-rank correlation results revealed a positive trend between increasing bacterial densities and larval settlement. Increasing copepod abundances were correlated with reduced bacterial densities and caused changes in the bacterial community profiles, which were identified by terminal restriction fragment analyses. Changes in microbial biofilms due to the conditioning effects of copepods or their remains/exudates are assumed to be responsible for differential larval settlement. Hence, the present laboratory study demonstrates that effects of predators can be mediated by biofilms and affect larval settlement indirectly.

New biocide-free anti-fouling paints are toxic

A number of new anti-fouling paints claimed to be more friendly to the environment, have entered the market since prohibition of biocide containing paints have been enforced in many areas. Leakage waters from five new anti-fouling paints were tested for toxic effects to the macro algae Ceramium tenuicorne and Ceramium strictum and to the crustacean Nitocra spinipes. A banned copper and irgarol 1051 containing anti-fouling paint was used as reference. Five of the six paints tested were toxic to all or some of the organisms after two weeks of leakage with EC50 ranging from 0.08 to around 2% leakage water and LC50 ranging from 1.1% to 88%. The toxicity of leakage water from these paints was still high after 16 weeks. We conclude that these paints contain substances toxic to common organisms in the coastal Baltic ecosystem. A silicone based paint did not exhibit toxic effects to the two organisms. We recommend that biological tests should be used to identify the most harmful products before they are released on the market.

Effects of three PBDEs on development, reproduction and population growth rate of the harpacticoid copepod Nitocra spinipes

The current knowledge concerning effects of polybrominated diphenyl ethers (PBDEs) on aquatic organisms is very limited. A full life-cycle (⩽26 days exposure) ecotoxicity test with the particle-feeding copepod Nitocra spinipes was therefore used to study effects of BDE-47, -99 and -100 on larval development rate (LDR) and population growth rate ( r m). LDR significantly decreased in copepods exposed for 6 days to nominal concentrations ⩾0.013 mg/l BDE-47 and ⩾0.03 mg/l BDE-99. Large concentration ratios (⩽338) between adult acute and juvenile subchronic endpoints were observed. Exposure over the full life cycle (⩽26 days) showed that r m in general was a less sensitive endpoint than LDR. Still, the r m in copepods exposed to 0.04 mg/l BDE-47 was significantly reduced compared to the controls (*** P<0.001). Partitioning experiments with 14C-BDE-47 and 14C-BDE-99 in the test system showed that the major fractions (∼50–80%) were associated to particulate material. Our findings indicate that development and reproduction in N. spinipes are sensitive to the tested PBDEs and that ingestion of particle-adsorbed PBDEs most likely is the predominant route of exposure in N. spinipes. However, to further improve the usefulness of laboratory effect levels of PBDEs and other lipophilic substances for environmental risk assessment, it is important to develop ecotoxicological tools, which can evaluate and rate the toxic contribution from different matrices, such as suspended particles, sediment, food, water etc.