5), but after 10 min, their relative distribution already changed substantially. In particular, 51.8 ± 19.3% of copepods were located
in the area with the DD-containing agarose (+), 37.6 ± 10.9% were in the middle (0), and 10.6 ± 10.0% were in the area with the agarose without DD (−). Values in the area with the DD-containing agarose (+) and without DD (−) were significantly different (One-way Anova, F2,6 = 6.644, p < 0.05, Tukey's Post Test, p < 0.05), IDH inhibitor thus suggesting that the copepods were showing a preference for the portion of the vessel that contained the DD. This attraction was more evident at t = 30 min, when the copepod distribution increased significantly in (+) (63.7 ± 18.0%), compared to both (0) (19.2 ± 12.2%) and (−) (17.0 ± 8.9%) (One-way Anova, F2,6 = 11.28, p < 0.01) ( Fig. 5). The relative distribution of T. stylifera did
not change throughout the experiment, although the highest percentage of copepods in (+) was recorded after 120 min (72.2 ± 10.7%). In this study, female T. stylifera filtration and ingestion rates on P. minimum increased in the presence of DD, even if the differences were significant SB431542 manufacturer only in the case of filtration rates. P. minimum is known to be well ingested by T. stylifera ( Barreiro et al., 2011 and Turner et al., 2001) and other copepods ( Liu et al., 2010). Our ingestion rates are comparable to those measured in previous studies by Turner et al. ( Turner et al., 2001). These authors observed an increase in T. stylifera ingestion rates on the diatom Thalassiosira rotula in a mixture with P. minimum. They are also in agreement with another study using a mixed diet of DD-encapsulated liposomes and P. minimum where fecal pellets (an indirect measure of feeding activity) were found to increase in both T. stylifera and the copepod Calanus helgolandicus ( Buttino et al., 2008). It is unclear why T. stylifera fed more on P. minimum in the presence
of PUAs. PUAs liberated from diatom biofilms have been reported to be repellent to several copepod and cladoceran species ( Jüttner, 2005). C. pacificus seems to avoid the most potent aldehyde producers in nature ( Leising et al., 2005). More recently, Michalec et al. (2013) have shown that pollutants such as Polycyclic Aromatic Hydrocarbons (PAHs) induced hyperactivity in the estuarine copepod Eurytemora affinis, Amino acid with an increase in swimming speed and activity resembling an escape reaction permitting copepods to evade stressful conditions. Further studies testing the effects of DD on the three-dimensional swimming behavior in Pseudodiaptomus annandalei indicated that males and ovigerous females swam faster at higher concentrations, suggesting a complex mode of action of this toxin ( Michalec et al., in press). T. stylifera is reported as being non selective in its feeding behavior and, according to Barreiro et al. (2011), seems to be unaware of the toxicity of its food since T.