24Aluminum coagulants are widely used in water treatment plants to remove turbidity and 25 dissolved substances. However, because high aluminum concentrations in treated water are 26 associated with increased turbidity and because aluminum exerts undeniable human health 27 effects, its concentration should be controlled in water treatment plants, especially in plants 28 that use aluminum coagulants. In this study, the effect of polyaluminum chloride (PACl) 29 coagulant characteristics on dissolved residual aluminum concentrations after coagulation and 30 filtration was investigated. The dissolved residual aluminum concentrations at a given 31 coagulation pH differed among the PACls tested. Very-high-basicity PACl yielded low 32 dissolved residual aluminum concentrations and higher natural organic matter (NOM) removal. 33The low residual aluminum concentrations were related to the low content of monomeric

Hybridization has been frequently observed among 3 species of greenlings (genus Hexagrammos) common in waters off Japan. In order to estimate the frequency of hybridization events from egg masses collected from male territories, efficient maternal identification of numerous egg masses is required. A novel streamlined approach for maternal identification of 3 Hexagrammos spp. was developed using multiplex amplified product length polymorphism (APLP) analysis of the mitochondrial cytochrome b (Cytb) and the 12S and 16S ribosomal RNA (12-16S rRNA) regions. Concurrent use of species-specific primer sets permits the amplification of different-sized PCR products, diagnosing each species through one procedure of PCR in a single reaction tube. The APLP method produced more rapid, reliable, and cost-efficient species identifications compared to those from an established restriction fragment length polymorphism (RFLP) protocol.

In coastal areas in Japan, three species of greenling (Hexagrammos spp.) can hybridize. In a natural reef setting we showed that Hexagrammos agrammus and H. octogrammus established their breeding territories in a shallow area where seaweed was abundant, whereas H. otakii established breeding territories in a deep area that was sparsely covered with seaweed. This difference in habitat use resulted in H. otakii being distributed separately from the other two species, thereby reducing the potential for hybridization. However, all the three species co-occurred in an artificial area near a breakwater. This area is characterized by steep slopes and complex stacked concrete structures, which create a mosaic-habitat consisting of a shallow environment with seaweed and a deep environment with sparse seaweed, allowing the three species to breed within a single area. Our results suggest that man-made structures can create an artificial mosaic-habitat that can disrupt habitat isolation and promote hybridization between species.

Habitat use and spawning substrata were surveyed to characterize the contribution of habitat divergence to reproductive isolation in greenling Hexagrammos species. The spawning substrata and microhabitat in breeding territories differed amongst the three Hexagrammos species studied: H. octogrammus, H. agrammus and H. otakii used small red algae, surfgrass and bryozoans, respectively, as spawning substrata, and breeding territories were established in areas where those substrata were abundant. In contrast, non-territorial individuals were observed in a comparatively wider range of habitats than conspecific territories. Consequently, the distributions of non-territorial individuals of the three species partially overlapped. Since hybrids have been frequently collected, the difference in spawning substrata and the subsequent microhabitat divergence in breeding territories do not prevent females from encountering males of other species. Thus, in addition to habitat divergence, other factors such as behavioural differentiation may be needed to complete premating reproductive isolation amongst these three Hexagrammos species.

The ability of in-line coagulation pretreatment with high-basicity polyaluminum chloride (PACl) coagulants to enhance virus removal by ceramic microfiltration was examined by comparing virus removal efficiencies from water pretreated with PACl-2.2 (basicity 2.2) and PACl-2.5 (basicity 2.5) versus alum, a synthetic aluminum chloride (AlCl 3 ) solution, and two commercially available PACls, PACl-1.5 and PACl-1.8. The virus removal ratios for AlCl 3 , alum, PACl-1.5, and PACl-1.8 decreased markedly when the pH of the treated water shifted from 6.8 to 7.8, but was high at both pHs for PACl-2.2 and PACl-2.5. PACl-2.5 contains Al 13 species and possibly Al 30 species, and has a high colloid charge density. It removed viruses more efficiently than the other aluminum-based coagulants, not only at neutral pH, but also under weakly alkaline conditions. Moreover, the in-line coagulation-ceramic microfiltration process with PACl-2.5 pretreatment removed not only viruses but also dissolved organic carbon and UV260-absorbing natural organic matter more efficiently and resulted in a lower residual aluminum concentration than did commercially available PACls, especially under weakly alkaline conditions. A combination of coagulation pretreatment with a high-basicity PACl and ceramic microfiltration can provide effective treatment of drinking water over a broader pH range than is possible with commercially available aluminum-based coagulants.