Ichiro Takeuchi

Bioconcentration and biomagnification of polybrominated diphenyl ethers (PBDEs) through lower-trophic-level coastal marine food web.

Bivalves, crabs, fishes, seawater, and sediment collected from the inner part of Tokyo Bay, Japan, were measured for 20 polybrominated diphenyl ether (PBDE) and 5 polychlorinated biphenyl (PCB) congeners. To determine the trophic levels of the organisms, carbon and nitrogen stable isotope ratios (delta(13)C and delta(15)N) were also measured. Bioconcentration factors of PBDE and PCB congeners increased as the octanol-water partition coefficient (K(ow)) rose to log K(ow)=7, above which they decreased again. Biomagnification of PCBs and several PBDE congeners (BDE47, 99, 100, 153 and 154) up the trophic ladder was confirmed by a positive correlation between their concentrations and delta(15)N. Other PBDE congeners showed a negative or no correlation, suggesting their biotransformation through metabolism. The more hydrophobic congeners of both PBDEs (Br=2-6) and PCBs (Cl=6-9) were biomagnified more. It thus appears that PBDEs are less biomagnified than PCBs.

Differences in the acute toxicities of tributyltin between the Caprellidea and the Gammaridea (Crustacea: Amphipoda)

Tests for the acute toxicity of tributyltin (TBT) were conducted on amphipod crustaceans collected from Otsuchi Bay, Japan. Five species of caprellids and three species of gammarids, which belong to a closely related ecological niche, were used for the exposure experiments at seven test concentrations (0, 0.001, 0.01, 0.1, 1, 10 and 100 microg TBTCl/l) for 48 h at 20 degrees C. The 48-h LC50 values of the caprellids were 1.2-6.6 microg TBTCl/l, and these were significantly lower than those of the gammarids (17.8-23.1 microg TBTCl/l). This suggests that caprellids are more sensitive to TBT than gammarids. Furthermore, the proportions of TBT and its derivatives, dibutyltin (DBT) and monobutyltin (MBT), were measured in the amphipods collected from Otsuchi Bay. In the caprellids, TBT was the predominant compound, accounting for 72% of the total butyltin which reflected the butyltin ratio in seawater, while in the gammarids, TBTs breakdown products (DBT and MBT) predominated, accounting for 75% of the total butyltin. This difference suggests that caprellids may have lower metabolic capacity to degrade TBT than gammarids. Therefore, the difference in sensitivity to TBT among the amphipods is thought to be related to the species-specific capacity to metabolize TBT.

Is the Caprellidea a monophyletic group

Cladistic analysis of caprellidean genera has revealed major divergence near the outgroup producing two major lines of evolution: Pseudoprotomima-Perotripus, and Caprogammarus-Caprella. The most plesiomorphic genus of each line, Pseudoprotomima and Caprogammarus, respectively, shows different plesiomorphic characters to each other. Pseudoprotomima has pereopods III and IV with 6 articles, antenna II flagellum with > 2 articles and three pairs of gills, while Caprogammarus has an abdomen 5-segmented with three pairs of pleopods. Pseudoprotomima and related genera are distributed from the temperate regions of the northern hemisphere to the South Indian Ocean, while Caprogammarus and related genera are recorded primarily from the boreal region of the northern hemisphere. That pereopods III and IV in Pseudoprotomima and its relatives have 6 articles indicates the functional gap from the Podoceridae (Gammaridea)-Caprogammaridae-Caprellidae gradation, since in the Podoceridae to the Caprellidae these pereopods ...

Caprella watch ; a new approach for monitoring butyltin residues in the ocean

A comparative study on the butyltin levels in various organisms showed that marked bioaccumulation occurs in certain lower trophic levels; i.e. from seawater to phytoplankton and into caprellid amphipods, Caprella spp. Caprella spp., which inhabit algal communities and aquaculture beds in the subtidal zone, are small crustaceans with reduced movement and a life-span of less than 3 months. These characteristics indicate that Caprella spp. may be well-suited for monitoring butyltin residue changes over small spatial and temporal scales. Two groups of organisms, mussels and neogastropods, have been mainly used for monitoring butyltin in shallow water ecosystems. These invertebrates mainly inhabit the intertidal zone where the butyltin levels vary widely depending on the immersion period and exposure to the sea surface microlayer. Monitoring using neogastropods may also over estimate exposures after restrictions on tributyltin, since neogastropods show an irreversible response to residue changes owing to their long life-spans. Thus, we propose usage of Caprella spp. to monitor temporal and spatial changes in baseline concentrations of butyltins.

Growth and reproduction of the epifaunal amphipod Caprella okadai Arimoto (Crustacea : Amphipoda : Caprellidea)

Abstract Growth, maturation and reproduction of Caprella okadai Arimoto, an amphipod crustacean endemic to the Japanese coast, were studied under laboratory conditions at 20°C, and 14 h light: 10 h dark photoperiod. The diatom Cylindrotheca closterium (Ehrenberg), and the red alga Gelidium amansii (Lamouroux) were provided for food and clinging substratum. Juveniles newly emerged from the brood pouch molted at 2.9–6.8-day intervals. Body lebgth increased per instar of both males and females represented a sigmoid curve. On average, females reached sexual maturity at instar VII at 20.1 days of age, produced their first brood at 20.6 days, and had 3.8 successive cutches at 5.0–6.0-day intervals. The number of embryos per brood increased from 10.8 at instar IX. A female produced an average of 36.1 offspring throughout her life span. The similarity of life history patterns of C. okadai and C. Danilevskii Czerniavski indicates that habitat segregation of these two species results from morphologicaal adaptations of caprellids to their respective localities.

The Caprellidea (Crustacea: Amphipoda) from Tasmania

The taxonomy of the Caprellidea from the Tasmanian coast is reviewed with data on species composition and biogeographical characteristics. Four new species, Caprella edgari n. sp., Hircella inermis n. sp., Orthoprotella tuberculata n. sp. and Paraproto tasmaniensis n. sp. are described, and detailed descriptions of Caprella acanthogaster Mayer, 1890, Orthoprotella tasmaniensis Guiler, 1954 and Paraproto spinosa (Haswell, 1885) are provided. Lateral view figures of the 18 species found in Tasmanian waters until now, with a key to species level, are also given. The species diversity of littoral caprellids from Tasmania is considerably high when compared with other regions of similar latitude in the southern hemisphere, probably due to the warm effect of the East Australian current passing down towards the east coast of Tasmania. This fact, with previous studies on the low concentrations of dissolved nutrients in rivers and dark tannin-stained waters on the west coast, could result in species richness and abundance being clearly higher on the east coast of Tasmania.

Regional variations in trace element concentrations in tissues of black tiger shrimp Penaeus monodon (Decapoda: Penaeidae) from South Vietnam

The goal of the present study was to examine the specific bioaccumulation of 22 trace elements in muscle, exoskeleton and hepatopancreas of black tiger shrimp Penaeus monodon from the Mekong River Delta (MRD), and the South Key Economic Zone (SKEZ), South Vietnam. The general tendency in most trace element concentrations among different tissues were hepatopancreas>exoskeleton>muscle. Comparisons of trace element levels in tissues between the two regions showed that concentrations of Se in muscle and As in all three tissues were higher in SKEZ; whereas in MRD, the higher concentrations of most elements such as Mn, Cu, Cd, Ba, Hg, were observed in tissues. These geographical variations in trace element levels may reflect the differences in human activities between the two regions of South Vietnam. The target hazard quotient (THQ) values for trace elements (<1) indicate that local residents are not exposed to potential health risks via the consumption of shrimp.

Active erosion of Undaria pinnatifida Suringar (Laminariales, Phaeophyceae) mass-cultured in Otsuchi Bay in northeastern Japan

Abstract Production and erosion of the commercially mass-cultured kelp Undaria pinnatifida Suringar f. distans Miyabe et Okamura were investigated between January and April 1998 in Otsuchi Bay, ca. 8 km long and 2 km wide, located on the northeastern coast of Japan. Steady growth in total kelp length was observed from January to March, with rates of 1.1 to 1.8 cm day −1 . Erosion rates were consistently low at −1 in January and February, but increased to 0.5 cm day −1 in March, and were comparable to the growth rate in April. Biomass erosion represented 30–40% of production in March and over 80% in April. The greater erosion in April was attributed to a low supply of dissolved inorganic nitrogen and aging of the alga. Total net production of the cultured kelp in the bay was 49.5 tonne C, of which, 81% (38.7 tonne C) was harvested while 19% (10.8 tonne C) was lost due to erosion. In terms of nitrogen, 33% of total production (4.68 tonne N) was eroded, while 67% was harvested. Active erosion of the kelp thus appears to be an important source of organic matter for heterotrophic processes in the coastal waters of eastern Asia where kelp cultivation is a major aquaculture industry.

Duration and size of embryos in epifaunal amphipods Caprella danilevskii Czerniavski and C. okadai Arimoto (Crustacea:Amphipoda:Caprellidea)

Abstract Embryonic duration in two species of epifaunal caprellid amphipods, Caprella danilevskii Czerniavski and Caprella okadai Arimoto, was investigated. The duration decreased from 13 days at 10°C to 3.5 days at 24°C in C. danilevskii and 8.2 days at 12°C to 3.4 days at 24°C in C. okadai . The embryonic duration can be expressed using Belehradeks equation which indicates “biological zero”, α, at 5.5°C in C. danilevskii and 6°C in C. okadai . The generation period of both species was estimated based on Belehradeks equation of embryonic development and the generation period at 20°C obtained in our previous studies; 53.2 days at 12°C to 20.8 days at 24°C in C. danilevskii , 54.9 days at 12°C to 20.4 days at 24°C in C. okadai . Embryo size was also noted during field collections; C. danilevskii embryos increased from 0.40 × 0.33 mm in the early stage to 0.46 × 0.37 mm in the late stage and C. okadai from 0.34 × 0.28 mm to 0.37 × 0.30 mm.

Biomagnification profiles of tributyltin (TBT) and triphenyltin (TPT) in Japanese coastal food webs elucidated by stable nitrogen isotope ratios

The measurement of organotins in the various biotas of coastal food webs with stable nitrogen isotope ratios (delta(15)N), which increase 3.4 per thousand per trophic level, can provide a biomagnification profile of organotins through food web. In this study, various biological samples were collected from three localities in Western Japan between 2002 and 2003 for analyses. Tributyltin (TBT) and triphenyltin (TPT) were still detected with a maximum of 99.5 and 8.7 ng wet weight g(-1), respectively. Unlike TBT, significant biomagnification of TPT through the food web (expressed by delta(15)N) was found in all three localities. The log transformed octanol-water partition coefficient (log K(ow)) of TPT of 2.11-3.43 was overlapped by, but was slightly lower than, that of TBT of 3.70-4.70. Thus, this study demonstrates that although these chemicals have a log K(ow) lower than 5, at least TPT undergoes significant biomagnification through the food web.