Kazumi Tanida

Freshwater biomonitoring with macroinvertebrates in East Asia

This paper summarizes the history and current status of efforts to implement macroinvertebrate biomonitoring protocols for surface water pollution in China, Japan, South Korea, Malaysia, Mongolia, Russia (Far East), and Thailand. Impediments to biomonitoring in some of these countries include: (1) lack of knowledge about macroinvertebrate fauna and their tolerance values, especially during the aquatic, immature stages; (2) the scarcity of research programs and formal training opportunities for biomonitoring offered in universities; (3) the shortage of high-quality microscopes and other necessary equipment; and (4) limited government understanding and support for biomonitoring, few skilled regulatory staff, and the persistence of old and unusable biomonitoring protocols. A recently established regional network, the Aquatic Entomological Society of East Asia (AESEA), and several major recent publications are helping to coordinate and promote science and technology in East Asia.

Drift patterns of particulate matter and organisms during artificial high flows in a large experimental channel

Using a large experimental channel, five artificial high flows with different flow regimes were launched to reveal the precise temporal sequences of drifting particulate matter and organisms during the high flows. Drifting fine particulate matter and organisms were collected by sampling bottles and a water pump, respectively. The peaks of drift abundance occurred before the peak discharges, and the abundance declined quickly within several minutes during the rising phase of high flows. The major determinant of drift abundance of particulate matter and organisms was periods of stable conditions before each high flow (tested by determination coefficients in a correlation analysis). The drift of macroscopic plant material also accelerated the drifts of epiphytic fauna and infauna, which drifted with plants and bed sediments. The magnitude (discharge and duration of peak flows) of high flows only slightly affected drift abundance. The fauna more resistant to high flows were invertebrates that fasten their cases or retreats by silk threads on the substrata. Invertebrate taxa having sucking apparatus or high swimming activity were also resistant to high flows.

A Simple Acrylate Fiber Sampler for Stream Periphyton.

河川などの石礫付着藻類の現存量の指標として頻繁に使われているクロロフィル色素の定量的採取法として,ミクロクロス(アクリル特殊繊維)を用いた方法を開発した。従来の歯ブラシによる方形枠の剥ぎとり法と本法とを比較した結果,実用的には同一の測定値が得られることが確認された。この方法は,現場における採取の手間が少ないうえに,色素定量に先立つ濾過あるいは沈澱操作が不要で,著しく効率のよい方法であった。大量の標本を処理する必要のある藻類の微細分布調査などには,とくに適していると思われる。

Genera and species of Baetidae in Japan: Nigrobaetis, Alainites, Labiobaetis, and Tenuibaetis n. stat. (Ephemeroptera)

We describe morphological characters of the genera Nigrobaetis, Alainites, Labiobaetis, and Tenuibaetis n. stat. and provide generic situations of six Japanese species: Nigrobaetis chocoratus n. comb., N. sacishimensis n. comb., Alainites atagonis, A. florens, A. yoshinensis, and Tenuibaetis pseudofrequentus. To evaluate the polarities of the morphological characters and the monophyly of Nigrobaetis, Alainites, Labiobaetis, and Tenuibaetis, character states of these four genera were compared with the genus Cloeon as an outgroup. Labiobaetis is considered to be a monophyletic group supported by a wide paraglossa. Tenuibaetis is a monophyletic group that is distinguishable from the related genera by robust setae with a medial ridge on the dorsomedian surface of the nymphal femur. We did not find any synapomorphic characters of Nigrobaetis or Alainites. Although we tentatively treat Nigrobaetis and Alainites as distinct genera, they are considered to be paraphyletic taxa.

Responses of benthic invertebrates in an experimental channel to artificial flushes

A large experimental channel was used to examine the responses of benthic invertebrate communities to artificial flushes. Two artificial flushes were done at a 20-day interval with a 2-fold difference in peak discharge and duration between them. The effects of the flushes on macroinvertebrates were monitored by comparing the abundance of individual taxa, taxon richness, diversity measures, and similarity indices. Taxon richness and abundances of invertebrates were drastically reduced by every flush. However, the diversity of invertebrates was not significantly reduced by the flushes, and the composition was similar before and after each flush. The fast recruitment of some taxa, having short life cycles, reduced the diversity of invertebrates in the interval between the two flushes. The flushes caused significant reductions in the abundance of epiphytes and fauna living in the streambed. The fauna more resistant to flushes were invertebrates that fasten their cases or retreats by silk threads to substrata. Taxa living in sediment under stones and having a sucking apparatus were also resistant to flushes.

Isolation of sperm vesicles from adult male mayflies and other insects to prepare high molecular weight genomic DNA samples

We describe here a simple and efficient protocol for genomic DNA isolation from adult males of insects: e.g., Ephemeroptera, Odonata, Orthoptera and Dictyoptera. To minimize contamination of external DNA source, the sperm vesicles were isolated from male individuals from which high molecular weight genomic DNA was extracted. According to this protocol, the genomic DNA samples obtained were high quality (intact), and abundant enough for genotyping analyses and molecular cloning. The protocol reported here enables us to process a huge number of individuals at a time with escaping from cross-contamination, and thus it is quite useful for conducting genetic studies at least in some species of insects. The large yield of high molecular weight DNA from single individual may be advantageous for non PCR-based experiments. As a case study of the protocol, partial coding sequences of histone H3 and EF-1α genes are determined for some insects with PCR-amplified DNA fragments.

Larval growth and development in the caddisfly Cheumatopsyche brevilineata under natural thermal regimes

Cheumatopsyche brevilineata (Iwata) is a filter‐feeding caddisfly without distinct or distinguishable cohorts. In a semi‐natural channel, we reared fourth and fifth instar larvae of C. brevilineata in individual cages with hourly recording of water temperature. We calculated the individual growth rate from the wet‐weight gain of each larva, and the development rate from the ratio of larvae that progressed to the next instar or pupal stage during each rearing experiment. We analyzed the linear regressions of growth (increase in size) and development (physiological and morphological progression toward maturity) rates against the statistical parameters of water temperatures during each rearing period, i.e. mean and given percentiles of water temperatures. We presumed that the most appropriate parameter of water temperature to explain larval growth and development would show a peak value of the determination coefficients (r2) in the linear regressions. There were highly significant regressions in the growth rates for fourth and fifth instar larvae and in development rates for fourth instar larvae against every statistical parameter of water temperature, but not in the development rates for fifth instar larvae. For the growth of fourth and fifth instar larvae, we could not specify the most appropriate parameters of water temperatures, because we observed no clear peaks in the determination coefficients. For the development of fourth instar larvae, this parameter could be the 65th percentile value, where the development zero temperature and effective degree‐days were 11.1°C and 56 degree‐days, respectively.

Conditions of establishment for the Salix community at lower-than-normal water levels along a dam reservoir shoreline

In limited-water-level reservoirs, areas along the reservoir shoreline are often exposed within the drawdown zone when water levels are reduced from normal to limited levels during the flood season. To prevent erosion and conserve the landscape, test plantings and landscaping along the shoreline have been implemented at some dam reservoirs. The establishment of vegetation within the drawdown zone contributes to both landscape and wildlife habitat conservation. Distribution, habitat, and seed-dispersal period of willows such as Salix subfragilis were investigated at Miharu Dam reservoir in northeastern Japan. Eight willow species were found around the dam, but S. subfragilis dominated within the drawdown zone. Field survey results beginning in 1995 indicate that the size of the S. subfragilis community increased after initial impoundment. Although many other Salix species disperse seeds prior to the drawdown period, S. subfragilis disperses during and after drawdown in the spring; thus, when water levels are lower than normal, its seeds are supplied to the newly exposed zones that provide suitable habitat for Salix seedling establishment. Our results suggest that S. subfragilis dominated because of water-resistant properties and timing of the seed dispersal period.

Labiobaetis species of Japan, Taiwan, and Korea, with a new synonym of L. atrebatinus (Eaton 1870) and reerection of the subspecies L. atrebatinus orientalis (Kluge 1983) (Ephemeroptera, Baetidae)

We associated nymphs of Labiobaetis sp. G and Labiobaetis sp. Q from Japan with imagoes reared from nymphs in the field. Labiobaetis sp. G was identified with L. atrebatinus (Eaton 1870) based on characters of the reared male and female imagoes, nymphs, and eggs. We also synonymized a Taiwanese species, L. morus (Chang and Yang 1994), with L. atrebatinus. After further examination of the characters of male imagoes from Japan and Korea and nymphs from Japan and Taiwan, we found them to be correspondent to subspecies L. atrebatinus orientalis (Kluge 1983). Thus, we reerected the subspecific status of L. a. orientalis, although it had been considered not distinguishable from the nominotypical subspecies L. a. atrebatinus. Labiobaetis a. orientalis is distributed in the Russian Far East, Japan, Korea, and Taiwan. We identified Labiobaetis sp. Q with L. tricolor (Tshernova 1928) based on characters of the reared male and female imagoes, nymphs, and eggs. Labiobaetis tricolor was recorded from Japan for the first time.

First record of Baetis taiwanensis Müller‐Liebenau from Japan, with description of the imago and subimago (Ephemeroptera: Baetidae)

Baetis taiwanensis is recorded from Japan, and its imagoes and subimagoes are described for the first time. We provide diagnostic characters which are useful to distinguish B. taiwanensis from an allied species, Baetis sahoensis, in imago, subimago and nymph. We reveal that the line drawings of B. taiwanensis and Nigrobaetis tatuensis were inadvertently interchanged in the original description.