Zoological Studies/動物研究學刊
中央研究院生物多樣性研究中心,正常發行
選擇卷期
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Calanus sinicus is a calanoid copepod and dominant zooplankton species in the coastal waters of the western North Pacific rim. We examined the effects of different food concentrations on the swimming behavior of this species. Adults were video-recorded at 30 frames/s using video equipment that allowed us to follow each freely swimming individual continuously in 1L containers (10 × 10 × 10 cm) with 30 PSU salinity filtered seawater at 20°C. Several behavioral parameters such as swimming trajectories and speed showed distinct changes under different food conditions. The dynamics of swimming states were assessed by the statistical properties of their trajectories. Slow swimming was generally the dominant behavior. Swimming path trajectory decreased at high food concentrations and swimming path entropy decreased when the food concentrations increased.
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Elisesione imajimai sp. nov. is newly described based on specimens collected in Sagami Bay, Japan, at a depth of 150-250 m. This new species resembles E. problematica (Wesenberg-Lund, 1950) from Iceland, but differs because in E. imajimai sp. nov. the ventral cirri surpass the tips of the neurochaetal lobes, reaching to the medial part of the neurochaetal bundle; the palps are 1/2-4/5 as long as the antennae; the aciculae are pale brownish; and the dorsal integument shows 9-10 transverse wrinkles per segment, whereas in E. problematica the ventral cirri hardly reach the tips of the neurochaetal lobes; the palps are as long as the antennae; the aciculae are black; and there are 15 transverse wrinkles per segment. A morphological redescription of E. problematica based on its type material and a revised key to identify species in the genus are also provided. A phylogenetic analysis based upon four genes (COI, 16S, 18S, 28S) confirms its position within Hesionini.
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Little is known about the growth rates of invertebrates living in ordinary deep-sea habitats such as continental slopes. Thus, the growth rates of two species of the deep-sea scalpellid barnacles, Scalpellum stearnsii and Graviscalpellum pedunculatum, were studied in two aquaria (at Nara and Okinawa Churaumi, Japan). In addition, growth of an S. stearnsii individual after 1 year of deployment was measured in the field. Overall, adult individuals of both species showed slow growths over 8 months (at Nara) and 2 years (at Okinawa) of rearing (e.g., at Nara: 2.0 ± 3.6 μm d^(-1) for S. stearnsii and 5.9 ± 2.7 μm d^(-1) for G. pedunculatum; mean ± SD). In contrast, growth rates of juvenile S. stearnsii at Nara were greater (15 ± 7.7 μm d^(-1)). The in situ growth rate of the adult S. stearnsii (3.4 μm d^(-1)) was greater than the average, but within the range of the rates of similar-sized individuals recorded in aquaria. Compared with other pedunculate barnacles, both species show small growth rates typical for deep-sea animals.
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Birds show considerable variation in egg size, both within and between clutches. There are many factors affecting egg dimensions including features of the birds themselves, territory quality, food abundance and weather conditions. One feature that varies in clutches is repeatability of egg dimensions within a clutch. We studied variation in egg size in clutches of the Red-backed Shrike Lanius collurio in east-central Poland and examined the effects of territory quality and weather conditions on egg size repeatability. Repeatability of egg size was low and ranged from 0.51 to 0.55. No significant differences in egg dimensions were found between clutch size classes (3 to 7 eggs, modal clutch size of 6). Weather conditions only influenced repeatability of egg volume. This parameter was affected by the year and one environmental factor - total rainfall immediately before egg laying. With increasing rainfall, the repeatability of egg volume decreased. Weather conditions can influence food availability and in this way also affect egg size. The Red-backed Shrike diet consists mainly of insects, the activity of which significantly decreased during rainfall. In such conditions, birds have to spend more energy to gain food, which could consequently lead to differences in egg size.
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Cetacean habitat use based on different environmental phases varies between species and geographies, and little is known about Pacific humpback dolphin habitat use in the Beibu Gulf. Here we aimed to identify seasonal, lunar and tidal influences on the spatial use of Beibu humpback dolphins based on two parameters: water depth and distance to an estuary. The ANOVA test indicated that habitat use was influenced by seasons and tidal phases, but not lunar phases. The humpback dolphins utilized shallow areas near an estuary throughout the wet season and high tides, and moved toward deeper water during the dry season and low tides. This habitat preference is likely synchronized with prey seasonal and tidal movements. The wet season and high tides bring abundant prey resources and increase accessibility to inshore shallow waters for humpback dolphins. The present study provides new information on regular habitat use by Indo- Pacific humpback dolphins, which is crucial for developing effective conservation strategies.
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The family Nemesiidae is the second most diverse family of Mygalomorphae spiders. Acanthogonatus centralis (Nemesiidae) is commonly found in hilly areas of central Argentina. These spiders are considered generalists due to their basal position in the phylogeny, but little is known about the trophic ecology of the species. Therefore, the objectives of this study were to study some of the species' predatory traits, such as feeding frequency and prey acceptance, and to assess its natural diet. In addition, two parameters - attack latency and consumption time - were measured for each accepted prey. We found that A. centralis feeds every two days and accepts almost all prey offered. The most accepted prey items were beetle larvae and termites. In fact, termites were attacked faster than any other prey, suggesting they are a suitable prey for these spiders. In regard to the species' natural diet, we found remains of seven prey items, ants and beetles being the most frequent. In this study, we found that Acanthogonatus centralis is polyphagous since it accepts different kinds of prey.
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This paper deals with the efficiency of cultivation media in recovering the species diversity of naked lobose amoebae. A total of 24 species belonging to ten families were isolated with six enrichment media (two liquid and four agar media) during a two-year study on naked lobose amoebae in a branch of the Danube River in Bratislava (Slovak Republic). The highest efficiency was seen in the grass-seed infusion, grass-seed agar, and non-nutrient agar, with 79%, 67%, and 58% of species recovered, respectively. The grass-seed infusion yielded the highest numbers of Thecamoebidae, Vannellidae, Mayorellidae and Dermamoebidae species and is likely the most suitable medium for their recovery. The most effective media were based on grass-seed infusions, which are easy to prepare and suitable for studying the diversity and ecology of naked amoebae from freshwater samples.
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There are many islands in the Iranian waters, but little is known about their coral species. This is a first attempt to describe and illustrate the coral species occurring in Abu-Musa and Sirri Islands. Overall, 26 species belonging to 9 families are reported, and three unidentified species and two species are added to coral communities of Iran. This study also provides overall insight on coral fauna in the Persian Gulf.
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Seven new atyid shrimp species of the genus Caridina H. Milne Edwards, 1837 are described from southern China: C. longshan sp. nov., C. alu sp. nov., C. spinicrus sp. nov., C. beiliu sp. nov., C. jiangkou sp. nov., C. guilin sp. nov. and C. laticarpalis sp. nov. Descriptions and figures for all taxa are provided, and taxa are compared with their closest congeners. An updated list of all cave atyid and palaemonid shrimp species found in China is provided. Caridina semiblepsia Guo, Choy and Gui, 1996 is here regarded as a junior subjective synonym of C. ablepsia Guo, Jiang and Zhang, 1992. One poorly known species, Typhlocaridina linyunensis Li and Luo, 2001, described from a cave in Guangxi is here shown to be a palaemonid instead of an atyid, and is actually the senior synonym of Macrobrachium lingyunense Li, Cai and Clarke, 2006.
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Surveys of octocorals from Dongsha Atoll, Taiwan were conducted during 2011, 2013 and 2015 by SCUBA at a depth range of 6-25 m. The collections yielded ~540 specimens, encompassing the variety of taxa occurring in the explored sites; estimates of their abundances were also recorded. Dongsha features a highly diverse octocoral fauna, and octocorals are the dominant benthic organisms in the surveyed reef sites, often covering the majority of the hard substratum. Specimens were identified to the genus and species levels based on an iterative approach that integrates classical taxonomy with character-based molecular barcodes. A total of 51 nominal species representing 20 genera belonging to seven families were recorded, plus ~30 colonies that could only be assigned to a genus. Members of the family Alcyoniidae were the most abundant and diverse taxa, with 27 nominal species plus at least one potentially new, undescribed species of Sinularia, and 5-7 species each of Cladiella, Lobophytum and Sarcophyton. Problems with the taxonomic identification and phylogenetic relationships of species in these genera are discussed. The peculiarity of the Dongsha octocoral species composition is noted, and the composition is also compared to the other Taiwanese reef systems.