Xiaozhong Hu

An approach to analyzing spatial patterns of planktonic ciliate communities for monitoring water quality in Jiaozhou Bay, northern China.

Spatial patterns of planktonic ciliate communities for assessment of marine environmental status were studied from June 2007 to May 2008 in Jiaozhou Bay, Qingdao, northern China. Ciliate communities were sampled biweekly at five sampling sites with a spatial gradient of environmental stress. Multivariate/univariate analyses demonstrated that: (1) the planktonic ciliate community structures represented significant differences among the five sites; (2) spatial patterns of the ciliate communities were significantly correlated with environmental variables, especially the nutrients nitrate nitrogen (NO₃-N) and soluble reactive phosphates (SRP); (3) five dominant species (e.g., Rimostrombidium veniliae, Strombidium capitatum, Mesodinium pupula and Strombidinopsis acutum) were significantly correlated with nitrogen and/or SRP; and (4) both species richness and species diversity indices were correlated with NO₃-N and salinity. These results suggest that planktonic ciliated protozoa might be used as a robust bioindicator of marine water quality.

Planktonic protist communities in a semi-enclosed mariculture pond: structural variation and correlation with environmental conditions

In order to evaluate the environmental status within a mariculture pond, temporal variations of physico-chemical factors, protist community structure and interactions between biota and environmental conditions were investigated during a complete cycle in semi-enclosed shrimp-farming waters near Qingdao, north China. Results revealed that: (1) a total of 54 protist taxa with ten dominant species was present, comprising 4 chlorophyceans, 2 chrysophyceans, 5 cryptophyceans, 10 dinoflagellates, 3 euglenophyceans, 10 diatoms, 18 ciliates and 2 sarcodines; (2) a single peak of protist abundance occurred in October, mainly due to the chlorophyceans, diatoms and chrysophyceans, while the bimodal peaks of biomass in July and October were mainly due to the ciliates, dinoflagellates and diatoms; (3) the succession of protist communities significantly correlated with the changes of nutrients, salinity and temperature, especially phosphate, either alone or in combination with NO 3 ; (4) species diversity and evenness indices were found to be relatively independent of physico-chemical factors, whereas species richness and the ratio of biomass to abundance were strongly correlated with water temperature and abundances of bacteria. It was concluded that planktonic protists are potentially useful bioindicators of water quality in a semi-enclosed mariculture system.

Morphology and morphogenesis of Apoholosticha sinica n. g., n. sp. (Ciliophora, Hypotrichia), with consideration of its systematic position among urostylids

This paper investigates the morphology, morphogenesis and SSU rRNA gene-based phylogeny of Apoholosticha sinica n. g., n. sp., isolated from mangrove wetland in Shenzhen, southern China. The new genus Apoholosticha is characterized by its bipartite adoral zone, clearly differentiated frontal cirri arranged in a bicorona, midventral complex composed of midventral pairs only, one marginal cirral row on each side, presence of frontoterminal and transverse cirri, and the lack of a buccal cirrus and caudal cirri. The type species, Apoholosticha sinica n. sp. is diagnosed by the elongated body shape and two kinds of cortical granules. Its main morphogenetic features are similar to that of Pseudokeronopsis except for (1) no buccal cirrus is formed and (2) its macronuclear nodules fuse into a single mass during cell division. Phylogenetic analyses for the new taxon indicate that Apoholosticha n. g. is most closely related to Nothoholosticha and Heterokeronopsis, and falls into the family Pseudokeronopsidae within the core Urostylida clade. In addition, a species that had been misidentified in previous literature is here recognized and assigned to the new genus as Apoholosticha sepetibensis (Wanick and Silva-Neto, 2004) n. comb. (basionym: Pseudokeronopsis sepetibensis Wanick and Silva-Neto, 2004).

Planktonic ciliate communities in a semi-enclosed bay of Yellow Sea, northern China: annual cycle

To reveal the annual patterns of planktonic ciliate communities, planktonic ciliate species composition, abundance and biomass, and responses to environmental conditions, were investigated during an annual cycle in Jiaozhou Bay, Qingdao, northern China. A total of 6 4 species belonging to five orders (Oligotrichida, Haptorida, Cyrtophorida, Hypotrichida and Tintinnida) were identified, 9 of which were dominant. Ciliate communities presented a clear seasonal pattern in terms of both abundance and biomass. A single peak of ciliate abundance and biomass occurred in late August, mainly due to the oligotrichids, tintinnids and haptorids. The 9 dominant species showed a distinct temporal distribution with seasonal successions of ciliate communities. Multivariate analyses revealed that ciliate abundance was significantly correlated with water temperature, dissolved oxygen and nutrients, especially nitrate nitrogen and soluble reactive phosphate (P < 0.05). These fin d ings provided basic data on annual cycle of planktonic ciliate communities in a semi-enclosed bay of Yellow Sea, northern China.

Functional groups of marine ciliated protozoa and their relationships to water quality

Ciliated protozoa (ciliates) play important ecological roles in coastal waters, especially regarding their interaction with environmental parameters. In order to increase our knowledge and understanding on the functional structure of ciliate communities and their relationships to environmental conditions in marine ecosystems, a 12-month study was carried out in a semi-enclosed bay in northern China. Samples were collected biweekly at five sampling stations with differing levels of pollution/eutrophication, giving a total of 120 samples. Thirteen functional groups of ciliates (A–M) were defined based on their specific spatio-temporal distribution and relationships to physico-chemical parameters. Six of these groups (H–M) were the primary contributors to the ciliate communities in the polluted/eutrophic areas, whereas the other seven groups (A–G) dominated the communities in less polluted areas. Six groups (A, D, G, H, I and K) dominated during the warm seasons (summer and autumn), with the other seven (B, C, E, F, J, L and M) dominating in the cold seasons (spring and winter). Of these, groups B (mainly aloricate ciliates), I (aloricate ciliates) and L (mainly loricate tintinnids) were the primary contributors to the communities. It was also shown that aloricate ciliates and tintinnids represented different roles in structuring and functioning of the communities. The results suggest that the ciliate communities may be constructed by several functional groups in response to the environmental conditions. Thus, we conclude that these functional groups might be potentially useful bioindicators for bioassessment and conservation in marine habitats.

Ontogenesis and Molecular Phylogeny of a New Marine Urostylid Ciliate, Anteholosticha petzi n. sp. (Ciliophora, Urostylida)

ABSTRACT. A new urostylid ciliate, Anteholosticha petzi n. sp., isolated from the northern China seas, was studied using live observation and protargol impregnation. It differs from all the congeners mainly in the highly flexible and variable body shape, its red‐brown to brick‐red colour, and the possession of three types of cortical granules. Analysis of morphometric and molecular data confirm the validity of A. petzi as a distinct species. Anteholosticha petzi n. sp. is characterized as follows: by having 3 frontal, 1 buccal, 2 frontoterminal, 2 pretransverse, and 8–11 transverse cirri; a midventral row that comprises 10–16 cirral pairs and extends ca. 60% of cell length; and 3 bipolar dorsal kineties. Ontogenesis is similar to that in Anteholosticha warreni except for the formation of the oral primordium and is characterized by: (1) the parental adoral membranelles are completely renewed and the oral primordium is formed de novo; and (2) the anlagen for the frontal–ventral–transverse cirri are formed as primary primordia. The small subunit rRNA gene sequence of A. petzi n. sp. was also compared with that of its congeners with the sequence differences ranging from 0.39% to 8.62%. Phylogenetic trees based on the SSU rRNA gene sequence were constructed, indicating the nonmonophyly of the genus Anteholosticha, as supported by the approximately unbiased test.

Morphology, morphogenesis and gene sequence of a freshwater ciliate, Pseudourostyla cristata (Ciliophora, Urostyloidea) from the ancient Lake Biwa, Japan.

The urostyloid freshwater ciliate Pseudourostyla cristata was recorded for the first time from Lake Biwa, a 4-million-year-old lake located in Shiga Prefecture, Japan. Its morphology and morphogenesis were investigated using live observation and protargol impregnation, and the SSU ribosomal RNA gene was sequenced. Based on the current observations and previous descriptions, this species is readily recognized mainly by the following characters: body slender or broadly oval to elliptical, and dark grey in color; size in vivo about 170-400 x 40-150 microm; pellicle flexible and contractile, with extrusomes forming a hyaline seam underneath; ciliature comprising about 60-130 adoral membranelles, usually 1 buccal cirrus, 20-24 frontal, 2 frontoterminal, 17-26 pairs of midventral, and 5-16 transverse cirri, 4-6 left and 4-5 right marginal rows, and 8-10 dorsal kineties; 15-83 macronuclear nodules and 2-9 micronuclei; freshwater habitat. The main morphogenetic developments are: (1) the oral primordium for the proter originates de novo on the dorsal wall of the buccal cavity, and the dedifferentiated undulating membranes and some parental proximal membranelles join in the primordial development; the old adoral zone will be partly replaced by new structures; (2) the oral primordium for the opisthe occurs epiapokinetally left of the midventral complex between the adoral zone and the transverse cirri; (3) the fronto-midventral transverse cirral (FVT) anlagen develop separately in both dividers by dedifferentiation of most of the midventral cirri; (4) the single buccal cirrus is generated from the posterior end of FVT anlage II; (5) the leftmost frontal cirrus is derived from the anterior end of the undulating membranes anlage (FVT anlage I); (6) the marginal rows of each side are formed from a single anlage which arises within the rightmost row; (7) the dorsal kineties develop by intrakinetal basal body proliferation; and (8) the most posterior FVT anlage contributes the two fronto-terminal cirri at its anterior end. The present observations indicate that P. cristata has a wide geographic distribution, and possesses constant morphological and morphogenetic traits. Phylogenetic trees inferred from SSU rRNA gene sequences suggest paraphyly of the genus Pseudourostyla.

A redescription of the marine hypotrichous ciliate, Nothoholosticha fasciola (Kahl, 1932) nov. gen., nov. comb. (Ciliophora: Urostylida) with brief notes on its cellular reorganization and SS rRNA gene sequence

The morphology and infraciliature of the marine hypotrichous ciliate Nothoholosticha fasciola (Kahl, 1932) nov. gen., nov. comb., isolated from mariculture waters near Qingdao, China, are redescribed based on live and protargol-impregnated specimens. Features reported for the first time include the possession of more than 50 macronuclear nodules and details of the infraciliature, i.e. 50-60 adoral membranelles, shortened paroral and endoral membranes, six frontal, one buccal and two to seven transverse cirri, ca. 40 pairs of midventral cirri, ca. 60-120 left and 70-120 right marginal cirri, three dorsal kineties, caudal and frontoterminal cirri absent. In addition, brief details of two stages of cellular reorganization in N. fasciola are supplied and comparisons with some related urostylids based on SS rRNA gene sequence data are reported. The new genus Nothoholosticha is established based primarily on the absence of frontoterminal cirri, which distinctly separates it from similar urostylid genera. Anteholosticha longissima is transferred to Nothoholosticha as N. longissima (Dragesco and Dragesco-Kernéis, 1986) nov. comb. and Holosticha antarctica is transferred to Pseudokeronopsis as P. antarctica (Wilbert and Song, 2008) nov. comb.

Ontogeny and molecular phylogeny of a new marine ciliate genus, Heterokeronopsis g. n. (Protozoa, Ciliophora, Hypotricha), with description of a new species

The morphology and morphogenesis of a new ciliate, Heterokeronopsis pulchra g. n., sp. n., isolated from a mangrove wetland near Shenzhen, southern China, were investigated using live observation and protargol impregnation methods. Heterokeronopsis g. n. is characterized by having a bipartite adoral zone, an extremely shortened paroral membrane, frontal cirri arranged in an indistinct bicorona, a midventral complex composed of midventral pairs and midventral row(s), one left and one right marginal row, bipolar dorsal kineties, and buccal cirri; frontoterminal, transverse, and caudal cirri are absent. The single species H. pulchra sp. n. has a long, slender body that is brownish in colour, two kinds of cortical granules, one posteriorly located contractile vacuole, one buccal cirrus, usually six frontal cirri, three dorsal kineties, and one midventral row. The main morphogenetic features are: (i) the old oral apparatus is completely replaced by new structures derived from the oral primordium of the proter which originates de novo on the dorsal wall of the buccal cavity, (ii) the posteriormost frontal-midventral-transverse cirral anlage generates a midventral row, (iii) no frontoterminal and transverse cirri are formed, (iv) the anlagen for the marginal rows and the dorsal kineties are formed intrakinetally, and (v) the macronuclear nodules fuse into a mass at the middle stage. Phylogenetic analyses based on SSU rRNA gene sequence data reveal that Heterokeronopsis pulchra is a member of the family Pseudokeronopsidae and is most closely related to Nothoholosticha fasciola.

Morphological description of three marine ciliates (Ciliophora, Scuticociliatia), with establishment of a new genus and two new species

Three marine scuticociliates, Falcicyclidium fangi nov. gen., nov. spec., Falcicyclidium atractodes nov. spec., and Cristigera media Kahl, 1928 were investigated using live observation and silver impregnation methods. The genus Falcicyclidium is distinguished by the combination of: (i) dorsoventrally flattened body, (ii) hook-like (falciform) paroral membrane, (iii) anterior end of paroral membrane posterior to anterior end of membranelle 1, and (iv) multiple caudal cilia. Falcicyclidium fangi nov. spec., the type of the new genus, can be recognized by the combination of its large size, extremely dorsoventrally flattened (3:1) body, consistently 10 somatic kineties, and the broad, elongate buccal area occupying 60% of the body length. Falcicyclidium atractodes nov. spec. is mainly characterized by a unique spine projecting from both the anterior and posterior end. The uncommon form, Cristigera media is redescribed based on the population from Qingdao, the statistic data and additional features, especially the morphology of the living cells, are documented.