Spatial And Temporal Patterns Of Planktonic Ciliate Communities And Relationships To Environmental Conditions In Jiaozhou Bay, Northern China

Planktonic ciliates are important components of microplankton communities and play acrucial role in the functioning of microbial food webs. In order to provide original and basic dataon understanding planktonic ciliate community dynamics and their relationships withenvironmental conditions, bioassessment of water quality, functional groups and energytransferring process in microbial food web, a survey on planktonic ciliates was carried out duringan annual cycle in semi-enclosed Jiaozhou bay, Qingdao, northern China.The following conclusions could be drawed:1) Environmental variables of the five sampling sites over the12-month period showing thatthe concentrations of water temperature, salinity, pH, dissolved oxygen (DO) and chlorophyll-a(Chl a) were consistent with records and had minor differences at all five sites. Concentrations ofnutrients ammonium nitrogen (NH4-N), nitrate nitrogen (NO3-N), nitrite nitrogen (NO2-N) andsoluble reactive phosphate (SRP) were generally highest at sites B, C and D and lowest at sites Eand A.2) To reveal the annual patterns of planktonic ciliate communities, planktonic ciliate speciescomposition, abundance and biomass, and responses to environmental conditions wereinvestigated. A total of64species belonging to five orders (Oligotrichida, Haptorida,Cyrtophorida, Hypotrichida, and Tintinnida) were identified,9of which were dominant. Ciliatecommunities presented a clear seasonal pattern in terms of both abundance and biomass. A singlepeak of ciliate abundance and biomass occurred in late August, mainly due to the oligotrichids,tintinnids and haptorids. The9dominant species showed a distinct temporal distribution withseasonal successions of ciliate communities. Multivariate analyses revealed that ciliateabundance was significantly correlated with water temperature, dissolved oxygen (DO) andnutrients, especially nitrate nitrogen and soluble reactive phosphate (P <0.05). These findingsprovided basic data on annual cycle of planktonic ciliate communities in a semi-enclosed bay ofYellow Sea, northern China.3) Spatial patterns of planktonic ciliate communities for assessment of marine environmental status were studied based on our data. Multivariate/univariate analyses demonstrated that:(1) theplanktonic ciliate community structures represented significant differences among the five sites;(2) spatial patterns of the ciliate communities were significantly correlated with environmentalvariables, 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 nitrogenand/or SRP; and (4) both species richness and species diversity indices were correlated withNO3-N and salinity. These results suggest that planktonic ciliated protozoa might be used as arobust bioindicator of marine water quality.4) The spatial taxonomic patterns and diversity measures in response to physical-chemicalvariables were studied based on our data. The taxonomic distinctness (Δ*) and the averagetaxonomic distinctness (Δ+) were significantly negatively correlated with the changes ofnutrients (e.g., nitrate nitrogen and soluble active phosphate)(P <0.05). Pairwise indices of Δ+and the variation in taxonomic distinctness (Λ+) showed a decreasing trend of departure from theexpected taxonomic breadth in response to the eutrophication stress and anthropogenic impact.The taxonomic relatedness (especially the pairwise Δ+and Λ+) indices of ciliate communities arerobust as an indicator with scientifically operational value in marine environmental assessment.5) The annual and spatial patterns of body-size spectra of planktonic ciliate communities andtheir relationships to environmental conditions were studied based on dataset. The body sizes ofthe ciliates, expressed as equivalent spherical diameters (ESD), may be classified into five ranks:S1(5–35μm), S2(35–55μm), S3(55–75μm), S4(75–100μm) and S5(100–350μm). Thesebody-size ranks showed a clear temporal succession of dominance in the order of S2(January–April)â†'S1(May–July)â†'S4(August–September)â†'S3(October–December). Thetemporal variations in their body-size patterns were significantly correlated with changes inenvironmental conditions, especially water temperature, salinity, dissolved oxygen concentration(DO) and nutrients. In terms of abundance, rank S2was significantly correlated with watertemperature, DO and nutrients, whereas ranks S4and S5were correlated with the salinity andnutrients respectively (P <0.05). The spatial body-size patterns of ciliated zooplanktonrepresented significant differences among the five sites, and were significantly correlated withthe changes of physico-chemical parameters, especially salinity, dissolved oxygen and nutrients.Two paired indices, the average body-size distinctness (AvBSD) and the variation in body-sizedistinctness (VarBSD), were proposed based on the trait resemblances among ciliate species inbody-size pattern. The paired measures showed a clear decreasing trend of departure from theexpected body-size spectra in response to water quality status. These results suggest that thebody-size pattern of ciliated zooplankton showed a clear seasonal cycle and significantlyassociated with environmental conditions in marine ecosystems might be used as a potentialindicator of marine water quality.6) In order increase our knowledge and understanding of the functional structure of ciliate communities, and their relationships to environmental conditions in marine ecosystems. Thirteenfunctional groups of ciliates (A-M) were defined based on their specific spatiotemporaldistribution and relationships to physicochemical parameters. Six of these groups (H-M) werethe primary contributors to the ciliate communities in the polluted/eutrophic areas, whereas theother seven groups (A-G) dominated the communities in less polluted areas. Seven groups (A, D,G, H, I and K) dominated during the warm seasons (summer and autumn) with the other six (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 species) and L (mainly loricate tintinnids) were theprimary contributors to the communities. It was also shown that aloricate ciliates and tintinnidsrepresented different roles in structuring and functioning of the microbial loop. The resultssuggest that the ciliate communities may be constructed by several functional groups in responseto the environmental conditions. Thus, we conclude that these functional groups might bepotentially useful bioindicators for bioassessment and conservation in marine habitats.7) To analyze distribution patterns and the interspecies interactions between planktonicciliated protozoa and microalgae in marine ecosystems, the dataset of microplanktoncommunities were investigated using a range of multivariate methods. A total of164microplankton species comprising100microalagae and64ciliates were identified from120samples, respectively. Both planktonic microalga and ciliate assemblages showed clear seasonalpatterns and significantly correlated between their temporal variations in abundance. Themicroplankton communities were characterised by14ciliates (e.g., Strombidium sulcatum,Tintinnopsis tubulosoides and Strombidium cheshiri) and18microalgae (e.g., Skeletonemacostatum and Alexandrium tamarense). Multiple regression analyses showed that the interspeciesinteractions among these dominant species represented a complex network with a clear seasonalshift. The results suggest that there is a complex network with a seasonal shift in themicroplankton communities, and that multivariate statistical approaches were a useful tool toreveal the species distribution patterns and interspecies interactions among microplanktons inmarine ecosystems.8) The contribution of non-loricate ciliate assemblage to ecological pattern of ciliatedprotozoan community was studied based our dataset. Results showed that:(1) the non-loricateciliate assemblages were the primary components and significantly correlated with the totalciliate communities in terms of species number, abundance and biomass;(2) the ecologicalpattern of non-loricate ciliate assemblages was significantly related to that of both total ciliatecommunities and variations in environmental variables;(3) spatiotemporal variations inbiodiversity (richness, diversity and evenness of species) indices of non-loricate ciliateassemblages were significantly correlated with those of total ciliate and the environmentalconditions, especially nutrients NO3-N, NO2-N and SRP. These results suggest that thenon-loricate ciliates are a primary contributor to ecological pattern of total ciliate communitiesand might be used as a potential bioindicator for bioassessment in marine ecosystems. 9) Congruency using non-loricate ciliates as a surrogate to analyze taxonomic distinctnesspattern of ciliated protozoan communities for assessing water quality was studied.Multi/univariate analyses showed that:(1) with significant consistency with the total ciliatecommunities, the spatial pattern of non-loricate ciliates was significantly correlated with thechanges of environmental status;(2) four taxonomic relatedness measures were significantlycorrelated with those of the total ciliate communities;(3) spatial variations in four taxonomicdiversity indices of non-loricate ciliates were significantly related with the changes ofenvironmental variables, especially nutrients;(4) the paired taxonomic biodiversity indices (Δ+and Λ+) of non-loricate ciliates showed a clear decreasing trend of departure from the expectedtaxonomic breadth in response to water quality. These results suggest that non-loricate ciliateassemblages can be used as a potential surrogate of ciliate communities when assessing marinewater quality using taxonomic distinctness measures, especially the paired indices based onpresence/absence data.