Wyniki wyszukiwania - Biblioteka Nauki

1

Phytoplankton Community Stability as a Health Indicator of Whiteleg Shrimp in an Intensive Pond

100%

Musa M. , Mahmudi M. , Lusiana E. D. , Buwono N. R. , Arsad S.

Ecological Engineering & Environmental Technology

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2024

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tom Vol. 25, iss. 1

332--340

EN

The goal of this study was to examine and assess the stability of phytoplankton communities in connection to the different health status type of shrimp pond (healthy and diseased) in an intensive culture. The research was conducted in two ponds located in Probolinggo region, which had different health status until the eight week of harvest period. Several water quality variables and phytoplankton community composition were observed. Non-metric dimensional scaling and analysis of similarity were used to compare the phytoplankton community structure and water quality parameters in both ponds. In addition, the stability of phytoplankton community in these ponds was measured using species turnover rate, rate change of composition community, and community stability indices. The results showed that phytoplankton community structure and water quality factors between a diseased and healthy pond were not statistically significant. On the other hand, the phytoplankton community in the healthy pond was more stable than that of the diseased pond. Furthermore, ammonia and phosphate were found as the dominant factors affecting the phytoplankton community in the studied ponds.

2

The small-scale species mobility in calcareous grasslands - example from Southern Poland

86%

Baba W.

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nr 1

EN

In this paper I use the different measures of species mobility to describe the fine small-scale dynamics of calcareous grassland built mainly by perennial species and developed in the highly heterogeneous habitat of calcareous rocks. The community showed the low dynamics on a plot-scale (100 m2) and a high one on the scale of 1 m2. However, the studied species differed greatly in calculated indices: turnover rate, (T; 6-64), residence time (RT; 0.5-21.8 y) and carousel time (CT; 4-420 y) as well as the observed tendency to persistence on the spots (PERSIST) and their re-colonisation (AGAIN). This allowed to distinguish the three groups of species: (1) "core species" characterized by high frequency and low T and high CT and RT values, which determine the low dynamics of a community on the plot scale, (2) species with intermediate mobility rate and (3) the group with high mobility rate. The observed cumulative frequencies of all the studied species (CFobs) were much lower than expected under the random re-assignation model (CFRR). Moreover, they were also lower than those predicted by random immigration model (CFRI). The results showed that the "complex carousel" model rather than "single carousel" one explained better the small-scale dynamics of calcareous grasslands.

3

Soil fauna community dynamics during soil thawing period in the subalpine and Alpine forests of Western China

72%

Tan B. , Wu F. , Yang W. , Wang A. , Yang Y.

Polish Journal of Ecology

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2012

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tom 60

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nr 4

EN

The frequently changed temperature could have great effects on soil fauna community during soil thawing period in cold areas. Therefore, soil faunas were investigated in both the soil organic layer (OL) and mineral soil layer (ML) in the primary fir (Abies faxoniana) forest (PF), fir and birch (Betula albosinensis) mixed forest (MF) and secondary fir forest (SF) in the eastern Qinghai–Tibet Plateau every ten days between March 5 and April 25, 2009. Soil macrofauna was picked up by hand in the fields. Mesofauna was collected and separated from the soil samples by Baermann and Tullgren methods, respectively. The dominated species of macrofauna belongedto Coleoptera and Diptera at the early stage of soil thawing, and to Coleoptera, Diptera, Araneae and Hymenoptera at the later stage. However, the dominated species of mesofauna belonged to Nematode, Collembola, and Acari in the whole soil thawing. The density, number of taxa, and diversity index of soil fauna showed significant change with temperature fluctuations and reached an obvious peak when soil temperatures rising above 0°C. The density and number of taxa of macrofauna in both the OL and ML were the lowest on March 5 in the three forests, but the density of mesofauna in both the OL and ML was the highest on March 25, except for the ML in the PF. These results implied that soil fauna community was sensitive to temperature fluctuations, which is important in understanding the ecological processes in the winter–spring transitional period.

4

Relationship between nematode community and biomass and composition of periphyton developing on artificial substrates in floodplain lake

58%

Vidakovic J. , Palijan G. , Cerba D.

Polish Journal of Ecology

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2011

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tom 59

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nr 3

EN

Periphyton colonisation on artificial substrate (microscopic glass slides) was investigated from July to November 2007, in Lake Sakadaš (Danube River floodplain Kopački rit, Croatia). Two different stations were chosen due to different post – flood conditions. The aim of the study was to follow temporal changes of nematode community composition and trophic structure in relation to periphyton biomass and bacterial abundance. In bryozoan – dominated periphyton (Plumatella emarginata Allman, 1844) nematodes were represented by 86 and 87% of total associated invertebrate fauna at S1 and S2 respectively. Total nematode abundance (up to 600 ind. 10 cm-2 at one station and up to 1130 ind. 10 cm-2 at another station) correlated significantly with the abundance (meaured as CFUs – colony forming units) of copiotrophic and oligotrophic bacteria at one station (r = 0.963, 0.998, P <0.05) and with organic and inorganic content of periphyton at another station (r = 0.891, 0.899, P <0.05). Nematode trophic groups (epistrate feeders, chewers, detritus feeders and suction feeders) were equally developed at both stations except detritus feeders whose species richness and abundance were significantly higher at the S1. Epistrate feeders were the most abundant trophic group in nematode assemblages at both stations with Chromadorina bioculata being the dominant species. Change in dominance of epistrate feeders by chewers (Brevitobrilus stefanskii) and suction feeders (Crocodorylaimus sp.) coincided with the occurrence of flood pulse. Effect of flood pulse on nematode community structure was probably indirect, alterating concentration of dissolved oxygen which chromadorids are sensitive to. The structure of nematode community developed through time differs between investigated stations indicating high sensitivity to bacterial abundance, periphyton biomass and P. emarginata mats which made the habitat more diverse and patchy.

5

Soil seed bank and extant vegetation of a dry valley

58%

Li Y. , Bao W. , Wu N.

Polish Journal of Ecology

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2011

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tom 59

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nr 3

EN

Although crucial for guiding vegetation improvement efforts, soil seed bank (SSB) and extant vegetation (EV) in dry valleys remains poorly understood. A germination method and field surveys were applied to address this problem and investigate the characteristics of SSB and corresponding EV of eight sites across the dry Minjiang River valley in Southwest China. Furthermore, the relationships between SSB and EV were compared to provide guidance for vegetation enhancement. Eight sites were classified into two groups – central and transitional sites that differ according to moisture conditions. Seed density and species richness in SSB were lower in less moist central sites compared with those in more moist transitional sites of the valley as well as the coverage of the community. Moreover, species richness and litter thickness were lower in central sites. Comparing SSB strategies of species from eight sites, transient strategy was the most frequently observed category, followed by short-term persistent and long-term persistent strategies. In terms of both SSB and EV, the most abundant life forms were hemicryptophytes, intermediate phanerophytes, and therophytes, whereas less abundant were chamaephytes and cryptophytes. Low Sorenson’s similarity indices (22–32%) and significantly negative Kendall’s correlation in species composition indicate that species composition of SSB was not closely related to corresponding EV for each of the eight sites. Low seed density, especially the lack of viable dominant shrub seeds, dominant transient SSB strategy species, and low correspondence in species composition between SSB and EV imply that the potential for vegetation enhancement in the dry valley is weak, particularly in less moist central sites. To preserve the good EV of more moist transitional sites and introduce seeds of dominant species to improve poor EV in central sites, EV is likely to be a feasible standard for improving vegetation in dry valleys.