Changes In Ecological Characteristics Research Articles

Influence of a biofilm bioreactor on water quality and microbial communities in a hypereutrophic urban river

ABSTRACT Biofilms play an important role in degradation, transformation and assimilation of anthropogenic pollutants in aquatic ecosystems. In this study, we assembled a tubular bioreactor containing a biofilm substrate and aeration device, which was introduced into mesocosms to explore the effects of bioreactor on physicochemical and microbial characteristics of a hypereutrophic urban river. The biofilm bioreactor greatly improved water quality, especially by decreasing dissolved inorganic nitrogen (DIN) concentrations, suggesting that biofilms were the major sites of nitrification and denitrification with an oxygen concentration gradient. The biofilm bioreactor increased the abundance of planktonic bacteria, whereas diversity of the planktonic microbial community decreased. Sequencing revealed that Proteobacteria, Bacteroidetes, Planctomycetes, and Actinobacteria were the four predominant phyla in the planktonic microbial community, and the presence of the biofilm bioreactor increased the relative abundance of Proteobacteria. Variations in microbial communities were most strongly affected by the presence of the biofilm bioreactor, as indicated by principal component analysis (PCA) and redundancy analysis (RDA). This study provides valuable insights into changes in ecological characteristics associated with self-purification processes in hypereutrophic urban rivers, and may be of important for the application of biofilm bioreactor in natural urban river.

Age, growth, mortality and population structure of silver croaker Pennahia argentata (Houttuyn, 1782) and red bigeye Priacanthus macracanthus Cuvier, 1829 in the north-central Taiwan Strait

Summary The main objectives of this study were to estimate the age, growth, mortality and population structure of silver croaker Pennahia argentata (Houttuyn, 1782) and red bigeye Priacanthus macracanthus Cuvier, 1829 and to explore the factors causing the fluctuation of the fish populations and the ecological parameters. The two species were randomly sampled, with 80~120 individuals of each species captured every month from a single trawler fishery (mesh size 250 mm), March to November 2006, in the north-central Taiwan Strait. A total of 994 speciments of silver croaker and 851 speciments of red bigeye were collected. Compared with previous studies, the mean length and weight, mean age, the minimum size at first sexual maturity, the asymptotic length (L∞) and weight (W∞) of the two species has decreased in recent decades, indicating that the populations were younger, smaller and earlier in sexual maturity. Meanwhile, the growth coefficient (K) increased, the mortality coefficients (Z, F, M) were higher, and the exploitation rate (E) indicated overfishing. Fishing is a key driving force that can cause abundant fluctuations and changes in ecological characteristics in these two demersal fishes in this area. Accordingly, the traditional fishery management approach, such as the reduction in fishing effort, coupled with the Ecosystem-based Fishery Management (EBFM) should be implemented to achieve sustainable demersal fisheries.

불광천 자연형 하천 정비구간의 생태적 특성 변화 비교 연구

본 연구는 2002년 완공된 불광천(佛光川)자연형 하천 정비구간 생태적 특성변화를 비교하여 향후 하천관리의 기초자료 제공을 목적으로 불광천 자연형 정비사업에 대한 문헌연구, 정비사업 전 후와 현재의 물리적 환경변화 조사 분석과 생태계변화 분석을 주요내용으로 하였다. 준공 이후 호안에 적용된 공법을 중심으로 훼손현황을 분석한 결과, 수충부(水衝部)지역, 강우시 유출수가 발생하는 지점을 중심으로 호안이 유실되고 식생이 훼손되었다. 현존식생 분야에서는 식물도입 내용과 현존식생을 비교 분석한 결과, 저수로변에 파종한 혼합종자 중 싸리류, 벌개미취 등은 대부분 유실되어 큰김의털이 크게 우점하였고, 갈대, 물억새, 갯버들은 소규모로 식재되어 대부분 유실되었다. 지형구조 및 초본식생구조를 종합한 결과, 혼합종자를 파종한 지역은 크게 두 가지 식생유형으로 변화하였는데, 부유물질이 많은 하천 퇴적지에서 주로 생육하는 개여뀌, 소리쟁이 등이 우점하는 지역과 건조지성 벼과식물인 큰김의털, 개밀 등이 우점하는 지역으로 구분되었다. 저수로 호안부에 갈대 및 갯버들을 식재한 공법 적용지는 저수로폭 축소와 함께 유실되었으며, 저수부에 일부 갈대, 물억새, 갯버들이 소규모 군락을 형성하고 있었으나 그 세력이 미미하였고, 식물종 구성이 매우 단순해진 상태였다. 이에 불광천 자연형 정비구간의 관리방안을 제안하였다. 첫째, 도시하천 치수기능을 고려하되 유수 흐름을 모니터링하여 적절한 호안공법을 적용해야 하며, 둘째, 하천환경에 적합한 목표식생군락(目標植生群落)을 설정하고, 고밀도로 꾸준히 식재해야 한다. 이때 현재와 같이 관상용 자생식물 보식은 지양해야 하며,교란식생은 지속적 제거가 필요하였다. The aim of this study was to provide basic data in managing the project that was carried out on Bulgwangcheon in a nature-friendly way to improve the conditions around the areas, which was brought to completion in 2002, based on changes in ecological characteristics. For this propose, this study examined documents related to the project, compared physical and enviromnental changes before and after the project was conducted and analyzed changes in the stream ecosystem. The result showed that in areas that effluent water was often observed, especially when it rained, the river wall was washed away and vegetation was found damaged. As for actual vegetation, this study compared planting coverage of each section of the research area and actual vegetation charts. The results indicated that Lespedeza spp., Aster koraiensis among mixed seeds that were planted in the reservoir path were almost swept away while Festuca arundinacea dominated the areas. Phragmites communis, Miscanthus sacchariflorns and Salix gracilistyla which had been planted in a small number were also almost washed out though a small number of them were left to form a colony. After examining the topography and structure of the plant community, this study found that areas where mixed seed were planted had changed into two types of vegetation: First type of area is dominated by P and R which are usually raised in apron with abundant floating particles. The second type of area is dominated by dry gramineous plant such as F and A. Areas around low flow channel where Phragmites communis, Miscanthus sacchariflorus and Salix gracilistyla planting construction method is applied was washed away with the width of low flow channel reduced. Though P, M and S formed a small community in some areas around the low flow area, they were in small number and in composition of simple plant species. Two ways were suggested in this study to manage the stream in an ecological way. First, adequate revetment construction methods should be applied by monitoring the flow of the stream as well as considering the flood control of urban streams. Second, target vegetation communities that are suitable for the environment of the stream should be chosen and be plantedconstantly with high density. At the same time, ornamental native plants shouldn't be planted as they have been and disturbing vegetation should be removed.

VECTOR BORNE TRANSMISSIBLE ZOONOSES IN MONTENEGRO

SUMMARY Vector borne transmissible zoonoses are becoming more and more important in the group of emerging and reemerging infections. We present the characteristics and actuality of this group of infectious diseases in Montenegro for the period 1998 - 2011. In examinations, standard epidemiological, clinical, serological, pathohistological diagnostic methods are employed. Natural conditions in Montenegro make it an important endemic area for more vector borne transmissible zoonoses. The changes of ecological characteristics, the vectors and infective agents, present the accidence for expansion and increasing importance of these infections in national pathology. According to the fact that it is an international port of nautical, continental and air traffic, Montenegro has responsibility for control and management of diseases belonging to the group of the travel and tropical diseases.

Studies on ecological characteristics variation and population dynamics of four lizardfishes in the southern Taiwan Straits

The ecological characteristics of four lizardfishes, Trachinocephalus myops, Saurida undosquamis, Saurida tumbil and Saurida elongata, were studied from specimens (910 T. myops, 454 S. undosquamis, 686 S. tumbil and 744 S. elongata) collected monthly in the southern Taiwan Straits from April 2005 to March 2006. The population dynamics of the four lizardfishes was also discussed by the comparison with the previous studies. All being composed of 7 a classes; the dominant group of T. myops and S. tumbil was 1–2 a, while S. undosquamis and S. elongate were 2–3 a. The total mortality coefficient Z and the fishing mortality F were at high as indicated by the exploitation ratio E(>0.5), and a large number of by-caught juvenile and young fishes showing that the stock of lizardfishes in this area was overexploited and the fishing gear was irrational. Compared with the previous studies, the maximum and mean fork length, body mass and age of the four lizardfishes declined gradually, the lizardfishes populations were younger in age and smaller in size. The asymptotic fork length L∞ decreased while increasing growth coefficient k, and age at the inflexion point of mass tr was younger compared with the previous studies. The declining of older ones has moderated the feeding competition and the younger ones grew faster. The larger mortality parameters Z,M and F have revealed higher fishing pressure. The smaller change of the first mature fork length of female T. myops and the change from K selection pattern to r selection pattern of S. tumbil have indicated a more vulnerable fishery ecosystem in this area. The changes of ecological characteristics and population dynamics may be caused by over-exploitation of demersal fishes such as the lizardfishes, especially a large number of juvenile and young fishes by-catch by the current fishing gears and methods. Therefore, in addition to the traditional fishery management approach such as the minimum length-limit, ecosystem approach to fisheries management (EAF) should be taken to improve the practical marine ecosystem management, including increased fishing intensity of the non-economic species especially the feeding competitors of the lizardfishes and the conservation of the pelagic fishery population in the fisheries ecosystem, in order to restore the fishery population and achieve the sustainable use of the fishery stocks.

Erratum: Incorporating lakes within the river discontinuum: longitudinal changes in ecological characteristics in stream–lake networks

Erratum: Incorporating lakes within the river discontinuum: longitudinal changes in ecological characteristics in stream–lake networks

Incorporating lakes within the river discontinuum: longitudinal changes in ecological characteristics in stream–lake networks

Lakes and rivers are intimately connected in an alternating series of lentic and lotic reaches in many regions. The study of lakes and their outlets in hierarchical and branching river networks has not gained the attention of stream ecologists, and little effort has been focused on synthesizing the ecology of lake–stream interactions within a drainage network. Rapid and predictable changes in the ecological characteristics of streams occur at the interface with lakes. The influence that a lake might have on a stream is dependent on its position within the stream, stream type and size, lake size and shape, and the inlet and outlet positions. Little is known about the influences of multiple lakes within stream–lake networks and how these influences are determined by network shape and pattern. Fruitful collaborations and novel insights will come from the combined efforts of limnologists, stream ecologists, and landscape ecologists. Geographic information systems and network analyses will play an important role in summarizing aquatic landscape characteristics and creating a predictive science of aquatic networks. Lakes need to be more explicitly incorporated into ecological concepts in stream ecology, and reciprocally, streams need to be incorporated into ecological concepts involving lakes for the successful management and conservation of our aquatic resources.

Biomonitoring of benthic Chironomidae (Diptera) fauna of two Amazonian 'igarapés' influenced by the activities of a bauxite mine

The biomonitoring of Chironomidae (Diptera, Insecta) benthic larvae on igarapes Saraca and Carana (1°25' and 1°35' S and 56°15' and 56°25' W) was done foccusing changes of ecological characteristics resulting from the activities of a bauxite mine in Central Amazonia. The result s showed highest taxoriornic richeness and abundances on sections damed by the construction of a railroad and Chironomus spp., Goehlichironomus spp. and Polvpedilum spp. predominated on those areas.

Seasonal changes of ecological characteristics on culms and leaves of Pleioblastus pubescens Nakai growing under different light conditions

ケネザサを異なる光条件で地下茎から生育させ，稈数と葉数の季節変化，褐変度，および葉の形態を調べた。稈の発生と生残では，分げつ稈を含めれば明るい処理区のほうが，稈の発生期間が長く，積算発生数が多い傾向があった。稈の枯死数は，1％ 区で特に多かった。明るい処理区ほど伸長終了時期の稈の生残数が多い傾向がみられた。稈の伸長成長では，明るい処理区ほど伸長速度が遅く，伸長終了後の稈の長さが短い傾向があった。したがって，明るい環境では稈の数を増やし水平方向に広がるように，暗い環境では稈のサイズを大きくして垂直方向に伸びるように成長し，それぞれ異なる侵入と優占の仕方で群落を発達させると考えられる。葉群動態では，明るい処理区ほど葉が早く褐変し，落葉が早かった。明るい処理区では，葉の寿命は短いが，稈の発生期間が長いために，葉の展葉期間が長いことによって葉群を維持し，暗い処理区では，葉の展葉期間は短いが，葉の寿命が長いことによって葉群を維持することが示唆された。葉の形態からは，明るい処理区ほど葉面積が小さく厚い陽葉的な葉をつけると考えられた。