Effects of natural forest conversion and plantation tree species composition on soil macrofauna communities in Northeast China mountains

As primary and secondary forests are being replaced by plantations across the globe,the soil macrofauna community structure is also affected,but little is known about the impact of mixed culture plantations compared with monocultures on the soil macrofauna.To determine the impact of forest conversion on soil macrofauna,we surveyed the soil macrofauna in two broad-leaved and three coniferous monoculture stands and four coniferous-broadleaved mixed stands,and in adjacent reserved secondary stands as a reference.Soil macro fauna community composition was significant affected by forest type,season and their interaction(P<0.05).The abundance,taxa richness and diversity of soil macro fauna changed to different degrees depending on the plantation type.Broadleaved monoculture stands and secondary stands had similar macrofauna abundance and taxa richness,but values were lower in coniferous stands than in secondary stands.The Shannon index for macrofauna in coniferous stands was also the lowest,but the Pielou index did not differ between forest types.The negative effects of the conifer monoculture on soil macro fauna were not present in the mixed stands with broad-leaved trees.Forest conversion impacted soil properties;soil moisture,NO_(3)^(-),and pH were significant drivers of soil macrofauna community structure.The impact of forest conversion on soil macrofauna was closely dependent on tree species composition and diversity.The macro fauna community structure in the broadleaved and the mixed stands were relatively similar to that in the natural forest,and thus recommended for forest conversion in the study area.

Species composition and influencing factors of understory woody species in Robinia pseudoacacia plantations on the Loess Plateau

Black locust(Robinia pseudoacacia L.)plantations have contributed significantly to soil and water conservation and ecological reconstruction on China’s Loess Plateau.Understanding the impact of stand and environment on species composition of understory woody plants will improve the stability of existing black locust plantations.Ten stands were selected in second-generation black locust plantations in tableland and gully areas of the Loess Plateau.The number of understory tree species in the tablelands was significantly lower than in the gully stands.Regenerated black locust(19.76%)and Rubus corchorifolius L.f.(64.85%)were the most abundant understory tree and shrub species,respectively,in the tableland stands;Broussonetia papyrifera(L.)L’Hér.ex Vent.(6.77%)and Acanthopanax senticosus(Rupr.Maxim.)Harms.(37.22%)were most abundant in the gully stands.Species richness(S),Shannon diversity(H),and evenness index(J)of the understory plants were significantly lower in the tableland stands than in the gully stands.More diverse understory species and community structures occurred in the gully stands.Differences in species diversity among landform positions may be attributed to differences in soil moisture.In addition,77.57%of the variation in understory species composition was explained,among which shrub and herb coverage,stand age,leaf area index,slope and total soil phosphorus in the 10-20 cm layer were the main factors.Soil organic carbon and total potassium significantly impacted S,H and J.Considering the environmental conditions and the biological characteristics of the plants investigated,R.corchorifolius should be given priority in the development of tableland stands,while B.papyrifera and Celtis sinensis Pers.should form mixed forests with black locust in gully stands.This management could promote biodiversity and stability of the existing black locust plantations but also optimize regional landscape patterns.

Species Composition and Diversity of Fagus longipetiolata in Leigong Mountain, Guizhou Province

[Objectives]To understand the species composition and diversity of Fagus longipetiolata community.[Methods]The F.longipetiolata community in Guizhou Province was investigated by typical plot method.[Results]There were 107 species of vascular plants belonging to 79 genera and 51 families in Leigong Mountain F.longipetiolata community,including 3 species of pteridophytes belonging to 3 genera and 3 families,104 species of spermatophytes belonging to 76 genera and 48 families,including 3 species of gymnosperms belonging to 3 genera and 3 families,and 101 species of angiosperms belonging to 73 genera and 45 families.The types of Leigong Mountain F.longipetiolata community were divided into 7 formations,and the top 10 important species of each formation were Fagaceae,followed by Lauraceae and Ericaceae.The change trend of tree layer richness index was formation I>formation IV>formation VI>formation III>formation VII>formation II>formation V;the dominance index was formation I>formation IV>formation V>formation VI>formation VII>formation III>formation II;H diversity index was formation V>formation II>formation I>formation III>formation VII>formation VI>formation IV;the evenness index is formation II>formation III>formation VI>formation VII>formation IV>formation I>formation V;the total diversity index of the community,formation I(3.67)was the highest,formation V(2.74)was the lowest,manifested as formation I>formation III>formation VI>formation II>formation IV>formation VII>formation V.[Conclusions]The community stability is closely related to its species composition,and the background species is the basis for the survival of the community;the existence of rare species can further enhance the community diversity index and enhance the community stability.

Species composition and diversity of Euphausiacea in the East China Sea

Based on the data of four seasonal oceanographic censuses in the East China Sea （23°30＇-33°00＇N, 118°30＇-128°00＇E） in 1997-2000, the species composition and the diversity of Euphausiacea were discussed as well as their relations with environmental variables. Results showed that there were totally 23 different species of Euphausiacea, in which 16 occurred in spring and autumn respectively; 15 were present in summer and only 10 were observed in winter. According to the calculated alternation fraction （R）, the species composition showed a clear seasonal alternation with the changes of seasons. Moreover, the environmental variables had different impacts on the distribution of Euphausiacea in different seasons. The distribution in summer was not significantly related to water temperature and salinity. However, the surface salinity was a major determinant of the distribution in spring. In autumn, both surface and bottom temperatures were influencing factors. The distribution in winter depended on salinity at the surface and 10 m depth as well as the temperature at 10 m depth. Regarding to the seasonal variation of species composition, the variations in spring, summer and autumn were not so significant as those in winter. Except in summer, the species number changed with synchronous water temperature and salinity, as a result of the presence of warm currents in the East China Sea and the habitability of the dominant species. Since Euphausiacea tend to agglomerate, the distribution of different species was uneven, which was the major reason for the low diversity of Euphausiacea in the East China Sea.

Studies on the species composition and biodiversity of free-living marine nematodes in the southern Huanghai Sea

Free-living marine nematodes were sampled and studied at a grid of 22 stations （from 32°29.35′ to 37°0.56′N, 122°0.37′ to 125°1.16′ E） in the southern Huanghai Sea in January 2003. Nematode abundance varied from 50.5 to 127.2 ind./cm^2 [（83.1 ±24.7） ind./cm^2] at different stations, 80.1% of the total nematodes were in the surface layer （0-2 cm） of sediments. Two hundred and twenty-three species or taxa of marine nematodes belonging to 145 genera, 32 families and four orders were identified and first recorded in the Huanghai Sea. The common dominant species were Dorylaimopsis rabalaisi, Terschellingia longicaudata, Sphaerolaimus bolticus, Metalinhomoeus longiseta, Quadricoma scanica, Prochromadorella sp., Paramonohystera riemanni, Marylynnia sp. 1, Vasostoma spircaum, Halalaimus spp., Pierrickia sp. 1 and Promonhystera faber. Nematode diversity was correlated with sediment granularity. Pearson correlation analysis showed that Shannon-Wiener index had highly significant positive correlation with a sand content and negative correlation with a silt-clay content （P〈0.01）; species richness index （d） had significant positive correlation with the sand content and negative correlation with the silt-clay content （P〈0.05）. The diversity of the southern Huanghai Sea was lower than that in the center of Bohai Sea, but the dominance was higher.

Spatial structure and species composition of soil seed banks in moving sand dune systems of northeast China

Soil seed banks can provide a mechanistic for understanding the recruitment dynamics and can inform conservation management of ecosystems. To investigate the contribution of soil seed banks to vegetation restoration in moving sand dune systems, we compared seed structure and species similarity between soil seed banks and standing vegetation among moving sand dunes, ecotones and dune slacks in northeast China. Average seed density in dune slacks was greater than in ecotones or moving sand dunes. Seed density in the soil layer of 0-10 cm was greater than at 10-20 cm both in the moving sand dunes and the eco- tones, but seed densities were similar at depths of 10-20 and 20-30 cm in moving sand dunes. Moreover, the spatial autocorrelation of seed density on moving sand dunes was weak but was strong on the ecotones and dune slacks. The species in the soil seed bank of moving sand dune systems were nearly all annuals, and the low similarity was mainly due to the lack of perennial species that were common in standing vegetation. Consequently, vegetation restoration cannot mainly rely on the soil seed banks in the movingsand dunes and more attention should be paid to protection of the dune slacks because they are the main source of seed disperse and seedling recruitment in moving sand dune systems.

Ecology and Species Composition of Fresh Water Snails in Amassoma Community and Niger Delta University Campuses, Bayelsa State, Nigeria

The knowledge about the population dynamics of freshwater snail intermediate host and their roles in disease transmission is little known in Bayelsa State. This study investigated the species composition of fresh water snail intermediate host in Amassoma community and the Niger Delta University Campuses during August 2019-October 2019 across five locations (Main campus Hostel, E.T.F Building, Ogboebi-Ama, Efeke-Ama, Ogbopina). Snails were collected from the water bodies with the aid of a scooping net and hand picking. The morphological identification of the snail intermediate host followed standard procedures. From the result, five hundred and seventy-one freshwater snails belonging to four genera and five species were recorded. The presence of Lymnae and Bulinus in the locations highlights foci for fascioliasis and schistosomiasis. The presence of Melanoides spp. is novel in Bayelsa State. The public health implications of these snails have called for timely control intervention.

Species composition,structure,regeneration and management status of Jorgo-Wato Forest in west Wollega,Ethiopia

Species composition,structure,regeneration,and management status of Jorgo-Wato Forest(JWF)was studied.Number of individuals,diameter at breast height(dbh)and height of woody species(dbh≥2.5 cm)were counted and measured in each plot.Group discussions with local farmers residing around JWF were carried out to understand the management of the JWF.Forest structural attributes were computed using descriptive statistics;correlation was used to assess relationships between the structural variables.A total of 4313 individuals(dbh≥2.5 cm)with a density of 1477 ha-1 were recorded,the number of species and individuals decreasing with increasing dbh classes.Species with the highest Importance Value Index(IVI)were Pouteria adolfifriedericii(37.7),Syzygium guineense subsp.afromontanum(23.6),Dracaena afromontana(20.5),Chionanthus mildbraedii(15.9),and Croton macrostachyus(12.3).Overall distribution of woody plants across size classes exhibited a reverse J-pattern,suggesting a healthy population structure and good regeneration.Nevertheless,some species were not represented in smaller diameter classes,including juvenile phases,which indicate a lack of regeneration.For these species,monitoring and enrichment planting would be necessary,along with curbing illegal cutting and coffee farming in the natural forest.Management interventions in the JWF need to consider livelihood options and to respect the rights of local communities.

A fuzzy distinguishability on species composition similarities of pelagic fishes in different years in the southern Taiwan Strait

A fuzzy mathematical method is used to discriminate the similarities of pelagic fishes land- ed in the 9180 hauls by 10 light-seine information vessels in the southern Fujian waters from 1989 to 1998. The results indicate that the dominant species of the communities had an obvious alternation and the fuzzy adjacency of annual species composition varied between 0. 659 and 0. 923 with an average value of 0. 791. The fuzzy clustering analysis indicates that the annual fuzzy adjacency in general remains good although the species composition of the pelagic fishes has changed to a certain degree since 1992. This paper concludes that the community structure of pelagic fishes in the southern Taiwan Strait remains rel- atively stable and the state of fish stocks shows a good potentiality for a larger utilization.

Species Composition and Diversity Analysis of Lava Flow in Different Periods in Wudalianchi Nature Reserve,China

The species composition and succession discipline after eruption of volcanoes in Wudalianchi Nature Reserve, China, including new volcanoes, such as Huoshao and Laohei Mountains, and old volcanoes, such as East Jiaodebu, Wohu and North Gelaqiu Mountains, in different historical periods were investigated by adopting the concept of space as a substitute for time. The species composition, community characteristics and diversity analysis in the remains of volcanic lava flow at various stages were analyzed. The results showed that 192 types of vascular plants that belonged to 50 families and 126 genera in the survey areas existed in the restoration process of primary succession. At the same time, the agglomeration process of plant community succession and the diversity of dominant community were investigated, and the changes in plant diversity at different succession stages were calculated using Margalef, Simpson, Shannon–Wiener, Pielou, Jaccard and Cody indices.

Species Composition and Protection of Fish Eggs and Larvae in Spawning Ground of Liaodong Bay

[Objective] The paper was to explore the species composition, number distribution and seasonal dynamics of fish eggs and larvae in Liaodong Bay in 2008. The protection and exploitation status of spawning ground in Liaodong Bay was analyzed, and the corresponding protection measures were put forward. [Methods] The species composition of fish eggs and larvae in spawning ground of Liaodong Bay was investigated by horizontal trawling associated with vertical trawling with zooplankton net in May, July, September and October in 2008. [Result] It was found that 7 724 eggs and 229 larvae of fishes belonging to 32 taxa were collected, in which 29 taxa were identified as species, belonging to 9 genera, 21 families and 28 orders, 2 taxa were identified to only family level, and one failed to be identified. The main spawning groups were Cynoglossus joyneri, Engraulis japonicus, Johnius belengerii, Larimichthys polyactis, Konosirus punctatus, Sardinella zunasi, and Scomberomorus niphonius, and the main spawning ground was found in northern waters and Changxing Island waters in Liaodao Bay. There was slightly less spawning species in 2008 compared with 1998, especially the number of fish eggs and larvae decreased greatly. [Conclusion] The effective measures for protection of spawning grounds in Liaodong Bay are suggested, including control of fishing intensity, development of artificial reefs, establishment of germplasm resources reserves, and standardization of compensation standards for marine ecological damage.

Plant species composition and diversity depending on piospheres and seasonality in the southern rangelands of Kenya

Introduction:Scarcity of water in the rangelands of Kenya has led to the introduction of piospheres.Previous research has however produced contrasting results on the effects of piospheres and seasonality on ShannonWiener’s diversity index,and therefore,this information is still deficient.In this study,the impact of these piospheres on plant species composition,diversity,and richness was assessed.Methods:Vegetation sampling was done during both the long rains(April)and the dry season(August).Three piosphere types(dam,trough,and a seasonal river)were studied using 0.25 m2 quadrats to sample vegetation at intervals of 20 m along 100-m transects.Four 100-m transects were used per piosphere(north,east,south,and west directions).Shannon-Wiener’s diversity index was used to determine species richness and composition.Twoway ANOVA was used to determine if piospheric distance had an effect on species diversity,richness,and evenness using GenStat 15th edition.Results:A total of 22 grasses and 29 forbs were recorded in the study area.The most abundant grasses near the piospheres were Eragrostis tenuifolia(12.9%)and Cynodon dactylon(10.6%).E.tenuifolia is an increaser species and was therefore most abundant in areas of severe grazing while C.dactylon has been known to be tolerant to grazing.The most abundant forbs were Crotalaria brevidens(37.5%).The Shannon-Wiener diversity index significantly increased(F=25.07,P=0.001)with distance from the three piospheres owing to the high grazing intensity near the piospheres and was significantly different between piospheres,being higher(F=10.05,P=0.001)at 20 m from the river(1.2±0.1)compared to a similar distance from the dam(0.9±0.1)and the trough(0.8±0.2).This was probably because the trough was smaller in size compared to the other piospheres,thereby concentrating more grazing animals per unit area and causing a greater impact on plant species.Conclusions:The study demonstrated that species diversity,richness,and evenness were low near the piospheres due to heavy grazing.Similarly,the lowest species diversity,richness,and evenness were recorded near the trough compared to the dam and the river.This study therefore recommends that range reseeding and rest period be done to rehabilitate degraded areas and facilitate plant regeneration.Larger piospheres should also be used to minimize animal impact per unit area.

The influence of cultivation frequency on weed species composition and diversity in flood recession farming in the Okavango Delta, Botswana

Introduction:Flood recession farming,locally known as molapo farming,is an important livelihood activity for the subsistence farming community around the Okavango Delta.The study was aimed at investigating the influence of cultivation frequency on non-crop species composition.It was carried out in the peripheral settlements of Shorobe,Makalamabedi and Lake Ngami.Methods:Vegetation sampling was conducted from March to April 2016 in 36 fields of varying historical cultivation frequencies.The cultivation frequencies were 5,10 and 15 years with an uncropped control site.Sampling was done in 1-m^(2) quadrats placed 10 m apart along a line transect.Shannon’s diversity and equitability indices were used to compare diversity for each cultivation frequency within and across the study sites.The Kruskal–Wallis test was used to investigate significant differences in diversity between cultivation frequencies.Rank of abundance was used to determine the association of weeds with the cultivation frequencies.Results:Cultivation frequency did not influence species diversity(p>0.05)at either Lake Ngami or Shorobe.Species evenness was significantly different(p<0.05)between the cultivation frequencies at Shorobe,but not at either Makalamabedi or Lake Ngami.There was a significant difference(p<0.05)in diversity indexes across the four cultivation frequencies.The 5-year frequency recorded the highest median score(Md=1.352)while the 15-year frequency recorded the lowest median score(Md=1.035).Corchorus tridens was the most abundant noncrop species at the 5-and 15-year frequencies.Cynodon dactylon was most abundant in the 10-year frequency while Cyperus esculentus was most abundant in uncropped fields.Conclusions:Cultivation frequency influenced weed species diversity and composition in flood recession farming.Flood recession farming fields were dominated by common weed species which are also troublesome in dryland arable farming.Uncropped sites were composed of wetland species that tolerate some dry periods or seasonal flood plains.

Species composition and quantitative variation of zooplankton in the Great Wall Bay and its adjacent waters，Antarctica

A preliminary identification has been made of 35 species of the zooplankton in the Great Wall Bay and its adjacent waters,Antarctica. The dominant species in the investigated area are Calanus propinquus, Calanoides acutus, Metrdia gerlachei and the larvae of antarctic krill.The results indicated that the zooplankton in the investigated waters were simple in species number, which conforms to the general pattern of the distribution of the zooplankton in antarctic waters.The total biomass and number of individuals of the zooplankton in the investigated waters showed obvious seasonal variation. In summer there were Calaninioides acutus and the larvae of antarctic krill; in winter there were Metrdia gerlacher, Calanus propinquus, Oithon similis, O. frigda and the larvae of antarctic krill. The quantity of Copepoda occupied a considerable proportion in each month. The water temperature is an important factor in controling the biomass of zooplankton.

Temporal Variation in Composition and Abundance of Phytoplankton Species during 2011 and 2012 in Acapulco Bay,Mexico

Phytoplankton samples were collected in Acapulco Bay during 2011 (January-April and September) and 2012 (April-July, October, and November) with the objective of determining the abundance and species composition. Samples were collected in two stations located in the bay. A total of 82 species were identified: 42 dinoflagellates, 35 diatoms, three cyanobacteria, and two silicoflagellates. Dinoflagellates were more abundant in the dry season, while diatoms dominated during rainy season. At least seven dinoflagellate species were recorded as potentially toxic, which may increase their populations and turn into harmful algal blooms (HABs) if environmental conditions within the bay are modified. In April 2012 a HAB of the non-toxic species Neoceratium balechii was documented.

Species composition, stand structure, and regeneration status of tree species in dry Afromontane forests of Awi Zone, northwestern Ethiopia

Species composition,structure,and regeneration status of trees were assessed in five dry Afromontane forests.In each of the forests,trees having≥5 cm diameter at breast height were identified and measured in 80 quadrats(20×20m^(2)).We compared tree species composition and similarities,stem densities,frequencies,basal area and importance value index of trees.Harvesting index was calculated to 13.3%in the least disturbed and 22.5%in highly disturbed forests.A total of 1,655 individuals representing 38 species and 28 families were recorded.The tree densities varied from 364.1 to 664.1stem ha^(−1) with an average basal area of 20.7m^(2) ha^(−1).The analysis showed significant differences in basal areas of tree species between the least and highly disturbed forests.Seedling densities ranged from 2000 to 8162.5 stem ha^(−1) and sapling densities ranged from 512.5 to 2562.5 stem ha^(−1).The anthropogenic disturbances revealed high degradation of population structure and regeneration statutes of the trees in the studied forest ecosystem.In conclusion,the study provided empirical results on the dominance,population structure,importance value and regeneration status of tree species,which would be instrumental for the development of successful rehabilitation strategies for the studied forests.

Urbanization strengthens the edge effects on species diversity and composition of woody plants in remnant forests

Background:Urban remnant forests are embedded in urban areas and are threatened directly and indirectly by urbanization.The direct effects(e.g.,loss of area)have been well studied.However,knowledge about the indirect influence of urbanization through edge effects on the biodiversity in remnant forests is limited.Methods:In this study,we surveyed woody plant species in 72 plots in nine remnant forest patches in Guiyang,China.We examined the influences of urbanization and edge effects on the species diversity and composition of woody plants in remnant forests.We compared alpha diversities and quantified compositional dissimilarities in interior and edge sites at different levels of urbanization.We also measured the niche width of the recorded plant species and assessed whether high levels of urbanization and edge effects increased the number of generalist species.Results and conclusions:The Shannon index,the Simpson index and the Pielou index of adult trees were lowest in the edge habitat under high levels of urbanization.Significant differences in the Shannon index and the Simpson index of sapling/seedling were detected between interior and edge sites under low urbanization.The edge effects on the species composition of adult trees were intensified by high levels of urbanization.Woody plant species with wide niche widths were more abundant at edge sites under high levels of urbanization.Therefore,we recommend that urban expansion surrounding remnant patches should be strictly controlled to alleviate edge effects on biodiversity.

Influence of edaphic factors on distribution and condition of Himalayan silver birch(Betula utilis D.Don)communities in the northwestern Indian Himalayas

The basic concept of phytosociology is crucial for the assessment of species composition and dynamic ecological succession of forests supporting ecological services,functions,disturbance,and resilience that lead to the development of integrated areas such as ecological niche modeling and contribute to identifying the valuable bio-indicators which can be used in framing conservation and management planning.B.utilis is one of the most dominant tree species of treeline ecotone in the Himalayan Region.The species is also considered as indicator species for monitoring the past and recent climate change impact.The current study was carried out in the natural populations of B.utilis from the sub-alpine zone of North-western Indian Himalaya.The birch dominated forest harbors a total of 305 plant species comprising Angiosperms(51 families,160 genera and 277 species),Gymnosperms(03 families,05 genera and 07 species)and Pteridophytes(07 families,11 genera and 21 species)with Asteraceae,Ranunculaceae and Rosaceae as dominant family.Birch forests are found dominant in shady moist habitat and North West aspect.Geographical characteristics,anthropogenic and developmental activities affect the population structure of B.utilis and associated species.However,the species has fair regeneration status in the study area.The acidic nature of soil pH and spatial variation in edaphic characteristics may be due to geographical differences,rooting patterns and litter accumulation of below and above-ground vegetation.Biomass estimation of a representative population of B.utilis from each site showed that TAGBD,TCD and TBD were found maximum in ST3(Hamta Pass II site).The CCA analysis determined that environmental variables such as altitude,organic matter,available phosphorous,organic carbon,available nitrogen,and electrical conductivity played a significant role in determining tree species composition and distribution in B.utilis dominated forests.

Fish Assemblage and Abundance Distribution in Nanji Islands Marine Nature Reserve in Relation to Season Change

The fishing survey station located in the warm waters of the East China Sea is one of the abundant fishery resources of waters;with a large number of economic fish breeding grounds and economic juvenile feeding grounds. Several fish species according to this bottom trawl survey results which appear in the annual survey from winter to autumn give us a total of 58 species, which have appeared throughout the year. But the vast majority of species appears only in certain seasons, according to the sea fish survey and based on seasonal migratory species or species mainly small endemic species. The survey of fish is tropical and subtropical warm water species and warm temperate species, and the history of the area has several types of 397 different species. There are many reasons, in addition to recent years, human disturbance and adverse consequences of environmental changes brought about, but also with the relevant sampling methods and sampler time, the survey sampled only trawl based, from Ping yang Ocean and Fisheries Bureau, the waters are still other jobs method net, gill nets, fishing industry, etc. Survey results show that the type of fish in the summer (58 species) > spring (55 species) > winter (51 species) > autumn (42 species). The type of season was among spring to summer rose, summer to autumn decline. The survey found that in the reef area of the Nanji Islands, no one species of fish is the dominant species throughout the year (according to the dominant species, each species is dominant only in one season). From the dominant species turnover accounting for the four seasons, in winter it has 53.72% of the total biomass or annual biomass, spring it has 41.53% of the overall biomass, summer it has 31.85% and autumn it has 38.56% of total biomass. Visible, seasonal succession of dominant species of fish phenomenon is very obvious, especially in the spring and winter, summer transfers dominate species at this stage show the greatest change, but winter, the transfer of this dominant species changes in minimal. Seasonal changes from biomass and the average annual marine fish survey biomass were 4832.25 g/h. From different seasons, the average biomass in winter (10779.88 g/h) > of the average biomass in spring (3624.1 g/hour) > of the mean biomass in autumn (3158 g/h) > the average Biomass in summer (1767 g/h). All of them show significant seasonal variation of the biomass, in winter and spring, the biomass is generally not high, but significantly higher than in the summer and autumn seasons. Each season, around the coast of southern Zhejiang, is less than the biomass and other catches off, which involves investigating sea location, size range, and the survey ship different network related tools. Another change from the area of biomass, some studies found that the survey of four-season fish of waters above the biological capacity of several kilograms only in some stations, namely stations and the highest biomass in summer appeared in stations 3, 7 and 11. In autumn the highest biomass appeared in stations 3, 6, 20 and 23.

Evolution of nutrient structure and phytoplankton composition in the Jiaozhou Bay ecosystem

The inventories of nutrients in the surface water and large phytoplankton(>69 μm) were analyzed from the data set of JERS ecological database about a typical coastal waters, the Jiaozhou Bay, China, from 1960s for N, P and from 1980s for Si. By examining long term changes of nutrient concentration, calculating stoichiometric balance, and comparing diatom composition, Si limitation of diatom production was found to be more possible. The possibility of Si limitation was from 37% in 1980s to 50% in 1990s. Jiaozhou Bay ecosystem is becoming serious eutrophication, with notable increase of NO 2 N, NO 3 N and NH 4 N from 0 1417 μmol/L, 0 5414 μmol/L, 1 7222 μmol/L in 1960s to 0 9551 μmol/L, 3 001 μmol/L, 8 0359 μmol/L in late 1990s respectively and prominent decrease of Si from 4 2614 μmol/L in 1980s to 1 5861 μmol/L in late 1990s; the nutrient structure is controlled by nitrogen; the main limiting nutrient is probably silicon; because of the Si limitation the phytoplankton community structure has changed drastically.