Lentic Zones Research Articles

Carbonate mineral dissolution and photosynthesis-induced precipitation regulate inorganic carbon cycling along the karst river-reservoir continuum, SW China

Damming alters the biogeochemical cycling of carbon along river systems. However, the effects of river damming on the fate and transport of particulate and dissolved inorganic carbon (PIC and DIC) remain unclear. Here, we use dual isotope (13C and 14C) compositions, water chemistry, and electron microscopy to unravel the processes controlling the in-reservoir cycling of inorganic carbon in a river-reservoir system of a karst region of southwest China. From the reservoir’s fluvial to lentic zone, δ13CPIC decreases from −2.2 ‰ to −7.6 ‰, whereas the PIC radiocarbon age drops from 11,512 to 2,027 years B.P. Electron microscopy images and water chemistry provide further evidence of in-reservoir photosynthesis-induced carbonate precipitation of autochthonous PIC in the water column. Although part of PIC is dissolved into DIC in the reservoir’s hypolimnion, the contribution of carbonate minerals (allochthonous PIC) accounted for 41 % of PIC based on an isotopic mass balance model. This indicates that the precipitation rate of autochthonous PIC was greater part of carbon cycle in the reservoir. Moreover, the autochthonous PIC accounted for 61 % of the PIC and its dissolution accounted for 50 % of the DIC and the high CO2 efflux in the water discharging from the reservoir. The results shed light on the important role of autochthonous PIC in carbon cycling in karst river-reservoir systems. With continued dam construction in karst areas, the role of in-reservoir PIC production and dissolution on the riverine carbon cycle deserves more attention.

Use of geographical information systems (GIS) in assessing ecological profile, fish community structure and production of a large reservoir of Himachal Pradesh.

The present study demonstrates the spatial analysis and mapping of fish and different measures of environmental parameters and fish diversity of Pong reservoir, Himachal Pradesh, using Kriging spatial interpolation methods for geographical information system mapping. Seasonal data on environmental parameters, potential fish habitat and fish diversity was collected from lentic (dam), lentic (reservoir), transitional and lotic zone of the reservoir.. Important environmental parameters like water temperature, dissolved oxygen, electrical conductivity, water depth and transparency showed variations across the different zones of the reservoir. The sediment of the reservoir was sandy clay loam in nature as per texture analysis. Fish species richness, Shannon index and evenness index showed a similarity of the lotic and lentic (reservoir) zones of the reservoir. Six potential fish breeding grounds were identified in the reservoir indicating high conservation significance. The analysis of data showed a declining trend in fish production from 456.9 tonnes during the decade 1976-1987 to 347.91 tonnes during 2009-2020. The factors like anthropogenic climate change, predation of a stocked fish juvenile by water birds, undersized fish stocking and unscientific management are the probable reasons for the decreasing fish production. The spatial variation pattern of the water spread area, environmental parameters, fish catch and potential fish breeding grounds depicted in the GIS platform can be used as an important information base by the policy makers for fisheries management. The stocking of large size fish as a stocking material and adequate protection of the potential fish breeding grounds are the key advisories for the sustainable enhancement of fisheries as well as conservation.

Multifaceted fish diversities respond differently to impounding age and longitudinal location along a reservoir cascade

Damming usually modifies riverine habitats, which affects various aspects of fish diversity, especially in a reservoir cascade. Their influence on fish assemblage has been studied widely, but a lack of data from the diversity perspective remains. The Gezhouba Reservoir and Three Gorges Reservoir are two of the largest cascaded reservoirs located on the upper Yangtze River. In this study, we investigated the current fish assemblages in 2020∼2021 and retrieved 22 previous investigations in different sections of this cascade system to analyze how fish taxonomic, functional, and phylogenetic alpha- and beta-diversity change with the distance from the dams and the impounding age during 1998∼2021, and all sampling sites are located in the upper section of the dams. The total species richness and phylogenetic diversity increased significantly with the distance from the dams, but the functional diversity did not change substantially. No significant difference was found in the influence of impounding age on the three aspects of fish diversity. We observed a noticeable increase in non-indigenous fish species richness, functional diversity, and phylogenetic diversity over time, these effects were similar in areas at different distances from the dams. The species richness and phylogenetic diversity of lotic fish decreased from the lotic to lentic zones, whereas the functional and phylogenetic diversities decreased significantly with impounding age. The taxonomic beta-diversity was remarkably higher than the functional and phylogenetic beta-diversities. The differences among the three facets of beta-diversity were driven by a lower functional turnover than the taxonomic and phylogenetic turnovers, and their nestedness components were low without exception. The present study suggests that trade-offs should be considered when designing policies to protect fish diversity based on different objectives.

Longitudinal habitat gradient affects diet and body condition of riverine fish: A case study of Pelteobagrus catfishes in the Three Gorges Reservoir, China

AbstractTo understand how riverine fish respond to longitudinally different habitats created by impoundment, we selected three congeneric yellow catfish species (Pelteobagrus spp.) as a model system to assess changes in diet, prey selectivity, and body condition among the lotic, transitional, and lentic habitats along the Three Gorges Reservoir. Our results add to previous findings highlighting a shift in fish diets from diverse zoobenthos to shrimp‐dominated as the river becomes lentic by showing spatial segregation in the size of shrimp prey consumed. Relative to the available shrimp populations, catfish populations selected smaller shrimp in the upper (lotic) section and larger shrimp in the middle (transitional) and lower (lentic) sections. Complementary body condition indices exhibited a consistent spatial pattern, where populations in the lotic zone were healthier than those in the transitional and lentic zones. This pattern seems to result from a greater nutrient value of zoobenthos, the dominant food in the lotic zone, relative to shrimps. Our results suggest that these generalist fish species have adapted to the spatial habitat gradient and maintained their populations, but the impoundment has deeply influenced their energy acquisition and allocation.

Status of the Freshwater Molluscs from Krishna River, Satara, (MS) India

A total 18 freshwater mollusc species with all forms and varieties belonging to 04orders, under 10 families. the maximum diversity was found in order Mesogastropoda and minimum was from Basommatophora. The dominant species among these total molluscs belonged to the Unionidae family.The abundance of freshwater mollus can species in the Krishna River is described in an assessed checklist. Molluscs are widely regarded as the most diverse and dominant benthic fauna in both the lentic and lotic zones. Regional populations of malacofauna, on the other hand, may be attributable to the quantity of planktonic mass at different river sites, which reflects mollus can species diversity.

Comparative Assessment of Physico-Chemical Parameters of Lotic and Lentic Zone of River Betwa in Jhansi (U.P.), India

Water is the most precious natural gift given by God to human race. Its purity is also important for everyone. For the present study two sampling stations, Baratha village and Parichha dam head were selected for comparative assessment of physico-chemical parameters of lotic and lentic zones on Betwa river. Both these sampling stations are located at Jhansi (UP) India. Samples were collected regularly for one complete year from July 2018 to June 2019. Eighteen water parameters and four hundred thirty two samples were analysed. The overall mean ranges of these parameters at Baratha village and Parichha dam head were notified as electric conductivity (518.66±43.47) and (528.75±59.65), pH (8.09±0.36) and (8.14±0.26), water temperature (24.37±4.14) and (23.78±4.12), transparency (54.91±4.97) and (41.61±3.83), turbidity (30±12.38) and (35.25±16.38), TDS (265.33±16.74) and (267.66±25.42), TSS (66.5±12.52) and 69.83±14.45), TS (331.83±28.76) and (337.5±39.04), DO (6.76±0.68) and (6.72±0.86), total alkalinity (141.58±22.74) and (142.25±29.37), total hardness (150.08±22.70) and (153.66±20.55), Ca (29.04±2.32) and (29.84±5.38), Mg (13.51±2.01) and (14.32±2.20), chloride (24.77±3.29) and (26.85±3.99), BOD (4.08±0.71) and (4.15±1.16), COD (11.64±1.02) and (12.82±1.20), NO3 (1.64±0.37) and (1.93±0.59), PO4 (0.46±0.21) and (1.33±0.29). All these findings concluded that the lentic zone (Parichha) is more polluted than the lotic zone (Baratha). However all the observed values are in the range of permissible limits, so both zones can be used for irrigation and fisheries sector.

Dispersal of fish eggs and larvae in a cascade of small hydropower plants with fish ladders

This study was conducted to investigate fish eggs and larvae dispersal in a river stretch influenced by small hydropower plants in Southeast Brazil. The main hypothesis is that the downstream dispersal of free-flowing eggs and larvae is likely to occur given the small size of the studied reservoirs and that passage through the dam may occur, with the fish ladder contributing to it. Eggs and larvae were collected fortnightly, between November 2016 and February 2017, from locations upstream of two dams, including lotic, transition and lentic zones. Additional samples were collected inside the fish ladders at each dam. Downstream dispersal of eggs and larvae was influenced by a combination of rainfall/flow variation and stage of the reproductive cycle, with the peak of rainfall during the summer coinciding with higher abundances. Under these conditions, eggs and larvae drifted downstream through the reservoirs and reached the dams. Once in the dam, they could pass through the fish ladder. This passage was correlated with larval density in the reservoir immediately upstream, although at very low densities compared with the other sampling sites located upstream of the fish ladders.

Artificial flow regime promotes abiotic and biotic gradients: Testing the concept of longitudinal zonation in an off-river reservoir

Fragmentation and interconnection of water bodies cause severe changes in the natural flow regime of continental water systems. However, assessments of these impacts on the freshwater fish distribution are still scarce. We investigated whether an artificial flow regime generated by discharges from an aqueduct would promote a longitudinal environmental gradient in an off-river reservoir. We tested the hypothesis that the incoming water from aqueduct discharges promotes environmental gradient between lotic and lentic conditions. We expect that environmental changes and the artificial flow regime promote the structuring of fish assemblage and that the lotic-lentic transition areas present the highest fish species richness. A longitudinal gradient in environmental characteristics with differing fish assemblage structure was found. Temporal changes in the fish assemblages occurred only in areas near the discharge of the aqueduct. The highest fish richness and diversity were recorded in the transition zone during the wet season, associated with the greater environmental heterogeneity of this ecotone, whereas the lowest was found in the lotic zone, probably associated with the altered flow regime. The greatest abundance was recorded in the upper lentic zone in the wet season, whereas the lowest was found in the lower lentic zone in both seasons. Our results corroborate the hypothesis that the artificial flow regime, modulated by the seasonality of discharges and the influence of environmental variables, promotes longitudinal gradients in reservoirs when rivers are not present. The findings are relevant in a scenario where ever more interconnections of aquatic bodies have been diffused around the world.

A faunistic and ecological characterization of the water mites (Acari: Hydrachnidia) of the Branew River (central-eastern Poland)

A characteristic feature of the Hydrachnidia communities of the Branew River, distinguishing its fauna from that of other Polish rivers, was the very high abundance of species of the genus Lebertia. Species of this genus accounted for as much as 53.1% of the collected material. The most numerous was Lebertia rivulorum, which was caught in numbers not found in other Polish rivers. Lebertia inaequalis and L. oblonga were also abundant. The largest synecologi-cal groups were rheophiles and rheobionts (94.9% combined). More individuals (1494) and species (27) were caught in the lentic zone of the river than in the lotic zone (1291 ind., 25 sp.). The species most associated with the lotic zone was L. rivulorum. This species was caught mainly on a substrate of gravel and stones with a small amount of sandy sediments, sparsely covered with Elodea canadensis. The species most associated with the lentic zone was Forelia variegator. The most abundant species in the Branew River, Hygrobates setosus, was caught in much higher numbers in the littoral zone than in the central part of the river. The high similarity of fauna was observed between the lotic and lentic zones, and much lower similarity between sites. The results indicate intensive species migration in the transverse profile of the river and low migration in the longitudinal profile. Higher species diversity was recorded in the lentic zone than in the lotic zone of the river – both in the river as a whole and at the individual sites. In the anthropogenically transformed stretch of the river (straightened riverbed, concrete dam, and concrete bottom), species diversity was significantly lower (H’ = 1.83) than in the natural stretch (H’ = 2.37). The results confirm literature data describing the negative impact of such transformations on Hydrachnidia communities. Despite anthropogenic transformations in parts of the river, the structure of the fauna (a very large proportion of rheobionts and rheophiles), as well as the physicochemical parameters of the water, is indicative of the good ecological condition of the river.

Species-specific variations in reproductive traits of three yellow catfish species (Pelteobagrus spp.) in relation to habitats in the Three Gorges Reservoir, China.

The reproductive biology of three yellow catfish congeners was studied in the Three Gorges Reservoir of the Yangtze River, China. We compared reproductive traits among the lentic, transitional, and lotic zones. A total of 4502 individuals of the three species was collected, and the sex ratio, size at 50% maturity, spawning season, fecundity, and egg size were determined. Results showed that populations inhabiting the lotic zone spawned earlier than those inhabiting the lentic zone. For the three species, fecundities were significantly higher for populations in the lotic zone than for those in the lentic and transitional zones (P < 0.05). Pelteobagrus vachelli (Richardson) and P. fulvidraco (Richardson) displayed an obvious trade-off between egg size and fecundity, whereas P. nitidus (Sauvage et Dabry) produced the largest eggs in the lotic zone. Sex ratios were significantly different among zones (P < 0.05, for each species), but the bias patterns were different. Sizes at 50% maturity of female P. nitidus and P. vachelli were the largest in the lotic zone and the smallest in the transitional zone, but was similar among zones for P. fulvidraco. Overall results suggest that the three yellow catfish species developed different reproductive traits among the three habitats in the TGR, whereas the variations reflected further interspecific differences. Our study indicates the importance of riverine habitats for the conservation of species of fish, even for species such as these eurytopic catfish inhabiting the upper reach of the Yangtze River. This study further suggests that species-specific responses should be considered when evaluating the influences of new hydropower projects, even for such closely related species of fish.

A faunistic and ecological characterization of the water mites (Acari: Hydrachnidia) of the Bukowa River (central-eastern Poland)

A characteristic feature of the Hydrachnidia communities of the Branew River, distinguishing its fauna from that of other Polish rivers, was the very high abundance of species of the genus Lebertia. Species of this genus accounted for as much as 53.1% of the collected material. The most numerous was Lebertia rivulorum, which was caught in numbers not found in other Polish rivers. Lebertia inaequalis and L. oblonga were also abundant. The largest synecologi-cal groups were rheophiles and rheobionts (94.9% combined). More individuals (1494) and species (27) were caught in the lentic zone of the river than in the lotic zone (1291 ind., 25 sp.). The species most associated with the lotic zone was L. rivulorum. This species was caught mainly on a substrate of gravel and stones with a small amount of sandy sediments, sparsely covered with Elodea canadensis. The species most associated with the lentic zone was Forelia variegator. The most abundant species in the Branew River, Hygrobates setosus, was caught in much higher numbers in the littoral zone than in the central part of the river. The high similarity of fauna was observed between the lotic and lentic zones, and much lower similarity between sites. The results indicate intensive species migration in the transverse profile of the river and low migration in the longitudinal profile. Higher species diversity was recorded in the lentic zone than in the lotic zone of the river – both in the river as a whole and at the individual sites. In the anthropogenically transformed stretch of the river (straightened riverbed, concrete dam, and concrete bottom), species diversity was significantly lower (H’ = 1.83) than in the natural stretch (H’ = 2.37). The results confirm literature data describing the negative impact of such transformations on Hydrachnidia communities. Despite anthropogenic transformations in parts of the river, the structure of the fauna (a very large proportion of rheobionts and rheophiles), as well as the physicochemical parameters of the water, is indicative of the good ecological condition of the river.

Diet Composition and Foraging Habitat Use by Three Species of Water Snakes,HelicopsWagler, 1830, (Serpentes: Dipsadidae) in Eastern Brazilian Amazonia

Abstract Water snakes of the genus Helicops have different uses of food resources that can facilitate species coexistence. To assess diet and foraging habitat of water snakes in eastern Brazilian Amazonia, we used prey consumed by Helicops angulatus, Helicops hagmanni, and Helicops polylepis deposited in scientific collections to analyze variations in composition, breadth, and niche overlap on a regional scale. Among these prey, we used fish (main item) to calculate ecomorphological attributes that might indicate fish habitat and, consequently, the foraging habitat used by snakes. Our analyses indicate these three snake species have similar diet compositions but differ in the proportion in which each item is consumed. Helicops angulatus had the most generalized diet and H. hagmanni had the most specialized diet. Food niche overlap among the three species was moderate. All three species forage in the medium and upper strata of the water column in the lentic zone; however, H. polylepis feeds on prey with va...

First Record of the Dirt-Colored Seed Bug,Sisamnes claviger(Heteroptera: Rhyparochromidae: Myodochini) in Illinois

The heteropteran fauna of Illinois is diverse and well-surveyed, comprising approximately 680 species distributed among 40 of the 57 families represented in the Nearctic region (Henry and Froeschner, 1988; Swanson, unpublished). This diversity arises, in part, from the state’s latitudinal extent, as well as from the varied habitats present in the state, ranging from dune land bordering Lake Michigan in the northeast to large tracts of old growth forest in the Shawnee National Forest and bald cypress/tupelo swamps in the south. Also present is a generous array of riparian, lentic and lotic zones, seep springs, cave systems, and various discrete tall grass, sand, hill, and floodplain prairie ecosystems (White and Madany, 1978; Schwegman, 1987; Taylor et al., 2009). Consequently, the early development of natural history programs catalyzed the accumulation of knowledge regarding the region’s biota (Post, 1991). Despite Illinois’ strong history of biotic surveys extending back into the first half of the 19th century, new records of native species are still being discovered within its borders (e.g., Tin erella et al., 2009; McPherson et al., 2011). In the fall of 2012, as part of a larger insect bioinventory, two of the authors (ADY and SJT) collected a specimen of a minute, rarely encountered lygaeoid in a pitfall trap laid in the Braidwood Dunes and Savanna Nature Preserve (Will County, northeastern Illinois). Discovered in the lot of Braidwood heteropteran samples sent to DRS, the specimen (Fig. 1), a single adult male, was identified as Sisamnes claviger (Uhler, 1895), a species previously unknown from Illinois. This individual, preserved in ethanol, has been deposited in the Illinois Natural History Survey Insect Collection, University of Illinois at Urbana-Champaign, Champaign, Illinois (INHS), and bears the following label data: ILLINOIS: Will Co., Braidwood Dunes & Savanna Nature Preserve, 1.5 km SE of Braidwood on IL 113, 41.25290N -88.19970W, Site 189 (mesic sand prairie), Pitfall trap: B, 18 August 2011–2 September 2011, Sample Number: 5010, Lot Number: BRD 32204, Collectors: A. D. Yanahan, S. J. Taylor, det. D. R. Swanson 2013, INHS Insect Collection 780,190. Details of the collecting event, including a discussion of the habitat, are treated later in the text. Volume 124, Number 5, April 2015 357

An annotated checklist of fish fauna of Bukit Merah Reservoir and its catchment area, Perak, Malaysia

The fish fauna was surveyed at Bukit Merah Reservoir of Perak (one of the oldest reservoir in Peninsular Malaysia) and its catchment areas. A total of 47 species from 19 families were recorded: 38 fish species were recorded from eight sampling stations located in selected tributaries (lotic zone), while another 25 fish species were recorded in the reservoir itself (lentic zone). Based on a combination of previously published checklists and the present survey, a total of 76 fish species were recorded at Bukit Merah Reservoir. Out of these species, 25 fish species from this survey were new records. Most of the new records were found in the catchment area of the river basin. The presence of two alien species, Oreochromis niloticus and Clarias gariepinus, should be noted as these species could affect the population of native species.

Oligochaeta of the Danube River — a faunistical review

AbstractThe aim of this work is to discuss the distribution of Oligochaeta (Annelida) in the Danube River using the collections made by the Joint Danube Survey 2007 (JDS2) on more than 2800 km of the river. The basic faunistical features of the oligochaete assemblages were analysed with regard to three main sectors of the Danube (upper, middle and lower reaches, the last with the Danube Delta). A total of 52 oligochaete taxa have been recorded. Most of the observed species are typical of the potamon-type rivers in the region, and are well adapted to moderate-to-high organic load. The highest taxa richness and frequency of occurrence were observed among the Tubificidae family. Naididae, Propappidae, Enchytraeidae and Haplotaxidae had also low frequency. The upper reach of the Danube showed the lowest species richness, while the middle reach is characterised by its highest species richness. Construction of dams and regulation of the riverbed have resulted in an increase of limno(rheo)philic taxa which prefer slow-flowing and lentic zones.

Helminths of freshwater fishes in the reservoir of the Hydroelectric Power Station of Itaipu, Paraná, Brazil

This study presents results from several expeditions in 1985, 1991-1995 and 2003 to the Medium Paraná River in the section that begins below the Itaipu Dam and ends at the trinational border of Brazil, Argentina and Paraguay, in the lotic and lentic zones of the reservoir of the Hydroelectric Power Station of “Itaipu Binacional” (localities Foz do Iguaçu, Santa Helena and Guaira). Ninety-eight species of freshwater fishes belonging to 22 families were examined for helminths. A host-parasite list based on Acanthocephala, Cestoda, Digenea, Monogenea and Nematoda collected from the region in question is provided. New host records are presented for Digenea and Nematoda. The Monogenea and Acanthocephala are being studied and will be published in a later paper, but are referred in the host-parasite list, in order to demonstrate the parasitism in the fishes of the reservoir. The results are compared with those presented by other authors from the Upper Paraná River.

Influence of the river flow on the structure of fish assemblage along the longitudinal gradient from river to reservoir

Changes in fish assemblage structure along a longitudinal gradient of the Paraiba do Sul River and Funil reservoir were studied to detect distribution patterns and the seasonal influence of the inflowing river. Fish were caught by gill nets in three zones (riverine, transition and lentic) during two seasons (dry and wet). A total of 3,721 individuals were captured, comprising five orders, 14 families, 27 genera and 33 species. Five species were non-native and amounted to 17.7% of the total number of individuals. The 10 most abundant species were used to assess spatial-temporal patterns. Plagioscion squamosissimus (Heckel, 1840), Oligosarcus hepsetus (Curvier, 1829) and Metynnis maculatus (Kner, 1858) were widely distributed in both seasons. Astyanax bimaculatus (Linnaeus, 1758), Cichla kelberi Kullander & Ferreira, 2006 and Geophagus brasiliensis (Quoy & Gaimard, 1824) had higher abundance in the dry season, occurring mainly in the lentic zone. By contrast, the benthopelagics Pimelodus maculatus La Cepede, 1803 and Astyanax parahybae (Eigenmann, 1908) and the benthics Hoplosternum littorale (Hancock, 1828) and Hypostomus auroguttatus Kner, 1854 had higher abundance in the wet season, with the two first species occurring mainly in the riverine zone, and latter two species in the transition zone. The highest diversity for both seasons was recorded in the transition zone, which is an ecotone that allows the co-existence of both riverine and lentic species. A major shift in assemblage structure occurred along the longitudinal gradient due to changes in discharge of the inflowing river, with increased fish abundance in the riverine zone caused by increased habitat availability in wet season, and the reverse of this situation in the dry season.

Microhabitat Use by Stream-Dwelling SpirlinAlburnoides bipunctatusand Accompanying Species: Implications for Conservation

Microhabitat use in the endangered cyprinid species spirlin Alburnoides bipunctatus and accompanying species was examined in three water courses of Slovakia to determine the species' environmental requirements as a basis for informing conservation policy and management. In all three rivers, water velocity, water depth and substratum character were central features of spirlin microhabitat use, regardless of year or season of sampling, with only limited variation in microhabitat associations as a function of time of day. Clear differences in microhabitat use and intra-specific associations during development were observed in two of the rivers. In particular, a shift in velocity preference towards faster flowing waters appears characteristic of spirlin during their larval and juvenile development, and possibly also that of gudgeon Gobio gobio, European minnow Phoxinus phoxinus, and chub Leuciscus cephalus, which are all species that may be significantly associated with young spirlin. Disproportionate use of deeper waters tended to increase with age in spirlin, and in gudgeon and barbel Barbus barbus, but spirlin preference for substratum was less uniform, with affinities ranging from indifference to strong preference. This contrasts the clear preferences for sand in gudgeon and for cobbles in European bullhead Cottus gobio. Of particular importance to young-of-the-year (YOY) spirlin are lentic zones with some sort of ligneous debris — habitat also used by YOY gudgeon and minnow. Contrary to previous reports elsewhere, spirlin did not avoid in-stream vegetation where present, and in one river it was preferred by YOY and 1 spirlin. To avoid declines in spirlin and accompanying stream-dwelling species, such as reported elsewhere in Europe, river management in water courses such as these should be limited to the rehabilitation of regulated sections to achieve a natural, heterogeneous channel character.

아까시나무림의 군락분류와 군락생태

아까시나무 우점림의 식생유형에 대한 분류와 분포양식 그리고 생태식물상적 특성을 규명하였다. 전통적인 식물사회학적 방법과 식생조사자료 및 식생유형간의 유사성 분석을 위하여 주좌표분석법(Principal Coordinates Analysis)과 상관 계수(correlation coefficient)가 이용되었다. 생태식물상의 분석에는 출현 식물종들의 특질(넌출형, 일이년생 생명환, 삼림식생요소, 체감도시화지수)이 이용되었다. 이러한 분석은 출현종의 상대기여도를 바탕으로 하는 입지-식생조사구 매트릭스의 식물군락표 및 군락합성표를 토대로 이루어졌다. 아까시나무 우점림은 총 77과 193속 323종으로 이루어져 있었으며, 아까시나무-닭의장풀군집(전형아군집, 떡갈나무아군집, 자귀나무아군집, 소나무아군집, 굴참나무아군집, 가중나무아군집), 아까시나무-갈대군락(전형하위군락, 띠하위군락)으로 분류되었으며, 크게 네 가지 식생형(도시형, 농촌형, 하천형, 복합형)으로 구분되었다. 아까시나무-닭의장풀군집은 졸참나무-작살나무아군단의 냉온대 남부 저산지대의 아까시나무 조림식생을 대표하는 식생단위이며, 아까시나무-갈대군락은 하천(정수역)형으로 기재되었다. 가중나무아군집은 높은 체감도시화지수에 의하여 도시형 아까시나무림으로 규정되었다. 하천형을 제외한 우리나라의 아까시나무 우점림은 지속군락으로 고려되었다. The black locust (Robinia pseudoacacia L.) forests were studied by a phytosociological approach. Particular attention was given to characterize the vegetation classification, distribution pattern, and ecological flora of the syntaxa classified. A total of 38 releves were analyzed by using Correlation coefficient, UPGMA as the clustering method, and Principal Coordinates Analysis for ordination. Ecological flora analyzed by plant character sets such as scrambler, annual and biennial plants, forest elements, and actual urbanization index. The analyzed data are based on site-releve matrix with relative net contribution degree (r-NCD) of species. A total of 77 families, 193 genera and 323 species of vascular plants are recorded. Camellino-Robinietum pseudoacaciae ass. nov. and Phragmites-Robinia pseudoacacia community were described. Main cluster and ordination could be separated: 1) urban type, 2) rural type, 3) riparian type, and 4) combined type. It is defined that the Robinietum is a representative unit on the black locust afforestation, Phragmites-Robinia community on the lentic zone in the river ecosystem, and Cameliino-Robinietum ailanthetosum altissimae as an urban forest type. The Robinietum was considered as a perpetual community.

MULTIVARIATE ANALYSIS OF WATER QUALITY IN THE RICHIBUCTO DRAINAGE BASIN (NEW BRUNSWICK, CANADA)1

ABSTRACT: Specific conductivity, pH, dissolved oxygen, carbon, phosphorous, and nitrogen species were measured at 36 stations in the Richibucto River drainage basin, including the estuary, in New Brunswick, Canada, over the six‐year period 1996 through 2001. Each station was sampled between 1 and 26 times (mean = 7.5, standard deviation = 6.0) during the ice free seasons without regard to tide. There was significant variance among stations in most parameters. Principal component analysis (PCA) was used to identify the processes explaining the observed variance in water quality. Because of the high variability in specific conductance, stations were first grouped in a freshwater subset and an estuarine (brackish water) subset. For freshwater stations, most of the variance in water quality was explained by pH and total organic carbon, as well as high nutrient concentrations. These high nutrient concentrations, along with water salinity, which varies with flow and tides, are also important in determining water quality variability in brackish water. It is recommended that water quality parameters that were found to explain most of the variance by PCA be monitored more closely, as they are key elements in understanding the variability in water quality in the Richibucto drainage basin. Cluster analyses showed that high phosphorous and nitrate concentrations were mostly found in areas of peat runoff, tributaries receiving treated municipal effluent, and lentic zones upstream of culverts. Peat runoff was also shown to be acidic, whether it is runoff from a harvested area or a natural bog.