Structure Of Ichthyofauna Research Articles

Характеристика структурных изменений ихтиофауны в северной части Аграханского залива за последние 5 лет

The northern part of the Agrakhan Gulf, which is a part of the Tersko-Caspian fishery complex of Dagestan, plays an important role in the formation of stocks of commercial fish species, having abundant spawning, nursery and wintering grounds. The efficiency of natural reproduction of fish is determined by the state of the hydrological and hydrochemical regime in the reservoir, which in recent years in this reservoir can be characterised as unfavourable. Studies carried out in North Agrakhan in the period from 2018 to 2022 have shown negative changes in the structure of ichthyofauna, manifested in a decrease in the number of juveniles of passable, semipassable, freshwater fish species and an increase in tuvodny fish of the lake-river complex. The number of juveniles of passable fish species has decreased almost twofold, kutum stocks have reached a critical level, the prevailing semi-passable fish species, which account for up to half of the total volume of recorded juveniles, are also decreasing, although to a lesser extent. Freshwater fish species are in a depressed state, the number of juvenile fish is decreasing from year to year, and has decreased more than twofold over the 5 years under study. The total number of segolets of low-value fishery lake-river fish species for 5 years increased 2 times and was 37% of the total volume of all fish species. In general, in the northern part of the bay the dominance of fish species in the northern part of the bay has become dominant among passable fish species - redfish, semipassable fish species - bream, freshwater fish species - redfish, lake-river fish species - redfish and crucian carp. Such species as kutum, pikeperch and practically all freshwater species are at the stage of extinction, mainly tench, which was recorded in catches only once.

Pro-ecological and conservation activities are not always beneficial to nature: a case study of two lowland streams in Central Europe

Since 1990 and in particular, after the implementation of the Water Frame Directive, many positive effects of pro-ecological projects are evident; unfortunately, examples of adverse effects have also been observed. This study aims to indicate how some ill-considered actions, called “pro-ecological”, may lead to habitat degradation and the disappearance of valuable hydrobiont species. Two watercourses, representing the lowland gravel stream and sandy stream type, were selected for the study. Literature indicated that in the past, these watercourses were characterized by an excellent ecological status and the presence of valuable rheophilic fauna and flora. Environmental parameters were recorded, macroinvertebrates and ichthyofauna were sampled and analyzed, and finally, indexes were calculated. The results were compared with literature data. In the course of studies conducted in 2011–2015, drastic habitat deterioration and extensive changes in the species structure of ichthyofauna and aquatic invertebrates were observed. Changes in the Smolnica stream have been caused by the three retention basins constructed in 2000, along the lower and middle course; while in Kiszewko, however, the factor for habitat deterioration was connected with the excessive expansion of the Eurasian beaver (Castor fiber), which created a beaver pond 20 m in width, with impoundment elevations of up to 2 m.

Natural reproduction of commercial fish in the Northern Agrakhan under modern conditions

The northern part of the Agrakhan Bay (Northern Agrakhan) has an important fishery importance in the Tersko-Caspian region of the Dagestan River, being a buffer zone where fresh and salt waters mix, therefore it plays a peculiar role of a receiving water body for passable and semipassable fish species migrating to spawning and wintering in the middle and lower reaches of the Terek River. Formation of stocks of commercial fish species in this part of the bay is currently taking place under conditions of reduced efficiency of natural reproduction, which is determined by the conditions of the hydrological and hydrochemical regime. In recent years, anthropogenic factors have caused profound negative changes in the structure of ichthyofauna in the Agrakhan Bay, and the water fishes of the lake-river complex began to dominate and the commercially valuable fish species of passage and semi-passage fish species began to decrease. Studying the dynamics of the number of recorded juveniles of commercial fish species allows not only to assess the efficiency of their reproduction, but also to determine the main causes affecting the reduction or increase in the stocks of various populations. The performed studies allowed to analyze the dynamics of changes in the number of recorded juveniles of commercial fish species that occurred over the last 5 and 10 years. It was confirmed that at present in the bay’s reservoirs low-value fish species are well adapted to the changed unfavorable conditions, as evidenced by the results of reproduction — the number of juvenile silver carp, redfish, perch and gouster increases from year to year. At the same time, against the background of unfavorable hydrological and hydrochemical regime and increased overgrowth of the bay, the migration activity of producers of passable and semipassable species decreases, leading to deterioration of fish reproduction results, which is confirmed by a decrease in the number of recorded juveniles of valuable species: kutum, redfish, vobla, catfish, pike, etc.

Cage fish farming as a driver of changes in the functional diversity and structure of ichthyofauna in a Neotropical reservoir

Cage fish farming as a driver of changes in the functional diversity and structure of ichthyofauna in a Neotropical reservoir

Coral reef fish assemblages exhibit signs of depletion in two protected areas from the eastern of Los Canarreos archipelago (Cuba, Caribbean Sea).

Understanding the impact of marine protected areas on the distribution and composition of fishes is key to the protection and management of coral reef ecosystems, and especially for fish-based activities such as SCUBA diving and recreational fishing. The aim of this research is to compare the ichthyofauna structure in three areas in the eastern part of Los Canarreos archipelago in Cuba with different management schemes: Cayo Campos-Cayo Rosario Fauna Refuge (CCCR), Cayo Largo Ecological Reserve (CL) and non-protected area (nMPA), and considering habitat differences and depth variation. A total of 131 video transects were conducted using diver operated stereo-video (stereo-DOV) in November, 2015 in backreef and forereef along the CCCR, CL and the adjacent nMPA. We recorded 84 species and 27 functional groups suggesting high complementarity of functions. Several multispecies schools were observed along surveys, which explain the biomass peaks in some sites, mainly for Lutjanidae, Haemulidae and Carangidae. A concerning issue was the bare representation of critical functional groups and threatened species. The effect of sites nested within habitats was significant and the most important driver structuring fish assemblages, while MPA condition was not evident. Favorable habitat features (habitat heterogeneity and surrounding coastal ecosystems) are likely enhancing fish assemblages and counteracting the effects of pouching derived from insufficient management. We recommend immediate actions within a strategy of precautionary management including, but not limited to, the appointment of staff for the administration of CL, frequent monitoring and effective enforcement.

PRELIMINARY DATA ON THE ICHTHYOFAUNA STRUCTURE FROM THE NORTHERN PART OF THE ROMANIAN BLACK SEA COAST

In the context of climate change observed in recent decades and taking into account the Danube input from the northern part of Romanian Black Sea waters, a research survey was conducted in order to obtain data regarding the ichthyofauna structure. During the survey conducted with the research vessel “Steaua de Mare 1” in 2019, 20 pelagic hauls and 4 fishing stations with gillnets of different mesh sizes were carried out. In pelagic trawling, 20 fish species have been identified, the dominant species being sprat (Sprattus sprattus) and whiting (Merlangius merlangus euxinus). In gillnet experimental fishing, 16 species were identified, Caspian shad (Alosa tanaica) and Danube shad (Alosa immaculata) being dominant. Also, in order to estimate the ichthyofauna biological diversity, the Margalef Index was calculated, values between 3.07-6.15 being recorded, indicating a high species diversity in the studied area.

Trophic structure of ichthyofauna in streams of the Contas River basin, Brazil

ABSTRACT Understand how environmental factors correlate with the trophic structure of fish communities is a fundamental step to allow designing models for the functioning of stream ecosystems and planning conservation actions. Thus, this study aims to characterize the trophic structure of fish communities of streams of the Contas River basin and evaluate the relationships between local environmental factors (stream structure and limnological variables) and trophic structure. We sample nine streams of the Upper Contas sub-basin and nine of the Gongogi sub-basin using electric fishing. We analyzed the diet of 24 species, arranged in six trophic guilds, according to stomach contents: detritivores, omnivores, insectivores, invertivores, piscivores, and algivores. The results show high proportions of detritivores (46.62%), omnivores (28.55%), and insectivores (11.8%). Invertivores were correlated to colder streams, and with little proportion of sand in the substrate. Algivores were positively related to temperature and proportion of sand in the substrate. The relationship between other guilds and the environmental factors was not significant, probably due to limitations in the number of streams in the analysis. The sub-basins did not differ regarding the trophic structure, corroborating the perception that the trophic structure is more influenced by local factors than by broader scale factors.

Long-Term Trends in the Structure and Dynamics of the Fish Communities in Buško Blato Reservoir

Abstract Buško Blato Reservoir, the third largest hydro accumulation in Europe, is situated in the south-eastern part of the karstic Livanjsko Polje Valley. This aquatic ecosystem is distinguished by a very rich ichthyofauna and the presence of four endemic fish species. Numerous studies focus on ichthyological researches of Buško Blato Reservoir. Its ichthyofauna has been exposed to changes in ecological factors, which in turn reflected on the structure and composition of fish populations. The main objective of this paper was to assess the current state and predict future trends in the ichthyofauna structure and dynamics based on the field data and comprehensive analyses of literature data. The results of the research indicated the presence of 11 fish species from four families, which is the largest number of fish species ever recorded in this ecosystem. Sander lucioperca, Lepomis gibbosus, Pseudorasbora parva and Tinca tinca were recorded for the first time in this ecosystem, while some previously recorded species were not found. The results of the analyses clearly indicate the presence of natural interspecific competition and significant level of threats to the endemic fish species caused by human activities.

Fish trophic guild responses to damming: Variations in abundance and biomass

AbstractDams and associated reservoirs cause drastic changes in the composition and structure of ichthyofauna. Therefore, functional groups within a fish assemblage may respond distinctly to such human interventions in rivers. The objective of this study was to evaluate how fluctuations in fish abundance and biomass differ among trophic guilds. Fish were sampled before and after damming four reservoirs, in their inner areas (more heavily impacted areas) and upstream (less impacted areas). To evaluate possible changes, we used a before–after and control‐impact experimental design. Fish were classified into trophic guilds through diet analysis and based on information available from the literature. Six trophic guilds were identified. The effect of periods (before and after damming) and sites (more and less impacted) on abundance and biomass differed among the trophic guilds. Highly specialized trophic guilds, such as herbivores and detritivores, were negatively affected by damming. Invertivores were negatively affected in the impacted area and increased in abundance and biomass in the less impacted sites. The findings of this study show that modifications imposed by damming are reflected in the abundance and biomass of fish trophic guilds, but the degree of such impacts vary according to characteristics of the considered trophic guild.

Damming and seasonality as modulators of fish community structure in a small tributary

AbstractRiver damming alters the physical–chemical variables of water and often causes compartmentalisation of aquatic habitats. Seasonality can add complexity to the longitudinal compartmentalisation. The spatial and temporal effects of these two phenomena on the structure of ichthyofauna from a tributary under the influence of damming were evaluated, based on the following hypotheses: (1) transition habitats have the greatest species richness; (2) community similarity decreases with increasing distance between sites; (3) conservation of free‐flowing areas upstream reservoir contributes to the maintenance of migratory species. To evaluate the effects of these two phenomena, twelve monthly fish samples (September/12 to August/13) were performed with gillnets in three sample areas distributed longitudinally in the tributary. Limnological variables were measured in the same sample areas to confirm compartmentalisation. We observed three distinct limnological compartments (lotic, transition and lentic), with increase differentiation during the rainy season. This compartmentalisation influenced fish fauna where localised communities exhibited different compositions among the three sampled habitats. During the rainy season, these differences become pronounced, with transition habitat showing greater species richness than the others. More pronounced differences in species composition and structure in extremes sampling sites were also observed. Migratory fish presented higher proportion of fish composition in lotic habitat. In conclusion, damming and seasonality acted concomitantly as modulators of fish fauna in a tributary influenced by damming. However, compartmentalisation of habitats was the primary driver of ichthyofauna community structure with the rainy season increasing differences in community composition.

Региональный подход к рыбохозяйственному нормированию содержания взвешенных веществ

The article discusses regional approach to fishery suspended sediment guidelines. The authors have proposed a system of regional normalizing with taking into account the ichthyofauna structure and background conditions to be realized at the basin level. We used the fish ranking against the sensitivity threshold by the tolerance decrease from sturgeon and catfish species (1000 mg/l) to carp (250 mg/l), perch (100 mg/l_ and salmon 910 mg/l, obvious changes with 25-35 mg/l). We have tested the system for three major territories of the Russian Federation (the Selenga River and Lena River basins and the Kamchatka Peninsula). For the Kamchatka rivers we have substantiated a critical value of the suspended matter content stable exceeding of which should lead to negative consequences for salmon species, within the concentration (S) range from 25 to 35 mg/lл; the norm’s action does not cover the rivers of the current volcanism territories. We recommend the differentiated following norm for the Selenga River basin: 25 mg/l for rivers that are habitats of salmon and grayling and 50 mg/l for rivers where whitefish species predominate. The norm for the Lena River basin is in the range from 25 to 35 mg/l for the whole river network but some downstream ranges with higher values of suspended matter content (50–100 mg/l).

Ichthyofauna species composition comparison in two estuarine lakes: Ptasi Raj and Mikoszewskie located in the Natura 2000 site "Ostoja w Ujściu Wisły"

The purpose of the following studies was to get knowledge about the composition of the ichthyofauna of two estuarine lakes: Mikoszewskie and Ptasi Raj in the Natura 2000 area “Ostoja w Ujściu Wisły” (PLH220044), located within the delta estuary created by two channels of the Vistula river: Wisła Śmiała and Przekop Wisły, reaching the Gulf of Gdańsk. Despite the research conducted on the existing flora and fauna in both nature reserves, the ichthyofauna of the lakes has not been studied so far. In order to determine as completely as possible the taxonomic composition and the quantitative structure of ichthyofauna, the different fishing gear was used: fyke nets, NORDIC multimash survey gillnets, minnow traps. In Mikoszewskie lake, there were caught a total of 774 fish representing 17 species. Higher fish number in catches, with a comparable effort applied, were recorded on the Ptasi Raj lake, where a total of 2032 fish representing 16 species were captured. Out of all 26 species found, only 9 of them were found in both water reservoirs. As it transpires from the above data, both lakes, despite seemingly similar location, due to different hydrological conditions, clearly differ in terms of the structure of inhabiting ichthyofauna. Based on the analysis of the results of conducted fish catches, it can be concluded that the ichthyofauna of the Mikoszewskie Lake is characteristic for freshwater habitats, whereas in the waters of the Ptasi Raj lake, fish populations depend on a permanent connection with the estuary waters of the Wisła Śmiała channel.

Influence of habitat connectivity and seasonality on the ichthyofauna structure of a riverine knickzone

ABSTRACT Knickzones are originated from basaltic outcroppings, present runs, riffles and pools and are highly influenced by flood pulses, which maintain their natural dynamic. However, the construction of hydroelectric power plants alters or eliminate the dynamism of this area and can affect the resident fauna that may be dependent on it. The aim of this study was to evaluate the organization of a knickzone’s ichthyofauna considering the influence of seasonality and connectivity of habitats. The study was performed in a knickzone located in the Sapucaí-Mirim River, Southeast Brazil. We sampled four rocky pools connected to the river and three isolated pools, during rainy and dry conditions. The analysis of the two factors (connectivity and seasonality) and of their interaction showed a significant influence only for seasonality on ichthyofauna structure, with higher values of abundance in the rainy season. The species that most contributed to the high dissimilarity between seasons were Knodus moenkhausii (50% of contribution) and Astyanax bockmanni (21%). The former is the most abundant species in the rainy season and the later in the dry season. The alteration between low and high water level occurs frequently in knickzones, as it is a rocky shallow platform in the middle of a river, with floods occurring seasonally or in stochastic short-term periods. This hydrological seasonal dynamic, high limnological variability and complex interactions of different habitats (pools, runs and rapids) explain the particular ichthyofauna structure in such small area. Our results also indicate the potential importance of basaltic knickzones for regional fish diversity conservation, especially due to the imminent threat by intensive hydropower reservoir construction.

Can dams affect the trophic structure of ichthyofauna? A long-term effects in the Neotropical region

ABSTRACT Dams are considered an important source of modification upon the structure of aquatic communities and their reflexes are diverse on the fish fauna. Although there are several hydroelectric power plants in Brazil, the long-term effects on feeding activity of ichthyofauna are unknown. Thus, this study aimed to investigate the long-term effects of an old reservoir (fifty years) on the trophic dynamics of fish fauna. The diet of 20 fish species was analyzed, identifying 37 food items belonging to six trophic categories, which enable to create six trophic groups. The results found here suggests that throughout the creation of a reservoir, the trophic structure of the fish assemblages tend to reach trophic homeostasis, in which the fish community will be capable of exploring the most available food resources being maintained primarily by the items placed in the categories organic matter and fragments of fish and vegetal.

Fish community response to environmental variations in an impacted Neotropical basin

AbstractFish communities’ organisation is a challenging task due to global, local and temporal variations related to biotic and abiotic factors, highlighting anthropic activities. The Verde River Basin (VRB) was chosen as a model to the fish community study due to its complexity, presenting a longitudinal gradient of degradation. The ichthyofauna and abiotic factors were sampled during twelve months in four sites. Analyses employed rarefaction curves with Hill numbers estimators and canonical correspondence analysis. The endemic Apareiodon sp. (not described), Hypostomus albopunctatus, H. strigaticeps, Oligosarcus paranensis, Neoplecostomus yapo and Trichomycterus diabolus were associated with structurally complex and well‐preserved environments. In contrary, Astyanax aff. fasciatus, Corydoras ehrhardti, Geophagus brasiliensis, H. ancistroides and Phalloceros harpagos showed tolerance to impacted environments. The methods here employed allowed to identify and explain differences in the ichthyofauna structure, distinguishing the influence of spatial, temporal and human effects on the fish communities.

Structure of the ichthyofauna of adventitious streams in the South Pantanal

ABSTRACT: The ichthyofauna of the Taquari River, one of the main tributaries of the South Pantanal, has been studied since the 1970s; however, there is a gap on the studies about the ichthyofauna present on the small adventitious streams of this highly dendritic system. These streams are small tributaries that flow directly into large rivers (mainstem), at least three orders greater in magnitude. The aim of this study was to analyze the structure of the ichthyofauna of five adventitious streams of the Upper Taquari River, South Pantanal, evaluating its temporal variation (dry and wet season) and the relation to the habitat characteristics and the conservation of the streams. Thirty-seven species were collected, from which 14 are exclusive to the Paraguay River basin, one species [Apteronotus albifrons (Linnaeus, 1766)] could represent a new record for this basin, and six species need taxonomic confirmation. The analysis indicated only the existence of spatial variation in the ichthyofauna structure of the streams sampled, with the similarity patterns related to the distance between the streams and to their conditions of conservation. The stream with greater size and preserved riparian forest was the one with the highest values of fish diversity and evenness. On the other hand, the stream with the smallest percentage of riparian forest and highest proximity to urban area presented the lowest diversity. The small size of these adventitious systems should serve as protection against large predators, which have their access to those areas hampered by their own size. Otherwise, the mainstem may also act as source of dispersal of small-bodied schooling fishes to the adventitious streams, where the greater heterogeneity of habitats and the presence of riparian vegetation should offer shelter and food supply for small species.

Ichthyofauna as an environmental quality indicator of the Bertioga Channel, São Paulo (Brazil)

Abstract The aim of this study was to investigate the ichthyofauna structure in the region of the north outfall of the Bertioga Channel (São Paulo, Brazil) and the possible effects of the environmental quality loss. The samples were collected in a monthly basis, from September to December 2005, at two oceanographic stations with an otter-trawl. The fish fauna structure was evaluated by ecological indicators and the environmental quality evaluated by the ABC analysis and the Estuarine Fish Communities Index (EFCI). A total of 1553 individuals from 50 species were sampled. Ariidae and Sciaenidae amounted to 60 % and Cathorops spixii represented 36 % of all specimens collected. The highest richness and ecological diversity were recorded in December, while the highest numerical abundance was found in October. The majority of the species were represented by juveniles. The cluster analysis and canonical correspondence analysis showed a consistent and clear difference between the sampling stations, and the abiotic factors analyzed (temperature, depth and salinity) do not seem to have influence on the community structure. The ABC analysis suggested a moderate disturbed environment and the EFCI allowed classifying the area as "poor", due to the 12 metrics analyzed, concerning the reduction of the species diversity, composition and abundance, and modifications in the nursery function and trophic integrity of the area. Future studies should focus on jointly analyze chemical indicators of water and sediment with the biological indicators, to confirm the ichthyofaunal condition of the north outfall of the Bertioga Channel.

“Porţile de Fier/Iron Gates” Gorges Area (Danube) Fish Fauna

AbstractAn important fisheries sector of the Danube, the “Iron Gates” area, was studied by famous naturalists along the history like Marsigli, Haeckel, Kner, Antipa and Bănărescu. After more than half a century after the last main publication in this area, the “Iron Gates” Danube sector suffered significant human impact, and an assessment of the fish fauna was needed. The paper summarizes the trend of fish species along the XIX to XXIst centuries, and reveals the appearance of new species. The study includes data from about 65 fish species, belonging to: Acipenseridae, Polyodontidae, Clupeidae, Salmonidae, Esocidae, Cyprinidae, Cobitidae, Siluridae, Ictaluridae, Anguillidae, Lotidae, Gasterosteidae, Syngnathidae, Centrarchidae, Percidae, Gobiidae, Odontobutidae, and Cottidae. The major hidrotechnical works along with pollution, overexploitation and poachery, induced major changes in the ichthyofauna structure.

Beaver impact on stream fish life histories: the role of landscape and local attributes

The Eurasian beaver (Castor fiber) has been reintroduced into the Carpathian Mountains and has once again become an important factor for modifying streams. Forty-three sampling sites were compared with 10 reference sites in streams not settled by beavers. Models related to the impacts of beavers on various fish life history stages and a model presenting attributes influencing the ichthyofauna structure in streams with and without beavers were generated. Significant differences in the fish species composition were found between beaver ponds versus the running sections of streams. The changes associated with pond aging caused decrease of Siberian bullhead (Cottus poecilopus) density. For brown trout (Salmo trutta), beaver ponds were the only location where large individuals were found, while the upstream parts of the beaver complexes provided spawning habitat and an area for fry growth. Common minnow (Phoxinus phoxinus) and stone loach (Barbatula barbatula) had higher density in ponds than in streams. The decisive factors for the ichthyofauna in the mountain streams settled by beavers were local attributes related to beaver activity. Our results illustrate interactions among beaver, landscape context, and fish life history in influencing the response of the stream fish assemblages to beaver recolonization. It also helps answer the question of how Eurasian beaver influence stream fish assemblages, at a much larger scale than previous studies.

The European Union Water Framework Directive and the ecological status assessment of inland waters

Upon accession to the European Union in June 2004, Poland recognized the legal jurisdiction of community laws, including that of the Water Framework Directive (Directive 2000/60/EC). This directive effected a fundamental shift, at least in member countries, in the approach to water management which included classification and assessment methods for inland waters. The WFD provides principles for assessing the status of entire aquatic ecosystems based on various biological elements or organism assemblages inhabiting waters (Soszka and Lyche Solheim 2011). The WFD sets forth provisions for the development of national assessment systems, with the novel requirement of taking into consideration reference conditions, according to which the degree of transformation in a given area of surface waters is assessed. River basin management plans created according to WFD provisions should include all surface waters within natural hydrographic units, which are divided into water segments and include surface water categories of rivers, lakes, transitional waters, coastal waters, and artificial and heavily modified water bodies. The WFD also underscores the necessity and provides general guidelines for developing the appropriate tools for conducting assessments of surface water status. The biological elements should include the following parameters and groups of organisms: composition, abundance, and biomass of phytoplankton; composition and abundance of other aquatic flora; composition and abundance of benthic invertebrates; composition, abundance, and age structure of ichthyofauna. Unfortunately, this definitive list excludes zooplankton, which has been established by science as being a significant bioindicator (e.g., Karabin 1985).