The ichthyofaunal diversity is an excellent bio indicator of the status and health of aquatic ecosystems.The present study elucidates the ichthyofaunal diversity of Sasihithlu estuary in the west coast of Karnat...The ichthyofaunal diversity is an excellent bio indicator of the status and health of aquatic ecosystems.The present study elucidates the ichthyofaunal diversity of Sasihithlu estuary in the west coast of Karnataka,India.The study was conducted from January 2019 to January 2020.Field explorations in estuary were undertaken on a monthly basis.A detailed analysis of piscine diversity revealed a total of 63 species of fresh water,estuary and marine fish belonging to 13 orders and 37 families.Perciformes was found to be a predominant order with 20 families and 31 species.Of the recorded species,one is Vulnerable and two are Near Threatened species.The greater diversity of fish was recorded during monsoon and the lesser diversity was recorded during winter.展开更多
In recent years,the taxonomy and systematics of the cartilaginous fish taxa from the Eocene La Meseta Formation of Seymour(Marambio)Island,Antarctica have been extensively discussed in a series of papers,resulting in ...In recent years,the taxonomy and systematics of the cartilaginous fish taxa from the Eocene La Meseta Formation of Seymour(Marambio)Island,Antarctica have been extensively discussed in a series of papers,resulting in a complete revision of the Antarctic Eocene ichthyofauna housed in the Vertebrate Paleontology collection of the Museo de La Plata,Argentina.This collection constitutes one of the largest and taxonomically most diverse in the world,with approximately 20000 specimens,which provides a solid database used for the analysis of qualitative and quantitative chondrichthyan taxonomic composition.The information provided herein might be useful to understand the sudden decline in chondrichthyan taxonomic diversity towards the top of La Meseta Formation as well as its potential relationship with environmental changes during the Eocene.展开更多
Present-day conditions of the Lake Kenon ecosystem are determined by a combination of natural and anthropogenic factors. We have estimated the effects of a complex of factors on the condition of the abiotic environmen...Present-day conditions of the Lake Kenon ecosystem are determined by a combination of natural and anthropogenic factors. We have estimated the effects of a complex of factors on the condition of the abiotic environment and on specific biological components in the lake ecosystem. Change in biogenic load has caused an increase in the role of phytoplankton in the general balance of organic matter during the high-water period. Charophytes are the main dominants of bottom vegetation. Anthropogenic load has caused a decrease in both fish species and fish capacity. The lake application as a water reservoir-cooler has influenced the average annual water mineralization （from 420 mg/L to 530.0 mg/L with a maximum 654 mg/L in 1993） and fluctuations in its hydrochemical composition. The present composition of the lake is sulfate-hydrocarbonate-chloride calcium-sodic-magnesium in character. S（Y44 content is twice as much as the maximum permissible concentration in fishery waters. Water drainage from an ash disposal area to the lake has caused an increase in chemical-element concentrations including the heavy metals. Hg concentration in Perca fluviatilis muscles is 0.5 9g/g dry wt. Thus, understanding directions in the ecosystem of the water reservoir-cooler under changing hydrological conditions will let us forecast the consequences of new combined heat and power plant operation.展开更多
The Capim River drainage should be considered small and thin by comparison with large Amazonian rivers. It rises by confluence of the Surubiú and Ararandeua rivers near 400 m high and their headwaters would be co...The Capim River drainage should be considered small and thin by comparison with large Amazonian rivers. It rises by confluence of the Surubiú and Ararandeua rivers near 400 m high and their headwaters would be comfortably included in the Dry Emerged Lowland (terra firme) forest area of Sternberg’s Amazonian concept. Because of this reason the freshwater fish fauna of Capim River is comprised mainly by Amazonian fish families found in tributaries also with origin in terra firme areas. The ichthyofauna from the main channel of the poorly sampled Capim River, in the stretch between its confluence with Tauarí River and its mouth at Guamá River, is herein reported by way of rapid assessment. Also broad comparisons were made among freshwater fishes of the Capim with that from Tocantins and Guamá rivers. Two rapid access research surveys of collecting ichthyological material were performed in dry and humid periods of the year 1998 comprising the regional hydrologic cycle. The ichthyological diversity showed by the 461 studied specimens includes 79 species probably derived from Guamá and Tocantins rivers. These species are distributed between two situations: 1) downstream Capim River, at confluence with Guamá River, where is under tidal waters influence and periodically flooded, and 2) upriver Capim that is less humid and with water rapids, independent from sea hydrologic influence. This fish fauna includes local species common at high areas of the Amazonian Dry Emerged Lowland that are in part shared with that from Tocantins River. In view of these observations, we assume that the Capim River freshwater ichthyofauna may reflect diverse origin from the simple transfer of populations from Guamá River, but originate through a more complex process including the past ichthyofauna of the earlier drainages of terra firme forest and their reorganization.展开更多
Some physicochemical parameters like temperature, transparency, dissolved solid, suspended materials, turbidity, conductivity, pH, total alkalinity, dissolved oxygen, nitrate, phosphate and salinity of water samples c...Some physicochemical parameters like temperature, transparency, dissolved solid, suspended materials, turbidity, conductivity, pH, total alkalinity, dissolved oxygen, nitrate, phosphate and salinity of water samples collected at Lekki Lagoon from November 2010 to September 2012 were evaluated. Fifteen locations were selected for water sampling according to the activities that took place in the lagoon. Physical water quality parameters such as temperature, transparency, total dissolved solids and total suspended solid showed strong seasonal and spatial fluctuation. Parameters like conductivity, pH and total alkalinity had relatively constant values among stations though they varied seasonally. Dissolved oxygen, nitrate and phosphate values were within permissible range for fish. Higher salinity values were recorded in wet seasons than dry seasons suggesting that salinity variation at Lekki Lagoon was due to salt incursion from the adjourning Lagos Lagoon and Mahin Creek during rainy season rather than evaporation factor. Salinity range of 1.70 - 6.00 psu recorded in this study also shows that Lekki Lagoon is tending towards brackish and this may affect the ichthyofauna composition of the lagoon.展开更多
Reliable and basic information on fish are required for the sustainable management of a fishery. For this reason, the fish fauna of the future reservoir of Ouessa in the low section of the Mouhoun River, Burkina Faso ...Reliable and basic information on fish are required for the sustainable management of a fishery. For this reason, the fish fauna of the future reservoir of Ouessa in the low section of the Mouhoun River, Burkina Faso is studied. In order to describe the fish community, the fish were sampled in March 2020 thanks to cast nets and gill nets. They were sorted into species and each fish was weighted at the nearest 0.1 g and its total length measured at the nearest mm. The landings of commercial fishermen were also observed. In total, 1059 fishes were collected and grouped into 42 species, 27 generas and 16 families. The dominant species were <i>Synodontis nigrita</i>,<i> Synodontis schall</i>,<i> Marcusenius senegalensis</i>, <i>Schilbe intermedius</i>, <i>Brycinus nurse </i>and <i>Alestes baremoze</i>. However, the compilation of diverse sources suggests the presence of nearly 70 species. The index of Shannon-Weaver (3.97), the values of the condition factor, the fish size and the presence of intolerant species indicate the relatively good conditions of the aquatic ecosystem. Among the 24 dominant species, 54% have a positive allometric growth, 42% a negative allometric growth and 0.04 an isometric growth. This study builds the basis of sustainable management of the future reservoir of Ouessa that is planned to be the largest one of the country (40,000 ha large).展开更多
Inland waters are highly vulnerable to the introduction and spread of non-native species,due to heavy human use of aquatic ecosystems and the natural linkages among streams and lakes.This is particularly noticeable in...Inland waters are highly vulnerable to the introduction and spread of non-native species,due to heavy human use of aquatic ecosystems and the natural linkages among streams and lakes.This is particularly noticeable in freshwater fish communities.To better evaluate how these communities are affected by non-native species introductions,we conducted a fine-scale analysis of the changes in Italian freshwater fish assemblages after species introduction.For this analysis,we collected information on fish species present in 44 basins.The present Italian freshwater fish fauna is composed of 48 native and 41 established introduced species,while a further 15 introduced species have been reported but are not yet considered naturalized.The changes in the fish assemblages mostly took place in the past 2 centuries and have increased recently,with nearly 60%of the species introduced in the past 3 decades.The number of species introduced per basin ranged from 0 to 35(mean 10.85±7.77 species/basin),and in 10 basins the number of species introduced is now equal to or even higher than the number of native species.In the past,introduced species mainly originated from America,but over the past three decades,an increase of introductions from other parts of Europe and Asia has been recorded.Our results show that basins already rich in native species tend to become even richer as a consequence of the establishment of introduced species.This confirms the trend toward a biotic homogenization of ecosystems even at a local scale,due to an increase in the human-mediated spread of generalist species.展开更多
文摘The ichthyofaunal diversity is an excellent bio indicator of the status and health of aquatic ecosystems.The present study elucidates the ichthyofaunal diversity of Sasihithlu estuary in the west coast of Karnataka,India.The study was conducted from January 2019 to January 2020.Field explorations in estuary were undertaken on a monthly basis.A detailed analysis of piscine diversity revealed a total of 63 species of fresh water,estuary and marine fish belonging to 13 orders and 37 families.Perciformes was found to be a predominant order with 20 families and 31 species.Of the recorded species,one is Vulnerable and two are Near Threatened species.The greater diversity of fish was recorded during monsoon and the lesser diversity was recorded during winter.
基金Thanks to the Agencia Nacional de Promoción Científica y Tecnológica for financial support trough PICT 2017-0607(to MR),PICT 2019-02419(to SGC).
文摘In recent years,the taxonomy and systematics of the cartilaginous fish taxa from the Eocene La Meseta Formation of Seymour(Marambio)Island,Antarctica have been extensively discussed in a series of papers,resulting in a complete revision of the Antarctic Eocene ichthyofauna housed in the Vertebrate Paleontology collection of the Museo de La Plata,Argentina.This collection constitutes one of the largest and taxonomically most diverse in the world,with approximately 20000 specimens,which provides a solid database used for the analysis of qualitative and quantitative chondrichthyan taxonomic composition.The information provided herein might be useful to understand the sudden decline in chondrichthyan taxonomic diversity towards the top of La Meseta Formation as well as its potential relationship with environmental changes during the Eocene.
基金Supported by the RFBR No.14-05-98013"Siberia"(2014–2016)the Project of SB of the RAS VIII.79.1.2."Dynamics of natural and natural-anthropogenic systems in the conditions of climate change and anthropogenic pressures(on the example of Transbaikalia)"(2012–2017)
文摘Present-day conditions of the Lake Kenon ecosystem are determined by a combination of natural and anthropogenic factors. We have estimated the effects of a complex of factors on the condition of the abiotic environment and on specific biological components in the lake ecosystem. Change in biogenic load has caused an increase in the role of phytoplankton in the general balance of organic matter during the high-water period. Charophytes are the main dominants of bottom vegetation. Anthropogenic load has caused a decrease in both fish species and fish capacity. The lake application as a water reservoir-cooler has influenced the average annual water mineralization （from 420 mg/L to 530.0 mg/L with a maximum 654 mg/L in 1993） and fluctuations in its hydrochemical composition. The present composition of the lake is sulfate-hydrocarbonate-chloride calcium-sodic-magnesium in character. S（Y44 content is twice as much as the maximum permissible concentration in fishery waters. Water drainage from an ash disposal area to the lake has caused an increase in chemical-element concentrations including the heavy metals. Hg concentration in Perca fluviatilis muscles is 0.5 9g/g dry wt. Thus, understanding directions in the ecosystem of the water reservoir-cooler under changing hydrological conditions will let us forecast the consequences of new combined heat and power plant operation.
文摘The Capim River drainage should be considered small and thin by comparison with large Amazonian rivers. It rises by confluence of the Surubiú and Ararandeua rivers near 400 m high and their headwaters would be comfortably included in the Dry Emerged Lowland (terra firme) forest area of Sternberg’s Amazonian concept. Because of this reason the freshwater fish fauna of Capim River is comprised mainly by Amazonian fish families found in tributaries also with origin in terra firme areas. The ichthyofauna from the main channel of the poorly sampled Capim River, in the stretch between its confluence with Tauarí River and its mouth at Guamá River, is herein reported by way of rapid assessment. Also broad comparisons were made among freshwater fishes of the Capim with that from Tocantins and Guamá rivers. Two rapid access research surveys of collecting ichthyological material were performed in dry and humid periods of the year 1998 comprising the regional hydrologic cycle. The ichthyological diversity showed by the 461 studied specimens includes 79 species probably derived from Guamá and Tocantins rivers. These species are distributed between two situations: 1) downstream Capim River, at confluence with Guamá River, where is under tidal waters influence and periodically flooded, and 2) upriver Capim that is less humid and with water rapids, independent from sea hydrologic influence. This fish fauna includes local species common at high areas of the Amazonian Dry Emerged Lowland that are in part shared with that from Tocantins River. In view of these observations, we assume that the Capim River freshwater ichthyofauna may reflect diverse origin from the simple transfer of populations from Guamá River, but originate through a more complex process including the past ichthyofauna of the earlier drainages of terra firme forest and their reorganization.
文摘Some physicochemical parameters like temperature, transparency, dissolved solid, suspended materials, turbidity, conductivity, pH, total alkalinity, dissolved oxygen, nitrate, phosphate and salinity of water samples collected at Lekki Lagoon from November 2010 to September 2012 were evaluated. Fifteen locations were selected for water sampling according to the activities that took place in the lagoon. Physical water quality parameters such as temperature, transparency, total dissolved solids and total suspended solid showed strong seasonal and spatial fluctuation. Parameters like conductivity, pH and total alkalinity had relatively constant values among stations though they varied seasonally. Dissolved oxygen, nitrate and phosphate values were within permissible range for fish. Higher salinity values were recorded in wet seasons than dry seasons suggesting that salinity variation at Lekki Lagoon was due to salt incursion from the adjourning Lagos Lagoon and Mahin Creek during rainy season rather than evaporation factor. Salinity range of 1.70 - 6.00 psu recorded in this study also shows that Lekki Lagoon is tending towards brackish and this may affect the ichthyofauna composition of the lagoon.
文摘Reliable and basic information on fish are required for the sustainable management of a fishery. For this reason, the fish fauna of the future reservoir of Ouessa in the low section of the Mouhoun River, Burkina Faso is studied. In order to describe the fish community, the fish were sampled in March 2020 thanks to cast nets and gill nets. They were sorted into species and each fish was weighted at the nearest 0.1 g and its total length measured at the nearest mm. The landings of commercial fishermen were also observed. In total, 1059 fishes were collected and grouped into 42 species, 27 generas and 16 families. The dominant species were <i>Synodontis nigrita</i>,<i> Synodontis schall</i>,<i> Marcusenius senegalensis</i>, <i>Schilbe intermedius</i>, <i>Brycinus nurse </i>and <i>Alestes baremoze</i>. However, the compilation of diverse sources suggests the presence of nearly 70 species. The index of Shannon-Weaver (3.97), the values of the condition factor, the fish size and the presence of intolerant species indicate the relatively good conditions of the aquatic ecosystem. Among the 24 dominant species, 54% have a positive allometric growth, 42% a negative allometric growth and 0.04 an isometric growth. This study builds the basis of sustainable management of the future reservoir of Ouessa that is planned to be the largest one of the country (40,000 ha large).
文摘Inland waters are highly vulnerable to the introduction and spread of non-native species,due to heavy human use of aquatic ecosystems and the natural linkages among streams and lakes.This is particularly noticeable in freshwater fish communities.To better evaluate how these communities are affected by non-native species introductions,we conducted a fine-scale analysis of the changes in Italian freshwater fish assemblages after species introduction.For this analysis,we collected information on fish species present in 44 basins.The present Italian freshwater fish fauna is composed of 48 native and 41 established introduced species,while a further 15 introduced species have been reported but are not yet considered naturalized.The changes in the fish assemblages mostly took place in the past 2 centuries and have increased recently,with nearly 60%of the species introduced in the past 3 decades.The number of species introduced per basin ranged from 0 to 35(mean 10.85±7.77 species/basin),and in 10 basins the number of species introduced is now equal to or even higher than the number of native species.In the past,introduced species mainly originated from America,but over the past three decades,an increase of introductions from other parts of Europe and Asia has been recorded.Our results show that basins already rich in native species tend to become even richer as a consequence of the establishment of introduced species.This confirms the trend toward a biotic homogenization of ecosystems even at a local scale,due to an increase in the human-mediated spread of generalist species.
