The assessment of ecological status for running waters is one of the major issues within an integrated river basin management and plays a key role with respect to the implementation of the European Water Frame- work D...The assessment of ecological status for running waters is one of the major issues within an integrated river basin management and plays a key role with respect to the implementation of the European Water Frame- work Directive (WFD).One of the tools supporting the development of sustainable river management is physi- cal habitat modeling,e.g.,for fish,because fish population are one of the most important indicators for the e- colngical integrity of rivers.Within physical habitat models hydromorphological ...展开更多
Fisheries in Lake Victoria have been threatened by declining fish stocks and diversity, environmental degradation due to increased input of pollutants, industrial and municipal waste, overfishing and use of unapproved...Fisheries in Lake Victoria have been threatened by declining fish stocks and diversity, environmental degradation due to increased input of pollutants, industrial and municipal waste, overfishing and use of unapproved fishing <span style="font-family:Verdana;">methods, infestation by aquatic weeds especially water hyacinth, de-oxygenation</span><span style="font-family:Verdana;"> and a reduction in the quantity and quality of water. Remote sensing and GIS are essential tools in detection of fishing grounds which is important in providing fish sustainability for human beings and allows fishing grounds detection at minimal cost and optimizes effort. This research tends to identify the most favorable both environmentally and ecologically satisfactory factors which favor fish breeding and growth. The main aim of the study was to identify habitat variables that promote fish breeding and growth to maturity including the extraction of environmental variables from Landsat 8 images for the study period and using suitability index derived from fishery data. The study concentrated on establishing suitability ratings in different parts of Lake Victoria using lake surface temperature and chlorophyll-a levels. The study was conducted for months;January, May and December 2019 on Lake Victoria (limited by the availability of recent data). The factors were analysed and the favorable regions mapped satisfying the conditions for fish breeding. The output obtained illustrated the availability of suitable and habitable zones within the lake using satellite imagery and the suitability index. The fish catch data and satellite derived variables were used to determine habitat suitability indices for fish during January, May and December 2019. More than 90% of the total catch was found to come from the areas with sea surface temperature of 23.0˚C - 28.3˚C and chlorophyll-</span><span style="font-family:Verdana;">a </span><span style="font-family:Verdana;">concentration between 0.72 - 1.31 mg/m</span><sup><span style="font-family:Verdana;vertical-align:super;">3</span></sup><span style="font-family:Verdana;">. The catch data was used to validate the images. This study indicated the capability of High Satellite Resolution Imageries (HSI) as a tool to map the potential fishing grounds of fish species in Lake Victoria. The variables were affected by climatic change factors like rainfall and temperature of the lake basin and other human activities around the lake and also the species ecosystem like competition or predation.</span>展开更多
The spatial distribution and community structure of the fishes were studied at different depths and sites along the Jordanian coast in seagrass habitat. A total of 37,034 fishes were counted representing 132 species b...The spatial distribution and community structure of the fishes were studied at different depths and sites along the Jordanian coast in seagrass habitat. A total of 37,034 fishes were counted representing 132 species belonging to 35 families observed during visual census in three sites (average of 4741.6 fish per transect). Out of the 132 species encountered, 5 species of them including Neopomacentrus miryae Lethrinus borbonicus, Pseudanthias squamipinnis, Lethrinus variegatus, Siganus rivulatus accounted for 57.7% of all individuals. Fishes were most abundant and significantly higher at 12 m depths (mean N = 2889.6) in comparison with shallow 6m depth (mean = 1225.3 with (p = 0.0218). This may be attributed to many plank-tivorous fishes that inhabit this depth such as P. squampinnis, Paracheilinus octotaenia, Chromis pelloura, Decapterus macarellus, and Cirrhilabrus rubriventralis probably with high abundance of plankton at 12 m depth than 6 m. The number of species was significantly higher in Phosphate Loading Berth (PLB;mean S = 54.7) than in Hotels area site (HA;mean S = 12.8) with (p = 0.0002) and Tala Bay site (TB;mean S = 31) with (p = 0.0484). This may be due to higher hard coral cover at Phophate Loading Berth.展开更多
Fish communities in a (third-order) intertidal creek in Dongtan marsh in the Changjiang (Yangtze) River estuary were investigated seasonally for one year.A total of 1 996 fish specimens (10 967.8 g) comprising 26 spec...Fish communities in a (third-order) intertidal creek in Dongtan marsh in the Changjiang (Yangtze) River estuary were investigated seasonally for one year.A total of 1 996 fish specimens (10 967.8 g) comprising 26 species and 15 families were collected.Abundances of fish communities in the intertidal salt marsh creek were primarily dominated by Boleophthalmus pectinirostris (19.8%),Collichthys lucidus (18.6%),Periophthalmus magnuspinnatus (18.2%),Liza haematocheilus (17.9%),and secondarily by Mugilogobius abei (8.5%),L.carinatus (7.2%),Odontamblyopus lacepedii (4.3%),and Acanthogobius ommaturus (3.9%);another 18 species were present only occasionally.Non-MDS ordination and SIMPER analysis indicated that there were two fish communities in the intertidal salt marsh creek.In spring,the communities were dominated by B.pectinirostris,P.magnuspinnatus,C.lucidus and M.abei;in summer,autumn,and winter by L.haematocheilus,L.carinatus,A.ommaturus and O.lacepedii.Some species showed strong habitat selection;L.carinatus and P.magnuspinnatus were distributed mainly in the upper and middle creek,while B.pectinirostris,M.abei and O.lacepedii inhabited the middle and lower creek.The study indicated that the salt marshes of the Changjiang River estuary are an important nursery and feeding habitat for many fishes and should be protected.展开更多
Spatial distribution and abundance of small fishes were studied in autumn 2007 in the Xiaosihai Lake, a shallow lake along the middle reach of the Changjiang (Yangtze) River. Based on the plant cover, the lake was div...Spatial distribution and abundance of small fishes were studied in autumn 2007 in the Xiaosihai Lake, a shallow lake along the middle reach of the Changjiang (Yangtze) River. Based on the plant cover, the lake was divided into three major habitats: Myriophyllum spicatum habitat (MS habitat), Trapa bispinosa habitat (TB habitat), and non-vegetation habitat (NV habitat). A modified pop-net was used for quantitative sampling of small fishes in the three habitats, and the Zippin’s removal method was used for estimating densities of the small fishes. A total of 13 species belonging to 5 families were collected, with 11 species in MS habitat, 7 species in TB habitat, and 5 species in NV habitat. Habitat type had significant effect on the spatial distribution of small fishes. The Shannon-Wiener diversity index in the MS, TB and NV habitats were 1.28, 0.56 and 0.54, respectively. The total density and biomass of small fishes were significantly higher in the MS habitat (13.68 ind/m2 and 4.44 g/m2) than in the TB habitat (1.41 ind/m2 and 0.54 g/m2) and the NV habitat (1.08 ind/m2 and 0.40 g/m2), and were not significantly different between the TB habitat and the NV habitat. Water depth had no significant effect on spatial distribution of the small fishes. It was suggested that vegetation type played an important role in habitat selectivity of small fishes, and the presence of submersed vegetation should be of significance in the conservation of small fish diversity.展开更多
This study sought to review whether large-scale experimentation can apply to actual rivers concerning the effect of topographical change by scour in the downstream area of natural-type low drop structures on the fish ...This study sought to review whether large-scale experimentation can apply to actual rivers concerning the effect of topographical change by scour in the downstream area of natural-type low drop structures on the fish habitat. The large-scale applicability experiment performed in this study installed low drop structures as the study object within the experiment channel and precisely surveyed topography in the downstream area of drop structures along with the hydraulic amount including water level and flow velocity under certain flow conditions. Based on topographical data acquired through the survey after the experiment ended, this study reviewed the change of suitability index and difference of weighted usable area by performing 2D habitat simulation. Ultimately, through the habitat simulation results in cases of considering and not considering scour in the downstream area of drop structures, this study analyzed the effects of topographical change in actual rivers on the habitat.展开更多
Dam removal is becoming an effective approach for aquatic biodiversity restoration in damming river in order to balance the aquatic ecosystem conservation with large-scale cascade damming. However, the effects of dam ...Dam removal is becoming an effective approach for aquatic biodiversity restoration in damming river in order to balance the aquatic ecosystem conservation with large-scale cascade damming. However, the effects of dam removal on fish communities in Asian mountainous rivers, which are dominated by Cypriniformes fishes, are still not well known. To determine whether dam removal on a mountainous river benefit restoration of fish diversity, we investigated the response of fish assemblage to dam removal using a before-after-control-impact design in two tributaries of the Lancang River(dam removal river: the Jidu River, and control river: the Fengdian River). Fish surveys were conducted one year prior to dam removal(2012) and three years(2013–2015) following dam removal. We observed rapidly and notably spatio-temporal changes in fish biodiversity metrics and assemblage structure, occurring in the Jidu River within the first year after dam removal. Overall, fish species richness, density and Shannon-Wiener diversity all increased immediately in above-and below-dam sites, and maintained a stable level in subsequent years, compared to unchanged situation in the control river. All sites in the Jidu River experienced shifts in fish composition after dam removal, with the greatest temporal changes occurred in sites below-and above-the former dam, resulting in a temporal homogenization tendency in the dam removed river. These findings suggest that dam removal can benefit the recovery of habitat conditions and fish community in Asian mountainous rivers, but the results should be further evaluated when apply to other dammed rivers since the dam age, fluvial geomorphology and situation of source populations could all affect the responses of fish assemblages.展开更多
In this review, I explore the effects of both social organization and the physical environment, specifically habitatcomplexity, on the brains and behavior of highly visual African cichlid fishes, drawing on examples f...In this review, I explore the effects of both social organization and the physical environment, specifically habitatcomplexity, on the brains and behavior of highly visual African cichlid fishes, drawing on examples from primates and birdswhere appropriate. In closely related fishes from the monophyletic Ectodinii clade of Lake Tanganyika, both forces influencecichlid brains and behavior. Considering social influences first, visual acuity differs with respect to social organization (monogamyversus polygyny). Both the telencephalon and amygdalar homologue, area Dm, are larger in monogamous species. Monogamousspecies are found to have more vasotocin-immunoreactive cells in the preoptic area of the brain. Habitat complexityalso influences brain and behavior in these fishes. Total brain size, telencephalic and cerebellar size are positively correlated withhabitat complexity. Visual acuity and spatial memory are enhanced in cichlids living in more complex environments. Howeverhabitat complexity and social forces affect cichlid brains differently. Taken together, our field data and plasticity data suggest thatsome of the species-specific neural effects of habitat complexity could be the consequence of the corresponding social correlates.Environmental forces, however, exert a broader effect on brain structures than social ones do, suggesting allometric expansion ofthe brain structures in concert with brain size and/or co-evolution of these展开更多
The eastern fall cohort of the neon flying squid, Ommastrephes bartramii, has been commercially exploited by the Chinese squid jigging fleet in the central North Pacific Ocean since the late 1990s. To understand and i...The eastern fall cohort of the neon flying squid, Ommastrephes bartramii, has been commercially exploited by the Chinese squid jigging fleet in the central North Pacific Ocean since the late 1990s. To understand and identify their optimal habitat, we have developed a habitat suitability index (HSI) model using two potential important environmental variables - sea surface temperature (SST) and sea surface height anomaly (SSHA) - and fishery data from the main fishing ground (165°-180°E) during June and July of 1999-2003. A geometric mean model (GMM), minimum model (MM) and arithmetic weighted model (AWM) with different weights were compared and the best HSI model was selected using Akaike's information criterion (AIC). The performance of the developed HSI model was evaluated using fishery data for 2004. This study suggests that the highest catch per unit effort (CPUE) and fishing effort are closely related to SST and SSHA. The best SST- and SSHA-based suitability index (SI) regression models were SISST-based = 0.7SIeffort-SST + 0.3 SICPUE-SST, and SISSHA-based = 0.5SIeffort-SSHA + 0.5SICPUE-SSHA, respectively, showing that fishing effort is more important than CPUE in the estimation of SI. The best HSI model was the AWM, defined as HSI=0.3SISST-based+ 0.7SISSHA-based, indicating that SSHA is more important than SST in estimating the HSI of squid. In 2004, monthly HSI values greater than 0.6 coincided with the distribution of productive fishing ground and high CPUE in June and July, suggesting that the models perform well. The proposed model provides an important tool in our efforts to develop forecasting capacity of squid spatial dynamics.展开更多
文摘The assessment of ecological status for running waters is one of the major issues within an integrated river basin management and plays a key role with respect to the implementation of the European Water Frame- work Directive (WFD).One of the tools supporting the development of sustainable river management is physi- cal habitat modeling,e.g.,for fish,because fish population are one of the most important indicators for the e- colngical integrity of rivers.Within physical habitat models hydromorphological ...
文摘Fisheries in Lake Victoria have been threatened by declining fish stocks and diversity, environmental degradation due to increased input of pollutants, industrial and municipal waste, overfishing and use of unapproved fishing <span style="font-family:Verdana;">methods, infestation by aquatic weeds especially water hyacinth, de-oxygenation</span><span style="font-family:Verdana;"> and a reduction in the quantity and quality of water. Remote sensing and GIS are essential tools in detection of fishing grounds which is important in providing fish sustainability for human beings and allows fishing grounds detection at minimal cost and optimizes effort. This research tends to identify the most favorable both environmentally and ecologically satisfactory factors which favor fish breeding and growth. The main aim of the study was to identify habitat variables that promote fish breeding and growth to maturity including the extraction of environmental variables from Landsat 8 images for the study period and using suitability index derived from fishery data. The study concentrated on establishing suitability ratings in different parts of Lake Victoria using lake surface temperature and chlorophyll-a levels. The study was conducted for months;January, May and December 2019 on Lake Victoria (limited by the availability of recent data). The factors were analysed and the favorable regions mapped satisfying the conditions for fish breeding. The output obtained illustrated the availability of suitable and habitable zones within the lake using satellite imagery and the suitability index. The fish catch data and satellite derived variables were used to determine habitat suitability indices for fish during January, May and December 2019. More than 90% of the total catch was found to come from the areas with sea surface temperature of 23.0˚C - 28.3˚C and chlorophyll-</span><span style="font-family:Verdana;">a </span><span style="font-family:Verdana;">concentration between 0.72 - 1.31 mg/m</span><sup><span style="font-family:Verdana;vertical-align:super;">3</span></sup><span style="font-family:Verdana;">. The catch data was used to validate the images. This study indicated the capability of High Satellite Resolution Imageries (HSI) as a tool to map the potential fishing grounds of fish species in Lake Victoria. The variables were affected by climatic change factors like rainfall and temperature of the lake basin and other human activities around the lake and also the species ecosystem like competition or predation.</span>
文摘The spatial distribution and community structure of the fishes were studied at different depths and sites along the Jordanian coast in seagrass habitat. A total of 37,034 fishes were counted representing 132 species belonging to 35 families observed during visual census in three sites (average of 4741.6 fish per transect). Out of the 132 species encountered, 5 species of them including Neopomacentrus miryae Lethrinus borbonicus, Pseudanthias squamipinnis, Lethrinus variegatus, Siganus rivulatus accounted for 57.7% of all individuals. Fishes were most abundant and significantly higher at 12 m depths (mean N = 2889.6) in comparison with shallow 6m depth (mean = 1225.3 with (p = 0.0218). This may be attributed to many plank-tivorous fishes that inhabit this depth such as P. squampinnis, Paracheilinus octotaenia, Chromis pelloura, Decapterus macarellus, and Cirrhilabrus rubriventralis probably with high abundance of plankton at 12 m depth than 6 m. The number of species was significantly higher in Phosphate Loading Berth (PLB;mean S = 54.7) than in Hotels area site (HA;mean S = 12.8) with (p = 0.0002) and Tala Bay site (TB;mean S = 31) with (p = 0.0484). This may be due to higher hard coral cover at Phophate Loading Berth.
基金Supported by Special Research Fund for the National Non-profit Institutes (East China Sea Fisheries Research Institute) (No.2007M03) and Administration Bureau of Virescence of Shanghai Municipality
文摘Fish communities in a (third-order) intertidal creek in Dongtan marsh in the Changjiang (Yangtze) River estuary were investigated seasonally for one year.A total of 1 996 fish specimens (10 967.8 g) comprising 26 species and 15 families were collected.Abundances of fish communities in the intertidal salt marsh creek were primarily dominated by Boleophthalmus pectinirostris (19.8%),Collichthys lucidus (18.6%),Periophthalmus magnuspinnatus (18.2%),Liza haematocheilus (17.9%),and secondarily by Mugilogobius abei (8.5%),L.carinatus (7.2%),Odontamblyopus lacepedii (4.3%),and Acanthogobius ommaturus (3.9%);another 18 species were present only occasionally.Non-MDS ordination and SIMPER analysis indicated that there were two fish communities in the intertidal salt marsh creek.In spring,the communities were dominated by B.pectinirostris,P.magnuspinnatus,C.lucidus and M.abei;in summer,autumn,and winter by L.haematocheilus,L.carinatus,A.ommaturus and O.lacepedii.Some species showed strong habitat selection;L.carinatus and P.magnuspinnatus were distributed mainly in the upper and middle creek,while B.pectinirostris,M.abei and O.lacepedii inhabited the middle and lower creek.The study indicated that the salt marshes of the Changjiang River estuary are an important nursery and feeding habitat for many fishes and should be protected.
基金Supported by the National Natural Science Foundation of China (Nos. 30571440, 30830025)The National Key Technology R&D Program (No. 2007BAD37B03)the National Basic Research Program of China (973 Program) (No. 2007CB109205)
文摘Spatial distribution and abundance of small fishes were studied in autumn 2007 in the Xiaosihai Lake, a shallow lake along the middle reach of the Changjiang (Yangtze) River. Based on the plant cover, the lake was divided into three major habitats: Myriophyllum spicatum habitat (MS habitat), Trapa bispinosa habitat (TB habitat), and non-vegetation habitat (NV habitat). A modified pop-net was used for quantitative sampling of small fishes in the three habitats, and the Zippin’s removal method was used for estimating densities of the small fishes. A total of 13 species belonging to 5 families were collected, with 11 species in MS habitat, 7 species in TB habitat, and 5 species in NV habitat. Habitat type had significant effect on the spatial distribution of small fishes. The Shannon-Wiener diversity index in the MS, TB and NV habitats were 1.28, 0.56 and 0.54, respectively. The total density and biomass of small fishes were significantly higher in the MS habitat (13.68 ind/m2 and 4.44 g/m2) than in the TB habitat (1.41 ind/m2 and 0.54 g/m2) and the NV habitat (1.08 ind/m2 and 0.40 g/m2), and were not significantly different between the TB habitat and the NV habitat. Water depth had no significant effect on spatial distribution of the small fishes. It was suggested that vegetation type played an important role in habitat selectivity of small fishes, and the presence of submersed vegetation should be of significance in the conservation of small fish diversity.
文摘This study sought to review whether large-scale experimentation can apply to actual rivers concerning the effect of topographical change by scour in the downstream area of natural-type low drop structures on the fish habitat. The large-scale applicability experiment performed in this study installed low drop structures as the study object within the experiment channel and precisely surveyed topography in the downstream area of drop structures along with the hydraulic amount including water level and flow velocity under certain flow conditions. Based on topographical data acquired through the survey after the experiment ended, this study reviewed the change of suitability index and difference of weighted usable area by performing 2D habitat simulation. Ultimately, through the habitat simulation results in cases of considering and not considering scour in the downstream area of drop structures, this study analyzed the effects of topographical change in actual rivers on the habitat.
基金the National Natural Science Foundation of China(No.41501574)the National Key Research and Development Program of China(No.2016YFA0601601)+1 种基金the Yunnan Applied Basic Research Projects(No.2016FB079)the National Science and Technology Support Program of China(No.2013BAB06B03)
文摘Dam removal is becoming an effective approach for aquatic biodiversity restoration in damming river in order to balance the aquatic ecosystem conservation with large-scale cascade damming. However, the effects of dam removal on fish communities in Asian mountainous rivers, which are dominated by Cypriniformes fishes, are still not well known. To determine whether dam removal on a mountainous river benefit restoration of fish diversity, we investigated the response of fish assemblage to dam removal using a before-after-control-impact design in two tributaries of the Lancang River(dam removal river: the Jidu River, and control river: the Fengdian River). Fish surveys were conducted one year prior to dam removal(2012) and three years(2013–2015) following dam removal. We observed rapidly and notably spatio-temporal changes in fish biodiversity metrics and assemblage structure, occurring in the Jidu River within the first year after dam removal. Overall, fish species richness, density and Shannon-Wiener diversity all increased immediately in above-and below-dam sites, and maintained a stable level in subsequent years, compared to unchanged situation in the control river. All sites in the Jidu River experienced shifts in fish composition after dam removal, with the greatest temporal changes occurred in sites below-and above-the former dam, resulting in a temporal homogenization tendency in the dam removed river. These findings suggest that dam removal can benefit the recovery of habitat conditions and fish community in Asian mountainous rivers, but the results should be further evaluated when apply to other dammed rivers since the dam age, fluvial geomorphology and situation of source populations could all affect the responses of fish assemblages.
基金supported by NSF grants IBN-02180005 to Caroly Shumway (CAS) and IBN-021795 to Hans Hofmann (HAH)a German-American Research Networking Program grant to CAS and HAH+1 种基金the New England Aquarium to CASthe Bauer Center for Genomics Research to HAH
文摘In this review, I explore the effects of both social organization and the physical environment, specifically habitatcomplexity, on the brains and behavior of highly visual African cichlid fishes, drawing on examples from primates and birdswhere appropriate. In closely related fishes from the monophyletic Ectodinii clade of Lake Tanganyika, both forces influencecichlid brains and behavior. Considering social influences first, visual acuity differs with respect to social organization (monogamyversus polygyny). Both the telencephalon and amygdalar homologue, area Dm, are larger in monogamous species. Monogamousspecies are found to have more vasotocin-immunoreactive cells in the preoptic area of the brain. Habitat complexityalso influences brain and behavior in these fishes. Total brain size, telencephalic and cerebellar size are positively correlated withhabitat complexity. Visual acuity and spatial memory are enhanced in cichlids living in more complex environments. Howeverhabitat complexity and social forces affect cichlid brains differently. Taken together, our field data and plasticity data suggest thatsome of the species-specific neural effects of habitat complexity could be the consequence of the corresponding social correlates.Environmental forces, however, exert a broader effect on brain structures than social ones do, suggesting allometric expansion ofthe brain structures in concert with brain size and/or co-evolution of these
基金Supported by the PhD Programs Foundation of Ministry of Education of China (No. 20093104110002)the National High Technology Research and Development Program of China (863 Program) (Nos. 2007AA092201, 2007AA092202)+2 种基金the National Natural Science Foundation (No. NSFC40876090)the Shanghai Leading Academic Discipline Project (No. S30702)Y. Chen's involvement in the project was partially supported by the Shanghai Dongfang Scholar Program
文摘The eastern fall cohort of the neon flying squid, Ommastrephes bartramii, has been commercially exploited by the Chinese squid jigging fleet in the central North Pacific Ocean since the late 1990s. To understand and identify their optimal habitat, we have developed a habitat suitability index (HSI) model using two potential important environmental variables - sea surface temperature (SST) and sea surface height anomaly (SSHA) - and fishery data from the main fishing ground (165°-180°E) during June and July of 1999-2003. A geometric mean model (GMM), minimum model (MM) and arithmetic weighted model (AWM) with different weights were compared and the best HSI model was selected using Akaike's information criterion (AIC). The performance of the developed HSI model was evaluated using fishery data for 2004. This study suggests that the highest catch per unit effort (CPUE) and fishing effort are closely related to SST and SSHA. The best SST- and SSHA-based suitability index (SI) regression models were SISST-based = 0.7SIeffort-SST + 0.3 SICPUE-SST, and SISSHA-based = 0.5SIeffort-SSHA + 0.5SICPUE-SSHA, respectively, showing that fishing effort is more important than CPUE in the estimation of SI. The best HSI model was the AWM, defined as HSI=0.3SISST-based+ 0.7SISSHA-based, indicating that SSHA is more important than SST in estimating the HSI of squid. In 2004, monthly HSI values greater than 0.6 coincided with the distribution of productive fishing ground and high CPUE in June and July, suggesting that the models perform well. The proposed model provides an important tool in our efforts to develop forecasting capacity of squid spatial dynamics.
