Fishes use environmental resources differently.Snapper ontogenic movements among coastal habitats lead to diverse diets.We investigated the diets of seven snapper species(Lutjanus apodus,L.analis,L.griseus,L.jocu,L.ma...Fishes use environmental resources differently.Snapper ontogenic movements among coastal habitats lead to diverse diets.We investigated the diets of seven snapper species(Lutjanus apodus,L.analis,L.griseus,L.jocu,L.mahogoni,L.synagris,and Ocyurus chrysurus)in three interconnected coastal environments in the western Caribbean:Río Huach channel,Chetumal/Corozal bay,and the adjacent Xcalak reef lagoon.These three encompass all habitats used by the seven species in the study area.Snapper diets were mostly composed of fish and crustaceans,but dominance of either group varied among the studied habitats;for example,fish were the main prey for L.apodus from the reef lagoon zone,but second in the bay.Snappers are piscivorous-invertivorous mesopredators;the species that relied the most on fishes were L.griseus and L.jocu,whereas O.chrysurus preferred crustaceans.Stomach content results revealed a high degree of dietary overlap among species.Our findings suggested a tradeoff in relative weight between fish and crustaceans as the main food source of snappers at these connected areas,supporting the hypothesis of niche segregation.Our results can be used as a baseline to further our understanding of the ecology and differences in resource use by snapper species in an area undergoing important anthropogenic changes.展开更多
Mentum deformities in chironomids have been commonly used as indicators of metal contamination in freshwater ecosystems.Incidence of these deformities suggests sublethal effects and can provide early signals of enviro...Mentum deformities in chironomids have been commonly used as indicators of metal contamination in freshwater ecosystems.Incidence of these deformities suggests sublethal effects and can provide early signals of environmental deterioration.While anthropogenic metal pollution is known to lead to an increase in deformities in chironomids,natural background deformity incidence information is key to their effective use as biomonitoring tools.Here we explore the incidence of deformities from 5000 Tanytarsus(Diptera,Chironomidae)menta in relation to water physicochemical,and sediment metal(Al,As,Cu,Fe,Mn,Pb,Zn)concentration data from numerous sites in the naturally metal-rich Sonora River(NW Mexico)obtained over a two-year period.Higher metal concentrations were found in the upper basin.Higher salinity,total suspended solids and conductivity were found in the lower basin.Only As and Cu were occasionally found above published threshold effect levels(TEL).The proportion of deformities(%D)was low(2.1%)and a generalized linear model only explained 25.36%of%D variability among samples;this model included several physicochemical parameters.The only metal significantly related to deformities was Cu.Despite significant spatial and temporal variability in all metal concentrations and other physicochemical parameters in the basin,we were unable to explain a strong relationship between metal concentration and deformity incidence.Our results,based on consistent%D quantification from 5000 samples from a single taxon,suggest that natural variation in metal concentrations,even when statistically significant,is not associated with notable variations in the incidence of deformities.展开更多
Abundances of important and imperiled fishes of the Snake River Basin continue to decline.We assessed the rationale for breaching the four lower Snake River Basin dams to prevent complete loss of these fishes,and to m...Abundances of important and imperiled fishes of the Snake River Basin continue to decline.We assessed the rationale for breaching the four lower Snake River Basin dams to prevent complete loss of these fishes,and to maximize their likelihood of recovery.We summarize the science surrounding Sockeye Salmon(Oncorhynchus nerka),Chinook Salmon(O.tshawytscha),steelhead(O.mykiss),Bull Trout(Salvelinus confluentus),White Sturgeon(Acipenser transmontanus),and Pacific Lamprey(Entosphenus tridentatus).From this,we drew ten conclusions:(1)development of the Columbia River System(including the Snake River Basin)has converted mainstem rivers into reservoirs,altering fish behavior and survival;(2)most populations currently record their lowest abundance;(3)the Columbia River System dams reduce productivity of diadromous fishes in the highest-quality spawning grounds that could buffer against future climate dynamics;(4)past actions have done little to reduce impacts or precipitate recovery;(5)the Columbia River System constrains survival and productivity of salmon,steelhead and Bull Trout;(6)Snake River Basin salmon and steelhead remain at high extinction risk;(7)eliminating migration impediments and improving mainstem habitats are essential for maintaining genetic diversity and improving Bull Trout persistence;(8)the lower Snake River Basin dams preclude passage of adult White Sturgeon,constraining gene flow and recruitment;(9)the lower Snake River Basin dams impede dramatically passage of adult and juvenile Pacific Lamprey,and(10)Snake River Basin Pacific Lamprey is at high risk of extirpation.Breaching the four lower Snake River Basin dams is an action likely to prevent extirpation and extinction of these fishes.Lessons from the Columbia River System can inform conservation in other impounded rivers.展开更多
文摘Fishes use environmental resources differently.Snapper ontogenic movements among coastal habitats lead to diverse diets.We investigated the diets of seven snapper species(Lutjanus apodus,L.analis,L.griseus,L.jocu,L.mahogoni,L.synagris,and Ocyurus chrysurus)in three interconnected coastal environments in the western Caribbean:Río Huach channel,Chetumal/Corozal bay,and the adjacent Xcalak reef lagoon.These three encompass all habitats used by the seven species in the study area.Snapper diets were mostly composed of fish and crustaceans,but dominance of either group varied among the studied habitats;for example,fish were the main prey for L.apodus from the reef lagoon zone,but second in the bay.Snappers are piscivorous-invertivorous mesopredators;the species that relied the most on fishes were L.griseus and L.jocu,whereas O.chrysurus preferred crustaceans.Stomach content results revealed a high degree of dietary overlap among species.Our findings suggested a tradeoff in relative weight between fish and crustaceans as the main food source of snappers at these connected areas,supporting the hypothesis of niche segregation.Our results can be used as a baseline to further our understanding of the ecology and differences in resource use by snapper species in an area undergoing important anthropogenic changes.
基金This project was carried out with support from CONACYT to OCBG(Author)via Graduate(MS)Scholarship No:903227Support was also provided by project 84460256 to the Instituto Mexicano de Tecnología del Agua and project PRODEP project DSA/103.5/15/3073 to NMS(Author).
文摘Mentum deformities in chironomids have been commonly used as indicators of metal contamination in freshwater ecosystems.Incidence of these deformities suggests sublethal effects and can provide early signals of environmental deterioration.While anthropogenic metal pollution is known to lead to an increase in deformities in chironomids,natural background deformity incidence information is key to their effective use as biomonitoring tools.Here we explore the incidence of deformities from 5000 Tanytarsus(Diptera,Chironomidae)menta in relation to water physicochemical,and sediment metal(Al,As,Cu,Fe,Mn,Pb,Zn)concentration data from numerous sites in the naturally metal-rich Sonora River(NW Mexico)obtained over a two-year period.Higher metal concentrations were found in the upper basin.Higher salinity,total suspended solids and conductivity were found in the lower basin.Only As and Cu were occasionally found above published threshold effect levels(TEL).The proportion of deformities(%D)was low(2.1%)and a generalized linear model only explained 25.36%of%D variability among samples;this model included several physicochemical parameters.The only metal significantly related to deformities was Cu.Despite significant spatial and temporal variability in all metal concentrations and other physicochemical parameters in the basin,we were unable to explain a strong relationship between metal concentration and deformity incidence.Our results,based on consistent%D quantification from 5000 samples from a single taxon,suggest that natural variation in metal concentrations,even when statistically significant,is not associated with notable variations in the incidence of deformities.
文摘Abundances of important and imperiled fishes of the Snake River Basin continue to decline.We assessed the rationale for breaching the four lower Snake River Basin dams to prevent complete loss of these fishes,and to maximize their likelihood of recovery.We summarize the science surrounding Sockeye Salmon(Oncorhynchus nerka),Chinook Salmon(O.tshawytscha),steelhead(O.mykiss),Bull Trout(Salvelinus confluentus),White Sturgeon(Acipenser transmontanus),and Pacific Lamprey(Entosphenus tridentatus).From this,we drew ten conclusions:(1)development of the Columbia River System(including the Snake River Basin)has converted mainstem rivers into reservoirs,altering fish behavior and survival;(2)most populations currently record their lowest abundance;(3)the Columbia River System dams reduce productivity of diadromous fishes in the highest-quality spawning grounds that could buffer against future climate dynamics;(4)past actions have done little to reduce impacts or precipitate recovery;(5)the Columbia River System constrains survival and productivity of salmon,steelhead and Bull Trout;(6)Snake River Basin salmon and steelhead remain at high extinction risk;(7)eliminating migration impediments and improving mainstem habitats are essential for maintaining genetic diversity and improving Bull Trout persistence;(8)the lower Snake River Basin dams preclude passage of adult White Sturgeon,constraining gene flow and recruitment;(9)the lower Snake River Basin dams impede dramatically passage of adult and juvenile Pacific Lamprey,and(10)Snake River Basin Pacific Lamprey is at high risk of extirpation.Breaching the four lower Snake River Basin dams is an action likely to prevent extirpation and extinction of these fishes.Lessons from the Columbia River System can inform conservation in other impounded rivers.
