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1.
Science ; 372(6537): 84-87, 2021 04 02.
Artículo en Inglés | MEDLINE | ID: mdl-33795456

RESUMEN

Human activities and climate change threaten marine biodiversity worldwide, though sensitivity to these stressors varies considerably by species and taxonomic group. Mapping the spatial distribution of 14 anthropogenic stressors from 2003 to 2013 onto the ranges of 1271 at-risk marine species sensitive to them, we found that, on average, species faced potential impacts across 57% of their ranges, that this footprint expanded over time, and that the impacts intensified across 37% of their ranges. Although fishing activity dominated the footprint of impacts in national waters, climate stressors drove the expansion and intensification of impacts. Mitigating impacts on at-risk biodiversity is critical to supporting resilient marine ecosystems, and identifying the co-occurrence of impacts across multiple taxonomic groups highlights opportunities to amplify the benefits of conservation management.


Asunto(s)
Biodiversidad , Actividades Humanas , Océanos y Mares , Animales , Organismos Acuáticos , Cambio Climático , Conservación de los Recursos Naturales , Ecosistema , Especies en Peligro de Extinción , Ambiente , Explotaciones Pesqueras , Peces , Humanos , Estrés Fisiológico
2.
Artículo en Inglés | MEDLINE | ID: mdl-33807469

RESUMEN

The necessity for the aquatic ecological risk assessment for benzophenone-3 (BP-3) is increasing due to its high toxic potential and high detection frequency in freshwater. The initial step in the ecological risk assessment is to determine predicted no-effect concentration (PNEC). This study derived PNEC of BP-3 in freshwater using a species sensitivity distribution (SSD) approach, whilst existing PNECs are derived using assessment factor (AF) approaches. A total of eight chronic toxicity values, obtained by toxicity testing and a literature survey, covering four taxonomic classes (fish, crustaceans, algae, and cyanobacteria) were used for PNEC derivation. Therefore, the quantity and quality of the toxicity data met the minimum requirements for PNEC derivation using an SSD approach. The PNEC derived in this study (73.3 µg/L) was far higher than the environmental concentration detected in freshwater (up to 10.4 µg/L) as well as existing PNECs (0.67~1.8 µg/L), mainly due to the difference in the PNEC derivation methodology (i.e., AF vs. SSD approach). Since the SSD approach is regarded as more reliable than the AF approach, we recommend applying the PNEC value derived in this study for the aquatic ecological risk assessment of BP-3, as the use of the existing PNEC values seems to unnecessarily overestimate the potential ecological risk of BP-3 in freshwater.


Asunto(s)
Contaminantes Químicos del Agua , Animales , Organismos Acuáticos , Benzofenonas/toxicidad , Peces , Agua Dulce , Medición de Riesgo , Contaminantes Químicos del Agua/análisis , Contaminantes Químicos del Agua/toxicidad
3.
Science ; 372(6538): 150-156, 2021 04 09.
Artículo en Inglés | MEDLINE | ID: mdl-33833117

RESUMEN

In most vertebrates, camera-style eyes contain retinal ganglion cell neurons that project to visual centers on both sides of the brain. However, in fish, ganglion cells were thought to innervate only the contralateral side, suggesting that bilateral visual projections appeared in tetrapods. Here we show that bilateral visual projections exist in non-teleost fishes and that the appearance of ipsilateral projections does not correlate with terrestrial transition or predatory behavior. We also report that the developmental program that specifies visual system laterality differs between fishes and mammals, as the Zic2 transcription factor, which specifies ipsilateral retinal ganglion cells in tetrapods, appears to be absent from fish ganglion cells. However, overexpression of human ZIC2 induces ipsilateral visual projections in zebrafish. Therefore, the existence of bilateral visual projections likely preceded the emergence of binocular vision in tetrapods.


Asunto(s)
Evolución Biológica , Encéfalo/anatomía & histología , Peces/anatomía & histología , Peces/genética , Células Ganglionares de la Retina/citología , Vías Visuales , Animales , Diferenciación Celular , Ojo/anatomía & histología , Proteínas de Peces/genética , Proteínas de Peces/metabolismo , Peces/metabolismo , Lateralidad Funcional , Humanos , Proteínas Nucleares/genética , Proteínas Nucleares/metabolismo , Retina/embriología , Retina/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Visión Binocular , Pez Cebra/anatomía & histología , Pez Cebra/genética
4.
Artículo en Inglés | MEDLINE | ID: mdl-33806562

RESUMEN

Uptake of the neurotoxicant monomethylmercury (MeHg) from fish and marine mammals continues to present a public health concern in Canada and elsewhere. However, fish and marine mammals are key diet items contributing to food security for some Indigenous populations in Canada. Mercury (Hg) exposure is estimated assuming that 100% of Hg is methylated, that 100% will be absorbed by the consumer and that cooking does not affect MeHg concentrations. Some of these assumptions do not correspond to our current state of knowledge. The aim of this study was to assess the impact of additional variables on Hg exposure equation using probabilistic risk analysis. New variables tested were (1) the proportion of methylated Hg compared to total Hg (pMeHg, %), (2) the relative absorption factor (RAF, %) expressed as bioaccessibility and (3) the mass loss factor (MLF, unitless) that represents the loss of moisture during cooking, known to increase MeHg concentration in fish and mammals. For the new variables, data from literature were used in order to set point estimate values that were further used in the probabilistic risk analysis. Modelling results for both fish and marine mammals indicate that adding these new variables significantly influenced estimates of MeHg exposure (Mood's median test, p < 0.05). This study highlights that the evaluation of exposure to MeHg is sensitive to pMeHg, RAF and MLF, and the inclusion of these variables in risk assessment should be considered with care. Further research is needed to provide better food-dependent, population-specific estimates of RAF and MLF before formal inclusion in exposure estimates.


Asunto(s)
Mercurio , Compuestos de Metilmercurio , Contaminantes Químicos del Agua , Animales , Canadá , Culinaria , Dieta , Peces , Mercurio/análisis , Compuestos de Metilmercurio/análisis , Contaminantes Químicos del Agua/análisis
5.
Artículo en Inglés | MEDLINE | ID: mdl-33808659

RESUMEN

The relationships between land cover characteristics in riparian areas and the biological integrity of rivers and streams are critical in riparian area management decision-making. This study aims to evaluate such relationships using the Trophic Diatom Index (TDI), Benthic Macroinvertebrate Index (BMI), Fish Assessment Index (FAI), and random forest regression, which can capture nonlinear and complex relationships with limited training datasets. Our results indicate that the proportions of land cover types in riparian areas, including urban, agricultural, and forested areas, have greater impacts on the biological communities in streams than those offered by land cover spatial patterns. The proportion of forests in riparian areas has the greatest influence on the biological integrity of streams. Partial dependence plots indicate that the biological integrity of streams gradually improves until the proportion of riparian forest areas reach about 60%; it rapidly decreases until riparian urban areas reach 25%, and declines significantly when the riparian agricultural area ranges from 20% to 40%. Overall, this study highlights the importance of riparian forests in the planning, restoration, and management of streams, and suggests that partial dependence plots may serve to provide insightful quantitative criteria for defining specific objectives that managers and decision-makers can use to improve stream conditions.


Asunto(s)
Diatomeas , Ríos , Agricultura , Algoritmos , Animales , Ecosistema , Peces
6.
J Environ Manage ; 289: 112471, 2021 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-33812145

RESUMEN

Ecosystem functions underpin productivity and key services to humans, such as food provision. However, as the severity of environmental stressors intensifies, it is becoming increasingly unclear if, and to what extent, critical functions and services can be sustained. This issue is epitomised on coral reefs, an ecosystem at the forefront of environmental transitions. We provide a functional profile of a coral reef ecosystem, linking time-series data to quantified processes. The data reveal a prolonged collapse of ecosystem functions in this previously resilient system. The results suggest that sediment accumulation in algal turfs has led to a decline in resource yields to herbivorous fishes and a decrease in fish-based ecosystem functions, including a collapse of both fish biomass and productivity. Unfortunately, at present, algal turf sediment accumulation is rarely monitored nor managed in coral reef systems. Our examination of functions through time highlights the value of directly assessing functions, their potential vulnerability, and the capacity of algal turf sediments to overwhelm productive high-diversity coral reef ecosystems.


Asunto(s)
Antozoos , Arrecifes de Coral , Animales , Ecosistema , Peces , Sedimentos Geológicos , Herbivoria , Humanos
7.
J Environ Manage ; 289: 112375, 2021 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-33813301

RESUMEN

The much-publicized threats to coral reef systems necessitate a considered management response based on comprehensive ecological data. However, data from large reef systems commonly originate from multiple monitoring programs that use different methods, each with distinct biases that limit united assessments of ecological status. The effective integration of data from different monitoring methods would allow better assessment of system status and hence, more informed management. Here we examine the scope for comparability and complementarity of fish data from two different methods used on Australia's Great Barrier Reef (GBR): underwater visual census (UVC) and baited remote underwater video stations (BRUVS). We compared commonly reported reef fish measures from UVC and BRUVS on similar reef slope habitats of three central GBR reefs. Both methods recorded similar estimates of total species richness, although ~30% of recorded species were not common to both methods. There were marked differences between methods in sub-group species richness, frequency of species occurrences, relative abundances of taxa and assemblage structure. The magnitude and orientation of inter-method differences were often inconsistent among taxa. However, each method better categorized certain components of fish communities: BRUVS sampled more predatory species in higher numbers while UVC was similarly better at sampling damselfishes (Pomacentridae). Our results suggest limited scope for direct or adjusted comparisons of data from UVC and BRUVS. Conversely, complementary aspects of the two methods confirm that their integration in monitoring programs will provide a more complete and extensive assessment of reef fish status for managers than from either method alone.


Asunto(s)
Biodiversidad , Censos , Animales , Arrecifes de Coral , Ecosistema , Peces
8.
BMC Ecol Evol ; 21(1): 54, 2021 04 12.
Artículo en Inglés | MEDLINE | ID: mdl-33845757

RESUMEN

BACKGROUND: Placentation has evolved multiple times among both chordates and invertebrates. Although they are structurally less complex, invertebrate placentae are much more diverse in their origin, development and position. Aquatic colonial suspension-feeders from the phylum Bryozoa acquired placental analogues multiple times, representing an outstanding example of their structural diversity and evolution. Among them, the clade Cyclostomata is the only one in which placentation is associated with viviparity and polyembryony-a unique combination not present in any other invertebrate group. RESULTS: The histological and ultrastructural study of the sexual polymorphic zooids (gonozooids) in two cyclostome species, Crisia eburnea and Crisiella producta, revealed embryos embedded in a placental analogue (nutritive tissue) with a unique structure-comprising coenocytes and solitary cells-previously unknown in animals. Coenocytes originate via nuclear multiplication and cytoplasmic growth among the cells surrounding the early embryo. This process also affects cells of the membranous sac, which initially serves as a hydrostatic system but later becomes main part of the placenta. The nutritive tissue is both highly dynamic, permanently rearranging its structure, and highly integrated with its coenocytic 'elements' being interconnected via cytoplasmic bridges and various cell contacts. This tissue shows evidence of both nutrient synthesis and transport (bidirectional transcytosis), supporting the enclosed multiple progeny. Growing primary embryo produces secondary embryos (via fission) that develop into larvae; both the secondary embyos and larvae show signs of endocytosis. Interzooidal communication pores are occupied by 1‒2 specialized pore-cells probably involved in the transport of nutrients between zooids. CONCLUSIONS: Cyclostome nutritive tissue is currently the only known example of a coenocytic placental analogue, although syncytial 'elements' could potentially be formed in them too. Structurally and functionally (but not developmentally) the nutritive tissue can be compared with the syncytial placental analogues of certain invertebrates and chordates. Evolution of the cyclostome placenta, involving transformation of the hydrostatic apparatus (membranous sac) and change of its function to embryonic nourishment, is an example of exaptation that is rather widespread among matrotrophic bryozoans. We speculate that the acquisition of a highly advanced placenta providing massive nourishment might support the evolution of polyembryony in cyclostomes. In turn, massive and continuous embryonic production led to the evolution of enlarged incubating polymorphic gonozooids hosting multiple progeny.


Asunto(s)
Briozoos , Animales , Femenino , Peces , Invertebrados , Placenta , Placentación , Embarazo
9.
Environ Monit Assess ; 193(5): 255, 2021 Apr 09.
Artículo en Inglés | MEDLINE | ID: mdl-33835292

RESUMEN

We performed a preliminary evaluation of a mobile sampling platform with adjustable push net and live box (Platform) against two common methods for sampling small-bodied fish (i.e., 10-100 mm) in two distinct lentic habitats. Nearshore (NS) littoral habitat was sampled by Platform and beach seine, and open water (OW) pelagic habitat by Platform and Kodiak trawl. Our goal was to evaluate the Platform's ability to describe fish assemblage structure across habitat types in contrast to common techniques restricted to single habitat types that are less comparable due to gear-specific bias. Platform sample speed had a significant positive effect on recapture efficiency of both nearly neutrally buoyant objects and marked fish. Marked fish recapture efficiencies were similar for Platform in NS and OW, indicating similar efficiency across habitat types. Platform capture efficiency was similar to beach seine and greater than Kodiak trawl. With similar sampling time, the Platform collected more individuals and taxa in NS relative to beach seine and in OW relative to Kodiak trawl. Greater taxa detection by the Platform suggests that it may be effective at detecting species that are numerically rare in specific habitats when compared to these methods. Fish CPUE was significantly greater NS regardless of technique. However, by using the Platform, there is greater confidence that this difference was reliable and not a gear selectivity artifact. Overall, this preliminary study demonstrates the Platform's potential to collect standardized data across NS and OW habitats, track ontogenetic habitat shifts, and detect differences in small-bodied fish taxa richness, relative abundance, and density between NS and OW habitats. Continued experimentation beyond a single reservoir and fish size range is required before consensus can be established regarding the utility of this new push net design.


Asunto(s)
Monitoreo del Ambiente , Agua , Animales , Ecosistema , Peces , Humanos
10.
Nat Commun ; 12(1): 1586, 2021 03 11.
Artículo en Inglés | MEDLINE | ID: mdl-33707438

RESUMEN

Human-driven threats are changing biodiversity, impacting ecosystem services. The loss of one species can trigger secondary extinctions of additional species, because species interact-yet the consequences of these secondary extinctions for services remain underexplored. Herein, we compare robustness of food webs and the ecosystem services (hereafter 'services') they provide; and investigate factors determining service responses to secondary extinctions. Simulating twelve extinction scenarios for estuarine food webs with seven services, we find that food web and service robustness are highly correlated, but that robustness varies across services depending on their trophic level and redundancy. Further, we find that species providing services do not play a critical role in stabilizing food webs - whereas species playing supporting roles in services through interactions are critical to the robustness of both food webs and services. Together, our results reveal indirect risks to services through secondary species losses and predictable differences in vulnerability across services.


Asunto(s)
Ecosistema , Extinción Biológica , Cadena Alimentaria , Animales , Biodiversidad , Aves , Cambio Climático/estadística & datos numéricos , Peces , Humanos , Modelos Biológicos
11.
Nat Commun ; 12(1): 1701, 2021 03 15.
Artículo en Inglés | MEDLINE | ID: mdl-33723261

RESUMEN

Climate change poses a significant threat to global biodiversity, but freshwater fishes have been largely ignored in climate change assessments. Here, we assess threats of future flow and water temperature extremes to ~11,500 riverine fish species. In a 3.2 °C warmer world (no further emission cuts after current governments' pledges for 2030), 36% of the species have over half of their present-day geographic range exposed to climatic extremes beyond current levels. Threats are largest in tropical and sub-arid regions and increases in maximum water temperature are more threatening than changes in flow extremes. In comparison, 9% of the species are projected to have more than half of their present-day geographic range threatened in a 2 °C warmer world, which further reduces to 4% of the species if warming is limited to 1.5 °C. Our results highlight the need to intensify (inter)national commitments to limit global warming if freshwater biodiversity is to be safeguarded.


Asunto(s)
Peces , Agua Dulce , Calentamiento Global , Animales , Biodiversidad , Cambio Climático , Calor , Modelos Biológicos , Filogenia , Especificidad de la Especie , Temperatura
12.
Int J Mol Sci ; 22(4)2021 Feb 11.
Artículo en Inglés | MEDLINE | ID: mdl-33670421

RESUMEN

Far from being devoid of life, Antarctic waters are home to Cryonotothenioidea, which represent one of the fascinating cases of evolutionary adaptation to extreme environmental conditions in vertebrates. Thanks to a series of unique morphological and physiological peculiarities, which include the paradigmatic case of loss of hemoglobin in the family Channichthyidae, these fish survive and thrive at sub-zero temperatures. While some of the distinctive features of such adaptations have been known for decades, our knowledge of their genetic and molecular bases is still limited. We generated a reference de novo assembly of the icefish Chionodraco hamatus transcriptome and used this resource for a large-scale comparative analysis among five red-blooded Cryonotothenioidea, the sub-Antarctic notothenioid Eleginops maclovinus and seven temperate teleost species. Our investigation targeted the gills, a tissue of primary importance for gaseous exchange, osmoregulation, ammonia excretion, and its role in fish immunity. One hundred and twenty genes were identified as significantly up-regulated in Antarctic species and surprisingly shared by red- and white-blooded notothenioids, unveiling several previously unreported molecular players that might have contributed to the evolutionary success of Cryonotothenioidea in Antarctica. In particular, we detected cobalamin deficiency signatures and discussed the possible biological implications of this condition concerning hematological alterations and the heavy parasitic loads typically observed in all Cryonotothenioidea.


Asunto(s)
Aclimatación , Peces , Branquias/metabolismo , Transcriptoma , Deficiencia de Vitamina B 12 , Vitamina B 12/metabolismo , Animales , Regiones Antárticas , Peces/genética , Peces/metabolismo , Deficiencia de Vitamina B 12/genética , Deficiencia de Vitamina B 12/metabolismo
13.
Ying Yong Sheng Tai Xue Bao ; 32(3): 1069-1079, 2021 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-33754574

RESUMEN

Based on seasonal bottom trawl surveys in November 2015 (autumn), February (winter), May (spring) and August (summer) in 2016, the index of relative importance (IRI), Shannon index and Pianka index were used to analyze the breadth and overlap of spatio-temporal niche of major fish species in the Pishan waters off Zhejiang Province. Redundancy analysis and interspecific competition coefficient were used to examine the competition relationship and niche differentiation of those major fish species. The results showed that a total of 61 fish species were recorded throughout the year, which belonged to 13 orders, 29 families and 48 genera. A total of 19 species with IRI>100 were identified as major fish species. The temporal niche overlap value between Chelidonichthys kumu and Atule kalla was largest, indicating high temporal synchronization. Both the spatial niche overlap value and the spatio-temporal niche overlap value between Trpauchen vagina and Cynoglossus interruptus were largest, indicating that their spatial homology was high and that the use of spatial and temporal two-dimensional resource of both species were consistent. The percentage of species pairs with spatio-temporal niche overlap at the significant level (Qik>0.6) was only 5.8% in Pishan waters, indicating that the spatial and temporal distribution of those species were quite different. The overlap of spatio-temporal niche significantly varied across different seasons. The results of the interspecific competition coefficient were basically consistent with the niche overlap. Results of the redundancy analysis revealed the relationships between major fish species and environmental factors (temperature, salinity, dissolved oxygen), and further explained the niche diffe-rentiation among species.


Asunto(s)
Ecosistema , Peces , Animales , China , Humanos , Salinidad , Estaciones del Año
14.
Sci Total Environ ; 768: 144580, 2021 May 10.
Artículo en Inglés | MEDLINE | ID: mdl-33736339

RESUMEN

The survival of aquatic biota in different life history stages depends on food availability, water quantity and specific hydrological conditions, and is particularly susceptible in degraded rivers due to the development of hydropower or are sensitive to climate change. Habitats with limited food availability and restricted feeding opportunities can strongly affect the habitat carrying capacity and fish growth with consequences for spawning. Few environmental flow regime frameworks are available that closely link bait and feeding opportunities to fish foraging habitat. In addition, river restoration has been widely implemented to resolve the conflict between ecological demand and power generation benefits. Nevertheless, whether in-stream structures are still suitable for the joint operation of foraging and spawning habitats remains unclear. In this study, a framework to integrate the requirements of both spawning and foraging habitats into environmental flow regime assessments was proposed by coupling the bait supply, fish spawning and fish feeding opportunities. Here, we used the Batang Reservoir, located in the Tibetan Plateau, as an example to determine the environmental flow regimes. The environmental flow regimes during Periods I, II and III for the conservation of the life history stages of Schizothorax dolichonem were determined, which provided high-quality food and was beneficial for increasing the probability of restoration success. After the implementation of measures, the ecological base flow rate decreased from 171.80 m3/s, 206.00 m3/s and 257.70 m3/s to 138.00 m3/s, 206.00 m3/s and 206.00 m3/s in Periods I, II and III, respectively. We concluded that traditional river restoration with the use of in-stream structures is still suitable for the joint operation of spawning and foraging habitats, but the design selection and placement of in-stream structures should be preoptimized. The framework proposed will help managers evaluate habitat conservation to protect degraded rivers or help develop strategies to build resilience to climate change.


Asunto(s)
Monitoreo del Ambiente , Ríos , Animales , Cambio Climático , Ecosistema , Peces , Hidrología
15.
Sci Total Environ ; 770: 144722, 2021 May 20.
Artículo en Inglés | MEDLINE | ID: mdl-33736366

RESUMEN

Warming, land-use change, and habitat loss are three major threats to aquatic biodiversity worldwide under the influences of anthropogenic disturbances. Positive feedback between warming and bottom-up regulation may cause irreversible ecological regime shifts. Threshold dynamics of interspecific interactions have been rarely studied in freshwater fish communities using threshold community models. Here we use 66 years (1950-2015) of data to link four ecological regime shifts of 9-species fish communities to climatic and land use changes in Lake Hulun, the largest freshwater lake of Northern China. Overfishing caused the collapse of piscivorous fish populations and an ecological regime shift of Lake Hulun in the late 1950s. The first recorded algal bloom of Lake Hulun took place in 1986, with accelerated warming and rapid increases in livestock grazing. The dominance of planktivorous minnow populations reduced fish biodiversity in a nonlinear, threshold manner when annual mean ambient temperature was >0.12 °C. Multivariate environmental vector regression demonstrated that warming, eutrophication, and water-storage reduction (i.e., habitat loss) were related to three ecological regime shifts of Lake Hulun from 1960 to 2015. Multivariate autoregressive models (MAR) did not detect predation by piscivorous fish in Lake Hulun after 1960. Threshold MAR models indicated that dominant minnow populations and other prey fish populations switched from top-down to bottom-up control during the 1980s. Sustained positive feedback between warming, the dominance of planktivorous fish populations, and bottom-up regulation caused predator-prey role reversal, and probably resulted in three regime shifts of Lake Hulun over 56 years. This study provides a comprehensive analysis of ecological regime shifts in Hulun Lake fish communities, and has potential implications for fish species living in similar environments that are subject to global warming, land-use changes, and overfishing.


Asunto(s)
Conservación de los Recursos Naturales , Lagos , Animales , China , Cambio Climático , Ecosistema , Explotaciones Pesqueras , Peces
16.
Ecotoxicol Environ Saf ; 214: 112098, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33662787

RESUMEN

The Deepwater Horizon blowout resulted in the second-largest quantity of chemical dispersants used as a countermeasure for an open water oil spill in the Gulf of Mexico. Of which, the efficacy of dispersant as a mitigation strategy and its toxic effects on aquatic fauna remains controversial. To enhance our understanding of potential sub-lethal effects of exposure to chemically dispersed-oil, sub-adult red drum (Sciaenops ocellatus) were continuously exposed to a Corexit 9500: DWH crude oil chemically enhanced water accommodated fraction (CEWAF) for 3-days and transcriptomic responses were assessed in the liver. Differential expressed gene (DEG) analysis demonstrated that 63 genes were significantly impacted in the CEWAF exposed fish. Of these, 37 were upregulated and 26 downregulated. The upregulated genes were primarily involved in metabolism and oxidative stress, whereas several immune genes were downregulated. Quantitative real-time RT-PCR further confirmed upregulation of cytochrome P450 and glutathione S-transferase, along with downregulation of fucolectin 2 and chemokine C-C motif ligand 20. Ingenuity Pathway Analysis (IPA) predicted 120 pathways significantly altered in the CEWAF exposed red drum. The aryl hydrocarbon receptor pathway was significantly activated, while pathways associated with immune and cellular homeostasis were primarily suppressed. The results of this study indicate that CEWAF exposure significantly affects gene expression and alters signaling of biological pathways important in detoxification, immunity, and normal cellular physiology, which can have potential consequences on organismal fitness.


Asunto(s)
Perciformes/fisiología , Contaminación por Petróleo , Petróleo/toxicidad , Transcriptoma/fisiología , Contaminantes Químicos del Agua/toxicidad , Animales , Peces , Perfilación de la Expresión Génica , Golfo de México , Lípidos , Hígado/química , Contaminación por Petróleo/análisis , Agua/análisis
17.
Ecotoxicol Environ Saf ; 214: 112099, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33714139

RESUMEN

Although fish are widely confirmed to be susceptible to heavy metals (HMs) contamination in sediments, this bioconversion haven't been detailed. This is especially the case in karst areas, where HMs are less stably retained in the sediments and are more bioavailable. Therefore, we surveyed representative karst rivers in Liuzhou, China, in order to study the relationship between the speciations of seven HMs in the sediments with their bioaccumulation in wild fish. The results showed that the HMs in sediments are all below their permissible exposure limit (PEL), but Cd and Zn are significantly higher than soil basline. Most HMs are in residual fraction, while their exchangeable fractions are present in extremely low proportions. The concentration of Zn, Cr and Cd in some fish are above their maximum recommended limit (MRL). The concentrations of most of the HMs in the fish are significantly correlated with the levels in the sediments and given the higher correlation coefficients for their carbonate-bound phase, this phase can be seen to play a critical role in HMs bioconversion. However, the presence of this phase in low proportions enables other phases, especially oxidizable form, to play a greater role in HMs bioaccumulation. Apart from Do, HMs in the fish samples are significantly correlated with multiple environmental factors, demonstrating environmental fluctuations can manipulate HMs bioconversion from sediments; however, their significance depend heavily on the proportion of particular species. HMs in reducible and oxidizable fraction are more important in regulating, rather than promoting, their bioconversion during environmental fluctuations. Fluctuations in EC, TDS and pH can increase the impacts of HMs in carbonate-bound fraction on their bioconversion. Given the higher background values of EC and TDS and lower pH values during the monsoon period, careful attention should be paid to the increased bioconversion of HMs in karst rivers during this season.


Asunto(s)
Monitoreo del Ambiente , Peces/fisiología , Metales Pesados/toxicidad , Contaminantes Químicos del Agua/toxicidad , Animales , Bioacumulación , China , Sedimentos Geológicos , Metales Pesados/análisis , Medición de Riesgo , Ríos , Estaciones del Año , Suelo , Contaminantes Químicos del Agua/análisis
18.
Environ Monit Assess ; 193(4): 235, 2021 Mar 29.
Artículo en Inglés | MEDLINE | ID: mdl-33779861

RESUMEN

The Okobaba area of the Lagos Lagoon, Nigeria, is characterised by sawmilling activities which are potential threats to resident aquatic organisms. This study was aimed at evaluating the effect of sawmilling activities on the environmental quality of the Lagos lagoon at Okobaba area, Lagos, Nigeria. Surface water, sediment, macrobenthic invertebrates, and fish species were sampled monthly from six stations for 3 months (July-September 2018). Relevant stakeholders were administered a cross-sectional questionnaire to determine their knowledge of the environmental effects of their activities. Environmental samples were analysed following standard methods. Descriptive and inferential statistics were performed using SPSS 20.0 and PAST 1.97. Results showed that surface water dissolved oxygen and chemical oxygen demand were significantly lower, while sediment total organic matter and nitrates were significantly higher at the test site compared to the reference site. A total of 389 macrobenthic invertebrates comprising eight species and two macrobenthic invertebrates comprising one species as well as 121 fishes comprising nine species and 70 fishes comprising nine (9) species were recorded at the reference and test sites respectively. About 46.3% of respondents alluded to improper waste disposal as the major cause of pollution at the test site among others, 66.7% responded that wastes were disposed of by burning among other disposal methods, and 66.6% agreed that the sawmilling activities contributed to reduction of aquatic animal population. We recommend urgent regulatory intervention to address the indiscriminate discharge of wastes and facilitate adequate environmental risk advocacy to sustain life below water (United Nations Sustainable Development Goal 14).


Asunto(s)
Sedimentos Geológicos , Contaminantes Químicos del Agua , Animales , Estudios Transversales , Monitoreo del Ambiente , Peces , Invertebrados , Nigeria , Agua , Contaminantes Químicos del Agua/análisis
19.
Zootaxa ; 4915(3): zootaxa.4915.3.2, 2021 Jan 22.
Artículo en Inglés | MEDLINE | ID: mdl-33756560

RESUMEN

Historically, the taxonomic identification of the two snook species, Centropomus viridis and C. nigrescens, has been challenging due to their morphological similarity and the inconsistency of the characters used for diagnosis. Therefore, this study aimed to evaluate the usefulness of the morphologic, meristic, and morphometric characters currently being used to identify C. viridis and C. nigrescens, based on molecular data. The results showed that the gas-bladder shape (i.e., C. viridis with diverticula and C. nigrescens without diverticula) was the only morphological character univocally related to genetic identification. Likewise, geometric morphometrics separated two groups; each corresponds to only one of two genetically (and gas bladder shape) identified species. Of all the meristic characters examined, only the second dorsal fin ray count (nine for C. viridis and ten for C. nigrescens) was related to the gas bladder shape and genetic identity; therefore, it is the only external character with a diagnostic utility to separate each species.


Asunto(s)
Perciformes , Animales , Peces
20.
Zootaxa ; 4926(2): zootaxa.4926.2.10, 2021 Feb 05.
Artículo en Inglés | MEDLINE | ID: mdl-33756755

RESUMEN

Coralliozetus clausus, a new species of chaenopsid blenny, endemic to Isla del Coco, Costa Rica, is described. This small species, not exceeding 15 mm SL, is a short-bodied member of the genus along with Coralliozetus cardonae (Caribbean), Coralliozetus angelicus, and Coralliozetus springeri (both eastern Pacific). It differs from its closest relative, C. springeri, known from mainland waters from Costa Rica to Ecuador, in having a single tiny supraorbital cirrus and dark dots on the operculum and branchiostegal membrane of males while C. springeri has paired supraorbital cirri (one of which is substantial in size) and no dots on the operculum. Although two other species of Coralliozetus have been reported from Isla del Coco, this appears to be only member of the genus present on the island. It is the second chaenopsid endemic to Isla del Coco and brings the number of cryptobenthic fishes endemic to Isla del Coco to twelve.


Asunto(s)
Cocos , Animales , Costa Rica , Peces , Masculino
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