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"Fish populations"
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Multidecadal changes in fish composition and traits diversity in a marine park in the Gulf of California
No-take marine reserves allow overexploited fish populations to rebound. However, whether the resilience level of the community may recover is an open question. A community’s resilience to disturbances depends on the diversity of the species’ traits. We analyzed reef fish assemblages over 30 years in a no-take marine reserve to determine whether the fish composition and its ecological traits structure recovered after protection. We selected the National Park of Cabo Pulmo in the Gulf of California (Mexico), which is a model marine protected area because of its good management. From 1987 to 2017, fish assemblages were monitored to quantify species richness, density, and evenness. The ecological traits structure of the assemblages was computed using the traits richness, dispersion, and redundancy. We observed three distinct phases: (i) a decline period from 1987 to 1998 during which the species richness and fish density severely decreased due to resources exploitation and coral reef damage; (ii) a fish density recovery period following the creation of the reserve from 1998 to 2011; and (iii) a mature period where fish assemblages appear to be stable. However, during the fish recovery period, the fish composition changed. Some species became highly dominant while other species that were abundant during the pre-disturbance period did not recuperate. Thus, the fish assemblages’ evenness, traits dispersion, and traits redundancy decreased during the recovery period before stabilizing, probably decreasing the resilience ability of the community. Although Cabo Pulmo marine park is a success story since the fish density recovered, the prohibition of resource extraction alone did not restore the past resilience level of the fish assemblages, which may make them more vulnerable to future environmental disturbances.
Journal Article
Evaluation of water quality and dam for sustaining the fish population dynamics
Bhagirathi is a Himalayan River, which flows in Uttrakashi district in Uttarakhand state. It is one of the most important streams of the Ganga River. This river is famous for dam construction and fisheries development. The fishes of commercial importance in cold water are Mahaseer, Snow Trout. The fish production depends on the physical, chemical as well as biological qualities of water. In the present paper, water quality evaluation and dam in the sustaining fish population dynamics have been reviewed to make aware the fish culturist and environmentalist about the water quality factors which influence health of a pond and to increase the fish yields to meet the growing demands of present time scenario of the our country. The construction of dams causes many problems. Water quality and discharge of water from the dam wall systems also indirectly affect the fish populations. In this study, we also review some of the important impacts associated with dams and their recommended mitigation measures. There is a negative impact on fish population dynamics, especially for downstream habits due to dams. Water quality is measured like temperature, turbidity, carbon dioxide, pH, alkalinity, hardness, BOD, TDS, Turbidity. The maximum oxygen content of water was recorded in January 13.02 ± 0.166 mg l
−1
and minimum 9.4 ± 0.05 mg l
−1
in July in site I phase I (before the reservoir dam wall). While in site II and phase I (After the dam), the maximum DO was observed in the month of January of 12.1 mg l
−1
and minimum in July of 8.93 mg l
−1.
This is because water level is minimized in site II almost dried in winter. The CO
2
of the Maneri Bhali phase I -Site I (before dam) was recorded maximum in April 3.10 ± 0.012 mg l
−1
. In Maneri Bhali phase I -Site II (After dam), the CO
2
was recorded maximum 3.01 ± 0.003 mg l
−1
in the month July. The river of Garhwal Himalaya harbors a rich aquatic diversity, the most common endemic fish species that inhabit this fresh water is the
Schizothorax
species. The maximum no. of fish were observed in winter and minimum in monsoon. At present, the production of these fishes from the streams is very poor and is not well managed from recreational and conservation point of view. If such is developed properly, it can have revenue potential for our state government. Sports, fisheries, tourism should be promoted.
Journal Article
Prediction and Analysis of the Temperature of British Seas in the Next 50 Years Based on the Grey Model
Li, H.; Xu, F., and Wan, F., 2020. Prediction and analysis of the temperature of British Seas in the next 50 years based on the Grey Model. In: Liu, X. and Zhao, L. (eds.), Today's Modern Coastal Society: Technical and Sociological Aspects of Coastal Research. Journal of Coastal Research, Special Issue No. 111, pp. 7–15. Coconut Creek (Florida), ISSN 0749-0208. The increase in temperature in the surface of the ocean will cause great changes in the living environment of fish. The increase in temperature will reduce the solubility of carbon dioxide, the insufficient absorption of carbon in seawater, and will decrease the concentration of dissolved oxygen. Most fish will migrate, and in view of the current global warming trend, they will gradually move their habitats to more suitable temperature areas. To predict the effect of this temperature change on human production and life, we established two mathematical models to predict the temperature and the number of two economic fish populations. Model 1 addresses how quickly the waters around Scotland changed from 1980 to 2070. We used the sea-surface temperature data from the National Aeronautics and Space Administration Ocean Color website for the past 40 years to make predictions for the next 50 years. The Grey prediction model was used to complete a small data sample on the time series to predict a large unknown amount of data. To illustrate the prediction process, a single-point prediction process is chosen as an example. The forecast result isotherms of all forecast areas are also provided. Model 2 uses the data from Model 1. First, the relationship between temperature changes and the number of fish is studied. The quantity of fish that fishermen can catch in the sea area under the best and worst conditions is given, including the time for small fisheries companies to be bankrupt. In the forecasting process, fish living temperature data from the Fishbase website was obtained and a function between temperature and population was established according to a normal distribution model. Furthermore, the minimum fish density and its arriving time, which can make a small fishery company bankrupt under the temperature change, are also completed.
Journal Article
Plants on the Moon, US emissions spike and fish die-off
The week in science: 11-17 January 2019.
Journal Article
Optimal Automatic Wide-Area Discrimination of Fish Shoals from Seafloor Geology with Multi-Spectral Ocean Acoustic Waveguide Remote Sensing in the Gulf of Maine
Ocean Acoustic Waveguide Remote Sensing (OAWRS) enables fish population density distributions to be instantaneously quantified and continuously monitored over wide areas. Returns from seafloor geology can also be received as background or clutter by OAWRS when insufficient fish populations are present in any region. Given the large spatial regions that fish inhabit and roam over, it is important to develop automatic methods for determining whether fish are present at any pixel in an OAWRS image so that their population distributions, migrations and behaviour can be efficiently analyzed and monitored in large data sets. Here, a statistically optimal automated approach for distinguishing fish from seafloor geology in OAWRS imagery is demonstrated with Neyman–Pearson hypothesis testing which provides the highest true-positive classification rate for a given false-positive rate. Multispectral OAWRS images of large herring shoals during spawning migration to Georges Bank are analyzed. Automated Neyman-Pearson hypothesis testing is shown to accurately distinguish fish from seafloor geology through their differing spectral responses at any space and time pixel in OAWRS imagery. These spectral differences are most dramatic in the vicinity of swimbladder resonances of the fish probed by OAWRS. When such significantly different spectral dependencies exist between fish and geologic scattering, the approach presented provides an instantaneous, reliable and statistically optimal means of automatically distinguishing fish from seafloor geology at any spatial pixel in wide-area OAWRS images. Employing Kullback–Leibler divergence or the relative entropy in bits from Information Theory is shown to also enable automatic discrimination of fish from seafloor by their distinct statistical scattering properties across sensing frequency, but without the statistical optimal properties of the Neyman–Pearson approach.
Journal Article
HaCeD-Seq: a Novel Method for Reliable and Easy Estimation About the Fish Population Using Haplotype Count from eDNA
It is common to count the numbers of specified fish in the field after speciation of captured fish according to their morphology and to subject these counts to appropriate statistical analyses. In recent years, a non-invasive method to estimate the abundance of a particular fish species using environmental DNA (eDNA) has been developed. However, it is still difficult to determine accurate numbers of fish species using such method. We predict that the estimation of individuals of certain fish species in the field is more accurate and easier by using haplotypes of DNA in the fast evolutionary region. Therefore, we focused on the regulatory region (D-loop) in mitochondrial DNA, which is known to have a high genetic variation at the intraspecific level of the targeting eel. We investigated haplotype diversity in eel at first and then determined the number of D-loop haplotypes contained in their exfoliated cells in breeding water. Finally, we developed a novel analytical method, HaCeD-Seq, to estimate the number of individuals based on the abovementioned data.
Journal Article
Fish Population in the Belčišta Wetland – Risk Assessment, Prevention and Management
Belčišta wetland is the largest wetland habitat in R. of North Macedonia, located 20 km distance from Ohrid Lake and it is a relict remnant of the ancient Desaret Lake, which existed in this area since the Pliocene. This region hosts an endemic freshwater species of the Balcan Penninsula,
, which is threatened by habitat loss.
There are intentions of artificial introduction of salmonid fishes in Belčišta wetland to develop the recreative fishery and tourism in this area. Introduction and spread of salmonids is a great risk factor to the survival of the ohrid minnows
).
Journal Article
Droplet digital PCR applied to environmental DNA, a promising method to estimate fish population abundance from humic‐rich aquatic ecosystems
Measures of environmental DNA (eDNA) concentrations in water samples have the potential to be both a cost‐efficient and a nondestructive method to estimate fish population abundance. However, the inherent temporal and spatial variability in abiotic and biotic conditions in aquatic systems have been suggested to be a major obstacle to determine relationships between fish eDNA concentrations and fish population abundance. Moreover, once water samples are collected, methodological biases are common, which introduces additional sources of variation to potential relationships between eDNA concentrations and fish population abundance. Here, we evaluate the performance of applying the droplet digital PCR (ddPCR) method to estimate fish population abundance in experimental enclosures. Using large‐scale enclosure ecosystems that contain populations of nine‐spined stickleback (Pungitius pungitius), we compared the concentrations of fish eDNA (COI mitochondrial region, 134 bp) obtained with the ddPCR method with high precision estimates of fish population abundance (i.e., number of individuals) and biomass. To evaluate the effects of contrasted concentrations of humic substances (potential PCR inhibitors) on the performance of ddPCR assays, we manipulated natural dissolved organic carbon (DOC) concentrations (range 4–11 mg/L) in the enclosures. Additionally, water temperature (+2°C) was manipulated in half of the enclosures. Results showed positive relationships between eDNA concentration and fish abundance and biomass estimates although unexplained variation remained. Still and importantly, fish eDNA estimates from high DOC enclosures were not lowered by potential inhibitory effects with our procedure. Finally, water temperature (although only 2°C difference) was neither detected as a significant factor influencing fish eDNA estimates. Altogether, our work highlights that ddPCR‐based eDNA is a promising method for future quantification of fish population abundance in natural systems.
We evaluated the performance of applying the droplet digital PCR (ddPCR) method to estimate fish abundance in experimental enclosures. Significant positive relationships between eDNA concentration and fish abundance and biomass were found. Additionally, fish eDNA estimates from high DOC enclosures were not lowered by potential inhibitory effects.
Journal Article