scholarly journals Can dams affect the trophic structure of ichthyofauna? A long-term effects in the Neotropical region

2018 ◽  
Vol 108 (0) ◽  
Author(s):  
Felipe P. de Lima ◽  
André B. Nobile ◽  
Diogo Freitas-Souza ◽  
Edmir D. Carvalho ◽  
Ana P. Vidotto-Magnoni
Keyword(s):  
Power Plants ◽  
Trophic Structure ◽  
Fish Assemblages ◽  
Feeding Activity ◽  
Fish Fauna ◽  
Neotropical Region ◽  
Hydroelectric Power ◽  
Long Term Effects ◽  
Aquatic Communities

ABSTRACT Dams are considered an important source of modification upon the structure of aquatic communities and their reflexes are diverse on the fish fauna. Although there are several hydroelectric power plants in Brazil, the long-term effects on feeding activity of ichthyofauna are unknown. Thus, this study aimed to investigate the long-term effects of an old reservoir (fifty years) on the trophic dynamics of fish fauna. The diet of 20 fish species was analyzed, identifying 37 food items belonging to six trophic categories, which enable to create six trophic groups. The results found here suggests that throughout the creation of a reservoir, the trophic structure of the fish assemblages tend to reach trophic homeostasis, in which the fish community will be capable of exploring the most available food resources being maintained primarily by the items placed in the categories organic matter and fragments of fish and vegetal.

Change in the rocky reef fish fauna of the iconic Poor Knights Islands Marine Reserve in north-eastern New Zealand over 4 decades

2018 ◽  
Vol 69 (10) ◽  
pp. 1496
Author(s):  
David R. Schiel ◽  
Tony Ayling ◽  
Michael J. Kingsford ◽  
Christopher N. Battershill ◽  
J. Howard Choat ◽  
...  
Keyword(s):  
Reef Fish ◽  
Fish Species ◽  
Marine Reserve ◽  
Fish Fauna ◽  
Rocky Reef ◽  
Long Term Effects ◽  
Before And After ◽  
Negative Effect ◽  
Reef Fish Species

Marine reserves exhibit increases in targeted fish species, but long-term effects on biodiversity are poorly understood. Factors other than reserve status may affect decadal changes, including environmental change. We examined the fish fauna at the iconic Poor Knights Islands over 4 decades (1974–2016) before and after implementation of a no-take marine reserve in 1998. We document a substantial increase in commercially and recreationally targeted Chrysophrys auratus, which was virtually absent before 1994 but by 2016 had reached up to 11 fish per 500m2 (220 per hectare). There were also large changes to the fish community, including the decline of subtropical and coastal wrasses, some species with no change and others that increased significantly. Many declines occurred >20 years before the arrival of abundant C. auratus, suggesting the changes do not represent a trophic cascade. Furthermore, this normally benthic-feeding fish has adopted a mid-water foraging behaviour targeting planktivorous fish. The increase in C. auratus appears to be linked both to reserve status and catch regulations in the wider region. Overall, the data point to long-term environmental fluctuations from the late 1970s having a negative effect on the abundance of more than half the reef fish species at these islands.

From Catastrophe to Recovery: Stories of Fishery Management Success

2019 ◽  
Keyword(s):  
Power Plants ◽  
Fishery Management ◽  
High Price ◽  
Hydroelectric Power ◽  
The Caspian Sea ◽  
Illegal Fishing ◽  
Conservation Measures ◽  
History Of ◽  
Commercially Important

<i>Abstract.</i>—This chapter provides the history of the Caspian Kutum <i>Rutilus kutum</i> (Kamensky 1901) fishery in the Caspian Sea, analyzes long-term changes of stock condition and the main causes of fluctuations in abundance, and describes conservation measures that allowed resumption of fishing. Caspian Kutum (Cyprinidae family) is an endemic, semi-anadromous, medium-sized fish, reaching 53–67 cm in total length (rarely 71 cm) and weighing up to 4.0 kg (rarely 5.0 kg). Commercially important fisheries occur in Russia, Azerbaijan, Iran, and Turkmenistan. Flesh and roe are enjoyed as food and have a high price in markets. Variability in sea level, construction of hydroelectric power plants on rivers, water irrigation withdrawals, industrial and domestic pollution, overfishing, and illegal fishing resulted in a sharp decline of Caspian Kutum abundance and resulted in a total ban on harvest in Russia between 1995 and 2004. In Iran, fishing for Caspian Kutum continued due to their stocking program. Conservation measures for Caspian Kutum stocks (e.g., listing in federal and local Red Data books, fishing ban, fight against illegal fishing), as well as an increase of artificial propagation in Iran, Azerbaijan, and Dagestan (Russia) during subsequent years, have allowed the recovery of stocks in Russian waters to 1990s levels as well as the resumption of fishing. The follow lessons may be applicable to fishery management programs elsewhere:

Long-Term Effects of Diet on the Biology of the Lake Trout and the Fishery in Lake Opeongo, Ontario

1970 ◽  
Vol 27 (1) ◽  
pp. 125-146 ◽  
Author(s):  
N. V. Martin
Keyword(s):  
Lake Trout ◽  
Feeding Activity ◽  
Salvelinus Namaycush ◽  
Point Of View ◽  
Average Weight ◽  
Coregonus Clupeaformis ◽  
Long Term Effects ◽  
Food Content ◽  
Coregonus Artedii

From 1936 to 1965 food content was examined in 17,171 Lake Opeongo lake trout (Salvelinus namaycush). The diet is analysed from the point of view of frequency of occurrence of foods, their weight, feeding activity of trout, size of trout and size of food, and seasonal and annual changes in food habits.In the late 1940's and early 1950's perch, Perca flavescens, largely disappeared from the diet. The lake trout initially turned to lake whitefish, Coregonus clupeaformis, and then to the cisco, Coregonus artedii, introduced into Lake Opeongo in 1948.As a result of these dietary changes lake trout are now heavier and rate of growth has improved. Age and size at maturity is later and there are fewer infertile fish. Egg counts, egg size, and ovary weights are now greater, particularly in the medium-sized lake trout.In the fishery the average weight of individual trout taken has almost doubled. About 25% more of the immature stock is exploited by the recent fishery. The harvest and catchability of lake trout has remained generally constant on a numerical basis but show an improvement on a poundage basis in the more recent years. The possible effects of these changes on the character of the fishery are discussed.

scholarly journals Dams and the fish fauna of the Neotropical region: impacts and management related to diversity and fisheries

2008 ◽  
Vol 68 (4 suppl) ◽  
pp. 1119-1132 ◽  
Author(s):  
AA. Agostinho ◽  
FM. Pelicice ◽  
LC. Gomes
Keyword(s):  
Fish Assemblages ◽  
Fish Fauna ◽  
Neotropical Region ◽  
Life Cycles ◽  
Fish Diversity ◽  
Negative Consequences ◽  
Long Distance ◽  
Management Actions ◽  
Composition And Structure ◽  
Almost All

Reservoirs have been built in almost all of the hydrographic basins of Brazil. Their purposes include water supply for cities, irrigation and mainly, generation of electricity. There are more than 700 large dams and associated reservoirs in the large rivers of the country. These reservoirs favor local and regional economic development, but they also bring serious and irreversible alterations in the natural hydrologic regime of rivers, affecting habitat quality and the dynamics of the biota. In the impounded area, the main impact is the change from lotic to lentic water, which influences aquatic fauna, including fishes. Impacts of reservoirs present relevant spatiotemporal variations. Immediately after reservoir formation, fish species richness usually increases due to incorporation of surrounding habitats, but richness decreases as reservoirs age. However, impacts downstream of dams appear to be similar or stronger than those that occur within the reservoir. Dams promote discharge control, altering the seasonal cycles of floods. These effects are augmented when dams are constructed in cascades. Therefore, dams profoundly influence composition and structure of fish assemblages. Most affected species are the rheophilics and long distance migratory that require distinct habitats to fulfill their life cycles. Populations of migratory species may collapse or even disappear in intensely regulated stretches. Management actions taken to minimize impacts of dams in Brazil historically considered construction of fish passages, fishery control and stocking. The results of these actions are questionable and/or with clear failures. In this paper, we give emphasis to the Paraná River basin, the most affected by dams in Brazil. We describe some patterns in the alteration and decline in fish diversity in areas influenced by dams. We also discuss negative consequences in the fishery and ecosystems functioning. Finally, we argue the relevance and the success of the management actions taken and present some suggestions to improve conservation of the ichthyofauna in South American basins influenced by dams.

scholarly journals The Amur River Water During the Winter Low-water Period: The Many-year dynamics of the Sulfates Content and Runoff.

2020 ◽  
pp. 82-93
Author(s):  
Keyword(s):  
Power Plants ◽  
Hydroelectric Power ◽  
Amur Basin ◽  
Amur River ◽  
Economic Changes ◽  
Large Cities ◽  
The Amur River ◽  
The Many ◽  
The Impact

ulfates are the dominant ions among the major ones in the Amur region’s sewage. Therefore, the purpose of the research is to study the long-term dynamics of the content and runoff of sulfates in the Amur River in the winter low-water, based on the materials of Roshydromet for 1943-1976 and the author’s data for 1999-2019.Significant variations in the main areas were found due to both the diversity of natural conditions and anthropogenic influence in the areas of large cities and localities. The impact of the construction of hydroelectric power plants, significant economic changes in the Chinese part of the Amur basin, as well as the closure of pulp and paper and microbiological industries in the Russian part of the Amur basin on the long-term dynamics of the content and flow of sulfates is estimated. The maximum content of sulfates in the Amur River was observed after the accident at the Jilin chemical plant in China in December 2005. The influence of major floods on the increase in the flow of sulphates in the winter low-water was established.

Age-Related Degradation of Steam Generator Internals Based on Industry Responses to Generic Letter 97-06

2002 ◽  
Author(s):  
M. Subudhi ◽  
E. J. Sullivan
Keyword(s):  
Steam Generator ◽  
Nuclear Power ◽  
Power Plants ◽  
Pressurized Water Reactor ◽  
Long Term Effects ◽  
Steam Generators ◽  
Pressurized Water ◽  
Age Related ◽  
The U.S

This paper presents the results of an aging assessment of the nuclear power industry’s responses to NRC Generic Letter 97-06 on the degradation of steam generator internals experienced at Electricite de France (EdF) plants in France and at a United States pressurized water reactor (PWR). Westinghouse (W), Combustion Engineering (CE), and Babcock & Wilcox (B & W) steam generator models, currently in service at U.S. nuclear power plants, potentially could experience degradation similar to that found at EdF plants and the U.S. plant. The steam generators in many of the U.S. PWRs have been replaced with steam generators with improved designs and materials. These replacement steam generators have been manufactured in the U.S. and abroad. During this assessment, each of the three owners groups (W, CE, and B&W) identified for its steam generator models all the potential internal components that are vulnerable to degradation while in service. Each owners group developed inspection and monitoring guidance and recommendations for its particular steam generator models. The Nuclear Energy Institute incorporated in NEI 97-06, “Steam Generator Program Guidelines,” a requirement to monitor secondary side steam generator components if their failure could prevent the steam generator from fulfilling its intended safety-related function. Licensees indicated that they implemented or planned to implement, as appropriate for their steam generators, their owners group recommendations to address the long-term effects of the potential degradation mechanisms associated with the steam generator internals.

Holocene fish assemblages provide baseline data for the rapidly changing eastern Mediterranean

The Holocene ◽  
2020 ◽  
Vol 30 (10) ◽  
pp. 1438-1450
Author(s):  
Konstantina Agiadi ◽  
Paolo G Albano
Keyword(s):  
Radiocarbon Dating ◽  
Trophic Structure ◽  
Fish Assemblages ◽  
Eastern Mediterranean ◽  
Marine Ecosystem ◽  
Fish Fauna ◽  
Suez Canal ◽  
Indigenous Species ◽  
The Mediterranean ◽  
Non Indigenous Species

The eastern Mediterranean marine ecosystem is undergoing massive modification due to biological invasions, overfishing, habitat deterioration, and climate warming. Our ability to quantify these changes is severely hindered by the lack of an appropriate baseline; most ecological datasets date back a few decades only and show already strong signatures of impact. Surficial death assemblages (DAs) offer an alternative data source that provides baseline information on community structure and composition. In this study, we reconstruct the marine fish fauna of the southern shallow Israeli shelf before the opening of the Suez Canal based on fish otoliths. We quantify the age of the otolith DAs by radiocarbon dating, and describe its taxonomic composition, geographic affinity, and trophic structure. Additionally, we test by radiocarbon dating the hypothesis that Bregmaceros, a presumed Lessepsian invader with continuous presence in the Mediterranean throughout the late Cenozoic, is a relict species. The otolith DA dates back to the mid-Holocene because 75% of the dated otoliths of the native species are older than the opening of the Suez Canal in 1869, suggesting that the DA is a proper baseline for quantifying modern impacts. Consistently, 97% of the otoliths and 88% of the species we collected belong to native Mediterranean species. The native anchovy Engraulis encrasicolus dominates the DAs, although gobiids are the most diverse group (14 species, 28%). The DAs show similar trophic structure to present-day pristine Mediterranean coastal fish assemblages. Two non-indigenous species are recorded here for the first time in the Mediterranean Sea, Amblygobius albimaculatus and Callogobius sp., highlighting the importance of DAs for detecting non-indigenous species. Finally, Bregmaceros otoliths are modern, not supporting the previous hypothesis that the taxon is a Pleistocene relict.

Development and Stability of Fish Assemblages after Lime Treatment

1991 ◽  
Vol 48 (4) ◽  
pp. 546-554 ◽  
Author(s):  
Magnus Appelberg ◽  
Erik Degerman
Keyword(s):  
Species Interactions ◽  
Fish Assemblages ◽  
Negative Relationship ◽  
Habitat Diversity ◽  
Long Term Effects ◽  
Lime Treatment ◽  
Physical And Chemical Variables ◽  
Physical And Chemical ◽  
Species Proportions

Long-term effects of limestone treatment on fish populations in acidified lakes in Sweden have been examined since 1983 to assess the development and stability of fish assemblages after lime treatment. In total, 77 lakes were sampled twice using standardized methods between 1983 and 1988. The lakes were limed 1–16 yr before the second sampling. Physical and chemical variables and the fish data were reduced using PCA ordination and the resulting relationships were analyzed using linear regression and ANOVA. Relationships between the fish assemblage characteristics and the environmental factors were highly dependent on the species composition of the assemblages. The number and diversity of fish species were correlated with both the extent of acidification and habitat diversity of the lakes. The importance of species interactions after lime treatment was suggested by a negative relationship between changes in the scores of community along the first component of the fish PCA and changes along two of the other species components between the two samplings. Despite a weak tendency towards reduced variability in species proportions as time passed since the first liming, the development of community stability, expressed as lack of change in species proportions, was insignificant.

scholarly journals Comparative analysis of renewable energy development in the Republic of Buryatia (Russia) and Mongolia

2021 ◽  
Vol 885 (1) ◽  
pp. 012015
Author(s):  
A G Badmaev
Keyword(s):  
Alternative Energy ◽  
Power Plants ◽  
Green Energy ◽  
Fuel Oil ◽  
Hydroelectric Power ◽  
Coal Fuel ◽  
Infrastructure Investments ◽  
The Republic ◽  
Low Efficiency

Abstract The constantly growing demand for electricity and relatively small energy capacities are forcing the Republic of Buryatia (to a greater extent) and Mongolia, which are limited in some types of economic activity, to look for new sources of energy. One of these restrictions is the ban on the construction of hydroelectric power plants on rivers of the Lake Baikal basin. Therefore, Buryatia and Mongolia have taken the path of building environmentally friendly power plants and have succeeded in many ways. Despite the high costs of setting up clean power plants, infrastructure investments in alternative energy are long-term and expected to be profitable. Investors (including foreign ones) placing their money in a seemingly low-profit project, having long-term expectations. Competent investors do not run after “quick money”, realising that the return period of the constructed power plants will be long, as at the moment of development they have a relatively low efficiency. Despite the criticism of some researchers [1], they invest in green energy, modern infrastructure and a future without emissions (CO2, NO2, SO2 and other gases) from burning coal, fuel oil and firewood. Other experts see in the development of alternative energy a great potential [2-5], refuting arguments of critics about high cost of electricity [6].

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