Large-scale changes in the littoral fish communities of lakes in southeastern Ontario, Canada

2018 ◽  
Vol 96 (7) ◽  
pp. 753-759
Author(s):  
Paul A. Finigan ◽  
Nicholas E. Mandrak ◽  
Bruce L. Tufts
Keyword(s):  
Fish Community ◽  
Large Scale ◽  
Historical Data ◽  
Fish Communities ◽  
Biodiversity Loss ◽  
Data Sets ◽  
Inland Lakes ◽  
Biodiversity Change ◽  
North American Freshwater Fish ◽  
Management Approaches

Biodiversity loss is a serious issue for freshwater fishes in temperate climates and there is a need for more information in this area. A study was conducted to assess fish community changes in the littoral zone of 22 lakes over a 45 year period (compared years 1969–1979 and year 2014). To compare fish communities, historical seining records were compiled for 22 inland lakes and compared with contemporary data sampled using the same protocol. Fish abundance data analyzed using a multivariate approach identified a shift from cyprinid-dominated communities to centrarchid-dominated communities between time periods. There was no evidence to support a strong influence of invasive species on these communities, but there have been significant changes in temperature and land use around these lakes since the historical data sets were collected. This is an important contribution to our understanding of biodiversity change in North American freshwater fish communities and may influence fisheries management approaches in the future.

scholarly journals Long-term shift in coastal fish communities before and after the collapse of Atlantic cod (Gadus morhua)

2015 ◽  
Vol 73 (5) ◽  
pp. 1415-1426 ◽  
Author(s):  
J. Scott P. McCain ◽  
Deneen J. Cull ◽  
David C. Schneider ◽  
Heike K. Lotze
Keyword(s):  
Fish Community ◽  
Large Scale ◽  
Gadus Morhua ◽  
Atlantic Cod ◽  
Substantial Reduction ◽  
Fish Communities ◽  
Coastal Habitat ◽  
Coastal Fish ◽  
Before And After

Abstract The collapse of the Northwest Atlantic cod (Gadus morhua) stocks in the early 1990s led to widespread ecological changes offshore. Changes in coastal fish communities are less known, largely due to the lack of historical records and long-term, standardized research surveys in coastal ecosystems. We aimed to overcome this with a unique dataset known as the Fleming survey. From 1959 to 1964, a systematic beach-seine survey was conducted to examine juvenile cod abundance in 84 bays (42 of which were consistently sampled and therefore analysed) along the east coast of Newfoundland. In addition to cod, all other fish collected in the seines were recorded. These surveys were repeated from 1992 to 1996 after the cod collapse, and document a substantial reduction in a dominant inshore species—juvenile Atlantic cod. We show that total fish abundance declined significantly with the decrease of cod, whereas Shannon diversity and species evenness significantly increased. Species richness increased in some regions but decreased in others. We also found significant changes in the composition of the fish community likely due to a combination of release from predation from fewer large cod feeding in inshore areas as well as a release from competition from fewer juvenile cod occupying the coastal habitat. Region and the presence of vegetated habitats also significantly influenced the fish community. This study shows a strong reorganization of coastal fish communities after a large-scale fisheries collapse with implications for ecosystem-based and cross-ecosystem management.

scholarly journals Complementarity, completeness and quality of long-term faunal archives in an Asian biodiversity hotspot

2019 ◽  
Vol 374 (1788) ◽  
pp. 20190217 ◽  
Author(s):  
Samuel T. Turvey ◽  
Connor Walsh ◽  
James P. Hansford ◽  
Jennifer J. Crees ◽  
Jon Bielby ◽  
...  
Keyword(s):  
Large Scale ◽  
Research Priorities ◽  
Hainan Island ◽  
Biodiversity Loss ◽  
High Elevation ◽  
Faunal Turnover ◽  
The Past ◽  
Biodiversity Change

Long-term baselines on biodiversity change through time are crucial to inform conservation decision-making in biodiversity hotspots, but environmental archives remain unavailable for many regions. Extensive palaeontological, zooarchaeological and historical records and indigenous knowledge about past environmental conditions exist for China, a megadiverse country experiencing large-scale biodiversity loss, but their potential to understand past human-caused faunal turnover is not fully assessed. We investigate a series of complementary environmental archives to evaluate the quality of the Holocene–historical faunal record of Hainan Island, China's southernmost province, for establishing new baselines on postglacial mammalian diversity and extinction dynamics. Synthesis of multiple archives provides an integrated model of long-term biodiversity change, revealing that Hainan has experienced protracted and ongoing human-caused depletion of its mammal fauna from prehistory to the present, and that past baselines can inform practical conservation management. However, China's Holocene–historical archives exhibit substantial incompleteness and bias at regional and country-wide scales, with limited taxonomic representation especially for small-bodied species, and poor sampling of high-elevation landscapes facing current-day climate change risks. Establishing a clearer understanding of the quality of environmental archives in threatened ecoregions, and their ability to provide a meaningful understanding of the past, is needed to identify future conservation-relevant historical research priorities. This article is part of a discussion meeting issue ‘The past is a foreign country: how much can the fossil record actually inform conservation?’

scholarly journals Initial recovery of demersal fish communities in coastal waters of Hong Kong, South China, following a trawl ban

2021 ◽  
Author(s):  
Yanny K. Y. Mak ◽  
Lily S. R. Tao ◽  
Valerie C. M. Ho ◽  
David Dudgeon ◽  
William W. L. Cheung ◽  
...  
Keyword(s):  
Hong Kong ◽  
Coastal Waters ◽  
Fish Community ◽  
Large Scale ◽  
Fish Communities ◽  
Recovery Process ◽  
Anthropogenic Disturbances ◽  
Marine Habitat ◽  
Fisheries Resources ◽  
Initial Recovery

Abstract Fisheries resources in Hong Kong have been overexploited since the 1970s due to intensive bottom trawling and other fishing activities that have depleted stocks and destroyed marine habitat. To rehabilitate depleted fisheries resources, a permanent ban on trawling in Hong Kong territorial waters came into force on December 31, 2012. In order to determine whether the trawl facilitated recovery of fish communities, trawl surveys were conducted at two sites in each of the eastern, southern and western (estuarine) coastal waters of Hong Kong before and three years after the trawl ban. A total of 315 species and 86 families of fishes in nine feeding groups were encountered during the surveys. Mean trophic level of the fish community, abundance and biomass of total fishes and of predatory fishes increased in eastern and western waters after the ban, but no changes or declines in these metrics were observed in southern waters. Although initial recovery in fish community were observed in eastern and western waters, anthropogenic disturbances might hinder the recovery process, including a large-scale reclamation for construction of coastal infrastructures in the west, illegal trawling, and expansion of non-trawling fishing efforts in the southern and eastern waters. Longer term monitoring is needed to evaluate the effects of the trawl ban, and determine whether recovery in the southern waters will continue to be constrained by the anthropogenic disturbances. Graphic abstract

scholarly journals Twentieth century turnover of Mexican endemic avifaunas: Landscape change versus climate drivers

2015 ◽  
Vol 1 (4) ◽  
pp. e1400071 ◽  
Author(s):  
A. Townsend Peterson ◽  
Adolfo G. Navarro-Sigüenza ◽  
Enrique Martínez-Meyer ◽  
Angela P. Cuervo-Robayo ◽  
Humberto Berlanga ◽  
...  
Keyword(s):  
Land Use ◽  
Large Scale ◽  
Bird Species ◽  
Data Sets ◽  
Ecological Communities ◽  
Biodiversity Data ◽  
Climate Change Effects ◽  
Coarse Spatial Resolution ◽  
Biodiversity Change ◽  
Gains And Losses

Numerous climate change effects on biodiversity have been anticipated and documented, including extinctions, range shifts, phenological shifts, and breakdown of interactions in ecological communities, yet the relative balance of different climate drivers and their relationships to other agents of global change (for example, land use and land-use change) remains relatively poorly understood. This study integrated historical and current biodiversity data on distributions of 115 Mexican endemic bird species to document areas of concentrated gains and losses of species in local communities, and then related those changes to climate and land-use drivers. Of all drivers examined, at this relatively coarse spatial resolution, only temperature change had significant impacts on avifaunal turnover; neither precipitation change nor human impact on landscapes had detectable effects. This study, conducted across species’ geographic distributions, and covering all of Mexico, thanks to two large-scale biodiversity data sets, could discern relative importance of specific climatic drivers of biodiversity change.

Dominance determines fish community biomass in a temperate seagrass ecosystem

2019 ◽  
Author(s):  
Aaron Matthius Eger ◽  
Rebecca J. Best ◽  
Julia Kathleen Baum
Keyword(s):  
Species Richness ◽  
Ecosystem Function ◽  
Fish Community ◽  
Prey Capture ◽  
Fish Communities ◽  
Functional Trait ◽  
Ecosystem Functions ◽  
Community Biomass ◽  
Ecosystem Valuation ◽  
Species Abundances

Biodiversity and ecosystem function are often correlated, but there are multiple hypotheses about the mechanisms underlying this relationship. Ecosystem functions such as primary or secondary production may be maximized by species richness, evenness in species abundances, or the presence or dominance of species with certain traits. Here, we combined surveys of natural fish communities (conducted in July and August, 2016) with morphological trait data to examine relationships between diversity and ecosystem function (quantified as fish community biomass) across 14 subtidal eelgrass meadows in the Northeast Pacific (54° N 130° W). We employed both taxonomic and functional trait measures of diversity to investigate if ecosystem function is driven by species diversity (complementarity hypothesis) or by the presence or dominance of species with particular trait values (selection or dominance hypotheses). After controlling for environmental variation, we found that fish community biomass is maximized when taxonomic richness and functional evenness is low, and in communities dominated by species with particular trait values – those associated with benthic habitats and prey capture. While previous work on fish communities has found that species richness is positively correlated with ecosystem function, our results instead highlight the capacity for regionally prevalent and locally dominant species to drive ecosystem function in moderately diverse communities. We discuss these alternate links between community composition and ecosystem function and consider their divergent implications for ecosystem valuation and conservation prioritization.

Community changes of coral reef fishes in Bunaken National Park, North Sulawesi, Indonesia

2013 ◽  
Vol 1 (2) ◽  
pp. 117
Author(s):  
Fakhrizal Setiawan ◽  
Janny D Kusen ◽  
Georis JF Kaligis
Keyword(s):  
Reef Fish ◽  
National Park ◽  
Fish Community ◽  
Time Series Data ◽  
Coral Cover ◽  
Fish Communities ◽  
Reef Fishes ◽  
Series Data ◽  
Fish Community Structure ◽  
Reef Fish Community

In order to look at changes in coral and reef fish communities during the period of 2006 to 2013, this research was carried out at Bunaken National Park (BNP) with 26 observation sites. The existing data and information of reef fish communities in the park generally could not be used as representative for describing the whole region. Percentage of coral cover and fish abundance during the study period shows that Bunaken Island is more similar to other locations. Reef fish community structure as seen from ecological index (H' at all sites being categorized, E category labile and low category C) shows the condition of the reef fish community is still good. Changes in the structure of reef fish communities showed declining conditions compared to 2006, and coral cover continued to decrease compared to 1998 and 2007. Good overall reef fish and coral cover have decreased; it is thought to be related to the pressure in BNP. Some of the pressures in the region were (i) increasing numbers of domestic as well as foreign visitors, (ii) increasing number of residents in the region, as well as the burden of waste and trash from the Bay of Manado. Penelitian dilakukan di Taman Nasional Bunaken (Utara dan Selatan)   pada 26 lokasi  pengamatan untuk menganalisis perubahan struktur komunitas ikan karang melalui kajian dari suatu time series data dari beberapa penelitian sebelumnya. Data primer mengenai ikan-ikan karang diperoleh melalui visual sensus bawah air yang bersamaan dengan observasi terumbu karang menggunakan point intercept transect. Nilai persentase tutupan karang dan kelimpahan ikan menunjukkan bahwa pada lokasi pengamatan Pulau Bunaken paling baik dibandingan lokasi lainnya. Struktur komunitas ikan karang yang dianalisis dengan indeks ekologi menunjukkan indeks keanekaragaman (H’) di semua site masuk kategori sedang, indeks kesamaan (E) kategori labil dan indeks Dominansi (C) kategori rendah. Hasil penelitian ini menunjukkan bahwa kondisi komunitas ikan karang masih baik, sekalipun  perubahan struktur komunitas ikan karang menunjukkan kondisi yang menurun dibandingkan tahun 2006, begitu juga tutupan karang yang terus turun dibandingkan tahun 1998 dan 2007. Secara keseluruhan baik ikan karang maupun tutupan karang mengalami penurunan, hal ini diduga terkait dengan tekanan yang dialami kawasan TN. Bunaken. Salah satu tekanan terhadap kawasan adalah jumlah turis dari dalam maupun luar negeri yang semakin meningkat tiap tahunnya, penambahan jumlah penduduk di dalam kawasan, serta beban limbah dan sampah dari Teluk Manado.

Flexible Spectrum Management: Approaches for India

2015 ◽  
Vol 8 (1) ◽  
Author(s):  
Arturo Basaure ◽  
Heikki Kokkinen ◽  
Heikki Hämmäinen ◽  
V. Sridhar
Keyword(s):  
Large Scale ◽  
Mobile Services ◽  
Radio Spectrum ◽  
Spectrum Management ◽  
Management Approach ◽  
Unlicensed Spectrum ◽  
Spectrum Band ◽  
Management Policies ◽  
Management Approaches ◽  
Lock In

Radio spectrum for commercial mobile services continues to be scarce. Countries around the world have recognized the importance of efficient utilization of this scarce resource and have initiated regulatory and policy steps towards flexible approaches to spectrum management, including sharing of licensed spectrum, and releasing unlicensed spectrum for mobile services. Technologies for shared access and the associated standardization activities have also progressed towards possible large scale deployments. In this paper, we analyze the evolution of spectrum management policies using a causal model and indicate how the markets can lock in to either centralized or flexible approach. We also cite a use case of a flexible spectrum management approach using spectrum band fill option and indicate its suitability to the Indian context.

Are local losses of biodiversity causing degraded ecosystem function?

2017 ◽  
Author(s):  
Mark Vellend
Keyword(s):  
Ecosystem Function ◽  
Species Interactions ◽  
Regional Scale ◽  
Temporal Trends ◽  
Biodiversity Loss ◽  
Large Degree ◽  
Global Scale ◽  
Degraded Ecosystem ◽  
Biodiversity Change ◽  
Local Extirpation

This chapter highlights the scale dependence of biodiversity change over time and its consequences for arguments about the instrumental value of biodiversity. While biodiversity is in decline on a global scale, the temporal trends on regional and local scales include cases of biodiversity increase, no change, and decline. Environmental change, anthropogenic or otherwise, causes both local extirpation and colonization of species, and thus turnover in species composition, but not necessarily declines in biodiversity. In some situations, such as plants at the regional scale, human-mediated colonizations have greatly outnumbered extinctions, thus causing a marked increase in species richness. Since the potential influence of biodiversity on ecosystem function and services is mediated to a large degree by local or neighborhood species interactions, these results challenge the generality of the argument that biodiversity loss is putting at risk the ecosystem service benefits people receive from nature.

Language change across a lifetime: A historical micro-perspective

2021 ◽  
Vol 7 (s2) ◽  
Author(s):  
Alexander Bergs
Keyword(s):  
Communities Of Practice ◽  
Social Factors ◽  
Language Use ◽  
Language Change ◽  
Historical Data ◽  
Data Sets ◽  
The Social ◽  
Challenges And Opportunities ◽  
Linguistic Behavior ◽  
Micro Analysis

Abstract This paper focuses on the micro-analysis of historical data, which allows us to investigate language use across the lifetime of individual speakers. Certain concepts, such as social network analysis or communities of practice, put individual speakers and their social embeddedness and dynamicity at the center of attention. This means that intra-speaker variation can be described and analyzed in quite some detail in certain historical data sets. The paper presents some exemplary empirical analyses of the diachronic linguistic behavior of individual speakers/writers in fifteenth to seventeenth century England. It discusses the social factors that influence this behavior, with an emphasis on the methodological and theoretical challenges and opportunities when investigating intra-speaker variation and change.

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