Changes in species composition of the demersal fish community in nearshore waters of Kodiak Island, Alaska

2000 ◽  
Vol 57 (6) ◽  
pp. 1169-1180 ◽  
Author(s):  
Franz J Mueter ◽  
Brenda L Norcross
Keyword(s):  
Species Composition ◽  
Major Part ◽  
Fish Community ◽  
Demersal Fish ◽  
Trawl Survey ◽  
Data Set ◽  
Forage Fishes ◽  
Kodiak Island ◽  
Trends Over Time ◽  
Over Time

We examined the species composition of the demersal fish and shrimp community in seven different areas in the nearshore waters of Kodiak Island based on trawl survey data. A major part of the variability in the data set was attributed to trends over time, indicating a significant change in species composition in the early 1980s. Results agree with work by others and show a shift from a community dominated by shrimp and small forage fishes to one dominated by large piscivorous gadid and flatfish species. The shift occurred rather abruptly in most areas between 1980 and 1982, but the pattern of change differed significantly among areas. Correlations between trends in the two groups of species were weak but were consistent with the hypothesis that the decline in shrimp and forage fishes followed, rather than preceded, the increase in large piscivorous fishes. The results suggest predation as a possible mechanism to explain the observed changes.

US academic libraries' staffing and expenditure trends (1996–2016)

2020 ◽  
Vol 41 (4/5) ◽  
pp. 247-268 ◽  
Author(s):  
Starr Hoffman ◽  
Samantha Godbey
Keyword(s):  
Academic Libraries ◽  
The United States ◽  
Data Sets ◽  
Size Category ◽  
Data Set ◽  
Content Type ◽  
Education Statistics ◽  
Trends Over Time ◽  
Doctoral Institutions ◽  
Over Time

PurposeThis paper explores trends over time in library staffing and staffing expenditures among two- and four-year colleges and universities in the United States.Design/methodology/approachResearchers merged and analyzed data from 1996 to 2016 from the National Center for Education Statistics for over 3,500 libraries at postsecondary institutions. This study is primarily descriptive in nature and addresses the research questions: How do staffing trends in academic libraries over this period of time relate to Carnegie classification and institution size? How do trends in library staffing expenditures over this period of time correspond to these same variables?FindingsAcross all institutions, on average, total library staff decreased from 1998 to 2012. Numbers of librarians declined at master’s and doctoral institutions between 1998 and 2016. Numbers of students per librarian increased over time in each Carnegie and size category. Average inflation-adjusted staffing expenditures have remained steady for master's, baccalaureate and associate's institutions. Salaries as a percent of library budget decreased only among doctoral institutions and institutions with 20,000 or more students.Originality/valueThis is a valuable study of trends over time, which has been difficult without downloading and merging separate data sets from multiple government sources. As a result, few studies have taken such an approach to this data. Consequently, institutions and libraries are making decisions about resource allocation based on only a fraction of the available data. Academic libraries can use this study and the resulting data set to benchmark key staffing characteristics.

Temporal changes in a demersal fish and cephalopod community of an unexploited coastal area in Northern Australia

1984 ◽  
Vol 35 (6) ◽  
pp. 747 ◽  
Author(s):  
SF Rainer
Keyword(s):  
Water Temperature ◽  
Seasonal Changes ◽  
Fish Community ◽  
Demersal Fish ◽  
Temporal Changes ◽  
Tropical Fish ◽  
Trawl Survey ◽  
Depth Range ◽  
Local Abundance ◽  
Different Seasons

A trawl survey of the south-eastern Gulf of Carpentaria carried out at the beginning of a commercial prawn fishery in the 1960s provided data on the demersal fish of an unexploited tropical fish community. The extent of temporal variation in this community was investigated using abundance data on 359 taxa of fish and cephalopods over 13 months in 1963-1964. Seasonal changes in water temperature and salinity were large, particularly in nearshore waters. Catch rates and species richness in nearshore waters were highest during summer, and in offshore waters during autumn or winter. Shannon diversity was variable, with no clear seasonal component. Temporal changes in community composition resulted in large changes between different seasons in the structure of site groups derived by classification; temporal effects within seasons were also found. The numerically dominant species were the leatherjackets Paramonacanthus spp., the ponyfish Equulites leuciscus, the tripodfish Tripodichthys blochii, and the saury Saurida undosquamis. Squid, the ponyfish Leiognathus sp. nr blochi, the butterfly-bream Nemipterus tolu and the grunter Pomadasys maculatus were seasonally abundant. Although species were restricted in their depth range, discrete communities that maintained their identity in different seasons were apparently absent. The relative abundance of many species varied substantially wirh season and probably also over a longer period. Small changes in local abundance were often associated with movement to deeper water at times of high nearshore water temperature (summer) or of reduced nearshore salinity (autumn). Large seasonal changes occurred in the local abundance of estuarine and semidiadromous species. The community shared many species with the demersal fish community of the Gulf of Thailand. It is suggested that similar structural changes in the fish community of the Gulf of Carpentaria may occur in response to intensive fishing. Further research on the effects of demersal fishing and on the interactions of the demersal fish community with commercially important crustaceans is necessary.

Long-term changes of epiphytic lichen species composition over landscape gradients: an 18 year time series

2008 ◽  
Vol 40 (05) ◽  
pp. 437-448 ◽  
Author(s):  
Jiří LIŠKA ◽  
Tomáš HERBEN
Keyword(s):  
Air Pollution ◽  
Species Composition ◽  
Pollution Sources ◽  
Rate Of Change ◽  
Lichen Species ◽  
Tree Bark ◽  
Data Set ◽  
Local Conditions ◽  
Epiphytic Lichen ◽  
Over Time

Abstract:The study aimed to determine how the response of the epiphytic lichen vegetation to sulphur air pollution is affected by interaction with other factors (distance from pollution sources, habitat, altitude, initial eutrophication of the tree bark). It was based on a series of four successive recordings taken over a period of 18 years with increasing pollution levels and on the same set of 139 solitary trees. Relationships between habitat variables and lichen community composition are assessed using canonical correspondence analysis. The data set comprised 69 lichen species. Ordination of initial species composition on trees revealed two major gradients: eutrophication and acidity.The species composition significantly changed with time, with a general decrease of the total number of lichen species per tree. In general, species sensitive to air pollution decreased, while tolerant species increased in number. Change over time differed depending on the position of the tree within the landscape (relative to one major source of pollution, the town of Tábor, whereas the distance to the other source, Sezimovo Ústí, was not significant) and on the initial species composition found on the tree. Trees under the effect of eutrophication changed their species composition less, indicating that the effect of eutrophication (mainly increased bark pH) may ameliorate the effects of air pollution; a local effect of eutrophication also seems to play an important role. Distance to pollution sources had only a small impact on the rate of change and perhaps other local conditions (sheltered or humid position, altitude) play a role in this interaction. There was a decrease of the overall heterogeneity of the data set over time. This means that the gradients in species composition attributable to these variables became less important over time. Therefore, one of the effects of air pollution is also a general homogenization of the lichen vegetation of the solitary trees.

The Presidents’ Orders

2017 ◽  
Author(s):  
Michelle Belco ◽  
Brandon Rottinghaus
Keyword(s):  
Data Set ◽  
Executive Orders ◽  
Trends Over Time ◽  
Over Time

Chapter 3 describes the data collected and evaluates the trends over time. The data include executive orders and proclamations, the two most prominent types of unilateral orders. The data set includes a total of more than 2,400 unilateral orders issued from President Gerald Ford to President George W. Bush from 1974 to 2009.

scholarly journals Survey Nonresponse Trends and Fieldwork Effort in the 21st Century: Results of an International Study across Countries and Surveys

2020 ◽  
Vol 36 (3) ◽  
pp. 469-487 ◽  
Author(s):  
Annemieke Luiten ◽  
Joop Hox ◽  
Edith de Leeuw
Keyword(s):  
Survey Design ◽  
International Study ◽  
Response Rates ◽  
Data Set ◽  
Survey Nonresponse ◽  
Present Trend ◽  
Trend Data ◽  
Trends Over Time ◽  
International Comparative ◽  
Over Time

AbstractFor more than three decades, declining response rates have been of concern to both survey methodologists and practitioners. Still, international comparative studies have been scarce. In one of the first international trend analyses for the period 1980–1997, De Leeuw and De Heer (2002) describe that response rates declined over the years and that countries differed in response rates and nonresponse trends. In this article, we continued where De Leeuw and De Heer (2002) stopped, and present trend data for the next period 1998–2015 from National Statistical Institutes. When we looked at trends over time in this new data set, we found that response rates are still declining over the years. Furthermore, nonresponse trends do differ over countries, but not over surveys. Some countries show a steeper decline in response than others, but all types of surveys show the same downward trend. The differences in (non)response trends over countries can be partly explained by differences in survey design between the countries. Finally, for some countries cost indicators were available, these showed that costs increased over the years and are negatively correlated with noncontact rates.

Dissolved oxygen and temperature best predict deep-sea fish community structure in the Gulf of California with climate change implications

2020 ◽  
Vol 637 ◽  
pp. 159-180
Author(s):  
ND Gallo ◽  
M Beckwith ◽  
CL Wei ◽  
LA Levin ◽  
L Kuhnz ◽  
...  
Keyword(s):  
Climate Change ◽  
Community Structure ◽  
Community Composition ◽  
Environmental Conditions ◽  
Deep Sea ◽  
Gulf Of California ◽  
Fish Community ◽  
Demersal Fish ◽  
Fish Community Structure ◽  
Explained Variance

Natural gradient systems can be used to examine the vulnerability of deep-sea communities to climate change. The Gulf of California presents an ideal system for examining relationships between faunal patterns and environmental conditions of deep-sea communities because deep-sea conditions change from warm and oxygen-rich in the north to cold and severely hypoxic in the south. The Monterey Bay Aquarium Research Institute (MBARI) remotely operated vehicle (ROV) ‘Doc Ricketts’ was used to conduct seafloor video transects at depths of ~200-1400 m in the northern, central, and southern Gulf. The community composition, density, and diversity of demersal fish assemblages were compared to environmental conditions. We tested the hypothesis that climate-relevant variables (temperature, oxygen, and primary production) have more explanatory power than static variables (latitude, depth, and benthic substrate) in explaining variation in fish community structure. Temperature best explained variance in density, while oxygen best explained variance in diversity and community composition. Both density and diversity declined with decreasing oxygen, but diversity declined at a higher oxygen threshold (~7 µmol kg-1). Remarkably, high-density fish communities were observed living under suboxic conditions (<5 µmol kg-1). Using an Earth systems global climate model forced under an RCP8.5 scenario, we found that by 2081-2100, the entire Gulf of California seafloor is expected to experience a mean temperature increase of 1.08 ± 1.07°C and modest deoxygenation. The projected changes in temperature and oxygen are expected to be accompanied by reduced diversity and related changes in deep-sea demersal fish communities.

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