Intakes as Sampling Locations for Investigating Long-Term Trends in Zooplankton Populations

1984 ◽  
Vol 41 (10) ◽  
pp. 1513-1518 ◽  
Author(s):  
Marlene S. Evans ◽  
Loren E. Flath
Keyword(s):  
Community Structure ◽  
Power Plant ◽  
Lake Michigan ◽  
Population Estimates ◽  
Sampling Location ◽  
Water Interface ◽  
Accurate Representation ◽  
Sampling Locations ◽  
Long Term Trends

We present data demonstrating the representativeness of a power plant intake as a sampling location for investigating long-term trends in zooplankton populations. The intake (Donald C. Cook Nuclear Plant) and the inshore region (southeastern Lake Michigan) were sampled within a matter of days on 54 occasions between April 1975 and November 1981. Intake population estimates were significantly correlated with inshore region population estimates for all 26 zooplankton taxa categories analyzed. Differences in abundances in intake and inshore region samples were not significant for most euplanktonic taxa. The plant apparently entrained water and microcrustaceans from the sediment–water interface. However, because vertically hauled plankton nets do not effectively sample the lower 1 m of the water column, intake sampling may provide a more accurate representation of nearshore region copepod and cladoceran community structure than traditionally employed methods for inshore region sampling.

Historic Changes in Lake Michigan Zooplankton Community Structure: The 1960s Revisited with Implications for Top-Down Control

1992 ◽  
Vol 49 (8) ◽  
pp. 1734-1749 ◽  
Author(s):  
Marlene S. Evans
Keyword(s):  
Community Structure ◽  
Lake Michigan ◽  
Species Abundance ◽  
Zooplankton Community ◽  
Water Clarity ◽  
Phosphorus Loading ◽  
Top Down ◽  
Zooplankton Community Structure ◽  
The 1960S

Recent changes in the Lake Michigan ecosystem provide a benchmark against which to reevaluate historic data. During the 1960s, the alewife (Alosa pseudoharengus) population exploded and then crashed. Offshore zoo-plankton data for the summers of 1954, 1966, and 1968 provided evidence that variations in alewife abundance had a major effect on zooplankton community structure. Based on these observations, other researchers have hypothesized that increased and decreased phytoplankton abundances during the 1960s as recorded at the Chicago water filtration plant were due to top-down effects rather than to phosphorus loading. This argument is reevaluated using two approaches. First, from the relationship between interannual variability in alewife and zooplankton species abundance during the summers of 1954, 1966, 1968, 1977, 1982, and 1984–87, I conclude that the effects of alewife predation on zooplankton community structure during the 1960s are less clear then originally proposed. Second, from estimates of Daphnia spp. grazing rates, considerations of the source of the long-term phytoplankton data used to support the top-down argument, regional differences in phytoplankton, zooplankton and alewife abundance trends, and historic water clarity observations, I conclude that existing data are insufficient to support the top-down argument that long-term trends in phytoplankton abundance were primarily affected by fluctuations in alewife abundance.

Long-Term Changes in the Macrobenthos of Southern Lake Michigan

1987 ◽  
Vol 44 (3) ◽  
pp. 515-524 ◽  
Author(s):  
Thomas F. Nalepa
Keyword(s):  
Lake Michigan ◽  
Fish Populations ◽  
Forage Fish ◽  
Future Trends ◽  
Sampling Depth ◽  
Benthic Survey ◽  
Comprehensive Survey ◽  
Long Term Trends

A benthic survey of 40 stations in southern Lake Michigan in 1980–81 was compared with results of studies conducted in the mid-1960's to evaluate long-term trends in populations. The three major benthic groups, Pontoporeia, oligochaetes, and sphaeriids, were significantly more abundant in 1980–81. Compared with the most comprehensive survey (conducted in 1964–67), Pontoporeia increased two- to fivefold at depths less than 50 m, but did not increase at depths greater than 50 m. Oligochaetes increased two- to threefold regardless of sampling depth, while sphaeriids increased twofold at depths less than 50 m but decreased somewhat at depths greater than 50 m. Although oligochaete abundances increased, overall shifts in species composition were not apparent. Changes in abundances of Pontoporeia may have been related to shifts in predation pressure from forage fish populations, but increased oligochaete abundances can likely be related to increased enrichment between the two sampling periods. Although apparent improvements in the water quality of Lake Michigan since the mid-1970's were not yet reflected by benthic populations in 1980–81, continued monitoring of the benthos should provide a useful indicator of future trends.

MONITORING POPULATION LEVELS OF EIGHT SPECIES OF NOCTUIDS WITH SEX-ATTRACTANT TRAPS IN SOUTHERN ALBERTA, 1978–1983: CONGRUENCY OF YEAR-TO-YEAR FLUCTUATIONS IN INTRASPECIFIC DENSITY SHOWN BY SUBSETS OF MONITORING SITES

1988 ◽  
Vol 120 (12) ◽  
pp. 1071-1078 ◽  
Author(s):  
J.R. Byers ◽  
D.L. Struble ◽  
G.B. Schaalje
Keyword(s):  
Sex Attractant ◽  
Population Estimates ◽  
Pest Species ◽  
Population Changes ◽  
Relative Population ◽  
Southern Alberta ◽  
Resource Requirements ◽  
Long Term Trends

AbstractThe abundance levels of eight species of cutworms and army worms were monitored with sex-attractant traps at 81 locations in a 13 000-km2 area of southern Alberta from 1978 to 1983. Year-to-year change in population levels could be consistently detected by monitoring at a relatively small number of locations. For all species, subsets of selected locations along transects, or random subsets of as few as five locations, showed year-to-year fluctuations in mean catch per trap that were similar in pattern to those of the whole monitored area. The results indicate that long-term surveillance monitoring of pest species of cutworms and armyworms to detect year-to-year population changes, and long-term trends, is feasible in terms of both the resource requirements and reliability of the relative population estimates.

Long-term trends in wildlife community structure and functional diversity in a village hunting zone in southeast Cameroon

2019 ◽  
Vol 29 (2) ◽  
pp. 571-590 ◽  
Author(s):  
Nikki Tagg ◽  
Jacques Keumo Kuenbou ◽  
Daan Willem Laméris ◽  
Fany Michelle Kamkeng Meigang ◽  
Sévilor Kekeunou ◽  
...  
Keyword(s):  
Community Structure ◽  
Functional Diversity ◽  
Long Term Trends

Long-term trends in the abundance and community structure of coastal zooplankton in the southern Benguela system, 1951–1996

1998 ◽  
Vol 19 (1) ◽  
pp. 317-332 ◽  
Author(s):  
H. M. Verheye ◽  
A. J. Richardson ◽  
L. Hutchings ◽  
G. Marska ◽  
D. Gianakouras
Keyword(s):  
Community Structure ◽  
Long Term Trends

Long-term trends of Lake Michigan benthos with emphasis on the southern basin

2020 ◽  
Vol 46 (3) ◽  
pp. 528-537 ◽  
Author(s):  
Knut Mehler ◽  
Lyubov E. Burlakova ◽  
Alexander Y. Karatayev ◽  
Ashley K. Elgin ◽  
Thomas F. Nalepa ◽  
...  
Keyword(s):  
Lake Michigan ◽  
Southern Basin ◽  
Long Term Trends

Long-term trends in fish community composition across coastal bays and lakes in the Lavaca–Colorado Estuary

2016 ◽  
Vol 94 (12) ◽  
pp. 871-884 ◽  
Author(s):  
Philip Matich ◽  
William B. Godwin ◽  
Mark Fisher
Keyword(s):  
Community Structure ◽  
Community Composition ◽  
Temporal Variability ◽  
Human Impacts ◽  
Fish Communities ◽  
Spatial And Temporal Variability ◽  
Important Species ◽  
Coastal Bays ◽  
Long Term Trends

Human impacts continue to alter community structure, emphasizing the need to understand how spatial and temporal variability in disturbance and conservation affect ecological communities to optimize management strategies. Here, we quantify fish species richness, diversity, and community structure across five coastal bays and lakes in the Lavaca–Colorado Estuary, Texas, over 30 years to investigate spatial and temporal variability in species assemblages, and the potential effects of resource management. Results suggest that fish communities varied both spatially and temporally from 1976 to 2008, with greater temporal shifts in habitats more proximate to the Gulf of Mexico and removed from human residential areas — diversity increased in Powderhorn Lake and spotted seatrout (Cynoscion nebulosus (Cuvier, 1830)) and red drum (Sciaenops ocellatus (L., 1766)) abundances increased in Oyster Lake following changes in fishing regulations. Natural fluctuations in environmental conditions coupled with limited access to lakes by geographic restraints may have led to more pronounced changes in community structure. However, the effects of fishing management on fish communities within small lakes and bays within the Lavaca–Colorado Estuary is likely habitat- and context-specific, and continued monitoring, especially among ecologically and economically important species, will provide insight into how environmental change and anthropogenic disturbance may affect long-term trends in coastal community composition.

Lipid Concentrations in Lake Michigan Fishes: Seasonal, Spatial, Ontogenetic, and Long-Term Trends

2000 ◽  
Vol 26 (4) ◽  
pp. 427-444 ◽  
Author(s):  
Charles P. Madenjian ◽  
Robert F. Elliott ◽  
Timothy J. DeSorcie ◽  
Ralph M. Stedman ◽  
Daniel V. O’Connor ◽  
...  
Keyword(s):  
Lake Michigan ◽  
Long Term Trends

Trend Reversal in Lake Michigan Contribution to Snowfall

2012 ◽  
Vol 51 (11) ◽  
pp. 2038-2046 ◽  
Author(s):  
Luke Bard ◽  
David A. R. Kristovich
Keyword(s):  
Great Lakes ◽  
Traffic Accident ◽  
Lake Michigan ◽  
Negative Consequences ◽  
Lake Effect ◽  
Long Term Trends ◽  
Autumn And Winter ◽  
Climate Studies ◽  
Trend Reversal

AbstractOne of the most notable ways the Laurentian Great Lakes impact the region’s climate is by augmenting snowfall in downwind locations during autumn and winter months. Among many negative consequences, this surplus of snow can cause substantial property damage to homes and can escalate the number of traffic accident–related injuries and fatalities. The consensus among several previous studies is that lake-effect snowfall increased during the twentieth century in various locations in the Great Lakes region. The goal of this study is to better understand variability and long-term trends in Lake Michigan’s lake-contribution snowfall (LCS). LCS accounts for both lake-effect and lake-enhanced events. In addition, this study updates findings from previous investigations using snowfall observations found by a recent study to be appropriate for climate studies. It is demonstrated that considerable variability exists in 5-yr periods of LCS east and south of Lake Michigan from 1920 to 2005. A general increase in LCS from the early 1920s to the 1950–80 period at locations typically downwind of the lake was found. Thereafter, LCS decreased through the early 2000s, indicating a distinct trend reversal that is not reported by earlier studies. The reasons for this reversal are unclear. The reversal is consistent with observed increasing minimum temperatures during winter months after the 1970s, however.

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