The decline of Daphnia hyalina galeata in Lago Maggiore: a comparison of the population dynamics before and after oligotrophication

2000 ◽  
Vol 62 (2) ◽  
pp. 142-153 ◽  
Author(s):  
Marina Manca ◽  
Claudio Ramoni ◽  
Patrizia Comoli
Keyword(s):  
Population Dynamics ◽  
Before And After ◽  
Daphnia Hyalina

scholarly journals Population dynamics of a commercially harvested, non-native bivalve in an area protected for shorebirds: Ruditapes philippinarum in Poole Harbour, UK

2019 ◽  
Vol 32 ◽  
pp. 10 ◽  
Author(s):  
Leo John Clarke ◽  
Luciana S. Esteves ◽  
Richard A. Stillman ◽  
Roger J.H. Herbert
Keyword(s):  
Population Dynamics ◽  
Marine Protected Area ◽  
Condition Index ◽  
Ruditapes Philippinarum ◽  
Ecological Interactions ◽  
Fishing Season ◽  
Before And After ◽  
Harvesting Efficiency ◽  
The Uk ◽  
Lower Biomass

The Manila clam Ruditapes philippinarum is one of the most commercially valuable bivalve species worldwide and its range is expanding, facilitated by aquaculture and fishing activities. In existing and new systems, the species may become commercially and ecologically important, supporting both local fishing activities and populations of shorebird predators of conservation importance. This study assessed potential fishing effects and population dynamics of R. philippinarum in Poole Harbour, a marine protected area on the south coast of the UK, where the species is important for oystercatcher Haematopus ostralegus as well as local fishers. Sampling was undertaken across three sites of different fishing intensities before and after the 2015 fishing season, which extends into the key overwintering period for shorebird populations. Significant differences in density, size and condition index are evident between sites, with the heavily dredged site supporting clams of poorer condition. Across the dredge season, clam densities in the heavily fished area were significantly reduced, with a harvesting efficiency of legally harvestable clams of up to 95% in this area. Despite occurring at significantly higher densities and growing faster under heavy fishing pressure, lower biomass and condition index of R. philippinarum in this area, coupled with the dramatic reduction in densities across the fishing season, may be of concern to managers who must consider the wider ecological interactions of harvesting with the interest of nature conservation and site integrity.

Population dynamics and production of Daphnia hyalina var. lacustris in Farmoor I, a shallow eutrophic reservoir

1979 ◽  
Vol 1 (1) ◽  
pp. 45-65 ◽  
Author(s):  
Helen R. Jones ◽  
T. J. Lack ◽  
C. S. Jones
Keyword(s):  
Population Dynamics ◽  
Eutrophic Reservoir ◽  
Daphnia Hyalina

scholarly journals Antagonism and population dynamics of Acinetobacter baumannii from US military treatment centers

2017 ◽  
Author(s):  
Rae A Heitkamp ◽  
Amy M Zale ◽  
Benjamin C Kirkup
Keyword(s):  
Population Dynamics ◽  
Acinetobacter Baumannii ◽  
Bacterial Species ◽  
Hospital Setting ◽  
Antagonistic Activity ◽  
Resistant Bacteria ◽  
Natural Environments ◽  
Bacterial Populations ◽  
Starting Point ◽  
Before And After

Antibiotic-resistant bacteria complicate many infections and can be difficult to eradicate from hospitals. The population dynamics and ecology of these organisms in the hospital setting, however, is not well understood. Here, we report extensive strain-based antagonistic interactions occurring in military clinical isolates of Acinetobacter baumannii, a bacterial species that causes many drug-resistant hospital-associated infections. Sequence-based phylogenetic analysis of isolates allowed for differentiation to two major clades, with one of the clades representing two closely related genetic groups. Antagonistic activity was detected using a spot-plate assay to test pairwise interactions of all isolates. Isolates exhibited extensive and diverse patterns of antagonism against other isolates. One major clade of isolates had a distinct change in antagonism phenotype between isolates that differed by one base pair out of ~1500bp sequenced, with consistent antagonism of one group of isolates by the other. Both the antagonistic and the sensitive group exhibited extensive drug resistance. The first isolate of the antagonistic group was cultured in May 2010. The proportion of isolates from the antagonistic group collected before and after July 2010 increased from 2% to 76%. The results of this early study of the ecology of hospital-associated bacterial populations are discussed in the context of the species ecology of bacteria in natural environments. This work is a potential starting point for investigations into ecological interventions for infection control in hospitals.

scholarly journals Weed population dynamics in rice crops resulting from post-emergent herbicide applications

2017 ◽  
Vol 70 (1) ◽  
pp. 8035-8043
Author(s):  
Javier Ramírez ◽  
Verónica Hoyos ◽  
Guido Plaza
Keyword(s):  
Population Dynamics ◽  
Community Structure ◽  
Relative Frequency ◽  
Importance Value Index ◽  
Importance Value ◽  
Weed Population ◽  
Weed Communities ◽  
Weed Population Dynamics ◽  
Importance Index ◽  
Before And After

Studies on weed population dynamics are based on observing and recording changes in weed communities in response to effects of disturbances in crop management. The present study aimed to evaluate weed population dynamics in rice crops in Tolima, Colombia, resulting from post-emergent herbicide applications. Sampling was carried out in 0.1% of the cultivated area, marking out a 1 ha area in each commercial lot. Samples were taken before and after post-emergent applications. Evaluated variables were frequency, density, and cover. The data were analyzed using the Importance Value Index (IVI). Results demonstrated that Echinochloa colona was the most important weed of all of the evaluated zones, before and after post-emergent herbicide applications. Other notable species included Digitaria ciliaris, Cyperus iria and Ischaemum rugosum. Relative frequency variable was the most influential on the importance index of the species. Furthermore, herbicide applications generated changes in the community structure in the evaluated zones and in each evaluation.

Population dynamics of tree seedlings in a mixed dipterocarp rainforest before and after logging and crown liberation

1996 ◽  
Vol 81 (1-3) ◽  
pp. 85-94 ◽  
Author(s):  
Jussi Kuusipalo ◽  
Yusuf Jafarsidik ◽  
Göran Ådjers ◽  
Kari Tuomela
Keyword(s):  
Population Dynamics ◽  
Tree Seedlings ◽  
Before And After

Population dynamics and production of Daphnia hyalina in a eutrophic reservoir

1974 ◽  
Vol 4 (5) ◽  
pp. 445-465 ◽  
Author(s):  
D. G. GEORGE ◽  
R. W. EDWARDS
Keyword(s):  
Population Dynamics ◽  
Eutrophic Reservoir ◽  
Daphnia Hyalina

Diel vertical migration of Daphnia hyalina (sensu latiori) in Lake Maarsseveen: Part 2. Aspects of population dynamics

1991 ◽  
Vol 122 (4) ◽  
pp. 385-401
Author(s):  
J. Ringelberg ◽  
B. J. G. Flik ◽  
D. Lindenaar ◽  
K. Royackers
Keyword(s):  
Population Dynamics ◽  
Vertical Migration ◽  
Diel Vertical Migration ◽  
Daphnia Hyalina

scholarly journals Stock collapse and its effect on species interactions: cod and herring in the Norwegian-Barents Seas system as an example

2021 ◽  
Author(s):  
Joel Durant ◽  
Leana Aarvold ◽  
Øystein Langangen
Keyword(s):  
Population Dynamics ◽  
Species Interactions ◽  
Gadus Morhua ◽  
Barents Sea ◽  
Biotic Interactions ◽  
Clupea Harengus ◽  
Late 20Th Century ◽  
Before And After ◽  
The Difference ◽  
Stock Collapse

Both the Norwegian Spring Spawning herring (Clupea harengus) and the Northeast Arctic cod (Gadus morhua) are examples of how the overexploitation of marine fish populations was leading to a strong reduction even so stock collapse, with a strong decline in the associated fisheries, followed by a recovery. Cod and herring are both part of the Barents Sea ecosystem, which experienced major warming events in the early (1920-1940) and late 20th century. While the collapse or near collapse of these stocks seems to be linked to instability created by overfishing and climate, the difference of population dynamics before and after is not fully understood. In particular, it is unclear how the changes in population dynamics before and after the collapses are associated with biotic interactions. The combination of the availability of unique long-term time series for herring and cod makes it a well-suited study system to investigate the effects of collapse. We examine how species interactions may differently affect the herring and cod population dynamic before and after a collapse. Particularly we explore, using a GAM modelling approach, how herring could affect cod and reciprocally. We found that the effect on herring of cod biomass that was generally positive (i.e., covariation) became negative after the collapse (i.e., predation or competition). Likewise a change occurred for the cod, the juvenile herring biomass that had no effect before the collapse had a negative one after. Our results indicate that population collapses may lead to altered inter-specific interactions as well as altered response to abiotic environmental variations. While the stocks are at similar abundance levels before and after the collapses the system is potentially different in its functioning and may require different management action.

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