scholarly journals Mortality, Population and Community Dynamics of the Glass Sponge Dominated Community “The Forest of the Weird” From the Ridge Seamount, Johnston Atoll, Pacific Ocean

2020 ◽  
Vol 7 ◽  
Author(s):  
Emily G. Mitchell ◽  
Simon Harris
Keyword(s):  
Pacific Ocean ◽  
Community Dynamics ◽  
Glass Sponge ◽  
Population And Community Dynamics

The ecology of parasites of freshwater fishes: the search for patterns

Parasitology ◽  
2009 ◽  
Vol 136 (12) ◽  
pp. 1653-1662 ◽  
Author(s):  
C. R. KENNEDY
Keyword(s):  
Community Dynamics ◽  
Parasite Community ◽  
Freshwater Fishes ◽  
Convincing Evidence ◽  
Helminth Parasites ◽  
Parasite Communities ◽  
Space And Time ◽  
Long Time ◽  
Population And Community Dynamics ◽  
Parasite Populations

SUMMARYDevelopments in the study of the ecology of helminth parasites of freshwater fishes over the last half century are reviewed. Most research has of necessity been field based and has involved the search for patterns in population and community dynamics that are repeatable in space and time. Mathematical models predict that under certain conditions host and parasite populations can attain equilibrial levels through operation of regulatory factors. Such factors have been identified in several host-parasite systems and some parasite populations have been shown to persist over long time-periods. However, there is no convincing evidence that fish parasite populations are stable and regulated since in all cases alternative explanations are equally acceptable and it appears that they are non-equilibrial systems. It has proved particularly difficult to detect replicable patterns in parasite communities. Inter-specific competition, evidenced by functional and numerical responses, has been detected in several communities but its occurrence is erratic and its significance unclear. Some studies have failed to find any nested patterns in parasite community structure and richness, whereas others have identified such patterns although they are seldom constant over space and time. Departures from randomness appear to be the exception and then only temporary. It appears that parasite communities are non-equilibrial, stochastic assemblages rather than structured and organized.

scholarly journals Spatial distribution and survival rate of waterfrog tadpoles in relation to biotic and abiotic factors: a field experiment

2001 ◽  
Vol 22 (1) ◽  
pp. 21-32 ◽  
Author(s):  
Sylvie Thurnheer ◽  
Heinz-Ulrich Reyer
Keyword(s):  
Spatial Distribution ◽  
Community Dynamics ◽  
Abiotic Factors ◽  
Rana Esculenta ◽  
Natural Conditions ◽  
Major Purpose ◽  
Biotic And Abiotic Factors ◽  
Lab Experiments ◽  
Shallow Zone ◽  
Population And Community Dynamics

AbstractPredictions about population and community dynamics are usually based on lab experiments. Because the results are difficult to transfer to natural conditions, the major purpose of this study was to test the effects of biotic and abiotic factors on tadpole populations in a natural environment. We stocked six ponds, created the previous year, with known numbers of Rana esculenta and R. lessonae tadpoles and followed their development over several months. When compared among ponds, tadpole density correlated positively with the nitrate:phosphate ratio. This suggests that water chemistry may have affected survival, either directly or indirectly via productivity. Within ponds, both species showed a clear preference for the shallow zone. This behavior probably reflects a preference for warm water close to the surface, rather than avoidance of predators, because relative densities of odonates also increased from deep to shallow zones. This study is one of few that not only considers the distribution of the anuran tadpoles but the distribution of their predators as well.

scholarly journals Lake sedimentary DNA to reveal long-term changes in aquatic biodiversity and ecosystem functioning

2021 ◽  
Vol 4 ◽  
Author(s):  
Isabelle Domaizon
Keyword(s):  
Community Dynamics ◽  
Temporal Dynamics ◽  
Critical Research ◽  
Aquatic Biodiversity ◽  
Biological Variables ◽  
Long Term Changes ◽  
Research Questions ◽  
Population And Community Dynamics ◽  
Emerging Topics

The emergence of molecular analyses based on the sequencing of sedimentary DNA has opened up many new areas of inquiry in paleolimnology. DNA preserved in sediments (SedDNA) offers the possibility to consider taxa that were traditionally not accessible because they do not leave distinct morphological fossils. Recent applications that considered a diversity of biological groups (including bacteria, protists, zooplankton, fish) illustrate how efficiently SedDNA-based methods complement both classical paleolimnology proxies and limnological data. The knowledge gained from this approach is very diverse in scope, ranging from quantifying natural variability in population and community dynamics to understanding how these biological variables respond to anthropogenic disturbances and climatic change. The use of lake sedimentary DNA to track long-term changes in aquatic biota is a rapidly advancing field of research. Based on recent applications, this presentation illustrates (i) the potential and challenges associated with the study of SedDNA to address critical research questions in lacustrine ecology (ii) the main methodological precautions to be taken into account for implementing these types of DNA analyses (i.e. best practices) and (iii) the emerging topics that could be addressed using sedimentary DNA, in particular to reconstruct the temporal dynamics of lacustrine biodiversity.

A new species of glass sponge (Hexactinellida: Sceptrulophora: Uncinateridae) from the Weijia Seamount in the northwestern Pacific Ocean

Zootaxa ◽  
2020 ◽  
Vol 4878 (2) ◽  
pp. 322-334
Author(s):  
CHENGCHENG SHEN ◽  
DONGSHENG ZHANG ◽  
BO LU ◽  
CHUNSHENG WANG
Keyword(s):  
New Species ◽  
Pacific Ocean ◽  
Northwestern Pacific ◽  
Northwestern Pacific Ocean ◽  
Glass Sponge ◽  
Body Form ◽  
Hexactinellid Sponge ◽  
The Family ◽  
Molecular Phylogenetic ◽  
A New Species

In this article we report on a hexactinellid sponge new to science, Tretopleura weijicus sp. nov., which was collected from the Weijia Seamount in the northwestern Pacific Ocean at a depth of 1995 m. Its blade-like and branching body form, the primary choanosomal framework consisting of multiaxial longitudinal strands without synapticula, and the presence of sceptrules suggest placement within the family Uncinateridae Reiswig, 2002, which is also supported by molecular phylogenetic evidence from COI and 16S sequences. The absence of swollen dermal spurs or regular pentactins and the presence of two types of discohexasters characterize it as a new species. More specimens should be collected to revise the generic characters.

scholarly journals Grazing resistance in phytoplankton

Hydrobiologia ◽  
2020 ◽  
Vol 848 (1) ◽  
pp. 237-249 ◽  
Author(s):  
Miquel Lürling
Keyword(s):  
Community Dynamics ◽  
Phytoplankton Community ◽  
Rapid Evolution ◽  
Variable Environment ◽  
Trade Off ◽  
Defense Strategies ◽  
Trade Offs ◽  
Grazing Resistance ◽  
Population And Community Dynamics

AbstractPhytoplankton is confronted with a variable assemblage of zooplankton grazers that create a strong selection pressure for traits that reduce mortality. Phytoplankton is, however, also challenged to remain suspended and to acquire sufficient resources for growth. Consequently, phytoplanktic organisms have evolved a variety of strategies to survive in a variable environment. An overview is presented of the various phytoplankton defense strategies, and costs and benefits of phytoplankton defenses with a zooming in on grazer-induced colony formation. The trade-off between phytoplankton competitive abilities and defenses against grazing favor adaptive trait changes—rapid evolution and phenotypic plasticity—that have the potential to influence population and community dynamics, as exemplified by controlled chemostat experiments. An interspecific defense–growth trade-off could explain seasonal shifts in the species composition of an in situ phytoplankton community yielding defense and growth rate as key traits of the phytoplankton. The importance of grazing and protection against grazing in shaping the phytoplankton community structure should not be underestimated. The trade-offs between nutrient acquisition, remaining suspended, and grazing resistance generate the dynamic phytoplankton community composition.

scholarly journals Employing plant functional groups to advance seed dispersal ecology and conservation

AoB Plants ◽  
2019 ◽  
Vol 11 (2) ◽  
Author(s):  
Clare Aslan ◽  
Noelle G Beckman ◽  
Haldre S Rogers ◽  
Judie Bronstein ◽  
Damaris Zurell ◽  
...  
Keyword(s):  
Seed Dispersal ◽  
Functional Groups ◽  
Community Dynamics ◽  
Single Species ◽  
Plant Functional Groups ◽  
Similar Species ◽  
Seed Dispersal Effectiveness ◽  
Data Collection And Analysis ◽  
Population And Community Dynamics ◽  
Species Specific

Abstract Seed dispersal enables plants to reach hospitable germination sites and escape natural enemies. Understanding when and how much seed dispersal matters to plant fitness is critical for understanding plant population and community dynamics. At the same time, the complexity of factors that determine if a seed will be successfully dispersed and subsequently develop into a reproductive plant is daunting. Quantifying all factors that may influence seed dispersal effectiveness for any potential seed-vector relationship would require an unrealistically large amount of time, materials and financial resources. On the other hand, being able to make dispersal predictions is critical for predicting whether single species and entire ecosystems will be resilient to global change. Building on current frameworks, we here posit that seed dispersal ecology should adopt plant functional groups as analytical units to reduce this complexity to manageable levels. Functional groups can be used to distinguish, for their constituent species, whether it matters (i) if seeds are dispersed, (ii) into what context they are dispersed and (iii) what vectors disperse them. To avoid overgeneralization, we propose that the utility of these functional groups may be assessed by generating predictions based on the groups and then testing those predictions against species-specific data. We suggest that data collection and analysis can then be guided by robust functional group definitions. Generalizing across similar species in this way could help us to better understand the population and community dynamics of plants and tackle the complexity of seed dispersal as well as its disruption.

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