scholarly journals Analysing the Role of Environmental Stresses on Species Richness and the Process of Hierarchical Structuring of Species Abundances in Marine Gastropods communities at Suva (Fiji Islands)

2018 ◽  
pp. 200-233
Author(s):  
Jean Béguinot
Keyword(s):  
Species Richness ◽  
Species Diversity ◽  
Environmental Stresses ◽  
Chemical Pollution ◽  
Strong Increase ◽  
Feeding Guilds ◽  
Marine Gastropod ◽  
Species Abundances ◽  
Hierarchical Structuring ◽  
Mathematical Consequence

Anthropogenic environmental stresses, especially physio-chemical pollution, are causing steadily increasing threat to many ecosystems, among which coastal marine communities in tropical shallow waters are especially sensitive. In particular, species-rich marine gastropod assemblages are doomed to bear sharp drops in species diversity when exposed to pollutants released offshore. Yet, the details of the process of decline in species diversity remain to be addressed and analysed more deeply. By addressing a series of previously reported inventories of marine gastropod communities along a sharp gradient of pollution along southern coast at Suva (Fiji Archipelago), I first confirm the already recognised trend towards both a severe decrease in species richness and a strong increase of the unevenness in species abundance distribution, as a response to incremental pollution. Yet, the last trend – increased unevenness – reveals being essentially the purely mathematical consequence of the concomitant decline in species richness. In fact, the genuine intensity of the process of hierarchical structuring of species abundances proves remaining virtually unaffected by environmental degradation, contrary to what has been generally thought so far. Also, another unexpected aspect of the decline in species richness with growing pollution is that this decline is far from being primarily restricted to the set of rarest species; in fact, the originally abundant species are also largely implied in this decline. Moreover, considering separately the two co-occurring feeding guilds, it is shown that herbivores and carnivores are substantially involved the same in the drop in species diversity; as a result, their relative contributions in the community do not seem markedly contrasted by growing pollution. In another respect, a recently proposed paradigmatic hypothesis is supported, according to which the herbivore-guild has quite less numerous species with more unevenly distributed abundances, as compared to the carnivore-guild. Yet, once again, this increased unevenness is essentially the purely mathematical consequence of the concomitant decline in species richness; the genuine intensity of the process of hierarchical structuring of species abundances does remain substantially unchanged. At last, a comparatively extremely high sensitivity to pollution is highlighted for the emblematic genus Conus, which suffers, here, a dramatic drop in species diversity.

scholarly journals Carbon Sequestration in Relation to Topographic Aspects and Land Use in Northeast of Thailand

2018 ◽  
pp. 118-137 ◽  
Author(s):  
Kazi Kaimul Islam ◽  
Somchai Anusontpornperm ◽  
Irb Kheoruenromne ◽  
Suphicha Thanachit
Keyword(s):  
Species Richness ◽  
Climatic Change ◽  
Hot Spot ◽  
Local Level ◽  
Dominant Factor ◽  
Essential Information ◽  
Total Species Richness ◽  
Western Ghats Of India ◽  
Species Abundances ◽  
Hierarchical Structuring

The Distribution of Species Abundances within natural communities – when properly analysed – can provide essential information regarding general aspects of the internal organisation of these communities. In particular, true species richness on the one hand and the intensity of the process of hierarchical structuring of species abundances on the other hand may be estimated independently and, thereby, can provide truly complementary information. In turn, specific issues may thereby be addressed. For example, whether one unique dominant factor or numerous combined factors are involved in the structuring process of a community can be tested contradictorily. Although these methods are not new conceptually, their implementation in common practice remains scarce. The reason is that the relevant implementation of these methods requires to be sure that virtually all member-species in the community have been sampled. As exhaustive samplings often reveal difficult to achieve in practice, an appropriate, least-biased procedure of numerical extrapolation of incomplete inventories is imperatively required. Considering the steadily increasing threats to the environment and biodiversity, especially facing the on-going climatic change, time has come now with ever greater urgency to go beyond the apparent limits of non-exhaustive sampling and make the most of what is available in terms of recorded field data, whatever the degree of incompleteness of species inventories. As a modest and limited attempt to concretise this wish at the local level, I try, hereafter, to highlight the importance of additional information that may be unveiled  through adequate post-analysis of a set of eight frog communities, recently inventoried by Katwate, Apte & Raut in an amphibian hot-spot in the north-western Ghats of India. At last, the likely variations of both total species richness and the intensity of hierarchical structuring of species abundance are simulated as an answer to the steadily increasing influence of the ongoing climatic change.

scholarly journals Analyzing the Role of Increasing Water Pollution on Species-Richness, Interspecific-Competition and Abundance-Unevenness in Reef-Associated Fish Communities, off Jakarta Bay (Indonesia)

2021 ◽  
pp. 18-43
Author(s):  
Jean Béguinot
Keyword(s):  
Species Richness ◽  
Interspecific Competition ◽  
Fish Assemblages ◽  
Fish Communities ◽  
Empirical Support ◽  
Feeding Guilds ◽  
Common Trend ◽  
Total Species Richness ◽  
Species Abundances ◽  
The One

Not far from the exceptionally rich ‘Coral Triangle’ on the one hand but, on the other hand, exposed to strongly varying degree of anthropogenic environmental stresses, the reef-associated fish assemblages all along ‘Seribu Islands’ (off Jakarta Bay) are, thus, confronted to both positive and negative ecological influences. As such, these fish assemblages offer especially interesting opportunities to analyze these opposite ecological influences, at both the descriptive and the functional points of views. The least-biased numerical extrapolation of a series of recently reported – yet incomplete – samplings has allowed a sub-exhaustive account of both the estimated total species-richness and the completed distribution of species abundances – including the set of those rarer species which had remained unrecorded. Thanks to this numerically completed information, it became possible to tackle some important issues – which otherwise would have remained difficult to address properly. First, a remarkably good correlation was highlighted between the distance of fish assemblages to Jakarta Bay (distance considered as a reliable surrogate to the improvement of environmental conditions for fish assemblages) and a theoretically derived index characterizing the accommodation capacity of sites for fish assemblages. This good correlation suggests that this index offer a way to reliably accounts for the “environmental quality” of marine waters, as appreciated by fish communities. In quite another respect, comparing primary and secondary-feeding guilds, provides still further empirical support to a seemingly common trend according to which the guild of secondary-feeders features usually more species-rich, while exhibiting less interspecific competition intensity at niche overlaps, than does the primary-feeders guild.

scholarly journals Estimating True Species Richness and the Degree of Hierarchical Structuring of Species Abundances in Eight Frog Communities from the North-Western Ghats of India

2018 ◽  
pp. 118-137
Author(s):  
Jean Béguinot
Keyword(s):  
Species Richness ◽  
Climatic Change ◽  
Western Ghats ◽  
Dominant Factor ◽  
Essential Information ◽  
The North ◽  
Western Ghats Of India ◽  
Species Abundances ◽  
Hierarchical Structuring ◽  
North Western

The Distribution of Species Abundances within natural communities – when properly analysed – can provide essential information regarding general aspects of the internal organisation of these communities. In particular, true species richness on the one hand and the intensity of the process of hierarchical structuring of species abundances on the other hand may be estimated independently and, thereby, can provide truly complementary information. In turn, specific issues may thereby be addressed. For example, whether one unique dominant factor or numerous combined factors are involved in the structuring process of a community can be tested contradictorily. Although these methods are not new conceptually, their implementation in common practice remains scarce. The reason is that the relevant implementation of these methods requires to be sure that virtually all member-species in the community have been sampled. As exhaustive samplings often reveal difficult to achieve in practice, an appropriate, least-biased procedure of numerical extrapolation of incomplete inventories is imperatively required. Considering the steadily increasing threats to the environment and biodiversity, especially facing the on-going climatic change, time has come now with ever greater urgency to go beyond the apparent limits of non-exhaustive sampling and make the most of what is available in terms of recorded field data, whatever the degree of incompleteness of species inventories. As a modest and limited attempt to concretise this wish at the local level, I try, hereafter, to highlight the importance of additional information that may be unveiled  through adequate post-analysis of a set of eight frog communities, recently inventoried by Katwate, Apte & Raut in an amphibian hot-spot in the north-western Ghats of India. At last, the likely variations of both total species richness and the intensity of hierarchical structuring of species abundance are simulated as an answer to the steadily increasing influence of the ongoing climatic change.

scholarly journals Influence of Coral Architecture on Species Richness and the Hierarchical Structuration of Species Abundances in Reef Fish Communities: A Case Study in the Eastern Tropical Pacific

2019 ◽  
pp. 1-21
Author(s):  
Jean Béguinot
Keyword(s):  
Species Richness ◽  
Fish Community ◽  
Fish Communities ◽  
Total Species Richness ◽  
Species Abundances ◽  
Hierarchical Structuring ◽  
Complex Architecture ◽  
Total Species

The role of coral reef architecture on species richness and the internal structuration of the associated fish communities has already been addressed several times. The reported results, however, usually remain controversial, possibly because they are based upon incomplete field data issued from partial inventories. Indeed, incomplete samplings are almost unavoidable in practice with such species-rich communities having very uneven distribution of abundances. In this context, the numerical extrapolation of incompletely sampled communities may serve as a reliable surrogate. Accordingly, numerical extrapolations were implemented, here, to compare two fish-communities respectively associated to coral reefs that sharply differ from each-other by their topographic architectures. Both a higher total species richness and a sharper unevenness of species abundances were found to characterize the fish community associated to the more tormented reef habitat exhibiting the more complex architecture. Yet, paradoxically, the true intensity of the underlying process of hierarchical structuring of abundances proves being insensitive to the architecture of coral habitats. This apparent opposition between the unevenness pattern and the underlying structuring process results, in fact, from the additional negative dependence of abundance unevenness upon species richness.

scholarly journals Influence of Fishing Activity on Total Species Richness and Abundance Unevenness in Reef Fish Communities: A Case Study in a Brazilian Tropical Coral Complex

2019 ◽  
pp. 58-76
Author(s):  
Jean Béguinot
Keyword(s):  
Species Richness ◽  
Reef Fish ◽  
Fish Communities ◽  
Fishing Activity ◽  
Total Species Richness ◽  
Tropical Coral ◽  
Species Abundances ◽  
Hierarchical Structuring ◽  
Species Richness And Abundance ◽  
Total Species

The internal organization of reef-fish communities, particularly the species richness and the hierarchical structuring of species abundances, depends on many environmental factors, including fishing intensity and proportion of macroalgal cover which are expected to have determinant influences. However, reported studies on this topic are generally based on incomplete samplings (almost unavoidable in practice when dealing with highly uneven and species-rich communities), so that the derived results can be appreciably skewed. To overcome this difficulty, the incomplete samplings involved in this study were completed numerically through a reliable extrapolation procedure. This precaution provided a safe confirmation that reduced fishing activity and increased macroalgae cover both contribute to enhance the total species richness and to reduce the abundance unevenness in these reef fish communities.  Yet, it is shown that this reduction of abundance unevenness is almost entirely attributable to the increase in species richness.

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.

scholarly journals Old and new challenges in using species diversity for assessing biodiversity

2011 ◽  
Vol 366 (1576) ◽  
pp. 2426-2437 ◽  
Author(s):  
Alessandro Chiarucci ◽  
Giovanni Bacaro ◽  
Samuel M. Scheiner
Keyword(s):  
Species Diversity ◽  
Quantitative Measurement ◽  
Phylogenetic Distance ◽  
Existing Problems ◽  
Species Abundances ◽  
Species Lists ◽  
Assessment And Monitoring ◽  
New Challenges ◽  
Patterns And Processes ◽  
Conservation And Management

Although the maintenance of diversity of living systems is critical for ecosystem functioning, the accelerating pace of global change is threatening its preservation. Standardized methods for biodiversity assessment and monitoring are needed. Species diversity is one of the most widely adopted metrics for assessing patterns and processes of biodiversity, at both ecological and biogeographic scales. However, those perspectives differ because of the types of data that can be feasibly collected, resulting in differences in the questions that can be addressed. Despite a theoretical consensus on diversity metrics, standardized methods for its measurement are lacking, especially at the scales needed to monitor biodiversity for conservation and management purposes. We review the conceptual framework for species diversity, examine common metrics, and explore their use for biodiversity conservation and management. Key differences in diversity measures at ecological and biogeographic scales are the completeness of species lists and the ability to include information on species abundances. We analyse the major pitfalls and problems with quantitative measurement of species diversity, look at the use of weighting measures by phylogenetic distance, discuss potential solutions and propose a research agenda to solve the major existing problems.

scholarly journals What Does Productivity Really Mean? Towards an Integrative Paradigm in the Search for Biodiversity-Productivity Relationships

2013 ◽  
Vol 41 (1) ◽  
pp. 36 ◽  
Author(s):  
Liangjun HU ◽  
Qinfeng GUO
Keyword(s):  
Species Richness ◽  
Species Diversity ◽  
Biomass Production ◽  
Real Root ◽  
Spatial Scaling ◽  
Ecological Processes ◽  
The Real ◽  
Community Or ◽  
Per Se ◽  
Underlying Mechanisms

How species diversity relates to productivity remains a major debate. To date, however, the underlying mechanisms that regulate the ecological processes involved are still poorly understood. Three major issues persist in early efforts at resolution. First, in the context that productivity drives species diversity, how the pathways operate is poorly-explained. Second, productivity  per se varies with community or ecosystem maturity. If diversity indeed drives productivity, the criterion of choosing appropriate measures for productivity is not available. Third, spatial scaling suggests that sampling based on small-plots may not be suitable for formulating species richness-productivity relationships (SRPRs). Thus, the long-standing assumption simply linking diversity with productivity and pursuing a generalizing pattern may not be robust. We argue that productivity, though defined as ‘the rate of biomass production’, has been measured in two ways environmental surrogates and biomass production leading to misinterpretations and difficulty in the pursuit of generalizable SRPRs. To tackle these issues, we developed an integrative theoretical paradigm encompassing richer biological and physical contexts and clearly reconciling the major processes of the systems, using proper productivity measures and sampling units. We conclude that loose interpretation and confounding measures of productivity may be the real root of current SRPR inconsistencies and debate.

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