scholarly journals Habitat degradation of an eelgrass bed variably affects epifaunal biodiversity

2018 ◽  
Author(s):  
Francesca Rossi ◽  
Marie Pierrejean
Keyword(s):  
Species Diversity ◽  
Zostera Marina ◽  
Habitat Complexity ◽  
Photosynthetic Activity ◽  
Habitat Degradation ◽  
Shoot Density ◽  
Seagrass Habitat ◽  
Abiotic Stressors ◽  
Complex Patterns ◽  
Epifaunal Assemblages

Seagrass habitat complexity can determine species diversity and abundance, through, for instance, changes in the availability of microhabitats, refuge from predators or changes in the intensity and frequency of abiotic stressors. Human-related perturbations cause seagrass habitat degradation and, therefore, reduce its complexity, thereby affecting biodiversity. We have followed the epifaunal assemblages of a Zostera marina meadow and deliberately modified seagrass shoot density three times during a year to measure how epifaunal assemblages responded to habitat degradation and whether patterns of response were consistent through time. We have also measured in the laboratory how epifauna controlled epiphyte biomass, which could feedback on seagrass photosynthetic activity, growth and productivity, thereby changing its resilience to disturbances. Results have shown complex patterns, variable in time.

scholarly journals Habitat degradation of an eelgrass bed variably affects epifaunal biodiversity

2018 ◽  
Author(s):  
Francesca Rossi ◽  
Marie Pierrejean
Keyword(s):  
Species Diversity ◽  
Zostera Marina ◽  
Habitat Complexity ◽  
Photosynthetic Activity ◽  
Habitat Degradation ◽  
Shoot Density ◽  
Seagrass Habitat ◽  
Abiotic Stressors ◽  
Complex Patterns ◽  
Epifaunal Assemblages

Seagrass habitat complexity can determine species diversity and abundance, through, for instance, changes in the availability of microhabitats, refuge from predators or changes in the intensity and frequency of abiotic stressors. Human-related perturbations cause seagrass habitat degradation and, therefore, reduce its complexity, thereby affecting biodiversity. We have followed the epifaunal assemblages of a Zostera marina meadow and deliberately modified seagrass shoot density three times during a year to measure how epifaunal assemblages responded to habitat degradation and whether patterns of response were consistent through time. We have also measured in the laboratory how epifauna controlled epiphyte biomass, which could feedback on seagrass photosynthetic activity, growth and productivity, thereby changing its resilience to disturbances. Results have shown complex patterns, variable in time.

Seagrass characterization on the southern Pacific coast of Costa Rica: history, vegetation, and environment

2020 ◽  
Vol 63 (5) ◽  
pp. 429-438
Author(s):  
Jimena Samper-Villarreal ◽  
Jorge Cortés
Keyword(s):  
Costa Rica ◽  
Pacific Coast ◽  
Management Strategies ◽  
Shoot Density ◽  
Nutrient Concentrations ◽  
Seagrass Habitat ◽  
Spatial And Temporal Variability ◽  
Seagrass Species ◽  
Seagrass Biomass ◽  
Herbarium Collections

AbstractSeagrass conservation and management requires scientific understanding of spatial and temporal variability, information that is currently limited for the Eastern Tropical Pacific (ETP). Here, we analysed seagrass presence based on previous reports, herbarium collections and stakeholder knowledge, combined with field characterization in Golfo Dulce, southern Pacific coast of Costa Rica. Seagrasses were found at multiple locations along a narrow border close to shore and in up to 6 m depth within Golfo Dulce, dating back to 1969. Two seagrass species were found, Halophila baillonii and Halodule beaudettei. Seagrass biomass values for Golfo Dulce (12.0 ± 8.5 g DW m−2) were lower and water nutrient concentrations were higher than previously reported in the gulf. Shoot density (1513 ± 767 shoots m−2) was similar to previous reports. Stable isotope values in seagrass were −11.3 ± 1.0‰ δ13C and 1.2 ± 0.9‰ δ15N; while those in sediments were −26.1 ± 1.3 and 2.5 ± 0.9‰. In Golfo Dulce, isotopic values of both seagrass species do not overlap with other known primary producers. Management strategies should aim to minimize known seagrass stressors, protect potential seagrass habitat, and take into account the dynamic life strategies of the two seagrass species found.

Spatiotemporal dynamics of the molluscan community associated with seagrass on the western equatorial Atlantic

2019 ◽  
Vol 99 (06) ◽  
pp. 1285-1294 ◽  
Author(s):  
Lorraine Lopes Cavalcante ◽  
Cristiane Xerez Barroso ◽  
Pedro Bastos de Macêdo Carneiro ◽  
Helena Matthews-Cascon
Keyword(s):  
Seagrass Meadow ◽  
Shoot Density ◽  
Halodule Wrightii ◽  
Conservation Unit ◽  
Equatorial Atlantic ◽  
Eastern Brazil ◽  
Spatial Changes ◽  
North Eastern ◽  
Temporal And Spatial ◽  
Epifaunal Assemblages

AbstractThis study aimed to qualitatively and quantitatively analyse the molluscan assemblages associated with a Halodule wrightii seagrass bed in a rarely studied area within a conservation unit in north-eastern Brazil. Seasonal and spatial changes in several seagrass meadow characteristics, including sediment, were evaluated to explain temporal and spatial variations in the molluscs found there. The molluscan community differed in its structure among periods and meadows, as well as in the composition of its infaunal and epifaunal assemblages. The results of this study indicated that molluscs are affected by the particular characteristics of a seagrass meadow, especially by its location in the intertidal zone, more than by the area of the meadow. Molluscs were also affected by other characteristics of the seagrass meadow, such as above-ground biomass and shoot density. Changes in all molluscan assemblages were also mediated by differences among months and seasons in this region of the western equatorial Atlantic, but not by seasonal changes of the meadow. The studied meadow was found to be one of the densest in Brazil, which has considerable importance to its associated fauna.

scholarly journals Toxicity of reduced nitrogen in eelgrass (Zostera marina) is highly dependent on shoot density and pH

Oecologia ◽  
2008 ◽  
Vol 158 (3) ◽  
pp. 411-419 ◽  
Author(s):  
T. van der Heide ◽  
A. J. P. Smolders ◽  
B. G. A. Rijkens ◽  
E. H. van Nes ◽  
M. M. van Katwijk ◽  
...  
Keyword(s):  
Zostera Marina ◽  
Shoot Density ◽  
Reduced Nitrogen

scholarly journals Abundance and Distribution of Odonates (Dragonflies and Damselflies) In Akwa Ibom State, Nigeria

2018 ◽  
Vol 1 (1) ◽  
pp. 33-38
Author(s):  
Kehinde A. Kemabonta ◽  
Rosemary Essien ◽  
Babasola W. Adu ◽  
Sylvester U. Ogbogu ◽  
Abdussalam Iysa ◽  
...  
Keyword(s):  
Species Diversity ◽  
Statistical Difference ◽  
Habitat Degradation ◽  
Anthropogenic Activities ◽  
Ongoing Research ◽  
Management Techniques ◽  
Study Sites ◽  
Abundance And Distribution ◽  
Number Of Individuals ◽  
Sweep Net

Introduction: Odonates are used as bio-indicators for monitoring habitat degradation both on terrestrial and aquatic ecosystem because of their sensitivity to anthropogenic activities. They serve an important role in the ecological food chain by consuming aquatic larvae and being in turn consumed by birds and various amphibians. This study is part of the ongoing research on the diversity of Odonate species of Nigeria. The objective is to determine the abundance and distribution of odonates in Akwa Ibom State and to compare the species diversity across the various sites in Akwa Ibom State. Methodology: Akwa Ibom state was divided into six areas namely Ikot Akpaden, Obio Akpa, Ikot Okoro, Ikot Udofia, Urua Udofia and Obio Ndot using biotypes and a study site was randomly selected in each area. Adult members were captured using a sweep net and were preserved for identification using morphological features. Results: A total of 767 odonates were collected at the six study sites representing 24 species, 16 genera and four families namely Libellulidae (77%), Coenagrionidae (21%), Calopterygidae (>1%) and Chlorocyphidae (>1%). Most of the species collected were members of family Libellullidae (77%) with Palpopleura lucia having the highest occurrence (41%) and found in all the sites. Family Calopterygidae and Chlorocyphidae had less than 1% population of the total individuals collected. Ikot Okoro had the highest number of individuals (238) and the least evenness (e^H/S=0.3292) while Ikot Akpaden, which had the least effect of anthropogenic intrusion had the largest diversity of Odonata species (H’=2.387). Obio Ndot had the most evenly distributed Odonata species (e^H/S=0.8028). There was no statistical difference in the occurrence of dragonflies across all study sites (p= 0.238). Conclusion: The high occurrence of family Libellulidae which are anthropogenic tolerant, and the absence of more highly localized species indicate that most of the study sites have been degraded and may not be fit for species with narrow niches. It is therefore vital to conserve the Odonata community by implementing proper forest management techniques.

scholarly journals Orchid bee fauna responds to habitat complexity on a savanna area (Cerrado) in Brazil.

Sociobiology ◽  
2016 ◽  
Vol 63 (2) ◽  
pp. 819 ◽  
Author(s):  
Yasmine Antonini ◽  
Rodrigo Assunção Silveira ◽  
Márcio Oliveira ◽  
Cristiane Martins ◽  
Reisla Oliveira
Keyword(s):  
Species Richness ◽  
Species Diversity ◽  
Habitat Complexity ◽  
Habitat Structure ◽  
Dominant Species ◽  
Large Range ◽  
Physical Structure ◽  
High Complexity ◽  
Orchid Bee ◽  
Species Richness And Abundance

Habitat structure and complexity may broadly affect the diversity and composition of a variety of fauna in terrestrial systems. Here we investigated responses of orchid bee assemblages to habitat complexity, with the aim of assessing complexity as a useful surrogate for species diversity of this group. We test the following hypotheses: (i) There is a greater species richness and abundance of orchid bee in sites with high habitat complexity than lower habitat complexity; (ii) High habitat complexity sites have a different species composition of orchid bee than lower habitat complexity sites. For the purposes of our study, we defined habitat complexity as the heterogeneity in the arrangement in physical structure of habitat (vegetation), although there are a large range of operational definitions in the literature. As result, orchid bee species richness was higher in high complexity areas while community composition was not affected by habitat complexity, because Euglossa melanotricha and E. leucotricha were the dominant species, occurring in both environments. Habitat complexity, measured as a function of differences in multiple strata in forests, may be of great worth as a surrogate for the diversity of a range of arthropod groups including orchid bees. 

scholarly journals Modelling of rare plant species diversity changes by anthropogenic factors in meadow steppes of the Southern Opillya

2017 ◽  
pp. 133-142
Author(s):  
Dmytrash-Vatseba I.
Keyword(s):  
Species Diversity ◽  
Rare Species ◽  
Habitat Degradation ◽  
Rare Plants ◽  
Anthropogenic Factors ◽  
Species Number ◽  
Rare Plant ◽  
Cumulative Impact ◽  
Plant Richness ◽  
Negative Factors

Nowadays, area decrease and pastoral digression enhance are determinative factors for the extinction of rare plants populations. Making their cumulative impact on rare fraction of meadow steppes, these negative factors govern 74.4 % of habitats richness in the Southern Opillya. Two models were built to demonstrate the process of rare species number reduction under stress of the negative factors. Model I (regression model) displays a graduate ten times reduction in rare plant diversity rate with increasing of the factors intensity. Model II was developed based on generalized dataset of rare species number in habitats. It reveals an abrupt reduction of rare plant richness at the very beginning of habitat degradation, also at the last stages of this process. A species composition of rare fraction of flora for meadow steppes at different degradation level is presented.

Species diversity and distribution of seagrasses from the South Andaman, Andaman and Nicobar Islands, India

2018 ◽  
Vol 61 (3) ◽  
pp. 225-234 ◽  
Author(s):  
M. Savurirajan ◽  
Jawed Equbal ◽  
Raj Kiran Lakra ◽  
Kunal Satyam ◽  
Ganesh Thiruchitrambalam
Keyword(s):  
Species Diversity ◽  
Fine Sand ◽  
Shoot Density ◽  
The South ◽  
Anthropogenic Pressures ◽  
Thalassia Hemprichii ◽  
Coral Rubble ◽  
Coral Sand ◽  
South Andaman ◽  
Cymodocea Rotundata

AbstractA survey was conducted with the objective to study seagrass distribution, bed size and shoot density in different substrata of the South Andaman Islands. A total of 231 seagrass sites were observed during the study, in which a total of eight species were found. The South Andaman region exhibited the highest species diversity followed by Havelock, Little Andaman and Neil Islands. Eleven continuous seagrass bed were noted during the study which were confined to three different types of substrata: sand only; sand mixed with coral sand and coral rubble; sand mixed with mud.Thalassia hemprichiiandCymodocea rotundatawere found in dense canopies and covered large areas associated with sand and coral rubble.Halophila beccariishowed moderate abundance in muddy substrata andHalodulespp. grew in fine sand. The highest shoot density was recorded at Haddo, followed by Vijaya Nagar and Chidyatapu, contributed mostly byHalodulespp. In general, seagrass diversity and distribution were mainly influenced by the percentage composition of sand. The authors recommend that the seagrass meadow of Haddo should be considered for conservation priority because of multiple anthropogenic pressures, such as sewage input, dumping of solid wastes on the shoreline and anchoring of boats.

Sign in / Sign up

Export Citation Format

Share Document