Seasonal Variation In Diversity Research Articles

Interactions between mangrove soil, water, and microbes in degraded, natural, and restored tropical coastline ecosystems

ABSTRACT The interactions among soil, water, and microbes are unique and fundamental in mangrove forests. We examined and compared the physicochemical parameters of soil (pH, Organic Carbon (OC), Electrical Conductivity (EC), N, P, K, Mg, Ca, S, Fe, Zn, Cu, and Mn) and water (pH, temperature, Total Dissolved Solids (TDS), EC) as well as microbial diversity and abundance in nine natural, degraded, and restored mangrove ecosystems along Guyana’s coastline. Sampling was done using a randomized block design for one year in two seasons. Significant differences, correlations (p < 0.05, R > 0.75) and regressions in water and soil parameters were documented for the natural ecosystems and restored ecosystems in both seasons. Additionally, microbial abundance was greater in the restored ecosystems, while seasonal variations in diversity were seen in the degraded and restored ecosystems. Our study lends some credence to the idea that ecosystem type and seasonality can influence soil, water, and microbial interactions, which can ultimately affect mangrove biodiversity.

Reconnoitre on ichthyofauna of Mahanadi River of India: shifting diversity down the river continuum and linking ecological traits with patterns in biodiversity.

Anthropogenic alterations have paramount impacts on the alpha and beta diversity of aquatic resources, and fishes are predominantly susceptible to such impacts. Mahanadi River, one of the major peninsular rivers of India, has abundant fish resources, which play a significant role in supporting the fishers' livelihoods. The exploratory study in the river conducted for three consecutive years recorded 148 species under 53 families. Cyprinids dominated the fish diversity with 41 species, followed by Bagrids (9) and Sciaenids (7). One hundred-one species under 29 families were reported from the freshwater stretch. With a total of 111 species reported under 48 families, the estuarine and tidal freshwater stretch was more speciose, due to marine migrant species which advent the estuarine and tidal freshwaters stretch for breeding and feeding purposes. Tikarpara, a conserved site within a sanctuary, was the most species-diverse as well as a species-even site. The study also recorded the extension of the distributional range of 3 fish species and also 4 exotic species from the river. The seasonal variations in diversity indicated that the deviations were not prominent in freshwater sites, whereas in tidal brackish water sites, species richness was relatively higher in post-monsoon, and species evenness was higher during monsoon. Taxonomic distinctness test showed that the average taxonomic distinctness was high for tidal estuarine locations as they harbour taxonomically distant fishes. The hierarchical clustering of sites showed the inordinate effect of river gradient and fragmentation on the fish community structure. Analyzing the key drivers of the assemblage structure of the entire river, salinity was the major deterministic factor, and within the freshwater stretch, the major influences were depth, transparency, and specific conductivity. The study concluded that, despite all of its ecological stresses, Mahanadi still supports rich fish diversity, yet there is a notable shift in the fish community structure. There is a need for integrating molecular and morphological tools for the taxonomic revision of many genera and species for proper in situ and ex situ conservation measures and to formulate future biodiversity management plans addressing to reduce the impacts of the ecological threats.

Composition and diversity of fish assemblages along a shallow beach of a neotropical coastal lagoon

Coastal lagoons are inland water bodies connected to the sea and influenced by freshwater discharge, so these environments undergo constant changes in physical–chemical water characteristics. Transitional environments are important for promoting breeding, refuge, and food areas, besides serving as possible nursery habitats for fish species. In the present study, we analyzed the structure of the fish assemblages in a shallow marginal area of Mirim Lagoon, which belongs to the Laguna Estuarine System (LES), by seasonally evaluating the composition, structure, and diversity of the assemblages. Fieldwork was carried out between September 2017 and August 2018 with three monthly replicates using a beach seine net. Analyses were conducted to highlight the general patterns of the assemblages and to verify seasonal variations in composition, abundance, and diversity. The common species were defined using a species abundance curve, while the seasonal variation in diversity was evaluated using integrated rarefaction and extrapolation curves that correspond to the three orders of Hill numbers. The differences in the specific seasonal composition were indicated by dbRDA and the existence of statistical differences was tested using a PERMANOVA. In total, 3,556 individuals distributed in 16 families and 26 species were caught, with the predominance of Atherinella brasiliensis, Eucinostomus melanopterus, Coptodon rendalli, Eucinostomus argenteus, Mugi lliza, Anchoa tricolor, and Achirus lineatus that represented approximately 98% of the total. Regarding seasonality, the highest abundance was caught in the winter, while the lowest abundance was caught in autumn. The PERMANOVA indicated differences between spring and autumn and between autumn and winter. The main differences between these seasons are associated with the number of individuals caught, species abundance, and species composition. The presence of juveniles of several fish species, especially non-resident species, demonstrates the importance of the shallow area of Mirim Lagoon as a breeding, growth, and protection site that serves as a possible nursery habitat for these species.

Seasonal variation in diversity of Phytoplankton of Komen lake in Meghalaya, India

Seasonal variation in diversity of Phytoplankton of Komen lake in Meghalaya, India

Seasonal diversity of spider assemblages (Araneae: Arachnida) in the “Guillermo Piñeres” Botanical Garden, Turbaco–Colombia

ABSTRACT Climatic seasons have been shown to determine the temporal fluctuations in species communities of different ecosystems. Here, we assessed the diversity of spider assemblages in dry, transition and rainy seasons in the “Guillermo Piñeres” Botanical Garden (GPBG), Turbaco, Colombia. We collected spider assemblages between June 2018 and April 2019 through standardized day and night sampling methods for tropical ecosystems: looking up, looking down, beating and leaf litter sieving. In total, we collected 1585 individuals, belonging to 28 families and 112 (morpho) species. We calculated the effective species richness (Hill numbers) to evaluate the changes in diversity across seasons and used clustering and ordination methods (Jaccard index-based nMDS) to identify differences in the composition of the assemblages. Also, we compared the abundance and species richness of predatory guilds of the three seasons. The transition season showed the highest diversity with 94 morphospecies, an effective number of species of 48.7 and a dominance of 32.4 effective species. The clustering and ordination methods grouped the sampling events into three groups, each corresponding to a climatic season. The most abundant guild was the orb web weavers, with the highest value in the rainy season, while “other hunters” were the most species rich. Our results indicate that the spider assemblages in GPBG present a seasonal variation in diversity, probably influenced by climatic conditions. Understanding how these seasonal changes occur is necessary to develop forest management strategies for monitoring and management projects on the conservation of species assemblages according to the Convention on Biological Diversity.

Seasonal variations in diversity and the relative abundance of Odonata naiads from the temporary pools in Basrah Province-Southern of Iraq

This study aimed to investigate the monthly changes in the diversity and abundance of Odonata naiad's species for the period from December 2017 to November 2018 from three temporary pools in different areas of Basrah Province, including Abu Gossra-Abu Al-Kassib District (station 1), Al-Masehab- Al-Hartha district (station 2) and Al-Jalal - Al-Madina District (Station 3). Some environmental factors were measured, as water temperatures ranged between (12-38 ° C) while the salinity ranged between (1.2-14 ‰). Ten species of Odonata naiads were recorded, including eight species of Suborder Anisoptera and two species of Suborder Zygoptera. The highest diversity of naiads (9 species) was in St.1 and St.2, and the lowest diversity (8 species) was in St.3. Statistical analysis showed significant effect of environmental factors on the abundance of naiads during sampling period between stations and months. The highest relative abundance was 70% for Crocothemis servilia during January, while the lowest relative abundance was 0.98. % for Diplacodes lefebvrei during April. Environmental indexes of Anisoptera naiads in Basrah showed that their communities are poor in diversity and turbulent, balanced or semi balanced according to the standard values. Jacquard index showed the highest qualitative similarity between St.2 and St.3, and the lowest between St.1 and St.2.

Seasonal variation in the diversity of flowering orchids at Santa Catarina Lachatao, Oaxaca, Mexico

Background: Orchidaceae represents around 7.1-8.52 % of the angiosperms known in the planet. In Mexico, orchids are the third family more diverse, and Oaxaca is the state with the highest richness in the country. Orchids are widely distributed in tropical environments, but they are also distributed in temperate forests, where they have been scarcely studied.&#x0D; Questions: What is the diversity of orchid species at the locality of Santa Catarina Lachatao? Which subfamilies and growth forms are distributed at that locality? Do the community of orchids flowers differentially between seasons?&#x0D; Studied species: Species of the Orchidaceae family.&#x0D; Study site and dates: Santa Catarina Lachatao, Oaxaca, 2017-2018.&#x0D; Methods: Orchids were collected monthly throughout a year. Collected specimens were identified. Richness, abundance and diversity index were estimated for the whole flowering community, and per subfamily and growth form. These parameters were compared between seasons.&#x0D; Results: The community of orchids was composed by 4,933 flowering individuals from 74 species from the subfamilies Epidendroideae and Orchidoideae. Orchids with terrestrial, epiphyte, and rupicolous growth forms were collected. Total diversity index and species composition varied between seasons. Seasonal variation in abundance, diversity and species composition per subfamily and per growth form was also detected.&#x0D; Conclusions: Orchid diversity at the locality is high (9.68 % of the richness recorded for Oaxaca), and varies between seasons. The high species richness, the endemisms and endangered species found, call to take prompt actions to protect and manage the forest to assure its conservation and the diversity within it.

Seasonal variations in the diversity and structure of decapod communities in the changing hydrological scenario of the northwest African upwelling

Multidisciplinary surveys conducted on-board RV Dr Fridtjof Nansen in the northwest Africa region during November 2011 and June 2012 allowed exploration for the first time of seasonal variations in diversity and structure of decapod communities inhabiting the changing hydrological scenario of the shelf and upper slope off Mauritania (20–750 m depth). Decapods were gathered with a commercial bottom trawl at 95 stations, 39 of which were visited in both surveys. In addition, 249 oceanographic profiles and 95 sediment samples were collected. Shelf and slope assemblages, respectively characterized by the dominance of benthic (63 species) and swimming decapods (37 species), were segregated at 100–150 m depth, coinciding with the shelf-break and the hydrological frontier separating the surface mixed layer from the deeper water masses. The assemblages showed a certain stability in their structure but significant seasonal differences in their composition. Abundance and biomass, and in particular specific richness, were strongly correlated with depth in the case of swimming decapods, which were clearly dominant during the warm season, especially in the southern zone. The most significant seasonal variations were mainly due to the Penaeidae family and its associated species, Parapenaeus longirostris (Lucas, 1846). The latitudinal decreasing trend in upwelling permanence and productivity toward the south, responding to the strength and displacement of trade winds along the Mauritanian coast, which are observable at the surface and sea-bottom, were the main reason explaining the seasonal variations observed in the distribution patterns and assemblages structure of Mauritania decapods.

&lt;b&gt;Stream macro-invertebrate diversity of the Phobjikha Valley, Bhutan&lt;/b&gt;

Macro-invertebrates form an integral part of aquatic systems, and assessment of macro-invertebrate communities is one of the best ways to monitor the health of a stream. Despite this, stream monitoring of macro-invertebrates has been extremely limited in Bhutan. A study was conducted to generate baseline information on macro-invertebrate diversity in the Phobjikha valley, covering community composition and seasonal variation in diversity during post and pre-monsoon seasons. From a total of 244 units sampled in streams, 50 families from 13 orders were recorded. The dominant order overall was Ephemeroptera (31%), which also dominated the pre-monsoon assessment (33%), while Trichoptera (39%) dominated the post-monsoon assessment. The pre-monsoon assessment recorded two additional orders, Caenogastropoda and Veneroida. There was no significant difference in diversity between the post-monsoon and pre-monsoon assessments (p˃0.3), but a significant difference in species diversity between seasons was observed in pools and riffles. Physicochemical parameters indicated that pH, electrical conductivity and salinity were within favorable ranges for macro-invertebrates. Further studies of other habitats in different seasons will produce a more comprehensive understanding of macro-invertebrate diversity.

Seasonal variation in diversity of marine benthic invertebrates leads to a positive species-genetic diversity correlation (SGDC)

Seasonal variation in diversity of marine benthic invertebrates leads to a positive species-genetic diversity correlation (SGDC)

Seasonal Variations in Diversity and Abundance of Odonata at Sawanga-Vithoba Lake, India

Seasonal Variations in Diversity and Abundance of Odonata at Sawanga-Vithoba Lake, India

Records of the Cave-Dwelling Bats (Mammalia: Chiroptera) of Hispaniola with an Examination of Seasonal Variation in Diversity

Despite a long history of scientific collection of bats, Hispaniola remains the least studied island of the Greater Antilles. Using standardized trapping methods during the wet and dry season at four major caves — Honda de Julian, La Chepa, Los Patos, and Pomier #4, we sampled a total of 1,472 individuals in four families, 11 genera and 12 species (of 18 recorded for the island). We report significantly fewer captures on the second night of sampling. We document seasonal variation in abundance of Macrotus waterhousii, Monophyllus redmani, and Artibeus jamaicensis, that results in 1–4 more species captured in the wet season. Additionally, singleton captures at all caves except for Honda de Julian produced wide confidence intervals in estimates of richness. Finally, we highlight the role of caves as major ecosystems for maintaining Hispaniolan mammal biodiversity. The high diversity recorded at La Chepa, together with possible declines at the historically very diverse Los Patos, highlight the conservation i...

Seasonal variation in diversity and abundance of understorey birds in Bunduki Forest Reserve, Tanzania: evaluating the conservation value of a plantation forest

Plantation forests generally support lower bird diversity than natural forests. However, in some instances the plantations have been found to provide suitable habitat for a number of bird species. In the Eastern Arc Mountains, there is limited knowledge how understorey birds, some of which make seasonal altitudinal movements, use plantations. Using mist netting we assessed seasonal use of the plantation forest by the understorey bird community in Bunduki Forest Reserve in the Uluguru Mountains. Species diversity and capture rates were significantly higher during the cold season than during the hot season possibly due to seasonal altitudinal migration by some species. The use of plantations by those species that make seasonal altitudinal movements shows that plantation forests can enhance indigenous biodiversity by enabling connectivity between two or more natural forest patches. Our findings suggest that in a situation where there is no natural forest, an exotic plantation with suitable indigenous understorey cover can help in protection of birds, including endemic and near-endemic species.

Bird Community Diversity in three Habitat Types in an Ecological Corridor in the Atlantic Forest of Misiones Province, Argentina

The Atlantic Forest is one of the most threatened biodiversity hotspots in the world due to habitat fragmentation. Restoration and connectivity of forest fragments are crucial to maintain viable populations of forest-dependent species. During winter and summer, we studied the bird diversity, its components and composition (including specialist and generalist species) in three different vegetation types: mature forest (MF), secondary forest (SF) and grassland (G) of an ecological corridor in Misiones, Argentina. We determined the influence of alpha diversity (of each habitat) and beta diversity (species turnover between habitats) on gamma diversity (regional diversity in the corridor), to provide conservation management recommendations. MF showed the highest values of bird diversity, richness, evenness and abundance, followed by SF and G, in both seasons. Only MF showed a possible seasonal variation in diversity and richness. The species composition of SF was similar to MF. However, G, where pasture specialist and edge species were the most common species recorded (70% of its avifauna), had very low similarity to MF, where the most forest specialist species were found (53%). As alpha diversities were higher than beta values, the bird diversity in the studied corridor mainly resulted from the diversity in each vegetation type, in both studied seasons. We therefore recommend preservation of both MF and recovering SF due to their high bird diversity and the presence of forest-dependent, threatened and endemic bird species. We also urge the creation of ecological corridors between protected forest remnants of the Atlantic Forest.

Spatial and seasonal variation in diversity and structure of microbial biofilms on marine plastics in Northern European waters.

Plastic pollution is now recognised as a major threat to marine environments and marine biota. Recent research highlights that diverse microbial species are found to colonise plastic surfaces (the plastisphere) within marine waters. Here, we investigate how the structure and diversity of marine plastisphere microbial community vary with respect to season, location and plastic substrate type. We performed a 6-week exposure experiment with polyethylene terephthalate (PET) bottles in the North Sea (UK) as well as sea surface sampling of plastic polymers in Northern European waters. Scanning electron microscopy revealed diverse plastisphere communities comprising prokaryotic and eukaryotic microorganisms. Denaturing gradient gel electrophoresis (DGGE) and sequencing analysis revealed that plastisphere microbial communities on PET fragments varied both with season and location and comprised of bacteria belonging to Bacteroidetes, Proteobacteria, Cyanobacteria and members of the eukaryotes Bacillariophyceae and Phaeophyceae. Polymers sampled from the sea surface mainly comprised polyethylene, polystyrene and polypropylene particles. Variation within plastisphere communities on different polymer types was observed, but communities were primarily dominated by Cyanobacteria. This research reveals that the composition of plastisphere microbial communities in marine waters varies with season, geographical location and plastic substrate type.

Seasonal variations in diversity and abundance of surface ichthyoplankton in the northern South China Sea

The objective of this study was to investigate the seasonal variations of ichthyoplankton diversity and abundance in the northern South China Sea based on the data collected during summer, winter and spring. In total, 95 taxa of larval fishes were identified. The greatest number of species was recorded in spring, followed by summer and winter. The number of species was distributed mainly in the coastal waters from the east of Leizhou Peninsula to the southeast of Hainan Island during the surveyed periods of summer and spring, but in the offshore waters during winter. The abundance of larval fish was lowest in winter, increased in spring, and reached the maximum in summer. High abundance of larval fish was generally restricted to coastal waters with the isobaths less than 50 m. Seasonal variations of larval fish richness, abundance and diversity index were significant (P<0.001). Carangidae was the most common and abundant taxon in summer and winter, while Sardinella sp., Thrissa mystax and Leiognathus sp. were dominant in spring. High diversity and abundance of larval fish might be attributed to increased temperature and coastal upwelling in spring and summer.

Seasonal Variation in Diversity and Abundance of Butterfly at Sawanga Vithoba Lake Area District Amravati, Maharashtra India

Seasonal Variation in Diversity and Abundance of Butterfly at Sawanga Vithoba Lake Area District Amravati, Maharashtra India

Impact of the valley flooding upon the abundance and diversity of the reef fishes in Wadi El-Gemal protected area, Red Sea, Egypt

This study was conducted in Wadi El-Gemal using visual census technique in order to study the composition of the fish community in the area and to evaluate the effect of the flooding drain on the abundance and diversity of reef fishes. The area in front of the flooding drain was divided into three transects according to their proximity to the drain. Each transect was divided into three zones; reef flat, reef edge and reef slope and fishes were counted at each zone. A total of 4388 fish constituting 94 species in 23 families of coral reef fish were recorded. The highest number of species was recorded in the reef slope of transect two (85), while the lowest was present at the reef flat (11). The highest number of individuals was recorded in the reef slope, where 1002 fish were counted, while the lowest number was in the first transect (86). There were no great seasonal variations in diversity but slight differences were noted in abundance of fishes. The highest diversity was observed in the fall with 88 species and the richness was 11.9 while the lowest was in winter with 82 species and the richness was 10.7. Number of species as well as number of fish increases as the distance from the mouth of the valley increases.

Marked seasonality of aerobic anoxygenic phototrophic bacteria in the coastal NW Mediterranean Sea as revealed by cell abundance, pigment concentration and pyrosequencing of pufM gene

The abundance and diversity of aerobic anoxygenic phototrophs (AAPs) were studied for a year cycle at the Blanes Bay Microbial Observatory (NW Mediterranean) and their potential links to an array of environmental variables were explored. Cell numbers were low in winter and peaked in summer, showing a marked seasonality that positively correlated with day length and light at the surface. Bacteriochlorophyll a concentration, their light-harvesting pigment, was only detected between April and October, and pigment cell quota showed large variations during this period. Pyrosequencing analysis of the pufM gene revealed that the most abundant operational taxonomic units (OTUs) were affiliated to phylogroup K (Gammaproteobacteria) and uncultured phylogroup C, although they were outnumbered by alphaproteobacterial OTUs in spring. Overall, richness was higher in winter than in summer, showing an opposite trend to abundance and day length. Clustering of samples by multivariate analyses showed a clear seasonality that suggests a succession of different AAP subpopulations over time. Temperature, chlorophyll a and day length were the environmental drivers that best explained the distribution of AAP assemblages. These results indicate that AAP bacteria are highly dynamic and undergo seasonal variations in diversity and abundance mostly dictated by environmental conditions as exemplified by light availability.

Seasonal changes in caddis larvae assemblages in river-floodplain habitats along a hydrological connectivity gradient

In order to assess the impact of seasonality versus connectivity on the ecological quality of the Lower Rhine river-floodplain habitats, we studied the seasonal variation in diversity and species assemblages of caddis larvae by monthly sampling of the littoral zone of four water bodies over a lateral connectivity gradient. Seasonal variation in diversity showed a general pattern in these floodplain habitats and could be related to caddisfly life history and habitat preferences. Despite this seasonal variation, caddis larvae species assemblages in the water bodies appeared to be rather stable and could be firmly related to the position of their habitats over the connectivity gradient. The main channel (lotic habitat) was clearly separated from the lentic water bodies, and also the sparsely vegetated water bodies from the well-vegetated water bodies. It is concluded that the impact of connectivity, and related parameters such as stream velocity and vegetation coverage, outweighed the impact of season on the caddis larvae assemblages.