scholarly journals The phytoplankton of Guanabara Bay, Brazil: I. historical account of its biodiversity

2010 ◽  
Vol 10 (2) ◽  
pp. 271-293 ◽  
Author(s):  
Maria Célia Villac ◽  
Denise Rivera Tenenbaum
Keyword(s):  
Skeletonema Costatum ◽  
Abundant Species ◽  
Oxygen Depletion ◽  
Species Level ◽  
Frequency Of Occurrence ◽  
Guanabara Bay ◽  
Historical Account ◽  
Species Numbers ◽  
Time Variations ◽  
Technical Capability

This is a historical account of the biodiversity of phytoplankton in Guanabara Bay, Brazil. It is based on 57 publications that refer to sampling carried out between 1913 and 2004. The publications included are those with direct microscopic identification. Although 80% of the studies focus on ecological issues that tend to mention only the most abundant species, 24 publications provide comprehensive check-lists at the species level, especially of taxa > 20 μm. The inventory of species includes, to date, 308 taxa among 199 diatoms, 90 dinoflagellates, 9 cyanobacteria, 5 euglenophyceans, 1 chlorophycean, 1 prasinophycean, 1 silicoflagellate, and 2 ebriids. The most conspicuous species were the dinoflagellate Scrippsiella trochoidea and diatoms from the Skeletonema costatum complex. The first was the theme of the very first publication in the area (Faria 1914) that reported on its bloom associated with the mass mortality of fish due to oxygen depletion; it is still often found in high abundances (10(6) cell.L-1) in more protected areas. The second was long considered in the literature as a cosmopolitan and opportunistic species, until the recent discovery of cryptic species within the genus; taxonomic re-evaluation of local populations is, therefore, needed. Besides these two species, only other 25 species stood out in terms of frequency of occurrence and widespread distribution in the Bay, some known to be implicated in harmful blooms elsewhere. The biodiversity of dinoflagellates, especially within the Gymnodiniales, and that of other unidentified flagellates (Haptophyceae, Cryptophyceae, Prasinophyceae, Raphidophyceae) is largely underestimated because of the use of fixatives that distort/destroy diagnostic characters. From the initial inventory of 124 taxa published in 1917 and the subsequent additions in species numbers, one can have a false perception that the phytoplankton biodiversity has increased throughout the years, despite the overall increase in eutrophication observed in Guanabara Bay. The reason for this may be twofold: 1) it is an artifact caused by our progressively improving technical capability to detect and identify species and 2) the possible effects of eutrophication could be better perceived when the community structure is evaluated, that is, when space-time variations in the abundances of the populations (rather than just number of species) are also taken into account.

scholarly journals Neelipleona and Symphypleona (Collembola) from a Sampling in the Mesovoid Shallow Substratum of the Sierra de Guadarrama National Park (Madrid and Segovia, Spain): Taxonomy and Biogeography

Insects ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 266
Author(s):  
Enrique Baquero ◽  
Rafael Jordana ◽  
Vicente M. Ortuño
Keyword(s):  
National Park ◽  
Ecological Niche ◽  
Mediterranean Area ◽  
Abundant Species ◽  
Species Level ◽  
Surface Sampling ◽  
Mesovoid Shallow Substratum ◽  
The Mediterranean

Megalothorax minimus (Neelidae) and Sphaeridia pumilis (Sminthurididae) had already been identified in surface sampling from Sierra de Guadarrama. In Europe, Sminthurinus gisini (Katiannidae) seems to be associated with environments at specific altitudes, and has little representation in this sampling. Pygmarrhopalites custodum Baquero and Jordana sp. nov. (Arrhopalitidae) coexists with two previously identified surface occurring species of the same family (P. elegans and Arrhopalites caecus). However, P. custodum is more abundant, indicating that it occupies an ecological niche tending to troglophile in the mesovoid shallow substratum (MSS). Moreover, it is also more abundant in the MSS of higher altitude corresponding to the bioclimatic zones cryo-oro-Mediterranean and oro-Mediterranean supra forest. Allacma cryptica Baquero and Jordana sp. nov. (Sminthuridae), is another species that had not been previously detected on the surface in the study area. A. cryptica is an addition to a genus which has eight described species. Gisinurus malatestai (Sminthuridae) appears well represented in the MSS, being a species present very occasionally in the Mediterranean area. Two species of the genera Sminthurides (Sminthurididae) and Fasciosminthurus (Bourletiellidae) have been found, but they could not have been identified to the species level. Finally, a few specimens of Dicyrtomina minuta (Dicyrtomidae), an abundant species on the surface, have been captured.

scholarly journals Shifts in Diatom Dominance Associated with Seasonal Changes in an Estuarine-Mangrove Phytoplankton Community

2020 ◽  
Vol 8 (7) ◽  
pp. 528
Author(s):  
Fareha Hilaluddin ◽  
Fatimah Md. Yusoff ◽  
Tatsuki Toda
Keyword(s):  
Environmental Changes ◽  
Skeletonema Costatum ◽  
Sampling Period ◽  
Abundant Species ◽  
Dry Season ◽  
Northeast Monsoon ◽  
Diatom Species ◽  
Phytoplankton Abundance ◽  
Wet Season ◽  
Total Phytoplankton

A study on seasonal phytoplankton abundance and composition in a mangrove estuary, Matang Mangrove Forest Reserve (MMFR), Malaysia, was carried out to determine the phytoplankton structure in this ecosystem, and to identify potential indicators of environmental changes. Phytoplankton samples were collected bimonthly from June 2010 to April 2011, to cover both dry (June to October) and wet (November to April) seasons, at four selected sampling sites along the river. Diatoms showed the highest number of species (50 species) from a total of 85 phytoplankton species from 76 genera. Diatoms contributed more than 90% of the total phytoplankton abundance during the dry season (southwest monsoon) and less than 70% during the wet season (northeast monsoon) as dinoflagellates became more abundant during the rainy season. Two diatoms were recorded as dominant species throughout the sampling period; Cyclotella sp. and Skeletonema costatum. Cyclotella sp. formed the most abundant species (62% of total phytoplankton) during the dry period characterized by low nutrients and relatively low turbidity. Skeletonema costatum contributed 93% of the total phytoplankton in October, which marked the end of the dry season and the beginning of the wet season, characterized by strong winds and high waves leading to the upwelling of the water column. Massive blooms of Skeletonema costatum occurred during the upwelling when total nitrogen (TN) and total phosphorus (TP) concentrations were highest (p < 0.05) throughout the year. The abundance of diatom species during the wet season was more evenly distributed, with most diatom species contributing less than 12% of the total phytoplankton. Autotrophic producers such as diatoms were limited by high turbidity during the northeast monsoon when the rainfall was high. During the wet season, Cyclotella and Skeletonema costatum only contributed 9% and 5% of the total phytoplankton, respectively, as dinoflagellates had more competitive advantage in turbid waters. This study illustrates that some diatom species such as Cyclotella sp. and Skeletonema costatum could be used as indicators of the environmental changes in marine waters.

scholarly journals Seasonal Changes in Bird Assemblages of a Forest-Steppe Ecotone in North Patagonia

2018 ◽  
Author(s):  
Víctor R. Cueto ◽  
Cristian A. Gorosito
Keyword(s):  
Species Composition ◽  
Seasonal Variations ◽  
Bird Species ◽  
Abundant Species ◽  
Species Level ◽  
Forest Steppe ◽  
Total Abundance ◽  
Long Distance ◽  
North Patagonia ◽  
Different Seasons

AbstractWe evaluate seasonal variations at the community level, analyzing changes in species richness, species composition and total abundance, and at the species level, evaluating differences in breeding and molting seasonality among bird species in a forest-steppe ecotone of north Patagonia. The bird assemblage showed a low seasonal variation in richness and total abundance, but a great change in species composition between spring-summer and fall-winter. The change in species composition promoted few seasonal variations in richness and total abundance, because they were compensated by the presence of abundant species that visit the area in different seasons. At the species level, resident birds and short distance migrants tended to begin breeding earlier than long distance migrants, and birds began to molt body and flight feathers after breeding. Therefore, we found a low overlap of these two demanding activities. Our results highlight the importance of bird movements in response to seasonal variations in the availability of resources, which promote migration or local displacements of birds.Resumen. Cambios estacionales en los ensambles de aves en un ecotono bosque-estepa del norte de PatagoniaEvaluamos las variaciones estacionales a nivel comunitario, analizando la riqueza de especies, la composición de especies y la abundancia total, y a nivel de las especies, evaluando las diferencias en la estacionalidad reproductiva y de muda entre las especies de aves en un ecotono bosque-estepa del norte de Patagonia. El ensamble de aves mostró pocas variaciones estacionales en la riqueza y abundancia total, pero un notable cambio en la composición de especies entre la primavera-verano y el otoño-invierno. El cambio en la composición de especies promovió pocas variaciones estaciones en la riqueza y la abundancia total, porque fueron compensadas por la abundancia de las especies que visitan el área en las diferentes estaciones. A nivel de las especies, las aves residentes y migrantes de corta distancia tendieron a comenzar la reproducción antes que las migrantes de larga distancia, y las aves comenzaron la muda de plumas del cuerpo y del ala al finalizar la reproducción. Por lo cual encontramos una baja superposición de estas dos demandantes actividades. Nuestros resultados remarcan la importancia del movimiento de las aves en respuesta a las variaciones en la disponibilidad de recursos, que promueven la migración o el desplazamiento local de las aves.

scholarly journals DIVERSIDAD, ABUNDANCIA Y AMENAZAS DE LOS OCTOCORALES DE LA ISLA MALPELO, PACÍFICO ORIENTAL TROPICAL, COLOMBIA

2016 ◽  
Vol 40 ◽  
Author(s):  
Juan A. Sánchez ◽  
Carlos E. Gómez ◽  
Dairo Escobar ◽  
Luisa F. Dueñas
Keyword(s):  
Invasive Species ◽  
Transition Zone ◽  
High Mortality ◽  
Abundant Species ◽  
Disease Prevalence ◽  
Fungal Diseases ◽  
Frequency Of Occurrence ◽  
Deep Zone ◽  
Carijoa Riisei ◽  
Malpelo Island

During three expeditions to the island (2009 and 2010), the diversity, abundance and status of octocorals were explored. Seven species of octocorals were recorded: Leptogorgia alba, Pacifigorgia cf. lacerata, Pacifigorgia sp.1 y Pacifigorgia sp.2, Muricea cf. fruticosa, Muricea sp., and the invasive species Carijoa riisei. Octocorals form dense aggregations in rocky walls and cliffs, with higher abundances between 10 and 20 m, reaching up to 20 colonies m-2. The most abundant species was Pacifigorgia cf. lacerata with a dominance of more than 60 % and a frequency of occurrence of 100 % for all visited sites. According to depth, three well-defined zones were determined for most sites. A deep zone between 25 and 40 m with an exclusive dominance of L. alba, a shallow assemblage between 7 and 20 m dominated by Pacifigorgia spp., and a transition zone between 18 and 25 m with a mixture of L. alba and P. cf. lacerata. Surprisingly, during November 2009, diseases of possible fungal origin visibly affected populations of Leptogorgia and Pacifigorgia. Subsequently, during February 2010 the same populations of octocorals were monitored and up to 66 % of the colonies were already dead in some locations. Leptogorgia had a significant reduction at El Arrecife site, while Pacifigorgia cf. lacerata had high mortality at La Nevera and El Freezer sites, and a recovery in El Arrecife. There was a notable improvement in disease prevalence by July 2010 with less than 10 % of diseased colonies. The invasive species C. riisei was observed in La Catedral and El Monstruo bank. Thus, this information increases considerably the knowledge of octocorals on Malpelo Island and is the first warning of possible threats against local octocoral populations, such as fungal diseases and the invasive octocoral C. riisei.

Suprabenthic amphipods from the littoral zone of Barlovento, Venezuela: spatial distribution and seasonal variation

Crustaceana ◽  
2013 ◽  
Vol 86 (10) ◽  
pp. 1206-1223 ◽  
Author(s):  
I. Ortega ◽  
A. Martin
Keyword(s):  
Environmental Variables ◽  
Littoral Zone ◽  
Abundant Species ◽  
Spatial And Temporal Variation ◽  
Total Density ◽  
Frequency Of Occurrence ◽  
Wood Debris ◽  
Density And Biomass ◽  
Amphipod Density ◽  
Common Variable

Peracarid crustaceans are a very diverse benthic group and one of the dominant taxa within the suprabenthic community. The Barlovento beaches in Venezuela are characterised by large inputs of organic matter and an important assemblage of amphipods has been observed to thrive in this area. In this paper we describe the species composition of this amphipod assemblage along with their spatial and temporal variation and relationship with some environmental variables on four beaches (Agua Sal, Los Timones, Las Cabañas, Valle Seco). Results showed no significant differences in the amphipod community structure and total density of organisms regardless of the season (rainy and dry). From the 7569 amphipods collected, a total of 20 species were identified within 14 families and 17 genera. The species Apohyale media (Dana, 1953), Metatiron tropakis (J. L. Barnard, 1972) and Nototropis minikoi (A. O. Walker, 1905) were the most abundant species in terms of density, and the last two also in terms of frequency of occurrence. Differences in biomass were not significant at any level (season, beach and their interactions); however, the highest amphipod biomass throughout the year was observed at Valle Seco Beach with peaks in January, August and December coinciding with large accumulations of bryozoans and wood debris. Amphipod density and biomass had low correlation values with the environmental variables; the material caught in the suprabenthos net being the most common variable influencing the community.

scholarly journals Spatiotemporal dynamics of soil rotifers in a South-Bohemian beech forest

2009 ◽  
Vol 44 (8) ◽  
pp. 1027-1032 ◽  
Author(s):  
Miloslav Devetter
Keyword(s):  
Vertical Profile ◽  
Dominant Species ◽  
Diversity Index ◽  
Great Part ◽  
Abundant Species ◽  
Beech Forest ◽  
Soil Samples ◽  
Species Level ◽  
Fresh Litter ◽  
South Bohemia

The objective of this work was to determine seasonal variation and vertical distribution of the soil rotifer assemblage in a climax beech forest in South Bohemia. During 2005, soil rotifer was investigated to the species level. Soil samples of 10 cm² and 10 cm in depth were divided into five layers, which were processed separately. Thirty one rotifer species were identified during the investigation. Dominant species significantly changed throughout the seasons. The most abundant species were Encentrum arvicola and Wierzejskiella vagneri among the monogononts, and Adineta steineri, Ceratotrocha cornigera, Habrotrocha filum, Habrotrocha ligula, Macrotrachela plicata, Mniobia tentans, Mniobia incrassata and Mniobia granulosa among the bdelloids. Mean Shannon diversity index varied from 1.99 to 2.63. Total rotifer abundance varied from 212±63 to 513±127 10³ individuals m-2 along the year, with the highest numbers found in May, and the lowest in July. The great part of the community was concentrated in the upper (fresh litter) and second (partially decomposed litter) layers and significantly decreased in the soil vertical profile on all sampling dates. The highest rotifer density of 43 individuals g-1 was found in the upper layer in May.

Differences in rotifer communities in two freshwater bodies of different trophic degree (Lake Ohrid and Lake Dojran, Macedonia)

Biologia ◽  
2012 ◽  
Vol 67 (3) ◽  
Author(s):  
Orhideja Tasevska ◽  
Christian Jersabek ◽  
Goce Kostoski ◽  
Dafina Gušeska
Keyword(s):  
Trophic State ◽  
Eutrophic Lake ◽  
Abundant Species ◽  
Lake Ohrid ◽  
Structure Population ◽  
Keratella Cochlearis ◽  
Species Numbers ◽  
Freshwater Bodies ◽  
Occurrence Pattern ◽  
Rotifer Communities

AbstractWe investigated monogonont rotifers in two natural Macedonian lakes that greatly differ in age, size and trophic state: Lake Ohrid and Lake Dojran. A main characteristic of Lake Ohrid is the scarcity of nutrients and consequently a low level of primary production. Lake Dojran represents a typical eutrophic lake. Results clearly indicate that species numbers are negatively correlated with trophic degree. Qualitative analyses of rotifer compositions in Lakes Ohrid and Dojran showed the presence of 70 and 55 taxa, respectively. Rotifer assemblages differed in their community structure, population densities, and the occurrence pattern of dominant species. The density of rotifers increased with increasing nutrient concentration, varying from min. 0.67 ind. L−1 in June, 2006 to max. 8.2 ind. L−1 in July, 2004 in Lake Ohrid, whereas min. 28.8 ind. L−1 (in December, 2005) and max. 442.5 ind. L−1 (in September, 2005) were recorded in Lake Dojran. Gastropus stylifer and Keratella cochlearis were the most abundant species in the pelagic zone of Lake Ohrid, averaging monthly densities of 1.2 ind. L−1 and 0.6 ind. L−1, respectively, thereby contributing 29% and 15% to rotifer abundance. In contrast, Lake Dojran rotifers were dominated by Brachionus spp. Brachionus diversicornis and Brachionus calyciflorus f. amphiceros were most abundant, comprising 40% and 25% of the total rotifer density. These results corroborate our idea, that the trophic state is an important factor in determining the composition of rotifer communities.

Weed flora of South Africa 2: power shifts in the veld

Bothalia ◽  
1983 ◽  
Vol 14 (3/4) ◽  
pp. 961-965 ◽  
Author(s):  
M. J. Wells ◽  
V. M. Engelbregcht ◽  
A. A. Balsinhas ◽  
C. H. Stirton
Keyword(s):  
Invasive Species ◽  
Threatened Species ◽  
Species Level ◽  
Indigenous Species ◽  
Weed Species ◽  
Power Shifts ◽  
Species Numbers ◽  
Weed Flora ◽  
Family Level ◽  
The Impact

This paper, the second in a series analysing data from the National Weed List, concentrates on weedy changes that affect the indigenous flora. The incidence of weediness and of threatened species is used as an indication of success or failure of families under prevailing conditions of disturbance. The resulting power shifts between indigenous families and the impact of exotic weeds on the situation are reviewed. Many power shifts are taking place between indigenous species in the veld. Superficially it seems as though a relatively few invasive species are displacing a larger number of threatened species, but evidence from Natal points to more species increasing than decreasing under conditions of over-utilization. Amongst small families power shifts are almost as prevalent and important as at species level. Seventeen small families have over 20% indigenous weed species. Thirty small families have over 20% threatened species, and 21 small families have had their species numbers bolstered by more than  20% by exotic weeds. A very few large and medium-sized families contain over 50% of our weeds and our threatened species. It is mostly temperate (Cape) families that are under pressure relative to more tropical families. This trend is echoed at sub-family level within the Fabaceae.

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