GRUPOS FUNCIONAIS FITOPLANCTÔNICOS EVIDENCIAM DIFERENÇAS AMBIENTAIS EM UMA PLANÍCIE DE INUNDAÇÃO TEMPERADA

Floodplain environments have high biodiversity and provide many ecosystem services maintained by the flood pulses. The phytoplankton is essential to the functioning of these ecosystems, acting upon primary productivity and biogeochemical cycles. We evaluated phytoplankton in a river-lake flood system (Illinois River floodplain-USA) during a hydrological cycle and compared the taxonomic (species) and functional (morphologic-based functional groups – MBFG) approaches. As expected, greater species richness was registered in the river and higher biovolume in the lake, as well as the predominance of different MBFGs in each environment. Furthermore, seasonality drove richness and biovolume temporal variation due to the higher water levels during spring. The MBFG IV (i. e. without specialized traits), V (phytoflagellates) and VI (diatoms) were more important for richness and biovolume in both environments. We reinforce the fundamental role of the hydrodynamics characteristics, with higher phytoplankton biovolume values in the lake. Using MBFG resulted in a better explanation to the phytoplankton-environment relationship. Constant water column mixture and high turbidity selected species with traits (e.g. small size, presence of silica) specifically adapted to these conditions.

Download Full-text

An assessment of the factors determining rotifer assemblage in river-lake systems: the effects of seasonality and habitat

Zoologia (Curitiba) ◽

10.3897/zoologia.36.e24191 ◽

2019 ◽

Vol 36 ◽

pp. 1-5

Author(s):

Moacyr Serafim-Júnior ◽

Gilmar Perbiche-Neves ◽

Fabio Lansac-Toha

Keyword(s):

Species Richness ◽

Aquatic Macrophytes ◽

Hydrological Cycle ◽

High Water ◽

Water Levels ◽

Natural Environments ◽

Ecological Attributes ◽

Lake System ◽

The Mean ◽

Lake Systems

Zooplankton exhibit several trends of variation in space and time, and these trends can be more evident in natural environments without anthropic perturbations. Examples of anthropic factors are climate change, eutrophication and construction of reservoirs. This study evaluated the influence of three factors – seasonality, type of environment and the presence of aquatic macrophytes – on various ecological attributes of rotifers in a river-lake system located in the Paraná River floodplain. Monthly samplings were conducted during 1993 and 1994. The mean species richness per sample was 60 species. The seasonality and the type of environment influenced the ecological attributes of rotifer assemblages, while the presence or absence of aquatic macrophytes did not. Species richness was highest in the lake system and during the months when water levels were low. Multivariate analysis indicates a small group of species associated with the low water-level phase. In contrast, many species were associated with high water levels or increasing water levels. The seasonal variation of hydrological cycle and the type of environment are the most important factors for rotifer structure in natural conditions.

Download Full-text

Flood pulse effects on multispecies fishery yields in the Lower Amazon

Royal Society Open Science ◽

10.1098/rsos.150299 ◽

2015 ◽

Vol 2 (11) ◽

pp. 150299 ◽

Cited By ~ 34

Author(s):

Leandro Castello ◽

Victoria J. Isaac ◽

Ram Thapa

Keyword(s):

Interannual Variability ◽

Complex Dynamics ◽

Flood Pulse ◽

Large River ◽

Fishing Effort ◽

Water Levels ◽

Fish Biomass ◽

River Floodplain ◽

River Floodplains ◽

Flood Pulses

Seasonally fluctuating water levels, known as ‘flood pulses’, control the productivity of large river fisheries, but the extent and mechanisms through which flood pulses affect fishery yields are poorly understood. To quantify and better understand flood pulse effects on fishery yields, this study applied regression techniques to a hydrological and fishery record (years 1993–2004) for 42 species of the Amazon River floodplains. Models based on indices of fishing effort, high waters and low waters explained most of the interannual variability in yields ( R 2 =0.8). The results indicated that high and low waters in any given year affected fishery yields two and three years later through changes in fish biomass available for harvesting, contributing 18% of the explained variability in yields. Fishing effort appeared to amplify high and low water effects by changing in direct proportion to changes in fish biomass available for harvesting, contributing 62% of the explained variability in yields. Although high waters are generally expected to have greater relative influence on fishery yields than low waters, high and low waters exerted equal forcing on these Amazonian river-floodplain fishery yields. These findings highlight the complex dynamics of river-floodplain fisheries in relation to interannual variability in flood pulses.

Download Full-text

The role of topography and soil characteristics in the relationship between species richness and primary productivity in a Kansas grassland

Transactions of the Kansas Academy of Science ◽

10.1660/0022-8443(2008)111[105:trotas]2.0.co;2 ◽

2008 ◽

Vol 111 (1 & 2) ◽

pp. 105-117 ◽

Cited By ~ 3

Author(s):

Cathy D. Collins ◽

Bryan L. Foster

Keyword(s):

Species Richness ◽

Primary Productivity ◽

Soil Characteristics ◽

The Relationship

Download Full-text

The importance of Antarctic krill in biogeochemical cycles

Nature Communications ◽

10.1038/s41467-019-12668-7 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 8

Author(s):

E. L. Cavan ◽

A. Belcher ◽

A. Atkinson ◽

S. L. Hill ◽

S. Kawaguchi ◽

...

Keyword(s):

Primary Productivity ◽

Fishery Management ◽

Antarctic Krill ◽

Carbon Sink ◽

Euphausia Superba ◽

Biogeochemical Cycles ◽

High Biomass ◽

Large Size ◽

Fishing Impacts

Abstract Antarctic krill (Euphausia superba) are swarming, oceanic crustaceans, up to two inches long, and best known as prey for whales and penguins – but they have another important role. With their large size, high biomass and daily vertical migrations they transport and transform essential nutrients, stimulate primary productivity and influence the carbon sink. Antarctic krill are also fished by the Southern Ocean’s largest fishery. Yet how krill fishing impacts nutrient fertilisation and the carbon sink in the Southern Ocean is poorly understood. Our synthesis shows fishery management should consider the influential biogeochemical role of both adult and larval Antarctic krill.

Download Full-text

Role of a simplified hydrological cycle and clouds in regulating the climate–biota system of Daisyworld

Tellus B ◽

10.3402/tellusb.v61i2.16846 ◽

2009 ◽

Vol 61 (2) ◽

Author(s):

Juan Fernando Salazar ◽

Germán Poveda

Keyword(s):

Hydrological Cycle

Download Full-text

Arthropod community structure in pastures of an island archipelago (Azores): looking for local–regional species richness patterns at fine-scales

Bulletin of Entomological Research ◽

10.1079/ber2004289 ◽

2004 ◽

Vol 94 (2) ◽

pp. 111-121 ◽

Cited By ~ 22

Author(s):

P.A.V. Borges ◽

V.K. Brown

Keyword(s):

Species Richness ◽

Regional Scale ◽

Local Scale ◽

Local Species Richness ◽

Β Diversity ◽

Arthropod Species ◽

Α Diversity ◽

Local Species ◽

Richness Patterns

AbstractThe arthropod species richness of pastures in three Azorean islands was used to examine the relationship between local and regional species richness over two years. Two groups of arthropods, spiders and sucking insects, representing two functionally different but common groups of pasture invertebrates were investigated. The local–regional species richness relationship was assessed over relatively fine scales: quadrats (= local scale) and within pastures (= regional scale). Mean plot species richness was used as a measure of local species richness (= α diversity) and regional species richness was estimated at the pasture level (= γ diversity) with the ‘first-order-Jackknife’ estimator. Three related issues were addressed: (i) the role of estimated regional species richness and variables operating at the local scale (vegetation structure and diversity) in determining local species richness; (ii) quantification of the relative contributions of α and β diversity to regional diversity using additive partitioning; and (iii) the occurrence of consistent patterns in different years by analysing independently between-year data. Species assemblages of spiders were saturated at the local scale (similar local species richness and increasing β-diversity in richer regions) and were more dependent on vegetational structure than regional species richness. Sucking insect herbivores, by contrast, exhibited a linear relationship between local and regional species richness, consistent with the proportional sampling model. The patterns were consistent between years. These results imply that for spiders local processes are important, with assemblages in a particular patch being constrained by habitat structure. In contrast, for sucking insects, local processes may be insignificant in structuring communities.

Download Full-text