scholarly journals Phytoplankton assemblages in Lake Orta: has functional structure recovered in one of the largest acidic lakes in the world?

2016 ◽  
Vol 75 (s2) ◽  
Author(s):  
Giuseppe Morabito
Keyword(s):  
Functional Groups ◽  
Diversity Indices ◽  
Taxonomic Composition ◽  
Ecological Niches ◽  
Phytoplankton Species ◽  
Phytoplankton Assemblages ◽  
Lake Maggiore ◽  
Acidic Lakes ◽  
Physical Features ◽  
She Analysis

Lake Orta (Northern Italy) became one of the world’s largest acidic lakes, following industrial pollution, beginning in the late 1920s. Prior to pollution, Lake Orta supported a rich and diversified phytoplankton community dominated by diatoms, cyanobacteria and dinoflagellates. Their taxonomic composition was comparable to that of the nearby Lake Maggiore, which provides a useful reference comparison. After pollution, Lake Orta was so acidic and contaminated with trace metals that only a few tolerant phytoplankton species persisted, supplemented by sudden and short living outbursts of occasional colonists. The lake was limed in 1989-1990. This has permitted the gradual recovery of its chemistry and biology, and many phytoplankton species that inhabit Lake Maggiore are now re-appearing in Lake Orta. I tested the two hypotheses that Lakes Orta and Maggiore would now have a similar phytoplankton taxonomic assemblages, and similar diversity of functional groups given their similar morphometry, physical features and trophic states. The two hypotheses were tested by comparing the phytoplankton assemblages of lakes Maggiore and Orta for the first 10 years after liming, i.e. 1990 to 2001. Phytoplankton was classified according the Reynolds' Morpho Functional Groups and five diversity indices were calculated (<em>S</em>, number of units; <em>H</em>, Shannon-Wiener; <em>E</em>, evenness; <em>D</em>, dominance; <em>J</em>, equitability). SHE analysis (an analysis of diversity changes based on the relationship among species richness (S), H Index (H) and evenness (E)) was also carried out, in order to compare the long term trend of both functional groups and taxa biodiversity. Both taxonomic and the functional composition differed in the two lakes, likely because chemical quality have played a role in <em>taxa</em>selection. Moreover, it was quite clear that, during the first post-liming decade, Lake Orta’s phytoplankton was characterized by low diversity and evenness and by marked year-to-year fluctuations. However, SHE analysis showed that the colonization rate was higher in Lake Orta than in Lake Maggiore, and that the environmental modifications caused by the liming were opening new ecological niches, allowing some colonists to thrive in the changing, albeit still unusual chemical environment of the lake.<p> </p>

scholarly journals Species presence frequency and diversity in different patch types along an altitudinal gradient: Larix chinensis Beissn in Qinling Mountains (China)

2016 ◽  
Author(s):  
Minyi Huang ◽  
Renyan Duan ◽  
Shixiong Wang ◽  
Zhigao Wang ◽  
Weiyi Fan
Keyword(s):  
Functional Groups ◽  
Altitudinal Gradient ◽  
Diversity Index ◽  
Dispersal Limitation ◽  
Diversity Indices ◽  
Coniferous Forests ◽  
Qinling Mountains ◽  
Larix Chinensis ◽  
Species Groups ◽  
Adjacent Patch

Forest communities are mosaic systems composed of patches classified into four different developmental patch types: gap patch (G), building patch (B), mature patch (M) and degenerate patch (D). To study the mechanisms maintaining diversity in subalpine coniferous forests, species presence frequency and diversity in the four distinct patch types (G, B, M and D) of Larix chinensis conifer forests at three altitudinal gradients in the Qinling Mountains were analyzed. Our results were as follows: (1) Different species (or functional groups) had distinct presence frequencie s in the four different patch types along the altitudinal gradient. (2) Some species or functional groups (species groups sharing similar traits and response to environment) only occurred in some specific patches. For seed dispersal, species using wind mainly occurred in G and D, while species using small animals mainly occurred in B and M. (3) Species composition of adjacent patch types was more similar than non-adjacent patch types, based on the lower β diversity index of the former. (4) The maximum numbers of species and two diversity indices (D′ and H′) were found in the middle altitudes. Various gap-forming processes and dispersal limitation may be the two major mechanisms determining species diversity in Larix chinensis coniferous forests at the patch scale.

scholarly journals Can mandible morphology help predict feeding habits in Antarctic amphipods?

2020 ◽  
Vol 32 (6) ◽  
pp. 496-507
Author(s):  
Loïc N. Michel ◽  
Fabienne L. Nyssen ◽  
Patrick Dauby ◽  
Marie Verheye
Keyword(s):  
Functional Groups ◽  
Trophic Ecology ◽  
Feeding Habits ◽  
Gut Contents ◽  
Ecological Niches ◽  
Feeding Strategies ◽  
Generalist Predators ◽  
Dietary Specialization ◽  
Important Place ◽  
Antarctic Amphipod

AbstractIn Antarctica, amphipods form a highly diverse group, occupy many different ecological niches and hold an important place in food webs. Here, we aimed to test whether differences in Antarctic amphipod feeding habits were reflected in their mandible morphology, and if mouthpart specialization could be used to describe amphipod trophic ecology. To do so, we compared mandible morphology in nine species spanning seven families and five functional groups (grazers, suspension feeders, generalist predators, specialist predators and scavengers). Mandible morphology adequately depicted some aspects of amphipod trophic ecology, such as the trophic level at which animals feed or their degree of dietary specialization. On the other hand, links between mandible morphology and amphipod diet were seldom unambiguous or straightforward. Similar adaptations were found in distinct functional groups. Conversely, mandible morphology could vary within a single functional group, and phylogenetic effects sometimes complicated the interpretation of form-function relationships. Overall, mandible morphology on its own was generally not sufficient to precisely predict amphipod feeding strategies. However, when combined with other methods (e.g. gut contents, trophic markers), it constitutes a valuable source of information for integrative studies of amphipod ecological diversity in the Southern Ocean.

scholarly journals Native insectary plants support populations of predatory arthropods for Australian vineyards

2019 ◽  
Vol 15 ◽  
pp. 01004 ◽  
Author(s):  
M. Retallack ◽  
L. Thomson ◽  
M. Keller
Keyword(s):  
Biological Control ◽  
Functional Groups ◽  
Native Plants ◽  
South Australia ◽  
Diversity Indices ◽  
Climatic Conditions ◽  
Suitable Habitat ◽  
Wine Grape ◽  
Pest Incidence ◽  
Predatory Arthropods

We provide a summary of two recent studies that investigated the role that three native insectary plants can play in promoting predatory arthropods, and thereby to enhance biological control of vineyard pests in Australia. Native plants are preferred as supplementary flora, as they are locally-adapted to Australia's climatic conditions. Stands of mature Bursaria spinosa, Leptospermum continentale and Rytidosperma ssp. located adjacent to, or in vineyards, in South Australia were sampled for arthropods in 2013/14. Grapevines were also sampled to explore relationships between each plant and associated arthropods using common diversity indices. Twenty seven thousand and ninety-one individual invertebrate specimens were collected, comprising 20 orders and 287 morphospecies. These were categorised into functional groups of predators, herbivores and other. Predatory arthropods dominated the diversity of morphospecies present on each plant. The richness of predator morphospecies across all plant types was nearly double the number found in association with grapevines. It may be possible to increase the functional diversity of predatory arthropods by more than 3x when either B. spinosa or L. continentale is present versus grapevines only, and increase the net number of predator morphospecies by around 27% when Rytidosperma ssp. are planted in combination with grapevines. The selected plants provide a suitable habitat to support diverse and functional populations of predatory arthropods. The opportunity to plant selected native insectary species could help wine grape growers save time and resources by producing fruit with lower pest incidence, while enhancing biodiversity associated with vineyards.

Mercury in Macroinvertebrates from Swedish Forest Lakes: Influence of Lake Type, Habitat, Life Cycle, and Food Quality

1993 ◽  
Vol 50 (3) ◽  
pp. 521-534 ◽  
Author(s):  
Helena Parkman ◽  
Markus Meili
Keyword(s):  
Life Cycle ◽  
Food Quality ◽  
Climatic Factors ◽  
Feeding Habits ◽  
Ecological Factors ◽  
Dry Weight ◽  
Taxonomic Composition ◽  
Sediment Chemistry ◽  
Ecological Niches ◽  
Forest Lakes

Mercury concentrations in lacustrine macroinvertebrates were concurrently studied in eight remote Swedish forest lakes of differing dystrophy, acidity, and eutrophy. The aim was to assess the influence of ecological factors (taxon, habitat, and feeding habits), chemical factors (characterizing different types of lakes), and regional and climatic factors (Hg deposition and mean temperature) on the accumulation of Hg. Concentrations varied from <50 to >5000 ng Hg∙g dry weight−1. A large part of this high variability could be ascribed to differences in water and sediment chemistry, ecological niches, and species-specific seasonalities. Both taxonomic composition and Hg concentrations were highly dependent on the type of lake. Concentrations were highest in acidic dystrophic lakes and lowest in oligotrophic lakes. Mean Hg concentrations in the examined taxa within a lake differed 100-fold. Contrary to widely held views on biomagnification, the lowest concentrations among profundal chironomids were found in predators whereas the highest concentrations occurred in detritivores. Seasonal variations were negligible in some taxa but considerable in others and appeared in some taxa to be related to the life cycle. We conclude that Hg accumulation in macroinvertebrates is largely determined by feeding behaviour and food quality.

scholarly journals Features of forming an invertebrate fauna in technogen environment (Kriviy Rig, Ukraine)

2016 ◽  
pp. 53-56
Author(s):  
Y. Kul'Bachko ◽  
O. Pakhomov ◽  
O. Didur ◽  
I. Loza
Keyword(s):  
Species Richness ◽  
Functional Groups ◽  
Soil Layer ◽  
Taxonomic Composition ◽  
Soil Invertebrates ◽  
Invertebrate Fauna ◽  
Small Thickness ◽  
Industrial Enterprises ◽  
Dominance Structure

The features of invertebrate fauna forming in conditions of technogen pressure (Kriviy Rig, Ukraine) were studied. The taxonomic composition, dominance structure and correlation of soil invertebrates’ functional groups in the large industrial enterprises were examined. It had been found that a small thickness of the soil layer as a habitat for ground animals causes the depletion of taxonomic composition, species richness and decrease the total number of soil invertebrates. Gastropoda molluscs in conditions of technogen pressure are the most adapted to stresses group of invertebrates.

scholarly journals Looking for Ticks from Space: Using Remotely Sensed Spectral Diversity to Assess Amblyomma and Hyalomma Tick Abundance

2019 ◽  
Vol 11 (7) ◽  
pp. 770
Author(s):  
Daniele Da Re ◽  
Eva De Clercq ◽  
Enrico Tordoni ◽  
Maxime Madder ◽  
Raphaël Rousseau ◽  
...  
Keyword(s):  
Land Cover ◽  
Goodness Of Fit ◽  
Landscape Heterogeneity ◽  
Promising Result ◽  
Diversity Indices ◽  
Ecological Niches ◽  
Spectral Variation ◽  
Mosaic Landscape ◽  
Tick Abundance ◽  
Heterogeneous Landscapes

Landscape heterogeneity, as measured by the spectral diversity of satellite imagery, has the potential to provide information on the resources available within the movement capacity range of arthropod vectors, and to help predict vector abundance. The Spectral Variation Hypothesis states that higher spectral diversity is positively related to a higher number of ecological niches present in the landscape, allowing more species to coexist regardless of the taxonomic group considered. Investigating the landscape heterogeneity as a proxy of the resources available to vectors may be relevant for complex and continuous agro-forest mosaics of small farmlands and degraded forests, where land cover classification is often imprecise. In this study, we hypothesized that larger spectral diversity would be associated with higher tick abundance due to the potentially higher number of hosts in heterogeneous landscapes. Specifically, we tested whether spectral diversity indices could represent heterogeneous landscapes, and if so, whether they explain Amblyomma and Hyalomma tick abundance in Benin and inform on their habitat preferences. Benin is a West-African country characterized by a mosaic landscape of farmland and degraded forests. Our results showed that both NDVI-derived and spectral predictors are highly collinear, with NDVI-derived predictors related to vegetated land cover classes and spectral predictors correlated to mosaic landscapes. Amblyomma abundance was not related to the predictors considered. Hyalomma abundance showed positive relationships to spectral diversity indices and negative relationships to NDVI-derived-ones. Though taxa dependent, our approach showed moderate performance in terms of goodness of fit (ca. 13–20% R2), which is a promising result considering the sampling and scale limitations. Spectral diversity indices coupled with classical SRS vegetation indices could be a complementary approach for providing further ecological aspects in the field of disease biogeography.

STRUCTURE OF TRILOBITE COMMUNITIES ALONG A DELTA-MARINE GRADIENT (LOWER ORDOVICIAN; NORTHWESTERN ARGENTINA)

Palaios ◽  
2021 ◽  
Vol 36 (2) ◽  
pp. 39-52
Author(s):  
FERNANDA SERRA ◽  
DIEGO BALSEIRO ◽  
ROMAIN VAUCHER ◽  
BEATRIZ G. WAISFELD
Keyword(s):  
Taxonomic Composition ◽  
Ecological Niches ◽  
Marine Environments ◽  
Key Factors ◽  
Physiological Conditions ◽  
Marine Deposits ◽  
Shelf Slope ◽  
Composition And Structure ◽  
Lower Ordovician ◽  
Nested Structure

ABSTRACTThroughout their long history, trilobites occupied various ecological niches, colonizing a wide variety of marine environments. However, the paleoecology of this group is mostly based on shelf–slope environments and less is known about their distribution in marginal environments. To understand how trilobite communities respond to a deltaic influence, we studied changes in the taxonomic composition and structure of a diverse and well-known Lower Ordovician olenid-dominated fauna from the Argentine Cordillera Oriental along a delta–marine gradient. Cluster analysis revealed two distinct associations, and ordination analysis revealed a clear biotic gradient within each. The ecological structure and diversity trends of both associations follow a predictable response to a depth-related gradient. Impoverished communities with a highly nested structure characterize the lower offshore, whereas rich and even communities occur in the upper offshore. The trend towards higher diversity and greater taxonomic turnover in shallower environments corresponds to greater habitat heterogeneity. Towards the other extreme, only the ubiquitous genus Jujuyaspis was a successful colonizer in deltaic settings. This marked contrast with the more diverse and abundant assemblages of fully marine deposits indicates stressful physiological conditions in marginal-marine environments, where alternating and contrasting normal-marine to brackish-water conditions and high input of siliciclastic material were among the key factors controlling the distribution of these early trilobite communities.

scholarly journals Composition and diversity of Trichoptera (Insecta) larvae communities in the middle section of the Jacuí river and some tributaries, State of Rio Grande do Sul, Brazil

2006 ◽  
Vol 96 (4) ◽  
pp. 389-398 ◽  
Author(s):  
Marcia R. Spies ◽  
Claudio G. Froehlich ◽  
Carla B. Kotzian
Keyword(s):  
Riparian Vegetation ◽  
Rio Grande ◽  
Taxonomic Composition ◽  
Rio Grande Do Sul ◽  
Middle Section ◽  
Low Diversity ◽  
Anthropic Influence ◽  
Study Sites ◽  
Physical Features ◽  
Surber Sampler

The taxonomic composition and diversity of Trichoptera larvae communities were studied in four lotic sites in central region of State of Rio Grande do Sul. Sampling was done monthly from June, 2001 to May, 2002 in four sites located at the middle section of Jacuí River (Point 4) and in three tributaries (Carijinho River - Point 1; Lajeado da Gringa - Point 2 and Lajeado do Gringo - Point 3), with a Surber sampler. The total number of larvae collected was 29,143, belonging to 25 genera distributed in nine families; twenty of these genera are new records for the State. The highest abundance was found at Point 2 (n = 12,547). The highest standardized richness, for a 1,177 specimens sample chosen by chance, was recorded at Point 1, followed by Point 4 (17.7 and 16 genera, respectively). The highest diversity was found at Point 1, and the lowest at Point 3 (H' = 1.31 and H' = 0.77, respectively). Point 1 had the lowest anthropic influence and the best preserved riparian vegetation, while Point 3 presented the highest anthropic impact, and a very reduced riparian vegetation. The diversity of Trichoptera observed in this study is low, compared to the estimated maximum theoretical diversity. Low diversity values are related to the low evenness, since the richness was relatively high. The Trichoptera larvae communities seem to be related to the food availability and physical features (riparian vegetation and anthropic influence) of the study sites.

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