Influence of abiotic and biotic factors on two co-occurring species of Bolboschoenus

2000 ◽  
Vol 51 (1) ◽  
pp. 73 ◽  
Author(s):  
Mark A. Siebentritt ◽  
George G. Ganf
Keyword(s):  
Water Depth ◽  
Abiotic Factors ◽  
Elevation Gradient ◽  
Biotic Interactions ◽  
Biotic Factors ◽  
Depth Gradient ◽  
Shoot Height ◽  
Relative Growth ◽  
Net Assimilation ◽  
Abiotic And Biotic Factors

Distribution of the emergent macrophytes Bolboschoenus medianus and Bolboschoenus caldwellii is dominated by the latter at regions higher on the elevation gradient, whereas the former is dominant further down the gradient. Monocultures and mixtures of plants were grown across a water-depth gradient in experimental ponds to determine whether distribution is due to abiotic factors, biotic factors, or a combination of both. Monocultures of each species tolerated exposure, showing little variation in relative growth rate (RGR), net assimilation rate (NAR) or leaf area ratio (LAR). Survival when initially flooded was dependent on shoot height. Plants surviving inundation responded by increasing height through reallocation of biomass. The RGR of B. medianus was maintained across the water-depth gradient by increasing NAR as LAR declined. The RGR of B. caldwellii beyond a depth of −20 cm declined because reductions in LAR were not paralleled by increases in NAR. Mixtures of species growing at 20 cm and 0 cm indicated that biotic interactions occurred and that B. caldwellii was the dominant species. Neither species dominated at −60 cm, presumably because this was beyond the depth tolerated by both species. The study suggests that the zonation of B. medianus and B. caldwellii is attributable to a combination of both abiotic and biotic factors.

scholarly journals Environmental factors influencing fine-scale distribution of Antarctica’s only endemic insect

Oecologia ◽  
2020 ◽  
Vol 194 (4) ◽  
pp. 529-539
Author(s):  
Leslie J. Potts ◽  
J. D. Gantz ◽  
Yuta Kawarasaki ◽  
Benjamin N. Philip ◽  
David J. Gonthier ◽  
...  
Keyword(s):  
Antarctic Peninsula ◽  
Spatial Scales ◽  
Abiotic Factors ◽  
Ecological Factors ◽  
Biotic Interactions ◽  
Species Distributions ◽  
Biotic Factors ◽  
Belgica Antarctica ◽  
Abiotic And Biotic Factors ◽  
The Antarctic

AbstractSpecies distributions are dependent on interactions with abiotic and biotic factors in the environment. Abiotic factors like temperature, moisture, and soil nutrients, along with biotic interactions within and between species, can all have strong influences on spatial distributions of plants and animals. Terrestrial Antarctic habitats are relatively simple and thus good systems to study ecological factors that drive species distributions and abundance. However, these environments are also sensitive to perturbation, and thus understanding the ecological drivers of species distribution is critical for predicting responses to environmental change. The Antarctic midge, Belgica antarctica, is the only endemic insect on the continent and has a patchy distribution along the Antarctic Peninsula. While its life history and physiology are well studied, factors that underlie variation in population density within its range are unknown. Previous work on Antarctic microfauna indicates that distribution over broad scales is primarily regulated by soil moisture, nitrogen content, and the presence of suitable plant life, but whether these patterns are true over smaller spatial scales has not been investigated. Here we sampled midges across five islands on the Antarctic Peninsula and tested a series of hypotheses to determine the relative influences of abiotic and biotic factors on midge abundance. While historical literature suggests that Antarctic organisms are limited by the abiotic environment, our best-supported hypothesis indicated that abundance is predicted by a combination of abiotic and biotic conditions. Our results are consistent with a growing body of literature that biotic interactions are more important in Antarctic ecosystems than historically appreciated.

An introduction to the 'micronet' of cyanobacterial harmful algal blooms (CyanoHABs): cyanobacteria, zooplankton and microorganisms: a review

2020 ◽  
Vol 71 (5) ◽  
pp. 636 ◽  
Author(s):  
Elżbieta Wilk-Woźniak
Keyword(s):  
Harmful Algal Blooms ◽  
Algal Blooms ◽  
Abiotic Factors ◽  
Biotic Interactions ◽  
Cyanobacterial Blooms ◽  
Biotic Factors ◽  
New Findings ◽  
Change Temperature ◽  
Abiotic And Biotic Factors ◽  
Cyanobacterial Harmful Algal Blooms

Cyanobacterial harmful algal blooms are known all around the world. Climate change (temperature increase) and human activity (eutrophication) are factors that promote the proliferation of cyanobacteria, leading to the development of blooms and the release of toxins. Abiotic and biotic factors are responsible for the development of blooms and how long they last. Although the abiotic factors controlling blooms are well known, knowledge of biotic factors and their interactions is still lacking. This paper reviews five levels of biotic interactions, namely cyanobacteria–zooplankton, cyanobacteria–ciliates, cyanobacteria–bacteria, cyanobacteria–viruses and cyanobacteria–fungi, showing a more complex food web network than was previously thought. New findings published recently, such as the relationships between cyanobacteria and viruses or cyanobacteria and fungi, indicate that cyanobacterial blooms are not the end of the cycle of events taking place in water habitats, but rather the middle of them. As such, a new approach needs to consider mutual connections, genetic response, horizontal gene transfer and non-linear flow of carbon.

scholarly journals Biogeomorphic feedbacks and the ecosystem engineering of recently deglaciated terrain

2018 ◽  
Vol 43 (1) ◽  
pp. 24-45 ◽  
Author(s):  
Hannah R Miller ◽  
Stuart N Lane
Keyword(s):  
Environmental Stress ◽  
Ecosystem Engineer ◽  
Abiotic Factors ◽  
Ecosystem Engineering ◽  
Soil Development ◽  
Water Dynamics ◽  
Biotic Factors ◽  
Successional Stage ◽  
Abiotic And Biotic Factors

Matthews’ 1992 geoecological model of vegetation succession within glacial forefields describes how following deglaciation the landscape evolves over time as the result of both biotic and abiotic factors, with the importance of each depending on the level of environmental stress within the system. We focus in this paper on how new understandings of abiotic factors and the potential for biogeomorphic feedbacks between abiotic and biotic factors makes further development of this model important. Disturbance and water dynamics are two abiotic factors that have been shown to create stress gradients that can drive early ecosystem succession. The subsequent establishment of microbial communities and vegetation can then result in biogeomorphic feedbacks via ecosystem engineering that influence the role of disturbance and water dynamics within the system. Microbes can act as ecosystem engineers by supplying nutrients (via remineralization of organic matter and nitrogen fixation), enhancing soil development, either decreasing (encouraging weathering) or increasing (binding sediment grains) geomorphic stability, and helping retain soil moisture. Vegetation can act as an ecosystem engineer by fixing nitrogen, enhancing soil development, modifying microbial community structure, creating seed banks, and increasing geomorphic stability. The feedbacks between vegetation and water dynamics in glacial forefields are still poorly studied. We propose a synthesized model of ecosystem succession within glacial forefields that combines Matthews’ initial geoecological model and Corenblit's model to illustrate how gradients in environmental stress combined with successional time drive the balance between abiotic and biotic factors and ultimately determine the successional stage and potential for biogeomorphic feedbacks.

Water-depth tolerances of the dominant emergent macrophytes of the Delta Marsh, Manitoba

1992 ◽  
Vol 70 (9) ◽  
pp. 1860-1867 ◽  
Author(s):  
Louisa Squires ◽  
A. G. Van der Valk
Keyword(s):  
Water Depth ◽  
Shoot Density ◽  
Shoot Length ◽  
Depth Gradient ◽  
Shoot Height ◽  
Delta Marsh ◽  
Below Ground ◽  
Seasonally Flooded ◽  
Water Depths

The growth (shoot height, cumulative shoot length, shoot density, above- and below-ground biomass) of seven emergent species growing at five different water depths was measured for 2 years. These species belonged to three different ecological classes: (i) upper marsh species (Carex atherodes, Scolochloa festucacea, and Phragmites australis) that occupy sections of the water-depth gradient that are only seasonally flooded in the Delta Marsh; (ii) lower marsh species (Typha glauca and Scirpus lacutris spp. glaucus) that occupy permanently flooded areas; and (iii) drawdown species (Scirpus lacustris spp. validus and Scirpus maritimus) that become established temporarily during drawdowns. Upper marsh species could not adjust their shoot length if they were growing in water deeper than 20 cm. Lower marsh species were able to do this in water up to 70 cm deep. All three types survived for 1 or 2 years in water too deep for long-term persistence. Scirpus species survived as tubers in areas with water too deep for them to grow. The distributions of the seven species in the experiments overlapped considerably, and all species cooccurred at water depths to 70 cm after 2 years of flooding. The predicted distribution in the four dominant species along a water-depth gradient were consistent with their actual distributions in the Delta Marsh, but their predicted distributions overlapped much more than is the case in the field. Key words: emergent vegetation, experiment, water-depth tolerance, plant growth, distributions.

scholarly journals Commensal associations and benthic habitats shape macroevolution of the bivalve clade Galeommatoidea

2016 ◽  
Vol 283 (1834) ◽  
pp. 20161006 ◽  
Author(s):  
Jingchun Li ◽  
Diarmaid Ó Foighil ◽  
Ellen E. Strong
Keyword(s):  
Niche Partitioning ◽  
Ecological Factors ◽  
Biotic Interactions ◽  
Marine Biodiversity ◽  
Biotic Factors ◽  
Free Living ◽  
Symbiotic Associations ◽  
Large Numbers ◽  
Living Species ◽  
Abiotic And Biotic Factors

The great diversity of marine life has been shaped by the interplay between abiotic and biotic factors. Among different biotic interactions, symbiosis is an important yet less studied phenomenon. Here, we tested how symbiotic associations affected marine diversification, using the bivalve superfamily Galeommatoidea as a study system. This superfamily contains large numbers of obligate commensal as well as free-living species and is therefore amenable to comparative approaches. We constructed a global molecular phylogeny of Galeommatoidea and compared macroevolutionary patterns between free-living and commensal lineages. Our analyses inferred that commensalism/sediment-dwelling is likely to be the ancestral condition of Galeommatoidea and that secondary invasions of hard-bottom habitats linked to the loss of commensalism. One major clade containing most of the free-living species exhibits a 2–4 times higher diversification rate than that of the commensals, likely driven by frequent niche partitioning in highly heterogeneous hard-bottom habitats. However, commensal clades show much higher within-clade morphological disparity, likely promoted by their intimate associations with diverse hosts. Our study highlights the importance of interactions between different ecological factors in shaping marine macroevolution and that biotic factors cannot be ignored if we wish to fully understand processes that generate marine biodiversity.

scholarly journals Trophic cascades and connectivity in coastal benthic marine ecosystems: a meta-analysis of experimental and observational research

2020 ◽  
Author(s):  
Aaron Matthius Eger ◽  
Julia Kathleen Baum
Keyword(s):  
Abiotic Factors ◽  
Meta Analysis ◽  
Trophic Cascades ◽  
Marine Ecosystems ◽  
Trophic Levels ◽  
Observational Research ◽  
Biotic Factors ◽  
Population Response ◽  
High Nutrient ◽  
Abiotic And Biotic Factors

Predators often exert top-down control on lower trophic levels, such that their removal or addition can trigger trophic cascades. Despite coastal ecosystems containing well known trophic cascades, the abiotic and biotic factors governing the occurrence and strength of these cascades are still unclear. We worked to explain the variability of trophic cascades in benthic marine ecosystems by conducting a meta-analysis of experimental (N = 17) and observational (N = 22) studies that recorded herbivore and producer populations in the presence and absence of a first level predator. From these data (147 predator-herbivore-producer measurements), we show that, although not as strong as previously estimated, the presence of predators decreased herbivore populations between 2.1 to 4.76 times and increased producer populations by 1.62 to 2.83 times. Biotic factors related to species’ body size were most influential in determining herbivore population response to predator presence, while abiotic factors, including nutrient concentration, best determined the producer population response. Our results also show producers responded more intensely to changes in herbivore populations in high nutrient and low temperature environments. Looking at populations in marine reserves we found that herbivore populations in reserves were 3.00 times lower on average, compared to areas outside the reserve, while producer populations were on average 1.84 times higher. Overall, this work advances our understanding of the factors modulating trophic cascade strength, demonstrates that reserves can have ecosystem wide impacts, and establishes a new baseline of trophic cascades in benthic marine systems.

scholarly journals The Evaluation of Grazed Grasslands on the Hortobágy

2003 ◽  
pp. 50-54
Author(s):  
Csilla Tóth ◽  
Géza Nagy ◽  
Antónia Nyakas
Keyword(s):  
Abiotic Factors ◽  
Ground Cover ◽  
The Other ◽  
Biotic Factors ◽  
Rumex Crispus ◽  
Dry Grassland ◽  
Carduus Acanthoides ◽  
Plant Groups ◽  
Natural Grasslands ◽  
Abiotic And Biotic Factors

The sward composition of different grasslands on Puszta Hortobágy has been developed according to prevailing abiotic and biotic factors. The abiotic conditions have been more or less constans for long periods of time, and the abiotic factors are determined by ecological conditions (climate, soil, topography). Among biotic factors grazing of herbivores was important in the development of Hortobágy grasslands for centuries (Sipos and Varga, 1993). Result of three-year investigations on the sward composition of grasslands utilised in different ways are presented. Data on ground cover, number of plant species, representation of different plant groups (grasses, sedge and bent-grass, herbs, legumes) and weeds are reported from six different grazed grassland types from Puszta Hortobágy.In 1999-2001 a sward composition survey was conducted. Sample areas of 2x2 m2 were marked out in three replicates: on temporarily waterlogged grassland grazed by cattle (A), on dry grassland grazed by cattle (B), on dry grassland grazed by sheep (C), on dry grassland grazed by buffaloes (D), on dry grassland grazed by buffaloes and geese (E), on dry grassland cut for hay in May then grazed by geese (F). On the sample areas sward composition of grasslands was estimated according to Balázs (1949).The average ground cover of different grasslands ranged between 60 and 100% (Table 2). The lowest value was found for grasslands C and E, which are grazed by sheep (C) and buffaloes and geese alternately (E). In these grasslands were some open spaces, on the other grasslands completely closed swards covers were observed.The species diversity of these natural grasslands are high (Table 2). The grassland F, which were cut for hay in May had the lowest diversity (17-21). The highest number of species was found on grassland A and B (32-51), on other grazed grasslands (C, D, E) had 29-48 species.The different plant groups had different representation in the total ground cover (Table 3). The number of herbs was always higher then that of grasses, but the cover of herbs was lower then that of grasses. The legumes and the sedge and bent grasses were present in high abundance in grassland A, but in the other grasslands were not.The composition of herbs should be a warning for future utilisation systems on some grasslands of Hortobágy. Some species of herbs, e.g. Achillea millefolium, Artemisia vulgaris, Carduus acanthoides, Cirsium arvense, Cirsium vulgare Eryngium campestre, Galium mollugo, Galium verum, Ononis spinosa, Rumex crispus, Verbascum phlomoideus, Phragmites australis can be invasive on short grasslands.

scholarly journals Trophic cascades and connectivity in coastal benthic marine ecosystems: a meta-analysis of experimental and observational research

2020 ◽  
Vol 656 ◽  
pp. 139-152 ◽  
Author(s):  
AM Eger ◽  
JK Baum
Keyword(s):  
Abiotic Factors ◽  
Meta Analysis ◽  
Trophic Cascades ◽  
Past Research ◽  
Marine Ecosystems ◽  
Trophic Levels ◽  
Observational Research ◽  
Biotic Factors ◽  
Population Responses ◽  
Abiotic And Biotic Factors

Predators can exert top-down control on lower trophic levels, such that their removal or addition may trigger trophic cascades. Despite coastal ecosystems containing well known trophic cascades, there remains uncertainty about the abiotic and biotic factors governing the occurrence and strength of these cascades. Here, we sought to explain the variability of trophic cascades in benthic marine ecosystems by conducting a meta-analysis of experimental (n = 17) and observational (n = 22) studies that recorded herbivore and producer populations in the presence and absence of a predator. From these data (147 predator-herbivore-producer measurements), we show that predators decreased herbivore populations between 2.1-4.76 times and increased producer populations by 1.62-2.83 times their original biomass, abundance, or density. Contrary to past research, these values are comparable to other ecosystems. Biotic factors related to species body size were most influential in determining herbivore population responses to the presence of predators, while abiotic factors, including nutrient concentration, best determined producer population responses. Our results also show that producers responded more strongly to changes in herbivore populations in high-nutrient and low-temperature environments. We found that herbivore populations in marine reserves were 2.83 times lower on average compared to areas outside the reserve, while producer populations were on average 1.90 times higher. Overall, this work advances understanding of factors modulating trophic cascade strength, demonstrates that reserves can have ecosystem-wide impacts, and provides new information about the average strength of trophic cascades in benthic marine ecosystems.

scholarly journals Reorganization of surviving mammal communities after the end-Pleistocene megafaunal extinction

Science ◽  
2019 ◽  
Vol 365 (6459) ◽  
pp. 1305-1308 ◽  
Author(s):  
Anikó B. Tóth ◽  
S. Kathleen Lyons ◽  
W. Andrew Barr ◽  
Anna K. Behrensmeyer ◽  
Jessica L. Blois ◽  
...  
Keyword(s):  
Community Assembly ◽  
Abiotic Factors ◽  
Biotic Interactions ◽  
Niche Overlap ◽  
Biotic Factors ◽  
Large Mammals ◽  
Continental Scale ◽  
Species Pairs ◽  
Mammal Communities ◽  
Over Time

Large mammals are at high risk of extinction globally. To understand the consequences of their demise for community assembly, we tracked community structure through the end-Pleistocene megafaunal extinction in North America. We decomposed the effects of biotic and abiotic factors by analyzing co-occurrence within the mutual ranges of species pairs. Although shifting climate drove an increase in niche overlap, co-occurrence decreased, signaling shifts in biotic interactions. Furthermore, the effect of abiotic factors on co-occurrence remained constant over time while the effect of biotic factors decreased. Biotic factors apparently played a key role in continental-scale community assembly before the extinctions. Specifically, large mammals likely promoted co-occurrence in the Pleistocene, and their loss contributed to the modern assembly pattern in which co-occurrence frequently falls below random expectations.

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