2018
Bouma-Gregson, Keith; Kudela, Raphael M.; Power, Mary
Widespread anatoxin-a detection in benthic cyanobacterial mats throughout a river network Journal Article
In: PLoS One, vol. 13, no. 5, 2018.
Abstract | Links | BibTeX | Tags: algae, biodiversity, ERCZO
@article{Bouma-Gregson2018,
title = {Widespread anatoxin-a detection in benthic cyanobacterial mats throughout a river network},
author = {Keith Bouma-Gregson and Raphael M. Kudela and Mary Power},
doi = {https://doi.org/10.1371/journal.pone.0197669},
year = {2018},
date = {2018-05-18},
journal = {PLoS One},
volume = {13},
number = {5},
abstract = {Benthic algae fuel summer food webs in many sunlit rivers, and are hotspots for primary and
secondary production and biogeochemical cycling. Concerningly, riverine benthic algal
assemblages can become dominated by toxic cyanobacteria, threatening water quality and
public health. In the Eel River in Northern California, over a dozen dog deaths have been
attributed to cyanotoxin poisonings since 2000. During the summers of 2013–2015, we documented
spatial and temporal patterns of cyanotoxin concentrations in the watershed,
showing widespread distribution of anatoxin-a in benthic cyanobacterial mats. Solid phase
adsorption toxin tracking (SPATT) samplers were deployed weekly to record dissolved
microcystin and anatoxin-a levels at 10 sites throughout the watershed, and 187 Anabaenadominated
or Phormidium-dominated cyanobacterial mat samples were collected from 27
locations to measure intracellular anatoxin-a (ATX) and microcystins (MCY). Anatoxin-a levels were higher than microcystin for both SPATT (mean MCY = 0.8 and ATX = 4.8 ng g resin-1 day-1) and cyanobacterial mat samples (mean MCY = 0.074 and ATX = 1.89 μg g-1 DW). Of the benthic mats sampled, 58.9% had detectable anatoxin-a (max = 70.93 μg g-1 DW), while 37.6% had detectable microcystins (max = 2.29 μg g-1 DW). SPATT cyanotoxin
levels peaked in mid-summer in warm mainstem reaches of the watershed. This is one of
the first documentations of widespread anatoxin-a occurrence in benthic cyanobacterial
mats in a North American watershed.},
keywords = {algae, biodiversity, ERCZO},
pubstate = {published},
tppubtype = {article}
}
Benthic algae fuel summer food webs in many sunlit rivers, and are hotspots for primary and
secondary production and biogeochemical cycling. Concerningly, riverine benthic algal
assemblages can become dominated by toxic cyanobacteria, threatening water quality and
public health. In the Eel River in Northern California, over a dozen dog deaths have been
attributed to cyanotoxin poisonings since 2000. During the summers of 2013–2015, we documented
spatial and temporal patterns of cyanotoxin concentrations in the watershed,
showing widespread distribution of anatoxin-a in benthic cyanobacterial mats. Solid phase
adsorption toxin tracking (SPATT) samplers were deployed weekly to record dissolved
microcystin and anatoxin-a levels at 10 sites throughout the watershed, and 187 Anabaenadominated
or Phormidium-dominated cyanobacterial mat samples were collected from 27
locations to measure intracellular anatoxin-a (ATX) and microcystins (MCY). Anatoxin-a levels were higher than microcystin for both SPATT (mean MCY = 0.8 and ATX = 4.8 ng g resin-1 day-1) and cyanobacterial mat samples (mean MCY = 0.074 and ATX = 1.89 μg g-1 DW). Of the benthic mats sampled, 58.9% had detectable anatoxin-a (max = 70.93 μg g-1 DW), while 37.6% had detectable microcystins (max = 2.29 μg g-1 DW). SPATT cyanotoxin
levels peaked in mid-summer in warm mainstem reaches of the watershed. This is one of
the first documentations of widespread anatoxin-a occurrence in benthic cyanobacterial
mats in a North American watershed.
secondary production and biogeochemical cycling. Concerningly, riverine benthic algal
assemblages can become dominated by toxic cyanobacteria, threatening water quality and
public health. In the Eel River in Northern California, over a dozen dog deaths have been
attributed to cyanotoxin poisonings since 2000. During the summers of 2013–2015, we documented
spatial and temporal patterns of cyanotoxin concentrations in the watershed,
showing widespread distribution of anatoxin-a in benthic cyanobacterial mats. Solid phase
adsorption toxin tracking (SPATT) samplers were deployed weekly to record dissolved
microcystin and anatoxin-a levels at 10 sites throughout the watershed, and 187 Anabaenadominated
or Phormidium-dominated cyanobacterial mat samples were collected from 27
locations to measure intracellular anatoxin-a (ATX) and microcystins (MCY). Anatoxin-a levels were higher than microcystin for both SPATT (mean MCY = 0.8 and ATX = 4.8 ng g resin-1 day-1) and cyanobacterial mat samples (mean MCY = 0.074 and ATX = 1.89 μg g-1 DW). Of the benthic mats sampled, 58.9% had detectable anatoxin-a (max = 70.93 μg g-1 DW), while 37.6% had detectable microcystins (max = 2.29 μg g-1 DW). SPATT cyanotoxin
levels peaked in mid-summer in warm mainstem reaches of the watershed. This is one of
the first documentations of widespread anatoxin-a occurrence in benthic cyanobacterial
mats in a North American watershed.
2016
Afkhami, Michelle E.; Strauss, Sharon Y.
Native fungal endophytes suppress an exotic dominant and increase plant diversity over small and large spatial scales Journal Article
In: Ecology, vol. 97, no. 5, pp. 1159–1169, 2016.
Abstract | Links | BibTeX | Tags: biodiversity, Bromus laevipes, Epichloë, evenness, fungal endophyte, grass, hidden players, invasive species, keystone species, mutualism, richness, symbiosis
@article{Afkhami2016,
title = {Native fungal endophytes suppress an exotic dominant and increase plant diversity over small and large spatial scales},
author = {Michelle E. Afkhami and Sharon Y. Strauss},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Afkhami_2016_Eco.pdf},
doi = {10.1890/15-1166.1},
year = {2016},
date = {2016-01-01},
journal = {Ecology},
volume = {97},
number = {5},
pages = {1159–1169},
abstract = {Understanding community dynamics and processes, such as the factors that
generate and maintain biodiversity, drive succession, and affect invasion susceptibility, is
a central goal in ecology and evolution. While most studies of how species interactions
affect communities have focused on highly visible macroorganisms, we show that mutualistic
microfungal endophytes have community-level effects across their host plant’s range and
provide the first example of fungal endophytes enhancing plant diversity. A three-year
field study in which we experimentally manipulated endophyte abundance in a native
Californian grass showed that despite their minute biomass, endophytes dramatically increased
plant community diversity (~110% greater increase with endophytes) by suppressing a
dominant invasive grass, Bromus diandrus. This effect was also detectable, but smaller,
across five additional common gardens spanning ecologically diverse habitats, different
climates, and >400 km of the host grass’ range as well as at microspatial scales within
gardens. Our study illustrates that mutualistic microbes, while often hidden players, can
have unexpectedly large ecological impacts across a wide range of habitats and scales and
may be important for promoting diverse communities and ecosystems.},
keywords = {biodiversity, Bromus laevipes, Epichloë, evenness, fungal endophyte, grass, hidden players, invasive species, keystone species, mutualism, richness, symbiosis},
pubstate = {published},
tppubtype = {article}
}
Understanding community dynamics and processes, such as the factors that
generate and maintain biodiversity, drive succession, and affect invasion susceptibility, is
a central goal in ecology and evolution. While most studies of how species interactions
affect communities have focused on highly visible macroorganisms, we show that mutualistic
microfungal endophytes have community-level effects across their host plant’s range and
provide the first example of fungal endophytes enhancing plant diversity. A three-year
field study in which we experimentally manipulated endophyte abundance in a native
Californian grass showed that despite their minute biomass, endophytes dramatically increased
plant community diversity (~110% greater increase with endophytes) by suppressing a
dominant invasive grass, Bromus diandrus. This effect was also detectable, but smaller,
across five additional common gardens spanning ecologically diverse habitats, different
climates, and >400 km of the host grass’ range as well as at microspatial scales within
gardens. Our study illustrates that mutualistic microbes, while often hidden players, can
have unexpectedly large ecological impacts across a wide range of habitats and scales and
may be important for promoting diverse communities and ecosystems.
generate and maintain biodiversity, drive succession, and affect invasion susceptibility, is
a central goal in ecology and evolution. While most studies of how species interactions
affect communities have focused on highly visible macroorganisms, we show that mutualistic
microfungal endophytes have community-level effects across their host plant’s range and
provide the first example of fungal endophytes enhancing plant diversity. A three-year
field study in which we experimentally manipulated endophyte abundance in a native
Californian grass showed that despite their minute biomass, endophytes dramatically increased
plant community diversity (~110% greater increase with endophytes) by suppressing a
dominant invasive grass, Bromus diandrus. This effect was also detectable, but smaller,
across five additional common gardens spanning ecologically diverse habitats, different
climates, and >400 km of the host grass’ range as well as at microspatial scales within
gardens. Our study illustrates that mutualistic microbes, while often hidden players, can
have unexpectedly large ecological impacts across a wide range of habitats and scales and
may be important for promoting diverse communities and ecosystems.
2001
Levine, Jonathan M.
Local interactions, dispersal, and native and exotic plant diversity along a California stream Journal Article
In: Oikos, vol. 95, no. 3, pp. 397-408, 2001, ISSN: 0030-1299.
Abstract | Links | BibTeX | Tags: biodiversity, community invasibility, ecosystem, invasion resistance, mimulus-guttatus, patterns, populations, regional processes, seed dispersal, species richness
@article{Levine2001,
title = {Local interactions, dispersal, and native and exotic plant diversity along a California stream},
author = {Jonathan M. Levine},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Local-Interactions-Dispersal-and-Native-and-Exotic-Plant-Diversity-along-a-California-Stream_Levine_2001.pdf},
doi = {10.1034/j.1600-0706.2001.950304.x},
issn = {0030-1299},
year = {2001},
date = {2001-12-00},
journal = {Oikos},
volume = {95},
number = {3},
pages = {397-408},
abstract = {Although the species pool, dispersal, and local interactions all influence species diversity, their relative importance is debated. I examined their importance in controlling the number of native and exotic plant species occupying tussocks formed by the sedge Carex nudata along a California stream. Of particular interest were the factors underlying a downstream increase in plant diversity and biological invasions. I conducted seed addition experiments and manipulated local diversity and cover to evaluate the degree to which tussocks saturate with species, and to examine the roles of local competitive processes, abiotic factors, and seed supply in controlling the system-wide patterns.
Seeds of three native and three exotic plants sown onto experimentally assembled tussock communities less successfully established on tussocks with a greater richness of resident plants. Nonetheless, even the most diverse tussocks were somewhat colonized, suggesting that tussocks are not completely saturated with species. Similarly, in an experiment where I sowed seeds onto natural tussocks along the river, colonization increased two- to three-fold when I removed the resident species. Even on intact tussocks, however, seed addition increased diversity, indicating that the tussock assemblages are seed limited. Colonization success on cleared and uncleared tussocks increased downstream from km 0 to km 3 of the study site, but showed no trends from km 3 to km 8. This suggests that while abiotic and biotic features of the tussocks may control the increase in diversity and invasions from km 0 to km 3, similar increases from km 3 to km 8 are more likely explained by potential downstream increases in seed supply. The effective water dispersal of seed mimics and prevailingly downstream winds indicated that dispersal most likely occurs in a downstream direction. These results suggest that resident species diversity, competitive interactions, and seed supply similarly influence the colonization of native and exotic species.},
keywords = {biodiversity, community invasibility, ecosystem, invasion resistance, mimulus-guttatus, patterns, populations, regional processes, seed dispersal, species richness},
pubstate = {published},
tppubtype = {article}
}
Although the species pool, dispersal, and local interactions all influence species diversity, their relative importance is debated. I examined their importance in controlling the number of native and exotic plant species occupying tussocks formed by the sedge Carex nudata along a California stream. Of particular interest were the factors underlying a downstream increase in plant diversity and biological invasions. I conducted seed addition experiments and manipulated local diversity and cover to evaluate the degree to which tussocks saturate with species, and to examine the roles of local competitive processes, abiotic factors, and seed supply in controlling the system-wide patterns.
Seeds of three native and three exotic plants sown onto experimentally assembled tussock communities less successfully established on tussocks with a greater richness of resident plants. Nonetheless, even the most diverse tussocks were somewhat colonized, suggesting that tussocks are not completely saturated with species. Similarly, in an experiment where I sowed seeds onto natural tussocks along the river, colonization increased two- to three-fold when I removed the resident species. Even on intact tussocks, however, seed addition increased diversity, indicating that the tussock assemblages are seed limited. Colonization success on cleared and uncleared tussocks increased downstream from km 0 to km 3 of the study site, but showed no trends from km 3 to km 8. This suggests that while abiotic and biotic features of the tussocks may control the increase in diversity and invasions from km 0 to km 3, similar increases from km 3 to km 8 are more likely explained by potential downstream increases in seed supply. The effective water dispersal of seed mimics and prevailingly downstream winds indicated that dispersal most likely occurs in a downstream direction. These results suggest that resident species diversity, competitive interactions, and seed supply similarly influence the colonization of native and exotic species.
Seeds of three native and three exotic plants sown onto experimentally assembled tussock communities less successfully established on tussocks with a greater richness of resident plants. Nonetheless, even the most diverse tussocks were somewhat colonized, suggesting that tussocks are not completely saturated with species. Similarly, in an experiment where I sowed seeds onto natural tussocks along the river, colonization increased two- to three-fold when I removed the resident species. Even on intact tussocks, however, seed addition increased diversity, indicating that the tussock assemblages are seed limited. Colonization success on cleared and uncleared tussocks increased downstream from km 0 to km 3 of the study site, but showed no trends from km 3 to km 8. This suggests that while abiotic and biotic features of the tussocks may control the increase in diversity and invasions from km 0 to km 3, similar increases from km 3 to km 8 are more likely explained by potential downstream increases in seed supply. The effective water dispersal of seed mimics and prevailingly downstream winds indicated that dispersal most likely occurs in a downstream direction. These results suggest that resident species diversity, competitive interactions, and seed supply similarly influence the colonization of native and exotic species.
2000
Levine, Jonathan M.
Species diversity and biological invasions: relating local process to community pattern Journal Article
In: Science, vol. 288, no. 5467, pp. 852-854, 2000, ISSN: 0036-8075.
Abstract | Links | BibTeX | Tags: biodiversity, ecosystem, grasslands, invasibility, resistance, stability
@article{Levine2000b,
title = {Species diversity and biological invasions: relating local process to community pattern},
author = {Jonathan M. Levine},
url = {https://angelo.berkeley.edu/wp-content/uploads/sites/59/Science-2000-Levine-852-4.pdf},
issn = {0036-8075},
year = {2000},
date = {2000-05-05},
journal = {Science},
volume = {288},
number = {5467},
pages = {852-854},
abstract = {In a California riparian system, the most diverse natural assemblages are the most invaded by exotic plants. A direct in situ manipulation of local diversity and a seed addition experiment showed that these patterns emerge despite the intrinsic negative effects of diversity on invasions. The results suggest that species loss at small scales may reduce invasion resistance. At community-wide scales, the overwhelming effects of ecological factors spatially covarying with diversity, such as propagule supply, make the most diverse communities most likely to be invaded.},
keywords = {biodiversity, ecosystem, grasslands, invasibility, resistance, stability},
pubstate = {published},
tppubtype = {article}
}
In a California riparian system, the most diverse natural assemblages are the most invaded by exotic plants. A direct in situ manipulation of local diversity and a seed addition experiment showed that these patterns emerge despite the intrinsic negative effects of diversity on invasions. The results suggest that species loss at small scales may reduce invasion resistance. At community-wide scales, the overwhelming effects of ecological factors spatially covarying with diversity, such as propagule supply, make the most diverse communities most likely to be invaded.
1999
Levine, Jonathan M.; D’Antonio, Carla M.
Elton revisited: a review of evidence linking diversity and invasibility Journal Article
In: Oikos, vol. 87, no. 1, pp. 15-26, 1999, ISSN: 0030-1299, (File size exceeds maximum allowable for Angelo’s website. Please see the attached stable link for PDF.).
Abstract | Links | BibTeX | Tags: biodiversity, biological invasions, California, COMMUNITIES, competition, exotic plants, grassland, introduced Hawaiian avifauna, New Zealand, positive interactions, riparian zones
@article{Levine1999,
title = {Elton revisited: a review of evidence linking diversity and invasibility},
author = {Jonathan M. Levine and Carla M. D'Antonio},
url = {http://www.jstor.org/stable/3546992},
doi = {10.2307/3546992},
issn = {0030-1299},
year = {1999},
date = {1999-10-00},
journal = {Oikos},
volume = {87},
number = {1},
pages = {15-26},
abstract = {It is commonly believed that diverse communities better resist invasion by exotic species than do simple communities. We examined the history of this notion, and evaluated theoretical and empirical work linking diversity and invasions. We found that much of the historical work that has contributed to the perception that diverse communities are less invasible, including Elton's observations and MacArthur's species-packing and diversity-stability models, is based on controversial premises. Nevertheless, more recent theoretical studies consistently supported the predicted negative relationship between diversity and invasibility. The results of empirical studies, however, were decidedly mixed. Constructed community studies directly manipulating diversity found both positive and negative effects of diversity on invasibility in both field and microcosm settings. Other empirical studies tracking the assembly of ecological communities generally suggested that communities decline in invasibility as species accumulate over time, though the role of diversity itself was often ambiguous. Studies of the spatial correlation between diversity and invasion and studies experimentally adding invaders to natural systems indicated that diverse communities tend to be more invasible. We argue that these results most likely reflect environmental factors spatially covarying with diversity in natural communities (e.g. resources, disturbance), and not the effects of diversity itself as uncovered by constructed community studies. Nevertheless, the consistent positive relationship between exotic species abundance and resident species diversity found in spatial pattern studies suggests that invaders and resident species are more similar than often believed, and the implications of this for theories of invasion are discussed.},
note = {File size exceeds maximum allowable for Angelo's website. Please see the attached stable link for PDF.},
keywords = {biodiversity, biological invasions, California, COMMUNITIES, competition, exotic plants, grassland, introduced Hawaiian avifauna, New Zealand, positive interactions, riparian zones},
pubstate = {published},
tppubtype = {article}
}
It is commonly believed that diverse communities better resist invasion by exotic species than do simple communities. We examined the history of this notion, and evaluated theoretical and empirical work linking diversity and invasions. We found that much of the historical work that has contributed to the perception that diverse communities are less invasible, including Elton’s observations and MacArthur’s species-packing and diversity-stability models, is based on controversial premises. Nevertheless, more recent theoretical studies consistently supported the predicted negative relationship between diversity and invasibility. The results of empirical studies, however, were decidedly mixed. Constructed community studies directly manipulating diversity found both positive and negative effects of diversity on invasibility in both field and microcosm settings. Other empirical studies tracking the assembly of ecological communities generally suggested that communities decline in invasibility as species accumulate over time, though the role of diversity itself was often ambiguous. Studies of the spatial correlation between diversity and invasion and studies experimentally adding invaders to natural systems indicated that diverse communities tend to be more invasible. We argue that these results most likely reflect environmental factors spatially covarying with diversity in natural communities (e.g. resources, disturbance), and not the effects of diversity itself as uncovered by constructed community studies. Nevertheless, the consistent positive relationship between exotic species abundance and resident species diversity found in spatial pattern studies suggests that invaders and resident species are more similar than often believed, and the implications of this for theories of invasion are discussed.
1996
Carpenter, Stephen; Frost, T.; Persson, Lennart; Power, Mary E.; Soto, D.
Freshwater ecosystems: Linkages of complexity and processes Book Chapter
In: Mooney, O. E. Sala J. H. Cushman H. A.; Schulze, E. D. (Ed.): vol. Functional Roles of Biodiversity: A Glob, Chapter 12, pp. 299-325, John Wiley & Sons Ltd, 1996, (The file size (6 MB) exceeds Angelo’s maximum (2 MB). Please see the stable link attached for PDF.).
Links | BibTeX | Tags: biodiversity, freshwater ecosystem
@inbook{Carpenter1996,
title = {Freshwater ecosystems: Linkages of complexity and processes},
author = {Stephen Carpenter and T. Frost and Lennart Persson and Mary E. Power and D. Soto},
editor = {O. E. Sala J.H. Cushman H.A. Mooney and E. D. Schulze},
url = {http://www.scopenvironment.org/downloadpubs/scope55/scope55-ch12.pdf},
year = {1996},
date = {1996-00-00},
journal = {Functional Roles of Biodiversity: A Global Perspective},
volume = {Functional Roles of Biodiversity: A Glob},
pages = {299-325},
publisher = {John Wiley & Sons Ltd},
chapter = {12},
note = {The file size (6 MB) exceeds Angelo's maximum (2 MB). Please see the stable link attached for PDF.},
keywords = {biodiversity, freshwater ecosystem},
pubstate = {published},
tppubtype = {inbook}
}