scholarly journals Facilitation by macroalgae [full paper published in Algae 32 (1): 41-46, 2017]

2017 ◽  
Author(s):  
Ricardo Augusto Scrosati
Keyword(s):  
Benthic Communities ◽  
Algal Species ◽  
High Stress ◽  
Canopy Cover ◽  
Community Level ◽  
Rocky Intertidal ◽  
Marine System ◽  
Sources Of Variation ◽  
Intertidal Habitats ◽  
High Elevations

In rocky intertidal habitats, abiotic stress due to desiccation and thermal extremes increases with elevation because of tides. A study in Atlantic Canada showed that, at low elevations where conditions are benign due to the brief low tides, fucoid algal canopies (Ascophyllum nodosum and Fucus spp.) do not affect the structure of benthic communities. However, at middle and high elevations, where low tides last longer, fucoid canopies limit abiotic extremes and increase the richness (number of invertebrate and algal species, except fucoids) of benthic communities. Using the data from that study, this paper compares the intensity of facilitation and its importance (relative to all other sources of variation in richness) between middle and high elevations, which represent intermediate and high stress, respectively. Facilitation intensity was calculated as the percent increase in benthic richness between quadrats with low and high canopy cover, while the importance of facilitation was calculated as the percentage of variation in richness explained by canopy cover. Data for 689 quadrats spanning 350 km of coastline were used. Both the intensity and importance of facilitation were greater at middle elevations than at high elevations. As canopies do not affect benthic communities at low elevations, this study suggests that the facilitation-stress relationship at the community level is unimodal for this marine system. Such a pattern was found for some terrestrial systems dominated by canopy-forming plants. Thus, it might be ubiquitous in nature and, as further studies refine it, it might help to predict community-level facilitation depending on environmental stress.

scholarly journals Community-level facilitation by macroalgal foundation species peaks at an intermediate level of environmental stress

2016 ◽  
Author(s):  
Ricardo A. Scrosati
Keyword(s):  
Environmental Stress ◽  
Benthic Communities ◽  
Atlantic Coast ◽  
High Stress ◽  
Canopy Cover ◽  
Foundation Species ◽  
Community Level ◽  
Rocky Intertidal ◽  
Published Data ◽  
High Elevations

AbstractThis paper examines how community-level facilitation by macroalgal foundation species changes with environmental stress. In rocky intertidal habitats, abiotic stress (mainly due to desiccation and thermal extremes during low tides) increases sharply with elevation because of tide dynamics. A previous study done on the Atlantic coast of Nova Scotia (Canada) showed that, at low elevations, where conditions are benign because low tides are brief, fucoid algal canopies (Ascophyllum nodosum and Fucus spp.) do not affect the structure of benthic communities. However, at middle and high elevations, where low tides last longer, fucoid canopies limit abiotic extremes near the substrate and, in that way, increase the richness of benthic communities. Richness was measured as the number of benthic algal (except fucoids) and invertebrate species found in replicate quadrats. Using the published data from that study, the present study compares the intensity of facilitation and its importance (relative to all other sources of variation in richness) between middle and high elevations, which represent intermediate and high stress, respectively. Facilitation intensity was calculated as the percent increase in benthic richness between quadrats with low canopy cover and quadrats with high canopy cover, while the importance of facilitation was calculated as the percentage of observed variation in richness that was explained by canopy cover. Data for a total of 688 quadrats surveyed along 350 km of coastline were used. The analyses revealed that both the intensity and importance of facilitation were greater at middle elevations than at high elevations. As canopies were previously found not to affect benthic communities at low elevations, this study indicates that the facilitation–stress relationship viewed at the community level is unimodal for this marine system. Such a trend was already found for some terrestrial systems involving canopy-forming plants as foundation species. Thus, this unimodal pattern may be ubiquitous in nature and, as further studies refine it, might help to predict community-level facilitation depending on environmental stress.

scholarly journals Barnacle recruit density and size increase from high to middle intertidal elevations in wave-exposed habitats on the Atlantic coast of Nova Scotia

2019 ◽  
Author(s):  
Ricardo A Scrosati
Keyword(s):  
Nova Scotia ◽  
Interspecific Interactions ◽  
Atlantic Coast ◽  
Rocky Intertidal ◽  
Ne Atlantic ◽  
Relevant Role ◽  
Ne Pacific ◽  
Intertidal Habitats ◽  
High Elevations ◽  
Intertidal Environments

Barnacle recruitment is often studied in rocky intertidal habitats due to the relevant role that barnacles can play in intertidal communities. In 2014, barnacle (Semibalanus balanoides) recruitment was measured at high elevations in wave-exposed intertidal habitats on the NW Atlantic coast in Nova Scotia, Canada. Values were considerably lower than previously reported for middle elevations in wave-exposed intertidal habitats on the NE Atlantic and NE Pacific coasts. To determine if such differences in recruitment may have resulted from elevation influences, I did a field experiment in 2019 in wave-exposed intertidal habitats in Nova Scotia to test the hypothesis that recruitment is higher at middle than at high elevations, based on known environmental differences between both elevation zones. Based on data from three locations spanning 158 km of the Nova Scotia coast, barnacle recruitment was, on average, nearly 200 % higher (and recruits were larger) at middle than at high elevations. However, even with this increase, barnacle recruitment on this NW Atlantic coast is still lower than for comparable habitats on the NE Atlantic and NE Pacific coasts, and also lower than previously reported for wave-exposed locations farther south on the NW Atlantic coast, in Maine, USA. Therefore, barnacle recruitment in wave-exposed intertidal environments in Nova Scotia appears to be only moderate relative to other shores. This difference in the supply of barnacle recruits might influence the intensity of interspecific interactions involving barnacles.

scholarly journals Changes in barnacle recruitment and recruit body size with intertidal elevation on wave-exposed rocky shores in Nova Scotia

2019 ◽  
Author(s):  
Ricardo A. Scrosati
Keyword(s):  
Nova Scotia ◽  
Interspecific Interactions ◽  
Atlantic Coast ◽  
Rocky Intertidal ◽  
Rocky Shores ◽  
Ne Atlantic ◽  
Relevant Role ◽  
Ne Pacific ◽  
Intertidal Habitats ◽  
High Elevations

AbstractBarnacle recruitment is often studied in rocky intertidal habitats due to the relevant role that barnacles can play in intertidal communities. In 2014, barnacle (Semibalanus balanoides) recruitment was measured at high elevations in wave-exposed intertidal habitats on the NW Atlantic coast in Nova Scotia, Canada. Values were considerably lower than previously reported for middle elevations in wave-exposed intertidal habitats on the NE Atlantic and NE Pacific coasts. To determine if such differences in recruitment may have resulted from elevation influences, I did a field experiment in 2019 in wave-exposed intertidal habitats in Nova Scotia to test the hypothesis that recruitment is higher at middle than at high elevations, based on known environmental differences between both elevation zones. Based on data from three locations spanning 158 km of the Nova Scotia coast, barnacle recruitment was, on average, nearly 200 % higher (and recruits were larger) at middle than at high elevations. However, even with this increase, barnacle recruitment on this NW Atlantic coast is still lower than for comparable habitats on the NE Atlantic and NE Pacific coasts, and also lower than previously reported for wave-exposed locations farther south on the NW Atlantic coast, in Maine, USA. Therefore, barnacle recruitment in wave-exposed intertidal environments in Nova Scotia appears to be only moderate relative to other shores. This difference in the supply of barnacle recruits might influence the intensity of interspecific interactions involving barnacles.

scholarly journals Barnacle recruit density and size increase from high to middle intertidal elevations in wave-exposed habitats on the Atlantic coast of Nova Scotia

2019 ◽  
Author(s):  
Ricardo A Scrosati
Keyword(s):  
Nova Scotia ◽  
Interspecific Interactions ◽  
Atlantic Coast ◽  
Rocky Intertidal ◽  
Ne Atlantic ◽  
Relevant Role ◽  
Ne Pacific ◽  
Intertidal Habitats ◽  
High Elevations ◽  
Intertidal Environments

Barnacle recruitment is often studied in rocky intertidal habitats due to the relevant role that barnacles can play in intertidal communities. In 2014, barnacle (Semibalanus balanoides) recruitment was measured at high elevations in wave-exposed intertidal habitats on the NW Atlantic coast in Nova Scotia, Canada. Values were considerably lower than previously reported for middle elevations in wave-exposed intertidal habitats on the NE Atlantic and NE Pacific coasts. To determine if such differences in recruitment may have resulted from elevation influences, I did a field experiment in 2019 in wave-exposed intertidal habitats in Nova Scotia to test the hypothesis that recruitment is higher at middle than at high elevations, based on known environmental differences between both elevation zones. Based on data from three locations spanning 158 km of the Nova Scotia coast, barnacle recruitment was, on average, nearly 200 % higher (and recruits were larger) at middle than at high elevations. However, even with this increase, barnacle recruitment on this NW Atlantic coast is still lower than for comparable habitats on the NE Atlantic and NE Pacific coasts, and also lower than previously reported for wave-exposed locations farther south on the NW Atlantic coast, in Maine, USA. Therefore, barnacle recruitment in wave-exposed intertidal environments in Nova Scotia appears to be only moderate relative to other shores. This difference in the supply of barnacle recruits might influence the intensity of interspecific interactions involving barnacles.

scholarly journals Heterozygous Trees Rebound the Fastest after Felling by Beavers to Positively Affect Arthropod Community Diversity

Forests ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 694
Author(s):  
Faith M. Walker ◽  
Rachel Durben ◽  
Stephen M. Shuster ◽  
Richard L. Lindroth ◽  
Thomas G. Whitham
Keyword(s):  
Genetic Diversity ◽  
Genetic Relatedness ◽  
Castor Canadensis ◽  
High Stress ◽  
Underlying Mechanism ◽  
Community Level ◽  
Community Diversity ◽  
Population Substructure ◽  
Individual Plant ◽  
Arthropod Community

Although genetic diversity within stands of trees is known to have community-level consequences, whether such effects are present at an even finer genetic scale is unknown. We examined the hypothesis that genetic variability (heterozygosity) within an individual plant would affect its dependent community, which adds a new dimension to the importance of genetic diversity. Our study contrasted foliar arthropod community diversity and microsatellite marker-derived measures of genetic diversity of cottonwood (Populus fremontii) trees that had been felled by beavers (Castor canadensis) and were resprouting, relative to adjacent standing, unfelled trees. Three patterns emerged: 1. Productivity (specific leaf area), phytochemical defenses (salicortin), and arthropod community richness, abundance, and diversity were positively correlated with the heterozygosity of individual felled trees, but not with that of unfelled trees; 2. These relationships were not explained by population substructure, genetic relatedness of the trees, or hybridization; 3. The underlying mechanism appears to be that beaver herbivory stimulates increased productivity (i.e., 2× increase from the most homozygous to the most heterozygous tree) that is the greatest in more heterozygous trees. Salicortin defenses in twigs were also expressed at higher concentrations in more heterozygous trees (i.e., 3× increase from the most homozygous to the most heterozygous tree), which suggests that this compound may dissuade further herbivory by beavers, as has been found for other mammalian herbivores. We suggest that high stress to trees as a consequence of felling reveals a heterozygosity–productivity linkage, which in turn is attractive to arthropods. Although experiments are required to demonstrate causality, these results link the genetic diversity of individual trees to community diversity, supporting the hypothesis that interactions among foundation species (beavers and trees) have community-level effects, and underscores the importance of genetic diversity for biodiversity, conservation, and restoration.

scholarly journals Succession in rocky intertidal benthic communities in areas with different pollution levels at Guanabara Bay (RJ-Brazil)

2005 ◽  
Vol 48 (6) ◽  
pp. 951-965 ◽  
Author(s):  
André Breves-Ramos ◽  
Helena Passeri Lavrado ◽  
Andrea de Oliveira Ribeiro Junqueira ◽  
Sérgio Henrique Gonçalves da Silva
Keyword(s):  
Community Development ◽  
Species Composition ◽  
Benthic Communities ◽  
Organic Pollution ◽  
Polluted Area ◽  
Rocky Intertidal ◽  
Percent Cover ◽  
Guanabara Bay ◽  
Pollution Levels ◽  
Resilient Communities

The aim of this study was to describe and compare the succession of intertidal benthic communities in two areas at Guanabara Bay, RJ, Brazil: Urca, an area submitted to moderated organic pollution and Catalão, an extremely polluted area. Three transects in each area were scraped one month before the beginning of this study in order to evaluate the recruitment (recruitment-treatments). Three other transects were monitored without manipulation (monitoring treatments). Species composition and relative abundance were evaluated monthly between September and December, 2000. A total of 26 species was found at Urca and 13 at Catalão. The percent cover of the most abundant organisms was not similar between treatments at Urca after four months, while in Catalão, the similarity was 72% in the second month. The faster community development and recovery at the most polluted area was probably related to the existence of simple and resilient communities in more impacted areas.

Dissolved organic matter as P source for biofilms in two contrasting low-order streams

2019 ◽  
Vol 193 (2) ◽  
pp. 131-142
Author(s):  
Verónica Díaz-Villanueva
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Deciduous Forest ◽  
Spatial Scales ◽  
Algal Species ◽  
Community Level ◽  
Nutrient Concentrations ◽  
Organic Substrates ◽  
One Year ◽  
Forest Streams

Forest streams receive large amounts of leaves whose leachates are an important source of dissolved organic matter (DOM), providing not only carbon but also organic nutrients to the microbial communities in streams. I carried out a field study to evaluate the effect of different DOM concentrations on the biofilm structure and functional traits in two similar forest streams belonging to the same catchment. I compared biofilm biomass and nutri- ent content throughout one year, algal species composition, and biofilm community-level physiological profiles in two streams with different DOM concentration and aromaticity. Dissolved nutrient concentrations were higher in the stream with higher DOM concentration, with a concomitant higher biofilm biomass, and there was also a temporal pattern, with higher values during the autumn. Phosphorus content in biofilms was also higher in the high DOM stream, coincidently with a higher capacity of the community to utilize organic P source (glucose-1-P) as a substrate. In contrast, the biofilms from the stream with lower DOM concentrations preferentially used N-organic substrates (amino acids and amines). These results reveal that the biofilms of forest streams make use of organic matter nutrients, so that streams with different DOM loads may differ in biofilm biomass due to changes in both bacterial and autotrophic biomass. In addition, biofilm dynamics may be related to forest phenology, as the highest OM input in this deciduous forest is represented by tree leaves, which supply DOM through leachates, and in particular, with P-rich leachates. In conclusion, different DOM concentrations in two nearby streams led to differences in the community-level physiological profile, as has been previously demonstrated at larger spatial scales in oceans, lakes and along larger rivers.

scholarly journals Benthic communities of shallow-water reefs of Abrolhos, Brazil

1997 ◽  
Vol 45 (1-2) ◽  
pp. 35-43 ◽  
Author(s):  
Roberto Villaça ◽  
Fábio B. Pitombo
Keyword(s):  
Shallow Water ◽  
Coral Species ◽  
Coral Cover ◽  
Benthic Communities ◽  
Algal Species ◽  
Percentage Cover ◽  
High Productivity ◽  
Fringing Reefs ◽  
Cover Ratio ◽  
Line Transects

The benthic communities of fringing and mushroom-shaped shallow-water reefs of the Abrolhos region (southern coast of Bahia) were surveyed. Line transects were used to estimate coral and algal percentage cover. Mussismilia braziliensis is the most conspicuous coral species in the majority of the communities surveyed, but turf algal make up the dominant cover in all but one studied reef. In general, communities on mushroom-shaped reefs have higher diversity and higher coral cover than on fringing reefs. For both reef morphologies, the coral to alga cover ratio does. not show marked differences between annual surveys, despite the high productivity characteristic of the dominant algal species.

scholarly journals Cryptic species in sympatry: Nonrandom small-scale distribution patterns in Bostrychia intricata (Ceramiales, Rhodophyta)

2020 ◽  
Author(s):  
N Muangmai ◽  
U Von Ammon ◽  
Giuseppe Zuccarello
Keyword(s):  
Cryptic Species ◽  
Algal Species ◽  
Sun Exposure ◽  
Distribution Patterns ◽  
Molecular Data ◽  
Small Scale ◽  
Ecological Resources ◽  
Intertidal Habitats ◽  
Multiple Species ◽  
Multiple Samples

© 2016 International Phycological Society. Sympatric coexistence of cryptic species, indistinguishable morphological taxa, has increasingly been detected on the basis of molecular data. This discovery raises the interesting question of how cryptic species can coexist, as hypothetically they would need identical ecological resources. The red alga Bostrychia intricata is commonly found along New Zealand shores. Previous studies indicated several cryptic species within this morphospecies, and that some populations have multiple species. This study aimed to determine how coexisting cryptic B. intricata distribute at a small scale. Along the shore of Moa Point, Wellington, we conducted intensive sampling of B. intricata in different habitats with respect to tidal position, wave and sun exposure levels. Our genetic data clearly documented the coexistence of three cryptic species of B. intricata: N2, N4 and N5. Multiple samples from individual algal patches indicated that each patch was made of the same ramet. Our analyses revealed a habitat-related pattern in small-scale distribution of different cryptic B. intricata, suggesting that the distribution of these cryptic species was not random. Cryptic species N4 was found at a higher tidal position than species N2 and N5, whereas cryptic species N2 occurred in more wave-exposed areas than the other species. Discriminant analysis indicated that tidal height strongly influenced the distribution pattern among these cryptic species. Our observations demonstrated that the co-occurrence of three cryptic B. intricata can partly be explained by their occupation of different intertidal habitats, highlighting the nonrandom distribution of coexisting cryptic algal species.

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