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 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 Ecological determinants of intertidal recruitment and metacommunity structure on the Atlantic coast of Nova Scotia

2018 ◽  
Author(s):  
Ricardo A. Scrosati ◽  
Julius A. Ellrich
Keyword(s):  
Nova Scotia ◽  
Atlantic Coast ◽  
Seawater Temperature ◽  
Rocky Intertidal ◽  
Late Winter ◽  
In Situ Data ◽  
Sessile Invertebrates ◽  
Filter Feeders ◽  
Metacommunity Structure ◽  
Rocky Habitats

Rocky-intertidal species are often distributed as metacommunities along marine shores, as rocky habitats are patchy. Nearshore pelagic conditions often explain variation among the local communities, but most studies have been done on eastern ocean boundary coasts. We investigated potential drivers of intertidal metacommunity structure on the Atlantic coast of Nova Scotia. We studied the high intertidal zone of nine wave-exposed bedrock locations spanning 425 km of coastline. At each location in the spring, we measured the recruitment of barnacles and mussels, the two predominant sessile invertebrates. Satellite data on coastal phytoplankton abundance and particulate organic carbon (food supply for intertidal filter-feeders) and in-situ data on coastal seawater temperature explained to varying degrees the geographic structure of recruitment. In turn, the summer abundance of both filter-feeders was positively related to their spring recruitment. Ultimately, predator (dogwhelk) abundance increased with the recruitment and abundance of barnacles and mussels (the main prey of dogwhelks), suggesting that bottom-up forcing influences metacommunity structure on this coast. Sea ice constituted an overlapping source of variation. Drift ice leaving the Gulf of St. Lawrence in late winter disturbed intertidal communities in the northern locations, limiting local biodiversity compared with central and southern locations.

scholarly journals Ecological determinants of intertidal recruitment and metacommunity structure on the Atlantic coast of Nova Scotia

2018 ◽  
Author(s):  
Ricardo A. Scrosati ◽  
Julius A. Ellrich
Keyword(s):  
Nova Scotia ◽  
Atlantic Coast ◽  
Seawater Temperature ◽  
Rocky Intertidal ◽  
Late Winter ◽  
In Situ Data ◽  
Sessile Invertebrates ◽  
Filter Feeders ◽  
Metacommunity Structure ◽  
Rocky Habitats

Rocky-intertidal species are often distributed as metacommunities along marine shores, as rocky habitats are patchy. Nearshore pelagic conditions often explain variation among the local communities, but most studies have been done on eastern ocean boundary coasts. We investigated potential drivers of intertidal metacommunity structure on the Atlantic coast of Nova Scotia. We studied the high intertidal zone of nine wave-exposed bedrock locations spanning 425 km of coastline. At each location in the spring, we measured the recruitment of barnacles and mussels, the two predominant sessile invertebrates. Satellite data on coastal phytoplankton abundance and particulate organic carbon (food supply for intertidal filter-feeders) and in-situ data on coastal seawater temperature explained to varying degrees the geographic structure of recruitment. In turn, the summer abundance of both filter-feeders was positively related to their spring recruitment. Ultimately, predator (dogwhelk) abundance increased with the recruitment and abundance of barnacles and mussels (the main prey of dogwhelks), suggesting that bottom-up forcing influences metacommunity structure on this coast. Sea ice constituted an overlapping source of variation. Drift ice leaving the Gulf of St. Lawrence in late winter disturbed intertidal communities in the northern locations, limiting local biodiversity compared with central and southern locations.

scholarly journals Subarctic shores without an ice foot: Low extremes in intertidal temperature during winter

2020 ◽  
Author(s):  
Ricardo Augusto Scrosati
Keyword(s):  
Nova Scotia ◽  
Minimum Temperature ◽  
Intertidal Zone ◽  
Freezing Point ◽  
Atlantic Coast ◽  
Daily Minimum Temperature ◽  
Absolute Minimum ◽  
Daily Minimum ◽  
Air Temperatures ◽  
Intertidal Habitats

On marine shores that freeze in winter, the intertidal zone becomes covered by an ice foot. Stable ice foots insulate intertidal organisms against highly negative air temperatures. On subpolar intertidal habitats that do not freeze, the periodic inundation with seawater at temperatures near its freezing point also prevents benthic organisms from experiencing highly negative temperatures. However, low tides do expose ice-free intertidal habitats to aerial conditions, but information on how negative temperature gets there during the winter is lacking. Using data loggers, this study measured the daily lowest temperature in rocky intertidal habitats on the Atlantic coast of Nova Scotia, Canada (which does not freeze), during the winter. As a control, temperature was also monitored above the intertidal zone (on tree branches). Intertidal temperature was almost as low as supratidal temperature, as the seasonal averages of daily minimum temperature were -4.2 °C and -6.4 °C (with absolute minima of -14.1 °C and -19.1 °C), respectively. The study site on the Atlantic coast is climatically similar to a site surveyed on the Gulf of St. Lawrence coast of Nova Scotia. However, the Gulf of St. Lawrence coast, which freezes in winter, showed milder intertidal temperatures, with a winter average of daily minimum temperature of -1.9 °C and an absolute minimum of only -6.8 °C. Therefore, despite tidal influences, the absence of an ice foot exposes subpolar intertidal habitats to highly negative air temperatures.

scholarly journals First visual record of rare purple-colored dogwhelks (Nucella lapillus) on the Atlantic coast of Nova Scotia, Canada

F1000Research ◽  
2017 ◽  
Vol 5 ◽  
pp. 2435
Author(s):  
Sonja M. Ehlers ◽  
Julius A. Ellrich
Keyword(s):  
Nova Scotia ◽  
Field Experiments ◽  
Atlantic Coast ◽  
Rocky Intertidal ◽  
Bay Of Fundy ◽  
Nucella Lapillus ◽  
Shell Color ◽  
The North ◽  
Intertidal Gastropod ◽  
Visual Record

The dogwhelk Nucella lapillus is a rocky intertidal gastropod of the North Atlantic coast. Individual shell color varies. Common colors range between white and brown, with darker dogwhelks being more affected by heat stress than lighter-colored conspecifics. Other reported shell colors are purple, black, mauve, pink, yellow, and orange from UK coasts, red and gray from the Bay of Fundy coast of New Brunswick and Nova Scotia (Canada), and purple, black, gray, yellow, and orange from the coasts of Maine and Massachusetts (USA), with purple being considered as a rare color. On the Atlantic coast of Nova Scotia, dogwhelks are active from April until November, but information on dogwhelk shell color is missing for this coast. On 16 June 2016, we found two purple-colored dogwhelks in the mid-to-high intertidal zone of a moderately wave-exposed rocky shore near Duncans Cove, on the Atlantic coast of Nova Scotia while collecting dogwhelks (n= 1000) during low tide for manipulative field experiments. All other dogwhelks collected on that day were of common white and brown colors. During earlier dogwhelk collections in Atlantic Nova Scotia (between 2011-2013) and field surveys in Duncans Cove (between 2014-2016), we did not find any purple-colored dogwhelks, indicating the rareness of this color in that region. Apparently, our observations provide the first visual record of rare purple-colored dogwhelks on the Atlantic coast of Nova Scotia, Canada.

scholarly journals First visual record of rare purple dogwhelks (Nucella lapillus) on the Atlantic coast of Nova Scotia, Canada

F1000Research ◽  
2016 ◽  
Vol 5 ◽  
pp. 2435
Author(s):  
Sonja M. Ehlers ◽  
Julius A. Ellrich
Keyword(s):  
Nova Scotia ◽  
Field Experiments ◽  
Atlantic Coast ◽  
Rocky Intertidal ◽  
Bay Of Fundy ◽  
Nucella Lapillus ◽  
Shell Color ◽  
The North ◽  
Intertidal Gastropod ◽  
Visual Record

The dogwhelk Nucella lapillus is a rocky intertidal gastropod of the North Atlantic coast. Individual shell color varies. Common colors range between white and brown, with darker dogwhelks being more affected by heat stress than lighter-colored conspecifics. Other reported shell colors are black, mauve, pink, yellow, and orange from European coasts, red and grey from the Bay of Fundy coast of New Brunswick and Nova Scotia (Canada), and purple, black, gray, yellow, and orange from the coasts of Maine and Massachusetts (USA), with purple being considered as a rare color. On the Atlantic coast of Nova Scotia, dogwhelks are active from April until November, but information on dogwhelk shell color is missing for this coast. On 16 June 2016, we found two purple dogwhelks in the mid-to-high intertidal zone of a moderately wave-exposed rocky shore near Duncans Cove, on the Atlantic coast of Nova Scotia while collecting dogwhelks (n= 1000) for manipulative field experiments. All other dogwhelks collected on that day were of common white and brown colors. During earlier dogwhelk collections in Atlantic Nova Scotia (between 2011-2013) and field surveys in Duncans Cove (between 2014-2016), we did not find any purple dogwhelks, indicating the rareness of this color in that region. Interestingly, the purple dogwhelks were detected on a relatively cool day (12.3 ± 0.4 °C, mean ± se, n= 96 temperature measurements) compared to the intertidal temperatures of all other survey days (≥ 18.2 ± 0.5 °C), suggesting that purple dogwhelks may find it less thermally stressful to venture out of crevices and macroalgal cover under relatively cool temperatures. Our observations provide the first visual record of rare purple dogwhelks on the Atlantic coast of Nova Scotia, Canada.

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 Ecological determinants of intertidal recruitment and metacommunity structure on the Atlantic coast of Nova Scotia

2018 ◽  
Author(s):  
Ricardo A. Scrosati ◽  
Julius A. Ellrich
Keyword(s):  
Nova Scotia ◽  
Atlantic Coast ◽  
Seawater Temperature ◽  
Rocky Intertidal ◽  
Late Winter ◽  
In Situ Data ◽  
Sessile Invertebrates ◽  
Filter Feeders ◽  
Metacommunity Structure ◽  
Rocky Habitats

Rocky-intertidal species are often distributed as metacommunities along marine shores, as rocky habitats are patchy. Nearshore pelagic conditions often explain variation among the local communities, but most studies have been done on eastern ocean boundary coasts. We investigated potential drivers of intertidal metacommunity structure on the Atlantic coast of Nova Scotia. We studied the high intertidal zone of nine wave-exposed bedrock locations spanning 415 km of coastline. At each location in the spring, we measured the recruitment of barnacles and mussels, the two predominant sessile invertebrates. Satellite data on coastal phytoplankton abundance and particulate organic carbon (food supply for intertidal filter-feeders) and in-situ data on coastal seawater temperature explained to varying degrees the geographic structure of recruitment. In turn, the summer abundance of both filter-feeders was positively related to their spring recruitment. Ultimately, predator (dogwhelk) abundance increased with the recruitment and abundance of barnacles and mussels (the main prey of dogwhelks), suggesting that bottom-up forcing influences metacommunity structure on this coast. Sea ice constituted an overlapping source of variation. Drift ice leaving the Gulf of St. Lawrence in late winter disturbed intertidal communities in the northern locations, limiting local biodiversity compared with central and southern locations.

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.

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