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S. J. Hawkins - One of the best experts on this subject based on the ideXlab platform.
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Phenotypic variation in shell form in the intertidal acorn barnacle Chthamalus montagui: distribution, response to predators and life history trade-offs
Marine Biology, 2014Co-Authors: Jefferson Murua, S. J. Hawkins, Michael T. Burrows, Roger N. Hughes, Richard C. Thompson, Stuart R. JenkinsAbstract:The acorn barnacle Chthamalus montagui can present strong variation in shell morphology, ranging from flat conic to a highly bent form, caused by a substantial overgrowth of the rostrum plate. Shell shape distribution was investigated between January and May 2004 from geographical to microhabitat spatial scales along the western coast of Britain. Populations studied in the north (Scotland and Isle of Man) showed a higher degree of shell variation compared to those in the south (Wales and south-west England). In the north, C. montagui living at lower tidal levels and in proximity to the predatory dogwhelk, Nucella lapillus, were more bent in profile. Laboratory experiments were conducted to examine behavioural responses, and vulnerability of bent and conic barnacles to predation by N. lapillus. Dogwhelks did not attack one morphotype more than the other, but only 15 % of attacks on bent forms were successful compared to 75 % in conic forms. Dogwhelk effluent reduced the time spent feeding by C. montagui (11 %), but there was no significant difference between conic and bent forms. Examination of barnacle morphology indicated a trade-off in investment in shell structure and feeding appendages associated with being bent, but none with egg or somatic tissue mass. These results are consistent with C. montagui showing an induced defence comparable to that found in its congeners Chthamalus anisopoma and Chthamalus fissus on the Pacific coast of North America, but further work to demonstrate inducibility is required.
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Tidal rates of settlement of the intertidal barnacles Chthamalus stellatus and Chthamalus montagui in western Europe: The influence of the night/day cycle
Journal of Experimental Marine Biology and Ecology, 2005Co-Authors: Teresa Cruz, João J. Castro, Jane Delany, David Mcgrath, Alan A. Myers, Ruth M. O'riordan, Anne Marie Power, J. Rabaça, S. J. HawkinsAbstract:Abstract Chthamalus montagui and Chthamalus stellatus are abundant barnacles in western Europe. Tidal settlement of Chthamalus in SW Ireland and SW Portugal was studied in relation to a night and day factor and at different temporal (dates) and spatial (shores and sites) scales. Based on the identifiable cyprids and metamorphs, Chthamalus settlement in SW Ireland was comprised mainly of C. stellatus but was composed of C. montagui only in SW Portugal. In SW Ireland and SW Portugal, settlement rates of Chthamalus (mean number of settlers per 25 cm2±S.E.) were higher after one day tidal cycle (597±158.7 in SW Ireland, 144±23.6 in SW Portugal) than one night tidal cycle (55±12.1 in SW Ireland, 13±2.2 in SW Portugal), but significant differences were only detected in SW Portugal. Different models were proposed for explaining this pattern related to night and day variability of the physical processes responsible for transporting cyprids to shore (1), and/or of pre-settlement behaviour (2) and/or of settlement behaviour of cyprids (3). Spatial patterns of tidal settlement of both species or at both locations seem similar with small scale variability (between sites, 5 to 30 m apart) in settlement of Chthamalus being the only spatial scale at which variability was detected in both locations. The composition of Chthamalus cohorts settling during one tidal cycle differed considerably between locations/species: settlers of C. stellatus were mainly cyprids; settlers of C. montagui during the day (when most settlement occurred) were essentially metamorphs.
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Isolation of highly polymorphic microsatellite markers from the intertidal barnacle Chthamalus montagui Southward
Molecular Ecology Notes, 2005Co-Authors: Federica G. Pannacciulli, S. J. Hawkins, Sanit Piyapattanakorn, John D. D. Bishop, Norman MacleanAbstract:This study reports the isolation and characterization of seven highly polymorphic microsatellite loci in Chthamalus montagui (Crustacea, Cirripedia). The loci were isolated from a library constructed from genomic DNA enriched for CA repeats. The markers yielded three to 43 alleles per locus (mean 16.7) in samples averaging 49 individuals. Observed heterozygosity ranged from 0.08 to 0.58 (mean 0.39). These microsatellite loci will be valuable tools for population genetic studies of this species.
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Spatial variation in the recruitment of the intertidal barnacles Chthamalus montagui Southward and Chthamalus stellatus (Poli) (Crustacea: Cirripedia) over an European scale
Journal of Experimental Marine Biology and Ecology, 2004Co-Authors: Ruth M. O'riordan, Teresa Cruz, João J. Castro, Jane Delany, S. J. Hawkins, Francisco Arenas, Julio Arrontes, Brezo Martínez, Consolación Fernández, David McgrathAbstract:Spatial variation in the recruitment of the intertidal barnacles Chthamalus montagui and Chthamalus stellatus was examined over an European scale. The study was carried out using standardised protocols at a series of locations. The five locations chosen (SW Ireland, NW Spain, SW Portugal and NW and NE Italy) span a large part of the range of these species in Europe. The spatial scales were location (hundreds of kilometres) and shore (thousands of metres). Estimates of total cumulative recruitment (cyprids and metamorphs) summed over the year (April 1997 to March 1998) showed substantial variation between locations which was dependent on the species. Recruitment was highest in SW Portugal for C. montagui and in SW Ireland and NW Spain for C. stellatus. Overall recruitment of C. montagui was higher than that of C. stellatus at all locations except SW Ireland, where recruitment of the two species was not significantly different. There were significant differences among shores in each location. The recruitment period of both species varied with location, with recruitment beginning earlier further south. In general, recruitment of C. montagui and C. stellatus was recorded in 8 months in NW Spain and NE Italy, while only in 7 months in SW Ireland. Recruitment of C. montagui occurred in 10 months in SW Portugal, but no recruits of C. stellatus were found. In all locations there was at least one distinct peak of recruitment. In SW Ireland both species showed only one peak of recruitment, a month after initiation. At the more southerly Atlantic locations, as well as in the Mediterranean, two unequal peaks of recruitment were generally seen. During recruit census, the number of cyprids, in comparison to metamorphs, found at any location was very low. In SW Ireland and NW Spain cyprids of both species were found, while in SW Portugal and in the Mediterranean, only cyprids of C. montagui were found.
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A KEY FOR THE IDENTIFICATION OF THE NAUPLII OF COMMON BARNACLES OF THE BRITISH ISLES, WITH EMPHASIS ON Chthamalus
Journal of Crustacean Biology, 2003Co-Authors: Pauline M. Ross, S. J. Hawkins, Alan J. Southward, Michael T. Burrows, Keith P RyanAbstract:Abstract Chthamalus stellatus and C. montagui are warm-water barnacles common on rocky shores in southwest England, Ireland, and southern Europe. They are partly sympatric, with overlapping vertical and horizontal distributions. It has been suggested that the differing horizontal distribution of the adults may be related to differences in the distribution of the larval stages. To this end, we have examined plankton samples taken during the summer breeding period at Plymouth, from inshore to 15 miles offshore. The samples also contained large numbers of other cirriped nauplii, notably Elminius modestus, Balanus perforatus, B. crenatus, and Verruca stroemia, from which the chthamalids had to be distinguished. The chthamalids can be separated from the other nauplii by use of characters that include a unilobed or trilobed labrum, the length of posterior processes and the shape and size of the cephalic shield, but the two species of Chthamalus are more difficult to distinguish. Scanning electron microscopy (S....
Teresa Cruz - One of the best experts on this subject based on the ideXlab platform.
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Tidal settlement of the intertidal barnacles Chthamalus spp. in SW Portugal: interaction between diel and semi-lunar cycles
Marine Ecology Progress Series, 2008Co-Authors: David Jacinto, Teresa CruzAbstract:Patterns and processes of tidal settlement (within 1 tidal cycle) of Chthamalus spp. in SW Portugal were investigated during the summer of 2003. Settlement patterns in relation to differ- ent periods of the day (night and day) and semi-lunar tidal cycles (spring and neap tides) were assessed using artificial plates deployed in intertidal habitats dominated by C. montagui. Settlement of Chthamalus spp. varied at all temporal and spatial scales considered in this study. A strong inter- action between diel and semi-lunar tidal cycles was detected. Settlement was higher during diurnal spring tides (afternoon) than during diurnal and nocturnal neap tides (morning and early night) and was lowest during nocturnal spring tides (late night). In order to investigate putative physical mech- anisms of shoreward transport to explain our observations, the tidal variability of several physical variables (wind stress, seawater temperature and temperature stratification) was individually inves- tigated and correlated with settlement. Onshore wind stress was positively correlated with settle- ment, and exhibited the same night/day and tidal pattern. Onshore wind forcing could be acting as a mechanism promoting intensive larval delivery to the shore in the afternoon (sea breeze) and off- shore retention late at night, leading to the high frequency variability patterns observed in barnacle settlement.
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Tidal rates of settlement of the intertidal barnacles Chthamalus stellatus and Chthamalus montagui in western Europe: The influence of the night/day cycle
Journal of Experimental Marine Biology and Ecology, 2005Co-Authors: Teresa Cruz, João J. Castro, Jane Delany, David Mcgrath, Alan A. Myers, Ruth M. O'riordan, Anne Marie Power, J. Rabaça, S. J. HawkinsAbstract:Abstract Chthamalus montagui and Chthamalus stellatus are abundant barnacles in western Europe. Tidal settlement of Chthamalus in SW Ireland and SW Portugal was studied in relation to a night and day factor and at different temporal (dates) and spatial (shores and sites) scales. Based on the identifiable cyprids and metamorphs, Chthamalus settlement in SW Ireland was comprised mainly of C. stellatus but was composed of C. montagui only in SW Portugal. In SW Ireland and SW Portugal, settlement rates of Chthamalus (mean number of settlers per 25 cm2±S.E.) were higher after one day tidal cycle (597±158.7 in SW Ireland, 144±23.6 in SW Portugal) than one night tidal cycle (55±12.1 in SW Ireland, 13±2.2 in SW Portugal), but significant differences were only detected in SW Portugal. Different models were proposed for explaining this pattern related to night and day variability of the physical processes responsible for transporting cyprids to shore (1), and/or of pre-settlement behaviour (2) and/or of settlement behaviour of cyprids (3). Spatial patterns of tidal settlement of both species or at both locations seem similar with small scale variability (between sites, 5 to 30 m apart) in settlement of Chthamalus being the only spatial scale at which variability was detected in both locations. The composition of Chthamalus cohorts settling during one tidal cycle differed considerably between locations/species: settlers of C. stellatus were mainly cyprids; settlers of C. montagui during the day (when most settlement occurred) were essentially metamorphs.
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Spatial variation in the recruitment of the intertidal barnacles Chthamalus montagui Southward and Chthamalus stellatus (Poli) (Crustacea: Cirripedia) over an European scale
Journal of Experimental Marine Biology and Ecology, 2004Co-Authors: Ruth M. O'riordan, Teresa Cruz, João J. Castro, Jane Delany, S. J. Hawkins, Francisco Arenas, Julio Arrontes, Brezo Martínez, Consolación Fernández, David McgrathAbstract:Spatial variation in the recruitment of the intertidal barnacles Chthamalus montagui and Chthamalus stellatus was examined over an European scale. The study was carried out using standardised protocols at a series of locations. The five locations chosen (SW Ireland, NW Spain, SW Portugal and NW and NE Italy) span a large part of the range of these species in Europe. The spatial scales were location (hundreds of kilometres) and shore (thousands of metres). Estimates of total cumulative recruitment (cyprids and metamorphs) summed over the year (April 1997 to March 1998) showed substantial variation between locations which was dependent on the species. Recruitment was highest in SW Portugal for C. montagui and in SW Ireland and NW Spain for C. stellatus. Overall recruitment of C. montagui was higher than that of C. stellatus at all locations except SW Ireland, where recruitment of the two species was not significantly different. There were significant differences among shores in each location. The recruitment period of both species varied with location, with recruitment beginning earlier further south. In general, recruitment of C. montagui and C. stellatus was recorded in 8 months in NW Spain and NE Italy, while only in 7 months in SW Ireland. Recruitment of C. montagui occurred in 10 months in SW Portugal, but no recruits of C. stellatus were found. In all locations there was at least one distinct peak of recruitment. In SW Ireland both species showed only one peak of recruitment, a month after initiation. At the more southerly Atlantic locations, as well as in the Mediterranean, two unequal peaks of recruitment were generally seen. During recruit census, the number of cyprids, in comparison to metamorphs, found at any location was very low. In SW Ireland and NW Spain cyprids of both species were found, while in SW Portugal and in the Mediterranean, only cyprids of C. montagui were found.
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Distribution and abundance of co-occurring chthamalid barnacles Chthamalus montagui and Chthamalus stellatus (Crustacea, Cirripedia) on the southwest coast of Portugal
Hydrobiologia, 2000Co-Authors: E. B. Sousa, Teresa Cruz, João J. CastroAbstract:Two co-occurring chthamalid barnacle species occur on the rocky shores of continental Portugal: Chthamalus stellatus (Poli) and Chthamalus montagui Southward. In the present study, patterns of distribution and abundance (density and percentage cover), both vertically (tidal level) and horizontally (wave action), were studied for each species on headlands (more wave action) and not on headlands (less wave action) and at two spatial scales (shore and site) and three tidal levels (low, mid and upper). Chthamalus montagui was significantly more abundant than C. stellatus in both degrees of wave action and at all tidal levels. Despite this great difference in abundance and considering each species individually, C. montagui was more abundant at mid tide-level, while C. stellatus was more abundant at the low tide-level, and C. montagui was less abundant on headlands, while C. stellatus was more abundant on headlands. Small-scale variability (between sites, tens of meters) of abundance of each species was detected, while differences on a larger scale (between shores, tens of kilometres) were not significant.
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Settlement patterns of Chthamalus spp. at Praia da Oliveirinha (SW Portugal)
Acta Oecologica, 1999Co-Authors: Teresa CruzAbstract:Abstract Recruitment of Chthamalus spp. is intense during spring and summer but the number of settled cypris larvae is very low when compared to the high number of Chthamalus spp. metamorphs. In the summer of 1997 at Praia da Oliveirinha (SW Portugal), two hypotheses were tested: 1) the cypris larvae of Chthamalus spp. metamorphose in one tidal cycle; and 2) the settlement of Chthamalus spp. is higher during diurnal high tide compared with nocturnal high tide. The results indicate that cypris larvae of Chthamalus spp. can metamorphose in one tidal cycle. The hypothesis of higher settlement during diurnal high tide could not be tested at the mid and upper levels of C. montagui distribution due to a significative heterogeneity of variances. At the lower level, the results support this hypothesis. In spite of these data having been collected on a single shore and on a few sampling dates, these results suggest that more studies using different spatial and temporal scales are needed to see if this pattern is general.
Ruth M. O'riordan - One of the best experts on this subject based on the ideXlab platform.
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Factors, at different scales, affecting the distribution of species of the genus Chthamalus Ranzani (Cirripedia, Balanomorpha, Chthamaloidea)
Journal of Experimental Marine Biology and Ecology, 2010Co-Authors: Ruth M. O'riordan, Anne Marie Power, Alan A. MyersAbstract:Abstract This paper reviews what is known about the factors affecting the distribution of barnacle species of the genus Chthamalus Ranzani at global, regional, local and microhabitat spatial scales. The genus is almost worldwide in distribution, on tropical and temperate shores, with currently over twenty recognised species. The majority of members of this genus commonly occur in the middle and upper intertidal. At the global scale (1000s km), the four currently recognised informal groups of Chthamalus exhibit a regional endemicity that has probably resulted from tectonic events during the last 70-90 Ma. The 'challengeri' and 'fissus' groups are thought to be the most ancestral within Chthamalus . Their extant distributions derive from the late Cretaceous. The 'malayensis' and 'stellatus' groups are assumed to be more derived and are probably sister taxa. The latter two groups exhibit overlap with the apparently more ancient 'challengeri' and 'fissus' groups. Abiotic factors (e.g. temperature, desiccation, aspect, winds and fetch) together with biotic factors (e.g. supply-side) all affect the distribution of Chthamalus species at regional (100s km) and local (1-10s km) scales. The relationship between these factors and Chthamalus distributions has best been studied in the north-east Atlantic species C. stellatus and C. montagui and to a lesser extent in the western Atlantic species C. fragilis . Microhabitat (within shore) patterns of distribution in Chthamalus barnacles are controlled by biotic (e.g. supply-side, competition, predation and grazer/algal interactions) and abiotic (e.g. shading and run-off) factors. The highly fluctuating temperatures and desiccation stress that Chthamalus species experience when aerially exposed at low tide appear to have a major deterministic effect on species distributions, often limiting the vertical distribution of Chthamalus species on the shore. On sheltered shores, the abiotic stress due to minimal wave splash may be more important than biotic factors, while on moderately exposed and exposed shores, that can be supplied with many propagules and where density-dependent factors come into play, biotic factors may be more important. Abiotic factors may also scale up to explain large scale patterns of distribution, such as trends in Chthamalus abundance between NE and SE Atlantic coasts.
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Tidal rates of settlement of the intertidal barnacles Chthamalus stellatus and Chthamalus montagui in western Europe: The influence of the night/day cycle
Journal of Experimental Marine Biology and Ecology, 2005Co-Authors: Teresa Cruz, João J. Castro, Jane Delany, David Mcgrath, Alan A. Myers, Ruth M. O'riordan, Anne Marie Power, J. Rabaça, S. J. HawkinsAbstract:Abstract Chthamalus montagui and Chthamalus stellatus are abundant barnacles in western Europe. Tidal settlement of Chthamalus in SW Ireland and SW Portugal was studied in relation to a night and day factor and at different temporal (dates) and spatial (shores and sites) scales. Based on the identifiable cyprids and metamorphs, Chthamalus settlement in SW Ireland was comprised mainly of C. stellatus but was composed of C. montagui only in SW Portugal. In SW Ireland and SW Portugal, settlement rates of Chthamalus (mean number of settlers per 25 cm2±S.E.) were higher after one day tidal cycle (597±158.7 in SW Ireland, 144±23.6 in SW Portugal) than one night tidal cycle (55±12.1 in SW Ireland, 13±2.2 in SW Portugal), but significant differences were only detected in SW Portugal. Different models were proposed for explaining this pattern related to night and day variability of the physical processes responsible for transporting cyprids to shore (1), and/or of pre-settlement behaviour (2) and/or of settlement behaviour of cyprids (3). Spatial patterns of tidal settlement of both species or at both locations seem similar with small scale variability (between sites, 5 to 30 m apart) in settlement of Chthamalus being the only spatial scale at which variability was detected in both locations. The composition of Chthamalus cohorts settling during one tidal cycle differed considerably between locations/species: settlers of C. stellatus were mainly cyprids; settlers of C. montagui during the day (when most settlement occurred) were essentially metamorphs.
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Spatial variation in the recruitment of the intertidal barnacles Chthamalus montagui Southward and Chthamalus stellatus (Poli) (Crustacea: Cirripedia) over an European scale
Journal of Experimental Marine Biology and Ecology, 2004Co-Authors: Ruth M. O'riordan, Teresa Cruz, João J. Castro, Jane Delany, S. J. Hawkins, Francisco Arenas, Julio Arrontes, Brezo Martínez, Consolación Fernández, David McgrathAbstract:Spatial variation in the recruitment of the intertidal barnacles Chthamalus montagui and Chthamalus stellatus was examined over an European scale. The study was carried out using standardised protocols at a series of locations. The five locations chosen (SW Ireland, NW Spain, SW Portugal and NW and NE Italy) span a large part of the range of these species in Europe. The spatial scales were location (hundreds of kilometres) and shore (thousands of metres). Estimates of total cumulative recruitment (cyprids and metamorphs) summed over the year (April 1997 to March 1998) showed substantial variation between locations which was dependent on the species. Recruitment was highest in SW Portugal for C. montagui and in SW Ireland and NW Spain for C. stellatus. Overall recruitment of C. montagui was higher than that of C. stellatus at all locations except SW Ireland, where recruitment of the two species was not significantly different. There were significant differences among shores in each location. The recruitment period of both species varied with location, with recruitment beginning earlier further south. In general, recruitment of C. montagui and C. stellatus was recorded in 8 months in NW Spain and NE Italy, while only in 7 months in SW Ireland. Recruitment of C. montagui occurred in 10 months in SW Portugal, but no recruits of C. stellatus were found. In all locations there was at least one distinct peak of recruitment. In SW Ireland both species showed only one peak of recruitment, a month after initiation. At the more southerly Atlantic locations, as well as in the Mediterranean, two unequal peaks of recruitment were generally seen. During recruit census, the number of cyprids, in comparison to metamorphs, found at any location was very low. In SW Ireland and NW Spain cyprids of both species were found, while in SW Portugal and in the Mediterranean, only cyprids of C. montagui were found.
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An investigation into rock surface wetness as a parameter contributing to the distribution of the intertidal barnacles Chthamalus stellatus and Chthamalus montagui
Estuarine Coastal and Shelf Science, 2001Co-Authors: Anne Marie Power, Alan A. Myers, David Mcgrath, Ruth M. O'riordan, Jane DelanyAbstract:Areas which were under the influence of runoff seeping slowly from upshore rockpools were identified at two shores in Co. Cork, Ireland. Surveys of adult and 0+Chthamalus stellatus and C. montagui were carried out in these areas and compared with adjacent dry areas. A second survey on cleared quadrats examined barnacle abundance in wet and in dry areas at 1 and 5 months after the initiation of settlement. Chthamalus stellatus adults and 0+ individuals were significantly more abundant in wet areas than in dry areas, which in the context of previous laboratory findings suggest that desiccation or some other parameter associated with wetness may be an important factor in limiting the vertical distribution of this species. Chthamalus montagui adults and 0+ individuals were significantly more abundant in dry areas than in wet areas. The lower vertical limit of this species may therefore also be set by some wetness parameter. In 1 month and 5 month old stages, the differences in abundance between wet and dry conditions were apparent in both species but were only significant in both age classes of C. montagui at one of the study shores. The results are discussed in the context of vertical and geographical distribution patterns exhibited by adults of each species on European shores.
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Prolonged settlement and prediction of recruitment in two sympatric intertidal Chthamalus species from south-west Ireland
Journal of the Marine Biological Association of the United Kingdom, 1999Co-Authors: Anne Marie Power, Jane Delany, Alan A. Myers, Ruth M. O'riordan, David McgrathAbstract:Attached cypris larvae and less than one month old metamorphs of Chthamalus stellatus and C. montagui (Crustacea: Cirripedia) were sampled from random quadrats on two shores in County Cork, Ireland, from July 1996 to June 1997. Cyprids of C. stellatus were much more abundant than those of C. montagui , but the relative abundance of metamorphs of the two species did not differ significantly. Cyprid abundance predicted metamorph recruitment intensity during peak settlement in C. stellatus but not in C. montagui .
Benny K. K. Chan - One of the best experts on this subject based on the ideXlab platform.
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Diagnostic morphological comparisons of arthropodal characters of Chthamalus in TPE.
2016Co-Authors: Benny K. K. Chan, A. J. Southward, -n. H. Chen, P. R. Dando, E. C. SouthwardAbstract:Diagnostic morphological comparisons of arthropodal characters of Chthamalus in TPE.
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Distribution of the Mexican species of Chthamalus examined by electrophoresis.
2016Co-Authors: Benny K. K. Chan, A. J. Southward, -n. H. Chen, P. R. Dando, E. C. SouthwardAbstract:Distribution of the Mexican species of Chthamalus examined by electrophoresis.
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Distribution of species of Chthamalus in Panama by enzyme electrophoresis.
2016Co-Authors: Benny K. K. Chan, A. J. Southward, -n. H. Chen, P. R. Dando, E. C. SouthwardAbstract:Distribution of species of Chthamalus in Panama by enzyme electrophoresis.
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Diagnostic enzyme mobility differences between species of Chthamalus in the North-eastern Pacific.
2016Co-Authors: Benny K. K. Chan, A. J. Southward, -n. H. Chen, P. R. Dando, E. C. SouthwardAbstract:Diagnostic enzyme mobility differences between species of Chthamalus in the North-eastern Pacific.
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Segment counts (n = 5 individuals) of Chthamalus in the Tropical Eastern Pacific waters.
2016Co-Authors: Benny K. K. Chan, A. J. Southward, -n. H. Chen, P. R. Dando, E. C. SouthwardAbstract:Segment counts (n = 5 individuals) of Chthamalus in the Tropical Eastern Pacific waters.
Alan A. Myers - One of the best experts on this subject based on the ideXlab platform.
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Factors, at different scales, affecting the distribution of species of the genus Chthamalus Ranzani (Cirripedia, Balanomorpha, Chthamaloidea)
Journal of Experimental Marine Biology and Ecology, 2010Co-Authors: Ruth M. O'riordan, Anne Marie Power, Alan A. MyersAbstract:Abstract This paper reviews what is known about the factors affecting the distribution of barnacle species of the genus Chthamalus Ranzani at global, regional, local and microhabitat spatial scales. The genus is almost worldwide in distribution, on tropical and temperate shores, with currently over twenty recognised species. The majority of members of this genus commonly occur in the middle and upper intertidal. At the global scale (1000s km), the four currently recognised informal groups of Chthamalus exhibit a regional endemicity that has probably resulted from tectonic events during the last 70-90 Ma. The 'challengeri' and 'fissus' groups are thought to be the most ancestral within Chthamalus . Their extant distributions derive from the late Cretaceous. The 'malayensis' and 'stellatus' groups are assumed to be more derived and are probably sister taxa. The latter two groups exhibit overlap with the apparently more ancient 'challengeri' and 'fissus' groups. Abiotic factors (e.g. temperature, desiccation, aspect, winds and fetch) together with biotic factors (e.g. supply-side) all affect the distribution of Chthamalus species at regional (100s km) and local (1-10s km) scales. The relationship between these factors and Chthamalus distributions has best been studied in the north-east Atlantic species C. stellatus and C. montagui and to a lesser extent in the western Atlantic species C. fragilis . Microhabitat (within shore) patterns of distribution in Chthamalus barnacles are controlled by biotic (e.g. supply-side, competition, predation and grazer/algal interactions) and abiotic (e.g. shading and run-off) factors. The highly fluctuating temperatures and desiccation stress that Chthamalus species experience when aerially exposed at low tide appear to have a major deterministic effect on species distributions, often limiting the vertical distribution of Chthamalus species on the shore. On sheltered shores, the abiotic stress due to minimal wave splash may be more important than biotic factors, while on moderately exposed and exposed shores, that can be supplied with many propagules and where density-dependent factors come into play, biotic factors may be more important. Abiotic factors may also scale up to explain large scale patterns of distribution, such as trends in Chthamalus abundance between NE and SE Atlantic coasts.
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Tidal rates of settlement of the intertidal barnacles Chthamalus stellatus and Chthamalus montagui in western Europe: The influence of the night/day cycle
Journal of Experimental Marine Biology and Ecology, 2005Co-Authors: Teresa Cruz, João J. Castro, Jane Delany, David Mcgrath, Alan A. Myers, Ruth M. O'riordan, Anne Marie Power, J. Rabaça, S. J. HawkinsAbstract:Abstract Chthamalus montagui and Chthamalus stellatus are abundant barnacles in western Europe. Tidal settlement of Chthamalus in SW Ireland and SW Portugal was studied in relation to a night and day factor and at different temporal (dates) and spatial (shores and sites) scales. Based on the identifiable cyprids and metamorphs, Chthamalus settlement in SW Ireland was comprised mainly of C. stellatus but was composed of C. montagui only in SW Portugal. In SW Ireland and SW Portugal, settlement rates of Chthamalus (mean number of settlers per 25 cm2±S.E.) were higher after one day tidal cycle (597±158.7 in SW Ireland, 144±23.6 in SW Portugal) than one night tidal cycle (55±12.1 in SW Ireland, 13±2.2 in SW Portugal), but significant differences were only detected in SW Portugal. Different models were proposed for explaining this pattern related to night and day variability of the physical processes responsible for transporting cyprids to shore (1), and/or of pre-settlement behaviour (2) and/or of settlement behaviour of cyprids (3). Spatial patterns of tidal settlement of both species or at both locations seem similar with small scale variability (between sites, 5 to 30 m apart) in settlement of Chthamalus being the only spatial scale at which variability was detected in both locations. The composition of Chthamalus cohorts settling during one tidal cycle differed considerably between locations/species: settlers of C. stellatus were mainly cyprids; settlers of C. montagui during the day (when most settlement occurred) were essentially metamorphs.
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An investigation into rock surface wetness as a parameter contributing to the distribution of the intertidal barnacles Chthamalus stellatus and Chthamalus montagui
Estuarine Coastal and Shelf Science, 2001Co-Authors: Anne Marie Power, Alan A. Myers, David Mcgrath, Ruth M. O'riordan, Jane DelanyAbstract:Areas which were under the influence of runoff seeping slowly from upshore rockpools were identified at two shores in Co. Cork, Ireland. Surveys of adult and 0+Chthamalus stellatus and C. montagui were carried out in these areas and compared with adjacent dry areas. A second survey on cleared quadrats examined barnacle abundance in wet and in dry areas at 1 and 5 months after the initiation of settlement. Chthamalus stellatus adults and 0+ individuals were significantly more abundant in wet areas than in dry areas, which in the context of previous laboratory findings suggest that desiccation or some other parameter associated with wetness may be an important factor in limiting the vertical distribution of this species. Chthamalus montagui adults and 0+ individuals were significantly more abundant in dry areas than in wet areas. The lower vertical limit of this species may therefore also be set by some wetness parameter. In 1 month and 5 month old stages, the differences in abundance between wet and dry conditions were apparent in both species but were only significant in both age classes of C. montagui at one of the study shores. The results are discussed in the context of vertical and geographical distribution patterns exhibited by adults of each species on European shores.
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Prolonged settlement and prediction of recruitment in two sympatric intertidal Chthamalus species from south-west Ireland
Journal of the Marine Biological Association of the United Kingdom, 1999Co-Authors: Anne Marie Power, Jane Delany, Alan A. Myers, Ruth M. O'riordan, David McgrathAbstract:Attached cypris larvae and less than one month old metamorphs of Chthamalus stellatus and C. montagui (Crustacea: Cirripedia) were sampled from random quadrats on two shores in County Cork, Ireland, from July 1996 to June 1997. Cyprids of C. stellatus were much more abundant than those of C. montagui , but the relative abundance of metamorphs of the two species did not differ significantly. Cyprid abundance predicted metamorph recruitment intensity during peak settlement in C. stellatus but not in C. montagui .
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The sizes at settlement in natural populations of the cyprids of Chthamalus montagui and C. stellatus
Journal of the Marine Biological Association of the United Kingdom, 1999Co-Authors: Ruth M. O'riordan, Jane Delany, David Mcgrath, Alan A. Myers, Anne Marie PowerAbstract:The lengths of chthamalid cyprids collected during August 1996 on six rocky shores in County Cork, Ireland are reported. The lengths showed a bimodal distribution. The smaller length mode corresponded well with the length range of laboratory-reared cyprids of Chthamalus montagui (Crustacea: Cirripedia), whilst the larger length mode was greater than the length range reported for laboratory-reared C. stellatus . Size may be a useful means to identify Chthamalus cyprids in field investigations.