Chthamalus Fissus Research Articles

Periodicity in Chthamalus fissus reproduction does not guarantee periodicity in settlement

The timing of life history events can have profound implications for populations and communities, especially those events that influence species dispersal and recruitment. In benthic invertebrates, the majority of dispersal occurs during the larval phase of life. Yet the extent to which timing of reproduction (the beginning of the larval phase) directly influences timing of settlement (the end of the larval phase) is unclear, because biological and hydrodynamic processes can act to decouple these 2 events, and because reproduction and settlement are seldom studied together. Here, we used long-term (2014-2019) daily and weekly data from Bird Rock, La Jolla, California, USA, to look for lunar and seasonal cycles in reproduction and settlement timing of the acorn barnacle Chthamalus fissus, and we incorporated measurements of nearshore currents to examine the implications of reproduction timing on alongshore larval transport distances. We found evidence of lunar and seasonal cycles in reproduction but only limited cyclicality in settlement, possibly due to plasticity in larval development coupled with variable larval transport and dispersal. Our results demonstrate the complex nature of relationships between reproduction, larval transport, and settlement, which must be disentangled before accurate predictions can be made regarding the impacts of climate change on the population dynamics of marine species.

Diversity and distribution of nearshore barnacle cyprids in southern California through the 2015-16 El Niño.

Abundance, species diversity, and horizontal distributions of barnacle cyprids offshore of La Jolla, southern California were described from May 2014 to August 2016 to determine how the nearshore barnacle larval assemblage changed before, during, and after the 2015–16 El Niño. The entire water column was sampled at five stations located within one km of shore with water depths of 4, 6, 8, 10, and 12 m during 33 cruises that encompassed the time when El Niño conditions impacted the area. Nearshore temperature and thermal stratification was concurrently measured using a CTD. Six identified cyprid species, including Chthamalus fissus, Pollicipes polymerus, Megabalanus rosa, Tetraclita rubescens, Balanus glandula, and B. trigonus, along with four unknown species, were collected in our samples. DNA barcoding was used to confirm identifications in a subset of the larvae. C. fissus was more than eight times more abundant than any other species, and while abundance varied by species, cyprid density was highest for all species except for M. rosa before and after the El Niño event, and lower during the environmental disturbance. There were significant differences in cross-shore distributions among cyprid species, with some located farther offshore than others, along with variability in cross-shore distributions by season. C. fissus cyprids were closest to shore during spring-summer cruises when waters were the most thermally stratified, which supports previous findings that C. fissus cyprids are constrained nearshore when thermal stratification is high. Relative species proportions varied throughout the study, but there was no obvious change in species assemblage or richness associated with El Niño. We speculate that barnacle cyprid species diversity did not increase at our study site during the 2015–16 El Niño, as it has in other areas during previous El Niño Southern Oscillation events, due to the lack of anomalous northward flow throughout the 2015–16 event.

Parasite and host biomass and reproductive output in barnacle populations in the rocky intertidal zone.

The rocky intertidal zone has a long history of ecological study with barnacles frequently serving as a model system to explore foundational theories. Parasites are often ignored in community ecology studies, and this particularly holds for true for the rocky intertidal zone. We explore the role of the isopod parasite, Hemioniscus balani, on its host, the acorn barnacle, Chthamalus fissus. We use the currencies of biomass and reproduction measured at the individual level, then applied to the population level, to evaluate the importance of this parasite to barnacle populations. We found H. balani can comprise substantial biomass in 'apparent' barnacle populations, sometimes even equaling barnacle biomass. Additionally, parasite reproduction sometimes matched barnacle reproduction. Thus, parasites divert substantial energy flow from the barnacle population and to near-shore communities in the form of parasite larvae. Parasites appeared to decrease barnacle reproduction per area. Potentially, this parasite may control barnacle populations, depending on the extent to which heavily infected barnacle populations contribute to barnacle populations at larger scales. These findings regarding the importance of a particular parasite for host population dynamics in this well studied ecosystem call for the integration of disease dynamics into community ecological studies of the rocky intertidal zone.

Specificity and costs of inducible defense in the barnacle Chthamalus fissus (Darwin, 1854)

Specificity and costs of inducible defense in the barnacle Chthamalus fissus (Darwin, 1854)

Reduced barnacle larval abundance and settlement in response to large‐scale oceanic disturbances: Temporal patterns, nearshore thermal stratification, and potential mechanisms

AbstractWe assessed the effects of large‐scale oceanic disturbances on the settlement rate of an abundant intertidal barnacle. Daily or weekly settlement, nearshore temperature, currents, and abundance of early‐stage barnacle nauplii and Chthamalus fissus cyprids were measured in La Jolla, California, from the inception of the large‐scale warm‐water anomaly known as the “Blob” in 2014, to 1 yr following the 2015/2016 El Niño. We also measured over 2 yr of weekly settlement rates during the 1997/1998 El Niño in La Jolla and in two Mexican sites. Settlement was low during the Blob and the 2015/2016 El Niño, but increased dramatically after its end, and rates remained high through spring 2017. Barnacle nauplii and C. fissus cyprid abundances were also low during the Blob and El Niño. Nearshore water column thermal stratification and variability of the high‐frequency cross‐shore currents, a measure of internal wave activity, declined during the Blob and El Niño, but increased at the end of El Niño. Similarly, settlement rates in the Mexican sites were low during the 1997/1998 El Niño. The reduction in settlement during the Blob and El Niño may be related to two factors: a decrease in water column stratification, which can influence internal bore larval transport and the cross‐shore distribution of larvae, and also to reduced early‐stage larval abundance, potentially related to lower reproductive output or high nauplii mortality during the disturbances.

Constrained nearshore larval distributions and thermal stratification

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 595:105-122 (2018) - DOI: https://doi.org/10.3354/meps12561 Constrained nearshore larval distributions and thermal stratification Malloree L. Hagerty1,*, Nathalie Reyns1, Jesús Pineda2 1Environmental and Ocean Sciences Department, University of San Diego, San Diego, California 92110, USA 2Biology Department, Woods Hole Oceanographic Institution, Woods Hole, Massachusetts 02543, USA *Corresponding author: mhagerty@sandiego.edu ABSTRACT: Vertical and cross-shore distributions and abundances of shallow-water barnacle larvae were characterized in La Jolla, southern California (USA), during a 2 yr period. Five stations located within 1 km of shore and ranging from 4-12 m water depths were sampled intensively in 2 m depth intervals during 27 cruises throughout spring-summer (April-July) and fall-winter (October-December) of 2014 and 2015. Larval abundances significantly decreased from 2014 to 2015, which could be related to the arrival of a warm-water anomaly (the so-called ‘Blob’) in 2014 and El Niño conditions in 2015. Despite the presence of these large-scale regional disturbances, vertical and cross-shore larval distributions were consistent throughout the 2 yr study period. Early-stage nauplii and Chthamalus fissus cyprids tracked bottom depth, and cyprids were on average deeper than nauplii. Vertical distributions were not related to the mid-depth of the thermocline or thermal stratification. Early-stage nauplii had a broader cross-shore distribution than cyprids, which were concentrated at inshore stations. Nearshore cyprid concentration had a positive relationship with thermal stratification, and the center of distribution of cyprids was farther offshore during fall-winter when stratification decreased. These results suggest that thermal stratification elicits enhanced behavioral control of cyprids to remain close to shore and reach the adult habitat. KEY WORDS: Barnacle larvae · Chthamalus fissus · Early-stage nauplii · Cyprids · Hydrographic and hydrodynamic conditions Full text in pdf format Corrigendum PreviousNextCite this article as: Hagerty ML, Reyns N, Pineda J (2018) Constrained nearshore larval distributions and thermal stratification. Mar Ecol Prog Ser 595:105-122. https://doi.org/10.3354/meps12561 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 595. Online publication date: May 14, 2018 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2018 Inter-Research.

High density and strong aggregation do not increase prevalence of the isopod Hemioniscus balani (Buchholz, 1866), a parasite of the acorn barnacle Chthamalus fissus (Darwin, 1854) in California

Parasitism is a common life history strategy among animals and has been the topic of empirical and theoretical study for decades. Many classic mathematical models assume increased spatial aggregation and density increase prevalence in a host population. Parasites can nevertheless take on a diversity of life history strategies that could result in deviations from these assumptions. I investigated the importance of density and aggregation of hosts on the prevalence, or percent of hosts infected by a parasitic castrator with a complex life cycle. An isopod parasite, Hemioniscus balani (Buchholz, 1866), infects an intertidal barnacle, Chthamalus fissus (Darwin, 1854), and renders the barnacle unable to produce eggs. To test the assumptions that density and aggregation increase parasitism, I conducted a survey of density, aggregation, and parasitism in the rocky intertidal zone in Santa Barbara County, CA, USA. I found spatial patterns of host density and aggregation did not lead to increases in parasitism. Furthermore, there was no evidence of a selfish herd effect, whereby the per capita risk of infection decreases with population size. Understanding patterns and drivers of infection is particularly important in marine systems, which are understudied compared to terrestrial diseases, and work done in terrestrial systems could not correspond to patterns and processes in marine systems.

Historical and recent processes shaping the geographic range of a rocky intertidal gastropod: phylogeography, ecology, and habitat availability.

Factors shaping the geographic range of a species can be identified when phylogeographic patterns are combined with data on contemporary and historical geographic distribution, range-wide abundance, habitat/food availability, and through comparisons with codistributed taxa. Here, we evaluate range dynamism and phylogeography of the rocky intertidal gastropod Mexacanthina lugubris lugubris across its geographic range – the Pacific coast of the Baja peninsula and southern California. We sequenced mitochondrial DNA (CO1) from ten populations and compliment these data with museum records, habitat availability and range-wide field surveys of the distribution and abundance of M. l. lugubris and its primary prey (the barnacle Chthamalus fissus). The geographic range of M. l. lugubris can be characterized by three different events in its history: an old sundering in the mid-peninsular region of Baja (∼ 417,000 years ago) and more recent northern range expansion and southern range contraction. The mid-peninsular break is shared with many terrestrial and marine species, although M. l. lugubris represents the first mollusc to show it. This common break is often attributed to a hypothesized ancient seaway bisecting the peninsula, but for M. l. lugubris it may result from large habitat gaps in the southern clade. Northern clade populations, particularly near the historical northern limit (prior to the 1970s), have high local abundances and reside in a region with plentiful food and habitat – which makes its northern range conducive to expansion. The observed southern range contraction may result from the opposite scenario, with little food or habitat nearby. Our study highlights the importance of taking an integrative approach to understanding the processes that shape the geographic range of a species via combining range-wide phylogeography data with temporal geographic distributions and spatial patterns of habitat/food availability.

Predator-Induced Defense in the Barnacle Chthamalus Fissus

Inducible defenses are phenotypically plastic traits in which individuals or colonies develop a predator/herbivore-resistant trait in response to a cue. The barnacle Chthamalus fissus, commonly found in the upper intertidal of southern California and Baja California, Mexico, exhibits three morphs: one with an oval operculum, one with a narrow, slit-like operculum, and a relatively uncommon bent form with the operculum opening on one side. A previous study suggested that the narrow and bent morphs are defended from attack by the predatory snail Mexcanthina lugubris lugubris. In the present study, predator exposure and predator exclusion experiments revealed that operculum morphology of C. fissus is a plastic trait: individuals exposed to M. lugubris lugubris develop into the narrow operculum morph or, less commonly, the bent morph. While some species of marine invertebrates exhibit either a generalized plasticity response to various predators or plastic traits that are specific to the type of predator to which they have been exposed, the observation in this study appears to be the first demonstration of the occurrence of alternative inducible defenses to the same predator within a single species of marine invertebrate.

Inter-Population Variation in Shell Morphology of the Barnacle Chthamalus Fissus

Phenotypic traits often differ among conspecific populations inhabiting different environments. These morphological types may represent unique genotypes that are best suited to local conditions, or they may result from individual responses to local environmental conditions and thus represent plastic phenotypes. The barnacle Chthamalus fissus, commonly found in the upper intertidal of southern California and Baja California, Mexico, exhibits three morphs: one with an oval operculum, one with a narrow, slit-like operculum, and a relatively uncommon bent form with the operculum opening on one side. The aim of this study was to determine if differences in shell morphology among two populations of C. fissus separated by approximately 100 km result from local adaptation or are the result of plasticity in development of the barnacle shell. A reciprocal transplant experiment was conducted in which rocks with attached juvenile barnacles were transferred among populations from La Jolla, California, USA, where adults exhibit an oval operculum, and Ensenada, Baja California, Mexico, where adults exhibit either a narrow operculum or the bent morphology. The results indicate that barnacle morphology is determined by local conditions and is not due to genetic differences between the two populations. Results of a field experiment examining predation by the snail Mexacanthina lugubris lugubris suggest that oval morphs are more vulnerable than narrow morphs to this predator. Environmental factors that may be responsible for inducing this morphological variation are discussed.

Systematics and biogeography of Tropical Eastern Pacific Chthamalus with descriptions of two new species (Cirripedia, Thoracica)

Distribution patterns of Chthamalus along the Tropical Eastern Pacific region have not yet been described, mostly due to unknown species ranges and the presence of cryptic species that has biased previous attempts to describe them. Prior to this paper, four formal and two informal species of Chthamalus have been recognized as occurring along the Pacific Americas coast: C. dalli Pilsbry; C. fissus Darwin; C. anisopoma Pilsbry; C. panamensis Pilsbry, Chthamalus sp. “cortezianus” and Chthamalus sp. “mexicanus”. The two informal species were already known to exist, based on previous studies using allozymes and gene sequencing, but their morphological characterizations were not determined, thus preventing their recognition and the ascertainment of their status under the International code of Zoological Nomenclature. The main goal of the present study was to discover the morphological differences that distinguish these two species, to determine their latitudinal range, to establish some relationship among the other species of Chthamalus, and to correlate these with the informal names previously used. Two new species of Chthamalus are described: C. hedgecocki sp. nov. occurring along the Mexican coast (Mexican province) and Chthamalus southwardorum sp. nov. occurring from the Gulf of California (Mexico) to the north of Peru, being a typical member of Panamanian s. l. Province. Both species belong to the Chthamalus fissus group of species as they have bidenticulate setae with basal guards on cirrus II and an absence of conical spines on the outer face of the exopod of cirrus I. The names Chthamalus sp. “cortezianus” is herein associated with C. hedgecocki and Chthamalus sp. “mexicanus” with C. southwardorum. An extensive sympatric distribution of Chthamalus species was noticed along the Eastern Pacific, and Chthamalus panamensis, previously known to be limited to the Panamanian coast, was found up to the Mexican coast in sympatry with C. hedgecocki. The COI genetic divergence between C. panamensis and C. hedgecocki varied between 2.8–4.3 using (GTR+G). We suggest that these species form a sibling pair based on to their morphological, ecological and genetic similarities and their evolution took place along the Eastern Pacific coast after the closure of the Isthmus of Panama. Chthamalus southwardorum is the best choice for a sibling pair with C. proteus, as they share morphological and ecological features; nevertheless they present a very high genetic divergence (24.3 to 25.1 GTR+G). Further studies are needed to clarify the evolutionary processes that led to the evolution of the Chthamalus fissus group of species along the Tropical Eastern Pacific coast and in the Caribbean.

Reliability of Multitaxon, Multiproxy Reconstructions of Environmental Conditions from Accretionary Biogenic Skeletons

Abstract Evaluation and quantification of climate change require data on subseasonal to daily environmental extremes from those periods before instrumental records were available. This study employs a high‐resolution, multitaxon, multiproxy approach and analyzes how faithfully accretionary biogenic skeletons record environmental extremes. Six specimens of two bivalve mollusks (Chione fluctifraga, Mytella guyanensi) and one barnacle species (Chthamalus fissus) from a single habitat (northern Gulf of California, Mexico) were collected. Contemporaneous shell portions from these specimens were analyzed for shell growth rates (sclerochronology) and stable isotopes (δ18O, δ13C) and were compared to instrumental records. The results of these analyses included some significant observations. First, shell δ18O values overestimate winter temperatures and underestimate summer temperatures. Second, the actual diurnal temperature range is not recorded in the biogenic skeletons. Third, skeletal growth is biased toward a...

Geographic range in Chthamalus along the west coast of North America

Identification of the range boundaries and microgeographic distribution of cryptic species is greatly facilitated by the use of genetic markers. Here we characterize the geographic range overlap between two cryptic species, Chthamalus fissus and C. dalli, and show that as with other barnacle species, their distribution and abundance is probably dictated more by microhabitat characteristics and the presence of conspecifics than broader environmental gradients. We also show that C. dalli appears to be panmictic across the studied range.

Modelling the effects of an oil spill on open populations of intertidal invertebrates

Summary Knowledge of the impact of oil spills on coastal communities, in California and elsewhere, is currently limited by a lack of long‐term data, the inability to infer causality from monitoring studies, and the necessarily limited spatial and temporal scales of experimental studies. This study therefore used a modelling approach to investigate the combined effects of different intensities of an oil spill and recruitment variation on a barnacle Chthamalus fissus population. The methodology and results are likely to apply to any similarly open marine populations with dispersive larval forms. The model consisted of a source population comprising individuals that reproduced based on size and probability of mortality. Larvae from the source population entered a larval pool. A proportion of the larvae from the larval pool recruited to a focal population within the region. The model was used to assess the effects on recruitment to the focal population of (i) the size structure of the source population, (ii) the intensity of oil spills in the source population, and (iii) recruitment intensity to the focal population. Differences in the size structure of the source population had little effect on the reproductive output of the population relative to the intensity of the oil spill. Similarly, the intensity of the oil spill had a stronger influence on recruitment to the focal population than the size structure of the source population. Size structure of the source population was important, however, when evaluating the seasonal trajectory of the focal population. Modelling provides a format in which questions about the effects of human impacts can be addressed that would be intractable using experiments. The results of this model suggest that recruitment variation, along with the processes underlying recruitment variation, are critical to predicting the effects of disturbance on open marine populations.

DESCRIPTIONS OF THE LARVAE OF TETRACLITA RUBESCENS AND MEGABALANUS CALIFORNICUS WITH A COMPARISON OF THE COMMON BARNACLE LARVAE OF THE CENTRAL CALIFORNIA COAST

ABSTRACT The larvae of Tetraclita rubescens and Megabalanus californicus are described for the first time. In addition, comparisons are made with other common, mostly intertidal, barnacle species on the central California coast, including Chthamalus dalli, Chthamalus fissus, Pollicipes polymerus, Balanus glandula, Balanus crenatus, Balanus nubilus, Balanus improvisus, Balanus amphitrite amphitrite, and Semibalanus cariosus. Differences in size, setation of appendages, and body forms are used to distinguish species and larval stages.

Recruitment Regulates Demographic Variation in a Tropical Intertidal Barnacle

I studied populations of the barnacle Chthamalus fissus on the central Pacific coast of Costa Rica to determine the relative importance of pre— and post—settlement processes in determining patterns of distribution and abundance. Populations were studied at 10 sites representing five different microhabitats on one shore. Sites were censused photographically from 1983 to 1985 at 1—3 mo intervals, yielding data on recruitment, growth, and mortality. Mortality after settlement (=after day 1) was density independent for at least 90 d, so recruitment reflected settlement. Abundance appeared limited by sparse recruitment since considerable bare space was available at most sites during much of the study. Intraspecific competition (preemptive and adult—adult) was weak, except after occasional peaks of dense recruitment. Interspecific interactions were also weak, except for localized, intense predation by the thaidid gastropod Acanthina brevidentata near cracks and crevices, and sporadic competition with the small mussel Brachidontes semilaevis. In large part, demography of C. fissus was regulated by events in the water column affecting settlement and subsequent recruitment. Similar communities are found on rocky shores in the Bay of Panama, in central Costa Rica, and in the northern Gulf of California. Recruitment of Chthamalus spp. is very sparse in the Bay of Panama, sparse with occasional peaks in central Costa Rica, and consistently dense in the northern Gulf of California. Post—settlement processes involving Chthamalus spp. (competition and predation) appear strong and pervasive only in the northern Gulf of California. Abundance of Chthamalus fissus in Central America is regulated by events in the water column that determine the number of cyprids arriving to the substratum, an example of supply—side ecology.

Comparison of Larval and Adult Stages of Chthamalus dalli and Chthamalus fissus (Cirripedia: Thoracica)

Comparison of Larval and Adult Stages of Chthamalus dalli and Chthamalus fissus (Cirripedia: Thoracica)

COMPARISON OF LARVAL AND ADULT STAGES OF CHTHAMALUS DALLI AND CHTHAMALUS FISSUS (CIRRIPEDIA: THORACICA)

ABSTRACT Adult and larval forms of Chthamalus dalli and Chthamalus fissus are compared and distinguishing characteristics described. Adult forms of these species differ in malate dehydrogenase enzyme allozymes, in the setae of the second cirrus, and in shell characteristics. Larval forms are morphologically identical, although larvae cultured from adults collected at Monterey Bay differ in size at naupliar stages I-III and at the cyprid stage.

Parasitic castration: host species preferences, size-selectivity and spatial heterogeneity.

This study investigates host-parasite population dynamics in a marine intertidal community of three barnacle host species (Balanus glandula, Chthamalus fissus andC. dalli). Our paper addresses the following questions: (1) Does prevalence (percentage parasitism) differ among the three host species? (2) What are the spatial and temporal population dynamics within the community? and (3) Does the parasite exhibit size-selective behaviour in any of the three host species? Significant differences in prevalence were found among the three host species; the parasitic castrator (Hemioniscus balani) most heavily infected the least abundant host. Parasitism occurred throughout the year and also showed significant spatial variation.H. balani showed size-selective parasitism inC. fissus, but not inC. dalli. Consequently, the population effects of parasitic castration inC. fissus depend both upon the host population size structure and the intensity of the parasite's size-selectivity.

Habitat segregation and temporal variation in some tropical intertidal populations

Observations were made to document habitat segregation and seasonal changes in density for the most common intertidal organisms at a study site on the Pacific coast of Costa Rica. The pulmonate limpets Siphonaria gigas (Sowerby) and Siphonaria maura (Sowerby) were more abundant in the mid-high- and high-intertidal zone, whereas the keyhole limpet Fissurella virescens (Sowerby) was more abundant in the mid zone. Coiled gastropods were found in the mid- and mid-high-intertidal zone but were absent or scarce in the high zone. Barnacles and coralline algae were found throughout the intertidal zone and foliose algae were mostly present in the splash zone. Abundance of all species changed over the 2-yr period of the study. S. gigas and S. maura and the barnacle Chthamalus fissus Darwin exhibited well-defined fluctuations in density related to recruitment. No recruitment was observed for F. virescens or Tetraclita panamensis Pilsbry and populations of both species declined. Changes also occurred for coiled gastropods and were probably related to movement of adults. Coralline and foliose algae were more abundant during the rainy season than during the dry months. Far from being constant, populations on these tropical shores were highly dynamic with temporal changes rivaling those in the temperate zone.