DSpace Angular :: Browsing by Author "Castilla, JC"

Browsing by Author "Castilla, JC"

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A biochemical study of the larval and postlarval stages of the Chilean scallop Argopecten purpuratus
(1998) Farias, A; Uriarte, I; Castilla, JC
Eggs, larvae and postlarvae of northern scallop, Argopecten purpuratus, were collected from the experimental hatchery of the Estacion Costera de Investigaciones Marinas (ECIM) of the Pontificia Universidad Catolica de Chile at Las Cruces to compare their protein, lipid and carbohydrate composition. In the egg protein, lipid and carbohydrate accounted for 38.2, 34.1 and 1.5% ash-free dry weight (AFDW), respectively. Protein in the larvae increased from 43.9 to 55.9% AFDW throughout larval development, and after metamorphosis values varied between 39.8 and 62.1% AFDW, with highest values in 22 day-old postlarvae. Lipids were constant at 20% AFDW during larval development, decreasing to 7.4% AFDW in the premetamorphosis period and increasing again to a constant value of 15% AFDW during the 22 days after metamorphosis, then decreasing to 2.5% AFDW. Carbohydrate contents were lower than lipid and protein in all larval stages, varying between 5.1 and 16.5% AFDW; during the postmetamorphosis period, carbohydrate content varied between 6.6 and 14.4%, but they were higher than lipid by day 60 after metamorphosis. The premetamorphosis period was characterized by a considerable decrease in lipid accompanied by a small decrease in protein and carbohydrate. The planting-out stage (commercial seed) was characterized by a high content of protein and a reduced content of lipid in relation to carbohydrate. This work provides basic information on the role played by the balance of energy reserves in the metabolism of scallop larvae. (C) 1998 Elsevier Science B.V. All rights reserved.
An assessment of the potential use of the nematode to copepod ratio in the monitoring of metals pollution. The Chanaral case
(2001) Lee, MR; Correa, JA; Castilla, JC
We discuss the use of the nematode to copepod ratio in relation to determining the extent of metals impact using the Chanaral area of northern Chile, where the dumping of copper mine tailings has taken place for many years, as an example. Data were collected from 12 beaches in the area on eight occasions between January 1997 and October 1998. We find that the ratio is not a good predictor of pollution due to the generally low densities of meiofauna on impacted beaches and the absence of harpacticoid copepods from those beaches. We suggest that in the case of metal pollution the mean number of Harpacticoida per site may be a better indicator of impact stress. We rule out the use of the nematode to copepod ratio as an indicator in biomonitoring studies where metal enrichment is thought to occur. (C) 2001 Elsevier Science Ltd. All rights reserved.
Avoiding offshore transport of competent larvae during upwelling events
(2002) Poulin, E; Palma, AT; Leiva, G; Narvaez, D; Pacheco, R; Navarrete, SA; Castilla, JC
The coast of central Chile is characterized by the occurrence of coastal upwelling during the austral spring and summer seasons, which probably has important consequences for the cross-shelf transport of larval stages of many species. Three cruises were conducted off the locality of El Quisco during upwelling-favorable wind periods to determine the surface distribution of epineustonic competent larvae of the gastropod Concholepas concholepas during such events. Contrary to the predictions of a traditional model, where neustonic-type larvae are transported offshore under such conditions, competent larvae of this species were exclusively found in the area between the shore and the upwelling front. Two additional cruises were conducted during calm periods to determine diel variation in the vertical distribution of C. concholepas competent larvae. The absence of competent larvae at the surface during early night hours suggests a reverse vertical migration. Thus, the retention of C. concholepos competent larvae in the upwelled waters could be the result of the interaction between their reverse diel vertical migration and the typical two-layer upwelling dynamics.
Distribution, population structure, population biomass and morphological characteristics of the tunicate Pyura stolonifera in the Bay of Antofagasta, Chile
(2000) Castilla, JC; Guiñez, R; Alvarado, JL; Pacheco, C; Varas, M
The present study analyzes the distribution, population structure, population biomass and morphological characteristics of the intertidal tunicate Pyura stolonifera (Heller, 1878) in the Bay of Antofagasta, Chile, where the species shows a reduced geographical range extending around 60-70 km. Three sites along its distribution were studied. At the central site the tunicate presents the widest intertidal belts, reaching nearly 11 m (the mid-intertidal-Pyura-zone shows the higher percent cover). Population dry biomass here averaged up to 20.45 kg.m(-2), representing one of the highest intertidal specific biomasses reported in the literature. Lower values occur towards the borders of its distribution. Population densities were over 1800 indiv..m(-2) at mid-intertidal-Pyura-belts. Crowding and competition potentially affect morphological characteristics and the energy/tissue allocation along the intertidal and geographical gradient of P. stolonifera.
Does early development of the Chilean tunicate Pyura praeputialis (Heller, 1878) explain the restricted distribution of the species?
(1999) Clarke, M; Ortiz, V; Castilla, JC
Relationships between the rate of larval development and dispersal of a species can have a large influence on observed patterns of its distribution and abundance. Distribution patterns of the dense belt-forming rocky intertidal ascidians Pyura praeputialis and Il stolonifera (Urochordata: Ascidiacea: Pyuridae) show drastic differences. II stolonifera extends along the coast of South Africa for 1000s of kilometers and I? praeputialis shows a similar range in Australia (New South Wales, Victoria and Tasmania). On the contrary, in Chile I! praeputialis is characterized by a population which occurs along less than 70 km of coastline in and around the Bay of Antofagasta. The larval and development characteristics of the South African and Australian species have been studied while those of the population from Chile has not been described. This study describes the early embryology and larval development of the Chilean species and shows that the development times and the free-swimming larval stage of I? praeputialis in Chile and Australia are similar. Therefore, it is suggested that the differences in the extension of their range of distribution in Australia and Chile cannot be accounted for due to differences in the developmental biology, but it may be due to a recent invasion of the species to Chile. Comparison between the development biology of P. praeputialis and II chilensis are also made.
Effect of antibiotic treatment during larval development of the Chilean scallop Argopecten purpuratus
(2001) Uriarte, I; Farías, A; Castilla, JC
The requirement for antibiotic use in a culture depends principally on the quality of water available and on the use of strict husbandry of the materials closely related with the culture. The purpose of the present study was to determine the dose of chloramphenicol resulting in better survival and growth rates of Chilean scallops between the early larvae and pediveliger stages cultured in closed systems with manual dosing of food two times per day. Two experiments with antibiotic application during larval development of the Chilean scallop (Argopecten purpuratus) were conducted. The experiments were carried out at the early larval stage (86 mum) and at the eyed stage (213 mum). The antibiotic concentration ranged between 0 and 8 mg l(-1) chloramphenicol (CHL) per day. The survival and growth rates of the larvae were monitored for 10 days at each stage. In the experiment with eyed larvae, larval settlement and percent metamorphosis were measured. Use of an antibiotic on the early larvae resulted in significantly better growth and survival. Growth rates were 2.3 +/- 0.3 and 2.6 +/- 0.2% per day when using 2 and 8 mg l(-1) CHL per day, respectively, compared with 1.3% +/- 0.2 per day for the larvae without antibiotic. Survival was also better with antibiotic treatment reaching 50% compared with 35% without antibiotic. The metamorphosis was highest using of 8 mg l(-1) CHL day(-1), compared with treatment without antibiotic. Between 75 and 79% of the metamorphosed larvae were found settled on the nets in the treatments using 2 and 8 mg l(-1), while only 55.5% were settled in the nets in the treatment without antibiotic. The results of the experiments indicate that concentrations of 2 and 8 mg l(-1) CHL demonstrated effective control of larval contamination. Moreover, the condition of the postlarvae was improved by the addition of 8 mg l(-1) CHL from eyed larvae to postlarvae. (C) 2001 Elsevier Science B.V. All rights reserved.
Effects of experience and risk of predation on the foraging behaviour of the South-eastern Pacific muricid Concholepas concholepas (Mollusca: Gastropoda)
(1997) Serra, G; Chelazzi, G; Castilla, JC
1. Different size classes of the muricid Concholepas concholepas (Bruguiere)(small and medium subadult specimens inhabiting mainly the high-and mid-intertidal, and large adult ones inhabiting mainly the subtidal) were assessed for handling times and diet selection by offering them three different sizes of the high-intertidal mussel Perumytilus purpuratus (Lamarck).
Foraging behavior of the American oystercatcher Haematopus palliatus pitanay (Murphy 1925) on the intertidal ascidian Pyura praeputialis (Heller 1878) in the Bay of Antofagasta, Chile
(2001) Pacheco, CJ; Castilla, JC
Oystercatcher foraging behavior has been described for diverse intertidal prey such as limpets, mussels, and oysters. This paper describes foraging behavior of the American oystercatcher, Haematopous palliatus pitanay, on attached and wave-dislodged ascidians, Pyura praeputialis (prey with a restricted geographic range of 70 km) in the Bay of Antofagasta, Chile. Stabbed holes on the top of the ascidian's tunic, probing excursions, handling time, and five prey-handling sequential stages (striking, hammering, prying, cavity food searching, and swallowing) are described and measured. The need to determine ascidian profitability for oystercatcher species in Australia and Chile is highlighted.
Harvesting and economic patterns in the artisanal Octopus mimus (Cephalopoda) fishery in a northern Chile cove
(1998) Defeo, O; Castilla, JC
We analyze intra- and inter-annual harvesting and economic patterns of the cephalopod Octopus mimus (pulpo) artisanal fishery at Caleta Coloso cove, Antofagasta, northern Chile, between 1991 and 1996. Information was collected daily, from 25 hookah divers that manually harvest pulpo in the subtidal along 29 km of coastline. Inter-annual fluctuations in catch, fishing effort, unit price and economic revenues increased from 1993 to 1996, when O. mimus landing and total revenues at Coloso were over 77 t and US$ 190 000, respectively. Contrary to the observed annual trend, the inverse intra-annual correlation between catch/fishing effort and price indicated short-term changes in price according to resource availability. A monotonic decreasing function between CPUE and price suggested a threshold catch rate economically feasible for harvesting. Interannual changes in the slope of the price-CPUE function indicated a marked increase in the demand of pulpo, jointly with warnings of stock depletion. We conclude that the 0. mimus temporal fishery patterns at Coloso are scale-dependent. Our results and general fishery patterns in the Chilean pulpo fishery suggest that a precautionary management scheme is urgently needed to prevent overfishing. (C) 1998 Elsevier Science B.V. All rights reserved.
Influence of coastal upwelling and El Nino-Southern Oscillation on nearshore water along Baja California and Chile
(2004) Takesue, RK; van Geen, A; Carriquiry, JD; Ortiz, E; Godínez-Orta, L; Granados, I; Saldívar, M; Ortlieb, L; Escribano, R; Guzman, N; Castilla, JC; Varas, M; Salamanca, M; Figueroa, C
[ 1] In order to determine the sensitivity of coastal upwelling tracers to seasonal wind forcing and El Nino-Southern Oscillation (ENSO) off Baja California and Chile, nearshore salinity, cadmium (Cd), and nutrients phosphate, silicate, nitrate+ nitrite were monitored in surf zone waters at six locations along the North and South American coasts during 1997-2000. The clearest responses to upwelling favorable wind forcing were observed at the southern tip of Baja California (23.3degreesN) and off central- southern Chile (36.5degreesS). Upwelling tracers at 23.3degrees N were also the most sensitive to El Nino: average summer Cd and nutrient enrichments were 60% lower following El Nino than during the previous non-El Nino upwelling season. At two sites on the northern and central Chile coasts, conditions associated with El Nino resulted in salinity anomalies >1. Such large shifts in nearshore water properties suggest it may be possible to reconstruct past ENSO patterns from geochemical paleonutrient/paleosalinity proxy records preserved in nearshore archives such as mollusc or foraminifera shells.
Invasion of a rocky intertidal shore by the tunicate Pyura praeputialis in the Bay of Antofagasta, Chile
(2004) Castilla, JC; Guiñez, R; Caro, AU; Ortiz, V
Invasion by marine nonindigenous species (NIS) is a spread phenomenon. The tunicate Pyura praeputialis shows pronounced disjoint geographical distribution: along thousands of kilometers in wave-swept headlands on the southeastern coast of Australia, from where it appears to have originated, and exclusively along 60-70 km inside the Bay of Antofagasta, Chile. mtDNA sequences suggested that the species invaded this rocky shore recently. We used field manipulations and juvenile A praeputialis transplant techniques to test hypotheses regarding the capacity of the tunicate to survive and grow at different sites and tidal heights inside and outside Antofagasta, and its competitive performance for primary space (inside the Bay) against the native mussel Perumytilus purpuratus. We conclude that survival and growth of A praeputialis showed no significant differences among sites inside and outside the Bay, and suggest that the restrictive distribution of the species in Chile is caused by a specific oceanographic retention mechanism and/or its brief larval dispersal. We demonstrated that, inside the Bay, P. praeputialis outcompetes Perumytilus from the Mid-Low intertidal, constraining Perumytilus to the Upper Mid-Intertidal, modifying the local pattern of intertidal zonation. We show that predation on P. praeputialis juveniles by starfish and snails constitutes a regulatory mechanism for the setting of its low intertidal limit. Major ecological impacts caused by NIS invasions to rocky shores by aggressive primary space users may result in negative aspects, but also may contribute to biodiversity enhancement. We call attention to the need for increment manipulations and testing of ecological hypotheses regarding marine NIS.
Latitudinal variation in the reproductive biology of the commensal crab Pinnaxodes chilensis (Decapoda: Pinnotheridae) along the Chilean coast
(2001) Lardies, MA; Castilla, JC
The pinnotherid crab Pinnaxodes chilensis is a common commensal of the edible sea urchin Loxechinus albus along the Chilean coast. Several aspects of the reproductive biology of P. chilensis were examined between April and June 1999, along temperature and salinity gradients, at three sampling sites along the Chilean coast (23degrees45'S-39degrees24'S). Results demonstrated significant differences in egg number, egg volume, dry egg weight, and reproductive output of ovigerous females, between the Studied populations of northern and central-southern Chile. Egg volume, egg dry weight, and reproductive output of females decreased from high to low latitudes, while egg number increased from high to low latitudes, exhibiting a clear trade-off with egg volume. It has been shown that changes in environmental conditions (e.g. temperature, salinity) along a latitudinal gradient, can generate clines in reproductive characteristics in both free-living and parasitic species.
Marine ecosystem engineering by the alien ascidian Pyura praeputialis on a mid-intertidal rocky shore
(2004) Castilla, JC; Lagos, NA; Cerda, M
Engineer species transform ecosystems due to their own growth, constitute an integral part of altered environments, and provide new habitats for other species, thus affecting biodiversity and the ecosystem. On rocky shores inside Antofagasta Bay (Northern Chile), the alien ascidian Pyura praeputialis, an engineer species, creates broad belts and dense 3-dimensional matrices that modify the intertidal habitat structure. In all, 116 species of macro-invertebrates and algae inhabit this habitat, compared with the 66 species inhabiting adjacent intertidal rocky shores which lack P, praeputialis. Of the 145 species recorded at the seascape scale (encompassing both mid-intertidal habitat), 55% were found exclusively in intertidal P. praeputialis matrices. Along the coastal gradient, patterns in beta-diversity emerge due to the addition of a new set of species to the community inhabiting the P. praeputialis matrices and, to a lesser extent, from spatial turnover. We found differences in the shape of the species frequency distribution between the communities inhabiting the engineered and non-engineered mid-intertidal habitats. However, within the same habitat type, there was no difference in the species frequency distribution between functional groups. Occurrence of macro-algae was not affected by habitat type, but occurence of macro-invertebrates increased significantly in R praeputialis matrices. P. praeputialis increases species richness at local and seascape scales by providing a novel mid-intertidal habitat which is used by mobile and vagile macro-invertebrates that otherwise would remain excluded from this intertidal level.
Patch recolonization by the tunicate Pyura praeputialis in the rocky intertidal of the Bay of Antofagasta, Chile
(2001) Alvarado, JL; Pinto, R; Marquet, P; Pacheco, C; Guiñez, R; Castilla, JC
Patch dynamics of intertidal Pyura praeputialis (Heller, 1838) were studied in experimentally cleared plots at 3 vertical levels (upper, mid arid lower P, praeputialis levels) and 3 sites within the Bay of Antofagasta, Chile. The sites corresponded approximately to the northern limit (Las Conchillas), the center (EL Way), and the southern limit (El Lenguado) of the species geographic distribution in Chile. Replicated 40 x 60 cm quadrats were photographed periodically to follow patch re-colonization. Patch recolonization (recolonized area) followed a sigmoid curve and could be fitted at most sites and levels by applying maximum likelihood techniques to the asymptotic model: y = a/{1 + exp[-(x - b)/c]} where Parameters a and b are asymptotic percentage cover and time for 50 % recovery respectively, and Parameter c defines the shape of the curve (growing phase). Among sites, the highest asymptotic values and fastest recovery times were observed at El Way, in the center of the species distribution. Among levels, the highest asymptotic values were observed in the mid P. praeputialis level quadrats. The perimeter of the patches increased and subsequently decreased as a function of recolonized area. Recruitment observations showed the process of recolonization to be related to the perimeter of the patch to be colonized rather than to the area available. Further more, the recolonization patterns could be predicted using the patch perimeter scaled by a linear coefficient. We believe that the mechanism of recolonization is most probably related to the settlement of recruits to the border of previously settled individuals, possibly mediated by intraspecific self-facilitation mechanisms.
Predator-inducible defences and local intrapopulation variability of the intertidal mussel Semimytilus algosus in central Chile
(2004) Caro, AU; Castilla, JC
Predator-inducible defences have a strong influence on the expression of morphological traits of intertidal invertebrates. For instance, mussels exposed to predators often have thicker shells than non-exposed. On the intertidal rocky shores of Chile, the mussel Semimytilus algosus is a preferred prey of many carnivorous invertebrates, including the snails Nucella crassilabrum and Concholepas concholepas, and the crab Acanthocyclus gayi. Preliminary observations indicated that S. algosus exists as 2 morphotypes: a thick, smooth shell and a thinner, ringed shell. The thick-shell morphotype was found mostly on compact, rocky platforms, whereas the thin one was found on emergent rocks. We examined the role of invertebrate predators in determining the morphological differences observed in S, algosus as a process of defence induction. The density and size of mussel predators showed significant differences between habitats: A. gayi dominating the platforms and N. crassilabrum emergent rocks. C. concholepas did not show differences between habitats. Water-borne cue experiments demonstrated that the mussel shell thickness is increased by the presence of predators, especially A. gayi. Furthermore, in contrast to the other predators, A. gayi preferentially selects mussels of the thin-shell morphotype. We demonstrate the cause and effect connection between variation in mussel shell morphology in the laboratory and their associated spatial distribution in the field, as well as the ecological role played by predators. We propose that, at local scales, the distribution and abundance of predators in the field explain the inter-population morphological differences of the mussel S. algosus.
Recent introduction of the dominant tunicate, Pyura praeputialis (Urochordata, Pyuridae) to Antofagasta, Chile
(2002) Castilla, JC; Collins, AG; Meyer, CP; Guiñez, R; Lindberg, DR
The large sessile tunicate Pyura stolonifera (Pleurogona: Stolibranchiata: Pyuridae), has been regarded as a complex taxon with disjointed distributions, including Australia (Pyura stolonifera praeputialis ), South Africa (Pyura stolonifera stolonifera ) and South America (Chile, Antofagasta: Pyura sp., the 'piure de Antofagasta'), and has been cited under at least five taxonomic combinations. The 'piure de Antofagasta' is a competitively dominant species in rocky intertidal habitats and shows a limited geographical range (60-70 km) exclusively inside the Bay of Antofagasta. Using cytochrome oxidase I (COI) mitochondrial sequence data from Pyura specimens of the three taxa we tested whether the Chilean taxon represents: (i) a Gondwana relict; (ii) a more recently divergent species; or (iii) a recently introduced species. The results suggest that the Chilean taxon is a recent introduction to Chile from Australian populations and that Pyura stolonifera praeputialis , from Australia, and the 'piure de Antofagasta' are geographical populations of a single species: Pyura praeputialis ; whereas the South African taxon represents a second species: Pyura stolonifera .
Recruitment of Homalaspis plana in intertidal habitats of central Chile and implications for the current use of Management and Marine Protected Areas
(2000) Fernández, M; Castilla, JC
Information about the life history of the stone crab Homalaspis plana was necessary to investigate the possible reasons for the failure of Marine Protected Area (MPA) and Management and Exploitation Area (MEA) in increasing stone crab abundance, in contrast with other exploited benthic species. In this study, we analyzed some aspects of the early Life history of the stone crab, focusing especially on (1) recruitment patterns among habitats and between years in intertidal zones, (2) habitat preferences, including some intra- and interspecific interactions that may affect habitat use, and (3) intraspecific interactions that may affect survival. We also evaluated the percent cover of suitable habitats for juvenile stone crabs in a MPA and a MEA. Sheltered habitats showed higher densities of juvenile H, plana than exposed areas, and sand with boulders showed the highest crab densities, followed by shell hash with boulders. Differences in mean densities were detected for all benthic stages among sheltered substrates, except for megalopae. Bare substrates (without boulders) showed the lowest density. Throughout the settlement period, abundance of smaller instars (J4 were twice as high in 1996 than in 1995. Neither intra- nor interspecific space competition seems to explain the distribution of juvenile stone crabs in the field. However, cannibalism among juveniles may have an important effect on survival. Cannibalism among juveniles is density-dependent, and may have greater effects as the abundance of larger conspecifics increases since mutual interference does not affect proportional prey mortality per predator. We suggest that losses are high in low quality habitats (probably through emigration, predation or habitat disturbance due to wave impact), and cannibalism is an important source of mortality in high quality habitats (where crab density is high). Although substrate type and post-settlement processes can help explain the distribution of juvenile stone crabs, wave action seems to be the major determinant of juvenile distribution. Neither sheltered habitats nor the most suitable substrate are common in the MPA and MEA studied. These factors are not currently being considered in the assignation of MEAs or planning of MPAs, although they could explain the lack of effect of both protection strategies in increasing the abundance of the stone crabs in Chile in comparison to other exploited benthic species.
Scales of benthic-pelagic and the intensity of species interactions: From recruitment limitation to top-down control
(2005) Navarrete, SA; Wieters, EA; Broitman, BR; Castilla, JC
Large and usually unpredictable variation in species interaction strength has been a major roadblock to applying local experimental results to large-scale management and conservation issues. Recent studies explicitly considering benthic-pelagic coupling are starting to shed light on,and find regularities in, the causes of such large-scale variation in coastal ecosystems. Here, we evaluate the effects of variation in wind-driven upwelling on community regulation along 900 km of coastline of the southeastern Pacific, between 29 degrees S and 35 degrees S during 72 months. Variability in the intensity of upwelling occurring over tens of km produced predictable variation in recruitment of intertidal mussels, but not barnacles, and did not affect patterns of community structure. In contrast, sharp discontinuities in upwelling regimes produced abrupt and persistent breaks in the dynamics of benthic and pelagic communities over hundreds of km (regional) scales. Rates of mussel and barnacle recruitment changed sharply at approximate to 32 degrees-33 degrees S, determining a geographic break in adult abundance of these competitively dominant species. Analysis of satellite images demonstrates that regional-scale discontinuities in oceanographic regimes can couple benthic and pelagic systems, as evidenced by coincident breaks in dynamics and concentration of offshore surface chlorophyll-a. Field experiments showed that the paradigm of top-down control of intertidal benthic communities holds only south of the discontinuity. To the north, populations seem recruitment-limited, and predators have negligible effects, despite attaining similarly high abundances and potential predation effects across the region. Thus, geographically discontinuous oceanographic regimes set bounds to the strength of species interactions and define distinct regions for the design and implementation of sustainable management and conservation policies.
Self-fertilization as an alternative mode of reproduction in the solitary tunicate Pyura chilensis
(2005) Manríquez, PH; Castilla, JC
The hermaphroditic broadcasting tunicate Pyura chilensis Molina, 1782 is a sessile filter-feeder organism that occurs in intertidal and subtidal habitat s along the Chilean and Peruvian coast. In natural populations, P. chilensis form dense aggregations, small patches or occur as isolated individuals. This suggests that self-fertilization could be a potential insurance against adverse conditions for cross-fertilization. In this study, P. chilensis were reared in the laboratory as isolated and paired individuals, to assess occurrence and success of fertilization, settlement and metamorphosis. Occurrence of self-fertilization was also compared between specimens forced to cross-fertilize and specimens maintained in reproductive isolation for different periods. We also manipulated cross- and self-fertilization using strip-spawned gametes. Our study shows that P. chilensis is a hermaphroditic species with adolescent gonochorism; that is, individuals first developed male function and then later male and female functions simultaneously as specimens increased in size (protandrous hermaphroditism). The results also show more frequent fertilization in paired specimens and in manipulated fertilization involving cross sperm. Moreover, no perceptible differences in fertilization, settlement, and metamorphosis success among self and outcross progeny were found. Prolonged periods of reproductive isolation resulted in more frequent self-fertilization. Occurrence of selling and highly successful settlement and metamorphosis of progeny originating from reproductively-isolated specimens suggest that even though outcrossing predominates, selling is an advantageous alternative when sources of allosperm are scarce.
Settlement of the gastropod Concholepas concholepas on shells of conspecific adults
(2004) Manríquez, PH; Navarrete, SA; Rosson, A; Castilla, JC
Competent larvae of the commercially important marine gastropod Concholepas concholepas (Gastropoda: Muricidae) 'loco', were collected in the field and exposed in the laboratory to adult conspecific shells with and without barnacle epibionts. Settlement and metamorphosis was induced by the presence of barnacles on shells of live or dead conspecifics, but not by C concholepas shells without barnacles. Results from laboratory experiments agreed well with field surveys showing the presence of recruits on conspecific shells overgrown with barnacles in shallow subtidal habitats (similar to3-30 m deep), suggesting the potential importance of barnacles inin inducing settlement and metamorphosis of locos under natural conditions. Most loco recruits were found below the C. concholepas shell apex, feeding on barnacles, inhabiting crevices among them, and inside dead barnacles. The mean size of recruits on locos' shells increased over four months from the beginning of the settlement season and no individual larger than 1.5 cm was observed, suggesting that they abandon adult loco shells at this size, roughly 5-6 months after settlement.

Browsing by Author "Castilla, JC"

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