UCN-CEAZA
Dispersal of post-larval macrobenthos in subtidal sedimentary habitats: Roles of vertical diel migration, water column, bedload transport and biological traits’ expression.
Pacheco, A., Uribe, R., Thiel, M., Oliva, M., & Riascos, J.
Post-larval dispersal along the sediment–water interface is an important process in the dynamics of macrobenthic populations and communities in marine sublittoral sediments. However, the modes of post-larval dispersal in low energy sublittoral habitats have been poorly documented. Herein we examined the specific dispersal mechanisms (diel vertical migration, water column, and bedload transport) and corresponding biological traits of the dispersing assemblage. At two sublittoral sites (sheltered and exposed) along the northern coast of Chile, we installed different trap types that capture benthic organisms with specific modes of dispersal (active emergence and passive water column drifting) and also by a combination of mechanisms (bedload transport, passive suspension and settlement from the water column). Our results show that even though there were common species in all types of traps, the post-larval macrobenthic assemblage depended on specific mechanisms of dispersal. At the sheltered site, abundant emerging taxa colonized sediments that were placed 0.5 m above the bottom and bedload-transported invertebrates appeared to be associated to the passive drifting of macroalgae. At the exposed site, assemblage dispersal was driven by specific mechanisms e.g. bedload transport and active emergence. At both sites the biological traits “small size, swimming, hard exoskeleton, free living and surface position” were associated to water column and bedload dispersal. This study highlights the importance of (i) the water–sediment interface for dispersal of post-larvae in sublittoral soft-bottom habitat, and (ii) a specific set of biological traits when dispersing either along the bottom or through the water column.
Año: 2013
Palabras claves: Emerging Benthos; Bottom Currents; Soft-bottom Communities; Humboldt Current Ecosystem.
Referencia APA: Pacheco, A., Uribe, R., Thiel, M., Oliva, M., & Riascos, J. (2013). Dispersal of post-larval macrobenthos in subtidal sedimentary habitats: Roles of vertical diel migration, water column, bedload transport and biological traits' expression. Journal Of Sea Research, 77, 79-92.
Learning about TURFs and natural variability: Failure of surf clam management in Chile.
Aburto, J. & Stotz, W.
Territorial User Rights for Fisheries (TURF) is considered an appropriate tool for small-scale fishery management. In Chile a TURFs system called Management Exploitation Areas for Benthic Resources (Áreas de Manejo y Explotación de Recursos Bentónicos-AMERB) were developed as a solution for the fishery crisis of Concholepas concholepas, a hard bottom snail. The success of these AMERBs led to its widespread application across different fisheries resources and social-ecological contexts, among them the surf clam Mesodesma donacium which has a highly variable population. Traditionally, fishermen followed the sporadically appearing M. donacium beds, migrating along the coast, a behavior now suppressed under the AMERB regime. We examined the dynamics of the M. donacium fishery, evaluating the performance of the AMERB system for its sustainable exploitation. Fishermen extracted surf clams based on monthly quotas, which were conservative. Despite this, after three years the fishery of M. donacium within the AMERB collapsed because of lack of recruitment and high natural mortality. The resulting low abundances made the fishery unattractive, causing the abandonment of the AMERB. This suggests that implementation of an AMERB system must integrate knowledge of the spatial scales over which different clam beds (subpopulations) are connected. While still ignoring the structure of the metapopulation, as occurs at present for M. donacium stocks in Chile, it could be evaluated to increase capture during the periods of boom, taking advantage of surf clams that will disappear in any case due to natural mortality. A spatial reserve within each clam bed could also be established in order to conserve the unknown but potentially important role of the subpopulation for the metapopulation.
Año: 2013
Palabras claves:
Referencia APA: Aburto, J. & Stotz, W. (2013). Learning about TURFs and natural variability: Failure of surf clam management in Chile. Ocean & Coastal Management, 71, 88-98.
Sea urchin Tetrapygus niger distribution on elevated surfaces represents a strategy for avoiding predatory sea stars
Urriago, J., Himmelman, J., & Gaymer, C.
We ran field experiments to examine whether the micro-distribution of the sea urchin Tetrapygus niger on elevated surfaces represents a strategy for limiting predation by the sea stars Heliaster helianthus and Meyenaster gelatinosus. Several lines of evidence supported this hypothesis. (1) A survey of the distribution of the urchin and the 2 sea stars showed that urchins occur mainly on elevated surfaces, and sea stars on low surfaces. (2) In trials involving simulated attacks, the time needed by the urchin to sever contact with the sea stars was 48% less on elevated surfaces than on the bottom. (3) In trials involving sustained simulated attacks (high predatory risk) the urchins could detach themselves from the elevated surfaces to avoid being eaten. Finally, tethering experiments indicated that the urchin had a higher survival rate on elevated than low surfaces. Our observations indicate that M. gelatinosus represents a stronger predatory threat to T. niger than H. helianthus.
Año: 2012
Palabras claves: Tetrapygus niger · Heliaster helianthus · Meyenaster gelatinosus · Predator−prey interactions · Aggregation · Distribution · Tethering
Referencia APA: Urriago, J., Himmelman, J., & Gaymer, C. (2012). Sea urchin Tetrapygus niger distribution on elevated surfaces represents a strategy for avoiding predatory sea stars. Marine Ecology Progress Series, 444, 85-95.
Effects of patch size and position above the substratum during early succession of subtidal soft-bottom communities.
Pacheco, A., Thiel, M., Oliva, M., & Riascos, J.
Early macrobenthos succession in small, disturbed patches on subtidal soft bottoms is facilitated by the arrival of post-larval colonizers, in particular by active and passive dispersers along the seafloor or through the water column. Using a field experiment at two contrasting sites (protected vs. exposed to wave action), we evaluated the role of (a) active and passive dispersal through the water column and (b) the influence of small-scale spatial variability during succession of subtidal macrobenthic communities in northern Chile. Containers of two sizes (surface area: small—0.12 m2 and large—0.28 m2) at two positions above the natural substratum (height: low—3 cm and high—26 cm) were filled with defaunated sediment, installed at two sandy sublittoral sites (7–9 m water depth) and sampled after 7, 15, 30, 60 and 90 days, together with the natural bottom sediment. The experiment took place during austral fall (from late March to early July 2010), when both larval and post-larval stages are abundant. At the exposed site, early succession was driven by similar proportions of active and passive dispersers. A sequence from early, late and reference communities was also evident, but container position and size affected the proportional abundance of dispersal types. At the protected site, the successional process started with abundant colonization of active dispersers, but toward the end of the experiment, the proportion of swimmer/crawlers increased, thus resembling the dispersal types found in the natural community. At this site, the position above the sediment affected the proportional abundance of dispersal types, but patch size had no effect. This study highlights that macrobenthic post-larvae can reach at least 26 cm high above the bottom (actively or passively, depending on site exposure), thus playing an important role during early succession of sublittoral soft bottoms. The active or passive use of the sediment–water interphase may also play an important role in the connectivity of benthic populations and in the recovery after large-scale disturbances of sublittoral habitats.
Año: 2012
Palabras claves: Colonization, Disturbance, Macrobenthos, Size effects, Recruitment, Active and passive dispersal, Humboldt, Current, System.
Referencia APA: Pacheco, A., Thiel, M., Oliva, M., & Riascos, J. (2012). Effects of patch size and position above the substratum during early succession of subtidal soft-bottom communities. Helgoland Marine Research, 66(4), 523-536.
Effects of predation and habitat structure on the abundance and population structure of the rock shrimp Rhynchocinetes typus (Caridea) on temperate rocky reefs.
Ory, N., Dudgeon, D., Dumont, C., Miranda, L., & Thiel, M.
Human disturbances, such as overfishing, may disrupt predator–prey interactions and modify food webs. Underwater surveys were carried out at six shallow-water reef barrens in temperate waters of northern-central Chile from October to December 2010 to describe the effects of predation, habitat complexity (low, medium and high) and refuge availability on the abundance and population structure of the rock shrimp Rhynchocinetes typus (Rhynchocinetidae), an important mesoconsumer on subtidal hard substrata. Three sites were within managed (restricted access) areas for fishermen, and three were unmanaged (open-access). Field observations and tethering experiments were conducted to examine the relationship between fish and shrimp abundances, and the relative predation rates on shrimps. Direct effects of predation on R. typus body-size distribution were examined from shrimps collected in the field and fish stomachs. The presence and the abundance of R. typus increased with habitat reef complexity and refuge availability. Shrimp abundance was negatively related to fish abundance in managed areas, but not in open-access areas, where shrimp densities were the highest. Also, predation rates and body-size distribution of shrimps were unrelated, although fish consumed more large shrimps than should be expected from their distribution in the field. R. typus occurred most often in shelters with wide openings, offering limited protection against predators, but providing potential aggregation sites for shrimps. Overall, direct effects of predation on shrimp densities and population structure were weak, but indirect effects on shrimp distribution within reefs appear to have been mediated through behavioural responses. Our study highlights the need to assess both numerical and behavioural responses of prey to determine the effects of predator loss on mesoconsumer populations.
Año: 2012
Palabras claves:
Referencia APA: Ory, N., Dudgeon, D., Dumont, C., Miranda, L., & Thiel, M. (2012). Effects of predation and habitat structure on the abundance and population structure of the rock shrimp Rhynchocinetes typus (Caridea) on temperate rocky reefs. Marine Biology, 159(9), 2075-2089.
Floating kelps in Patagonian Fjords: an important vehicle for rafting invertebrates and its relevance for biogeography.
Wichmann, C., Hinojosa, I., & Thiel, M.
Floating macroalgae are common dispersal vehicles for associated benthic invertebrates. In order to investigate the importance of kelp rafts for species dispersal in the Patagonian Fjord Region (PFR), the abundance and distribution pattern of floating kelps (Macrocystis pyrifera, Durvillaea antarctica) and of the invertebrate fauna associated with M. pyrifera were evaluated during austral spring of 2002–2005, 2008 and 2010. In the southernmost Magellan Region (MR), benthic M. pyrifera were additionally sampled to compare the community structures in both conditions. Floating kelps were abundant throughout the entire PFR, harbouring a diverse and abundant invertebrate fauna. The density of floating kelps increased towards the south. In the MR, a loss of species was observed between benthic and floating condition (e.g. decapods, echinoderms, several peracarid species), but a high diversity of organisms from all major phyla were observed on rafts. Throughout the PFR, the predominant rafting species belonged to the peracarids, molluscs and annelids, but the community composition differed between floating samples from the northern and southern zones of the PFR. Relative abundances of peracarids were higher in northern zones, whereas molluscs and annelids dominated in the southern areas. Species of the peracarid genera Peramphithoe, Gondogeneia, Bircenna and Limnoria were shared between all areas. The results suggest that kelp rafts not only contribute to local population connectivity in the PFR, but could also be an important dispersal vehicle for rafting species along the PFR in north–south direction, crossing the biogeographic boundary around Taitao Peninsula. Furthermore, the MR appears to be an important stepping stone for species dispersal via kelp rafting in the subantarctic region.
Año: 2012
Palabras claves:
Referencia APA: Wichmann, C., Hinojosa, I., & Thiel, M. (2012). Floating kelps in Patagonian Fjords: an important vehicle for rafting invertebrates and its relevance for biogeography. Marine Biology, 159(9), 2035-2049.
Reproductive biology of two species of squat lobsters – female receptivity and interbrood intervals.
Espinoza-Fuenzalida, N., Acuña, E., Hinojosa, I., & Thiel, M.
The reproductive biology of many species of anomuran crabs is only poorly known. Herein we studied the reproductive biology of two species of squat lobsters, Cervimunida johni Porter, 1903 and Pleuroncodes monodon (H. Milne Edwards, 1837), which are target of a trawl fishery operating on the continental margin along the Chilean coast. During the reproductive period (May-November) we maintained squat lobsters in the laboratory to examine whether mating is related to the reproductive molt of the female and to determine the interbrood interval between successive broods. In both species females mated during the intermolt period. Females became receptive shortly after having released larvae from a previous brood, when they formed pairs with males. The interbrood interval (from larval release until having a subsequent brood) lasted <72<72 hour in the majority of female C. johni, but was longer in P. monodon, where most females took 72-144 hours before producing a new brood. Despite longer interbrood intervals, copulatory mate-guarding was substantially shorter in P. monodon than in C. johni. These differences in reproductive behavior might be due to differences in the general biology of the two species, including mobility and intraspecific aggression. Mating during the intermolt period may have several advantages, namely reducing the risk of cannibalism and energy costs of molting during the reproductive season.
Año: 2012
Palabras claves: female receptivity, mating, reproduction, squat lobsters, trawl fishery.
Referencia APA: Espinoza-Fuenzalida, N., Acuña, E., Hinojosa, I., & Thiel, M. (2012). Reproductive biology of two species of squat lobsters – female receptivity and interbrood intervals. Journal Of Crustacean Biology, 32(4), 565-574
Microplastics in the Marine Environment: A Review of the Methods Used for Identification and Quantification.
Hidalgo-Ruz, V., Gutow, L., Thompson, R., & Thiel, M.
This review of 68 studies compares the methodologies used for the identification and quantification of microplastics from the marine environment. Three main sampling strategies were identified: selective, volume-reduced, and bulk sampling. Most sediment samples came from sandy beaches at the high tide line, and most seawater samples were taken at the sea surface using neuston nets. Four steps were distinguished during sample processing: density separation, filtration, sieving, and visual sorting of microplastics. Visual sorting was one of the most commonly used methods for the identification of microplastics (using type, shape, degradation stage, and color as criteria). Chemical and physical characteristics (e.g., specific density) were also used. The most reliable method to identify the chemical composition of microplastics is by infrared spectroscopy. Most studies reported that plastic fragments were polyethylene and polypropylene polymers. Units commonly used for abundance estimates are “items per m2” for sediment and sea surface studies and “items per m3” for water column studies. Mesh size of sieves and filters used during sampling or sample processing influence abundance estimates. Most studies reported two main size ranges of microplastics: (i) 500 μm–5 mm, which are retained by a 500 μm sieve/net, and (ii) 1–500 μm, or fractions thereof that are retained on filters. We recommend that future programs of monitoring continue to distinguish these size fractions, but we suggest standardized sampling procedures which allow the spatiotemporal comparison of microplastic abundance across marine environments.
Año: 2012
Palabras claves:
Referencia APA: Hidalgo-Ruz, V., Gutow, L., Thompson, R., & Thiel, M. (2012). Microplastics in the Marine Environment: A Review of the Methods Used for Identification and Quantification. Environmental Science & Technology, 46(6), 3060-3075.
Effect of two temperatures on ammonia excretion rates of Seriolella violacea (Palm fish) juveniles under rearing conditions.
Nerici, C., Silva, A., & Merino, G.
Nitrogenous compounds can be toxic to aquatic animals, especially when they are reared for production purposes at high stocking densities. Seriolella violacea is a pelagic fish, native from the easterly South Pacific Ocean. This species has shown desirable behavioral and metabolic characteristics under captivity conditions, which leaded the Marine Fish Laboratory from the UCN to increase its efforts on the research and development to validate S. violacea as a new aquaculture option. Therefore, the objective of this study is to determine the excretion rates of palm fish juveniles weighing 300–500 g at two different temperatures: 14 °C and 18 °C. Total ammonia as nitrogen (TAN) excreted was 4.4 ± 0.9 and 7.1 ± 1.9 mg TAN/kg fish/h for 14 °C and 18 °C respectively. The experiments were carried out in a recirculating system operating as a farm-like situation. Tests were performed in 1000 L rearing tanks operating as open respirometers. The results of the present study indicate that TAN excretion rates on S. violacea juveniles, is temperature dependent. Data obtained in these experiments are valuable information for the engineering design of land based aquaculture systems for palm fish.
Año: 2012
Palabras claves: Seriolella violacea; Excretion rates; Ammonia; Recirculating aquaculture system; Water quality
Referencia APA: Nerici, C., Silva, A., & Merino, G. (2012). Effect of two temperatures on ammonia excretion rates of Seriolella violacea (Palm fish) juveniles under rearing conditions. Aquacultural Engineering, 46, 47-52.
Floating Seaweeds and Their Communities.
Rothäusler, E., Gutow, L., & Thiel, M.
A wide diversity of floating seaweeds is found in temperate and subpolar regions of the world’s oceans where sea surface currents and winds determine their traveling velocities and directions. The importance of floating seaweeds as dispersal agents for associated organisms and for the algae themselves varies depending on the supply from benthic source populations and on their persistence at the sea surface. Persistence of floating algae depends on water temperature, grazing activity, epifaunal load, and, to a lesser extent, on prevailing irradiance conditions. In temperate regions, persistence of floating algae is primarily limited by warm sea surface temperatures and high densities of motile and sessile epifauna whereas at higher latitudes algae can successfully compensate grazer-induced tissue loss by continuous growth at the prevailing low water temperatures. Accordingly, floating seaweeds can bridge large oceanic distances especially at high latitudes allowing for connectivity among distant benthic populations of algae and associated rafters.
Año: 2012
Palabras claves:
Referencia APA: Rothäusler, E., Gutow, L., & Thiel, M. (2012). Floating Seaweeds and Their Communities. Ecological Studies, 359-380.
Authentication of commercialized crab-meat in Chile using DNA Barcoding.
Haye, P., Segovia, N., Vera, R., Gallardo, M., & Gallardo-Escárate, C.
Authentication of commercialized marine products has become a market priority. Crustaceans are benthic marine resources highly exploited in Chile. Brachyuran crabs are of particular interest and in Chile are commercialized with different processing and presentations. Generally, Chilean brachyuran crab-meat commercial packages do not include taxonomic information, which in addition to the loss of diagnostic characters during the processing, impedes the identification of species being commercialized. The goal of this study was to determine which brachyuran species are being commercialized in the Chilean market using DNA Barcoding and phylogenetic analysis. For authentication of commercial crab-meat and DNA Barcoding a partial sequence of the Cytochrome Oxidase I (COI) gene of seven commercialized brachyuran species in Chile were used. For authentication, samples were obtained from seven commercial formats available on the local market in Coquimbo, Chile. Most commercial packages contained more than one species of crab. The Species detected in order of frequency are Metacarcinus edwardsii, Romaleon polyodon, Cancer porteri, Cancer plebejus, and Homalaspis plana. Mislabeling was detected in one of the commercial formats that declared including meat from Cancer species. The procedure presented herein, based on standard DNA Barcoding as well as phylogenetic analyses, can be used for the normative control of crab-meat processed products.
Año: 2012
Palabras claves: Food authentication; DNA Barcoding; Crab meat; Species identification; Mislabeling; Conservation genetics
Referencia APA: Haye, P., Segovia, N., Vera, R., Gallardo, M., & Gallardo-Escárate, C. (2012). Authentication of commercialized crab-meat in Chile using DNA Barcoding. Food Control, 25(1), 239-244.
Genetic signatures of rafting dispersal in algal-dwelling brooders Limnoria spp. (Isopoda) along the SE Pacific (Chile).
Haye, P., Varela, A., & Thiel, M.
ABSTRACT: Brooding marine isopods of the genus Limnoria inhabit and feed on kelp holdfasts and wood. These substrata have high floating potential, making these species ideal organisms to study the effects of rafting-mediated connectivity on the population structure of brooders living on rafting substrata. It is hypothesized that rafting leaves particular genetic signatures such as low differentiation among distant local populations and absence of isolation by distance (IBD) at a macro-geographic scale (thousands of km). Using cytochrome oxidase I (COI) sequences, we tested the effects of rafting-mediated gene flow with respect to genetic differentiation on L. quadripunctata (from wood and also the holdfasts of the giant kelp Macrocystis pyrifera) and L. chilensis (mainly from the bull kelp Durvillaea antarctica) sampled across 2400 km of the Chilean coast. Analyses of COI data for both species indicated low differentiation between distant locations along the Chilean coast and lack of IBD, bearing the expected genetic signatures of rafting dispersal. Phylogenetic analyses were performed with COI and the nuclear gene 28S to place the genetic diversity of Chilean Limnoria spp. into a wider geographical context. Both markers revealed that L. quadripunctata from Chile is a sister clade to other Limnoria spp. analyzed (L. chilensis, L. segnis, and L. stephenseni), which mainly inhabit D. antarctica. L. chilensis from Chile and subantarctic islands form a tight monophyletic group. Phylogenetic and phylogeographic analyses show that along the studied area, L. quadripunctata and L. chilensis have the genetic signatures of relatively recent or ongoing rafting.
Año: 2012
Palabras claves: Peracarids, Rafting, Biogeography, Mitochondrial DNA, COI, 28S, Phylogeny, Phylogeography
Referencia APA: Haye, P., Varela, A., & Thiel, M. (2012). Genetic signatures of rafting dispersal in algal-dwelling brooders Limnoria spp. (Isopoda) along the SE Pacific (Chile). Marine Ecology Progress Series, 455, 111-122.