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Pacific Coast (pacific + coast)
Selected AbstractsPRESENCE OF SPOROPHYLLS IN FLOATING KELP RAFTS OF MACROCYSTIS SPP. (PHAEOPHYCEAE) ALONG THE CHILEAN PACIFIC COAST,JOURNAL OF PHYCOLOGY, Issue 5 2005Erasmo C. Macaya Some species of macroalgae continue to live for extended periods of time after detachment and may even maintain reproductive structures, yet very little is known about this process. Here, we describe the presence of sporophylls (with sporogenous tissues) on floating kelp rafts of Macrocystis spp. along the coast of Chile. Surveys were conducted at nine sites (18,50° S) during austral summer 2002, and floating kelp rafts were seen and collected at seven of these nine sites (between 22 and 50° S). Fifteen (26.8%) of the 56 samples had sporophylls, indicating maintenance of sporophylls after detachment. Some of the kelp sporophytes with reproductive blades showed signs of having been afloat for long periods (indicated by the large size of attached stalked barnacles). Additionally, experiments showed that floating kelps released viable zoospores. To understand the reproductive dynamics of floating kelps, we compared these results with information from attached populations of Macrocystis spp. at nearby coastal sites. In general, attached kelp had higher proportions of sporophylls than floating rafts, suggesting that detachment may negatively affect reproductive status. Nevertheless, floating kelps remained functionally reproductive, suggesting that zoospores may be dispersed via floating rafts. Published reports on other macroalgae indicate that some species (Lessoniaceae, Fucaceae, and Sargassaceae) are fertile and probably release zoospores or zygotes while floating or drifting in ocean currents. Because dispersal distances achieved by spores of most macroalgae are relatively short, release of spores from floating algae may be an alternative mechanism of long-distance dispersal. [source] Associations between host migration and the prevalence of a protozoan parasite in natural populations of adult monarch butterfliesECOLOGICAL ENTOMOLOGY, Issue 2 2000Sonia M. Altizer Summary 1. Monarch butterflies Danaus plexippus (L.) (Lepidoptera: Nymphalidae) are susceptible to infection by the obligate protozoan parasite Ophryocystis elektroscirrha (McLaughlin and Myers) (Apicomplexa: Neogregarinida). Because monarchs form resident and migratory populations in different parts of the world, this host,parasite system provides the opportunity to examine how variation in parasite prevalence relates to host movement patterns. 2. Parasite prevalence was evaluated using 14 790 adult monarchs captured between 1968 and 1997. Comparison of three populations in North America indicated that parasite prevalence is associated negatively with host dispersal distances. A continuously breeding, nonmigratory population in southern Florida showed high prevalence (over 70% heavily infected). The western population migrates moderate distances to overwintering sites on the Pacific Coast and has intermediate prevalence (30% heavily infected). The eastern migratory population, which travels the longest distance to Mexican overwintering sites, has exhibited less than 8% infection throughout the past 30 years. 3. Variation in parasite loads within North American migratory populations was investigated to determine whether the prevalence of heavy infection and average parasite loads declined during migration or overwintering. Average parasite loads of summer-breeding adults in western North America decreased with increasing distance from overwintering sites. This suggests that heavily infected monarchs are less likely to remigrate long distances in spring. No differences in the frequency of heavily infected adults were found among eastern or western North American monarchs throughout the overwintering period, however, suggesting that this parasite does not affect overwintering mortality. 4. Changes in the prevalence of monarchs with low parasite loads demonstrate that spore transfer occurs during migration and overwintering, possibly when adult butterflies contact each other as a result of their clustering behaviour. 5. This study of geographical and temporal variation in O. elektroscirrha among populations of D. plexippus demonstrates the potential role of seasonal migration in mediating interactions between hosts and parasites, and suggests several mechanisms through which migratory behaviour may influence parasite prevalence. [source] VICARIANCE AND DISPERSAL ACROSS BAJA CALIFORNIA IN DISJUNCT MARINE FISH POPULATIONSEVOLUTION, Issue 7 2003Giacomo Bernardi Abstract., Population disjunctions, as a first step toward complete allopatry, present an interesting situation to study incipient speciation. The geological formation of the Baja California Peninsula currently divides 19 species of fish into disjunct populations that are found on its Pacific Coast and in the northern part of the Gulf of California (also called the Sea of Cortez), but are absent from the Cape (Cabo San Lucas) region. We studied the genetic makeup of disjunct populations for 12 of these 19 fish species. Phylogeographic patterns for the 12 species can be separated into two major classes: a first group (eight species) showed reciprocal monophyly and high genetic divergence between disjunct populations. A second group (four species) displayed what appeared to be panmictic populations. Population structure between Pacific Coast populations, across the Punta Eugenia biogeographic boundary, was also evaluated. While dispersal potential (inferred by pelagic larval duration) was a poor predictor of population structure between Gulf of California and Pacific populations, we found that population genetic subdivision along the Pacific Coast at Punta Eugenia was always positively correlated with differentiation between Pacific and Gulf of California populations. Vicariant events, ongoing gene flow, and ecological characteristics played essential roles in shaping the population structures observed in this study. [source] THE NON-PENNSYLVANIA TOWN: DIFFUSION OF URBAN PLAN FORMS IN THE AMERICAN WEST,GEOGRAPHICAL REVIEW, Issue 2 2006MICHAEL P. CONZEN ABSTRACT. Wilbur Zelinsky's classic 1977 account of the Pennsylvania town as a cultural place type,the urban component of the nationally influential Pennsylvanian culture region,acknowledged that it was not exported intact across the successive western frontiers of the United States. But, aside from Edward Price's specialized study of courthouse squares, we know little that is systematic about how town-planning ideas diffused across the continent. This investigation offers evidence from the Willamette Valley in Oregon of the eventual variety and geographical distribution of town-platting conventions that developed in this Pacific Coast "destination' setting and the possible provenance in the Ohio Valley of certain early Oregonian town-plan features. The evidence raises questions about the resilience of town-planning conventions in light of the distance carried, cultural time lags, and changing ideas about best practice and local suitability. [source] Assessment Tools for Urban Catchments: Developing Stressor Gradients,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 2 2009David W. Bressler Abstract:, This is the first in a series of three articles designed to establish empirically defined biological indicators and thresholds for impairment for urbanized catchments, and to describe a process by which the biological condition of waterbodies in urbanized catchments can be applied. This article describes alternative gradients of urbanization for assessing and selecting a nationally applicable biological index (article 2 ,Purcell et al., this issue) and defining the potential of biological communities within a gradient of cumulative stressors (article 3 ,Paul et al. this issue). Gradients were designed to represent the most prominent mosaic of stressors found in urban settings. A primary urban gradient was assembled based on readily obtained information of urbanization to include three broad-scale parameters: percent urban land use/land cover, population density, and road density. This gradient was used as the standard by which alternative urban gradients, which included fine-scale instream chemical and hydrologic parameters, were assessed. Five alternative gradients were developed to provide numerous environmental management options based on availability of data from water program resources. The urban gradients were developed with the intent that they be applied throughout the country; therefore, data from three different regions of the United States (Mid-Atlantic, Midwest, and Pacific Coast) were used to validate the urban gradient model. Our study showed that a relatively straightforward stressor gradient consisting of human population density, road density, and urban land use is useful in providing a framework for developing relevant biological indicators and evaluating the potential of biological communities as a basis for assessing attainment of designated aquatic life use. [source] Prevention of sporogony of Plasmodium vivax in Anopheles albimanus by steroids of Solanum nudum Dunal (Solanaceae)PHYTOTHERAPY RESEARCH, Issue 6 2006Eliana Arango Abstract The sporontocidal activity of three steroids (SN-1, SN-2 and SN-4) from Solanum nudum Dunal (Solanaceae) was determined against naturally circulating isolates of Plasmodium vivax in Anopheles albimanus. Laboratory-reared Anopheles albimanus mosquitoes were infected with P. vivax from gametocytemic blood of volunteers resident in Buenaventura, Valle del Cauca (Colombian Pacific Coast) by using an artificial membrane feeder. Prior to mosquito feeding, gametocytemic blood was centrifuged, plasma was separated, packed blood red cells were washed with RPMI 1640 and then resuspended in non-immune AB serum, then the steroids were added at different doses. On day 7 after infection, the presence and number of oocysts in mosquitoes was determined. The steroid SN-2 reduced the infection of mosquitoes by 90% and the mean number of oocysts by 60%. These data confirmed that the experimental steroid is capable of interrupting the sporogonic development of P. vivax in Anopheles albimanus. This experimental steroid has potential for transmission blocking in vivax malaria. Copyright © 2006 John Wiley & Sons, Ltd. [source] EVOLUTION OF POECILOGONY AND THE BIOGEOGRAPHY OF NORTH AMERICAN POPULATIONS OF THE POLYCHAETE STREBLOSPIOEVOLUTION, Issue 4 2000Stefan R. Schulze Abstract. Invertebrate interspecific developmental patterns can be highly variable and, taxonomically, are considered only weakly constrained. Intraspecifically, some invertebrate species possess multiple developmental modes,a condition known as poecilogony. Closer examination of most putative poecilogenous species, however, has not supported poecilogony, but rather has uncovered hidden or cryptic species. The polychaete Streblospio benedicti is a well-known, poecilogenous species found along the coast of North America. We collected mitochondrial cytochrome subunit I DNA sequence data from 88 individuals taken from 11 locations along the Atlantic, Gulf, and Pacific Coasts of the United States to provide a phylogenetic framework from which to interpret intraspecific variation in larval life history and brooding structure morphology in this species. Our results are consistent with a recent revision of the species into two separate species: S. benedicti, a pouched brooding form distributed along the Atlantic and Pacific Coasts, and S. gynobranchiata, a branchiate brooding form in the Gulf of Mexico. Contrary to the redescription, S. benedicti is paraphyletic because the pouched brooding population in Vero Beach, Florida shows strong genetic affinity with Gulf of Mexico populations (S. gynobranchiata). However, S. benedicti is a true poecilogenous species, with both lecithotrophic and planktotrophic individuals possessing identical mitochondrial DNA haplotypes. Crossbreeding experiments further support the molecular phylogeny with reproductive isolation demonstrated between, but not within, the major phylogenetic clades consistent with the previously described species. The genetic break near Vero Beach, Florida, corresponds to a well-known phylogeographic boundary, but the estimated time of separation for the Streblospio spp., approximately 10 million years before present, predates all other known phylogeographic subdivisions in this area. This suggests that biogeographic sundering in this region is a recurrent event. Divergence times within the major Streblospio spp. clades are recent and indicate that changes in larval life history as well as brooding structure morphology are highly plastic and can evolve rapidly. [source] Trade-Offs between Species Conservation and the Size of Marine Protected AreasCONSERVATION BIOLOGY, Issue 1 2010P. M. CHITTARO áreas marinas protegidas; conservación de la biodiversidad; relaciones especies,área Abstract:,Moving from single-species- to ecosystem-based management requires an understanding of how community-level attributes such as diversity change with area. We used survey data from bottom trawls to examine spatial patterns of species richness in U.S. Pacific coastal fishes. Specifically, we generated and compared species,area relationships (SARs) for species classified into several groups on the basis of maximum body size, trophic level, diet, maximum depth, geographic affinity, and taxonomic order. Because SARs among groups were not parallel and z values varied significantly for several groups, groups of species were under- or overrepresented (depending on the size of the area) relative to their proportions in the entire community (i.e., entire U.S. Pacific coast). In this way, differences in SARs help demonstrate trade-offs between species representation and coastal area and suggest strategies (such as targeting the protection of habitats and locations where a particular species or groups of species are maximized) that may minimize the size of marine protected areas (MPAs) but protect diversity at the level of the community and functional group. Resumen:,El traslado del manejo de una sola especie al manejo basado en ecosistemas requiere del entendimiento de los cambios en atributos de la comunidad como el cambio de diversidad con el área. Utilizamos datos de muestreo de redes de arrastre para examinar patrones espaciales de la riqueza de especies en peces costeros del Pacífico en E. U. A. Específicamente, generamos y comparamos relaciones especies,área (REAs) para especies clasificadas en varios grupos con base en la talla máxima, nivel trófico, profundidad máxima, afinidad geográfica y orden taxonómico. Debido a que las REAs entre grupos no fueron paralelas y que los valores de z variaron significativamente para varios grupos, los grupos de especies estuvieron sub- o sobre- representados (dependiendo del tamaño del área) en relación con sus proporciones en toda la comunidad (i.e., toda la costa del Pacífico en E. U. A.). De esta manera, las diferencias en REAs ayudan a demostrar el balance entre la representación de especies y el área costera y sugieren estrategias (como la protección de hábitats y localidades donde se maximiza una especie o grupo de especies) que pueden minimizar el tamaño de áreas marinas protegidas pero proteger la diversidad al nivel de la comunidad y grupo funcional. [source] Morphometry and sexual dimorphism of the coastal spotted dolphin, Stenella attenuata graffmani, from Bahía de Banderas, MexicoACTA ZOOLOGICA, Issue 4 2004Laura Sanvicente-Añorve Abstract External measurements and size differences between the sexes were examined in the coastal spotted dolphin, Stenella attenuata graffmani, in Bahía de Banderas, on the Mexican Pacific coast. The dolphins were collected by local fishermen and 29 external characteristics were measured by members of the Marine Mammals Laboratory, University of Mexico. The length of each characteristic with respect to total length was analysed through adjustment of the data to a power equation. A stepwise discriminant analysis was applied to the absolute values and to those expressed as proportions to analyse the differences between the sexes. Results indicate that growth in these dolphins is generally negatively allometric, and most of the characteristics measured were, in both absolute and proportional terms, greater in male dolphins than in female dolphins. As found in many species of odontocetes, the discriminant analysis showed that the main differences between the sexes for this coastal subspecies include the relative positions of the umbilicus, the genital aperture and the anus. The morphometric data provided by this study, corresponding to 29 specimens of S. a. graffmani collected in a restricted locality of the Mexican Pacific coast, are particularly interesting to studies documenting latitudinal morphological differences in the coastal spotted dolphin. [source] Body size and invasion success in marine bivalvesECOLOGY LETTERS, Issue 2 2002Kaustuv Roy The role of body size in marine bivalve invasions has been the subject of debate. Roy et al. found that large-bodied species of marine bivalves were more likely to be successful invaders, consistent with patterns seen during Pleistocene climatic change, but Miller et al. argued that such selectivity was largely driven by the inclusion of mariculture species in the analysis and that size-selectivity was absent outside of mariculture introductions. Here we use data on non-mariculture species from the north-eastern Pacific coast and from a global species pool to test the original hypothesis of Roy et al. that range limits of larger bivalves are more fluid than those of smaller species. First, we test the hypothesis that larger bivalve species are more successful than small species in expanding their geographical ranges following introduction into new regions. Second, we compare body sizes of indigenous and non-indigenous species for 299 of the 303 known intertidal and shelf species within the marine bivalve clade that contains the greater number of non-mariculture invaders, the Mytilidae. The results from both tests provide additional support for the view that body size plays an important role in mediating invasion success in marine bivalves, in contrast to Miller et al. Thus range expansions in Recent bivalves are consistent with patterns seen in Pleistocene faunas despite the many differences in the mechanisms. [source] Seasonal changes in the reproduction of three oncaeid copepods in the surface layer of the Kuroshio ExtensionFISHERIES OCEANOGRAPHY, Issue 2004KAORU NAKATA Abstract Seasonal changes in reproduction rates of three dominant oncaeids, Oncaea media, O. venusta f. venella and O. venusta f. ,1, and effects of environmental factors on them were examined in the surface layer (0,30 m) in the Kuroshio Extension and adjacent waters off the Pacific coast of central Japan. The biomass of oncaeid copepods peaked in spring, and remained at about 14% of total copepod biomass throughout the year. Monthly mean specific egg production rates of O. media, O. venusta f. ,1 and O. venusta f. venella ranged from 0 to 0.038 day,1, from 0.026 to 0.051 day,1 and from 0.022 to 0.049 day,1, respectively, and were relatively higher from winter to spring. Specific egg production rates of both O. media and O. venusta f. venella were positively related to primary production in the euphotic layer. Analysis of temperature effects on reproduction parameters indicated that low temperature was one cause for high specific egg production rates of O. venusta f. ,1 in winter, mainly because of an increase in clutch size. Environmental factors thus affect reproduction of the dominant oncaeids in the surface layer of the Kuroshio Extension, and an increase in temperature and decline in primary production would reduce their reproduction. [source] A spatial model of population dynamics of the early life stages of Japanese sardine, Sardinops melanostictus, off the Pacific coast of JapanFISHERIES OCEANOGRAPHY, Issue 2 2003Maki Suda Abstract We constructed a numerical model reproducing the transport, survival and individual growth of the early life stages of Japanese sardine, Sardinops melanostictus, off the Pacific coast of Japan during 1978,93. The causes of early life stage mortality, including the influence of the effects of the spatial relationship between the spawning grounds and the Kuroshio on the mortality rate, were investigated. Survival and transport from egg stage to 60 days after spawning were modelled daily in a 1 × 1 degree mesh cell and individual growth in the period was modelled in each region (Kuroshio, Inshore, Offshore and Transition regions). Individual growth and survival from 60 to 180 days after spawning were modelled daily in the Transition region. Environmental data were taken from outside the model system. Our simulation indicates that survival variability in the larval stage (5,25 mm in standard length) is the key factor in determining the year-class strength. The simulation revealed that strong year classes occurred with good survival in the spawning ground and whilst entrained in the Kuroshio current being transported to the main feeding grounds in the Transition region. The simulation also indicated that survival rates in 1988,93 were low in the Inshore, Kuroshio and Offshore regions, which depressed the year-class strength during that period. [source] Interannual variation in spring biomass and gut content composition of copepods in the Kuroshio current, 1971,89FISHERIES OCEANOGRAPHY, Issue 4 2001K. Nakata We examined the effects of climate factors on interannual variations of copepod biomass and gut content composition in early spring in the Kuroshio and the slope water off the Pacific coast of central Japan from 1971 to 1989. The biomass trends were different for large (prosomal length , 1 mm) and small (prosomal length < 1 mm) copepods in both waters. Peaks in biomass of large copepods decreased in magnitude, and the biomass of small copepods was low around 1980. For the large copepods in the Kuroshio, 3-year running mean biomass was related to the Kuroshio meander index. The yearly mean biomass was related to diatom abundance in the gut which, in turn, was related to wind speed and temperature. The 3-year running mean biomass of large copepods in the slope water was positively related to solar radiation in March. The biomass of small copepods in both waters was negatively related to solar radiation in February, and years with high biomass of small copepods corresponded with not only the years with high abundance of larger foods (diatoms and micro-sized foods) in copepod guts, but also with the years with high abundance of the nano-sized foods. We hypothesize that nutrient supply to upper layers regulates interannual variation of biomass of large copepods in the Kuroshio. Thus, climate influences both size composition and biomass of copepods in and near the Kuroshio in early spring. [source] Early Cretaceous bivalves of the Neuquén Basin, west-central Argentina: notes on taxonomy, palaeobiogeography and palaeoecologyGEOLOGICAL JOURNAL, Issue 2 2007Dario G. Lazo Abstract This paper provides an updated taxonomic inventory of the bivalve fauna collected in the Pilmatué Member of the Agrio Formation of the Neuquén Basin, west-central Argentina, places the fauna in its palaeobiogeographic setting, and addresses its palaeoecological significance. Thirty-one Late Valanginian to Early Hauterivian bivalve species within 24 genera were identified. A large part (32%) of the identified bivalve species occur over a wide geographical area: from the Pacific coast of South America to Europe, North Africa, Central Asia and East and South Africa; some are also recorded in Japan. A relatively high degree of endemism (26%) is shown, suggesting that some of the bivalve species had barriers to their dispersal; larval strategy and length of larval development were probably important. A significant number (42%) of the bivalve taxa are left in open nomenclature as they are probably new species. Bivalve guilds are described to interpret palaeoecology, in particular the ecospace utilization. Guilds are based on tiering, life habit, and feeding category. Eight guilds are recognized: free-lying epifaunal, cemented epifaunal, epibyssate, boring, endobyssate, shallow burrowing, deep burrowing and deep burrowing with symbiotic bacteria. The fauna is composed only of suspension-feeders indicating that food resources were dominantly in suspension, in agreement with the predominantly shallow-water aspect of the study deposits. The ecospace utilization in the shoreface is broader than in the offshore shelf, suggesting more favourable living conditions and/or a wider range of different habitat types represented. Copyright © 2007 John Wiley & Sons, Ltd. [source] Breeding biology and conservation of the Black-vented Shearwater Puffinus opisthomelasIBIS, Issue 4 2003Bradford S. Keitt The Black-vented Shearwater Puffinus opisthomelas is endemic to the Pacific coast of Baja California, Mexico. We studied the breeding biology of this species at Natividad Island in 1997 and 1998. The colony at Natividad Island covers approximately 2.5 km2 and we estimated there to be 114 455 (± 27 520 95% CI) burrows in the colony. In 1997 burrow occupancy was 66.9%, providing a population estimate of 76 570 (± 18 411 95% CI) breeding pairs, representing about 95% of the world's population of this species. In 1997 the peak in egg laying occurred in early March and hatching began on 7 May. The incubation period averaged 51 days (± 6 sd) and chick rearing averaged 69 days (± 3 sd). In 1998 burrow occupancy was lower (19.6%) and nest initiation was later (peak egg laying in mid-April), perhaps a result of El Niño conditions that prevailed in the Eastern Pacific at that time. We calculated that the development of the town and roads on Natividad Island have destroyed over 15% (26 532 burrows) of the breeding habitat on the island. [source] Osteobiography of a high-status burial from the lower Río Verde Valley of Oaxaca, MexicoINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 6 2008A. T. Mayes Abstract This paper presents the osteobiography of an individual from an early complex society who was clearly of "special" social status but was not classified a ruling elite. Our case derives from a unique burial found at the small site of Yugüe, located in the lower Río Verde valley on the Pacific coast of Oaxaca, Mexico. Burial 14-Individual 16 (B14-I16) dates to the late Terminal Formative Period (CE 100,250), an era of regional political centralization and concomitant social inequality. B14-I16 was interred with several valuable grave offerings. A plaster-backed pyrite mirror was found below his mandible, and his left hand held an elaborately incised flute made from a deer femur. The flute is the only object of its kind known for all of Terminal Formative Mesoamerica. Drawing on the physicality of inequality, we employ osteobiography to assess the social hierarchy. Although B14-I16 was clearly an individual of unusual status in the context of Yugüe, he was not immune from the biological assaults that affected people of less distinguished social position at this time. Like his contemporaries of all social statuses, he suffered ill health in the years during which he was weaned. However, a longer weaning period and access to additional resources may have positioned him to endure later illness better than others in this population. Passing the critical transition period at age 6 ½, a time when many children died in this burial site, his adolescent health was better than that of others in this population. Although B14-I16 did have adult responsibilities, he didn't engage in the kinds of physical labour that marked the skeletons of others. The placement of Burial B14-I16 in the middle tiers of the lower Río Verde valley's ancient social hierarchy provides insight into issues of inequality and status on an individual scale. Copyright © 2008 John Wiley & Sons, Ltd. [source] Fishing in Peru between 10,000 and 3750 BPINTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 1-2 2001Elizabeth J. ReitzArticle first published online: 28 FEB 200 Abstract Archaeozoological data for the period of 10,000,5000 bp were rare for the southeastern Pacific coast, until recent work provided data from eight sites in Peru and Ecuador. These sites span the early to mid-Holocene period, during which time modern climatic conditions became established. Vertebrate faunal data from these sites provide an opportunity to explore the influence of mid-Holocene environmental changes on fishing in Peru during this time. With two exceptions, most faunal collections are dominated by marine animals, with virtually no terrestrial vertebrates. Many of the marine organisms are catholic species, tolerant of a wide variety of water conditions, rather than ones which clearly prefer warm,tropical or warm,temperate ones. Warm,tropical species are more common in the northern assemblages, as would be expected. There is a temporal pattern as well. Within three subdivisions of this area, warm,tropical animals diminish in abundance, and warm,temperate animals increase. These differences probably reflect cultural responses to mid-Holocene environmental change, in which coastal waters from southern Peru into Ecuador became cooler. Copyright © 2001 John Wiley & Sons, Ltd. [source] Life history of Littorina scutulata and L. plena, sibling gastropod species with planktotrophic larvaeINVERTEBRATE BIOLOGY, Issue 1 2002Paul A. Hohenlohe Abstract. The intertidal, sibling species Littorina scutulata and L. plena (Gastropoda, Proso-branchia) are sympatric throughout most of their ranges along the Pacific coast of North America. Both species release disc-shaped, planktonic egg capsules from which planktotrophic veliger larvae hatch. Here I review existing data and present new observations on these species' life history, including age at first reproduction, spawning season, maximum fecundity rates, capsule morphology, egg size and number, pre-hatching development, larval growth at three food concentrations, potential settlement cues, planktonic period, and protoconch size. Previous classification of egg capsule morphologies used to distinguish the species is inaccurate; instead, capsules can be categorized into three types of which each species may produce two. Females of L. scutulata produced capsules with either two rims of unequal diameter or one rim, while females of L. plena produced capsules with one rim or two rims of nearly equal diameter. Females of each species spawned sporadically from early spring to early fall in Puget Sound. Larvae of L. plena hatched one day earlier than those of L. scutulata, and both species grew fastest in the laboratory at intermediate food concentrations. Larvae metamorphosed in the presence of a variety of materials collected from their adult habitat, including conspecific adults, algae, rocks, and barnacle tests. This is the first report of planktotrophic larvae in this genus metamorphosing in the laboratory. The total planktonic period of 8 larvae of L. scutulata raised in the laboratory was 37,70 days, and a single larva of L. plena metamorphosed after 62 days. Protoconch diameter of shells collected from the field was 256,436 ,m and did not differ significantly between the species. Previous allozyme and mitochondrial DNA work has suggested high levels of genetic variability in both species and greater genetic population structure in L. plena, despite the long spawning season and long-lived larvae in both species. The interspecific life history differences described here appear insufficient to produce consistent differences in gene flow patterns. [source] Biogeography and microhabitat variation in temperate algal-invertebrate symbioses: zooxanthellae and zoochlorellae in two Pacific intertidal sea anemones, Anthopleura elegantissima and A. xanthogrammicaINVERTEBRATE BIOLOGY, Issue 2 2000David Secord Abstract. Temperate sea anemones in the genus Anthopleura are unique among cnidarians in harboring two phylogenetically distinct symbiotic algae, zooxanthellae (golden-brown dinophytes, Symbiodinium) and zoochlorellae (green chlorophytes). To determine whether their physiological differences generate patterns in anemone habitat and biogeographic distribution, we sampled symbiotic algae in the small clonal A. elegantissima and the large solitary A. xanthogrammica at 8 field sites (and the other large solitary Anthopleura species at one site) spanning 18° of latitude along 2500 km of the Pacific coast of North America. We found that zoochlorellae predominate in low intertidal habitats and northerly latitudes and in A. xanthogrammica, while zooxanthellae constitute the majority of symbionts in high intertidal habitats and more southerly latitudes and in A. elegantissima. These data are consistent with published predictions based on photosynthetic efficiency of the two algae under varied temperature and light regimes in the laboratory. This anemone-algal system provides a potential biological signal of benthic intertidal communities' responses to El Niño events and long-term climate changes in the Pacific. [source] A framework for assessing the biodiversity and fishery aspects of marine reservesJOURNAL OF APPLIED ECOLOGY, Issue 4 2009Phillip S. Levin Summary 1. ,Resource management agencies are often charged with managing natural resources for economic and social goals, while also protecting and conserving biodiversity and ecosystem function. However, this may not always be possible. Ecosystem-based management is frequently suggested as a way to achieve multiple objectives in resource management and requires that trade-offs among conflicting objectives be identified and an effective means to utilize these trade-offs developed. 2. ,We examine the relationship between area and species richness in a diverse assemblage of fishes along the US West Coast and then use parameters from this relationship as input for a model that considers trade-offs between fisheries yield and the number of species protected by different management strategies. 3. ,The species,area relationship (S = cAz) for fishes along the US Pacific coast is well described by the relationship S = 16·18A0·226. 4. ,There are nearly linear trade-offs between diversity and yield when fishing effort is low. However, the trade-offs become nonlinear as fishing effort increases and imposing MPAs increases both the conservation and fisheries value of the system when the system is overfished. 5. ,Synthesis and applications. Solving conflicts between fisheries and conservation requires attention as to how conservation benefits accrue as fishing effort is reduced. However, scientists often lack quantitative information about the trade-offs inherent in human activities such as fisheries. The approach we develop here can begin to help frame the questions to be posed and evaluate the likely consequences of different management options. [source] Population structure in the South American tern Sterna hirundinacea in the South Atlantic: two populations with distinct breeding phenologiesJOURNAL OF AVIAN BIOLOGY, Issue 4 2010Patrícia J. Faria The South American tern Sterna hirundinacea is a migratory species for which dispersal, site fidelity and migratory routes are largely unknown. Here, we used five microsatellite loci and 799,bp partial mitochondrial DNA sequences (Cytochrome b and ND2) to investigate the genetic structure of South American terns from the South Atlantic Ocean (Brazilian and Patagonian colonies). Brazilian and Patagonian colonies have two distinct breeding phenologies (austral winter and austral summer, respectively) and are under the influence of different oceanographic features (e.g. Brazil and Falklands/Malvinas ocean currents, respectively), that may promote genetic isolation between populations. Results show that the Atlantic populations are not completely panmictic, nevertheless, contrary to our expectations, low levels of genetic structure were detected between Brazilian and Patagonian colonies. Such low differentiation (despite temporal isolation of the colonies) could be explained by demographic history of these populations coupled with ongoing levels of gene flow. Interestingly, estimations of gene flow through Maximum likelihood and Bayesian approaches has indicated asymmetrical long term and contemporary gene flow from Brazilian to Patagonian colonies, approaching a source,sink metapopulation dynamic. Genetic analysis of other South American tern populations (especially those from the Pacific coast and Falklands,Malvinas Islands) and other seabird species showing similar geographical distribution (e.g. royal tern Thalasseus maximus), are fundamental in gaining a better understanding of the main processes involved in the diversification of seabirds in the southern hemisphere. [source] Testing the abundant-centre hypothesis using intertidal porcelain crabs along the Chilean coast: linking abundance and life-history variationJOURNAL OF BIOGEOGRAPHY, Issue 3 2010Marcelo M. Rivadeneira Abstract Aim, The abundant-centre hypothesis (ACH) is based on the assumption that physiological constraints limit populations at the edges of their distributional range, yet the geographical variation of physiological performance or life-history traits has rarely been examined. Here we examine the applicability of the ACH in a marine system by testing whether physiological predictions are reflected in large-scale variations of life-history traits. Location, The Chilean coast (18°,42° S), encompassing more than 2500 km along the Pacific coast of South America. Methods, Five porcelain crab species (Petrolisthes granulosus, Petrolisthes laevigatus, Petrolisthes tuberculatus, Petrolisthes violaceus and Allopetrolisthes angulosus) were sampled on intertidal boulder beaches at 13 sampling sites. For each species and site we evaluated: (1) relative abundance (density), (2) maximum size, (3) size at maturity, (4) sex ratio, (5) proportion of ovigerous females, and (6) presence of recruits. The shape of the spatial distribution of each trait was evaluated statistically against the prediction of four hypothetical models (normal, ramped-south, ramped-north and abundant-edge). Results, The relative abundance and life-history traits showed different spatial patterns among species. Relative abundance (across sites) was fitted by a normal model in only two species. No model fitted the spatial variation in body size and size at first maturity, which showed a slight but monotonic poleward increase in all species. Sex ratio showed a prominent hump-shaped pattern, with females prevailing in the centre of the ranges and males dominating towards the range boundaries; this pattern was statistically significant in three of the five studied species. The proportion of ovigerous females showed no clear latitudinal trends, and mature individuals were observed across most of the geographical range of the species. However, recruits tended to be absent towards the southern (poleward) boundaries of the distribution. Main conclusions, The ACH does not apply to all species equally. The link between abundance and life-history traits is complex and variable among the porcelain crab species studied. Overall, the observed patterns were consistent with the idea that equatorward boundaries might be controlled by physiological restrictions mainly affecting adult survival, whereas poleward boundaries might be shaped by limitations in reproductive output and larval survival. Our results underline the importance of incorporating ecological, physiological and life-history studies in future tests of the ACH. [source] Biogeography of the nearshore rocky-reef fishes at the southern and Baja California islandsJOURNAL OF BIOGEOGRAPHY, Issue 2 2005Daniel J. Pondella II Abstract Aim, To examine the uniqueness and relationship of islands in the San Diegan Province using reef fishes. Location, Pacific coast of Baja and Southern California. Methods, Quantitative scuba surveys and statistics were used. Between June 2000 and August 2002, the nearshore rocky-reef fishes of eight southern California and Baja California islands were quantitatively surveyed. The islands surveyed were: Santa Cruz, San Nicolas, Santa Barbara, Santa Catalina, San Clemente, North Coronado, San Martin and San Benito. These islands span the latitudinal range of offshore islands within the San Diegan marine province. This regional scale approach provided not only the first quantitative description of rocky-reef fishes at five of these islands, but also allowed comparisons with known biogeographical patterns. Results, Here we discuss the distribution and abundance of 84 conspicuous rocky-reef fishes from 35 families. In general, the richness, diversity and composition of fish assemblages at these islands were found to reflect previously described biogeographical processes. The rocky reef fish assemblages of all islands in the survey were found to be significantly distinctive form each other. Phenetic analyses revealed two clusters. San Clemente, Santa Catalina and North Coronado clustered as a warm-water assemblage in the middle of the San Diegan Province. The remaining islands grouped together as a cold-water assemblage, despite the geographically disjunct position of the islands within this cluster. The relatedness of islands was independent of distance. Examination of the most common fish species at all islands revealed that while some conformed to the north,south trending density distributions predicted by previous investigators, the distribution of others could not be explained by latitude or temperature regimes. No single pattern explained the density of fishes at all islands. Both the rock croaker, Pareques sp., and flag cabrilla, Epinephelus labriformis, were observed at San Benito during these surveys, representing northern range extensions and may be indicators of the warming trend observed in this marine province. Main conclusion, For nearshore rocky-reef fishes, the islands of the San Diegan marine province are distinct and their interrelatedness is independent of the distance between them. [source] Californian mixed-conifer forests under unmanaged fire regimes in the Sierra San Pedro Mártir, Baja California, MexicoJOURNAL OF BIOGEOGRAPHY, Issue 1 2000R. A. Minnich Abstract Aim,This study appraises historical fire regimes for Californian mixed-conifer forests of the Sierra San Pedro Mártir (SSPM). The SSPM represents the last remaining mixed-conifer forest along the Pacific coast still subject to uncontrolled, periodic ground fire. Location,The SSPM is a north,south trending fault bound range, centred on 31°N latitude, 100 km SE of Ensenada, Baja California. Methods,We surveyed forests for composition, population structure, and historical dynamics both spatially and temporally over the past 65 years using repeat aerial photographs and ground sampling. Fire perimeter history was reconstructed based on time-series aerial photographs dating from 1942 to 1991 and interpretable back to 1925. A total of 256 1-ha sites randomly selected from aerial photographs were examined along a chronosequence for density and cover of canopy trees, density of snags and downed logs, and cover of non-conifer trees and shrubs. Twenty-four stands were sampled on-the-ground by a point-centred quarter method which yielded data on tree density, basal area, frequency, importance value, and shrub and herb cover. Results,Forests experience moderately intense understory fires that range in size to 6400 ha, as well as numerous smaller, low intensity burns with low cumulative spatial extent. SSPM forests average 25,45% cover and 65,145 trees per ha. Sapling densities were two to three times that of overstory trees. Size-age distributions of trees , 4 cm dbh indicate multi-age stands with steady-state dynamics. Stands are similar to Californian mixed conifer forests prior to the imposition of fire suppression policy. Livestock grazing does not appear to be suppressing conifer regeneration. Main conclusions,Our spatially-based reconstruction shows the open forest structure in SSPM to be a product of infrequent, intense surface fires with fire rotation periods of 52 years, rather than frequent, low intensity fires at intervals of 4,20 years proposed from California fire-scar dendrochronology (FSD) studies. Ground fires in SSPM were intense enough to kill pole-size trees and a significant number of overstory trees. We attribute long fire intervals to the gradual build-up of subcontinuous shrub cover, conifer recruitment and litter accumulation. Differences from photo interpretation and FSD estimates are due to assumptions made with respect to site-based (point) sampling of fire, and nonfractal fire intensities along fire size frequency distributions. Fire return intervals determined by FSD give undue importance to local burns which collectively use up little fuel, cover little area, and have little demographic impact on forests. [source] Morphometric convergence and molecular divergence: the taxonomic status and evolutionary history of Gymnura crebripunctata and Gymnura marmorata in the eastern Pacific OceanJOURNAL OF FISH BIOLOGY, Issue 4 2009W.D. Smith To clarify the taxonomic status of Gymnura crebripunctata and Gymnura marmorata, the extent of morphological and nucleotide variation between these nominal species was examined using multivariate morphological and mitochondrial DNA comparisons of the same characters with congeneric species. Discriminant analysis of 21 morphometric variables from four species (G. crebripunctata, G. marmorata, Gymnura micrura and Gymnura poecilura) successfully distinguished species groupings. Classification success of eastern Pacific species improved further when specimens were grouped by species and sex. Discriminant analysis of size-corrected data generated species assignments that were consistently accurate in separating the two species (100% jackknifed assignment success). Nasal curtain length was identified as the character which contributed the most to discrimination of the two species. Sexual dimorphism was evident in several characters that have previously been relied upon to distinguish G. crebripunctata from G. marmorata. A previously unreported feature, the absence of a tail spine in G. crebripunctata, provides an improved method of field identification between these species. Phylogenetic and genetic distance analyses based on 698 base pairs of the mitochondrial cytochrome b gene indicate that G. crebripunctata and G. marmorata form highly divergent lineages, supporting their validity as distinct species. The closely related batoid Aetoplatea zonura clustered within the Gymnura clade, indicating that it may not represent a valid genus. Strong population structuring (overall ,ST = 0·81,P < 0·01) was evident between G. marmorata from the Pacific coast of the Baja California peninsula and the Gulf of California, supporting the designation of distinct management units in these regions. [source] Phenotypic variation among populations of Atherinops affinis(Atherinopsidae) with insights from a geometric morphometric analysisJOURNAL OF FISH BIOLOGY, Issue 4 2004K. M. O'Reilly Morphological character variation was examined in Atherinops affinis, a temperate marine silverside with a broad geographic range and presumed limited powers of dispersal. Populations of this species were sampled from three California mainland sites, one Channel Island site and one site in the upper Gulf of California. A geometric morphometric analysis yielded higher resolution in the assessment of phenotypic divergence among the four Pacific coast populations than either body measurement or meristic analysis, and it showed that most of the shape variation among these populations occurs in the head region and body depth of the fish. All three analyses supported the hypothesis that populations of A. affinis from central and southern California coastal waters and from Santa Catalina Island are morphologically distinct from each other; the Santa Catalina Island population was found to be the most divergent. On the basis of meristic characters alone, the population of A. affinis from the upper Gulf of California was different from A. affinis populations along the Pacific coast of California. The analyses revealed variation in several morphological characters, e.g. body depth and meristics, known to vary in association with environmental conditions. Given that A. affinis appears to have low among-population genetic variation, this species may be phenotypically plastic in response to the environmental conditions of the habitat of each population. [source] HABITAT DIFFERENCES IN THE TIMING OF REPRODUCTION OF THE INVASIVE ALGA SARGASSUM MUTICUM (PHAEOPHYTA, SARGASSACEAE) OVER TIDAL AND LUNAR CYCLES,JOURNAL OF PHYCOLOGY, Issue 1 2009Carla Monteiro Sargassum muticum (Yendo) Fensholt is an invasive species that is firmly established on intertidal and subtidal rocky shores of Europe and the Pacific coast of North America. Local success and spread of S. muticum is thought to rely on its reproductive potential that seems dependent on exogenous factors like tidal and lunar cycles. This study is the first to compare the reproductive patterns (periodicity of egg expulsion and embryo settlement) of this invader in two different habitats: the middle and low intertidal. The combination of monthly, daily, and tidal samples at triplicate sites within each habitat showed a semilunar periodicity of egg expulsion and embryo settlement coincident with increasing tidal amplitude just before full and new moons. In both habitats, duration of each egg expulsion event was ,1 week, and embryo settlement occurred during the first daily low tide and with the incoming high tide during spring tides. However, both expulsion and settlement started 1,2 d earlier, expulsion saturation was faster, and settlement was higher in the mid- compared to the low intertidal. Our results suggest that the exact timing of gamete expulsion and embryo release of S. muticum responds to local factors, including tidal cues, which result in differences between mid- and low-intertidal habitats. [source] GENE SEQUENCE DIVERSITY AND THE PHYLOGENETIC POSITION OF ALGAE ASSIGNED TO THE GENERA PHAEOPHILA AND OCHLOCHAETE (ULVOPHYCEAE, CHLOROPHYTA),JOURNAL OF PHYCOLOGY, Issue 4 2004Charles J. O'Kelly The phylogenetic position of microfilamentous marine green algae assigned to the species Phaeophila dendroides, Entocladia tenuis (Phaeophila tenuis, and Ochlochaete hystrix was examined through phylogenetic analyses of nuclear-encoded small subunit rDNA and chloroplast-encoded tufA gene sequences. These analyses placed the P. dendroides strains within the Ulvophyceae, at the base of a clade that contains representatives of the families Ulvaceae, Ulvellaceae, and the species Bolbocoleon piliferum, supporting an earlier hypothesis that P. dendroides constitutes a distinct lineage. Substantial divergence in both nuclear and plastid DNA sequences exists among strains of P. dendroides from different geographic localities, but these isolated strains are morphologically indistinguishable. The lineage may have an accelerated rate of gene sequence evolution relative to other microfilamentous marine green algae. Entocladia tenuis and O. hystrix are placed neither in the P. dendroides clade nor in the Ulvellaceae as previous taxonomic schemes predicted but instead form a new clade or clades at the base of the Ulvaceae. Ruthnielsenia gen. nov. is proposed to accommodate Kylin's species, which cannot be placed in Entocladia (=Acrochaete), Phaeophila, or Ochlochaete. Ruthnielsenia tenuis (Kylin) comb. nov., previously known only from Atlantic coasts, is reported for the first time from the Pacific coast of North America (San Juan Island, WA, USA). Isolates of R. tenuis from the Atlantic and Pacific coasts of North America have identical small subunit rDNA and tufA gene sequences. [source] Seasonal changes of antioxidant and oxidative parameters in the coral Pocillopora capitata on the Pacific coast of MexicoMARINE ECOLOGY, Issue 3 2010Marco A. Liñán-Cabello Abstract The physiological responses of the coral Pocillopora capitata to environmental conditions common in winter and summer were studied in 2007 during February,March (winter) and June,July (summer) at La Boquita reef (Manzanillo, Colima, Mexico). Shallow and deep sampling stations were established at different distances from a small jetty built next to the Juluapan Lagoon. We analyzed superoxide radicals () and lipid peroxidants (TBARS); the activities of superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), glutathione reductase (GR), and glutathione-S-transferase (GST); chlorophyll a (Chl a), zooxanthellae density (ZD); and mycosporine-like amino acids (MAAs). Our results showed that the , TBARS, CAT, GST, MAAs, and Chl a, levels were significantly higher in summer (P < 0.05); no seasonal difference was found for GPx, GR or ZD. We found significant differences (P < 0.05) in winter only for Chl a and ZD at shallow sites and, in contrast, for at deeper sites. The results of this study indicate that increasing temperature and radiation associated with seasonal changes (from winter to summer), the efficiency of the enzymes GST, CR and GPX, and the production of MAAs together form a powerful mechanism for P. capitata to offset the detrimental effects of environmental change. [source] Stomach contents of mass-stranded short-finned pilot whales (Globicephala macrorhynchus) from North CarolinaMARINE MAMMAL SCIENCE, Issue 2 2008Vanessa J. Mintzer Abstract We examined the stomach contents of 27 short-finned pilot whales (Globicephala macrorhynchus) that mass stranded on the North Carolina coast on 15 January 2005. Eleven whales had prey parts in their forestomachs. We used frequency of occurrence and numerical abundance to assess the relative importance of prey. Brachioteuthis riisei (numerical abundance 28%), an oceanic species, was the most important cephalopod prey, but Taonius pavo (12%) and Histioteuthis reversa (9%) also represented a substantial part of the diet. A large number of otoliths belonging to the fish Scopelogadus beanii were present (25%). These results differ from reports of the stomach contents of short-finned pilot whales from the Pacific coast in which neritic species dominate the diet. Our findings also suggest that there is a considerable difference between the diet of short- and long-finned pilot whales (Globicephala melas) in the western North Atlantic. The latter feed predominantly on the long-finned squid (Loligo pealei) whereas the former feed on deep-water species. Our results indicate the whales fed primarily off the continental shelf prior to stranding. [source] | ||||||||||||||||||||||||||||||||||||||||