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Southern Areas (southern + area)
Selected AbstractsAbundance and distribution of endangered Franciscana dolphins in Argentine waters and conservation implicationsMARINE MAMMAL SCIENCE, Issue 1 2010Enrique A. Crespo Abstract This is the first study in Argentine waters on the abundance of the threatened Franciscana dolphin, Pontoporia blainvillei. During 2003,2004 we carried out 17 aerial surveys using line transect sampling methodology. We observed 101 Franciscanas in 71 sightings. In northern areas density was estimated at 0.106 individual/km2. Density was lower in southern areas (0.055/km2) and declined with depth beyond 30-m isobaths (0.05/km2). A correction factor for submerged dolphins was applied to density and then extrapolated to the strip between the coastline and the 30-m isobath. Abundance in the northern area was estimated at 8,279 (4,904,13,960) individuals, while in the southern area it was estimated at 5,896 (1,928,17,999) individuals. Considering an annual mortality of about 500,800 individuals, about 3.5%,5.6% of the stock may be removed each year by the fishery and over the 2% recommended by the International Whaling Commission (IWC) and may not be sustainable by the population. Higher densities in coastal areas make Franciscanas more vulnerable to coastal fishing camps, which increased mortality in recent years. A remarkable finding was that while density decreases to the south, values of catch per unit effort (CPUE) increases, indicating different catchability of dolphins between areas. [source] Epidemics of type 1 diabetes in ChinaPEDIATRIC DIABETES, Issue 3 2005Ze Yang Objective:, The aim of this study was to search for the seasonal and geographic variations in epidemics of type 1 diabetes in China. Research design and methods:, Incidence data from 22 type 1 diabetes registration centers across China were analyzed. A Poisson regression model with a sine wave function was applied to evaluate the seasonal trends. A scan statistic was used to examine the occurrence of an epidemic. Results:, There was a significant cyclic trend of incidence of type 1 diabetes in China. The northern area had a higher incidence rate than the southern area. Epidemics were discovered in Dalian and Shenyang from late 1992 to late 1993. Conclusions:, There was a strong association of climate and incidence of type 1 diabetes in China, whereby the incidence was higher in the colder areas and in the winter months. Evidence of epidemics existed in two centers in 1992,1993. It is critical to identify the epidemics early and determine the causes of epidemics. [source] Space,time patterns of co-variation of biodiversity and primary production in phytoplankton guilds of coastal marine environmentsAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 6 2003Maria Rosaria Vadrucci Abstract 1.The relevance of biodiversity to ecosystem processes is a major topic in ecology. Here, we analyse the relationship between biodiversity and productivity of the nano- and micro-phytoplankton guilds in coastal marine ecosystems. 2.The patterns of variation of species richness, diversity and primary productivity (as 14C assimilation) were studied in two marine areas: a eutrophic,mesotrophic area beside the River Po delta (northern Adriatic) and an oligotrophic area around the Salento peninsula (southern Adriatic,Ionian). The study was carried out at 23 sites in the northern area and at 45 sites in the southern area. Sites were arranged on expected spatial and temporal gradients of primary productivity variation, according to distance from the coast, optical depths and seasonal period. 3.167 taxa were identified in the northern area and 153 taxa in the southern area. In both areas, the taxonomic composition of the nano- and micro-phytoplankton guilds exhibited greater temporal than spatial variation. The latter was much higher in the southern area than in the northern area (average dissimilarity between stations being 70.7±0.8% and 44.7±4.2% respectively). 4.Primary productivity varied in space and time on the gradients considered. Phytoplankton species richness and diversity exhibited significant patterns of variation in space and time; overall, these were inversely related to the primary productivity patterns in the northern area, whereas they were directly related in the southern area. 5.The small individual size and the high turnover rate of phytoplankton are likely to underlie the observed relationships, which emphasized a threshold response to nutrient enrichment in agreement with the ,paradox of enrichment'. Under resource enrichment conditions, the high turnover of producers leads to hierarchical partitioning of the available resources with an increasing dominance of a few species. Therefore, the relationship observed here seems likely to be explained by the complementarity hypothesis. Copyright © 2003 John Wiley & Sons, Ltd. [source] Allozyme diversity and history of distribution expansion in the maritime perennial plant Hedyotis strigulosa (Rubiaceae), distributed over the wide latitudes in the Japanese ArchipelagoBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 4 2008MASAYUKI MAKI Allozyme diversity was examined in 30 populations of the maritime perennial plant Hedyotis strigulosa var. parviflora, which is distributed from subtropical islands to the central mainland of Japan. Genetic diversity within populations tended to be larger in southern island populations than in northern mainland populations. In the southern part of the distribution, the population size is generally large and populations are distributed more continuously than in the northern area, resulting in the larger effective size of southern populations as a whole. These factors play a major role in maintaining greater genetic diversity in the southern populations. By contrast, genetic diversity in the northern populations is very low, probably resulting from bottlenecks of population establishments during recolonization from refugial area to the northern areas. Geographically close populations were located near each other in the multidimensional scaling and the phenogram based on genetic distances, suggesting that gene flow among remote populations is rather limited. The pattern of genetic diversity in H. strigulosa var. parviflora is likely caused by the distribution expansion of the species; in the last glacier era, the species was restricted to the southern area; its advance to the northern area is relatively recent. Another variety endemic only to the Daito Islands, H. strigulosa var. luxurians, has lower genetic diversity than H. strigulosa var. parviflora and has genetically diverged from H. strigulosa var. parviflora. © 2008 The Linnean Society of London, Biological Journal of the Linnean Society, 2008, 93, 679,688. [source] Mangrove Distribution during the Holocene in Tribugí Gulf, Colombia,BIOTROPICA, Issue 1 2000Carlos Jaramillo ABSTRACT Neotropical mangrove ecosystems have undergone drastic changes in terms of extension and floristic composition during Plio,Pleistocene times. It is unclear if the northern Pacific coast of Colombia has been occupied continuously by mangroves during the last 5000 years, or if their presence is a recent phenomenon. Two basic questions were asked: (1) is the establishment of mangroves recent?; and (2) what were the dominant floral taxa during the late Holocene? In the Gulf of Tribugí, northern Colombian Pacific, 22 sediment cores were drilled to a maximum depth of 2 m in a diverse suite of mangrove substrates and positions relative to the shoreline. Data were gathered from sedimentological descriptions, palynological analyses, and radiocarbon dating of these cores. During the last 4500 years, mangroves in the southern area of the Tribugí Gulf have remained floristically stable and dominated by Rhizophora. The abundant presence of Acrostichum aureum is recent, probably related to human activities. In contrast, two areas in the northern part of the Gulf show a different history. In the first area, the establishment of mangrove has been relatively recent (ca 2600 yr), probably a result of local subsidence due to tectonic faulting; this mangrove forest was and is dominated by Pelliciem rhizophorae. In the second area, mangrove pollen was not found in sediments younger than 2500 years, suggesting that the scarce presence of mangrove in the area is a result of recent colonization, and not due to logging as previously thought. RESUMEN Ecosistemas Neotropicales de manglar han sufrido cambios dramáticos tanto en su extensión como en su composición florística asociados con cambios climáticos y variaciories del nivel del mar durante el Plio-Pleistoceno. No es claro si la costa norte del Pacífico Colombiano ha sido ocupada por manglares durante los últimos 5000 años. Quisimos responder dos preguncas básicas: Es el establecimiento del manglar un fenómeno reciente? y Cuales fueron las especies que dominaron el mangle durante el Holoceno? Para responder estas preguntas extrajimos 22 corazones de sedimento cn el Golfo de Tribugá, costa norte del Pacífico Colombiano. Los corazones, de máximo dos metros de profundidad, fueron analizados con méttodos palinológicos, sedimentológicos y dataciones radiométricas. El tipo de sedimento más común fué lodo arenoso verde altamente bioperturbado por actividad infaunal. Los manglares mostraron ser muy estables y doniinados por Rhizophora en la mayoría de los sitios estudiados, con excepción de los manglares en la Chunga (Utría) y El Valle. Allí 10s manglares se establecieron recientemente. En la Chunga, un ascenso relativo del nivel del mar hace aproximadamente 2600 años a.p., probablemente local y asociado con la falla de Utría, posibilitó la colonización del sustrato por Pelliciera rhizophorae; es incierto determinar si este ascenso aún se esta produciendo. En el Valle, el escaso establecimiento del manglar es un proceso reciente de colonización y no una reducción en la cobertura del manglar producto de actividades humanas como previamente se asumía. [source] Reconciling differences in trophic control in mid-latitude marine ecosystemsECOLOGY LETTERS, Issue 10 2006Kenneth T. Frank Abstract The dependence of long-term fishery yields on primary productivity, largely based on cross-system comparisons and without reference to the potential dynamic character of this relationship, has long been considered strong evidence for bottom-up control in marine systems. We examined time series of intensive empirical observations from nine heavily exploited regions in the western North Atlantic and find evidence of spatial variance of trophic control. Top-down control dominated in northern areas, the dynamics evolved from bottom-up to top-down in an intermediate region, and bottom-up control governed the southern areas. A simplified, trophic control diagram was developed accounting for top-down and bottom-up forcing within a larger region whose base state dynamics are bottom-up and can accommodate time-varying dynamics. Species diversity and ocean temperature co-varied, being relatively high in southern areas and lower in the north, mirroring the shifting pattern of trophic control. A combination of compensatory population dynamics and accelerated demographic rates in southern areas seems to account for the greater stability of the predator species complex in this region. [source] Use of tag data to compare growth rates of Atlantic coast striped bass stocksFISHERIES MANAGEMENT & ECOLOGY, Issue 5 2003S. A. Welsh Abstract Migratory stocks of Atlantic coast striped bass, Morone saxatilis (Walbaum), range primarily from North Carolina (NC) northward to Canadian waters. Between 1986 and 2000, 267 045 wild striped bass were tagged and released from NC to Massachusetts as part of the Cooperative Striped Bass Tagging Program. Direct measurements of growth of individual fish can be obtained from tag data and are useful for understanding the dynamics of fish populations. Growth rates from regressions of length-increment vs. time-at-liberty were estimated for striped bass tagged and released in three southern states [NC, Virginia (VA) and Maryland (MD)] and three northern states (New Jersey, New York and Rhode Island). Striped bass tagged in waters of northern states grew faster (significantly steeper regression slopes) than those tagged in southern areas. Migratory patterns, stock mixing, and unmeasured biotic and abiotic influences on growth precluded conclusions that observed growth patterns are stock-specific. These results, however, indicate latitudinal differences in growth rates, and should be considered in future research and management of Atlantic coast striped bass. [source] Groundfish species diversity and assemblage structure in Icelandic waters during recent years of warmingFISHERIES OCEANOGRAPHY, Issue 1 2010LILJA STEFANSDOTTIR Abstract Elevated ocean temperatures have been predicted to lead to a poleward shift in the latitudinal distribution ranges of fish species. Different responses of fish species to increased temperatures might lead to changes in assemblage structure and local species richness. In this study, the assemblage structure and diversity of groundfish in Icelandic waters were examined using data from a standardized groundfish survey conducted annually in 1996,2007. We used hierarchical cluster analysis to define assemblages in two time periods and canonical correspondence analysis to explore the relationships between the assemblages and temperature, depth, latitude, longitude and year. We further used two estimates of diversity, species richness and the Shannon index. Four major species assemblages were identified. Assemblages in the hydrographically stable deep waters north of the country were consistent during the study, while assemblage structure in the more variable shallow waters underwent some changes. For this period of generally increasing sea temperature, the canonical correspondence analysis also revealed a shift towards species representative of warmer temperatures. Diversity was shown to be highly variable both temporally and spatially, and also to vary with depth and temperature. Species richness increased with temperature and time southwest of the country, but decreased northeast of the country. The different trends detected between the northern and southern areas illustrate the importance of performing analyses at the most appropriate scale. [source] Biodiversity of Belgian groundwater fauna in relation to environmental conditionsFRESHWATER BIOLOGY, Issue 4 2009PATRICK MARTIN Summary 1. The Pleistocene glaciations during the Quaternary appear to have resulted in an impoverished groundwater fauna in northern Europe. Re-colonisation may have occurred either through long-distance dispersal from unglaciated southern areas or from local refugia. 2. The Belgian groundwater fauna was sampled at multiple sites, and its habitats characterised, to assess whether the composition of present-day stygobiotic assemblages can be attributed to either of these mechanisms. 3. A total of 202 sampling sites were selected in four hydrogeographic units of the Meuse River catchment. Sites were equally divided among the saturated and unsaturated zones of fractured aquifers (karst) and within the hyporheic and phreatic zones of porous aquifers. Seventeen environmental parameters were determined in parallel. 4. More than 140 species were recorded, including representatives of the Amphipoda, Cladocera, Copepoda, Hydrachnidia, Isopoda, Oligochaeta, Ostracoda, Mollusca, Syncarida and Nematoda. Thirty stygobiont species were identified, of which 10 species were new to the Belgian fauna, raising the total number of stygobiotic species in Belgium to 41. 5. The frequency of occurrences of stygobiotic species was always low, with 37% of the sampled sites lacking stygobionts. A few species were exclusive to one hydrological zone, although no statistically significant differences were detected in species richness at any of the four hierarchial levels considered (Meuse catchment = region, hydrogeographic units, aquifer type and hydrological zone). 6. Overall, results suggest that the stygobiotic fauna of Belgium is species-poor and mostly comprises widely distributed species with broad ecological tolerances. This supports the view that eurytopic species re-colonised the area by long-distance dispersal from refugia in southern Europe. The virtual absence of endemic species further suggests that the scenario of an ancient fauna that survived in local refugia is of minor importance. [source] Abundance and distribution of endangered Franciscana dolphins in Argentine waters and conservation implicationsMARINE MAMMAL SCIENCE, Issue 1 2010Enrique A. Crespo Abstract This is the first study in Argentine waters on the abundance of the threatened Franciscana dolphin, Pontoporia blainvillei. During 2003,2004 we carried out 17 aerial surveys using line transect sampling methodology. We observed 101 Franciscanas in 71 sightings. In northern areas density was estimated at 0.106 individual/km2. Density was lower in southern areas (0.055/km2) and declined with depth beyond 30-m isobaths (0.05/km2). A correction factor for submerged dolphins was applied to density and then extrapolated to the strip between the coastline and the 30-m isobath. Abundance in the northern area was estimated at 8,279 (4,904,13,960) individuals, while in the southern area it was estimated at 5,896 (1,928,17,999) individuals. Considering an annual mortality of about 500,800 individuals, about 3.5%,5.6% of the stock may be removed each year by the fishery and over the 2% recommended by the International Whaling Commission (IWC) and may not be sustainable by the population. Higher densities in coastal areas make Franciscanas more vulnerable to coastal fishing camps, which increased mortality in recent years. A remarkable finding was that while density decreases to the south, values of catch per unit effort (CPUE) increases, indicating different catchability of dolphins between areas. [source] SPOTTED DOLPHIN EVASIVE RESPONSE IN RELATION TO FISHING EFFORTMARINE MAMMAL SCIENCE, Issue 1 2005Cleridy E. Lennert-Cody Abstract Spotted dolphins in the eastern Pacific Ocean associate with yellowfin tuna. During the chase and encirclement phases of purse-seining for tunas, dolphin attempt to evade encirclement with the purse-seine net. We used data on evasive behavior (1982,2001) and numbers of purse-seine sets (1959,2001) to study the relationship between evasion and fishing effort. Results show that in nearshore areas first exploited by the fishery in the early 1960s, dolphins exhibited high evasion, but with a limited correlation between evasion and cumulative effort. In areas farther offshore next exploited in the mid-to late-1960s, dolphins showed high evasion and a significant correlation between evasion and cumulative effort. Dolphins in far-western and southern areas, first exploited in the late 1960s to early 1970s, exhibited low evasion, with little relationship to cumulative effort. We hypothesize that this spatial pattern is the result of two types of pressure from fishing: early effort in nearshore areas with a high risk of mortality that generated a lasting evasive response, followed by a longer period of even greater effort but with lower risk of mortality that generated evasion by longer-term learning. [source] New Zealand phylogeography: evolution on a small continentMOLECULAR ECOLOGY, Issue 17 2009GRAHAM P. WALLIS Abstract New Zealand has long been a conundrum to biogeographers, possessing as it does geophysical and biotic features characteristic of both an island and a continent. This schism is reflected in provocative debate among dispersalist, vicariance biogeographic and panbiogeographic schools. A strong history in biogeography has spawned many hypotheses, which have begun to be addressed by a flood of molecular analyses. The time is now ripe to synthesize these findings on a background of geological and ecological knowledge. It has become increasingly apparent that most of the biota of New Zealand has links with other southern lands (particularly Australia) that are much more recent than the breakup of Gondwana. A compilation of molecular phylogenetic analyses of ca 100 plant and animal groups reveals that only 10% of these are even plausibly of archaic origin dating to the vicariant splitting of Zealandia from Gondwana. Effects of lineage extinction and lack of good calibrations in many cases strongly suggest that the actual proportion is even lower, in keeping with extensive Oligocene inundation of Zealandia. A wide compilation of papers covering phylogeographic structuring of terrestrial, freshwater and marine species shows some patterns emerging. These include: east,west splits across the Southern Alps, east,west splits across North Island, north,south splits across South Island, star phylogenies of southern mountain isolates, spread from northern, central and southern areas of high endemism, and recent recolonization (postvolcanic and anthropogenic). Excepting the last of these, most of these patterns seem to date to late Pliocene, coinciding with the rapid uplift of the Southern Alps. The diversity of New Zealand geological processes (sinking, uplift, tilting, sea level change, erosion, volcanism, glaciation) has produced numerous patterns, making generalizations difficult. Many species maintain pre-Pleistocene lineages, with phylogeographic structuring more similar to the Mediterranean region than northern Europe. This structure reflects the fact that glaciation was far from ubiquitous, despite the topography. Intriguingly, then, origins of the flora and fauna are island-like, whereas phylogeographic structure often reflects continental geological processes. [source] Sea turtle strandings reveal high anthropogenic mortality in Italian watersAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 6 2010Paolo Casale Abstract 1.Spatio-temporal distribution and anthropogenic mortality factors were investigated in loggerhead turtles (Caretta caretta) found stranded or floating in the waters around Italy. A total of 5938 records for the period 1980,2008 were analysed concerning loggerhead turtles measuring from 3.8 to 97,cm curved carapace length (mean: 48.3,cm). 2.Results highlighted the following conservation issues: (i) in the study area, anthropogenic mortality is higher than natural mortality; (ii) interaction with fisheries is by far the most important anthropogenic mortality factor; (iii) longlines are an important mortality factor in the southern areas; (iv) trawlers are the cause of high numbers of dead strandings in the north Adriatic; (v) entanglement in ghost-gear or in other anthropogenic debris affects high numbers of turtles; and (vi) boat strikes are an important source of mortality in most areas but mostly in the warm seasons. 3.Results also indicate that: (vii) the north Adriatic is the area with the highest turtle density; and (viii) the south Adriatic and to a lesser extent the surrounding areas of the north Adriatic and the Ionian, are important developmental areas for loggerhead turtles in the first years of life. 4.Italy is in the centre of the Mediterranean Sea and borders major foraging areas for the loggerhead turtles in the region, and these results confirm previous concerns about the level of anthropogenic mortality in Italian waters. Copyright © 2010 John Wiley & Sons, Ltd. [source] | ||||||||||||||||||||||