Introgression in peripheral populations and colonization shape the genetic structure of the coastal shrub Armeria pungens

The coastal shrub Armeria pungens has a disjunct Atlantic-Mediterranean distribution. The historic range expansion underlying this distribution was investigated using the nuclear internal transcribed spacer region, three plastid regions (namely trnL-F, trnS-fM and matK) and morphometric data. A highly diverse ancestral lineage was identified in southwest Portugal. More recently, two areas have been colonized: (1) Corsica and Sardinia, where disjunct Mediterranean populations have been established as a result of the long-distance dispersal of Portuguese genotypes, and (2) the southern part of the Atlantic range, Gulf of Cadiz, where a distinct lineage showing no genetic differentiation among populations occurs. Genetic consequences of colonization seem to have been more severe in the Gulf of Cadiz than in Corsica-Sardinia. Although significant genetic divergence is associated with low plastid diversity in the Gulf of Cadiz, in Corsica-Sardinia, the loss of plastid haplotypes was not accompanied by divergence from disjunct Portuguese source populations. In addition, in its northernmost and southernmost populations, A. pungens exhibited evidence for ancient or ongoing introgression from sympatric congeners. Introgression might have created novel genotypes able to expand beyond the latitudinal margins of the species or, alternatively, these genotypes may be the result of surfing of alleles from other species in demographic equilibrium into peripheral populations of A. pungens. Our results highlight the evolutionary significance of genetic drift following the colonization of new areas and the key role of introgression in range expansion.     

Cephalopod paralarvae and upwelling conditions off Galician waters (NW Spain)

A total of 103 cephalopod paralarvae were sampled during June 1995 in Galician waters (NW Spain). Samples were taken with Bongo nets of 300 and 500 m mesh size at 48 sampling stations along 10 transverse transects ranging from 80 to 600 m water depth. Paralarvae of loliginid squid were most abundant (40%). The Rhynchoteuthion paralarvae of ommastrephid squid accounted for 25%, whereas sepiolids comprised 23% of the total sample. Octopods were scarce, at only 6.6%. Other cephalopod families accounted for 5%. Sizes of paralarvae ranged from 1.0 to 7.1 mm mantle length. Temperature and salinity distribution showed the presence of an intense upwelling during the survey period. The sampling data obtained before and during the presence of upwelled water off Rias of Pontevedra and Vigo (southern zone) showed that paralarval cephalopod abundance and distribution were closely related to the upwelled Eastern North-Atlantic Central Water (ENACW).      

Coccolithus pelagicus, a productivity proxy related to moderate fronts off Western Iberia

The traditional interpretation of Coccolithus pelagicus as a cold water proxy is examined based on its distribution patterns in the water column off the Portuguese coast (using data from eleven cruises) and in Holocene surface sediment samples and Quaternary cores from the same region.Coccolithus pelagicus is common in the Portuguese upwelling system, an area where surface waters are predominantly of subtropical origin. Although revealing an affinity for low temperature upwelled waters, the species was found in waters up to 18°C associated with riverine plume and shelf-break fronts. C. pelagicus seemed to consistently occupy a particular ecological niche, between other phytoplankton groups, related to moderate turbulence conditions combined with nutrient availability. From this behaviour, it is proposed that C. pelagicus can be used as a tracer of the periphery of areas of enhanced productivity.Coccolithus pelagicus preferences for fronts of moderate temperature and salinity gradients are tentatively used to explain particular features of its sedimentary record. The repeated increase of C. pelagicus in thanatocoenoses (surface sediment assemblages) close to three river mouths, on the Portuguese shelf, are interpreted as a positive response to the development of riverine plumes. On the other hand, inconsistencies in the correlation between sea surface cooler-glacial and warmer-interglacial isotope stages and the relative abundance pattern of C. pelagicus during the Late Quaternary, as registered in two Galicia Bank piston cores (42°N), are tentatively explained in terms of shifts in the extent of the outer limit of the local palaeoproductivity belt off the Iberian Peninsula.     

Ecology matters: Atlantic-Mediterranean disjunction in the sand-dune shrub Armeria pungens (Plumbaginaceae)

Inferring the evolutionary history of Mediterranean plant lineages from current genetic, distributional and taxonomic patterns is complex because of a number of palaeoclimatic and geological interconnected factors together with landscape heterogeneity and human influence. Therefore, choosing spatially simplified systems as study groups is a suitable approach. An amplified fragment length polymorphism (AFLP) study using two restriction enzyme combinations (EcoRI/MseI and KpnI/MseI) was carried out to estimate the structure of genetic variation throughout the range of Armeria pungens. This species has a West Iberian-Corso/Sardinian disjunct distribution on coastal sand-dune ecosystems. Bayesian, amova and genetic distance analyses of the AFLP data revealed the same distinguishable genetic groups, which do not match the main geographical disjunction. Corso-Sardinian populations were found to be genetically closer to southwest Portuguese than to those from the Gulf of Cadiz (the closest geographically). Eastwards long-distance dispersal is therefore invoked to explain this geographical disjunction. A GIS analysis based on bioclimatic envelope modelling aiming to characterize the current locations of A. pungens found strong similarities between the Portugal and Corsica-Sardinia sites and less so between these areas and the Gulf of Cadiz. This coincident pattern between AFLP and climatic data suggests that the geographical disjunction is better explained by climatic factors than by the likeliness of a stochastic dispersal event. Such a combined phylogeographical-GIS modelling approach proves to be enlightening in reconstructing the evolutionary history of plant species.     

Oceanography of the Gulf of Tehuantepec, Mexico, indicated by Radiolaria remains

The morphology of the Gulf of Tehuantepec, Mexico, is redefined through a bathymetric analysis and this redifinition is considered to explain the distribution patterns of non-carbonate sediments, particularly the radiolarian remains. Although the distribution patterns of pelagic sediments are influenced by the Gulf of Tehuantepec bathymetrical morphology and the terrigenous input, these “reflect” clearly the regional oceanography. Northern strong winds, called the “Tehuanos”, blowing across the sea surface of this Gulf when the Intertropical Convergence is at its southernmost position, define the main sedimentologic dynamics of this region. This wind field gives rise to an oceanic front at the southwestern part of the Gulf, as well as upwelling processes at its central-eastern part. In the mixing at the front there is some contribution of California Current waters, while in the upwelling area there is a large contribution of the tropical-subtropical water which is carried by the Costa Rica Coastal Current. This oceanographic framework controlls the makeup of radiolarian assemblages. Consequently, at the seabottom, under the oceanic front, the presence of the radiolarian species Lithomelissa thoracites and Cycladophora davisiana is observed, while under the upwelling region, Acrosphaera murrayana is conspicuous.     

Distribution of common octopus and common squid paralarvae in a wind-driven upwelling area (Ria of Vigo, northwestern Spain)

The variation of paralarval abundance in a region subjectedto wind-driven upwelling (Ria of Vigo, northwestern Spain) wasstudied. Research cruises were undertaken during the favourableupwelling season (May to October) in 2000 and 2001. Each cruiseincluded biological and hydrographic sampling and consistedof five stations in waters located to the east and west of theCies Islands. A total of 221 paralarvae of Octopodidae and Loliginidaewere collected over the 12-month study period. During 2000,higher abundance of paralarvae was observed in July, Septemberand October for Loligo vulgaris and Octopus vulgaris. In 2001,abundance of both species was higher in May and also in Septemberfor O. vulgaris. The mantle length of the paralarvae variedfrom 1.25 to 2.25 mm and from 1.00 to 4.90 mm within the O.vulgaris and L. vulgaris individuals, respectively. The presence/absenceof upwelling modulates the abundance and spatial distributionof loliginid and octopod paralarvae. The relationship betweenthe distribution and movement of these paralarvae in the Riaof Vigo seems to follow the circulation system defined for thisarea; when the upwelling extends its influence inside the Ria,the paralarvae are transported to the inner part in a west—eastdirection.     

Dinoflagellate cyst distribution in surface sediments along the south-western Mexican coast (14.76° N to 24.75°N)

In this study, we explore the relationship between the modern assemblages of organic-walled dinoflagellate cysts and sea-surface conditions (temperature, salinity, primary productivity) and water depth and distance to the coast. Statistical treatments were performed on 95 surface sediment samples from sites located along the south-western Mexican coast (14.76° N to 24.75°N). Redundancy analysis (RDA) illustrates that the principal parameters correlated with the regional cyst distribution are the distance to the coast and the productivity in the upper water column, which is closely related to upwelling intensity. Empirical observations coupled with RDA provide insight into the spatial coverage of some cyst taxa produced by dinoflagellate species potentially responsible for harmful algal blooms along the coast. They also allow the recognition of four zones of assemblages, which are linked to the upwelling intensity and the productivity and characterize La Paz Bay, the south-western Mexican margin (from 15.95° N to 23.11° N), the northern part of the Gulf of Tehuantepec and the southern part of the Gulf of Tehuantepec.     

Phytoplankton distribution and composition off the coast of Galicia (northwest of Spain)

During October 1977, phytoplankton iamples were collected alongwith other hydrographic and biological data from a grid of stationslocated off Galicia (NW of Spain), between the coast and about100 km offshore. Chlorophyll a distribution and phytoplanktoncomposition were studied and related to hydrographic and geographicfeatures of the area. The higher phytoplankton biomasses werefound off the western coast and were conditioned by the presenceof the rias - flooded tectonic valleys of moderate depth functioningas positive estuaries - and the occurrence of coastal upwelling,which allows the injection of nutrient rich water along thebottom of the rias. The qualitative composition of the phytoplanktonreflected principally the influence of the rias but appearedalso to show variability related to the distribution of watermasses. The patterns of circulation of the surface and sub-surfacewaters were likely to reinforce the phytoplankton differencesbetween the northern and western coasts of Galicia.     

Phytogeography of upwelling areas in the Arabian Sea

Aim The identification of the marine plant communities of two islands from different upwelling areas of the Arabian Sea, with a similar diversity in biotopes. A comparison of the species composition of these macroalgal communities and their biogeographical affinities within the Indian Ocean should give insight into the biogeographical position of the Arabian Sea within the larger Indian Ocean. The incorporation of environmental parameters in the analysis is instructive in understanding their importance in shaping the diverse marine assemblages of the Arabian Sea. Location Arabian Sea: (1) the Socotra Archipelago (Yemen; 12.47° N, 53.87° E) in the Somali upwelling area, (2) Masirah Island (Oman; 20.42° N, 58.79° E) in the upwelling area of the southern Arabian Peninsula. Methods The marine flora of different biotopes around both islands were examined by means of qualitative assessments. Ordination analysis [detrended correspondence analysis (DCA)] was used to identify the different plant communities and to correlate these with environmental parameters. The species composition of the identified communities were compared (tripartite similarity index) and their biogeographical affinity with nations bordering the Indian Ocean was determined. Indicator species analyses were performed to identify the characteristic species of the different plant communities and their biotopes. Results The DCA analysis shows a clustering of sites (plant communities) corresponding with their geographical position, linked in turn to the prevailing environmental conditions of the different coastal areas. The combined interpretation of the ordination, similarity and biogeographical analyses results in the aggregation of similar plant communities of both upwelling areas into four biotopes. Main conclusions The north coast communities of Socotra and the west coast communities of Masirah can be grouped into three biotopes related to the degree of exposure (to upwelling) and sedimentation. These biotopes are typified by indicator species, characteristic for specific substrata, and have a high biogeographical affinity with the East African coast. The plant communities of Socotra's south coast and Masirah's east coast constitute a fourth biotope, being diverse and species rich, typified by a large proportion of red macroalgae including the characteristic species of the unique Arabian Sea flora. This biotope has a pronounced biogeographical affinity with distant regions (disjunctly distributed taxa) as South Africa's East Coast and Western Australia. Within the different biotopes, the communities of Masirah are more divergent from an East African flora in comparison to Socotra, the latter being a stepping stone between the East African and Arabian Sea flora.     

Ecological biogeography of cephalopod molluscs in the Atlantic Ocean: historical and contemporary causes of coastal diversity patterns

Aim One of the most recognized ecological paradigms on earth is the increase in species richness from the poles towards the equator. Here we undertake a comprehensive survey of the latitudinal gradients of species richness (LGSR) of coastal cephalopod fauna in the western (WA) and eastern margins (EA) of the Atlantic Ocean, and test climate and non‐climate theories to explain the variation in diversity. Location The coastal Atlantic Ocean. Methods The diversity and geographical ranges of coastal cephalopods were investigated by means of an exhaustive survey of the primary literature, reports and on‐line data bases. In order to test the productivity, ambient energy and area hypotheses, we investigated the relationship between diversity and net primary production (NPP), sea surface temperature (SST; measure of solar energy input) and continental shelf area, respectively. Results LGSR of cephalopod molluscs are present at both Atlantic coasts, but are quite distinct from each other. Historical processes (rise of the Central American Isthmus, formation of ‘Mare Lago’ and glaciations) explained much of the shape and the zenith of LGSR. Contemporary climate and non‐climate variables also each explained over 83% and 50% of the richness variation in WA and EA, respectively, and the best fitted models accounted for > 92% of the variance. By combining latitude with depth a strong Rapoport effect was observed in WA but not in EA. Main conclusions Besides the evolutionary history, we demonstrate that the contemporary environmental gradients (SST and NPP), shelf area and extent of coral habitat can predict many of the diversity patterns. The longitudinal difference in Rapoport's bathymetric rule is attributed to western fauna specialization to shallow coral reef habitats and greater ecological tolerance of eastern fauna to upwelling ecosystem dynamics. A combined approach of historical biogeography and species–area–energy theories was essential to fully understand broad‐scale variation in cephalopod biodiversity.     

Cephalopods in the diet of the striped dolphin Stenella coeruleoalba from the western Mediterranean during an epizootic in 1990

Fifteen cephalopod species from 28 stomach contents of striped dolphins, Stenella coeruleoalba (Meyen, 1833), stranded during an epizootic on the western Mediterranean coast in summer 1990, were analysed.
Albraliopsis pfefferi, Onychoteuthis banksii, Todarodes sagittatus and Brachioteuthis riisei are species showing higher relative importance indices. Composition and characteristics of cephalopod preys were discussed and compared to the scarce literature for this cetacean. The data showed a mixed diet of muscular and gelatinous body squids, mainly consisting of oceanic and pelagic or bathypelagic species.     

The influence of a coastal upwelling event on chlorophyll <Emphasis Type="Italic">a</Emphasis> and nutrient dynamics in the surface layer of the Gulf of Finland,Baltic Sea

Temporal variation and distribution of chlorophyll a and nutrients concentration was evaluated on the basis of field observations in August 2006 in the Gulf of Finland. Strong easterly winds in August 2006 generated an upwelling event along the Estonian coast of the Gulf of Finland. It caused a drop of the water-surface temperature and nutrient enrichment of the upper layer. At first, the chlorophyll a declined in the area affected by the upwelled water due to the strong advective transport of the chlorophyll a rich waters towards the northern coast and due to the intensive water mixing and low seed population in the upwelling waters. After stabilization of the upwelling, nutrients from the upper mixed layer were consumed fast: there were no nitrites + nitrates left one week later, and phosphate concentration was under the detection limit 2 weeks later. The smaller phytoplankton size fraction showed faster response to the upwelled nutrients compared with the bigger size fraction, showing the increase in chlorophyll a content already during the stabilization of the upwelling. The increase in chlorophyll a concentration in >20-μm size fraction at stations influenced by upwelling was observed only after the relaxation of the upwelling and formation of stratification.     

The American brine shrimp as an exotic invasive species in the western Mediterranean

The hypersaline environments and salterns present in the western Mediterranean region (including Italy, southern France, the Iberian Peninsula and Morocco) contain autochthonous forms of the brine shrimp Artemia, with parthenogenetic diploid and tetraploid strains coexisting with the bisexual species A. salina. Introduced populations of the American brine shrimp A. franciscana have also been recorded in these Mediterranean environments since the 1980s. Based on brine shrimp cyst samples collected in these countries from 1980 until 2002, we were able to establish the present distribution of autochthonous brine shrimps and of A. franciscana, which is shown to be an expanding invasive species. The results obtained show that A. franciscana is now the dominant Artemia species in Portuguese salterns, along the French Mediterranean coast and in Cadiz bay (Spain). Co-occurrence of autochthonous (parthenogenetic) and American brine shrimp populations was observed in Morocco (Mar Chica) and France (Aigues Mortes), whereas A. franciscana was not found in Italian cyst samples. The results suggest these exotic A. franciscana populations originate as intentional or non-intentional inoculations through aquacultural (hatchery effluents) or pet market activities, and suggest that the native species can be rapidly replaced by the exotic species. This revised version was published online in July 2006 with corrections to the Cover Date.     

Radiolaria as indicators of upwelling processes: The Peruvian connection

In the sediments along the coastal region of Peru, certain radiolarian species have preferences to waters associated with upwelling. Such is the case forPolysolenia murrayana in the upwelling areas “fed” by equatorial water and forCenosphaera (?) sp. in the upwelling areas “fed” by temperate (Subantarctic) water.Cycladophora (?)davisiana appears to “frame” the upwelling centers, suggesting that it prefers regions near thermic fronts.The down-core records of these species, as well as records of quartz and organic carbon, are depicted in three¹⁴C andδ¹⁸O dated cores, located along the Pacific coast of South America, between 11° and 13°S. They suggest that both the eolian and oceanic circulation were more intense during the last glacial stage (approximately between 33,000 and 11,000 years ago) than during the present postglacial. At these latitudes, the intensification in circulation was not only accompanied by an increased coastal upwelling and in turn by an increased primary productivity, but also by a larger supply of Temperate waters to the area.     

Chemosymbiotic bivalves from the mud volcanoes of the Gulf of Cadiz, NE Atlantic, with descriptions of new species of Solemyidae, Lucinidae and Vesicomyidae

The chemosymbiotic bivalves collected from the mud volcanoes of the Gulf of Cadiz are reviewed. Of the thirteen species closely associated with chemosynthetic settings two Solemyidae, Solemya (Petrasma) elarraichensissp. n. and Acharax gadiraesp. n., one Lucinidae, Lucinoma asapheussp. n., and one Vesicomyidae, Isorropodon megadesmussp. n. are described and compared to close relatives of their respective families. The biodiversity and distribution of the chemosymbiotic bivalves in the Gulf of Cadiz are discussed and compared to the available information from other cold seeps in the Eastern Atlantic and Mediterranean. Although there is considerable similarity at the genus level between seep/mud volcano fields in the Eastern Atlantic and Mediterranean, there is little overlap at the species level. This indicates a high degree of endemism within chemosymbiotic bivalve assemblages.     

Interspecific variations of otolith chemistry in estuarine fish nurseries

Otolith chemical composition differed between juveniles of five fish species ( Solea solea , Solea senegalensis , Platichthys flesus , Diplodus vulgaris and Dicentrarchus labrax ) in nursery areas of six estuaries along the Portuguese coast (Douro, Ria de Aveiro, Mondego, Tejo, Sado and Mira). Spatially consistent patterns in the concentration of some elements were responsible for differences between species. Discrimination of estuaries using data from all species simultaneously averaged 44·7% of correctly classified cases, whilst discrimination of species averaged 76·2%. Moreover, species-related patterns in otolith fingerprints were highlighted when comparing species for each estuarine nursery area, with intra estuarine species discrimination averages ranging from 86·2 to 100·0%. Similarities in the otolith elemental fingerprints were larger between species with close phylogeny and ecology, particularly between flatfish and perciform species. In addition to the differences in physiological regulation of species, specific microhabitat use in a common environment was suggested as a relevant factor for the differentiation of otolith chemistry among species occurring in the same locations. Despite positive results in specific estuaries, variation in otolith composition limited the use of species as proxies to classify others to their system of origin.     

浙南近海头足类种类组成及生态位分析

在浙南海域布设42个调查站位, 于2015年11月、2016年2月、5月和8月进行了4个航次的系统调查。针对获得的头足类样品, 运用相对重要性指数、生态位宽度和生态位重叠等生态指标, 结合非度量多维标度法(nMDS)和典范对应分析(CCA)对生态位的重叠和分化进行分析。结果表明: 调查海域有头足类14种, 优势种为剑尖枪乌贼、多钩钩腕乌贼、曼氏无针乌贼和火枪乌贼; 生态位变化范围为0.09—7.01, 多钩钩腕乌贼、剑尖枪乌贼、柏氏四盘耳乌贼和火枪乌贼为广生态位种, 四盘耳乌贼、曼氏无针乌贼和田乡枪乌贼为中生态位种, 其余为窄生态位种; 生态位重叠值范围为0.00—0.70, 种间变化较大; 影响头足类分布的最主要因素是悬浮物, 其次为叶绿素和盐度, 温度和溶氧影响相对较小, 这些环境因素综合解释了此区域头足类群落结构83%的总变异。     

Zoogeography of the coral reef fishes of the Socotra Archipelago

Fish communities and habitats were studied at the Socotra archipelago (Gulf of Aden, ≈12°N 54°E). Extensive and unexpected hermatypic coral communities were recorded, at the centre of a 2200 km gap in knowledge of species and habitat distributions which coincides with a change from a western Indian Ocean coral reef fauna to an Arabian one. The fish assemblage associated with the Socotra archipelago corals is predominantly south Arabian. An east African influence, minimal on the mainland coasts of Arabia, is more evident here, and results in previously unrecorded sympatry between Arabian endemic species and their Indian Ocean sister taxa. A study of distributions of Chaetodontidae (butterflyfishes) in the north-western Indian Ocean reveals a number of distinct patterns, with a trend for species replacement along a track from the northern Red Sea to the Indian Ocean. A major feature of the reef fish zoogeography of the region is found to be a distinct south Arabian area, characterized by a 'pseudo-high latitude effect' which results from seasonal cold water upwelling along the Arabian sea coasts of Yemen and Oman and the Indian Ocean coast of Somalia. This south Arabian feature is consistent across a wide range of fish families. It is most pronounced in Oman and Yemen, and although it is the dominant influence at Socotra it is slightly 'diluted' here by the east African influence. The south Arabian area wholly or partly accounts for most of the major marine zoogeographic features around Arabia, and is the principal feature fragmenting Arabian coastal fish assemblages, and separating them from those of the wider Indo-west Pacific.     

Cephalopods in the diet of the South African fur seal (Arctocephalus pusillus pusillus)

The stomach contents of 1522 adult seals ( Arctocephalus pusillus pusillus ) and 673 pups, which were collected around the West and South Coasts of Southern Africa, were examined and cephalopod prey identified. About 20 cephalopod species (some identifications were uncertain) were found in the stomachs, of which only six were significant: Loligo vulgaris reynaudii. Sepia spp., Octopus sp., Todaropsis eblanae, Todarodes angolensis and Ocythoe tuberculata. This list suggests that A. pusillus feeds exclusively on the continental shelf, frequently on or near the bottom. Among adults, cephalopod prey varied in importance around the coast. It was most important on the South Coast of South Africa where it comprised 35.0% of the weight of all prey, of which L. v. veynaudii constituted about 88%. On the West Coast cephalopods comprised about 26.6% by weight of all prey, and Octopus sp. predominated, whereas in Namibian waters cephalopods were least important, constituting only 3.4% by weight of all prey, with Todarodes angolensis and Octopus sp. being most significant. Among pups (aged 8–10 months) in the Lüderitz (Namibia) area, cephalopods were about 16.9% of prey by weight, of which Ocythoe tuberculata , small Sepia spp. and Octopoda were most important.     

Nutrient and phytoplankton dynamics in the Queen Charlotte Islands (Canada) during the summer upwelling seasons of 2001-2002

The Queen Charlotte Islands, Canada, lie at the northern extremeof the coastal upwelling system of the eastern North PacificOcean (51–54°N). In this study, the first observationsof spatial and inter-annual patterns in nutrient inventories,chlorophyll (Chl) a and phytoplankton assemblages are reportedand related to oceanographic conditions in near-shore watersof the island archipelago. Stronger and more persistent upwellingin 2002 coincided with higher nutrient and Chl a standing stockscompared to 2001 and a higher proportion of diatoms. Dinoflagellateswere more prevalent in 2001, including several potentially harmfulspecies. At sub-seasonal scales, Chl a concentrations were greatestduring downwelling conditions and smallest during upwellingconditions. On the west coast, weak water column stratification,high relative proportions of diatoms and large nutrient inventoriesaccompanied upwelling-favourable conditions, whereas on theeast coast, there was no direct relationship between the BakunUpwelling Index and water column stability. According to redundancyanalysis, variability in species composition was best explainedby sea surface temperature, the depth of the euphotic zone andnutrient inventories. The east coast supported blooms of coccolithophoreswithin protected bays, confirming previous satellite observationsthat showed bright patches in these areas. The data illustratethat moderate upwelling can have an important influence on near-shorealgal standing stocks and species composition at the northernextreme of the upwelling system off the west coast of NorthAmerica, and that topographical complexity may be importantfor the development of phytoplankton blooms.