Blitzkrieg in a Marine Invasion: Caulerpa racemosa var. cylindracea (Bryopsidales, Chlorophyta) Reaches the Canary Islands (North-East Atlantic)

On the basis of morphological and genetic studies (rDNA ITS1, 5.8S, ITS2, and a 18S rDNA intron), we confirm here that Caulerpa racemosa var. cylindracea (Sonder) Verlaque, Huisman et Boudouresque, a southwestern Australian taxon recently introduced into the Mediterranean Sea also occurs in the Canary Islands. This is the first report of C. racemosa var. cylindracea in the Atlantic. It was observed for the first time in the Canary Archipelago in 1997–1998. The speed and regional scale of expansion (north Atlantic Ocean and the Mediterranean Sea) of this invasive species appear to be among the most dramatic ever recorded. The possible outcome of this introduction in the Atlantic is discussed.     

Morphological variation of introduced species: The case of American mink (Neovison vison) in Spain

We studied the morphology of American mink Neovison vison in five out of the six introduced populations in Spain. The spatial and temporal variation of body weight (BW), body length (BL), tail length, hind-foot length and ear length were analysed. Temporal trends in BW and BL in relation to years since mink introduction were also analyzed. In addition, we tested the effect of sex, age (juvenile, subadult and adult) and age–sex interaction, on each parameter. Morphological parameters differed between populations, illustrating the high variability of body size of American mink in different environments, and the phenotypic plasticity of the species. Annual variations were synchronized between populations, suggesting a large-scale effect on all of them. BW and BL showed a decreasing trend in both males and females in relation to years since introduction. This decrease may be related to mink's diet. Differences in sex and age were found, pointing to sexual dimorphism in adults, subadults and juveniles. The dimorphism in non-adult individuals suggests that subadult males may have a competitive advantage from subadult females in feeding and/or hunting on bigger prey from an early age (resource partitioning hypothesis).     

Immunocytological analysis of meiotic recombination in the American mink (Mustela vison)

Using immunolocalization of MLH1, a mismatch repair protein that marks crossover sites along synaptonemal complexes, we estimated the total length of the genetic map, the recombination rate and crossover distribution in the American mink ( Mustela vison ). We prepared spreads from 130 spermatocytes of five male minks and mapped 3320 MLH1 foci along 1820 bivalents. The total recombination length of the male mink genome, based on the mean number of MLH1 foci for all chromosomes, was 1327 cM. The overall recombination rate was estimated to be 0.48 cM/Mb. In all bivalents, we observed prominent peaks of MLH1 foci near the distal ends and a paucity of them near the centromeres. This indicates that genes located at proximal regions of the chromosomes should display much tighter genetic linkage than physically equidistant markers located near the telomeres.     

Importance of a traditional irrigation system in amphibian conservation in the Cinque Terre National Park (NW Italy)

In Mediterranean agricultural landscapes the impact of irrigation on biodiversity, and in particular on wildlife, remains controversial. This study investigated the role of traditional irrigation in the conservation of amphibians in the smallest and most densely populated national park in Italy, the Cinque Terre National Park (CTNP). The coastline in this area is so steep that dry stone walls were built to create arable land surfaces, irrigated by water stored in small open tanks. An almost complete census of these tanks and a survey of amphibian populations in natural and artificial habitats were undertaken from 2009 to 2012. A total of 58 water tanks were censused, 12 of them being empty, damaged or abandoned. All the tanks containing water were built in concrete and had small volume capacities (mean = 3.6, range 0.3–12.4 m³) but, overall, hosted all the seven aquatic amphibian species still present in the Park's natural freshwater habitats. Amphibians bred in 66% of the tanks still used for irrigation; large tanks were occupied more often than small tanks and hosted a different, more species-rich amphibian community. These results have management implications and confirm that, in the CTNP, extensive agriculture and biodiversity are compatible, and that maintaining traditional irrigation systems will benefit amphibian populations, especially in the case of drier climate scenarios.     

Toxin and molecular analysis of Gymnodinium catenatum (Dinophyceae) strains from Galicia (NW Spain) and Andalucia (S Spain)

Nineteen strains of Gymnodinium catenatum were isolated fromone bloom in Andalucía (S Spain) and from different bloomsin Galicia (NW Spain). The PSP toxin profiles of 16 of the strainswere analyzed, and although the saxitoxin was exclusive to theGalician strains, the corresponding dendogram showed no clusteringof the isolates from this location. However, nine out of elevenAndalusian strains were included in the same cluster. In orderto compare toxin with molecular analysis, a fragment of thelarge subunit ribosomal (LSU) RNA gene was partially sequencedfor all of the strains and fully sequenced for the five strainsthat had shown most different growth curves. Since all the strainswere identical in the LSU sequenced region, another fragmentcomprising the internal transcribed spacer 1 (ITS 1), 5.8S rRNAgene and ITS 2, was sequenced and compared among all the strains.Although this region has been used before for the detectionof intraspecific variability, it was similar in all our strains.Finally, to detect molecular differences in the strains, a randomamplified polymorphic DNA (RAPD) analysis was performed. Thecorresponding cluster analysis grouped the strains in threeclusters: one of them comprised all the Galician strains plusthree from Andalucía, another one included eight Andalusianstrains, and the last one, more separated from the two previous,was constituted by two Andalucía isolates. Although theresults of the toxin and RAPD analysis were different, sevenAndalusian strains were clustered together in both dendograms.Since neither the toxin nor the RAPD analysis brought out aclear geographic signal, we can conclude that differences intoxin content and RAPD profile between the isolates of G. catenatumare probably not linked to the location in which the strainswere collected.     

Assessment of anthropogenic pressures on South European Atlantic bogs (NW Spain) based on hydrochemical data

Cyanobacterial exudates are known to allelopathically inhibit submerged macrophytes, but the influence of the cyanobacteria growth phase on this effect is yet unknown. We compared the effect of exudates of the exponential growth phase of Microcystis aeruginosa Kütz. Elenk with exudates during the decline phase on seedlings of the macrophyte species Potamogeton crispus L. Biomass, chlorophyll content, the ratio of variable–maximum fluorescence (F _v/F _m), and light response capacity of P. crispus seedings were significantly inhibited when affected by M. aeruginosa exudates of the exponential growth phase but promoted by exudates of the decline phase. Tiller numbers of P. crispus increased by 350% under the influence of exponential phase exudates, but decreased by 60% when decline phase exudates were applied. Both exudates increased the malondialdehyde contents and decreased the activity of superoxide dismutase and peroxidase in P. crispus seedlings. We conclude that the exponential growth phase of cyanobacteria rather than the decline phase is important for disrupting photosynthesis and for inducing oxidative stress in submerged macrophytes. Planting P. crispus should thus not be applied in summer but during the cyanobacteria decline phase.     

The impact of the American mink (Neovison vison) on native vertebrates in mountainous streams in Central Spain

The American mink (Neovison vison) is responsible for the widespread decline of its prey species in the regions where it is an invasive species. The current expansion of the mink in the Iberian Peninsula has aroused concern among conservationists about its negative impact on the rich native fauna. However, evidence for this is still scarce, although there are several studies establishing a direct causal relationship between declining native species and the presence of the American mink. Thus, it is important to further investigate the responses of native species to the American mink in several habitats and locations to enhance our knowledge about the patterns of the effect of the mink in Spain, as well as to inform conservation actions. A field study of the impact of the American mink on a mountainous vertebrate community in central Spain is presented. We studied six species: two fish, one amphibian, one bird, and two mammals. The general results showed a species-specific sensitivity to mink presence, with the Mediterranean water shrew (Neomys anomalus) and the southern water vole (Arvicola sapidus) being the most affected because their ranges were significantly decreased after the introduction of the mink. Regarding the other species, neither their abundance nor range was apparently affected by the American mink. The predatory behavior of the mink and interactions with other carnivores could account for these results. These data aid in shedding light about the current impact of the mink on invaded areas of the Iberian Peninsula and highlight the variability of its effects, as well as the urgent need to establish a general program of control of the mink to avoid negative effects upon native prey communities. Furthermore, given the different responses of native species, we propose that measures to protect native species should be based on species-specific goals and attributes.     

Islands on the plains: metapopulation dynamics and female biased dispersal in hyraxes (Hyracoidea) in the Serengeti National Park

Two species of hyrax, Heterohyrax brucei and Procavia johnstoni, inhabit rock outcrops, or kopjes, in the Serengeti National Park, Tanzania. Such distinct 'island' habitats provide an excellent model to investigate natural metapopulation dynamics with distinct small populations with extinction and colonization events, as well as migration between populations. Allele frequencies, genetic variability and genetic distances between populations were calculated based on DNA microsatellite markers. The genetic diversity in both species of hyrax, especially P. johnstoni, was surprisingly low: allelic diversity ranged from 2 to 7 alleles per locus. This may have been induced by colonization by a small number of individuals from single source populations. F-statistics, assignment tests and calculations of pairwise relatedness all indicated female-biased dispersal in H. brucei but not P. johnstoni. Values of FIS in P. johnstoni showed an excess of homozygotes indicative of high rates of inbreeding; evidence for inbreeding could not be detected in H. brucei. Although female dispersal patterns in H. brucei seem to prevent inbreeding and consequently reduce risk of local extinction, this seems not to be the case in P. johnstoni.     

Effects of ungulates on epigeal arthropods in Sierra Nevada National Park (southeast Spain)

This paper examines the effect of ungulates on epigeal arthropod communities in two common plant communities of the high mountains of the Sierra Nevada (southeast Spain). We have compared the abundance, biomass, diversity and specific composition of arthropod communities in grazed and ungrazed plots experimentally excluded from ungulates. In general, we found that arthropods were more abundant and diverse in grazed than in ungrazed plots. However, the effect of ungulates depended on the variable considered (diversity versus abundance versus biomass). Moreover, ungulates also affected species composition. This means that without affecting diversity, ungulates can still have a strong effect on arthropod communities by changing species composition. Also, the relationship between ungulates and arthropods differed depending on the year of study and the sampling period. In conclusion, our study indicates that to extrapolate the results obtained for a group of insects, a habitat or a sampling period is not appropriate for the conservation of arthropod communities.     

Invasion of the North American Atlantic Coast by a Large Predatory Asian Mollusc

The large Asian gastropod mollusc Rapana venosa Valenciennes 1846 (Neogastropoda, formerly Muricidae, currently Thaididae) is reported for eastern North America in the lower Chesapeake Bay and James River, Virginia, USA. This record represents a transoceanic range expansion for this carnivorous species. This species has previously been introduced to the Black Sea, Adriatic Sea, and Aegean Sea. Ballast water transport of larval stages from the eastern Mediterranean or Black Sea is the suspected vector of introduction into the Chesapeake Bay; 650 adult specimens in the size range 68–165mm shell length (SL) have been collected from hard sand bottom in depths ranging from 5 to 20m at salinities of 18–28ppt. The absence of small individuals from local collections is probably related to bias in collection methods. Age of the specimens could not be determined. R. venosa is probably capable of reproducing in the Chesapeake Bay. Egg cases of R. venosa were collected from Hampton Roads, a section of the James River, in August 1998, and hatched over a 21-day period under laboratory conditions to release viable bilobed veliger larvae. Four lobed larvae developed 4 days post-hatching and apparent morphological metamorphic competency was observed 14–17 days post-hatching. Despite the provision of live substrates and/or metamorphic inducers no metamorphosis to a crawling form was observed for larvae cultured on the monospecific diet. In work performed during 1999 settlement was observed for larvae cultured on a diet of mixed flagellates and diatoms and subsequently exposed to local epifaunal species. Salinity tolerance tests were performed on larvae at 1–6 days post-hatching. No deleterious effects were observed at salinities as low as 10ppt with limited survival to 7ppt at 6 days post-hatch. Current distribution is considered in context with larval salinity tolerance tests and literature describing native Asian and introduced populations to assess potential for establishment and further range extension both within the Chesapeake Bay and along the Atlantic coast of North America. Establishment within the Bay mainstem to the Rappahannock River with minor incursions into the mouths of the southerly subestuaries is considered feasible. A projected breeding range on the Atlantic seaboard extending from Cape Cod to Cape Hatteras is considered as tenable. Potential impact of R. venosa on commercially valuable shellfish stocks throughout the projected range is cause for serious concern. Boring by the polychaete Polydora websteri is more prevalent in the younger whorls of the shell, and absent in shell laid down later in life. This pattern suggests that juvenile animals may prefer hard substrates and not adopt an infaunal lifestyle until a size in excess of 50mmSL, or after reaching maturity.     

Inbreeding affects fecundity of American mink (Neovison vison) in Danish farm mink

Inbreeding is an increasing problem in farmed mink, because of limited exchange of individuals between farms. In this study, genetic relatedness within seven American mink (Neovison vison) colour strains originating from 13 different mink farms in Denmark was analysed using 21 polymorphic microsatellite loci. We detected large differences in the level of relatedness (range 0.017-0.520) within colour strains. Moreover, a very strong and highly significant negative correlation between the level of relatedness and fecundity was observed (r = 0.536, P < 0.001) [Correction added after online publication on 9 March 2011: r(2) has been changed to r]. To our knowledge, this is the first time that such a correlation has been demonstrated for commercially farmed mink.     

Seasonal variations of pollution indicators in a wildfowl reserve (Do∼nana National Park, Spain)

Pollution indicators in Do∼nana National Park show a cyclic seasonal pattern with maximum level in the autumn and minimum in the spring. While faecal streptococci proved to be the best indicator micro-organisms in this type of salty, alkaline environment, total coliforms gave an overestimation of pollution because of the presence of hydroteluric coliforms.     

Distribution of taxa with alkaloids and/or related compounds in Vikos-Aoos National Park (NW Greece)

A screening of alkaloids was applied to 116 angiospermae taxa (species and subspecies) of Vikos-Aoos National Park (NW Greece). Positive results were obtained from 48 taxa. A higher frequency of alkaloids and/or related compounds was recorded in the widespread taxa than those having a narrower range. Furthermore, a distribution pattern of the incidence of alkaloids in the different vegetation zones of the National Park was detected; the highest number of both short-lived and perennial alkaloid-bearing taxa was found in the ruderal sites. Our results are compatible with some earlier works showing that the occurrence of nitrogen-containing secondary metabolites is related to habitat conditions.     

HLA gene and haplotype frequencies in galicia (NW Spain)

The genetic structure of six populations of Iran (Turks, Kurds, Lurs, Zabolis, Baluchis and Zoroastrians) was examined using data on blood groups, serum proteins and cell enzymes. Our results show conclusively that there are genetic differences among the six populations and the analysis of superimposed R and S matrices defined by Harpending & Jenkins (1973) show that the dispersion of some of the alleles correspond to the dispersion of the populations. The F_ST estimates are not large enough to favour selection on any of the loci studied. The F_IT and F_IS estimates are positive and moderately high suggesting that the genetic differentiation to some extent is influenced by inbreeding.     

Distribution of Castanea pollen in Galician honeys (NW Spain)

With the aim to know the importance of theCastanea pollen in the Galician honey(N. W. Spain), the interannual oscillations withinthe areas of production and the most activephenological period for bees, we have madethe melissopalynological analysis of: 599samples of honey collected during the period1990–1999 in Galicia, the production of 40beehives during three consecutive years(1990, 1991, 1992), the partial production during1990 of two beehives situated at distant pointsin our geography.     

Diversity measurements in shrubland communities of Galicia (NW Spain)

Diversity was studied in 10 communities, including the understory of native oak woodland, planted woodlands (pine and eucalypt), and shrublands in the strict sense (heathlands, broom shrublands, gorse shrublands).In each community, species richness, diversity, dominance and evenness were analysed. Differences were observed among communities with regard to species composition, richness in annual herbs, perennial herbs and shrubs, dominant plant families (Ericaceae, Papilionaceae) and diversification of shrub species.The possible relations between environmental stress and/or human influences on differences in diversity are discussed.     

Vegetational change in the Balearic Islands (Spain) during the Holocene

New information about the vegetational history of the Balearic Islands during part of the Holocene derives from the results of a pollen study of a 20‐metre‐deep core from Cala Galdana on the SW coast of Minorca.

The lower part of the pollen diagram at the beginning of the Atlantic Period records significant quantities of pollen of Corylus and also local taxa indicating swamp vegetation. In the middle part, Corylus is greatly reduced, AP percentages decrease appreciably and Olea and Ericaceae reach important values, while Plantago Poaceae and Cerealia increase significantly. In the upper part, a rise in Chenopodiaceae occurs, during which a slight increase of the arboreal taxa takes place with greater dryness. Most recently, vegetation changes reflect human activity.     

Trade-offs in plankton species richness arising from drought: insights from long-term data of a National Park wetland (central Spain)

Wetlands are considered vulnerable ecosystems of both high species richness and socio-economic value. In semi-arid regions, these ecosystems often experience long drought periods that are usually aggravated by local water overexploitation. Drought leads to: (i) reduced flooding area, (ii) isolation of water bodies, (iii) increased areas of dry sediments and shoreline length, and (iv) increased ionic concentration. These processes affect aquatic populations in a species-specific way and can have antagonistic effects on taxon richness. Here, we highlight long-term (1997–2008) trade-off effects on plankton species richness linked to drought in a semi-arid wetland (Las Tablas de Daimiel National Park, central Spain). Annual average phytoplankton species richness increased from wet- (1997–1998) to dry years (2001–2002) and taxon richness diminished again when drought was more severe (2007–2008). Zooplankton changes were more complex depending on taxonomic groups and the body size of the organisms, total species loss being related to hydrological conditions. Half of the algal species recorded in 2007–2008 and one-tenth of total zooplankton taxa were new comers in the wetland, because salinization, eutrophication and submerged macrophytes occurring in different sites enhanced species turnover and mitigated homogenization of beta diversity. Maintenance of one water body with a constant water level and macrophytes was the key to preventing the collapse of plankton richness. Our study has demonstrated that plankton can be very useful for tracking environmental changes of wetlands, thus giving the environmental manager another tool to enhance the conservation of wetlands and their biota.     

Distribution of live benthic foraminifera in the Ría de Vigo (NW Spain)

The spatial and vertical distributions of live benthic foraminifera from the muddy central axis of the Ría de Vigo were examined under downwelling and upwelling conditions. The spatial distribution of the main benthic foraminiferal species is controlled by salinity variations (San Simón Assemblage), food availability (Outer Ría Assemblage) and oxygen concentrations and/or reducing microenvironmental conditions in the sediment (Inner Ría Assemblage).The microhabitat distribution of benthic foraminifera is mainly dependant on the oxygenation/redox conditions in the sediment and the vertical segregation of food. In the inner areas of the ría, low oxygen and/or reducing microenvironmental conditions prevent the vertical segregation of microhabitats. In outer areas oxygen penetration is deep but microhabitat partitioning only occurs in the presence of additional food resources (mainly fresh organic carbon from phytoplankton blooms) which triggers the colonisation of the surface layer by new species and the migration upwards and reproduction of opportunistic species.