Use of Sediment Bioassays to Verify Efficacy of Caulerpa taxifolia Eradication Treatments

Infestations of the marine macrophytic alga Caulerpa taxifolia were discovered in Agua Hedionda Lagoon, California in 2000. Rapid response actions included containment under pvc tarps coupled with injection of liquid sodium hypochlorite. To assess the efficacy of these treatments, replicated sediment cores were removed from representative treated sites and transferred to grow-out facilities. Similar cores from uninfested (control) sediments were removed, inoculated with viable explants of C. taxifolia and placed in grow-out facilities. Results from two sampling periods (1 year, 2 years post-treatment) showed that no viable C. taxifolia emerged in cores, and that inoculated “control” sediments supported normal growth. Eelgrass ( Zostera marina L.) seedlings emerged from native seed-banks in “treated” cores, which also supported growth of some invertebrates (annelid worms and hydroids). This study provided essential verification of C. taxifolia eradication efforts, and demonstrates the feasibility of incorporating quality control/quality assurance components in rapid response actions. Results of this study also suggest that seeds of eelgrass are viable for at least two years. (PDF has 9 pages.)

Further expansion of the alien seaweed Caulerpa taxifolia var. distichophylla (Sonder) Verlaque, Huisman & Procacini (Ulvophyceae, Bryopsidales) in the Eastern Mediterranean Sea

Date of Acceptance: 27/04/2015 We are grateful to Andreas Antoniou (Dep. of Environment, Ministry of Agriculture, Rural Development & Environment, Cyprus) for his assistance in the preparation of the illustrations. We would also like to thank Dr. Sotiris Orfanidis (NAGREF – Fisheries Research Institute, Kavala, Greece) for his valuable advice and both the DFMR and HSR / HCMR Rhodes crew and George Hatiris for their help in samplings. Special thanks are due to Dinos Leonidou (SeaQuest Divers Cyprus) for accompanying the deep dive for sampling Caulerpa at Cavo Greco. We are grateful to the Total Foundation (Paris) for its funding support to this study within the framework of the project “Brown algal ecology and biodiversity in the eastern Mediterranean Sea” and to the MASTS pooling initiative (Marine Alliance for Science and Technology for Scotland, funded by the Scottish Funding Council and contributing institutions; grant reference HR09011).

Invasionsoft: a web-enabled tool for invasive species colonization predictions

Predicting and averting the spread of invasive species is a core focus of resource managers in all ecosystems. Patterns of invasion are difficult to forecast, compounded by a lack of user-friendly species distribution model (SDM) tools to help managers focus control efforts. This paper presents a web-based cellular automata hybrid modeling tool developed to study the invasion pattern of lionfish (Pterois volitans/miles) in the western Atlantic and is a natural extension our previous lionfish study. Our goal is to make publically available this hybrid SDM tool and demonstrate both a test case (P. volitans/miles) and a use case (Caulerpa taxifolia). The software derived from the model, titled Invasionsoft, is unique in its ability to examine multiple default or user-defined parameters, their relation to invasion patterns, and is presented in a rich web browser-based GUI with integrated results viewer. The beta version is not species-specific and includes a default parameter set that is tailored to the marine habitat. Invasionsoft is provided as copyright protected freeware at http://www.invasionsoft.com.

Acyclic diterpene alcohols isolated from four algae of Bryopsidophyceae and their toxicity

Three new acylic diterpenoids belonging to the class of phytol series have been isolated. They were obtained from the ethyl acetate soluble fractions of four siphonaceous green seaweeds, Bryopsis pennata Lamour., Caulerpa taxifolia (Vahl) C. Ag., Codium decorticatum (Woodw.) Howe and Valoniopsis pachynema (Mart.) Børg., collected from Karachi coast of Pakistan. Structures of these compounds were elucidated with the help of spectroscopic methods and confirmed by comparison with the known compounds. Even the known compounds are being reported for the first time from a green algal source. All the compounds were found to display a strong toxicity at all the three concentrations tested in the brine shrimp bioassay.

Historical data reveal power-law dispersal patterns of invasive aquatic species.

Understanding how invasive species spread is of particular concern in the current era of globalisation and rapid environmental change. The occurrence of super-diffusive movements within the context of Lévy flights has been discussed with respect to particle physics, human movements, microzooplankton, disease spread in global epidemiology and animal foraging behaviour. Super-diffusive movements provide a theoretical explanation for the rapid spread of organisms and disease, but their applicability to empirical data on the historic spread of organisms has rarely been tested. This study focuses on the role of long-distance dispersal in the invasion dynamics of aquatic invasive species across three contrasting areas and spatial scales: open ocean (north-east Atlantic), enclosed sea (Mediterranean) and an island environment (Ireland). Study species included five freshwater plant species, Azolla filiculoides, Elodea canadensis, Lagarosiphon major, Elodea nuttallii and Lemna minuta; and ten species of marine algae, Asparagopsis armata, Antithamnionella elegans, Antithamnionella ternifolia, Codium fragile, Colpomenia peregrina, Caulerpa taxifolia, Dasysiphonia sp., Sargassum muticum, Undaria pinnatifida and Womersleyella setacea. A simulation model is constructed to show the validity of using historical data to reconstruct dispersal kernels. Lévy movement patterns similar to those previously observed in humans and wild animals are evident in the re-constructed dispersal pattern of invasive aquatic species. Such patterns may be widespread among invasive species and could be exacerbated by further development of trade networks, human travel and environmental change. These findings have implications for our ability to predict and manage future invasions, and improve our understanding of the potential for spread of organisms including infectious diseases, plant pests and genetically modified organisms.

Historical data reveal power-law dispersal patterns of invasive aquatic species

Understanding how invasive species spread is of particular concern in the current era of globalisation and rapid environmental change. The occurrence of super-diffusive movements within the context of Lévy flights has been discussed with respect to particle physics, human movements, microzooplankton, disease spread in global epidemiology and animal foraging behaviour. Super-diffusive movements provide a theoretical explanation for the rapid spread of organisms and disease, but their applicability to empirical data on the historic spread of organisms has rarely been tested. This study focuses on the role of long-distance dispersal in the invasion dynamics of aquatic invasive species across three contrasting areas and spatial scales: open ocean (north-east Atlantic), enclosed sea (Mediterranean) and an island environment (Ireland). Study species included five freshwater plant species, Azolla filiculoides, Elodea canadensis, Lagarosiphon major, Elodea nuttallii and Lemna minuta; and ten species of marine algae, Asparagopsis armata, Antithamnionella elegans, Antithamnionella ternifolia, Codium fragile, Colpomenia peregrina, Caulerpa taxifolia, Dasysiphonia sp., Sargassum muticum, Undaria pinnatifida and Womersleyella setacea. A simulation model is constructed to show the validity of using historical data to reconstruct dispersal kernels. Lévy movement patterns similar to those previously observed in humans and wild animals are evident in the re-constructed dispersal pattern of invasive aquatic species. Such patterns may be widespread among invasive species and could be exacerbated by further development of trade networks, human travel and environmental change. These findings have implications for our ability to predict and manage future invasions, and improve our understanding of the potential for spread of organisms including infectious diseases, plant pests and genetically modified organisms.

La pèrdua de la biodiversitat : quadern de l'alumne. 'La pérdida de la biodiversitat : cuaderno del alumno'.

Se completa con una guia para el profesor, editada con el mismo número de esta colección

La pèrdua de la biodiversitat : unitat didàctica. Guia del professor. 'La pérdida de la biodiversitat : unitat didàctica. Guía del profesor'.

Se complementa con un cuaderno para el alumno, que supone el mismo número de esta colección

Habitat alteration and community-level effects of an invasive ecosystem engineer: a case study along the coast of NSW, Australia

We investigated the effects of the habitat-modifying green algae Caulerpa taxifolia on meiobenthic communities along the coast of New South Wales, Australia. Samples were taken from unvegetated sediments, sediments underneath the native seagrass Zostera capricorni, and sediments invaded by C. taxifolia at 3 sites along the coast. Meiofaunal responses to invasion varied in type and magnitude depending on the site, ranging from a slight increase to a substantial reduction in meiofauna and nematode abundances and diversity. The multivariate structure of meiofauna communities and nematode assemblages, in particular, differed significantly in sediments invaded by C. taxifolia when compared to native habitats, but the magnitude of this dissimilarity differed between the sites. These differential responses of meiofauna to C. taxifolia were explained by different sediment redox potentials. Sediments with low redox potential showed significantly lower fauna abundances, lower numbers of meiofaunal taxa and nematode species and more distinct assemblages. The response of meiofauna to C. taxifolia also depended on spatial scale. Whereas significant loss of benthic biodiversity was observed locally at one of the sites, at the larger scale C. taxifolia promoted an overall increase in nematode species richness by favouring species that were absent from the native environments. Finally, we suggest there might be some time-lags associated with the impacts of C. taxifolia and point to the importance of considering the time since invasion when evaluating the impact of invasive species.

Comparative haemagglutinic activity in the species of Caulerpa and Ulva (Chlorophyta) of Karachi coast

Aquous extracts of 24 species of green seaweeds, 13 of Caulerpa Lamour and 11 of Ulva Linn, were collected from the coastal areas near Karachi, Pakistan and tested for haemagglutination against human erythrocytes of blood groups A,B,AB and O and compared. All the species of Caulerpa and seven of Ulva exhibited a positive activity, the former genus (a member of Bryopsidophyceae) appeared to possess more phycohaemagglutinins than the latter (a member of Ulvophyceae). The haemagglutinic activity proved to be quite helpful in the distinction of various species of both the genera.

The free and combined amino acid contents in species of Caulerpa from southeast coast of India

Caulerpa racemosa var. macrophysa, C. racemosa var cornyphora and C. scalpelliformis are analyzed by quantitative paper chromatographic technique for their amino acid contents in proteins, peptides and free state. It is found that no appreciable variation occurs in the quality of amino acid make up in these algae; but quantitative differences are apparent in them. Moreover, both qualitative and quantitative variations occur in the amino acid make up of the peptides, and in the free state. The results are compared with those of the other investigations.

Taxonomic study of coenocytic green algae commonly growing on the coast of Karachi

Twelve commonly occurring coenocytic and siphonaceous species of marine benthic algae, i.e., Bryopsis pennatta Lamouroux, Caulerpa chemnitzia (Esper) Lamouroux, Ca. faridii Nizamuddin, Ca. manorensis Nizamuddin, Ca. racemosa (Forsskal) J. Agardh, Ca. taxifolia. (Vahl) C. Agardh, Chaetomorpha antennina (Bory de Saint-Vincent) Kutzing, Cladophora uncinella Harvey, Codium decorticatum (Woodward) Howe, Co. flabellatum Nizamuddin, Co. iyengarii Borgesen, and Valoniopsis pachynema (Martens) Borgesen, belonging to four different orders of the class Bryopsidophyceae, division Chlorophyta, were collected from the intertidal region of different coastal areas near Karachi (Pakistan) and investigated taxonomically. Codium decorticatum is a new report from this region and Co. decorticatum, Co. flabellatum and Co. iyengarii are described for the first time from the coast of Pakistan.