Etude des bactéries associées aux Algues marines en culture

Some bacteria strains have been isolated from marine algae cultures and assigned tentative genera and species. Observations and tests were conducted using Bergey's manual and specific papers on marine bacteria as taxonomic keys. The genera Pseudomonas, Flavobacterium and Achromobacter appear to be the most important, as far as the number of species is concerned.     

Social learning drives handedness in nectar-robbing bumblebees

Bumblebees have been found to observe and copy the behaviour of others with regard to floral choices, particularly when investigating novel flower types. They can also learn to make nectar-robbing holes in flowers as a result of encountering them. Here, we investigate handedness in nectar-robbing bumblebees feeding on Rhinanthus minor, a flower that can be robbed from either the right-hand side or the left-hand side. We studied numerous patches of R. minor spread across an alpine landscape; each patch tended to be robbed on either the right or the left. The intensity of side bias increased through the season and was strongest in the most heavily robbed patches. We suggest that bees within patches learn robbing strategies (including handedness) from one another, either by direct observation or from experience with the location of holes, leading to rapid frequency-dependent selection for a common strategy. Primary robbing was predominantly carried out not only by a specialist robbing species, Bombus wurflenii, but also by Bombus lucorum, a widespread generalist. Both species adopted the same handedness within particular flower patches, providing the first evidence for social learning crossing the species boundary in wild insects.     

Reproduction and development of Sabella media,a sabellid polychaete with extratubular brooding

Known reproductive patterns in the polychaete family Sabellidae include: (1) broadcasting of gametes, (2) depositing of benthic egg masses, (3) brooding outside the lip of the tube, and (4) brooding within the tube. There is little information for sabellids in the third category; there-fore we have studied the reproductive biology of Sabella (=Demonax) media (Bush), one of the few species known to brood its early developmental stages outside the tube. A total of 32 adults of S. media with egg cocoons were collected from the surfaces of compound ascidians (Aplidium sp. and Didemnum sp.) and from holdfasts of a brown alga (Hedophyllum sessile) at Eagle Cove, San Juan Island, Washington, USA, from June 1981 through June 1982, between tidal levels of 0.0 and 0.6 m. The donutshaped cocoons, each containing over 1 000 eggs, are deposited just outside the tube aperture from April through September. Larval development takes place within the cocoon through the 3-setiger stage, at which time the larvae emerge (about 8 d after egg deposition). The newly hatched larvae are demersal and swim near the bottom of the culture dish for 1 d before settlement. Metamorphosis takes nearly a week, and initial formation of the tube is also gradual. The reproductive patterns within the family Sabellidae are discussed, and the adaptive significance of extratubular brooding considered.     

A note on option value and the expected value of consumer's surplus

In roughly contemporaneous papers, Cicchetti and Freeman (Quart. J. Econ., 1971) and Schmalensee (Amer. Econ. Rev., 1972) reached apparently conflicting conclusions about the sign taken by option value. Cicchetti and Freeman conclude that option value is always non-negative. Schmalensee concludes that option value may be either positive or negative, depending upon the circumstances. This paper reconciles these seemingly contradictory conclusions. It is demonstrated that Cicchetti and Freeman's unambiguous conclusions concerning the sign of option value are the result of two special strong assumptions not imposed by Schmalensee.     

Distribution and seasonal abundance of Polygordius spp. (Class: Polychaeta; Family: Polygordiidae) exo- and endolarvae in the southern Mid-Atlantic Bight,USA

The importance life history plays in understanding population dynamics and the functional roles of species for predicting climate change scenarios are well established. Yet, in the marine environment, the complete life history is unknown for many species, especially the link between morphologically and ecologically distinct planktonic larvae, and their corresponding benthic adult forms. Integration of meroplankton abundance, benthic adult species, larval morphology, and molecular data was employed to unravel the complete life history of Polygordius, a dominant polychaete in sandy shelf sediments of the Mid-Atlantic Bight. Polygordius species are unusual, having two distinct planktonic larval forms: an exolarva and an endolarva. Extensive sampling in the southern Mid-Atlantic Bight with careful preservation of meroplankton (2006–2007) revealed the identity of multiple stages of exo- and endolarvae, and their spatial, seasonal, and vertical distribution. Molecular and morphological evidence indicated exolarvae are Polygordius jouinae and endolarva are an undescribed species. Structure and development of these larvae differed greatly. P. jouinae exolarvae were found off Delaware Bay to North Carolina. At some stations, they were abundant, with densities up to 4,013 m^?3, comprising >90 % of the total meroplankton. Exolarvae spent up to a month in the plankton starting in March/May depending on year, settlement began in July when larvae were at least 2 mm in length, and by October were no longer observed in the plankton. These findings are consistent with the distribution patterns and life cycle known for adults. This is the first report of endolarvae north of Cape Hatteras.     

The state of Darwinian theory

The year 2009 marked both the bicentenary of Charles Darwin’s birth, and the passage of 150 years since the publication of his revolutionary book, commonly referred to as The Origin of Species (Darwin 1859). As part of the national celebrations that took place in the UK, a meeting on ‘Mathematical Models in Ecology and Evolution’ was held in Bristol on September 10 and 11, with a special focus on the mathematical modelling and application of Darwin’s key theories. This special issue collects together selected papers presented at the meeting, including contributions by the four invited keynote speakers, Rob Boyd, A. W. F. Edwards, Hanna Kokko and Franjo Weissing, as well as papers received after the event. The topics of these papers span the modelling of a very wide range of Darwin’s ideas, particularly evolution through natural selection, the origin of species, sexual selection, altruism and cooperation, and pangenesis, as well as applications of Darwinian thinking to the behaviour of animals, humans, and even human societies. It is hoped that this collection of papers will provide a useful snapshot of the state-of-the-art in Darwinian theory after the last one and a half centuries, and help to identify potential directions for research over the next.     

Assessment of the aquatic biodiversity of a threatened coastal lagoon at Bimini, Bahamas

Coastal biodiversity is threatened worldwide by both direct and indirect anthropogenic activities. To more effectively manage and protect coastal biodiversity, accurate assessments of genetic, species, and ecosystem level diversity are required. We present the results from an assessment of the aquatic species diversity of a small (3?km²), shallow, mangrove-fringed Bahamian lagoon (the North Sound) subject to ongoing anthropogenic development. The assessment was conducted through a collation of field observations and data in published literature. We found that eight angiosperm species, 30 macroalgal species, and 370 animal species (including 95 fishes, 69 arthropods, 56 birds, and 45 mollusks) were documented within the lagoon. At least 11 of these species are of conservation concern, such as the critically endangered smalltooth sawfish (Pristis pectinata) and hawksbill turtle (Eretmochelys imbricata). Comparisons of community similarity indicated that the North Sound has a relatively distinct fauna and flora, but available data suggest that the species found there are most similar to those found in nearby habitats in Cuba. The lagoon forms a key nursery habitat for many species, including lemon sharks (Negaprion brevirostris), Caribbean spiny lobsters (Panulirus argus), and queen conch (Strombas gigas). Recently, the lagoon was included as part of a new marine protected area (MPA), but much of the habitat has already experienced considerable anthropogenic disturbance and the MPA boundaries have yet to be established. We have therefore analyzed the lagoon biodiversity and expect the data presented here to serve as a baseline for future comparisons.     

Introduction to the special issue of Ecological Modelling: “Advances in Modeling Estuarine and Coastal Ecosystems: Approaches, Validation, and Applications”

The development and application of ecosystem models in estuarine and coastal systems has grown exponentially over the past four decades. Models have become ensconced as major tools for both heuristic study of ecosystem structure and function as well as for informing management decisions, particularly with respect to cultural eutrophication. In recent years an ever-expanding toolbox of modeling approaches is being offered to complement traditional methods. This expansion of modeling in estuarine and coastal science was exemplified by four sessions devoted to modeling at the 2007 biennial conference of the Estuarine Research Federation in Providence, RI. We felt the time was right to propose a special session of Ecological Modelling to synthesize talks from these sessions to present the state of the art in coastal and estuarine modeling. The collection of papers contained in this special issue presents a diversity of traditional and novel modeling approaches, methods for assessing model validity and predictability, and the utility of models in management applications. We believe that together these papers provide an excellent overview of current approaches to modeling estuarine hydrodynamics, water quality, and ecosystem/food web dynamics, applications of complex and relatively simple modeling approaches, applications in both deep and shallow coastal systems, goals relevant for both heuristic and management applications, and perspectives based on traditional mechanistic model development as well as more recent alternative approaches.     

Attachment strength and colonization patterns of two macrofouling species on substrata with different surface tension (in situ studies)

Attachment strength and colonization patterns of one barnacle (Balanus c.f. variegatus) and one polychaete species (Pomatoleios kraussii) on seven artificial substrata with surface tensions between 19 and 64.5 mNm^-1 were studied between June 1991 and January 1992 at Laem Than (Chonburi province, Gulf of Thailand). The purpose of the present study was to demonstrate the role that surface tension plays under natural conditions in colonization success by these species. Does stronger adhesion to one substratum result in higher densities of specimens on that particular surface? Although both species adhere much better on substrata with higher surface tension than on surfaces with low surface tension (B. c.f. variegatus: between 0.04×10⁵ and 16.35×10⁵ Nm^-2 on surfaces of 22 and 33.5 mNm^-1, respectively; P. kraussii: between 0.22×10⁵ and 1.73×10⁵ Nm^-2 on 19 and 33.5 mNm^-1, respectively), colonization pattern is not influenced by surface tension. The major factors influencing settlement patterns seem to be space competition for B. c.f. variegatus and attraction to already settled adults by P. kraussii. The results show that the importance of surface tension in marine fouling control is limited because organisms colonize substrata successfully despite lower adhesion. Attachment strength is not a limiting factor under natural conditions.     

Cell-cell recognition system in gorgonians: description of the basic mechanism

A comparative investigation of the chemical composition of Thalassiosira antarctica var. antarctica vegetative and resting stages revealed C:N and C:chl a ratios to be lower in vegetative cells. These trends primarily reflect vegetative levels of C/cell below, and N/cell and chl a/cell levels above those of spores. There was a change in chemical composition with the initial formation of resting spores, and spores continued to modify their composition while maintained in a cyclic light/dark regime for about one and one half weeks. Most notable was a net increase in carbon and chlorophyll a per cell. Spores then subjected to darkness for over one week appeared to retain most of the carbon and chlorophyll a previously synthesized. These findings support the idea that resting spores enhance the survival capabilities of a species under adverse conditions.     

A general bioeconomic simulation model for annual-crop marine fisheries

A generalized bioeconomic simulation model of annual-crop marine fisheries is described and its use in marine fisheries management is demonstrated. The biological submodel represents the recruitment of new organisms into the fishery, the movement of organisms from one fishing area to another and from one depth to another, the growth of organisms and the mortality of organisms resulting both from natural causes and from fishing. The economic submodel represents the fishing effort exerted on each resource species, the monetary costs of fishing, the value of the harvest and the rent (or excess profits) to the fishery.Basic dynamics of the model results from changes in the number of organisms in the fishery over time, which can be summarized as a set of difference equations of the general form ΔN/Δt = R + I ? E ? M ? F where ΔN/Δt is the net change in number of organisms in the fishery over time, R is recruitment, I is immigration, E is emigration, M is natural mortality and F is fishing mortality. R is a driving variable, whereas I, E, M and F are functions of the state of the system at any given point in time. The model can be run in a deterministic or stochastic mode. Values for parameters affecting rates of recruitment, movement, growth, natural mortality and fishing mortality can be selected from uniform, triangular or normal distributions.Use of the model within a fisheries-management framework is demonstrated by evaluating several management alternatives for the pink shrimp (Penaeus duorarum) fishery on the Tortugas grounds in the Gulf of Mexico. Steps involved in use of the model, including parameterization, validation, sensitivity analysis and stochastic simulations of management policies, are explained.     

Practical sustainability criteria for decision-making

SUMMARY

The new paradigm of sustainability necessitates revisions to traditional decision-making processes. This paper, which is the first in a series of four, outlines the changes required for decision-making to reflect sustainability concerns. Three sustainability criteria, that are the focus of the three subsequent papers, are introduced and the rationale for each is explained. A framework for incorporating the three sustainability criteria into the decision-making process is briefly outlined. The paper ends with the introduction to a case study, the North Central Project (NCP) for electricity supply alternatives. The NCP is used in the three following papers to demonstrate the individual components of the new approach to sustainable decision-making.     

Patterns of Citations of Open Access and Non‐Open Access Conservation Biology Journal Papers and Book Chapters

Abstract: Open access (OA) publishing, whereby authors, their institutions, or their granting bodies pay or provide a repository through which peer‐reviewed work is available online for free, is championed as a model to increase the number of citations per paper and disseminate results widely, especially to researchers in developing countries. We compared the number of citations of OA and non‐OA papers in six journals and four books published since 2000 to test whether OA increases number of citations overall and increases citations made by authors in developing countries. After controlling for type of paper (e.g., review or research paper), length of paper, authors’ citation profiles, number of authors per paper, and whether the author or the publisher released the paper in OA, OA had no statistically significant influence on the overall number of citations per journal paper. Journal papers were cited more frequently if the authors had published highly cited papers previously, were members of large teams of authors, or published relatively long papers, but papers were not cited more frequently if they were published in an OA source. Nevertheless, author‐archived OA book chapters accrued up to eight times more citations than chapters in the same book that were not available through OA, perhaps because there is no online abstracting service for book chapters. There was also little evidence that journal papers or book chapters published in OA received more citations from authors in developing countries relative to those journal papers or book chapters not published in OA. For scholarly publications in conservation biology, only book chapters had an OA citation advantage, and OA did not increase the number of citations papers or chapters received from authors in developing countries.     

Geographic variation in allele frequency of the gamete recognition protein M7 lysin throughout a mosaic blue mussel hybrid zone

Divergence at gamete recognition loci is hypothesized to result in speciation in broadcast spawning invertebrates. Many gamete recognition loci evolve quickly and show patterns of positive selection, yet the advantage of divergence is rarely known. M7 lysin is a sperm protein in the Mytilus edulis species complex that shows evidence of adaptive evolution. This locus is polymorphic with two distinct clades within Mytilus galloprovincialis, one of which, the D clade, shows the strongest signal of positive selection. We tested whether the geographic patterns in allele frequency were consistent with the hypothesis that positive selection on D clade alleles (G _D ) was due to reinforcement. Populations of M. edulis showed little evidence of introgression of G _D alleles, but there was no consistent evidence of reproductive character displacement. The lack of consistent patterns expected of reinforcement suggests that another mechanism is likely responsible for the adaptive divergence of M7 lysin.     

Reproductive success of parasitized males in a marine reef fish

Parasitism is hypothesized to reduce reproductive success in heavily parasitized males because females may preferentially mate with less parasitized males (parasite-mediated sexual selection) or parasites may compromise male competitiveness. In marine systems, this hypothesis is largely unexplored. This paper provides the first confirmed record of a copepod ectoparasite (Caligus buechlerae Hewitt 1964) on the common triplefin (Forsterygion lapillum) and evaluates the hypothesis that males parasitized with C. buechlerae experience lower reproductive success than unparasitized males (as determined by the presence and area of eggs within male nests). We found that 38 % of males we surveyed were infected with at least one C. buechlerae, with a median of two individuals per infected male. About 32 % of males were defending eggs, with 62.5 % of those males infected with at least one parasite. Males of greater total length (TL) were both more likely to be infected and more likely to be defending eggs. However, when statistically accounting for the effects of TL, parasite infection had no effect on the probability of defending eggs, or the average surface area of eggs when present. Positive covariation in fish length, the presence of eggs and parasite infection observed here potentially suggest that the importance of parasitic infection on reproductive success may depend upon the strength of selection for larger male body size. Our study is one of the few studies to investigate the effects of ectoparasites on reproductive success in reef fish and also provides a quantitative measure of infection for a widespread species within New Zealand.     

Calanus marshallae,a new species of calanoid copepod closely allied to the sibling species C. finmarchicus and C. glacialis

Species of the copepod genus Calanus frequently dominate the marine zooplankton in boreal and arctic waters. Up to now there have been no operational means of identifying several species closely related to Calanus finmarchicus. Reanalysis of these taxa, using material from plankton samples collected throughout Northern Hemisphere polar and coreal waters, shows that there are 3 sibling species which have been previously combined under the names C. finmarchicus and C. glacialis. Several new taxonomic characters permit unequivocal identification of C. finmarchicus, C. glacialis, and a new species, C. marshallae. Claims that C. finmarchicus and C. glacialis are subspecies are refuted; there is no evidence that the two species continuously intergrade either where they co-occur or where they are allopatric, nor is there evidence that the two species hybridize. C. finmarchicus is basically restricted to the North Atlantic Ocean and C. marshallae to the North Pacific Ocean and Bering Sea; C. glacialis is primarily an Arctic species, but its geographical distribution slightly overlaps those of the other two species. Taxa closely related to C. finmarchicus and C. helgolandicus probably represent two separate, but closely linked evolutionary lineage; species of these two lineages are placed in one of two species groups, the finmarchicus group and the helgolandicus group.     

Studies on the reproductive cycles of Cardium edule and C. glaucum

Two allopatric populations of Cardium edule and two of C. glaucum were sampled over a period of 16 months and their gonad maturity cycles compared by histological methods. The onset of both spermatogenesis and oogenesis in C. edule took place between September and October; in C. glaucum it was slightly later, between October and November. Development of the gonads continued slowly throughout the winter, C. glaucum developing marginally faster than C. edule. Maturation accelerated in April and May, with the gonads of both species becoming fully ripe in late May and early June. Spawning of the two species approximately coincided at all the localities investigated. Spawning in C. edule was better coordinated than in C. glaucum. Transplanting cockles of one species to the typical habitat of the other did not appreciably alter the spawning period. The separation of spawning periods in sympatric associations of the two cockles is discussed.