摘要:

Abstract.Tagged individuals ofMarthasterias giacialis(L.) followedin situfor 24 h cycles or for up to 4 consecutive days show that sea‐star activity is not only nocturnal; we observed a non‐synchronized (between individuals) movement, with 1 or 2 (ocassionally 3) peaks; movement, occurs mainly between 6:00 p.m. and 9:00 a.m., without a clear peak at the population level, independent the prevailing light conditions (for 6:00–9:00p. m. and 6:00–9:00a. m. periods).M. giacialisshows periods of inactivity ranging from 1 to 3 days. It is hypothesized that the study site is visited for short term feeding raids by individuals coming from the deep water and then movi

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1987.tb00177.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract.The pyramidellid snail,Boonea (= Odostomia) impressa(SAY), is an important ectoparasite of the oyster,Crassostrea virginica(Gmelin). The small‐scale spatial distribution of snails was examined in 11 oyster populations in the Copano Bay ‐ Aransas Bay area of the Texas coast. Snails were contagiously distributed (s2/>1) and positively spatially autocorrelated. Patchiness was better developed and patches were larger on enclosed reefs than on more exposed open‐bay reefs, probably because higher wave energy and increased distance between oyster clumps limited clump‐to‐clump movement by snails on open‐bay reefs. Small snails were consistently distributed differently from large snails because small snails were less host specific. As the snails grow, a narrowing of host preference results in a substantial change in spatial distribution. Snails were consistently more contagiously distributed than their hosts; however, snail distribution was not host‐density dependent. Factors determining the spatial distribution of the host had surprisingly little effect on the distribution of snails. Snail aggregates apparently form randomly by chance meetings of a few snails and then grow by attraction of additional snails. Consequently, snail behavior, which determines the size and length of time a patch retains its integrity, and the age distribution of the snail population may be the two most important factors, besides population size, determining the impact ofB. impressaon oyste

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1987.tb00178.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract.Tagged individuals of the sea urchinParacentrotus lividusfollowed in Port Cros Island showed mostly nocturnal movements, with individual peaks of activity which were not coordinated for the population during the night period. The straight line distance travelled in 24 h has a mean value of 49 cm, with a range of 0 to 240 cm. Neither sea urchin size nor depth affect activity. The urchins living on rocky substrate moved significantly more than those on seagrass beds. From one day to another, the distance travelled by the population of urchins varies significantly; this is not related to season. The activity is negatively correlated with the mean wind speed; during a period of turbulence lasting several hours, movement was significantly oriented to the deep. Periods of inactivity of 1 or 2 days were observed; they are not coordinated for the individuals followed, and the relation between feeding and movement is not clear. Urchins seem to stay in a quite small area, at least for some months.

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1987.tb00179.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract.An investigation of the properties of particles found in wrack beds and suspended in the water body of aPosidonia oceanicasystem led to the following conclusion: except for the period of the leaf fall and at times of strong water movement (e.g.winter storms), the majority of the particles in the water show no similarity with seagrass particles. This is based on the comparison of C: N ratios and SEM inspection. Information on the magnitude of DOC fluxes in this system led to the formulation of the phase shift hypothesis from DOM to POM. Because wrack particles were shown to have relatively fast settling rates, it is expected that processes like adsorption onto inorganic particles, micellation and aggregate formation have more importance in regulating particle density in the water body than the resuspension of directly fractionatedPosidoniadebris. The implication of these findings are discussed and the importance of the Mediterranean seagrassP. oceanicaas an energy source supporting secondary production in adjacent ecosystems is questioned.

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1987.tb00180.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract.One hundred ninety‐seven macroalgal taxa, belonging to four classes, were identified at seven characteristic stations of the Saronikos Gulf.Species diversity was higher in cleaner waters. From the outer to the inner section, the number of species and the coverage increased inBryopsidophyceaeand decreased inPhaeophyceaeandRhodophycea

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1987.tb00181.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Book reviewed in this article:Newig, J.&H.Theede(Eds.): Die Ostsee. Natur und Kulturraum. Husum Druck‐ u. Verlagsgesellschaft mbH u. Co. KG, HusumHarris, G. P.: PhytopJankton ecology: structure, function and fluctuation. Chapman&Ha

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1987.tb00182.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY

摘要:

Abstract.Several species of cyanobacteria, diatoms and one euglenid alga populated the littoral zone of hypersaline solar ponds investigated over a period of three years. The composition of the microalgae community changed with salinity and temperature. In the shallow marginal zone the diatoms predominated in winter and spring, at salinities of 30–72 g‐1‐1and at temperatures not exceeding 30o°C, whereas in summer, cyanobacteria were the most abundant. In the deeper zone, at higher salinities and temperatures, cyanobacteria predominated throughout the year. The depth limit of algal growth was 60‐80cm, where salinity and temperature exceeded 211 g‐1‐1and 48°C.The most euryhaline and eurythermal among cyanobacteria wereAphanolhece halophyticaFremyandPhormidium hypolimneticumCampbell, among diatomsNitzschiasp. aff.N. rostellataHustedt,Amphora coffeaeformis(Agardh) Kutzing, andNavicula mas

ISSN:0173-9565    

DOI:10.1111/j.1439-0485.1987.tb00183.x

出版商:Blackwell Publishing Ltd    

年代:1987

数据来源: WILEY