1,721,269 research outputs found
The "stinging" egg of Clavopsella michaeli (Hydrozoa, Cnidaria).
No full textThe bougainvillid hydroid Clavopsella micbaeli produces clubshaped female gonophores each bearing up to eight large eggs. These eggs are covered by a single layer of isolated cnidocytes in close contact with the oocyte membrane. These cnidocytes have fully-developed microbasic curytele cnidocysts always in functional position, with the cnidocil apex pointed outwards. The cnidocysts constitute a defensive «stinging armor» protecting the large eggs
Ecology, life cycle variability and reproductive biology of deep-sea polychaetes (Aphroditidae, Polynoidae, Sabellidae)
No full textThe non-Siphonophoran Hydrozoa (Cnidaria) of Salento, Italy with notes on their life-cycles: an illustrated guide
Full text linkGravili, Cinzia, Vito, Doris De, Camillo, Cristina Gioia Di, Martell, Luis, Piraino, Stefano, Boero, Ferdinando (2015): The non-Siphonophoran Hydrozoa (Cnidaria) of Salento, Italy with notes on their life-cycles: an illustrated guide. Zootaxa 3908 (1): 1-187, DOI: 10.11646/zootaxa.3908.1.
The adaptive pattern of growth and reproduction of the colonial hydroid Clavopsella michaeli (Berrill, 1948). HYDROBIOLOGIA
No full textThe effects of variations in temperature, salinity and water movement on the laboratory growth and
reproduction of a single clone of the bougainvilliid hydroid Clavopsella michaeli were examined. Unfavourable
conditions resulted in reproducible oscillations of growth rate. They ranged from overall stimulatory
effects (hormesis) to irreversible inhibition and shrinkage of colonies. Exposure to low concentrations
(0.1-5 jug 1- ') of copper and mercury ions produced similar responses, which were therefore regarded
as non-specific. A control mechanism, dampening these growth rate oscillations, supported higher
colonial tolerance, that is adaptation, to environmental stresses of low intensity. When the counteractive
capacity of the control mechanism was exceeded, inhibition occurred. Higher frequencies of gonozooids
were observed in stressed colonies and were interpreted as an adaptive response
On two Eudendrium (Cnidaria, Hydrozoa) species from the Mediterranean Sea
Full text linkTwo species referable to the genus Eudendrium Ehrenberg are recorded from the central Mediterranean Sea. Eudendrium merulum is reported for the jirst time outside
Australia, whereas Eudendrium carneum is recorded for the second time from Mediterranean
waters. The structure of the nematocysts of E. merulum is elucidated by SEM analyses and the mechanism of penetration is compared to that of other hydroid
Biodiversità funzionale, ridondanza e specie cardine
No full textRelazione ad invito al XXVII Congresso della Società Italiana di Biologia Marina, Portoferraio - Isola d’Elba 20-25 Maggio 199
Keystone Species: What Are We Talking About?
Full text linkScience is often challenged by misuse of terminology. In most cases, this is due to an incomplete review of the literature. In spite of recent recommendations (Paine 1996), terms like "species' functional roles" are still used in a confused way, and original definitions are often misinterpreted. The "keystone species" concept (Paine 1966, 1969) is a case in point. In recent years, the overly expansive usage of the keystone concept has led to a redefinition of the term. According to the current interpretation (Power and Mills 1995, Power et al. 1996), keystones are only those species having a large, disproportionate effect, with respect to their biomass or abundance, on their community. Some operational tools are now available to distinguish not only between strong and weak interactors, but also between keystone and dominant species (Paine 1992, Navarrete and Menge 1996, Power et al. 1996, Hurlbert 1997). Khanina (1998) is the latest (but certainly not the last) author attributing the keystone status to dominant species or even to dominants with structural roles (see, for instance, MacIsaac et al. 1995, Procaccini et al. 1996, Hacker and Gaines 1997). Moreover, those species driving ecosystem processes or energy flows are generally referred as "key" species, but only a few of them are keystones. Putting keystones and key species in the same melting pot, as Khanina (1998) does, should be avoided. Therefore, trees and bisons are not keystones, just as the original keystone species identified by Paine was not the dominant mussel, but its starfish predator
Zonation and ecology of epiphytic hydroids in a Mediterranean coastal lagoon: the Stagnone of Marsala (NW Sicily). P.S.Z.N. I: Marine Ecology, 11 (1),
No full textDistribution patterns of epiphytic hydroids of seagrass (Posidonia oceanica and Cymodocea nodosa) beds were studied in a moderately hyperhaline lagoon
MOLTOOLS: a workshop on “Molecular tools for monitoring marine invasive species”
No full textThe 2011-2014 European Community project VECTORS (“Vectors of Change in Oceans and Seas-Marine Life, Impact on Economic Sectors”) was an integrated, multidisciplinary European project which aimed to improve our understanding of how environmental anthropogenic drivers are impacting European marine ecosystems now and in the future. VECTORS investigated how these changes may affect marine biodiversity and ecosystem functioning, the range of goods and services provided by the oceans, the resulting socio-economic impacts and some possible future scenarios for mitigation and adaptation
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