1,720,990 research outputs found
Production of the meiobentic harpacticoid copepod Canuella perplexa
No full textSecondary production of C. perplexa was estimated in a brackish water lagoon of the Po River Delta (Italy). Three generation peaks and a nonproductive overwintering population were observed. Estimates of the annual production of copepodites and adults using 3 methods are similar: 6.76, 6.09 and 6.78 g dry wt m-2. Egg production was 0.02 g dry wt m-2; nauplii production was 0.38 g dry wt m-2. These values show a relatively constant P/B ratio per generation (3-4). -from Author
Growth and secondary production of the Mediterranean gorgonian Paramuricea clavata (Risso, 1826)
No full textGrowth and secondary production of the shallow water gorgonian Paramuricea clavata were investigated at an infralittoral rocky station located at the northern entrance of the Strait of Messina. Colonies were aged by counting the number of annual growth rings at the base of the skeleton. Mean annual growth rates were calculated both by field measurements and by fitting a Bertalanffy growth equation for the specie
Damage and partial mortality of the gorgonian Paramuricea clavata in the Strait of Messina (Tyrrhenian Sea)
No full textA massive development of mucilage and a case of partial mortality in the Mediterranean gorgonian Paramuricea clavata is reported..
Growth of the Mediterranean GorgonianLophogorgia ceratophyta(L., 1758)
No full textGrowth of the shallow-water gorgonian Lophogorgia ceratophyta was investigated in an infralittoral station located in La Spezia Gulf, Ligurian Sea. Mean annual height growth rate was estimated to be 2.57 cm · a-1. The fractal dimension of the colonies was found to gradually evolve in complexity, exhibiting a simpler branching pattern in younger specimens. The maintenance of a low, invariable ramification complexity as an optimal choice in managing relationships between water and the colony's living tissues is also discussed
Ecological and zoogeographical study of some mediterranean associations of brackish water harpacticoids
No full textAbundance data of harpacticoid species collected during meio- faunistic surveys in five Italian brackish environments have been analyzed. Comparisons among lagoon species assemblages were subjected to classification and ordination procedures. Additional lists of harpacticoid species from Mediterranean and Pontic brackish lagoons were assembled from the literature and further comparisons were made among the ten harpacticoid associations on the basis of binary presence-absence data. On a limited distance scale, e.g. the case of the five Italian lagoons, ecological factors, such as the sheltering degree and the extension of the phytal habitat, probably play a predominant role in structuring faunistic associations. On a larger distance scale, e.g. the case of the ten Mediterranean and Pontic lagoons, distributional patterns seem to be more related to zoogeographical factors. Late Quaternary eustatic events are invoked to explain the zoogeographical affinities among Pontic and Adriatic brac..
Predaction impact on meiobenthic harpacticoid Canuella perplexa in a lagoon of the Po River Delta, Italy
No full textThe impact of predation by juvenile marble gobies, Pomatoschistus marmoratus, on the meiobenthic harpacticoid copepod Canuella perplexa was investigated at a subtidal station located in a shallow-water, brackish embayment of the Po river delta, in summer and fall 1978. In august, predation mainly centered on adults, with a very large number of prey for each predator
Growth and Production of the Ark Shell Scapharca inaequlvalvis (BRUGUIÈRE) in a Lagoon of the Po River Delta
No full textScapharca inaequivalvis is an Indopacific bivalve which has recently immigrated to the Adriatic Sea and has progressively replaced dominant species within the infauna communities..
Life cycles and feeding habits of Syngnathus taenionotus and S. abaster (Pisces, Syngnathidae) in a brackish bay of the Po River Delta (Adriatic Sea).
No full textThese species inhabit the nearshore environment of the bay where the sandy bottom is covered by macroalgae. The main differences in life history traits between S. taenionotus and S. abaster respectively can be summarized as follows: life span is c24 vs 17 mo; reproductive season begins in February vs March, and lasts 5 vs 4 mo; average length of fingerlings at the time they hatch from the male brood pouch is 20.3(±1.2) vs 13.5(±1.0) mm; egg incubation period is 2 mo vs 1 mo; average number of ripe eggs per mature ovary is 46(±9) vs 104(±40); average number of embryos incubated by male is 84(±17) vs 109(±27). The sex ratio in the reproductive population is more male-biased in S. taenionotus. The two species probably do not compete for food resources, remaining almost completely segregated in different foraging micro-habitats during most of their life span. The new-born spring individuals of both species feed almost exclusively on harpacticoids of the genus Tisbe. As they mature, S. abaster continue to prey on phytal organisms while the larger S. taenionotus become zooplanktivorous. -from Author
Development of a fuzzy-Bayesian joint approach to ecosystem analysis and modelling: application to coastal marine ecosystem
Full text linkNell’attuale contesto di aumento degli impatti antropici e di “Global Climate Change” emerge la necessità di comprenderne i possibili effetti di questi sugli ecosistemi inquadrati come fruitori di servizi e funzioni imprescindibili sui quali si basano intere tessiture economiche e sociali. Lo studio previsionale degli ecosistemi si scontra con l’elevata complessità di questi ultimi in luogo di una altrettanto elevata scarsità di osservazioni integrate. L’approccio modellistico appare il più adatto all’analisi delle dinamiche complesse degli ecosistemi ed alla contestualizzazione complessa di risultati sperimentali ed osservazioni empiriche. L’approccio riduzionista-deterministico solitamente utilizzato nell’implementazione di modelli non si è però sin qui dimostrato in grado di raggiungere i livelli di complessità più elevati all’interno della struttura eco sistemica. La componente che meglio descrive la complessità ecosistemica è quella biotica in virtù dell’elevata dipendenza dalle altre componenti e dalle loro interazioni. In questo lavoro di tesi viene proposto un approccio modellistico stocastico basato sull’utilizzo di un compilatore naive Bayes operante in ambiente fuzzy. L’utilizzo congiunto di logica fuzzy e approccio naive Bayes è utile al processa mento del livello di complessità e conseguentemente incertezza insito negli ecosistemi. I modelli generativi ottenuti, chiamati Fuzzy Bayesian Ecological Model(FBEM) appaiono in grado di modellizare gli stati eco sistemici in funzione dell’ elevato numero di interazioni che entrano in gioco nella determinazione degli stati degli ecosistemi. Modelli FBEM sono stati utilizzati per comprendere il rischio ambientale per habitat intertidale di spiagge sabbiose in caso di eventi di flooding costiero previsti nell’arco di tempo 2010-2100. L’applicazione è stata effettuata all’interno del progetto EU “Theseus” per il quale i modelli FBEM sono stati utilizzati anche per una simulazione a lungo termine e per il calcolo dei tipping point specifici dell’habitat secondo eventi di flooding di diversa intensità.In the current environmental context, it emerges the need to understand all the possible effects of the increase of the anthropic impact and the “Global Climate Change” on the ecosystems, considered as the main users of services and essential functions upon which whole economic and social textures are based. The forecast study of the ecosystems collides with the high complexity of them and with the lack of integrated observations. The model approach seems to be the most appropriate for the analysis of the complex dynamics of the ecosystems and the contextualization of experimental results and empiric observations. The reductionist-deterministic approach, which generally is used in the implementation of the models, has not been able to reach higher levels of complexity within the structure of the ecosystem. The biotic factor is the component that best describes the complexity of the ecosystem, because of the high dependency upon the other components and their interactions. In this thesis, it is suggested a new stochastic and model approach based on the employment of a naive-Bayesian compiler operating within a fuzzy environment. The combined employment of fuzzy logic and naive-Bayesian approach is useful to process the high degree of uncertainty of the ecosystems. The obtained generative models, called Fuzzy Bayesian Ecological Models (FBEM) are able to modelize the states of the ecosystems as functions of the high number of interactions. FBEM models have been used to understand the environmental risk for the intertidale habitat of sand beaches in case of coast flooding events forecasted from 2010 to 2100. The application has been developed within the EU “Theseus” Project, in which the FBEM models have been used also for a long term simulation and for the computation of the tipping points specific of the habitat depending on flooding events of different intensity
- …
