Eudendrium racemosum (Cavolini 1785) is an athecate hydrozoan widely distributed in the Mediterranean basin, characterized by phenotypic plasticity and high environmental sensitivity, resulting as a suitable indicator taxon for assessing the impacts of climate change. It is a seasonal species, present during the warm season and entering a state of dormancy during winter. In this study, the population structure of E. racemosum at the "Scoglio del Trave" site, located along the Conero Riviera, was characterized over a three-month period from May to July 2025. Through monthly underwater sampling and subsequent laboratory analyses, temporal variations in colony area, the abundance of different zooid types, and the sex ratio were evaluated. Additionally, the categorization and counting of the associated fauna were carried out. Data were processed using software such as Excel and RStudio. The results demonstrate a progressive and significant increase in colony size coinciding with the gradual seasonal rise in temperature. Structurally, a clear phenological transition was observed: an initial stage of development and biomass growth is followed by a maturation phase in which resources shift heavily toward reproduction. The associated biological community also exhibits dynamics highly synchronized with seasonal cycles, highlighting the role of these colonies as a nursery for bivalve recruitment and as a refuge for amphipods and other components of the meio- and macrofauna within the local trophic web. These findings support the species' role as an habitat former. A comparison with data from the study by Di Camillo et al. (2012) for the years 2007–2009 revealed a decrease in the mean colony area in the recent period, contrasted with a sharp increase in average water temperature. In June, a substantial increase in nutritive polyps was recorded compared to the past, and comparisons of the sex ratio revealed a shift in sex composition compared to 2008, with the simultaneous presence of assignment (co-occurrence) of males and females. The data from the May–July 2025 period, as part of a broader monitoring program, represent a baseline for future analyses of long-term trends of Eudendrium racemosum in the Adriatic basin. The ultimate goal is to improve the monitoring of population changes and to further investigate the interspecific relationships with the associated fauna.
Eudendrium racemosum (Cavolini 1785) è un idrozoo atecato ampiamente diffuso nel bacino Mediterraneo, caratterizzato da plasticità fenotipica ed elevata sensibilità ambientale che lo rendono un buon taxon indicatore per valutare gli effetti del cambiamento climatico. Si tratta di una specie a ciclo stagionale, presente durante la stagione calda, mentre entra in una fase di dormienza durante l’inverno. In questo lavoro è stata delineata la struttura di popolazione di E. racemosum localizzata nel sito “Scoglio del Trave”, situato lungo la Riviera del Conero, nel trimestre maggio-luglio 2025. Attraverso campionamenti subacquei mensili e successive analisi operate in laboratorio, sono state valutate le variazioni temporali dell'area delle colonie, l'abbondanza delle diverse tipologie di zooidi e la sex ratio. In aggiunta, è stata svolta anche la categorizzazione e conta della fauna associata. I dati sono stati elaborati tramite l’utilizzo di software quali Excel ed Rstudio. I risultati mostrano una progressiva e rilevante crescita dimensionale delle colonie in concomitanza con il progressivo innalzamento termico stagionale. Sotto il profilo strutturale, è stata evidenziata una chiara transizione fenologica: a una fase iniziale di sviluppo e accrescimento della biomassa, segue una fase di maturazione in cui le risorse virano massicciamente verso la riproduzione. Anche la comunità biologica ospitata mostra dinamiche fortemente sincronizzate con i cicli stagionali, evidenziando il ruolo delle colonie come “nursery” per il reclutamento di bivalvi e come rifugio per anfipodi e componenti della meio- e macrofauna all'interno della rete trofica locale, supportando il ruolo della specie come “habitat former”. Il confronto con i dati dello studio svolto da Di Camillo et al. (2012) relativo agli anni 2007-2009 ha rivelato una diminuzione dell'area media delle colonie nel periodo recente, a fronte di un netto incremento della temperatura media dell'acqua. A giugno è stato registrato un elevato aumento dei polipi nutritivi rispetto al passato e dai confronti relativi alla sex ratio è emerso un cambio nella composizione dei sessi rispetto al 2008 con simultaneità di maschi e femmine. I dati del trimestre maggio-luglio 2025, parte di un monitoraggio più ampio, pongono le basi per future analisi sui trend a lungo termine di Eudendrium racemosum nel bacino Adriatico. Il fine è quello di monitorare al meglio i cambiamenti della popolazione ed approfondire le relazioni interspecifiche con la fauna associata.
STRUTTURA DI POPOLAZIONE DI EUDENDRIUM RACEMOSUM (CAVOLINI 1785) DELLA RIVIERA DEL CONERO
ROSTIROLLA, ELISA
2025/2026
Abstract
Eudendrium racemosum (Cavolini 1785) is an athecate hydrozoan widely distributed in the Mediterranean basin, characterized by phenotypic plasticity and high environmental sensitivity, resulting as a suitable indicator taxon for assessing the impacts of climate change. It is a seasonal species, present during the warm season and entering a state of dormancy during winter. In this study, the population structure of E. racemosum at the "Scoglio del Trave" site, located along the Conero Riviera, was characterized over a three-month period from May to July 2025. Through monthly underwater sampling and subsequent laboratory analyses, temporal variations in colony area, the abundance of different zooid types, and the sex ratio were evaluated. Additionally, the categorization and counting of the associated fauna were carried out. Data were processed using software such as Excel and RStudio. The results demonstrate a progressive and significant increase in colony size coinciding with the gradual seasonal rise in temperature. Structurally, a clear phenological transition was observed: an initial stage of development and biomass growth is followed by a maturation phase in which resources shift heavily toward reproduction. The associated biological community also exhibits dynamics highly synchronized with seasonal cycles, highlighting the role of these colonies as a nursery for bivalve recruitment and as a refuge for amphipods and other components of the meio- and macrofauna within the local trophic web. These findings support the species' role as an habitat former. A comparison with data from the study by Di Camillo et al. (2012) for the years 2007–2009 revealed a decrease in the mean colony area in the recent period, contrasted with a sharp increase in average water temperature. In June, a substantial increase in nutritive polyps was recorded compared to the past, and comparisons of the sex ratio revealed a shift in sex composition compared to 2008, with the simultaneous presence of assignment (co-occurrence) of males and females. The data from the May–July 2025 period, as part of a broader monitoring program, represent a baseline for future analyses of long-term trends of Eudendrium racemosum in the Adriatic basin. The ultimate goal is to improve the monitoring of population changes and to further investigate the interspecific relationships with the associated fauna.| File | Dimensione | Formato | |
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Eudendrium racemosum Elisa Rostirolla.pdf
embargo fino al 23/01/2028
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https://hdl.handle.net/20.500.12075/27947