| Title | Testing the saprobity hypothesis in a Mediterranean lagoon: Effects of confinement and organic enrichment on benthic communities |
| Abstract | The macrobenthic community was compared at four sites characterized by varying degrees of freshwater input, organic enrichment and confinement in the Cabras lagoon (Sardinia, Italy). Three sites, riverine (Cl), confined (C2) and seaward (C3), were studied on two dates of summer 2010 and on two dates of winter 2011. A fourth site (C12), representative of the central sector of the Cabras lagoon, was included in this study using the extensive historical datasets at our disposal from previously published work. We aimed to test the hypothesis that (1) the benthos is distributed according to the recently proposed concept of habitat saprobity for coastal lagoons that unifies the Pearson Rosenberg (sensu organic enrichment) and Guelorget-Perthuisot (sensu confinement) models, and (2) indicator species of different saprobic levels can be identified among dominant species occurring along the saprobity gradient. Salinity was also considered as an additional agent of selection in brackish environments. Irrespective of significant seasonal changes within each site, our results highlighted major environmental and biotic differences between sites. At the northward riverine site (Cl), most affected by freshwater input and with limited organic matter (OM) enrichment, Corophium orientate was the single dominant species. The most confined site (C2) was characterized by the highest levels of sedimentary OM and benthic Chlorophyll-a and by mesohaline conditions; the site was inhabited mainly by the halolimnobic Hediste diversicolor and Hydrobia spp. Site C12, characterized by a high OM load and high residence time, was dominated by the opportunistic detritivorous Alitta succinea and Polydora ciliata. At the southern-most seaward site (C3) the considerable seawater renewal, resulting in high salinity (only in summer) and limited OM load, favored a much more diverse macrobenthic assemblage, essentially composed of both marine species, such as Corophium insidiosum, Gammarus aequicauda, and brackish-water species, such as Lekanesphaera hookeri and Idotea chelipes. We conclude that the biotic and abiotic characteristics of the Cabras lagoon can be represented by a succession of spatial zones along two main gradients determined by salinity and saprobity. The salinity gradient proved to be the main structural feature in the oligohaline pole, while in the range of variable salinity, saprobity appeared to be the main selection factor. To illustrate our findings, we provide a graphical representation summarizing the changes in environmental parameters and indicator species along the salinity and saprobity gradients. (C) 2014 Elsevier Ltd. All rights reserved. |
| Source | Marine environmental research 99, pp. 85–94 |
| Keywords | MacrobenthosBrackish watersOrganic enrichmentSaprobitySalinityMediterranean lagoons |
| Journal | Marine environmental research |
| Editor | Applied Science Publishers,, Barking, Regno Unito |
| Year | 2014 |
| Type | Articolo in rivista |
| DOI | 10.1016/j.marenvres.2014.04.004 |
| Authors | Foti, A.; Fenzi, G. A.; Di Pippo, F.; Gravina, M. F.; Magni, P. |
| Text | 298905 2014 10.1016/j.marenvres.2014.04.004 ISI Web of Science WOS 000340699600011 Macrobenthos Brackish waters Organic enrichment Saprobity Salinity Mediterranean lagoons Testing the saprobity hypothesis in a Mediterranean lagoon Effects of confinement and organic enrichment on benthic communities Foti, A.; Fenzi, G. A.; Di Pippo, F.; Gravina, M. F.; Magni, P. University of Rome Tor Vergata; Consiglio Nazionale delle Ricerche CNR ; Consiglio Nazionale delle Ricerche CNR ; Consiglio Nazionale delle Ricerche CNR The macrobenthic community was compared at four sites characterized by varying degrees of freshwater input, organic enrichment and confinement in the Cabras lagoon Sardinia, Italy . Three sites, riverine Cl , confined C2 and seaward C3 , were studied on two dates of summer 2010 and on two dates of winter 2011. A fourth site C12 , representative of the central sector of the Cabras lagoon, was included in this study using the extensive historical datasets at our disposal from previously published work. We aimed to test the hypothesis that 1 the benthos is distributed according to the recently proposed concept of habitat saprobity for coastal lagoons that unifies the Pearson Rosenberg sensu organic enrichment and Guelorget Perthuisot sensu confinement models, and 2 indicator species of different saprobic levels can be identified among dominant species occurring along the saprobity gradient. Salinity was also considered as an additional agent of selection in brackish environments. Irrespective of significant seasonal changes within each site, our results highlighted major environmental and biotic differences between sites. At the northward riverine site Cl , most affected by freshwater input and with limited organic matter OM enrichment, Corophium orientate was the single dominant species. The most confined site C2 was characterized by the highest levels of sedimentary OM and benthic Chlorophyll a and by mesohaline conditions; the site was inhabited mainly by the halolimnobic Hediste diversicolor and Hydrobia spp. Site C12, characterized by a high OM load and high residence time, was dominated by the opportunistic detritivorous Alitta succinea and Polydora ciliata. At the southern most seaward site C3 the considerable seawater renewal, resulting in high salinity only in summer and limited OM load, favored a much more diverse macrobenthic assemblage, essentially composed of both marine species, such as Corophium insidiosum, Gammarus aequicauda, and brackish water species, such as Lekanesphaera hookeri and Idotea chelipes. We conclude that the biotic and abiotic characteristics of the Cabras lagoon can be represented by a succession of spatial zones along two main gradients determined by salinity and saprobity. The salinity gradient proved to be the main structural feature in the oligohaline pole, while in the range of variable salinity, saprobity appeared to be the main selection factor. To illustrate our findings, we provide a graphical representation summarizing the changes in environmental parameters and indicator species along the salinity and saprobity gradients. C 2014 Elsevier Ltd. All rights reserved. 99 Articolo in rivista Applied Science Publishers, 0141 1136 Marine environmental research Marine environmental research Mar. environ. res. Marine environmental research. Journal of marine environmental research paolo.magni MAGNI PAOLO francesca.dipippo DI PIPPO FRANCESCA TA.P05.015.003 Processi ambientali e valutazione della qualita negli ambienti di transizione |
