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Colonisation process of vegetative fragments of Posidonia oceanica (L.) Delile on rubble mounds

Colonisation process of vegetative fragments of Posidonia oceanica (L.) Delile on rubble mounds
Colonisation process of vegetative fragments of Posidonia oceanica (L.) Delile on rubble mounds
Seagrass colonise new areas via the dispersion of seeds or vegetative fragments. Independent of the manner of colonization, habitat requirements need to be met for the successful establishment of seagrasses. Here we report on the colonization process of Posidonia oceanica in a highly disturbed area: a gas pipeline trench at Capo Feto (SW Sicily, Italy). A trench dredged through a P. oceanica bed was back-filled with rubble added from dump barges leading to the formation of a series of rubble mounds on the seabed. Over time, these mounds became colonised with P. oceanica. I>. In order to understand the pattern of P. oceanica colonization, shoot density was quantified over 3 years (2001–2003) on different mound locations (crests, sides, valleys). Seagrass coalescence was observed only in valleys between mounds where shoot density averaged 133±50 shoots m?2, while values for sides and crests were significantly lower (30.5±14 and 5.8±2.6 shoots m?2, respectively). Although sediment accumulated on both crests and valleys, a significantly thicker sediment layer was recorded in the valleys (9.8±0.4 cm) than on crests (1.1±0.2). Plaster dissolution rate (an indicator of the hydrodynamic regime) tended to decrease from crests to valleys but even in the valleys, the currents were still higher than in the adjacent vegetated control location. This pattern was constant over time and depths. This is the first study to report on P. oceanica vegetative recruitment on artificial rubble after a disturbance event. It appears that the valleys between the rubble mounds are suitable for seagrass recruitment as sediment deposited between the rubble provides the necessary resources for plant settlement and growth. Once the seagrass patches are established, they may start a positive feedback of attenuation of currents, sediment accumulation and seagrass patch expansion.
0025-3162
1261-1270
Di Carlo, G.
d07b9560-30e8-4070-99a0-40b87ae91bcc
Badamenti, F.
09b770ff-f53b-4e57-aff0-1afb22657b65
Jensen, A.C.
ff1cabd2-e6fa-4e34-9a39-5097e2bc5f85
Koch, E.W.
01ca0074-0659-4d16-be47-7e358b71cdfb
Riggio, S.
81a49916-d088-4797-937a-346d08e4b466
Di Carlo, G.
d07b9560-30e8-4070-99a0-40b87ae91bcc
Badamenti, F.
09b770ff-f53b-4e57-aff0-1afb22657b65
Jensen, A.C.
ff1cabd2-e6fa-4e34-9a39-5097e2bc5f85
Koch, E.W.
01ca0074-0659-4d16-be47-7e358b71cdfb
Riggio, S.
81a49916-d088-4797-937a-346d08e4b466

Di Carlo, G., Badamenti, F., Jensen, A.C., Koch, E.W. and Riggio, S. (2005) Colonisation process of vegetative fragments of Posidonia oceanica (L.) Delile on rubble mounds. Marine Biology, 147 (6), 1261-1270. (doi:10.1007/s00227-005-0035-0).

Record type: Article

Abstract

Seagrass colonise new areas via the dispersion of seeds or vegetative fragments. Independent of the manner of colonization, habitat requirements need to be met for the successful establishment of seagrasses. Here we report on the colonization process of Posidonia oceanica in a highly disturbed area: a gas pipeline trench at Capo Feto (SW Sicily, Italy). A trench dredged through a P. oceanica bed was back-filled with rubble added from dump barges leading to the formation of a series of rubble mounds on the seabed. Over time, these mounds became colonised with P. oceanica. I>. In order to understand the pattern of P. oceanica colonization, shoot density was quantified over 3 years (2001–2003) on different mound locations (crests, sides, valleys). Seagrass coalescence was observed only in valleys between mounds where shoot density averaged 133±50 shoots m?2, while values for sides and crests were significantly lower (30.5±14 and 5.8±2.6 shoots m?2, respectively). Although sediment accumulated on both crests and valleys, a significantly thicker sediment layer was recorded in the valleys (9.8±0.4 cm) than on crests (1.1±0.2). Plaster dissolution rate (an indicator of the hydrodynamic regime) tended to decrease from crests to valleys but even in the valleys, the currents were still higher than in the adjacent vegetated control location. This pattern was constant over time and depths. This is the first study to report on P. oceanica vegetative recruitment on artificial rubble after a disturbance event. It appears that the valleys between the rubble mounds are suitable for seagrass recruitment as sediment deposited between the rubble provides the necessary resources for plant settlement and growth. Once the seagrass patches are established, they may start a positive feedback of attenuation of currents, sediment accumulation and seagrass patch expansion.

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Published date: 2005

Identifiers

Local EPrints ID: 20386
URI: http://eprints.soton.ac.uk/id/eprint/20386
ISSN: 0025-3162
PURE UUID: 8e7488a4-1430-4a90-bc34-35831029002a
ORCID for A.C. Jensen: ORCID iD orcid.org/0000-0002-8924-1198

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Date deposited: 23 Feb 2006
Last modified: 16 Mar 2024 02:34

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Contributors

Author: G. Di Carlo
Author: F. Badamenti
Author: A.C. Jensen ORCID iD
Author: E.W. Koch
Author: S. Riggio

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