Nicoletta MANCIN, GUASTELLA R., CARLTON J. T., COBIANCHI M., EVANS J.,
CAPOTONDI L., LANGONE L., MARCHINI A.
Dipartimento di Scienze della Terra e dell’Ambiente, Università di Pavia, Via Ferrata 1,
27100, Pavia, Italy
E-mail: agnese.marchini@unipv.it
AN EARLY INVASION INTERRUPTED BY A TSUNAMI: THE
CASE OF AMPHISTEGINA LOBIFERA (FORAMINIFERA) IN
MALTA, CENTRAL MEDITERRANEAN SEA
Abstract
Information on early invasion stages, whether successful or not, is often lacking because most
invaders are discovered only once they have become abundant or have caused appreciable
changes to the recipient environment. Moreover, when newcomers fail to establish selfsustaining populations, they are often not even documented.
Here we report an early invasion detected from two sediment cores radiometrically dated
through
210
Pb chronology, collected in the Marsamxett harbour of Malta. The cores record at
least the last 110 years and contain specimens of the Indo-Pacific benthic foraminifer
Amphistegina lobifera Larsen 1976; showing that the species was already present in Malta at
the beginning of the 20th century, but then it abruptly disappeared. We hypothesise that the
disappearance was triggered by the 1908 Messina earthquake, with the following scenario: an
anomalous tsunami wave reached the Marsamxett harbour and deposited over 20 cm of
sediment. This depositional event suddenly buried the sea-bottom and its benthic community.
Today, A. lobifera is abundant along the Maltese coast, likely as a result of a re-invasion.
Key-words: Foraminifera, invasion, sediment core
Introduction
Many factors have been suggested to drive the success or failure of biological invasions,
among which propagule pressure and genetic structure of the introduced population,
habitat match between source and recipient regions, biotic resistance of native
communities (through competition, predation and parasitism interactions).
Unfortunately, the early stages of invasion, when the newly introduced population is
facing all these challenges, are particularly difficult to detect and study: new species, in
fact, are often noticed only after having developed well-established populations,
especially in marine habitats and when small-sized taxa are concerned. The
understanding of timing of first introductions and early stages invasion processes is
therefore limited. A variety of approaches have been used to compensate for this gap
and try to reconstruct the colonization history of alien species: reexamination of old
museum collections (e.g. Ahnelt, 2016), analysis of published descriptions (e.g. Zullo,
1992), interviews to local fishermen (e.g. Bariche et al., 2014), molecular tools (e.g.
Deldicq et al. 2019) and radiometric dating (e.g. Petersen et al., 1992; Albano et al.,
2018). In particular, the analysis of historical records preserved in sediment cores allows
to reconstruct the colonization history of alien species and to identify the first
introduction events, as well as possible early failed invasions.
In this study, we document a peculiar case of early introduction, followed by an abrupt
failed invasion, occurred over one century ago in the Central Mediterranean Sea after a
2nd Mediterranean Symposium on the Non-Indigenous Species (Genoa, Italy, 22-23 September 2022)
50
CAPOTONDI L., LANGONE L., MARCHINI A.
Dipartimento di Scienze della Terra e dell’Ambiente, Università di Pavia, Via Ferrata 1,
27100, Pavia, Italy
E-mail: agnese.marchini@unipv.it
AN EARLY INVASION INTERRUPTED BY A TSUNAMI: THE
CASE OF AMPHISTEGINA LOBIFERA (FORAMINIFERA) IN
MALTA, CENTRAL MEDITERRANEAN SEA
Abstract
Information on early invasion stages, whether successful or not, is often lacking because most
invaders are discovered only once they have become abundant or have caused appreciable
changes to the recipient environment. Moreover, when newcomers fail to establish selfsustaining populations, they are often not even documented.
Here we report an early invasion detected from two sediment cores radiometrically dated
through
210
Pb chronology, collected in the Marsamxett harbour of Malta. The cores record at
least the last 110 years and contain specimens of the Indo-Pacific benthic foraminifer
Amphistegina lobifera Larsen 1976; showing that the species was already present in Malta at
the beginning of the 20th century, but then it abruptly disappeared. We hypothesise that the
disappearance was triggered by the 1908 Messina earthquake, with the following scenario: an
anomalous tsunami wave reached the Marsamxett harbour and deposited over 20 cm of
sediment. This depositional event suddenly buried the sea-bottom and its benthic community.
Today, A. lobifera is abundant along the Maltese coast, likely as a result of a re-invasion.
Key-words: Foraminifera, invasion, sediment core
Introduction
Many factors have been suggested to drive the success or failure of biological invasions,
among which propagule pressure and genetic structure of the introduced population,
habitat match between source and recipient regions, biotic resistance of native
communities (through competition, predation and parasitism interactions).
Unfortunately, the early stages of invasion, when the newly introduced population is
facing all these challenges, are particularly difficult to detect and study: new species, in
fact, are often noticed only after having developed well-established populations,
especially in marine habitats and when small-sized taxa are concerned. The
understanding of timing of first introductions and early stages invasion processes is
therefore limited. A variety of approaches have been used to compensate for this gap
and try to reconstruct the colonization history of alien species: reexamination of old
museum collections (e.g. Ahnelt, 2016), analysis of published descriptions (e.g. Zullo,
1992), interviews to local fishermen (e.g. Bariche et al., 2014), molecular tools (e.g.
Deldicq et al. 2019) and radiometric dating (e.g. Petersen et al., 1992; Albano et al.,
2018). In particular, the analysis of historical records preserved in sediment cores allows
to reconstruct the colonization history of alien species and to identify the first
introduction events, as well as possible early failed invasions.
In this study, we document a peculiar case of early introduction, followed by an abrupt
failed invasion, occurred over one century ago in the Central Mediterranean Sea after a
2nd Mediterranean Symposium on the Non-Indigenous Species (Genoa, Italy, 22-23 September 2022)
50