Ioannis RALLIS, DIGENIS M., GEROVASILEIOU V., GRATSIA E.,
CHATZIGEORGIOU G.
Hellenic Centre for Marine Research (HCMR), Institute of Marine Biology,
Biotechnology and Aquaculture (IMBBC), 71500 Heraklion, Greece.
E-mail: i.rallis@hcmr.gr
ASSESSMENT OF SESSILE BENTHOS IN MARINAS OF GREECE
WITH A FOCUS ON NON-INDIGENOUS SPECIES
Abstract
Marinas receive a multitude of anthropogenic impacts such as marine pollution, high
turbulence and biological invasions via transport-stowaway and can function as stepping stones
for the dispersal of non-indigenous species (NIS). Although Greece has a high number of
marinas, little is known about their benthic communities. The current study aims to
quantitatively and qualitatively describe the benthic community patterns on artificial hard
substrates and to record NIS and cryptogenic species (CRY) found in four marinas across the
Greek Seas. Thus, during the last two years, a rapid assessment survey was applied in three
sampling events using non-destructive sampling (photoquadrats) while complementary
qualitative samples were also collected. In total, 45 photoquadrats were analyzed resulting in
significant differences in the community structure of the marinas, despite the highly similar
macroalgal coverage. Additionally, visual surveys provided new data regarding the presence of
twelve NIS and CRY, including four invasives. Additional sampling on a regular basis and
further investigation of the collected samples will provide a better understanding of this highly
affected ecosystem and can also be an effective tool for preventing secondary dispersion of NIS.
Key-words: Benthic communities, photoquadrats, hard substrate, marinas, alien species
Introduction
Greece constitutes a sea hub that unites five marine ecoregions (Adriatic Sea, Aegean
Sea, Levantine Sea, Ionian Sea and Black Sea, sensu Spalding et al., 2007).
Commercial, recreational and fishing vessels are active all year round while their hulls
and ballast waters act as a means of transport for many non-indigenous species (NIS)
(Zenetos et al., 2020). Sessile species can attach to the hulls of ships and reach various
marinas while ballast waters can carry various species’ larvae or grown individuals.
Several ports and marinas in Greece have been characterized as eutrophic environments
with a high number of anthropogenic pressures (Chatzinikolaou et al., 2018), generating
a strong impact on the local assemblages. A particular pressure occurring in marinas is
biological pollution, or, in other words, the presence of NIS, since they can overcome
environmental constraints and be frequent visitors (Nunes et al., 2014). Artificial
structures, such as docks and floating pontoons found in marinas, provide suitable
habitats to host opportunistic fouling species (Ferrario et al., 2017) and can function as
stepping stones for NIS’ dispersal in nearby natural habitats. In addition, the seawater
warming in the Mediterranean Sea (as a result of global climate change) seems to
enhance such NIS dispersal (Bianchi et al., 2019).
The present study was carried out in the framework of AlienPorts project
(https://alienports.hcmr.gr/) and focuses on four high maritime traffic marinas of
2nd Mediterranean Symposium on the Non-Indigenous Species (Genoa, Italy, 22-23 September 2022)
56
CHATZIGEORGIOU G.
Hellenic Centre for Marine Research (HCMR), Institute of Marine Biology,
Biotechnology and Aquaculture (IMBBC), 71500 Heraklion, Greece.
E-mail: i.rallis@hcmr.gr
ASSESSMENT OF SESSILE BENTHOS IN MARINAS OF GREECE
WITH A FOCUS ON NON-INDIGENOUS SPECIES
Abstract
Marinas receive a multitude of anthropogenic impacts such as marine pollution, high
turbulence and biological invasions via transport-stowaway and can function as stepping stones
for the dispersal of non-indigenous species (NIS). Although Greece has a high number of
marinas, little is known about their benthic communities. The current study aims to
quantitatively and qualitatively describe the benthic community patterns on artificial hard
substrates and to record NIS and cryptogenic species (CRY) found in four marinas across the
Greek Seas. Thus, during the last two years, a rapid assessment survey was applied in three
sampling events using non-destructive sampling (photoquadrats) while complementary
qualitative samples were also collected. In total, 45 photoquadrats were analyzed resulting in
significant differences in the community structure of the marinas, despite the highly similar
macroalgal coverage. Additionally, visual surveys provided new data regarding the presence of
twelve NIS and CRY, including four invasives. Additional sampling on a regular basis and
further investigation of the collected samples will provide a better understanding of this highly
affected ecosystem and can also be an effective tool for preventing secondary dispersion of NIS.
Key-words: Benthic communities, photoquadrats, hard substrate, marinas, alien species
Introduction
Greece constitutes a sea hub that unites five marine ecoregions (Adriatic Sea, Aegean
Sea, Levantine Sea, Ionian Sea and Black Sea, sensu Spalding et al., 2007).
Commercial, recreational and fishing vessels are active all year round while their hulls
and ballast waters act as a means of transport for many non-indigenous species (NIS)
(Zenetos et al., 2020). Sessile species can attach to the hulls of ships and reach various
marinas while ballast waters can carry various species’ larvae or grown individuals.
Several ports and marinas in Greece have been characterized as eutrophic environments
with a high number of anthropogenic pressures (Chatzinikolaou et al., 2018), generating
a strong impact on the local assemblages. A particular pressure occurring in marinas is
biological pollution, or, in other words, the presence of NIS, since they can overcome
environmental constraints and be frequent visitors (Nunes et al., 2014). Artificial
structures, such as docks and floating pontoons found in marinas, provide suitable
habitats to host opportunistic fouling species (Ferrario et al., 2017) and can function as
stepping stones for NIS’ dispersal in nearby natural habitats. In addition, the seawater
warming in the Mediterranean Sea (as a result of global climate change) seems to
enhance such NIS dispersal (Bianchi et al., 2019).
The present study was carried out in the framework of AlienPorts project
(https://alienports.hcmr.gr/) and focuses on four high maritime traffic marinas of
2nd Mediterranean Symposium on the Non-Indigenous Species (Genoa, Italy, 22-23 September 2022)
56