Resea ch Ideas and Ou comes 11: e172117
doi: 10.3897/ io.11.e172117
Re iewable 1
G an P oposal
Analysis o he causes and consequences o he
majo conce n on biodi e si y change in
He aklion BBT
G igo ios Skou adakis , Thanos Dailianis , Panayo a Koulou i
‡ Hellenic Cen e o Ma ine Resea ch, He aklion, C e e, G eece
Co esponding au ho : G igo ios Skou adakis (gskou adakis@hcm .g )
Recei ed: 15 Sep 2025 | Published: 06 Oc 2025
Ci a ion: Skou adakis G, Dailianis T, Koulou i P (2025) Analysis o he causes and consequences o he majo
conce n on biodi e si y change in He aklion BBT. Resea ch Ideas and Ou comes 11: e172117.
h ps://doi.o g/10.3897/ io.11.e172117
Abs ac
This s udy pe o ms a bow- ie analysis conce ning biodi e si y change in he B oad Bel
T ansec o He aklion Bay (BBT12) in he amewo k o MARBEFES p ojec . He aklion
Bay is cu en ly unde going changes mos ly due o clima e change, ou ism and
u banisa ion. This a ec s he ma ine en i onmen ia ma ine hea wa es, mass mo ali y
e en s and opicalisa ion. In oduc ion o in asi e species is on he ise in he a ea and
oge he wi h he ans o ma ion o ypical Medi e anean ocky ee s o ba en ee s is
leading o an ecosys em shi and signi ican changes in biodi e si y. In addi ion,
opicalisa ion can also be linked o he educ ion o ma ine biological esou ces a ec ing
he local ishe ies. Fu he mo e, ecen s udies o mac oben hic communi ies o so -
bo om habi a s in he a ea con ibu e o unde s anding he spa ial and empo al ends
and changes in biodi e si y due o mul iple en i onmen al and human-induced
dis u bances. These changes educe he ecosys emic esilience and can a ec
ecosys em se ices we ake o g an ed. Wi hin he amewo k o he p ojec , s akeholde s
o He aklion BBT ha e been su eyed and in e iewed and hei iews conce ning
balance be ween na u e, socie y and economy ha e also been inco po a ed in o he
bow- ie analysis. Thei main conce n o He aklion BBT is he ex ensi e de elopmen o
la ge-scale ou ism in he a ea. All hese p essu es ha e nega i e e ec s on he ma ine
‡ ‡ ‡
© Skou adakis G e al. This is an open access a icle dis ibu ed unde he e ms o he C ea i e Commons A ibu ion License
(CC BY 4.0), which pe mi s un es ic ed use, dis ibu ion, and ep oduc ion in any medium, p o ided he o iginal au ho and
sou ce a e c edi ed.
en i onmen o he a ea and socio-economic impac s on he popula ion o he a ea.
Ha ing his in mind, p e en ion and mi iga ion measu es a e p esen ed.
Keywo ds
He aklion BBT, la ge-scale ou ism, clima e change, in asi e species
In oduc ion
He aklion BBT co e s he en i e bay o He aklion also including Dia Island and i s coas s,
which is loca ed 10 km o sho e om he coas o He aklion Ci y. He aklion Bay consis s
mainly o so -bo om habi a s (sand and mud) and eaches dep hs exceeding 200 m.
Howe e , oughly hal o he coas line o he He aklion BBT is ocky ugged e ain ha
d ops in o he sea o ming Medi e anean ocky ee s which can be subs an ial locally.
Typical eas e n Medi e anean condi ions p e ail in he Bay, wi h p ima y p oduc i i y
being low (80 gC/m /yea ) and he a ea cha ac e ised as oligo ophic (Psa a e al. 2000
), ela i ely una ec ed by eshwa e un-o om i e s o was ewa e discha ges
(Koukouna i e al. 2020).
Se e al s udies ha e in es iga ed he mac oben hic aunal communi ies o he so -
bo om habi a s o He aklion Bay (Ka akassis and Ele he iou 1997, Plai i e al. 2000,
Tselepides e al. 2000, Koulou i e al. 2006, Koulou i e al. 2013, Tsikopoulou e al. 2019).
Howe e , hese s udies ha e been spo adic and long- e m da a a e limi ed, es ic ing
ou unde s anding o empo al ecological shi s ha could be a ec ing hose habi a s due
o en i onmen al and human-induced dis u bances and especially clima e change.
Addi ionally, es ablished non-indigenous ish and ben hic species a e ound in la ge
numbe s in he Bay (Ka sane akis 2020, Ragkousis 2023), exe ing p essu e in a a ie y
o habi a s. The wo Siganid species o abbi ish ha e o e g azed ( o mo e han wo
decades) he ocky ee s o he Bay leading o he shi om mac oalgae-domina ed ee s
o ba en ee s. In addi ion, o he non-indigenous g aze s like Diadema se osum u he
inc ease he o e g azing p essu e on he ocky ee s. New species a e con inuously
epo ed in He aklion Bay and oge he wi h he ising wa e empe a u e a e con ibu ing
o he p essu e on he habi a o he a ea h ough opicalisa ion (Za zyczny e al. 2024).
To b idge he gap be ween esea ch, policy and p ac ice, he p ojec is ocused on
s akeholde s whose expe iences and in e es s can be conside ed and ep esen ed in he
decision-making ools and ins umen s. To his end, ep esen a i es om a ange o
di e en sec o s (public audience, public au ho i ies, indus y/p i a e sec o , academia/
esea ch) ha e been in i ed o become in ol ed in MARBEFES and sha e hei poin o
iew ega ding He aklion BBT. Be ween 3 and 7 Ap il 2023, in e iews and su eys we e
conduc ed wi h 18 di e en ypes o s akeholde s (30 indi iduals) om he ou abo e-
men ioned s akeholde domains (e.g. museums, aqua ia, esea ch cen es, Region o
C e e, Minis y o En i onmen , NGOs, municipali ies, c uise sec o , comme ce, ou
guides, di e s, eache s, ho el owne s) ela ed o he ma ine esea ch a ea o He aklion
2
2Skou adakis G e al
Bay (BBT12). Acco ding o he s akeholde s o He aklion BBT, he coas al
de elopmen
on he no he n sho eline is e y high and, he e o e, is conside ed a p essu e on he
sys em. Con ol o he p essu es and isks s emming om he coas al de elopmen
should be much mo e imp o ed, while he e is a need o s onge go e nance o ensu e
sus ainable de elopmen o he economic sec o s. Mass- ou ism is also s ongly p esen
ac oss he no he n sho e, accompanying o en by nega i e conno a ions.
Me hods
In his s udy, h ee main e en s ha lead o signi ican biodi e si y change a e conside ed
in a bow- ie isk analysis (Fig. 1). These e en s a e:
1. he ba en ocky ee s;
2. he inc ease o non-indigenous species;
3. he dec ease/loss o na i e biodi e si y.
On he le -hand side o he bow- ie analysis, unde causes, lies he lis o ac i i ies
a ec ing he ma ine en i onmen and an h opogenic p essu es h ough which human
ac i i ies a ec he ma ine ecosys em o he BBT. P e en a i e con ols ollow, aiming o
educe he a o emen ioned p essu es. On he igh -hand side o he bow- ie igu e, we
p esen he mi iga ion measu es (con ols) and he consequences o biodi e si y change.
To implemen he ool ac oss Eu opean seas, he s anda dised ocabula y and
classi ica ion o each elemen is applied, ollowing he me hodology desc ibed by Ellio e
al. (2025).
Le e s and numbe s in he ex and Fig. 1 a e decoded as ollowing: C l3.1 - Moni o ing
(o he en i onmen , ac i i ies, impac s on he ecosys em and/o socie y), C l4.1 - EU/
Figu e 1.
He aklion BBT bow- ie isk analysis conce ning biodi e si y change.
Analysis o he causes and consequences o he majo conce n on biodi e si y ... 3
in e na ional legisla ion (en o cemen , new adop ion), C l4.2 - Na ional/local legisla ion
(en o cemen , new adop ion), C l4.1.2 - Adap i e legisla ion which can eac o
unexpec ed posi i e o nega i e changes, allow inno a ion de elopmen , C l5.1.1 -
Go e nmen compensa ion paymen s o, o example, mi iga e he loss o e enues and
C l5.1.2 - Economic incen i es o imp o e/p omo e/suppo al e na i e ac i i ies wi h
lowe impac on biodi e si y (inno a ion).
Resul s
The causes o biodi e si y change in He aklion Bay ha e been iden i ied h ough expe
judgemen and consul a ion wi h s akeholde s including museums, aqua ia, esea ch
cen es, Region o C e e, Minis y o En i onmen , NGOs, municipali ies, c uise sec o ,
comme ce, ou guides, di e s, eache s and ho el owne s. The cen al e en s desc ibed
in he bow- ie analysis (Fig. 1) a e:
• he shi o ba en ocky ee s;
• he con inuous es ablishmen o non-indigenous ma ine species;
• he dec ease/loss o na i e biodi e si y.
Ba en ocky ee s. Inpu o sp ead o non-indigenous species (P1.1) is he main p essu e
d i ing he once mac oalgae-domina ed Medi e anean ocky ee s o he a ea o become
ba en ee s. The wo non-indigenous species o abbi ish Siganus lu idus and Siganus
i ula us which ha e been es ablished in He aklion Bay o decades now and agg ega e
in imp essi e numbe s a e o e g azing he canopy o he ocky ee s o such an ex en
ha only u algae can su i e on hem. Addi ionally, he non-indigenous u chin
Diadema se osum has also es ablished in he a ea in g ea numbe s, u he inc easing
he o e g azing p essu e on he ocky ee s. The la e , ha ing los he in ica e h ee-
dimen ional complexi y ha he mac oalgal canopy p o ides, a e becoming less di e se,
leading o dec ease in p o isioning (C1.2) and egula ing (C1.3) Ecosys em Se ices.
This could u he enhance he isk o e en mo e non-indigenous species es ablishing
and u he al e ing hei biodi e si y. The e is also a dec ease o aes he ic alue/bene i s
(C3.1) associa ed wi h he dominance o ba en ee s. Apa om con inuously moni o ing
(C l3.1) he ecological s a e o he ocky ee habi a , ecosys em es o a ion (C l1.2.1)
can be u ilised o mi iga e his phenomenon.
Non-indigenous species. Excep o he a o emen ioned non-indigenous species, mo e
ha e es ablished in He aklion Bay as a esul o he p essu e ha clima e change (P4)
exe s on he ma ine en i onmen . Some o hem, like Lagocephalus scele a us, ha e
nega i e e ec s as hey in e e e wi h comme cial ac i i ies like ishing. O he s, like
To quigene la imaculosus and Pa upeneus o sskali, a e e y abundan in He aklion
Bay and, by di ec compe i ion, a e con ibu ing o he educ ion o comme cially impo an
na i e species, o example, Mullidae. The esul is, like p e iously, a dec ease in
p o isioning (C1.2) and egula ing (C1.3) Ecosys em Se ices and also a change in he
unde wa e seascape (C1.4) and dec ease in o he cul u al bene i s (C3.4). Once again,
con inuously moni o ing (C l3.1) he ecological s a e o he ma ine en i onmen is
4Skou adakis G e al
essen ial and ecosys em es o a ion (C l1.2.1) can be u ilised o mi iga e his
phenomenon.
Loss o na i e biodi e si y. All o he p essu es shown in he bow- ie analysis (Fig. 1) a e
linked o he dec ease/loss o na i e biodi e si y. Mo e speci ically, human impac s (li e ,
sewage, emissions) (P3.4 and P3.2) and he dis u bance caused by an h opogenic
sound (P3.5) a e he p essu es exe ed by Tou ism and Leisu e (A8) h ough
in as uc u e (A8.1) and ac i i ies (A8.2). Ex ac ion o wild species (P1.6) om he
ma ine en i onmen and he Physical Dis u bance o seabed (P2.1) a e he p essu es
linked o he Ex ac ion o li ing esou ces (A4) and, mo e speci ically, o ish and shell ish
ha es ing (A4.1). Las , bu no leas , he sp ead o non-indigenous species (P1.1) and
clima e change (P4) a e also con ibu ing o loss o na i e biodi e si y. Howe e , hei
causes canno be ound in he s ic con ines o He aklion BBT as hey a e phenomena
conce ning he whole o he Medi e anean and beyond and a e linked o global ade
and decision-making/poli ics. The consequences o he loss o na i e biodi e si y a e
e y se ious since no only do we ha e a dec ease in p o isioning (C1.2) and egula ing
(C1.3) Ecosys em Se ices, bu also di ec economical consequences on g oups like
ishe s by dec easing hei income (C2.2) and ha ing a nega i e impac on he labou
ma ke (C2.4). Mi iga ion measu es o his a e go e nmen compensa ions (C l5.1.1) o
loss o income and economic incen i es o p omo e inno a i e ac i i ies wi h lowe impac
on biodi e si y (C l5.1.2). Once again, con inuously moni o ing (C l3.1) o he ecological
s a e o he ma ine en i onmen is essen ial and ecosys em es o a ion (C l1.2.1) can be
u ilised o mi iga e he loss o na i e biodi e si y.
Conclusions
Clima e change has a g ea e ec on he ma ine en i onmen o he a ea and, since i is a
global phenomenon, i s causes canno be con ined o he s udy a ea. I is unknown i he
es ablishmen o ba en ee s, he inc ease o non-indigenous species and he
opicalisa ion o mos o he eas e n Medi e anean is e e sible, bu con inuous
moni o ing along wi h an e o o mi iga e he e ec s o clima e change a e c i ical. La ge-
scale ou ism has also been iden i ied as an impo an d i e o biodi e si y change in
He aklion BBT, u he enhancing he p essu e on he ma ine en i onmen . The e o e,
moni o ing o mac oben hic communi ies o so -bo om habi a s is c ucial as hey a e
conside ed o be one o he main Biological Quali y Elemen s (BQEs) used unde he
Wa e F amewo k Di ec i e o assess ecological s a us in coas al wa e s, as well as being
sensi i e indica o s o en i onmen al changes and human impac s unde he Ma ine
S a egy F amewo k Di ec i e. Tou is ic de elopmen needs o be egula ed, as
o e exploi a ion o esou ces and he associa ed physical dis u bance a e enhancing he
deg ada ion o he ma ine en i onmen o He aklion Bay.
Analysis o he causes and consequences o he majo conce n on biodi e si y ... 5
Funding p og am
This esea ch is unded by he Eu opean Union Ho izon Eu ope p ojec : MARine
Biodi e si y and Ecosys em Func ioning leading o Ecosys em Se ices (EC HE - P ojec
101060937 — MARBEFES).
Hos ing ins i u ion
Hellenic Cen e o Ma ine Resea ch - Ins i u e o Ma ine Biology, Bio echnology and
Aquacul u e.
Con lic s o in e es
The au ho s ha e decla ed ha no compe ing in e es s exis .
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