![(A) Relationship between asymptotic length (L∞) and growth rate (K) of pumpkinseed Lepomis gibbosus from inland waters of Europe and North America based on the literature [24]. (B) Relationship between estimated asymptotic length (L∞) of Lepomis gibbosus with latitude in European inland water systems [24]. Red circle indicates the estimates from the present study.](https://www.researchgate.net/profile/Alexandra-Douligeri/publication/372852428/figure/fig5/AS:11431281432221930@1746840930483/A-Relationship-between-asymptotic-length-L-and-growth-rate-K-of-pumpkinseed_Q320.jpg)
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Citation: Douligeri, A.S.; Ziou, A.;
Korakis, A.; Kiriazis, N.; Petsis, N.;
Katselis, G.; Moutopoulos, D.K.
Notes on the Summer Life History
Traits of the Non-Native
Pumpkinseed (Lepomis gibbosus)
(Linnaeus, 1758) in a High-Altitude
Artificial Lake. Diversity 2023,15, 910.
https://doi.org/10.3390/
d15080910
Academic Editors: Christos Gkenas,
Nicholas Koutsikos and Leonidas
Vardakas
Received: 3 July 2023
Revised: 30 July 2023
Accepted: 30 July 2023
Published: 2 August 2023
Copyright: © 2023 by the authors.
Licensee MDPI, Basel, Switzerland.
This article is an open access article
distributed under the terms and
conditions of the Creative Commons
Attribution (CC BY) license (https://
creativecommons.org/licenses/by/
4.0/).
diversity
Article
Notes on the Summer Life History Traits of the Non-Native
Pumpkinseed (Lepomis gibbosus) (Linnaeus, 1758) in a
High-Altitude Artificial Lake
Alexandra S. Douligeri 1, Athina Ziou 1, Athanasios Korakis 2, Nikolaos Kiriazis 2, Nikolaos Petsis 2,
George Katselis 1and Dimitrios K. Moutopoulos 1, *
1Department of Fisheries & Aquaculture, University of Patras, 30200 Mesolongi, Greece;
alexandra.douligeri@gmail.com (A.S.D.); athinaziou@gmail.com (A.Z.); gkatselis@upatras.gr (G.K.)
2Management Unit of Northern Pindos National Park, N.E.C.C.A., 44007 Ioannina, Greece;
akorakis@hotmail.com (A.K.)
*Correspondence: dmoutopo@upatras.gr
Abstract:
In the present study, the biology of the pumpkinseed Lepomis gibbosus in the artificial lake
of Aoos, located in northwestern Greece, was investigated. The samplings of the pumpkinseed
were conducted from the shore using a portable electrofishing device over a 4-month period (July
2021–October 2021). A total of 581 specimens were caught, with an average length of 62 mm. The
sex ratio of female to male was estimated to be 1.0:1.7, and the percentage of mature specimens was
estimated for all of the months to be above 52%, matching the highest percentage in July (57.4%).
The b value of the length–weight relationship ranged from 3.16 in September to 3.31 in July. The
value of the L
∞
and K was estimated to be equal to 119 mm and 0.36 years
−1
, respectively, and
the value of
ϕ0
was equal to 3.707. The total mortality was estimated to be equal to 1.63
±
0.48 y
−1
(R
2
= 0.96), and the natural and fishing mortalities were 0.83 and 0.80, respectively. The maximum
age was 6 years, and the theoretical maximum age was 8 years. In the current study, the value of the
L
∞
was estimated to be near the European average but significantly lower than the North American
one, whereas the value of the K was slightly higher than the European average. The small size of the
specimens obtained in Aoos Springs was most likely owed to the combined impact of the investigated
lake’s high altitude and low food availability, resulting in a limited factor for species expansion.
Keywords: growth parameters; condition factor; spatial distribution; Greece
1. Introduction
Non-native species have migrated, survived, and reproduced across a range of habitats
and are putting strain on native fauna. Such species are known to cause adverse envi-
ronmental, economic, and social impacts, such as alterations in the populations of native
species, the transmission of diseases, and significant irreversible changes in the natural
environment [
1
]. Consequently, international agreements, initiatives, regulations, and
conservation strategies have been developed to prevent their spread and timely eradicate
and manage established populations, thereby preserving biodiversity [
2
]. Inland fauna
in Greece displays one of the highest degrees of endemicity in Europe [
3
,
4
]. However,
these populations are under severe pressure due to reduced rainfall and an increase in
water temperature pollution and human activities, which are further enhanced by the
introduction and spread of non-native species [5–7].
The high-altitude artificial lake of Aoos has evolved into an important mountainous
aquatic ecosystem with an abundance of native aquatic organisms. In contrast, certain
non-native fish species have been introduced into the system, including the pumpkinseed
Lepomis gibbosus (Linnaeus, 1758) and Prussian carp Carassius gibelio (Bloch, 1782), which
are considered among the most threatening species for global biodiversity [
8
] but also
Diversity 2023,15, 910. https://doi.org/10.3390/d15080910 https://www.mdpi.com/journal/diversity
Diversity 2023,15, 910 2 of 15
for the lake’s aquatic fauna. Pumpkinseed is considered a non-native species capable of
causing disturbances within the habitat and fish fauna of inland waters that have been
introduced [9].
The first introduction of the pumpkinseed to Europe, and specifically to France, is
believed to have occurred in 1877 [
10
] through river channels. The purpose and history
of the species introduction into the inland waters of European countries are somewhat
unclear. As the pumpkinseed can be seen as an ornamental species, it was introduced
and stocked in small garden ponds and aquariums, from which it was either deliberately
released or accidentally escaped into inland waters, which played a key role in the spread
of the species [
11
]. Another reason is its use as bait by recreational fishers [
12
]. The
pumpkinseed was first reported in Greece in 1885 [
13
], and the first settled population was
recorded approximately 100 years later in the Aliakmonas River in Macedonia (Northwest
Greece) [
14
]. It was recently introduced into the artificial lake of Aoos during the middle of
the preceding decade [15].
Pumpkinseed prefers shallow waters, with little water movement and enough vegeta-
tion, and the temperature it lives in ranges from 4
◦
C to 30
◦
C [
16
]. It thrives and reproduces
in a variety of habitats [
17
], and its presence may have a major impact on the richness of the
ecosystems in which it settles [
18
]. The breeding season of pumpkinseed begins when the
water temperature rises, usually around 20
◦
C, although the duration and specific timing
may vary depending on the region [
19
]. Males are capable of breeding with several females
in succession. After spawning, the male guards the eggs in a nest and subsequently protects
juveniles until they absorb their yolk sac [
20
]. The species typically reaches sexual maturity
at around 1–2 years of age [
20
]. With respect to feeding habits, the pumpkinseed primarily
feeds on worms, crustaceans, and insects. Additionally, it consumes small fish, fish eggs,
and other vertebrates [
21
]. Distinct differences exist between North American populations,
where the pumpkinseed is native, and European populations [22]. In Europe, the average
length and growth rate of adult pumpkinseeds tend to be smaller compared to those in
America. Moreover, the average asymptotic length (L
∞
) is higher in American populations
than in European ones. Up to this point, the pumpkinseed has been documented in 32 lentic
ecosystems across Greece [
23
]. However, information regarding its biology is limited to a
survey conducted in the artificial lake of Kerkini two decades ago [
12
] and, more recently, a
study investigating its abundance in Lake Volvi over a three-year period [9].
The purpose of this study is to investigate the biology of the pumpkinseed in the
artificial lake of Aoos by assessing its biometric characteristics, robustness, and life history
parameters, including age estimation, asymptotic length, and mortality. Sampling was
employed during the breeding season and within the breeding habitats of the species
because the sampling design was set to manage the population of the species by selectively
removing sexually mature specimens found in the nests [
24
]. In the context of an ecosystem-
based approach, the findings of the present study were compared with those of the North
American, where the species is native, and European populations, where the species is non-
native, in order to investigate the area’s effect (the latitude and altitude) on the life history
traits of the studied species. This conjunctive analysis holds particular significance due to
the fact that the studied lake is a high-altitude alpine-type lake (1343 m) characterized by
strong temperature fluctuations [
25
] that impact the survival of the organisms within it. The
findings from this research will contribute to the effective management of the pumpkinseed
population in the studied system.
2. Materials and Methods
2.1. Study Area Sampling
The artificial lake of Aoos is an “alpine-type” ecosystem located at an altitude of
1343 m
within the mountainous area of Northern Pindos (Figure 1). It covers an area of
11.5 km2
and has a capacity of 260
×
10
6
m
3
, with a maximum depth reaching 80 m. The
system is oligotrophic, characterized by an annual temperature fluctuation ranging from
4◦C
to
26 ◦C
, while the surface level undergoes an approximate 10 m variation per year [
25
].
Diversity 2023,15, 910 3 of 15
The system is monomictic when there is no ice formation, changing to dimictic when ice is
formed [
26
]. The water column is thermally structured during summer, whereas it appears
to be quite uniform from the surface to the bottom throughout the rest of the year [
25
].
Water temperature annually ranges from 4 to 6
◦
C in March to 5 to 21
◦
C in July, with the
formation of thermal layers occurring at depths of 5–15 m during the summer season [
25
].
Mountain springs and river runoff discharged from adjacent mountains are limited, and
the system assembles the characteristics of a natural lake [
26
]. The fish fauna of the arti-
ficial lake of Aoos consists of both native species, such as
Salmo farioides
, Karaman 1938,
Barbus prespensis
, Karaman 1924, Squalius sp. Aoos (‘unnamed and undescribed taxa’, ac-
cording to [
27
]), and Alburnoides bipunctatus, Bloch 1782, as well as introduced species, such
as Oncorhynchus mykiss, Walbaum 1792,
Cyprinus carpio
, Linnaeus 1758,
Carassius gibelio
,
Bloch 1782, and Acipenser gueldenstaedtii Brandt and Ratzeburg 1833, which are confirmed
by recreational fishers [28].
Diversity2023,15,xFORPEERREVIEW3of16
2.MaterialsandMethods
2.1.StudyAreaSampling
TheartificiallakeofAoosisan“alpine‐type”ecosystemlocatedatanaltitudeof1343
mwithinthemountainousareaofNorthernPindos(Figure1).Itcoversanareaof11.5
km2andhasacapacityof260×106m3,withamaximumdepthreaching80m.Thesystem
isoligotrophic,characterizedbyanannualtemperaturefluctuationrangingfrom4°Cto
26°C,whilethesurfacelevelundergoesanapproximate10mvariationperyear[25].The
systemismonomicticwhenthereisnoiceformation,changingtodimicticwheniceis
formed[26].Thewatercolumnisthermallystructuredduringsummer,whereasitap‐
pearstobequiteuniformfromthesurfacetothebottomthroughouttherestoftheyear
[25].Watertemperatureannuallyrangesfrom4to6°CinMarchto5to21°CinJuly,with
theformationofthermallayersoccurringatdepthsof5–15mduringthesummerseason
[25].Mountainspringsandriverrunoffdischargedfromadjacentmountainsarelimited,
andthesystemassemblesthecharacteristicsofanaturallake[26].Thefishfaunaofthe
artificiallakeofAoosconsistsofbothnativespecies,suchasSalmofarioides,Karaman1938,
Barbusprespensis,Karaman1924,Squaliussp.Aoos(‘unnamedandundescribedtaxa’,ac‐
cordingto[27]),andAlburnoidesbipunctatus,Bloch1782,aswellasintroducedspecies,
suchasOncorhynchusmykiss,Walbaum1792,Cyprinuscarpio,Linnaeus1758,Carassius
gibelio,Bloch1782,andAcipensergueldenstaedtiiBrandtandRatzeburg1833,whichare
confirmedbyrecreationalfishers[28].
Experimentalelectrofishingfromthecoastwasappliedaroundthelakeduringthe
morninghourswithafrequencyofapproximatelyeverytendaysoverafour‐monthpe‐
riod(July2021–October2021).ThedeviceusedwasaHans‐GrasslGmbHbattery‐pow‐
eredbackpack,ModelIG200‐2,DC(pulsed),1.5KWoutputpower,35–100Hz,max.850
V(Schönau,Germany).Electrofishingwasappliedatfourstations(A,B,C,andD)inthe
southernpartofthelakeinthecreekswithshallowwatersandbasedonthepresenceof
nestsatthesepoints(Figure1).Inparticular,stationsCandDareplaceswherenestingof
thespecieswasrecorded,whileinstationsAandB,whichhavesimilarcharacteristicsof
thesubstrate(modifiedcoastlinewithrip‐rap),nestingwasnotrecorded.
Figure1.SamplingsitesintheartificiallakeofAoos.
Figure 1. Sampling sites in the artificial lake of Aoos.
Experimental electrofishing from the coast was applied around the lake during the
morning hours with a frequency of approximately every ten days over a four-month period
(July 2021–October 2021). The device used was a Hans-Grassl GmbH battery-powered
backpack, Model IG200-2, DC (pulsed), 1.5 KW output power, 35–100 Hz, max. 850 V
(Schönau, Germany). Electrofishing was applied at four stations (A, B, C, and D) in the
southern part of the lake in the creeks with shallow waters and based on the presence of
nests at these points (Figure 1). In particular, stations C and D are places where nesting of
the species was recorded, while in stations A and B, which have similar characteristics of
the substrate (modified coastline with rip-rap), nesting was not recorded.
2.2. Data Collection
The specimens were preserved in formalin and transported to a laboratory where each
specimen was measured for the total and standard length with a precision of 0.1 cm. The
gross weight was also recorded, and the liver and gonads were removed and weighed. In
the case of mature specimens, their sex was also identified. All weight measurements were
taken using a balance with an accuracy of 0.01 g. Total length data were used to separate
length classes every 5 mm for the entire sample period, and then we estimated the length–
weight relationship in the total sample monthly and by sex by applying the following
equation: W = a TL
b
, where W is the gross weight, TL is the total length, and coefficients
Diversity 2023,15, 910 4 of 15
a and b are the intercept of the curve on the weight axis and the slope of the equation,
respectively. Coefficient b usually takes values from 2 to 4, both inter- and intra-specifically,
when there are records from different regions, seasons, and years [
29
]. Prior to the use of
a statistical test, the distributions of the length data per sex and season were examined
for whether or not they deviated significantly from the normal distribution by using the
Shapiro–Wilk test [
30
]. The comparison of the mean total length between the months
was performed with co-variance analysis (ANOVA, p< 0.05), whereas the comparison
of the sex with the seasons (Summer–Autumn) was performed with a Student’s t-test
(p< 0.05). The comparison of the respective distributions between the two different seasons
was performed with Kolmogorov–Smirnov analysis (K-S test) [
30
]. The comparison of the
length–weight relationship with months was performed using an analysis of co-variance
(ANCOVA, MS Office Excel 2019).
To determine the breeding season of the species, the gonads of sexually mature
specimens were removed and weighed. The gonadosomatic index was then estimated
using the equation [
31
]: GSI = (GW/W)
×
100, where GW is the weight of the gonad
measured in gr, and W is the total weight of the fish. The index was estimated separately
for each sex and month to identify the main breeding season of the species. Additionally,
the sex ratio was estimated to provide information on the prevalence of each sex, the season,
and sampling location.
The length data were utilized to calculate the growth rate (K) and asymptotic length
(L
∞
) using the ELEFAN I method [
32
] from FISAT II software [
33
]. The smallest length
class was set to 20 mm, and the class intervals were set to 5 mm. To determine the best fit,
the fit index, Rn [
32
], was applied to the length–frequency data set. Age, t
0
, was estimated
using Pauly’s equation [
34
]: Log(
−
t
0
) =
−
0.3922
−
0.2752 * LogL
∞−
1.038 * LogK, where
L
∞
and K represent the growth parameters estimated before. The growth efficiency index
was calculated using the equation [35]: ϕ0= LogK + 2 * LogL∞.
Parameters L
∞
and K were used to estimate the total mortality (Z) by employing
the length-converted catch curve in the FISAT II software [
33
]. Natural mortality (M)
was estimated using parameters L
∞
and K, according to the empirical equation of [
32
]:
Log(M) =
−
0.0066
−
0.2790 * Log(L
∞
) + 0.6543 * Log(K) + 0.4634 * Log(T), where T is the
average annual temperature of the lake, which, in the present study, was T = 13
◦
C [
26
].
Fishing mortality (F) was estimated as the difference between total mortality (Z) and natural
mortality (M), F = Z −M.
To determine the age of the fish, scales were carefully removed from the bottom of the
pectoral fins and photographed using an electron microscope with a resolution of 500
×
.
Subsequently, a photo editor was employed to measure the radius and distances between
rings to confirm that they were annual. The length classes were then grouped by age, and
the total length-at-age keys were constructed using 5 mm length intervals. Specimens at
age 0 were identified as those that had not yet completed the formation of the first ring. To
estimate the maximum age (t
max
) of the species in the lake, von Bertalanffy’s equation [
36
]
was used: Lmax = L∞* (1 −e(−K(tmax −t0))), where Lmax = 0.95 * L∞.
A literature review has also been conducted on growth studies of pumpkinseed found
in North America, where the species is native, and Europe, where the species is non-native,
and specifically, the relationships among the life history traits, as well as between these
traits and the age–class identified in the above-mentioned areas, and with the area’s effect
(latitude, altitude).
3. Results
3.1. Estimation of Life History Traits
The length and weight were measured for a total of 581 specimens of pumpkinseed,
where 364 specimens were collected during the summer (July–August 2021), and 217 were
collected during the autumn (September–October 2021) samplings. The highest number of
specimens (310) was collected in August, while the lowest number (54) was collected in
July (Table 1). The length ranged from 24 mm to 101 mm, with the mean length of all the
Diversity 2023,15, 910 5 of 15
specimens estimated to be 62 mm (SD: 13 mm). In the summer, the mean length was 64 mm
(SD: 13 mm), while in the autumn, it was 58 mm (SD: 15 mm). The Shapiro–Wilk test for the
length data by season and sex showed that their distribution did not deviate significantly
(p< 0.05) from the normal distribution. The comparison of the length frequency distribu-
tions between seasons exhibited no significant (K–S = 0.71, p> 0.05) differences. A total of
108 females and 193 males were identified, while 280 specimens did not have detectable
gonads, either due to the release of reproductive material or because they had not yet
reached the age of first maturity. The mean length of the males (mean: 70 mm, SD: 10 mm)
was significantly (Student’s t-test, p< 0.05) longer than that of the females (mean: 67 mm,
SD: 8 mm). The specimens whose sex was not identified had a significantly (Student’s t-test,
p< 0.05) shorter mean length (mean value: 54 mm, SD: 11 mm) compared to both sexes.
In terms of size classes, most of the males were found in the 60–80 mm range, while the
females were predominantly in the 50–70 mm range (Figure 2).
Table 1.
Descriptive statistics and parameters of total length and length–weight relationship,
W = aTL
b
[weight (in g) and length (in cm)] of pumpkinseed Lepomis gibbosus by month, season,
and for all months for the samples caught in the artificial lake of Aoos in 2021. R
2
is the coefficient
of determination.
Month/Season NTL W = aTLb
Min Max Mean SD a-Value b-Value R2
Month
July 54 42 90 63 11.9 0.009 3.306 0.990
August 310 44 101 64 13 0.011 3.212 0.983
September
160 30 95 63 15 0.013 3.156 0.982
October 57 24 71 44 14.8 0.012 3.174 0.994
Season
Summer 364 42 101 64 13 0.011 3.233 0.984
Autumn 217 24 95 58 15 0.012 3.194 0.986
TOTAL 581 24 101 62 13 0.012 3.192 0.985
Diversity2023,15,xFORPEERREVIEW5of16
betweenthesetraitsandtheage–classidentifiedintheabove‐mentionedareas,andwith
thearea’seffect(latitude,altitude).
3.Results
3.1.EstimationofLifeHistoryTraits
Thelengthandweightweremeasuredforatotalof581specimensofpumpkinseed,
where364specimenswerecollectedduringthesummer(July–August2021),and217were
collectedduringtheautumn(September–October2021)samplings.Thehighestnumber
ofspecimens(310)wascollectedinAugust,whilethelowestnumber(54)wascollected
inJuly(Table1).Thelengthrangedfrom24mmto101mm,withthemeanlengthofall
thespecimensestimatedtobe62mm(SD:13mm).Inthesummer,themeanlengthwas
64mm(SD:13mm),whileintheautumn,itwas58mm(SD:15mm).TheShapiro–Wilk
testforthelengthdatabyseasonandsexshowedthattheirdistributiondidnotdeviate
significantly(p<0.05)fromthenormaldistribution.Thecomparisonofthelengthfre‐
quencydistributionsbetweenseasonsexhibitednosignificant(K–S=0.71,p>0.05)differ‐
ences.Atotalof108femalesand193maleswereidentified,while280specimensdidnot
havedetectablegonads,eitherduetothereleaseofreproductivematerialorbecausethey
hadnotyetreachedtheageoffirstmaturity.Themeanlengthofthemales(mean:70mm,
SD:10mm)wassignificantly(Student’st‐test,p<0.05)longerthanthatofthefemales
(mean:67mm,SD:8mm).Thespecimenswhosesexwasnotidentifiedhadasignificantly
(Student’st‐test,p<0.05)shortermeanlength(meanvalue:54mm,SD:11mm)compared
tobothsexes.Intermsofsizeclasses,mostofthemaleswerefoundinthe60–80mm
range,whilethefemaleswerepredominantlyinthe50–70mmrange(Figure2).
Figure2.LengthclasspersexofpumpkinseedLepomisgibbosusspecimenscaughtfromJuly2021to
October2021.
Theestimationofthelength–weightrelationship,conductedfortheentiresampling
periodonaseasonalandmonthlybasis,revealedthatinallofthecases,theweightexhib‐
itedasignificant(allR
2
valuesweregreaterthan0.982)positiveallometricrelationship
withthelength,withslopeb(3.15)beingsignificantly(Student’st‐test,p<0.05)higher
thantheisometricgrowth(Table1).Themonthlyvariabilityofslopebrangedfrom3.156
inSeptemberto3.306inJuly,whileparameterarangedfrom0.009inJulyto0.013inSep‐
tember(Table1).Whencomparingthelength–weightrelationshipbetweenthesexes,
therewasnosignificant(ANCOVA,p>0.05)differenceobservedforaandb.However,
whencomparingparametersaandbbymonth,significant(ANCOVA,p<0.05)
Figure 2. Length class per sex of pumpkinseed Lepomis gibbosus specimens caught from July 2021 to
October 2021.
The estimation of the length–weight relationship, conducted for the entire sampling
period on a seasonal and monthly basis, revealed that in all of the cases, the weight exhibited
a significant (all R
2
values were greater than 0.982) positive allometric relationship with
the length, with slope b (3.15) being significantly (Student’s t-test, p< 0.05) higher than
the isometric growth (Table 1). The monthly variability of slope b ranged from 3.156 in
September to 3.306 in July, while parameter a ranged from 0.009 in July to 0.013 in September
Diversity 2023,15, 910 6 of 15
(Table 1). When comparing the length–weight relationship between the sexes, there was no
significant (ANCOVA, p> 0.05) difference observed for a and b. However, when comparing
parameters a and b by month, significant (ANCOVA, p< 0.05) differences were found for
each pair of months, except for parameter a in July, which did not significantly (ANCOVA,
p> 0.05) differ from the other three months.
The sex ratio was 1.0:1.7, female to male. The mature and immature specimens were
almost equal throughout the entire sampling period, with the exception of October, when
the majority (78.9%) were immature. The highest proportion of reproductive maturity was
observed in July, with a percentage of 57.4%.
The females exhibited significantly (ANOVA test; p< 0.05) higher values of the go-
nadosomatic index compared to the males (Figure 3A). Among the sexes, the highest
gonadosomatic index value was estimated in July, reaching 4.67 for the females and 1.41
for the males. Conversely, the lowest values were recorded in September (0.49 and 0.34,
respectively). In October, there was a slight increase in the gonadosomatic index for both of
the sexes, with an increment of 0.05 for the males and 0.11 for the females. Analyzing the
monthly fluctuations of the condition factors in relation to the gonadosomatic index, the
condition factors reached their maximum values when the gonadosomatic index exhibited
its minimum value (Figure 3B). Specifically, the gonadosomatic index exhibited its highest
value in July, while condition factors were at their lowest. In contrast, during September,
all of the condition factors marked an increase, while the gonadosomatic index reached its
minimum value.
Diversity2023,15,xFORPEERREVIEW6of16
differenceswerefoundforeachpairofmonths,exceptforparameterainJuly,whichdid
notsignificantly(ANCOVA,p>0.05)differfromtheotherthreemonths.
Thesexratiowas1.0:1.7,femaletomale.Thematureandimmaturespecimenswere
almostequalthroughouttheentiresamplingperiod,withtheexceptionofOctober,when
themajority(78.9%)wereimmature.Thehighestproportionofreproductivematuritywas
observedinJuly,withapercentageof57.4%.
Thefemalesexhibitedsignificantly(ANOVAtest;p<0.05)highervaluesofthego‐
nadosomaticindexcomparedtothemales(Figure3A).Amongthesexes,thehighestgo‐
nadosomaticindexvaluewasestimatedinJuly,reaching4.67forthefemalesand1.41for
themales.Conversely,thelowestvalueswererecordedinSeptember(0.49and0.34,re‐
spectively).InOctober,therewasaslightincreaseinthegonadosomaticindexforbothof
thesexes,withanincrementof0.05forthemalesand0.11forthefemales.Analyzingthe
monthlyfluctuationsoftheconditionfactorsinrelationtothegonadosomaticindex,the
conditionfactorsreachedtheirmaximumvalueswhenthegonadosomaticindexexhibited
itsminimumvalue(Figure3B).Specifically,thegonadosomaticindexexhibiteditshighest
valueinJuly,whileconditionfactorswereattheirlowest.Incontrast,duringSeptember,
alloftheconditionfactorsmarkedanincrease,whilethegonadosomaticindexreached
itsminimumvalue.
Table1.Descriptivestatisticsandparametersoftotallengthandlength–weightrelationship,W=
aTL
b
[weight(ing)andlength(incm)]ofpumpkinseedLepomisgibbosusbymonth,season,andfor
allmonthsforthesamplescaughtintheartificiallakeofAoosin2021.R
2
isthecoefficientofdeter‐
mination.
Month/SeasonΝ TLW=aTL
b
MinMaxMeanSDa‐Valueb‐ValueR
2
Month
J
uly5442906311.90.0093.3060.990
August3104410164130.0113.2120.983
September160309563150.0133.1560.982
October5724714414.80.0123.1740.994
Season
Summer 3644210164130.0113.2330.984
Autumn217249558150.0123.1940.986
TOTAL5812410162130.0123.1920.985
Figure3.(A)Monthlyvariationofthegonadosomaticindex(GSI)bysex.(B)Monthlyvariationof
thefourconditionfactorsstudied(Fulton,LeCren,Allometric,HIS)inrelationtothevariationof
thegonadosomaticindex(GSI)forpumpkinseedintheartificiallakeofAoos.
ThevaluesoftheL∞andKwereanestimated119mmand0.36years
−1
,respectively.
Theindex,Rn,was0.691.Thevalueoft
0
wasanestimated−0.31years.Thegrowtheffi‐
ciencyindex,φ′,wasestimatedtobeequalto3.707.Totalmortality,Z,wasestimatedto
beequalto1.63±0.48y
−1
(r
2
=
0.956),witha95%confidenceintervalbetween1.15and2.12
y
−1
.Thenaturalmortality,M,wasestimatedtobeequalto0.829forameanannualwater
Figure 3.
(
A
) Monthly variation of the gonadosomatic index (GSI) by sex. (
B
) Monthly variation of
the four condition factors studied (Fulton, Le Cren, Allometric, HIS) in relation to the variation of the
gonadosomatic index (GSI) for pumpkinseed in the artificial lake of Aoos.
The values of the L
∞
and K were an estimated 119 mm and 0.36 years
−1
, respectively.
The index, Rn, was 0.691. The value of t
0
was an estimated
−
0.31 years. The growth
efficiency index,
ϕ0
, was estimated to be equal to 3.707. Total mortality, Z, was estimated to
be equal to 1.63
±
0.48 y
−1
(r
2
= 0.956), with a 95% confidence interval between 1.15 and
2.12 y
−1
. The natural mortality, M, was estimated to be equal to 0.829 for a mean annual
water temperature of 13
◦
C. The fishing mortality, F, and the exploitation rate, E, were
estimated to be 0.80 and 0.49, respectively.
Length classes were constructed in 5 mm increments, ranging from a minimum length
of 20–25 mm to a maximum length of 100–105 mm, covering an age range of 0 to 6 years
(Table 2). The largest percentage of specimens was observed between 55 mm (19.8%)
and 60 mm (17.4%), which were between 0 and 2 years old. At age 0+, there is a wide
range of lengths, starting from 20 mm and extending up to 65 mm. At 50 mm, there is an
overlap with the specimens aged 1-year-old. The third largest percentage of specimens
(14.6%) was found at 70 mm, representing the age range of 1 to 3 years. The majority of
the specimens collected were 1 year old (35.3%), followed by 0 (25.3%) and 2 (23.9%) years.
Older specimens accounted for less than 9% of the total. Additionally, only one specimen
of 6 years was found, measuring over 100 mm in length.
Diversity 2023,15, 910 7 of 15
Table 2. Length by age relationship of pumpkinseed in the artificial lake of Aoos.
Length Classes (mm) 0123456
Total %
Age
20–25 1 1 0.2
25–30 5 5 0.9
30–35 17 17 2.9
35–40 16 16 2.8
40–45 16 16 2.8
45–50 17 17 2.9
50–55 37 15 52 9.0
55–60 26 87 2 115 19.8
60–65 9 81 11 101 17.4
65–70 3 18 45 3 69 11.9
70–75 4 60 21 85 14.6
75–80 19 13 4 36 6.2
80–85 2 10 12 1 25 4.3
85–90 3 9 3 15 2.6
90–95 3 3 6 1.0
95–100 4 4 0.7
100–105 1 1 0.2
Total 147 205 139 50 28 11 1 581
% 25.3 35.3 23.9 8.6 4.8 1.9 0.2
The mean length by the age curve for the pumpkinseed reveals a noticeable increase
in the mean length per age, ranging from 47 mm in the 0-year-olds to 90 mm in the 5-year-
olds. Additionally, there was a specimen measuring 101 mm in length, identified as age 6
(Table 2). The maximum age (t
max
) of the pumpkinseed in the artificial lake of Aoos was
estimated equal to 8 years.
3.2. Metanalytic Approach of Life History Traits
According to the results of the current study, the estimated value of parameter b in the
length–weight relationship (3.190) was the second highest compared to the corresponding
estimates from other European freshwater systems, where the species has been introduced,
indicating a relatively good condition in our study area. Specifically, the b parameter
varied from 2.980 in the Segura River, Spain [
37
], to 3.491 in a river basin in Turkey [
38
]
(Appendix A, Table A1).
Regarding the comparisons of life history parameter estimates, the value of the L
∞
in the present study lies within the European mean (120.7 mm) (Appendix A, Table A2),
but it is lower than the average value estimated in North American freshwater systems
(
188.4 mm
), where the species is native. Specifically, in European inland waters [
22
], the
values of the L
∞
range from 81.3 mm in the Tapada Pequena reservoir in Portugal to
168.3 mm
in a section of the Danube River in Slovakia. In North America, the values of
the L
∞
range from 125.3 mm in Lower Beverly Lake, Canada, to 292.5 mm estimated in
various systems studied in the Minnesota region, USA [
22
]. In Greece, only one survey of
the species biology has been conducted in the artificial lake Kerkini, with the L
∞
value
(
136.5 mm
) being the second highest in Europe. The value of parameter K was estimated
in our area to be
0.36 yr−1
, slightly higher than the mean value estimated in European
freshwater systems (
0.33 yr−1
). In the artificial lake Kerkini, the value of K is 0.13 yr
−1
,
while in North America, the K ranges from 0.13 yr
−1
in Upper Beverly Lake, Canada, to
0.63 yr−1in surveys conducted in various water bodies in Delaware, USA.
In the present study, a total of seven age classes were identified, which is estimated
to be the predominant age distribution for pumpkinseed in European freshwater systems
(Figure 4). However, there were a few exceptions. The Tapada Grande reservoir in Portugal,
as well as the Dabas and Cottesmore waterholes in Hungary and England, respectively,
Diversity 2023,15, 910 8 of 15
exhibit five age classes. At the Tapada Pequena reservoir in Portugal, a section of the
Danube River in Slovakia, and the artificial lake Kerkini in Greece, six age classes were
determined. The Divor reservoir in Portugal had the highest number of age classes, reaching
up to eight age classes. In North America, where the species is native, in certain systems,
the number of estimated age classes exceeded seven and reached up to ten [22].
Diversity2023,15,xFORPEERREVIEW9of16
pumpkinseeddepictedasignificant(p<0.05)positivelinearregressionwithhighL∞val‐
uesestimatedathigherlatitudes(Figure5B).
Figure4.RelationshipofthemeanstandardlengthbyageclassofpumpkinseedLepomisgibbosusin
differentfreshwatersystems:(A)inEurope,(B)inNorthAmerica,and(C)inCanada.R:Reservoir,
A.L:ArtificialLake,L:Lake,C:Canal,M:Marsh,P:Pond,Riv:River,W.B:WaterBodies.
Table3.Gonadosomalindex(GSI)andLeCrenconditionfactor(K
R
)valuesofpumpkinseedLepo‐
misgibbosusinEuropeanfreshwatersystems.
RegionCountryMonthGSIΚ
R
YearReference
ArtificiallakeofAoosGreece
J
uly4.671.082021Presentstudy
19waterbodiesEnglandJune7.701.022003–04[40]
LakeEinedammenNorwayJuly7.220.912006[39]
Figure 4.
Relationship of the mean standard length by age class of pumpkinseed Lepomis gibbosus in
different freshwater systems: (
A
) in Europe, (
B
) in North America, and (
C
) in Canada. R: Reservoir,
A.L: Artificial Lake, L: Lake, C: Canal, M: Marsh, P: Pond, Riv: River, W.B: Water Bodies.
To compare the length–age relationships across the various studied ecosystems, the
standard length of the specimens was utilized. The mean length for each age class in the
Diversity 2023,15, 910 9 of 15
present study was estimated to be among the smallest for European freshwater systems
(Figure 4A) and smaller than the mean length estimated in populations studied in the
United States (Figure 4B) and Canada (Figure 4C). The specimens in the first age class in
our study area exhibited an average standard length of 39 mm, whereas the corresponding
average length for the same age group in North America (USA and Canada) was estimated
to be 35 mm. The differences in the average standard lengths were more pronounced in the
subsequent age groups, with the mean lengths in North America being greater.
The Le Cren condition factor estimated for L. gibbosus in European freshwater systems
ranges from 0.88 in Lake Cottesmore School, England [
39
] to 1.19 in Lake Grand-Lieu,
France [
39
] (Table 3). The robustness value estimated in the present study exhibited the
second highest value compared to those estimated from other European freshwater systems
(Table 3). In contrast, the gonadosomatic index value was lower than the mean value
estimated in other European freshwaters [
39
,
40
]. Specifically, the gonadosomatic index
values in other systems range from 3.14 in samples collected in June from the Slangebeek
stream, Belgium, to 11.36 in samples collected in May from Lake Grand-Lieu, France
(Table 3).
Table 3.
Gonadosomal index (GSI) and Le Cren condition factor (K
R
) values of pumpkinseed
Lepomis gibbosus in European freshwater systems.
Region Country Month GSI KRYear Reference
Artificial lake of Aoos Greece July 4.67 1.08 2021 Present study
19 water bodies England June 7.70 1.02 2003–04 [40]
Lake Einedammen Norway July 7.22 0.91 2006 [39]
Lake Schoapedobbe Netherlands June 10.04 1.00 2006 [39]
Lake Meeuwven Netherlands June 8.78 0.91 2006 [39]
Lake Cottesmore School England June 9.80 0.88 2006 [39]
Stream Batts Bridge England June 4.13 0.97 2006 [39]
Isle of Wight England June 6.71 1.07 2005 [39]
Lake Webbekomsbroek Belgium June 6.10 1.04 2006 [39]
Stream Slangebeek Belgium June 3.14 1.05 2006 [39]
Marsh Brière France May 11.20 1.04 2006 [39]
Lake Grand-Lieu France May 11.36 1.19 2006 [39]
The theoretical maximum value of the t
max
for pumpkinseed in our study area was
estimated to equal 8 years, which is lower than the mean value estimated in other Euro-
pean freshwater systems (t
max
= 10 years: Table A2), as well as in North American lakes
(
tmax = 16 years
: Table A2). In the majority of North American freshwater systems, the
t
max
was estimated to be higher than the mean value estimated in European populations.
This highlights the fact that although the species is non-native to these ecosystems, it
seems to have adapted to a satisfactory extent in European ones. Additionally, the rela-
tively earlier maximum age observed in pumpkinseed populations in the artificial lake
of Aoos compared to other systems is likely attributed to the wide temperature ranges
and low nutritional environment that the species encounters in an alpine, high-altitude
lake ecosystem.
The relationship between the L
∞
and K of pumpkinseed from the inland waters of
Europe and North America based on the literature [
22
] depicted a significant (p< 0.05)
negative linear regression with the smallest values of the L
∞
and the highest ones of the K
estimated from the present study (Figure 5A). The relationship between the L
∞
and the
latitude of each system found with the corresponding estimates of the life history traits
of pumpkinseed depicted a significant (p< 0.05) positive linear regression with high L
∞
values estimated at higher latitudes (Figure 5B).
Diversity 2023,15, 910 10 of 15
Diversity2023,15,xFORPEERREVIEW10of16
LakeSchoapedobbeNetherlandsJune10.041.002006[39]
LakeMeeuwvenNetherlands
J
une8.780.912006[39]
LakeCottesmoreSchoolEngland
J
une9.800.882006[39]
StreamBattsBridgeEnglandJune4.130.972006[39]
IsleofWightEngland
J
une6.711.072005[39]
LakeWebbekomsbroekBelgium
J
une6.101.042006[39]
StreamSlangebeek BelgiumJune3.141.052006[39]
MarshBrièreFranceMay 11.201.042006[39]
LakeGrand‐Lieu FranceMay11.361.192006[39]
Figure5.(A)Relationshipbetweenasymptoticlength(L∞)andgrowthrate(K)ofpumpkinseed
LepomisgibbosusfrominlandwatersofEuropeandNorthAmericabasedontheliterature[24].(B)
Relationshipbetweenestimatedasymptoticlength(L∞)ofLepomisgibbosuswithlatitudeinEuro‐
peaninlandwatersystems[24].Redcircleindicatestheestimatesfromthepresentstudy.
4.Discussion
Thepresentstudyaimedtoinvestigatethebiologyofpumpkinseedwithinahigh‐
altitudeartificiallake.Theanalysisofthedatacouldbevaluableforthemanagementof
thespeciespopulationintheartificiallakeofAoos,consideringitsnon‐nativenatureand
impactonthelake’shabitatandfishfauna[15].Thefindingsofthisstudyalsoprovide
importantinsightsandserveasavaluableupdatetotheinitialstudyconductedinGreek
inlandwaters20yearsago[12].
Theobservednumericalpredominanceofmalesoverfemales(1.7:1.0)wasantici‐
patedduetothespecificsamplingmethodemployedduringthebreedingseasonand
withinthebreedingfieldsofthespecies[24].Duringthisperiod,malesconstructnests
andassumetheresponsibilityofguardingandprotectingthefertilizedeggs,whichoften
leadstotheexclusionoffemalesfromthenestingarea[41].Theanalysisofconditionfac‐
tors,aswellastheestimationofthegonadosomaticindex,revealedadistinctpatternfor
ourstudyarea.Itwasobservedthatthepumpkinseeddisplayeditshighestrobustnessin
September,whereasitwaslowestduringsummer.Despitethelackofsamplesduring
spring,whenthespeciesalsoreproduce,thehighestvaluesofthegonadosomaticindex
observedinbothmaleandfemalesduringJulyissupportedbyotherstudies[12,42,43].
Furthermore,italignswiththeperiodwhenthesystemreachesthehighestwatertemper‐
ature(21°C)[26],whichpromotestheinitiationofspeciesreproduction[44].Thedeposi‐
tionofreproductivematerialduringthesummerisfurthersupportedbythefactthatover
52.0%ofthespecimensweresexuallymatureinallofthemonthsexceptforOctoberwhen
themajoritywereimmature(78.9%).
Theaboveobservationsarefurthersupportedbycomparingtherobustnessindices
withthegonadosomaticindex(Figure3B).Themonthlyvariationoftherobustnessindi‐
cesexhibitedaninversepatterncomparedtothegonadosomaticindex.Specifically,the
gonadosomaticindexreacheditsmaximumvalueinJuly,whiletheconditionfactorsex‐
hibitedtheirlowestvaluesduringthismonth.Thiscanbeattributedtothefactthatduring
thereproductiveperiodinsummer,freshwaterfishallocateasignificantamountof
Figure 5.
(
A
) Relationship between asymptotic length (L
∞
) and growth rate (K) of pumpkinseed
Lepomis gibbosus from inland waters of Europe and North America based on the literature [
24
].
(
B
) Relationship between estimated asymptotic length (L
∞
) of Lepomis gibbosus with latitude in
European inland water systems [24]. Red circle indicates the estimates from the present study.
4. Discussion
The present study aimed to investigate the biology of pumpkinseed within a high-
altitude artificial lake. The analysis of the data could be valuable for the management of
the species population in the artificial lake of Aoos, considering its non-native nature and
impact on the lake’s habitat and fish fauna [
15
]. The findings of this study also provide
important insights and serve as a valuable update to the initial study conducted in Greek
inland waters 20 years ago [12].
The observed numerical predominance of males over females (1.7:1.0) was anticipated
due to the specific sampling method employed during the breeding season and within the
breeding fields of the species [
24
]. During this period, males construct nests and assume
the responsibility of guarding and protecting the fertilized eggs, which often leads to the
exclusion of females from the nesting area [
41
]. The analysis of condition factors, as well as
the estimation of the gonadosomatic index, revealed a distinct pattern for our study area. It
was observed that the pumpkinseed displayed its highest robustness in September, whereas
it was lowest during summer. Despite the lack of samples during spring, when the species
also reproduce, the highest values of the gonadosomatic index observed in both male and
females during July is supported by other studies [
12
,
42
,
43
]. Furthermore, it aligns with the
period when the system reaches the highest water temperature (21
◦
C) [
26
], which promotes
the initiation of species reproduction [
44
]. The deposition of reproductive material during
the summer is further supported by the fact that over 52.0% of the specimens were sexually
mature in all of the months except for October when the majority were immature (78.9%).
The above observations are further supported by comparing the robustness indices
with the gonadosomatic index (Figure 3B). The monthly variation of the robustness indices
exhibited an inverse pattern compared to the gonadosomatic index. Specifically, the
gonadosomatic index reached its maximum value in July, while the condition factors
exhibited their lowest values during this month. This can be attributed to the fact that
during the reproductive period in summer, freshwater fish allocate a significant amount of
energy towards the development of their gonads, which affects their overall body condition
and robustness [
45
,
46
]. This is further reinforced by the observation that in September
when all of the condition factors showed an increase, the value of the gonadosomatic index
was at its minimum. In contrast, a different pattern was observed in the artificial lake,
Kerkini [
12
], where the gonadosomatic index exhibited a consistent pattern of increasing
and decreasing values throughout the months.
The estimated total mortality was 1.63, with natural mortality estimated to be 0.829.
These mortality estimates are the first for the L. gibbosus in Mediterranean inland waters.
The standard deviation of natural mortality, which is equal to 0.245 [
47
], aligns with the
standard deviation of the Z value. This is to be expected given that pumpkinseed is not a
target of recreational fishing in the study area, as well as commercial fishing in the country’s
inland waters, where professional fishing is permitted [
48
], and the species is primarily
used as a decorative fish in aquariums [11].
Diversity 2023,15, 910 11 of 15
The growth rate of fish is influenced by external factors such as water temperature
and food availability, as well as internal factors related to the genetic characteristics of the
organisms [
45
]. The unique characteristics of the artificial lake of Aoos, being an alpine-type
lake located at a high altitude (1343 m) with significant temperature fluctuations (ranging
from 4
◦
C to 26
◦
C) and the potential for ice formation under extreme conditions [
26
], create
an ecosystem that hampers the growth of non-native species like the pumpkinseed. Water
temperature plays a crucial role in food intake and growth, as lower temperatures lead
to decreased growth rates [
45
]. Moreover, the system is characterized as an oligotrophic
lake [
26
], lacking in essential organisms that the pumpkinseed feeds on, such as benthic
invertebrates [
15
]. Consequently, these conditions favor the dominance of the small-sized
individuals of the species, as they require less food and energy to attain their needs [
49
].
This might suggest that the species follows a k-type survival strategy [
50
], characterized
by small body size, high growth rate, and shorter lifespan. This hypothesis is further
supported by the positioning of the present estimates in the left region of the L
∞
and
K relationship diagram in comparison to estimations from other inland water systems
in Europe and North America (Figure 5A). Thus, pumpkinseed might be adapted to
the extreme conditions of our study area by adopting a k-type strategy. The nests that
L. gibbosus
creates in the lakes range from 40 to 125 cm in diameter [
51
], while in the studied
system, their diameter ranges from 25 to 45 cm, which is related to the size of the male
individuals of the species that build the nests [52].
With respect to the low values of the gonadosomatic index, the lack of samples during
spring might bias the corresponding values, and this is the biggest drawback of the study.
Alternatively, we might assume that the low value of the gonadosomatic index estimated
in our study area is likely associated with the observed low growth rate, as discussed
earlier, which is influenced by the low temperatures characteristic of high-altitude alpine
lakes like the studied system. The low values of the gonadosomatic index might also
indicate that the pumpkinseed population in the high-altitude artificial lake of Aoos was
relatively low, possibly due to the limited biomass of its prey, such as benthic invertebrates.
Although pumpkinseed exhibited quite flexible feeding habits in response to changes in the
availability of food resources or environmental conditions along the invasion process [
53
,
54
],
it seemed that in the studied system, the prey of this species was at a low availability. In
general, the balance of pumpkinseed biomass in lake ecosystems is likely regulated by
trophic interspecific competition for available food resources [
55
–
57
]. Predatory fish species
like pike (Essox lucius) and pike-perch (Sander lucioperca (Linnaeus, 1758)) are known to
prey on pumpkinseed [58], and cannibalism has also been observed in certain cases [59].
Latitude consists of a limiting factor in fish growth, with organisms living at higher
latitudes tend to be larger and more robust than those near the equator in order to better
maintain their body temperature [
60
]. This pattern appears to apply to pumpkinseed in
European freshwater systems [
61
,
62
] (Figure 5B) and goes against the conclusions of this
study because the temperatures recorded in the studied system are low and similar to
those in areas at higher latitudes but with more accessible food resources (Table A2) [
63
].
Therefore, the smaller size of the pumpkinseed in the studied system is likely a result of
the nutritional constraints they experience, which hinder their growth and size increase.
5. Conclusions
According to the results of the present study, the pumpkinseed, despite being a non-
native species in the artificial lake of Aoos, has not managed to reach the sizes observed in
other European systems. This can be attributed to the unique biotic and abiotic characteris-
tics of this high-altitude artificial lake. There is a link between growth and temperature,
with organisms below their temperature optimum predicted to develop faster with in-
creasing temperature, while those above their temperature optimum are expected to grow
slower [
64
]. Given that the pumpkinseed exhibited a temperature range of 4
◦
C to 30
◦
C for
optimal growth [
16
] and the studied system experiences temperatures below 12
◦
C during
Diversity 2023,15, 910 12 of 15
a great part of the year [
26
], it is possible that an increase in temperature, possibly due to
climate change, could favor the growth of the species in the future.
Author Contributions:
Conceptualization, G.K. and D.K.M.; methodology, D.K.M.; formal analysis,
A.S.D.; investigation, A.S.D. and A.Z.; resources, A.S.D., A.Z., A.K., N.K. and N.P.; data curation,
A.S.D. and D.K.M.; writing—review and editing, A.S.D., A.K., G.K. and D.K.M.; supervision, D.K.M.;
project administration, N.K., A.K., N.P. and G.K.; funding acquisition, G.K. All authors have read and
agreed to the published version of the manuscript.
Funding:
This study was performed in the framework of the research project “implementation and
evaluation of management measures for the fish fauna of the artificial lake of Aoos with emphasis
on the sustainable management of the non-native species”, funded by the Management Agency of
the Northern Pindos National Park-Now Management Unit of the Northern Pindos National Park
under the Natural Environment and Climate Change Agency (N.E.C.C.A.), through the Operational
Program Transport Infrastructure Environment Sustainable Development, MIS 5033216.
Institutional Review Board Statement: Not applicable.
Data Availability Statement:
The data supporting the reported results of this study can be provided
upon request to the last author.
Acknowledgments:
The authors want to thank the staff of the Management Unit of Northern Pindos
National Park (N.E.C.C.A.), especially Antonios Stagogiannis and Athanassia Karambina, for their
involvement in the monitoring schemes, and the Public Power Corporation S.A. for providing their
boat and assisting in the fish sampling.
Conflicts of Interest: The authors declare no conflict of interest.
Appendix A
Table A1.
Estimated parameters of the length–weight relationship for pumpkinseed Lepomis gibbosus
in European freshwater systems.
Region Country Length
Type
Length
Range a b R2Year Reference
Aoos Springs Greece TL 24–101 0.012 3.190 0.985 2021 Present study
River Vit Bulgaria SL 33–92 0.024 3.187 0.963 2008 [65]
River Segura Spain TL 48–88 0.015 2.980 0.994 2000–2004 [37]
Lake Bara Croatia TL 0.013 3.140 0.991 2015 [66]
Catchment Basin Turkey TL 27–107 0.008 3.491 0.950 2014 [38]
Catchment Basin Turkey TL 39–132 0.013 3.138 0.987 2014 [38]
Table A2.
Growth parameters of the species pumpkinseed L. gibbosus in freshwater systems in Europe,
North America, and Canada. Formatted table of [22].
Region Country L∞k t0tmax ϕ0r2Year
Europe
Artificial Lake of Aoos (Present study) Greece 119 0.36 −0.31 8 3.707 0.691 2021
Tapada Pequena Reservoir Portugal 81.3 0.41 −0.151 7 3.43 0.995 1996
Tapada Grande Reservoir Portugal 112.5 0.16 −1.482 17 3.32 0.897 2004
Monte Novo Reservoir Portugal 101.1 0.50 −0.108 6 3.70 0.998 2004
Divor Reservoir Portugal 91.1 0.43 −0.550 6 3.56 0.989 1989
Artificial Lake Kerkini Greece 163.5 0.13 −2.729 20 3.53 1.000 1994
Lake Banyoles Spain 131.8 0.57 0.367 6 3.99 0.998 –
Fumemorte Canal France 113.6 0.34 0.013 9 3.65 0.997 2001
Sollac Marsh France 133.5 0.36 0.029 8 3.80 0.997 2001
Dabas Pond Hungary 94.9 0.38 −0.059 8 3.54 0.996 1977
Danube River Slovakia 168.3 0.23 −0.158 13 3.82 1.000 1973
Diversity 2023,15, 910 13 of 15
Table A2. Cont.
Region Country L∞k t0tmax ϕ0r2Year
Cottesmore Pond England 94.5 0.19 −0.721 15 3.23 0.996 2002
Odra River Poland 162.7 0.31 −0.584 9 3.92 0.994 –
North America
Deep Lake Michigan, USA 190.7 0.17 0.048 18 3.78 0.990 1948
Lower Dowsley Pond Ontario, CAN 174.2 0.24 0.195 13 3.87 1.000 1990
Opinicon Lake Ontario, CAN 184.5 0.14 −0.647 21 3.67 0.994 1990
Upper Poole Pond Ontario, CAN 145.5 0.21 −0.212 14 3.65 0.996 1990
Houghton Lake Michigan, USA 256.1 0.20 0.473 15 4.11 0.990 1926
Flora Lake Wisconsin, USA 205.5 0.16 −0.327 18 3.84 0.993 1958
Plastic Lake Ontario, CAN 180.0 0.16 0.124 19 3.74 0.970 1986
Crosson Lake Ontario, CAN 168.0 0.17 0.152 18 3.68 0.986 1986
Lake Upper Beverly Ontario, CAN 219.0 0.13 −0.026 23 3.78 0.992 1987
Lake Lower Beverly Ontario, CAN 125.3 0.26 −0.147 11 3.62 0.991 1987
Lake Vert Quebec, CAN 153.0 0.16 −0.054 19 3.58 0.982 1979
Lake Lower Loch Alpine Michigan, USA 142.8 0.18 −0.612 16 3.56 0.989 1977
A number of 55 lakes Wisconsin, USA 195.7 0.16 −0.588 18 3.79 0.995 1992
A number of 14 water bodies Pennsylvania, USA 160.1 0.23 0.393 13 3.78 0.982 1977
Unnamed Pond Michigan, USA 130.4 0.24 −0.802 12 3.62 0.997 1938
Unspecified Lake
North Carolina, USA
280.5 0.15 0.472 20 4.07 0.981 1997
Unspecified Lake New York, USA 175.5 0.24 0.386 13 3.86 0.995 1977
A number of 26 ponds Rhode Island, USA 172.6 0.27 0.247 11 3.91 0.999 1977
Multiple water bodies Delaware, USA 154.0 0.63 0.287 5 4.17 0.997 1997
Multiple streams
North Carolina, USA
237.0 0.17 0.312 18 3.98 0.978 1977
Multiple water bodies Illinois, USA 175.8 0.20 −1.639 13 3.79 0.988 1977
Multiple water bodies Ohio, USA 189.0 0.24 0.289 13 3.93 0.999 1977
Multiple water bodies Minnesota, USA 213.4 0.19 0.014 16 3.94 0.999 1977
Multiple water bodies Minnesota, USA 292.5 0.17 0.211 18 4.16 0.981 1977
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