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Morphometric characterization of adult Artemia (Crustacea: Branchiopoda) populations from costal and inland Tunisian salt lakes.

INTRODUCTION

The brine shrimp Artemia Leach, 1819 (Branchiopoda: Anostraca) comprises a number of bisexual species and parthenogenetic strains that are morphologically similar. Brine shrimps are found in inland and coastal saline and hypersaline waters throughout the world, with the exception of Antarctica (Triantaphyllidis et al. 1998; Van Stappen 2002). The present Artemia distribution is not only due to natural means (high dispersal potential of diapausing cysts) but also to human activity. Artemia species and strains have a remarkable genetic variability that can be expressed in various phenotypic characteristics such as morphometry, life history, breeding mechanisms and growth rate, according to their genetic differentiation and population structure (Gajardo et al. 2004; Munoz et al. 2008).

The taxonomic study of Artemia populations in the Western Old World, including Italy, the South of France and the Iberian Peninsula (Spain and Portugal), together with North Africa, is interesting owing to the presence of the Mediterranean bisexual Artemia salina (L., 1758) and at least two different parthenogenetic forms, diploid and tetraploid (Gilchrist 1960; Vieira & Amat 1985; Vanhaecke et al. 1987; Amat et al. 1995). This Mediterranean region also holds the recent invader species, Artemia franciscana Kellogg, 1906 (Narciso 1989; Amat et al. 1995; Amat et al. 2005; Mura et al. 2004; Amat et al. 2007; Scalone & Rabet 2013). In Tunisia, Artemia has been reported in 23 different locations, characterized as temporal or ephemeral catchments, and is distributed from semi-arid to Saharan hydrogeographical zones (Ben Naceur et al. 2009, 2010, 2012a). However, there is a paucity of data regarding their taxonomy, biogeography and genetic characteristics. Kaiser et al. (2006) published the most recent checklist of the zoogeography of Artemia and included eight Tunisian Artemia populations, three of which were cited as being of unknown specific identity.

The most relevant methods used for Artemia species characterization are the comparison of morphometric traits for specimens cultured under standard conditions (Hontoria & Amat 1992a, b; Gajardo et al. 1998; Amat et al. 2005; Mura et al. 2005), their genetic characterization (Zhang & King 1992; Abatzopoulos et al. 2002; Camargo et al. 2002; Kappas et al. 2004; Van Stappen et al. 2007; Munoz et al. 2008; Tizol-Correa et al. 2009), electron microscopic examination of some morphological traits (Criel & Macrae 2002; Mura & Nagorskaya 2005; Mura et al. 2005; Ben Naceur et al. 2011a), and cross-fertility tests (Gajardo et al. 2001; Abatzopoulos et al. 2002).

Although modern methods rely on genetic characterization through molecular markers for the differentiation of anostracan populations, it is well known that among Artemia, morphometrical traits have been the basis for describing species and strains (e.g. Hontoria & Amat 1992a, b; Triantaphyllidis et al. 1997; Camargo et al. 2003). Work on morphometrics of Artemia (Schmankewitsch 1873 in Litvinenko et al. 2007; Gaevskaya 1916; Gilchrist 1960; Ben Naceur et al. 2011b, 2012b) has shown that Artemia individuals exhibit morphological changes in accordance with environmental conditions. Moreover, Hontoria and Amat (1992a) reported that individuals from different Artemia populations, although similar in body shape, show morphological traits that enable morphometric differentiation when they are cultured under standard laboratory conditions.

In the present work, variation in different morphometric variables measured on adult Artemia specimens from Tunisian populations, and cultured under laboratory conditions, has been studied. Multivariate discriminant analysis has been used in order to support current knowledge on the taxonomic status of Artemia in these populations.

MATERIAL AND METHODS

Specimens from 16 Tunisian Artemia populations (Table 1) were cultured in the laboratory, characterized morphometrically, and compared with cultured specimens from two Artemia franciscana populations (San Francisco Bay, California, USA; and Great Salt Lake, Utah, USA).

Culture conditions

Experimental Artemia populations were reared under standardized culture conditions in order to minimize the strong environmental influences on body morphometry. Nauplii hatched from original cysts were reared up in 2-L plastic containers filled with 90 [+ or -] 10 g/L filtered and autoclaved brine (seawater plus crude sea salt) (Amat et al. 2005). Temperature was maintained at 24 [degrees]C during a 16 h light/8 h dark cycle. Shrimps were fed the unicellular alga Chlorella sp. at a density of 100-200 x [10.sup.3] cells/mL. The medium was renewed twice a week with a new microalgal culture.

Adult morphometry

As soon as specimens reached reproductive maturity (i.e. well-developed antennae on males and a well-developed brood pouch on females), a random sample of 20 individuals was removed from the culture (for each sex and population), anaesthetized with a few droplets of water saturated with chloroform and measured under a microscope using a calibrated micrometer eye piece. The following were measured for each male and female: total length (tl), abdominal length (al), width of third abdominal segment (wts), length of cercopods (Ic), number of setae on left cercopod (nlc), number of setae on right cercopod (nrc), width of head (wh), diameter of compound eyes (dy), maximal distance between compound eyes (dby), length of first antenna (la), width of brood pouch (wb) (for females), width of second abdominal segment (wss) and width of frontal knob (fk) (for males); abdomen length : total length ratio (ra, %) was also calculated for both sexes (Amat et al. 2005). The morphometric variability among the diverse populations was established by statistical treatment of data through one-way ANoVA (Tukey, P<0.05). The homogeneity of variances was tested using the Leven's test (Norusis 1993). Biometrical analysis of these data was performed via multivariate discriminant analysis using the statistical package SPSS for Windows, version 10.0 (Norusis 2000).

RESULTS

The statistically significant inter-population differences in morphometries have been observed for the male and female specimens (Tables 2, 3). Results of variance demonstrate different degrees of variation and do not show any particular similarity among the Artemia populations studied, apart from the width of the head of male specimens (F=1.088, P=0.360).

When the origin of populations was used as a separation factor for the multivariate discriminant analysis applied to morphometric data, this procedure showed 11 discriminant functions for males and 10 discriminant functions for females (Fig. 1, Table 4). The first five of these functions gave cumulative variance percentages of 85.7 % and 89.8 %o for males and females, respectively. Morphometric characteristics showed a clear differentiation between Tunisian populations (except that from Sabkhet Halk El Menzel) and the two reference populations.

The centroids (Fig. 1) demonstrate that populations belonging to the same species tend to be grouped. In the case of males (Table 5), the analysis shows that morphometric characters correlated with the first discriminant function are total length, length of cercopod, width of second abdominal segment and abdominal length. Those related to the second function are total length, abdominal length and total length and abdomen length / total body length ratio. For females, total length and abdominal length are morphometric traits correlated with the first discriminant function, while abdominal length, total length and abdomen length / total body length ratio, are related with the second function.

Tunisian Artemia populations, except for Sabkhet Halk El Menzel, were evidently grouped and separated from the two A. franciscana reference data sets (Fig. 1). Tunisian populations previously identified as A. salina (Table 1) were well integrated among unidentified Tunisian populations studied here, supporting their taxonomic assignment to the bisexual A. salina species. The Artemia population from Sabkhet Halk El Menzel was grouped with the two American populations and can be considered as belonging to the invasive A. franciscana species.

DISCUSSION

Morphometrical differentiation has been one of the most useful methods for Artemia taxonomy and biosystematics (Asem & Rastegar-Pouyani 2008). The results obtained here with multivariate discriminant analysis for 16 Tunisian Artemia populations and two American A. franciscana populations, using the origin of each population as a separation factor, provided two different phenotypic groups (the first group formed by populations identified as A. salina and unknown Artemia and the second group composed of the two American A. franciscana populations, together with the Tunisian population found in Sabkhet Halk El Menzel). Ben Naceur et al. (2011a, b) studied morphological characteristics (ovisac morphology in females and the frontal knob morphology and ornamentation (number of spines and mechanoreceptors), as well as the basal part of the penis, in males) of some Tunisian Artemia populations. Their results show that the male Artemia specimens from the Sabkhet Halk El Menzel population have a sub-spherical frontal knob shape, and spine-like projections present in the non-retractile basal part of the penis, leading to the conclusion that this population belongs to a species other than A. salina. In fact, based on the presence or absence of a spine on the basal part of penis, A. salina can be distinguished from all the other bisexual Artemia populations, since all non-Mediterranean bisexual Artemia (from both the New and the Old world) have spines basally on the penis (Triantaphyllidis et al. 1997; Mura & Nagorskaya 2005).

Several publications recently reported the presence of the invasive A. franciscana in different countries around Tunisia. This event was initially described in Portugal (Hontoria et al. 1987, in Amat et al. 2007), France (Thiery & Robert 1992; Scalone & Rabet 2013), Italy (Mura et al. 2004) and in Spain and Morocco (Amat et al. 2005; Green et al. 2005; Amat et al. 2007). The occurrence of A. franciscana in Portuguese hypersaline water bodies might date from the 1980s, and although the time and the place of the original introduction remain unknown, the introduction could have been intentional (Amat et al. 2007), especially as the beneficial effect of the branchiopod Artemia in salt production and their use in aquaculture as a food source were well known (Dhont & Sorgeloos 2002). This species was probably then dispersed via waterfowl northwards along the East Atlantic flyway (Green et al. 2005) and eastwards, reaching the Spanish, Moroccan and Italian sites where it was found (Amat et al. 2007). This hypothesis about the natural dispersion of A. franciscana via water birds should not be dismissed in the light of intentional inoculations carried out in industrial salt pans exploited around the Mediterranean basin (Amat et al. 2007). Concerning the Tunisian Artemia populations, the results obtained herein suggest that Artemia harvested from Sabkhet Halk El Menzel belongs to the invasive A. franciscana. Ben Naceur et al. (2009) prepared a previous check list on the distribution of Artemia in Tunisia and signalled the presence of this branchiopod in 21 sites, with the exception of the Sabkhet Halk El Menzel population. Furthermore, Sabkhet Halk El Menzel has the main marine aquaculture (fish farm) in Tunisia, in its southeast part. This private farm, concerned with the intensive production of sea bass and sea bream, includes a hatchery where commercial Artemia cysts are used to obtain brine shrimp nauplii for feeding fish larval stages.

In conclusion, all Tunisian Artemia populations, except that from Sabkhet Halk El Menzel, were identified as A. salina. The new Artemia population from Sabkhet Halk El Menzel can be considered to be the invasive A. franciscana. However, other methods must be used (such as monitoring of reproduction and genetic characterization) to confirm the taxonomic status of the Artemia population from Sabkhet Halk el Menzel. The time and origin of the introduction there of this exotic species are unknown but aquaculture activities should be suspected as having been responsible.

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Hachem Ben Naceur *, Amel Ben Rejeb Jenhani and Mohamed Salah Romdhane

Research Unit of Ecosystems and Aquatic Resources, National Institute of Agricultural Sciences of Tunisia, University of Carthage, 43 Av. Charles Nicolle, 1082 Tunis Mahrajene, Tunisia; hachem_b_naceur@yahoo.fr

* Corresponding author

TABLE 1

Sources of Tunisian Artemia populations used for morphometrical
characterization and literature references for autochthonous
populations with verified species status.

Site                Habitat        Abbreviation      Co-ordinates

Sabkhet        Inland salt lake        SIJ         36[degrees]55'38"
Sijoumi                                           N10[degrees]15'22"E

Megrine        Coastal saltwork        MEG          36[degrees]47'
saltwork                                           N10[degrees]14'E

Sabkhet        Inland salt lake        KOR         36[degrees]24'47"
Korzia                                            N09[egrees]47'10"E

Sabkhet Halk   Coastal salt lake        HM         36[degrees]00'40"
El Menzel                                         N10[degrees]27'30"E

Sabkhet Sidi   Inland salt lake         SH         35[degrees]37'43"
El Eiani                                          N10[degrees]22'46"E

Sahline        Coastal saltwork       SAH03        35[degrees]45'58"
saltwork

                                      SAH06       N10[degrees]46'58"E

Bkalta         Coastal saltwork         BK         35[degrees]34'9"
saltwork                                          N11[degrees]01'39"E

Sabkhet        Inland salt lake        MOK         35[degrees]36'20"
Moknine                                           N10[degrees]55'37"E

Sfax           Coastal saltwork        SFX          34[degrees]42'
saltwork                                             24[degrees]"
                                                  N10[degrees]44'14"E

Sabkliet       Inland salt lake         BJ         34[degrees]57'53"
Boujmal                                           N10[degrees]24'04"E

Sabkliet       Inland salt lake        MCH         34[degrees]57'16"
Mcheguig                                          N10[degrees]02'28"E

Sabkhet         Inland saltwork       ADH 03       33[degrees]05'42"
El Adhibet

                                      ADH 07      N11[degrees]24'29"E

Sabkliet       Inland salt lake        MNK         33[degrees]08'59"
Mnikhra                                           N11[degrees]20'09"E

Mhabeul         Inland saltwork        MHB         33[degrees]24'35"
saltwork                                          N10[degree]51'20"E

Sabkhet        Inland salt lake        MEL         32[degrees]21'34"
El Melah                                          N10[degrees]55'22"E

Zarzis          Inland saltwork        ZAR         33[degrees]24'48"
saltwork                                          N11[degrees]03'43"E

San                   --               SFB                --
Francisco
Bay

Great Salt            --               GSL                --
Lake

Site           Year      Species          References

Sabkhet        2003     A. salina        Romdhane et
Sijoumi                                    al. 2004

Megrine        1998     A. salina        Romdhane et
saltwork                                   al. 2004

Sabkhet        2006     A. salina       Ben Naceur et
Korzia                                    al. 2011a

Sabkhet Halk   2009      Species              --
El Menzel                 status
                         unknown

Sabkhet Sidi   2006      Species              --
El Eiani                  status
                         unknown

Sahline        2003     A. salina      Romdhane et al.
saltwork                                2004 Munoz et
                                           al. 2008

               2006      Species              --
                          status
                         unknown

Bkalta         2007      Species              --
saltwork                  status
                         unknown

Sabkhet        2006      Species              --
Moknine                   status
                         unknown

Sfax                    A. salina
saltwork

Sabkliet       2008     A. salina       Ben Naceur et
Boujmal                                   al. 2011a

Sabkliet       2006      Species              --
Mcheguig                  status
                         unknown

Sabkhet        2003     A. salina        Romdhane et
El Adhibet                              al. 2004 Munoz
                                         et al. 2008

               2007     A. salina        BenNaceur et
                                          al. 20116

Sabkliet       2007     A. salina        BenNaceur et
Mnikhra                                   al. 2011a

Mhabeul        2006      Species              --
saltwork                  status
                         unknown

Sabkhet        2006     A. salina       Ben Naceur et
El Melah                                  al. 2011a

Zarzis         2006      Species              --
saltwork                  status
                         unknown

San             --    A. franciscana   Commercial cysts
Francisco
Bay

Great Salt      --    A. franciscana   Commercial cysts
Lake

TABLE 2

Mean values 'mm' (standard deviation in parentheses) of
morphometric characters measured in males of different Tunisian
Artemia populations. Total length (tl), abdominal length (al),
width of second abdominal segment width of third abdominal segment
(wts), length of cercopods (lc), number of setae inserted on left
cercopod (nlc), number of setae inserted on right cercopod (nrc),
width of head (wh), maximal distance between compound eyes (dby),
diameter for compound eyes (dy), length of first antenna (la),
width of frontal knob (jk) and abdomen length : total length ratio
(ra, %). Abbreviations for populations are explained in Table 1.
Same letters show non-significant differences between mean in each
row of main column (P=0.05).

                 tl               al             W55

SIJ         8.17 (abcd)     4.11 (defghi)    0.47 (cde)
               (0.77)           (0.34)         (0.05)
MEG          7.98 (abf)     3.78 (bcdefg)     0.52 (ef)
               (0.78)           (0.37)         (0.09)
KOR           9.24 (g)        4.42 (hij)      0.54 (f)
               (0.55)           (0.27)         (0.05)
HM           8.10 (abc)       3.41 (ab)       0.50 (ef)
               (0.63)           (0.39)         (0.07)
SH          8.88 (cdefg)     4.17 (efghi)    0.41 (abc)
               (1.15)           (0.49)         (0.05)
SAH03       8.90 (cdefg)     4.19 (fghi)      0.54 (f)
               (0.62)           (0.23)         (0.05)
SAH06       8.52 (abcdef)   3.96 (cdefgh)    0.44 (abcd)
               (0.47)           (0.33)         (0.03)
BK         8.71 (abcdefg)     4.24 (ghi)      0.39 (ab)
               (0.58)           (0.33)         (0.03)
MOK        8.53 (abcdef)    4.03 (cdefghi)    0.38 (a)
               (0.66)           (0.67)         (0.05)
SFX           9.42 (g)       4.18 (fghi)      0.52 (ef)
               (0.88)           (0.42)         (0.07)
BJ           9.13 (efg)       4.50 (ij)       0.50 (ij)
               (0.77)           (0.43)         (0.05)
MCH         8.17 (abcd)      3.71 (bcde)     0.41 (abc)
               (0.74)           (0.37)         (0.05)
ADH 03      9.03 (defg)     4.06 (cdefghi)   0.44 (bcd)
               (0.72)           (0.36)         (0.04)
ADH 07        7.89 (a)       3.73 (bcdef)    0.41 (abc)
               (0.65)           (0.33)         (0.03)
MNK          9.13 (efg)        4.79 (j)      0.50 (def)
               (0.77)           (0.42)         (0.05)
MHB          7.95 (ab)       3.67 (abcd)     0.41 (abc)
               (0.73)           (0.40)         (0.03)
MEL         8.37 (abcde)     3.95 (cdefg)     0.40 (ab)
               (0.93)           (0.45)         (0.04)
ZAR        8.79 (bcdefg)     3.94 (cdefg)    0.44 (bcd)
               (1.21)           (0.54)         (0.06)
GSL          8.09 (abc)        3.22 (a)       0.51 (ef)
               (0.88)           (0.53)         (0.04)
SFB           7.89 (a)        3.63 (abc)      0.54 (f)
               (0.45)           (0.34)         (0.06)
F-value        8.316            15.967         22.416
P-value        0.000            0.000           0.000

               wts             lc             nlc             nrc

SIJ        0.40 (cdefg)     0.32 (bc)     8.95 (abcd)     9.25 (abc)
              (0.04)         (0.07)          (3.39)         (3.46)
MEG        0.38 (efgh)     0.38 (efgh)    10.75 (abcd)   10.60 (abcde)
              (0.06)         (0.07)          (4.12)         (3.80)
KOR          0.43 (i)       0.47 (ab)       7.90 (a)       8.20 (ab)
              (0.05)          (0.1)          (5.39)         (5.61)
HM           0.43 (a)      0.16 (abcd)     9.15 (abc)     9.05 (abcd)
              (0.03)         (0.05)          (3.32)         (3.83)
SH         0.40 (defgh)    0.37 (def)     13.00 (cde)     13.00 (cde)
              (0.06)          (0.1)          (5.52)         (5.34)
SAH03      0.46 (fghi)    0.40 (abcde)     9.25 (abc)    9.05 (abcde)
              (0.03)         (0.06)          (1.80)         (1.76)
SAH06      0.42 (defgh)   0.35 (bcdef)    11.60 (abcd)   11.35 (bcdef)
              (0.04)         (0.08)          (4.18)         (3.95)
BK          0.36 (bcd)      0.29 (ab)       8.05 (a)       8.10 (ab)
              (0.04)         (0.05)          (2.25)         (2.29)
MOK         0.36 (ab)     0.22 (abcde)    10.05 (abcd)   10.50 (abcde)
              (0.04)          (0.1)          (3.63)         (4.00)
SFX         0.46 (ghi)    0.41 (abcde)    10.55 (abcd)   10.85 (abcde)
              (0.05)         (0.07)          (2.56)         (2.62)
BJ         0.44 (bcde)      0.30 (ab)      8.40 (ab)       8.40 (ab)
              (0.04)         (0.08)          (2.43)         (2.60)
MCH         0.40 (hi)       0.44 (f)       15.05 (e)       15.50 (f)
              (0.04)         (0.06)          (3.08)         (3.25)
ADH 03     0.44 (cdef)     0.32 (abcd)     9.10 (abc)     9.05 (abed)
              (0.04)         (0.07)          (1.97)         (1.82)
ADH 07      0.39 (abc)      0.24 (a)        7.35 (a)       7.40 (a)
              (0.03)         (0.06)          (1.87)         (1.78)
MNK        0.44 (bcde)      0.30 (ab)      8.40 (ab)       8.40 (ab)
              (0.05)         (0.08)          (2.43)         (2.60)
MHB        0.40 (fghi)      0.39 (ef)      13.15 (de)     13.05 (ef)
              (0.03)          (0.1)          (3.77)         (3.85)
MEL        0.38 (defgh)    0.35 (cdef)    12.35 (bcde)   12.25 (cdef)
              (0.04)         (0.08)          (5.00)         (4.66)
ZAR        0.40 (defg)    0.34 (abcde)    10.10 (abcd)   10.10 (abcde)
              (0.05)          (0.1)          (3.49)         (3.47)
GSL          0.45 (a)     0.20 (abcde)    0.70 (abcd)    9 55 (abcde)
              (0.05)          (0.1)          (3.43)         (3.91)
SFB         0.47 (ab)     0.21 (abcde)    11.10 (abcd)   11.00 (abcde)
              (0.06)         (0.04)          (3.30)         (3.35)
F-value       10.825         22.827          6.575           6.538
P-value       0.000           0.000          0.000           0.000

              wh           dby              dy             la

SIJ        0.73 (a)   1.46 (bcdef)    0.33 (bcdefg)    0.97 (bcde)
            (0.04)       (0.15)           (0.03)         (0.12)
MEG        0.66 (a)    1.55 (efg)     0.35 (f)s (h)    1.03 (def)
            (0.20)       (0.13)           (0.04)         (0.11)
KOR        0.72 (a)     1.58 (fg)       0.36 (gh)       1.05 (ef)
            (0.26)       (0.18)           (0.04)         (0.17)
HM         0.60 (a)     1.27 (a)         0.28 (a)       0.69 (a)
            (0.07)       (0.17)           (0.06)         (0.13)
SH         0.96 (a)   1.49 (bcdef)     0.34 (defgh)    0 98 (bcde)
            (1.23)       (0.27)           (0.05)         (0.14)
SAH03      0.81 (a)     1.71 (g)         0.38 (h)       1.13 (f)
            (0.04)       (0.09)           (0.02)         (0.10)
SAH06      0.73 (a)    1 52 (cdef)    0.33 (bcdefg)    0.94 (bcde)
            (0.03)       (0.07)           (0.02)          (0.1)
BK         0.70 (a)     1.32 (ab)       0.29 (ab)       0.87 (bc)
            (0.04)       (0.10)           (0.02)         (0.09)
MOK        0.62 (a)    1.36 (abcd)    0.31 (abedef)    0.91 (bcd)
            (0.06)       (0.11)           (0.03)         (0.11)
SFX        0.82 (a)     1.55 (fg)      0.34 (efgh)      1.07 (ef)
            (0.07)       (0.14)           (0.05)         (0.13)
BJ         0.78 (a)    1.53 (defg)    0.33 (bcdefg)     1.14 (f)
            (0.06)       (0.15)           (0.03)         (0.12)
MCH        0.72 (a)   1.45 (bcdef)    0.32 (bcdefg)    1.03 (def)
            (0.06)       (0.16)           -0.04          (0.09)
ADH 03     0.73 (a)    1.52 (cdef)     0.34 (defgh)     1.06 (ef)
            (0.07)       (0.18)           (0.05)         (0.10)
ADH 07     0.68 (a)   1.47 (bcdef)    0.34 (cdefgh)    1.01 (cdef)
            (0.05)        (0.1)           (0.02)         (0.08)
MNK        0.78 (a)    1.53 (defg)    0.33 (bcdefg)     1.14 (f)
            (0.06)       (0.15)           (0.03)         (0.12)
MHB        0.68 (a)    1.344 (abc)     0.30 (abcd)     0.95 (bcde)
            (0.05)       (0.13)           (0.03)         (0.12)
MEL        0.94 (a)   1.42 (abcdef)   0 33 (bcdefg)    0.95 (bcde)
            (1.2)        (0.22)           (0.04)         (0.11)
ZAR        0.73 (a)   1.48 (bcdef)    0 32 (abcdef)    1.03 (def)
            (0.08)       (0.19)           (0.06)         (0.19)
GSL        0.67 (a)   1.37 (abcde)     0 31 (abcde)    0.93 (bcde)
            (0.07)       (0.16)           (0.04)         (0.17)
SFB        0.67 (a)     1.32 (ab)       0.30 (abc)      0.85 (b)
            (0.03)       (0.14)           (0.06)         (0.11)
F-value     1.088         8.981           8.531          14.432
P-value     0.360         0.000           0.000           0.000

                 fk            ra (%)

SIJ          0.16 (cde)      50.46 (gh)
               (0.02)          (2.93)
MEG          0.19 (ghi)     47.49 (cdefg)
               (0.02)          (3.82)
KOR          0.19 (hi)      47.94 (defg)
               (0.02)          (2.03)
HM            0.1 (ab)       42.06 (ab)
               (0.03)          (3.25)
SH           0.15 (bcd)     47.11 (cdef)
               (0.02)          (2.11)
SAH03         0.20 (i)      47 14 (cdef)
               (0.02)          (2.15)
SAH06       0.17 (cdefg)    46.50 (cdef)
               (0.02)          (2.32)
BK          0.15 (abcd)      48.67 (efg)
               (0.01)          (1.60)
MOK         0.16 (cdef)     47.22 (cdef)
               (0.03)          (6.23)
SFX           0.20 (i)       44.38 (bc)
               (0.03)          (1.96)
BJ          0.19 (fghi)      49.28 (fgh)
               (0.02)          (3.00)
MCH         0.16 (bcde)      45.45 (cd)
               (0.02)          (2.81)
ADH 03      0.18 (efghi)     45.05 (bcd)
               (0.02)          (2.18)
ADH 07      0.16 (bcde)     47.29 (cdefg)
               (0.01)          (2.58)
MNK         0.19 (fghi)       52.40 (h)
               (0.02)          (1.15)
MHB         0.15 (abcd)     46.17 (cdef)
               (0.02)          (1.78)
MEL          0.14 (abc)     47 26 (cdefg)
               (0.02)          (2.19)
ZAR         0.27 (defgh)    44.87 (bcd)
               (0.03)          (2.12)
GSL          0.15 (bcd)       39.68 (a)
               (0.03)          (2.81)
SFB           0.12 (a)       46.08 (cde)
               (0.02)          (3.99)
F-value        19.128          18.642
P-value        0.000            0.000

TABLE 3

Mean values "mm" (standard deviation in parentheses) of
morphometric characters measured in females of different Tunisian
Artemia populations. Total length (--), abdominal length (al),
width of brood pouch (wb), width of third abdominal segment (wts),
length of cercopods (lc), number of setae inserted on left cercopod
(nlc), number of setae inserted on right cercopod (nrc), width of
head (wh), maximal distance between compound eyes (dby), diameter
for compound eyes (dy), length of first antenna (la), and abdomen
length : total length ratio (ra, %). Abbreviations for populations
are explained in Table 1. Same letters show non-significant
differences between mean in each row of main column (P=0.05).

                tl               al               wb

SIJ          8.80 (ab)      4.68 (abcde)     1.35 (abcdef)
              (0.79)           (0.39)           (0.17)
MEG          8.74 (a)        4.59 (abcd)     1.52 (cdefg)
              (0.46)           (0.35)           (0.23)
KOR        9.37 (abcde)      5.03 (cdef)      1,30 (abcd)
              (0.69)           (0.49)           (0.18)
HM         9.84 (cdefgh)     4.59 (abcd)       1.21 (ab)
              (0.65)           (0.56)           (0.11)
SH         10.28 (efgh)      5.26 (f)        1.32 (abcd)
              (1.37)           (0.74)           (0.34)
SAH 03      8.95 (abc)      4.88 (abcdef)     1.61 (efg)
              (0.63)           (0.53)           (0.32)
SAH 06       8.76 (ab)        4.44 (ab)       1.31 (abcd)
              (0.68)           (0.41)           (0.14)
BK         10.13 (efgh)       5.30 (f)       1.74 (abcde)
              (0.63)           (0.32)           (0.20)
MOK        9.91. (defgh)     5.13 (def)       1,28 (abc)
              (0.86)           (0.67)           (0.20)
SFX         10.43 (gh)       5.21 (def)       1.56 (defg)
              (0.64)           (0.43)           (0.19)
BJ         10.06 (efgh)     4.94 (bcdef)       1.17 (a)
              (0.82)           (0.34)           (0.25)
MCH        (g).99 (abcd)      4.35 (a)         1.21 (ab)
ADH 03     9.49 (abcdef)     4.64 (abcd)    1.39 (abcdefg)
              (0.80)           (0.45)           (0.24)
ADH 07      8.95 (abc)      4.79 (abcdef)   1.37 (abcdefg)
              (0.51)           (0.39)           (0.22)
MNK         10.40 (fgh)      5.13 (def)        1.61 (fg)
              (0.86)           (0.49)           (0.35)
MHB         8.99 (abc)       4.49 (abc)       1.29 (abcd)
              (0.88)           (0.52)           (0.28)
MEL         9.96 (efgh)      5.10 (def)     1.39 (abcdefg)
              (0.95)           (0.53)           (0.25)
ZAR        9.67 (bcdefg)    4.76 (abcdef)    1.46 (gbcdefg)
              (1.01)           (0.64)           (0.31)
GSL         10.30 (fgh)      4.62 (abcd)     1.55 (cdefg)
              (1.15)           (0.59)           (0.28)
SFB          10.60 (h)       5.11 (def)        1.62 (g)
              (0.84)           (0.51)           (0.18)
F-value       12.217            6.936            6.745
P-value        0.000            0.000            0.000

             wts           lc            nlc               nrc

SIJ       0.43 (ab)    0.28 (cd)     7.20 (abcde)     0.77 (abcdef)
            (0.03)       (0.08)         (2.56)           (2.46)
MEG       0.45 (ab)    0.36 (ef)     10.50 (efgh)     10.65 (ghij)
            (0.04)       (0.09)         (4.68)           (4.82)
KOR       0.43 (ab)    0.21 (abc)      4.20 (a)         4.20 (a)
            (0.04)       (0.08)         (3.30)           (3.23)
HM        0.47 (ab)     0.17 (a)     9.25 (defg)      9.30 (defghi)
            (0.05)       (0.05)         (3.25)           (3.55)
SH        0.45 (ab)    0.26 (bcd)   7.85 (bcdefg)    7.90 (bcdefghi)
            (0.07)       (0.05)         (3.32)           (3.32)
SAH 03    0.52 (abc)   0.24 (bcd)     5.10 (abc)       5.15 (abc)
            (0.08)       (0.05)         (1.74)           (1.72)
SAH 06    0.44 (ab)    0.28 (cd)     10.50 (efgh)     10.45 (fghij)
            (0.05)       (0.06)         (2.52)           (2.68)
BK         0.42 (a)    0.26 (bcd)    6.65 (abcd)      6.80 (abcde)
            (0.03)       (0.05)         (2.47)           (2.37)
MOK       0.47 (ab)    0.24 (bcd)    7.75 (bcdef)    7.75 (bcdefgh)
            (0.07)       (0.08)         (4.10)           (4.25)
SFX       0.51 (abc)    0.38 (f)      11.35 (gh)       11.40 (ij)
            (0.05)       (0.07)         (3.29)           (3.31)
BJ        0.54 (abc)   0.23 (abc)    8.35 (cdefg)    8.50 (cdefghi)
            (0.08)       (0.06)         (2.05)           (1.93)
MCH       0.44 (ab)     0.39 (f)      13.10 (h)         13.15 (j)
ADH 03    0.47 (ab)    0.26 (bcd)    6.10 (abcd)       6.15 (abcd)
            (0.05)       (0.08)         (2.51)           (2.51)
ADH 07    0.45 (ab)    0.19 (ab)      4.70 (ab)         4.85 (ab)
            (0.03)       (0.04)         (1.45)           (1.38)
MNK       0.55 (bc)    0.25 (bcd)    7.15 (abcde)    0.25 (abcdefg)
            (0.09)       (0.05)         (3.04)           (3.27)
MHB       0.46 (ab)    0.30 (de)     11.200 (fgh)      11.15 (hij)
            (0.06)       (0.09)         (5.33)           (5.31)
MEL       0.46 (ab)    0.26 (bcd)   7.85 (bcdefg)    7.90 (bcdefghi)
            (0.06)       (0.05)         (3.32)           (3.32)
ZAR       0.49 (abc)   0.29 (de)     8.90 (defg)      8.85 (defghi)
            (0.05)       (0.07)         (2.98)           (3.09)
GSL        0.61 (c)    0.20 (ab)     10.25 (efgh)    10.05 (efghij)
            (0.08)       (0.04)         (2.31)           (2.21)
SFB        0.61 (c)    0.24 (abc)    10.90 (fgh)      10.75 (ghij)
            (0.04)       (0.05)         (1.99)           (1.88)
F-value     4.712        15.932         12.039           11.649
P-value     0.000        0.000          0.000             0.000

               wh             dby            dy            la

SIJ       0.77 (bcdef)    1,26 (abc)     0.22 (abc)    0.63 (abc)
             (0.04)          (0.1)         (0.02)        (0.10)
MEG       0.76 (bcdef)    1,26 (abc)    0.23 (bcdef)   0.63 (abc)
             (0.06)         (0.08)         (0.01)        (0.06)
KOR         0.69 (a)       1.16 (a)       0.21 (a)     0.62 (abc)
             (0.08)         (0.09)         (0.01)        (0.05)
HM         0.71 (abcd)     1.23 (ab)    0.23 (abcd)    0.64 (abcd)
             (0.05)         (0.08)         (0.02)        (0.05)
SH         0.74 (abcd)    1.32 (bcde)    0.24 (def)    0.67 (abcd)
             (0.05)         (0.13)         (0.02)        (0.06)
SAH 03    0.75 (abcdef)   1,25 (abc)     0.24 (def)    0.65 (abcd)
             (0.06)         (0.14)         (0.02)        (0.09)
SAH 06     0.73 (abcd)    1,26 (abc)     0.23 (bcd)    0.62 (abc)
             (0.04)         (0.08)         (0.01)        (0.07)
BK        0.70 (abcdef)    1.22 (ab)     0.22 (abc)    0.67 (abcd)
             (0.04)         (0.06)         (0.01)        (0.08)
MOK        0.70 (abc)     1,27 (abc)     0.22 (abc)     0.75 (d)
             (0.09)         (0.19)         (0.02)        (0.24)
SFX         0.85 (g)      1.37 (cde)     0.25 (efg)     0.72 (cd)
             (0.05)         (0.09)         (0.02)        (0.08)
BJ        0.78 (cdefg)    1.27 (abcd)    0.23 (bcd)    0.65 (abcd)
             (0.05)         (0.08)         (0.01)        (0.08)
MCH        0.74 (abcd)     1.23 (ab)     0.23 (bcd)    0.65 (abcd)
ADH 03    0.74 (abcde)    1.29 (bcde)   0.24 (cdef)    0.69 (abcd)
             (0.07)         (0.12)         (0.02)        (0.09)
ADH 07      0.70 (ab)     1.25 (abc)    0.23 (abcd)     0.59 (a)
             (0.03)         (0.07)         (0.02)        (0.06)
MNK         0.82 (fg)      1.40 (de)     0.25 (fg)       0.7511
             (0.07)         (0.12)         (0.02)        (0.08)
MHB        0.73 (abcd)    1,25 (abc)    0.24 (cdef)    0.62 (abc)
             (0.11)         (0.17)         (0.03)        (0.10)
MEL        0.74 (abcd)    1.32 (bcde)    0.24 (def)    0.67 (abcd)
             (0.05)         (0.13)         (0.02)        (0.06)
ZAR        0.73 (abcd)    1,25 (abc)    0.23 (bcde)    0.69 (abcd)
             (0.09)         (0.14)         (0.03)        (0.10)
GSL        0.79 (defg)    1.36 (cde)    0.24 (cdef)    0.70 (bcd)
             (0.08)         (0.10)         (0.02)        (0.07)
SFB        0.81 (efg)      1.41 (e)       0.27 (g)      0.60 (ab)
             (0.05)         (0.09)         (0.02)        (0.07)
F-value       7.976         10.698         6.310          4.347
P-value       0.000          0.000         0.000          0.000

             ra (%)

SIJ        53.29 (gh)
             (3.64)
MEG        52.55 (fgh)
             (3.57)
KOR        53.70 (gh)
             (2.31)
HM         46.52 (ab)
             (2.91)
SH        51.18 (defg)
             (1.98)
SAH 03      54.46 (h)
             (3.30)
SAH 06    50.68 (cdefg)
             (2.06)
BK         52.40 (fgh)
             (1.16)
MOK       51.69 (efgh)
             (3.94)
SFX       49.97 (cdef)
             (2.38)
BJ        49.18 (bcde)
             (2.27)
MCH        48.33 (bcd)
ADH 03    48.94 (bcde)
             (2.22)
ADH 07     53.51 (gh)
             (1.86)
MNK       49.28 (bcde)
             (1.78)
MHB       49,97 (cdef)
             (2.37)
MEL       51.21 (defg)
             (2.07)
ZAR       49.29 (bcde)
             (5.32)
GSL         44.82 (a)
             (1.66)
SFB        48.13 (bc)
             (1.78)
F-value      17.211
P-value       0.000

TABLE 4

Results for discriminant analysis based on morphometrical traits
for Artemia populations from Tunisia, with the two commercial A.
franciscana populations used as reference.

                         Percent of   Cumulative    Canonical
Function   Eigen-value    variance     percent     correlation

Males
1             2.512         34.3         34.3         0.846
2             1.556         21.3         55.6         0.780
3             0.996         13.6         69.2         0.706
4             0.645          8.8         78.1         0.626
5             0.556          7.6         85.7         0.598
6             0.417          5.7         91.4         0.543
7             0.242          3.3         94.7         0.441
8             0.143          1.9         96.6         0.353
9             0.109          1.5         98.1         0.313
10            0.092          1.3         99.4         0.290
11            0.047          0.6        100.0         0.212
Females
1             2.077         39.9         39.9         0.822
2             1.062         20.4         60.3         0.718
3             0.733         14.1         74.3         0.650
4             0.464          8.9         83.3         0.563
5             0.340          6.5         89.8         0.504
6             0.238          4.6         94.3         0.438
7             0.117          2.2         96.6         0.324
8             0.087          1.7         98.3         0.283
9             0.065          1.3         99.5         0.248
10            0.025          0.5        100.0         0.157

           Wilks'
Function   Lambda   Chi-square

Males
1          0.009     1825.874
2          0.030     1344.078
3          0.077      984.162
4          0.153      719.041
5          0.252      528.109
6          0.393      358.567
7          0.556      224.829
8          0.691      141.824
9          0.789       90.731
10         0.875       51.202
11         0.955       17.580
Females
1          0.028     1369.788
2          0.087      938.212
3          0.179      660.234
4          0.311      449.100
5          0.455      302.719
6          0.609      190.273
7          0.754      108.424
8          0.842       65.946
9          0.915       33.920
10         0.975        9.573

TABLE 5

Standardized coefficients for the first two discriminant functions
and correlated morphometrical traits. Abbreviations for
morphometric characters are explained in Tables 2 and 3.

                     Males

Morphometrical   First function   Second function
variables
tl                   -0.656           -1.914
al                    0.612            1.251
wss                  -0.452            0.984
wts                  -0.328           -0.023
lc                    0.695           -0.058
nrc                  -0.395           -0.157
dby                   0.217            0.389
dy                    0.099           -0.232
la                    0.358            0.305
fk                    0.348            0.228
ra (%)                0.072           -0.555

                    Females

Morphometrical   First function   Second function
variables

tl                   -2.673           11.592
al                   -2.349           -2.621
wb                   -0.432            0.308
lc                   -0.673            0.297
nlc                   0.482            0.315
wh                   -0.470            0.471
dby                   0.361           -0.218
dy                    0.272            0.525
la                   -0.071           -0.468
ra (%)                0.550            1.003
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Article Details
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Author:Naceur, Hachem Ben; Jenhani, Amel Ben Rejeb; Romdhane, Mohamed Salah
Publication:African Invertebrates
Article Type:Report
Geographic Code:6TUNI
Date:Dec 1, 2013
Words:7051
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