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“Gone with the wind”: Fatty acid biomarkers and chemotaxonomy of stranded pleustonic hydrozoans (Velella velella and Physalia physalis)


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Marine pleustonic species such as the hydrozoans Velella velella and Physalia physalis, are known to drift in the world's oceans driven by winds, currents and tides. Here we present the first chemotaxonomic characterization, based on the fatty acid (FA) profile, of these two charismatic oceanic species that thrive in the interface layer between air and the water column in adult stages. Moreover, we compared their FA profiles with those from other representative cnidarian orders (Rhizostomeae, Anthomedusae, Siphonophorae, Alcyonacea, Scleractinia, Helioporacea and Pennatulacea). Velella velella and P. physalis mainly differed in the presence of symbiotic dinoflagellates markers (18:3n-6, 18:4n-3 and 20:5n-3 polyunsaturated FAs), present in higher percentage in the former, and bacterial markers (odd-numbered, branched and 18:1n-7 FAs), which were more representative in the latter. When comparing these species' FA profiles with the ones of other cnidarians orders, the presence/absence of endosymbionts and of specific FAs (tetracosapentaenoic and tetracosahexaenoic acids) as well as the latitudinal habitats were the main drivers for the distinction between groups.
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Gone with the wind: Fatty acid biomarkers and
chemotaxonomy of stranded pleustonic hydrozoans
(Velella velella and Physalia physalis)
Ana Rita Lopes
, Miguel Baptista
es C. Rosa
, Gisela Dionísio
e Gomes-Pereira
, Jos
e Ricardo Paula
atia Figueiredo
Narcisa Bandarra
, Ricardo Calado
, Rui Rosa
MARE eMarine and Environmental Sciences Centre, Faculdade de Ci^
encias da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa,
Departamento de Biologia &CESAM, Universidade de Aveiro, Campus Universit
ario de Santiago, 3810-193 Aveiro, Portugal
Centre of IMAR and Department of Oceanography and Fisheries, University of the Azores, 9901-862 Horta, Portugal
Departamento de Inovaç~
ao Tecnol
ogica e Valorizaç~
ao dos Produtos da Pesca, IPIMAR/IPMA, Avenida de Basília, 1449-006 Lisboa,
article info
Article history:
Received 10 August 2015
Received in revised form 25 March 2016
Accepted 27 March 2016
Fatty acids
Velella velella
Physalia physalis
Pleustonic hydrozoans
Marine pleustonic species such as the hydrozoans Velella velella and Physalia physalis, are
known to drift in the world's oceans driven by winds, currents and tides. Here we present
the rst chemotaxonomic characterization, based on the fatty acid (FA) prole, of these
two charismatic oceanic species that thrive in the interface layer between air and the
water column in adult stages. Moreover, we compared their FA proles with those from
other representative cnidarian orders (Rhizostomeae, Anthomedusae, Siphonophorae,
Alcyonacea, Scleractinia, Helioporacea and Pennatulacea). Velella velella and P. physalis
mainly differed in the presence of symbiotic dinoagellates markers (18:3n-6, 18:4n-3 and
20:5n-3 polyunsaturated FAs), present in higher percentage in the former, and bacterial
markers (odd-numbered, branched and 18:1n-7 FAs), which were more representative in
the latter. When comparing these species' FA proles with the ones of other cnidarians
orders, the presence/absence of endosymbionts and of specic FAs (tetracosapentaenoic
and tetracosahexaenoic acids) as well as the latitudinal habitats were the main drivers for
the distinction between groups.
©2016 Elsevier Ltd. All rights reserved.
1. Introduction
Lipids are important constituents of all marine organisms. They play a major role in energy storage and cell structuring
(Harland et al., 1993; Ward, 1995) and are deeply involved in several biochemical and physiological processes (Ward, 1995;
Rodrigues et al., 2008). Given the importance of lipids in organisms' functioning, the study of their main components efatty
acids (FAs) - is imperative when attempting to uncover species' ecological traits (Imbs et al., 2010; Baptista et al., 2012, 2014).
The FA prole of an organism is determined by environmental and biotic factors, including its synthesis ability which is
genetically inherited (Sargent and Whittle, 1981; Napolitano et al., 1997; Dalsgaard et al., 2003), feeding regime (Arts et al.,
*Corresponding author.
E-mail address: (M. Baptista).
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0305-1978/©2016 Elsevier Ltd. All rights reserved.
Biochemical Systematics and Ecology 66 (2016) 297e306
2001; Dalsgaard et al., 2003; Sara, 2009), environmental parameters (e.g. temperature (Oku et al., 2003; Imbs and Yakovleva,
2012)) and associated microbiome (e.g. zooxanthellae (Imbs et al., 2009, 2014)). Organisms are usually able to biosynthesize
saturated FAs (SFAs) and monounsaturated FAs (MUFAs) in levels that meet their requirements (Kaneda, 1991; Mortillaro
et al., 2009; Parrish, 2013). Nevertheless, photosynthetic symbionts such as zooxanthellae may also be an important
source of SFAs (Patton et al., 1983), while bacteria may be an important source of certain MUFAs, odd numbered and branched
FAs (Dalsgaard et al., 20 03). On the otherhand, biosynthesis of polyunsaturated FAs (PUFAs) is generally limited to a restricted
group of organisms (e.g. phytoplankton) (Drazen et al., 2008; Mortillaro et al., 2009; Sara, 2009) and the majority of animals
have to obtain them through dietary intake (Patton et al., 1983). This way, differences in environmental conditions could lead
to changes in the FA prole of an organism once distant locations could diverge in abiotic parameters such as temperature, as
well as in food sources availability (Freites et al., 2002, 2010).
By knowing the origin of specic FAs, these can be used as chemotaxonomic markers (Imbs et al., 2010). In fact, FAs have
been successfully used for the chemosystematics of different taxonomic groups (e.g. Volkman et al., 1998; Berg
e and
Barnathan, 2005; Imbs et al., 2007b) and are widely used as biomarkers in marine food-web studies (Dalsgaard et al.,
2003; Imbs and Dautova, 2008; Colaço et al., 2009).
Numerous studies have already described the FA prole of several cnidarian groups (e.g. Stillway, 1976; Imbs et al., 20 07b;
Morais et al., 2009). However, the large majority only focus in the class Anthozoa (e.g. Imbs et al., 2007b, 2010; Imbs and
Dautova, 2008). With only a few studies regarding the FA composition of hydrozoans (e.g. Stillway, 1976; Morais et al.,
2009; Mortillaro et al., 2009), and any of these addressing the chemotaxonomy of these organisms.
The Portuguese man-of-war [Physalia physalis (Linnaeus, 1758), family Siphonophora] and the wind sailor [Velella velella
(Linnaeus, 1758), family Anthoathecata] are two pleustonic siphonophoran hydrozoan species. Physalia physalis is an ubiq-
uitous species that inhabits tropical and subtropical waters (Purcell, 1984), while V. velella occurs in warm and temperate
waters (Purcell et al., 2012). Both species are carnivorous and important members of a specialized ocean surface community
(pleuston), being predated by several invertebrate and vertebrate species (Stillway, 1976). Following this, the knowledge on
the biochemistry of such ecologically relevant species is crucial. The present work describes the FA proles of P. physalis and V.
velella and establishes, for the rst, time the chemotaxonomic discrimination: i) between these two hydrozoans, and ii)
between these hydrozoans and other cnidarian groups.
2. Materials and methods
2.1. Biological sampling
Pleustonic hydrozoan colonies of Velella velella and Physalia physalis were hand collected in Cabo Raso, Cascais, mainland
Portugal (approx. 38.709882
N, 9.486837
W) and Praia de Porto Pim, Faial Island, Azores (approx. 38.523453
W), respectively. Sampling collection took place in April 2013, with the specimens reaching the shore driven by
onshore winds. Water temperature at sampling sites ranged between 15e17
C in Cascais and 17e18
C in the Azores (max
C; source: AVHRR SST averages for 8 day period, IMAR-DOP/UAç). Following collection, three pooled samples (six whole
colonies per pool) were vacuum packed and frozen at 80
C. For biochemical analyses, frozen samples were freeze-dried for
72 h at 50
C under low pressure (approximately 10
atm), powdered using a grinder (Retsch Grindomix GM200, Düs-
seldorf, Germany), and stored at 80
2.2. Fatty acid analyses
The determination of the FA prole was based on the experimental procedure previously described by Rosa et al. (2007)
and Baptista et al. (2012). Triplicate samples (300e330 mg of dry mass per sample) were dissolved in 5 mL of acetyl chloride/
methanol (1:19 v/v; Merck), shaken, and heated at 80
C for 1 h. After cooling, 1 mL of Milli-Q distilled water and 2 mL of n-
heptane pro-analysis (Merck) were added and samples were shaken and centrifuged (2300g, 5 min) until phase separation.
The moisture content of the upper phase was removed using anhydrous sodium sulfate (Panreac). An aliquot (2
l) of the
upper phase was injected onto a gas chromatograph (Varian Star 3800 Cp, Walnut Creek, CA, USA) equipped with an auto-
sampler and tted with a ame ionization detector at 250
C for fatty acid methyl ester (FAME) analysis. The separation was
carried out with helium as carrier gas at a ow rate of 1 mL min
in a capillary column DB-WAX (30 m length x 0.32 mm
internal diameter; 0.25
mlm thickness; Hewlett-Packard, Albertville, MN) programmed at 180
C for 5 min, raised to 220 at
C min
, and maintained at 220
C for 5 min with the injector at 250
C. FAME identication (% total FA) was accomplished
through comparison of retention times with those of Sigma, Nu Check Preap and Larodan Fine Chemicals standards.
2.3. Statistical Analysis
The percentage of individual FAs obtained for V. velella and P. physalis was tested for normality and homoscedasticity
(Kolmogorov-Smirnov and Levene's tests, respectively) and subsequently compared using t-test analyses.
In order to perform an intra-phylum analysis, the FA proles of 27 cnidarian species belonging to seven different orders:
Rhizostomeae (n ¼1), Anthomedusae (n ¼2), Siphonophorae (n ¼1), Alcyonacea (n ¼11), Scleractinia (n ¼10), Helioporacea
(n ¼1) and Pennatulacea (n ¼1), were compiled from available literature. Details on the species used in the intra-phylum
A.R. Lopes et al. / Biochemical Systematics and Ecology 66 (2016) 297e306298
analysis, including information on the presence of symbionts and number of specimens, are available in Table SI. Provided
that most authors solely focus on FAs representing 0.1% of total FA, the FAs exhibiting lower concentrations were not
considered in this analysis. A total of 26 FAs (14:0,15:0, 16:0, 17:0,18:0, Anteiso 16:0, Iso 17:0,16:1n-9, 16:1n-7, 18:1n-9, 18:1n-
7, 20:1n-9, 20:1n-7, 22:1n-11, 16:2n-4, 16:3n-3,18:2n-6, 18:4n-3, 20:3n-3, 20:4n-3, 20:5n-3, 22:5n-6, 22:5n-3, 22:6n-3, 24:5n-
6, 24:6n-3) were used in a principal component analysis (PCA). PCA reduces the number of dimensions produced by the large
number of variables and uses linear correlations (components) to identify those FAs that contributed most to the separation
between species (Quinn and Keough, 2002).
PCA was complemented with a multivariate analysis of variance (MANOVA) in order to identify signicant differences in
the variation of individual FAs percentage of colonies belonging to different taxonomical groups. The Wilks' lambda was
considered in this analysis. Organisms belonging to Helioporaceae, Rhizostomae and Scleractinia (symbiotic) were excluded
from the analysis of variance (n ¼1 for each specimen). As signicant differences between groups were found, one-way
ANOVA followed by multiple comparisons tests (Unequal N HSD), were performed to scrutinize the effect of the group on
each FA. The Dunn-Sidak procedure was used toadjust the associated signicance level of the family-wise type-I error (Quinn
and Keough, 2002). A total of 7 comparisons were applied (7 taxonomic groups), resulting in a signicance level of 0.007.
Unless stated otherwise, a signicance level of 0.05 was considered in the analyses. The software Statistica 12.0 (Statsoft,
Inc., Tulsa, OK 74104, USA) was used.
3. Results
3.1. Fatty acid composition of two open ocean pleustonic hydrozoans
Detailed FA proles of Velella velella and Physalia physalis are shown in Table 1.
The major saturated fatty acid (SFA) in both species was palmitic acid (16:0; 22% of total FA in P. physalis against 16% in V.
vellela;Table 1;t-test: P<0.001, Fig. 1) followed by stearic acid (18:0; 10% vs 5%; Table 1;t-test: P<0.001; Fig. 1). The SFAs
found in lower concentrations were 15:0 (1.3% in P. physalis vs 0.3% in V. velella;Table 1;t-test: P<0.001) and 17:0 (1.2% vs
0.4%; Table 1;t-test: P<0.001). Overall, P. physalis presented a signicantly higher percentage of SFAs than V. velella with a
value of approximately 41% (of total FA) in the former against 28% in the latter (Table 1;t-test: P<0.001).
Regarding monounsaturated fatty acids (MUFA), vaccenic acid (18:1n-9) dominated in V. velella (7.3%) which exhibited a
signicantly higher proportion than that found in P. physalis (4.9%; Table 1;t-test: P<0.05; Fig. 2). Conversely, paulinic acid
(20:1n-7) dominated in P. physalis (6%), being present in signicantly higher levels when compared to V. vellela (0.1%; Table 1;
t-test: P<0.001). No signicant differences were found between these two species regarding MUFA fraction (Table 1;t-test:
P>0.05). However, it should be noted that V. velella exhibited some MUFAs that were not present in P. physalis, namely
cetoleic (22:1n-11) and erucic (22:1n-9) acids (Table 1).
The major polyunsaturated fatty acid (PUFA) in both species was docosahexaenoic acid (DHA, 22:6n-3), followed by
eicosapentaenoic acid (EPA, 20:5n-3), both found in signicantly greater concentration in V. velella (Table 1;t-tests: P<0.05;
Fig. 3). Unlike what was observed in the SFA fraction, PUFA fraction content was signicantly greater in V. velella (Table 1;t-
test: P<0.05). It is worth noting that this species exhibited several PUFAs that were not observed in P. physalis, namely
hexadecatetraenoic (16:4n-3),
-Linolenic acid (GLA, 18:3n-6), octadecatrienoic (18:3n-4),
-linolenic (ALA, 18:3n-3) and
arachidonic (ARA, 20:4n-6) acids (Table 1).
As to n-3/n-6 ratio, no signicant differences between species were found, with values of 10.79% and 12%, for V. velella and
P.physalis, respectively (Table 1).
3.2. Intra-phylum variations in fatty acid composition
In order to ascertain FA composition differences among species examined in the present study (V. velella and P. physalis)
and other cnidarian species belonging to seven orders, a PCA based on 26 FAs was performed (Fig. 4).
A clear crosswise separation between temperate and tropical species was observed mainly along the rst principal
component (PC1; explaining 20% of the variance), with temperate species [V. velella (Anthoathecata V.), P. physalis
(Siphonophorae) and V. cynomorium (Pennatulaceae)] being placed to the left whilst tropical species were placed to the right
(dashed line in Fig. 4A). The FAs that contributed the most to the separation of V. velella and P. physalis from other cnidarians
were 16:2n-4, 22:6n-3 (see also Fig. 3B; Table SIII), 20:1n-9(Fig. 2E; Table SIII) and 22:1n-11. Furthermore, V. velella was
isolated due to a higher percentage of 20:1n-9(Figs. 2E and 4B; Table SIII) and 22:1n-11 (Fig 4B, Table SIII). On the other hand,
a high percentage of vaccenic (18:1n-7) (Figs. 2D and 4B; Table SIII), pentadecanoic (15:0), margaric (17:0), hexadecadienoic
(16:2n-4), eicosatrienoic (20:3n-3) and 20:1n-7 acids were responsible for the separation of P. physalis from other cnidarian
species (Fig. 4B, Table SIII).
A clear distinction between species with and without photosynthetic symbionts (PS) was achieved with a transversal
separation along the PC2 (explaining 19% of the variance), with symbiotic species being placed in a right-lowermost position
and the asymbiotic ones in a left-uppermost position (dotted line in Fig. 4A). This separation occurred mainly due to the
contribution of the FAs 17:0,15:0, anteiso 16:0, and iso 17:0 (Fig. 1B), together with 18:1n-7 (Figs. 2D and 4B; Table SIII) and
tetracosahexaenoic (THA, 24:6n-3) (Figs. 3D and 4B; Table SIII), generally present in high percentage in species without
photosynthetic symbionts (although not always statistically conrmed by analyses of variance). Conversely, the FAs 18:4n-3
A.R. Lopes et al. / Biochemical Systematics and Ecology 66 (2016) 297e306 299
(Fig. 4B), 18:2n-6 (Fig. 4B) and 22:6n-3 (Fig. 3B, Table SIII) were generally found in greater amount in symbiotic organisms,
also contributing to species separation (Fig. 4B).
In regard to tetracosapolyenoic acids [tetracosapentaenoic (TPA, 24:5n-6) and tetracosahexaenoic (THA, 24:6n-3)], it is
worth noting that 24:6n-3 was found in the subclass discomedusae representative (C. tagi) while absent in the subclass
hydroidolina representatives (P. physalia,V. velella and Millepora sp.; Fig. 3C, D; Table SI).
4. Discussion
4.1. Fatty acid differences of two pleustonic hydrozoans
Fatty acids (FAs) are useful qualitative markers that can be used to trace or conrm predator-prey relationships as well as
organisms' taxonomic position and presence/absence of symbionts (e.g. Dalsgaard et al., 2003; Imbs et al., 2007a, 2014).
Table 1
Fatty acid composition (% of total FA) of Velella velella and Physalia physalis.* Asterisks represent sig-
nicant differences between species.
Fatty acids Velella velella Physalia physalis
Satured (SFA)
11:0 0.01 ±0.03 0.03 ±0.02
14:0* 3.83 ±0.22 4.57 ±0.92
Iso 15:0* 0.33 ±0.03 0.23 ±0.04
15:0* 0.31 ±0.04 1.26 ±0.24
Anteiso 16:0 e0.15 ±0.03
16:0* 15.99 ±0.66 22.36 ±3.53
Iso 17:0 0.33 ±0.03 0.34 ±0.04
17:0* 0.37 ±0.03 1.22 ±0.10
18:0* 5.02 ±0.18 9.94 ±0.30
19:0* 0.38 ±0.02 0.29 ±0.02
20:0* 1.63 ±0.15 0.34 ±0.05
22:0 0.40 ±0.04 e
SBranched 0.66 ±0.02 0.72 ±0.11
SSFA* 28.58 ±1.08 40.73 ±5.05
Monounsaturated (MUFA)
16:1n-9 1.20 ±1.01 0.75 ±0.28
16:1n-7* 0.21 ±0.25 2.37 ±0.38
18:1n-9* 7.29 ±0.40 4.86 ±0.23
18:1n-7* 0.48 ±0.12 1.20 ±0.06
20:1n-9* 4.23 ±0.52 0.47 ±0.10
20:1n-7* 0.09 ±0.01 6.00 ±4.74
22:1n-11 0.89 ±0.04 e
22:1n-9 0.38 ±0.03 e
SMUFA 14.77 ±0.67 15.64 ±5.46
Polyunsaturated (PUFA)
16:2n-4* 0.26 ±0.04 1.26 ±0.15
16:3n-4* 0.27 ±0.05 0.34 ±0.04
16:3n-3* 2.62 ±0.33 0.86 ±0.04
16:4n-3 0.07 ±0.07 e
18:2n-6* 1.20 ±0.11 0.91 ±0.05
18:3n-6 0.11 ±0.02 e
18:3n-4 0.12 ±0.01 e
18:3n-3 0.98 ±0.09 e
18:4n-3* 3.81 ±0.14 2.07 ±0.05
20:2n-6* 0.42 ±0.02 0.21 ±0.02
20:4n-6 0.33 ±0.02 e
20:3n-3* 0.11 ±0.02 2.24 ±2.05
20:4n-3 0.68 ±0.05 0.67 ±0.05
20:5n-3* 7.77 ±0.61 6.46 ±0.55
21:5n-3 0.24 ±0.03 0.27 ±0.06
22:4n-6* 0.47 ±0.06 0.28 ±0.06
22:5n-6* 0.49 ±0.04 1.59 ±0.27
22:5n-3* 1.37 ±0.09 1.86 ±0.39
22:6n-3* 27.60 ±1.24 22.94 ±4.43
SPUFA* 48.92 ±1.84 41.95 ±7.22
Sn-332.74 ±15.00 37.36 ±7.12
Sn-63.01 ±0.13 2.99 ±0.30
n-3/n-610.79 ±4.78 12.43 ±1.25
DHA/EPA 3.57 ±0.28 3.53 ±0.38
A.R. Lopes et al. / Biochemical Systematics and Ecology 66 (2016) 297e306300
Nonetheless, they should be used with caution since they may be metabolized and transformed after its consumption
(Dalsgaard et al., 2003).
The present work describes the FA proles of V. velella and P. physalis and establishes a chemotaxonomic discrimination in
relation to other cnidarian taxonomic groups. When comparing V. velella and P. physalis, several differences in the FA
composition become apparent, providing insights into distinct life traits between these species. Velella velella exhibited
greater C18 PUFA proportion along with other PUFAs such as 20:5n-3 and 22:6n-3, which indicates the presence of photo-
synthetic symbionts. Indeed, while studying the distribution of FAs in reef building corals regarding their taxonomic position
and presence of photosynthetic symbionts, Imbs et al. (2010) identied
-linolenic acid (18:3n-6), stearidonic acid (18:4n-3),
20:5n-3 and 22:6n-3 as markers of zooxanthellae, especially the PUFAs 18:4n-3 and 22:6n-3 which are often dominant in
dinoagellates (Dalsgaard et al., 2003; Imbs et al., 2010). Although in the present study the presence/absence of symbiotic
dinoagellates was not assessed, other studies reported the presence of dinoagellates in association with V. velella colonies
from the Pacic ocean and Mediterranean sea (Banaszak et al., 1993; Trench, 1993; Gast and Caron, 1996) with any study
reporting zooxanthellae associated with P. physalis.
In addition to photosynthetic symbionts, the presence of bacteria may also be detected through the specic FAs, partic-
ularly large quantities of odd-numbered and branched FAs as well as 16:1n-7 and 18:1n-7 (Dalsgaard et al., 2003). The present
study shows that P. physalis has high proportion of 16:1n-7 and 18:1n-7 (considerably greater than those found in V. velella)as
Fig. 1. Major saturated fatty acids and respective fraction (SFA) prole of 7 cnidarian orders. Values are means (±SD). PSand wPSstand for photosynthetic
symbionts and without photosynthetic symbionts groups, respectively; Anthoathecata V.and Anthoathecata M.represent Vellela vellela and Millepora sp. (see
Statistical Analysis section for more details). Letters denote signicant differences between groups (Unequal N HSD post-hoc test).
A.R. Lopes et al. / Biochemical Systematics and Ecology 66 (2016) 297e306 301
well as of odd-numbered FAs (e.g. 15:0 and 17:0) thus indicating bacterial presence. As proposed by Imbs et al. (2007a),a
possible explanation for the higher percentages observed for those FAs in P. physalis is that they occur as an adaptive response
to the absence of symbiotic microalgae. A greater bacterial community living on and/or inside P. physalis, when comparing to
V. velella should, therefore, be responsible for the increase in FA percentages.
Signicantly higher percentage of 20:5n-3 and 22:6n-3 were found in V. velella when compared to P. physalis. This is
probably explained by exposure of these species to different temperature regimes (Purcell, 1984; Purcell et al., 2012). In fact,
membrane uidity is largely determined by the balance between saturated and unsaturated fatty acids which in turn is
affected by temperature (Holland, 1978; Beninger and Stephan, 1985; Ojea et al., 2004). According to previous studies, the
general trend is an increase in unsaturated FAs at lower temperatures and an increase in saturated FAs at higher temperatures
(especially in the phospholipid fraction; (Pazos et al., 1996; Hall et al., 2002)). This compositional adaptation of membrane
lipids - homeoviscous adaptation, helps maintaining the correct membrane uidity at the new conditions (Sinensky, 1974).
This way, greater levels of the PUFAs 20:5n-3 and 22:6n-3 in V. velella could be linked to homeoviscous adaptation since water
temperature was colder upon the stranding event of V. velella (Cascais,15e17
C) than that of P. physalis (Azores,17e18
C, max
C). Still, one should keep in mind that the present FA analyses refers to total FA proportion and not to the phospholipid
fraction alone. Another important factor that could help explain the differences in 20:5n-3 and 22:6n-3 levels in both species
is food intake (Dalsgaard et al., 2003). The most common preys of P. physalia are leptocephalus and sh larvae (Purcell, 1984),
both exhibiting a predominance of these FAs (Deibel et al., 2012). In accordance, the present study shows high levels of these
FAs, similarly to what has been previously reported in other studies (e.g. Stillway, 1976). Contrarily, the diet of V. velella is
mainly composed of harpacticoid copepods (Purcell et al., 2012), which exhibit high levels of 20:1n-9 and 22:1n-11 (Dalsgaard
et al., 2003). Accordingly, V. velella exhibited a greater percentage of these FAs in comparison to P. physalia.
Fig. 2. Major monounsaturated fatty acids and respective fraction (MUFA) prole of 7 cnidarian orders. Values are means (±SD). PSand wPSstand for
photosynthetic symbionts and without photosynthetic symbionts groups, respectively; Anthoathecata V.and Anthoathecata M.represent Vellela vellela and
Millepora sp. (see Statistical Analysis section for more details). Letters denote signicant differences between groups (Unequal N HSD post-hoc test).
A.R. Lopes et al. / Biochemical Systematics and Ecology 66 (2016) 297e306302
4.2. Intra-phylum differences in fatty acid composition
The PCA based on 26 FAs of 28 cnidarian species provided insights into the FA composition similarities/dissimilarities
among the phylum. Three major factors contributing to species separation were identied: (i) presence/absence of symbionts,
(ii) temperature prole of sampling region, and (iii) presence/absence of tetracosapolyenoic acids.
Differences between groups were mainly driven from the presence/quantity of dinoagellate and bacterial FA markers.
Species with photosynthetic symbionts (PS) were clearly separated from those not exhibiting PS, with the exception of
Scleractinia. Hence, a separation was obtained between the species belonging to Anthoathecata, Helioporacea and Scler-
actinia orders and those belonging to Rhizostomae, Siphonophorae and Pennatulacea orders presenting higher percentage of
C18 PUFAs (dinoagellate markers) (Dalsgaard et al., 2003). Moreover, in general, higher percentage of bacterial markers
(15:0, 17:0, Iso 17:0, Anteiso 16:0 and 18:1n-7) were found in species without PS (Dalsgaard et al., 2003) which conrms the
theory proposed by Imbs et al. (2007a) which states that bacterial presence occur as an adaptive response to the absence of
symbiotic microalgae.
Species inhabiting different latitudinal habitats such as temperate, sub-tropical and tropical, are exposed to distinct
temperature regimes which are known to affect FA proles (Holland, 1978; Beninger and Stephan, 1985; Ojea et al., 20 04). In
our study, species captured in temperate waters (belonging to Pennatulacea, Siphonophorae and Anthoathecata V. orders),
were shown to possess distinct FA prole than those from species captured in tropical waters (Anthoathecata M., Scleractinia,
Alcyonacea, and Helioporacea orders). Interestingly, C. tagi (Rhizostomae) while collected in Portuguese waters (Morais et al.,
2009), exhibited a similar FA prole with tropical species. This may be explained by the water temperature registered in
Portuguese waters by the time of these organisms' collection (approximately 23
C; Morais et al., 2009), which is similar to the
Fig. 3. Major polyunsaturated fatty acids, respective fraction (PUFA) and total fatty acid (total FA) prole of 7 cnidarian orders. Values are means (±SD). PSand
wPSstand for photosynthetic symbionts and without photosynthetic symbionts groups, respectively; Anthoathecata V.and Anthoathecata M.represent
Vellela vellela and Millepora sp. (see Statistical Analysis section for more details). Letters denote signicant differences between groups (Unequal N HSD post-hoc
A.R. Lopes et al. / Biochemical Systematics and Ecology 66 (2016) 297e306 303
average temperature in tropical waters. On the other hand, the temperature upon species' collection in Portuguese waters of
the other studies ranged between 15
C and 18
C(Baptista et al., 2012 and present study). The latitude-related separation of
species was determined by the occurrence of high proportions of 20:5n-3, 22:6n-3,16:3n-3, 16:1n-9, 20:1n-9 and 22:1n-11 in
V. cynomorium,V. velella and P. physalis. Some of these FAs, namely 20:5n-3 and 22:6n-3, can be recognised as an adaptation to
the low temperatures occurring in a temperate marine environment (Holland, 1978; Beninger and Stephan, 1985; Ojea et al.,
2004). Still, temperature variation with latitude is one among a group of factors possibly dictating the FA prole differences
observed between temperate and tropical species. The potential inuence of dietary items, genetic inherent ability to
Fig. 4. Principal component analysis (PCA) based on total fatty acid (FA) composition (26 FAs of 28 cnidarian species). A) Principal component plot; Broken and
dotted lines are only represented for visualization purposes and do not represent any data; PSand wPSstand for photosynthetic symbionts and without
photosynthetic symbionts groups, respectively; Anthoathecata V.and Anthoathecata M.represent Vellela vellela and Millepora sp. (see Statistical Analysis
section for more details); B) loading plot of FAs and their contribution to the spread along PC1 and PC2.
A.R. Lopes et al. / Biochemical Systematics and Ecology 66 (2016) 297e306304
synthesize FAs and life cycle stage, among others, should not be disregarded when analysing the FA proles of the afore-
mentioned species (Arts et al., 2001; Dalsgaard et al., 2003; Sara, 2009).
Several FAs can act as unique chemical markers of some taxonomic groups. The PUFAs 24:5n-6 and 24:6n-3, for example,
are considered chemotaxonomic markers of the subclass Octocorallia (e.g. Svetashev and Vysotskii, 1998; Imbs and Dautova,
2008; Baptista et al., 2012). In accordance, from all species analysed,only octocorals exhibit 24:5n-6 (at a concentration higher
than that of trace levels). However, 24:6n-3 was also found in the scyphozoan C. tagi and in a generally higher concentration
than in the octocorals reported herein, with the exception of the pennatulacean V. cynomorium. A similar result was found by
Nichols et al. (2003) in the pelagic jellysh Aurelia sp., where this unusual long-chain fatty acid constituted about 9.3% of total
fatty acid. Therefore, we conclude that the presence of 24:6n-3 alone is not a suitable chemotaxonomic marker of the subclass
This study gives an enormous contribution on the knowledge of the lipids biochemistry of hydrozoans. Moreover, it
supports the use of FA prole as chemotaxonomic biomarkers, not only for the distinction between V. vellela an P. physalis but
also between these species and other cnidarians.
Lopes A. R., Baptista, M. and Dionísio, G. were supported by PhD scholarships funded by the Fundaç~
ao para a Ci^
encia e
Tecnologia (QREN-POPH-Type 4.1 eAdvanced training, subsidized by the European Social Fund and national funds MEC).
Gomes-Pereira, J. was supported by the doctoral grant from the Regional Directorate for Education, Science and Culture, of the
Regional Government of the Azores (M3.1.2/F/062/2011). This work would not have been possible without the help of several
individuals who in one way or another contributed and extended their valuable assistance in the preparation of this study
mainly Luís Pires from DOP, Univ. of Azores.
Appendix A. Supplementary data
Supplementary data related to this article can be found at
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... Thus, such a high content of tetracosapolyenoic acids 24:6n-3 and 24:5n-6 may be a characteristic feature of octocorals of the family Plexauridae. These FAs have not been detected in hydrozoans (Lopes et al. 2016;Imbs et al. 2019). Lopes et al. (2016) have shown that the most abundant FAs in the hydrozoans Velella velella and Physalia physalis (Hydrozoa, Hydroidolina, Anthoathecata, Capitata) are PUFA 22:6n-3 and SFA 16:0. ...
... These FAs have not been detected in hydrozoans (Lopes et al. 2016;Imbs et al. 2019). Lopes et al. (2016) have shown that the most abundant FAs in the hydrozoans Velella velella and Physalia physalis (Hydrozoa, Hydroidolina, Anthoathecata, Capitata) are PUFA 22:6n-3 and SFA 16:0. Imbs et al. (2019) have reported that PUFA 22:6n-3 is the major FA in the hydrocorals Millepora platyphylla and M. dichotoma (Hydrozoa: Hydroidolina: Anthoathecata: Capitata). ...
Full-text available
Gorgonian corals form complex interactions with a wide range of microorganisms, which play a key role in maintaining health of the holobiont. To assess the influence that various members of the microbial community exert on the coral lipidome, we analyzed storage (triacylglycerols (TG) and monoalkyldiacylglycerols) and structural (phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine, phosphatidylinositol and lyso-phosphatidylcholine) lipid molecular species. A molecular-genetics analysis showed that colonies of Junceella fragilis were associated with Symbiodinium clade C. Sequences of the parasitic dinoflagellate Blastodinium contortum were found in the gorgonian Dichotella sp. Colonies of Astrogorgia rubra were associated with the filiferan hydroid Hydrichthella epigorgia. Fungal sequences were found in Dichotella sp., A. rubra and Menella sp. A molecular species of ether phospholipids with fungal hydroxylated fatty acids (FA), bacterial odd-numbered FAs and alkyl moiety were detected in gorgonian lipids. As both host coral and some bacteria can synthesize ether lipids, a conclusion was drawn that lipids are likely to be transported from members of the microbial community to the coral host, and some molecular species with an odd-numbered alkyl moiety can be derived from anaerobic bacteria. The TG content of the symbiotic gorgonian J. fragilis was 30-fold higher than in asymbiotic gorgonians. TG 18:3/18:4/18:3 can be considered as a marker of zooxanthellae presence in coral. The hydroid H. epigorgia association did not have any evident contribution to the lipid profile of gorgonian A. rubra. Such markers of soft corals as 24:6n-3 and 24:5n-6 PUFAs were found to be distributed in molecular species of lipids of all the studied corals. A high content of these acids was observed as a characteristic feature in corals of the family Plexauridae (Menella sp. and A. rubra). The lipidomic approach allows assessment of the distribution of marker fatty acids in coral lipids, and to tracing the relationships between the microbial community and the coral host.
... Indeed, FA are vital to coral metabolism and stress tolerance (Imbs et al. 2015). Moreover, FA profiles of different coral species have been used as chemotaxonomic biomarkers as they are suggested to be species-specific (Latyshev et al. 1991;Imbs et al. 2007Imbs et al. , 2010bImbs et al. , 2016Lopes et al. 2016). For example, octocorals can be identified by their synthesis of 24:5n-3 and 24:6n-6, as these FA are absent in hexacorals (Svetashev and Vysotskii 1998;Imbs et al. 2010a). ...
... For example, octocorals can be identified by their synthesis of 24:5n-3 and 24:6n-6, as these FA are absent in hexacorals (Svetashev and Vysotskii 1998;Imbs et al. 2010a). Symbiotic corals can be identified by high level of 18:3n-6 (GLA) and 18:4n-3 (SDA), as these FAs are present in symbiotic algae, while they are very low in non-symbiotic corals (Papina et al. 2003;Imbs et al. 2007Imbs et al. , 2010bImbs 2013;Lopes et al. 2016). Imbs et al. (2007) classified five different families (Acroporidae, Faviidae, Fungidae, Pocilloporidae, and Poritidae) of the scleractinian corals based on their specific polyunsaturated fatty acids (PUFAs), as they found that several FAs can only be detected in certain taxonomic groups of corals. ...
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Fatty acids (FAs) are the main components of lipids in corals. We examined FAs profiles from five symbiotic coral species belonging to five different genera (Acropora, Pavona, Turbinaria, Favites, and Platygyra) and four different families (Acroporidae, Agariciidae, Dendrophyllidae, Faviidae). We separated symbionts from the coral host tissue to investigate the interaction of FA between symbionts and host tissue. After separation, we used FA profiles, in particular specific FAs (e.g. 16:0, 18:0, 18:3n-3, 20:5n-3, 22:6n-3) and their ratios (EPA:DHA, PUFA:SFA) as biomarkers (i.e. signature lipids) to examine chemotaxonomy and trophic level (autotrophy vs. heterotrophy) of each coral species. Gas chromatography–mass spectrometry (GC–MS) was performed to identify and quantify FA. For quantification, the dry weight of total lipids was used to normalize FA concentration (μg mg⁻¹). We found that (1) the five different coral species showed define species-specific FA profiles; (2) certain FAs were valuable biomarkers to determine relative trophic strategies (i.e. autotrophy and/or heterotrophy; (3) the application of FA ratios to define trophic level requires caution in research application and data interpretation. Considering the limitations of FA ratios determined herein, we suggest it to be more appropriate to examine response to environmental change within species. Going forward, our study provides important FA baseline data that builds the foundation for future investigations on the impact of environmental changes related to nutrition and metabolism in symbiotic corals.
... FAs are the main constituent of lipids involved in most of the biochemical and physiological processes in living organisms (Imbs et al., 2007a). Some FAs such as PUFAs were used to classify the taxonomic grouping of cnidarians (Imbs et al., 2014;Imbs et al., 2007a;Lopes et al., 2016). For instance, the chemotaxonomic difference in the distribution of a very long-chain PUFAs (C 24 ) distinguishes Hexacorallia and Octocorallia from the Anthozoa class of cnidarian (Figueiredo et al., 2017;Imbs et al., 2010a). ...
Fatty Acids (FAs) are the biochemical compounds used as chemotaxonomic biomarkers for the systematic grouping of cnidarians. This study presents the chemotaxonomy of hard coral, particularly from the family Acroporidae (Anacropora [ANA], Montipora [MON], Astreopora [AST], and Acropora [ACP]) by applying multivariate analysis of FA composition matrix, of polyunsaturated FAs (PUFAs) to make a distinction among coral genera within the family. 18:4n-3, 18:3n-6, 20:5n-3, 20:4n-6, 22:6n-3, and 22:4n-6 have been identified as the characteristic FAs to differentiate between coral genera from the family Acroporidae. The classification of ANA, AST, and ACP was extensively affected by the distribution of the 18:4n-3, 20:5n-3, 22:6n-3, and 20:4n-6 FAs, while MON differed from the others with distinctive 22:4n-6 and 18:3n-6 compositions. The PUFAs 18:4n-3, 18:3n-6, and 20:5n-3 were then correlated with the Symbiodiniaceae (SYMD) density, thus rendering them a possible biomarker for symbiotic algae. The study findings indicate that genera-specific compositions can be characterised from the different PUFA content within the cnidarian through multivariate analyses such as permutational analysis of variance (PERMANOVA), similarity percentage (SIMPER), and canonical analysis of principal component (CAP). The FA composition and distribution are used for further classification of the hard corals to the lowest taxonomic level possible.
... In 2001, this species was reported in Maltese waters (Calleja, 2009). Other studies have indicated the presence of P. physalis in Malta in 2008, in summer 2009 and from March-June 2010 (Calleja, 2009;Deidun, 2010) The appearance of Physalia physalis in the Mediterranean is favoured by specific climatic and oceanographic conditions in the North Atlantic, which transport this jellyfish into the Mediterranean (Prieto et al., 2015;Lopes et al., 2016). These factors work together to push Atlantic colonies through the Strait of Gibraltar and into the Mediterranean basin. ...
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The pleustonic siphonophore Physalia physalis (Linnaeus, 1758) reported in the present study were collected in May 2018 on the north-western coast of Algeria. Two specimens of P. physalis have been observed, photographed and measured for the first time on the Al-Wardania beach, in Aïn Temouchent city. Their size is between 34.8 and 42 cm total length (TL). Morphometrics, meristics and diagnostic characteristics of the species are presented.
... Temperature is known to affect the FA profile of marine organisms, specifically due to lipids role in maintaining cell membrane integrity maintenance, and both palmitic acid and EPA are important for this task [89,92]. However, in the present study, we obtained different results from those already described in literature [93], as the proportion of unsaturated FA tend to increase at lower temperatures rather than at higher temperatures, in a process called homeoviscous adaptation that helps organisms to maintain the correct membrane fluidity at low temperatures. Nonetheless, the FA analysis in the present study refers to the total FA proportion in the two-spotted goby eggs and not only on the phospholipidic fraction. ...
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Climate change is a growing threat to marine organisms and ecosystems, and it is already modifying ocean properties by, for example, increasing temperature and decreasing pH. Increasing water temperature may also lead to an impairment of primary productivity and an overall depletion of available zooplankton. Understanding how the crossover between warming and zooplankton availability impacts fish populations has paramount implications for conservation and mitigation strategies. Through a cross factorial design to test the effects of ocean temperature and food availability in a temperate marine teleost, Pomatochistus flavescens, we showed that hindered feeding impacted sheltering and avoidance behaviour. Also, low food availability impaired fish reproduction, particularly male reproduction, as the expression of cyp11b1, a gene with a pivotal role in the synthesis of the most important fish androgen, 11-ketotestosterone, was significantly reduced under a low food regime. In contrast, temperature alone did not affect reproductive success, but offspring showed increased saturated fatty acid content (embryos) and increased lipid peroxidation (larvae). Altogether, food availability had a stronger effect on fitness, showing that coping with elevated temperatures, an ability that may be expected in shallow-water fish, can be indirectly impacted, or even overwhelmed, by the effects of ocean warming on primary productivity and downstream ecological processes.
... physalis (Lopes et al. 2016). These conditions combine to push this Atlantic species into the Mediterranean through the Strait of Gibraltar. ...
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Pelagic cnidarians have been observed stranding annually in the Tetouanise Sea, a site of intense human recreation in northwest Morocco. The abundance and size of jellyfish stranded, between January 2018 and December 2020, on the beaches of the Moroccan Mediterranean were investigated. We present data on the temporal and spatial distribution of the species in relation to environmental variables (e.g., sea surface temperature, salinity, chlorophyll and wind direction). We also examined the negative impacts of jellyfish on human activities in the Moroccan Mediterranean. Five species that represented three scyphozoans and two hydrozoans were frequently observed: Pelagia noctiluca, Velella velella, Physalia physalis, Rhizostoma pulmo and Chrysaora hysoscella. Three different models of seasonal occurrence of jellyfish were identified in this study: (1) P. noctiluca appears throughout the year but with a higher frequency during the summer, (2) P. physalis and V. velella appear in March–May and (3) the late appearing R. pulmo and C. hysoscella from July to August. The abundance of jellyfish varied from season to season, but did not differ between sampling sites. Interannual variations in the abundance of jellyfish were not significantly correlated with the environmental factors examined. However, the east wind played an important role in the stranding and formation of hotspots for jellyfish in the Moroccan coast. Continuous monitoring is needed for a more profound knowledge on the jellyfish bloom dynamics and their potential impacts on ecosystem functioning and socioeconomic activities in the Moroccan Mediterranean.
... Lipid, also considered as energy reserves (mainly refers to lipids and fatty acids (FAs) in this study), accounts for much of the coral body composition and is involved in a majority of physiological processes in corals (Conlan et al., 2017;Imbs et al., 2010). As FA composition is often species-specific, the FA profiles of different coral species have been used as valid chemotaxonomic indicators (Imbs et al., 2010;Lopes et al., 2016). Moreover, as certain FAs cannot be synthesized by marine consumers, FA profiles can be used as biomarkers to trace the nutritional input of corals (Mies et al., 2018). ...
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To meet the emerging demand of corals in various industries, it is necessary to develop an optimal technique to improve coral growth and health. Since heterotrophy provides a vital source of nutrients for corals, it is possible to implement a cultivation pattern combining regular methods with artificial feeding for corals. To this end, this study investigated the effects of feeding (supplemented with Artemia salina nauplii) on the production (growth and budding rate), body composition (tissue protein, crude lipid, and ash contents), and fatty acid profile (total fatty acid and polar lipid fatty acid profiles) of scleractinian coral Galaxea fascicularis in polyp morphology. Our results showed that feeding increased the production of G. fascicularis, with fed corals exhibiting a 51.4% higher growth rate and a double budding rate. Meanwhile, feeding changed the body composition of G. fascicularis, with increased tissue protein and crude lipid contents by 69.8%, and 31.0%, respectively, which indicated a good assimilation of supplementary proteins and lipids via feeding. Moreover, feeding also significantly changed the total FA profile of G. fascicularis, as it improved the levels of monounsaturated (MUFAs) and polyunsaturated fatty acids (PUFAs) (mainly n-3 PUFAs and n-6 PUFAs), but decreased the proportion of saturated fatty acids (SFAs) (mainly 16:0). However, there was no significant difference in the polar lipid FA composition of G. fascicularis between the two feeding regimes. This study highlights substantial improvements in the physiological state and health condition of corals under artificial feeding, and demonstrates that A. salina nauplii can serve as a suitable nutrient source for G. fascicularis in aquaculture.
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Physalia physalis and Velella velella , are among the few marine organisms that harness the wind for their locomotion, whereas other cnidarian jellyfish make use of their pulsating bell-shaped bodies to propel themselves through the seas. We investigate their composition and metabolism compared with two species of pulsating scyphozoan jellyfish, Aurelia aurita and Pelagia noctiluca . Protein (P), lipid (L), carbohydrate (K), and derived energy content (Ec), provided information on the biochemical composition of these species and their relevance as prey. Physiological respiration (R) from oxygen consumption. As well as potential respiration (Φ) from the electron transport system (ETS) activity and the derived respiratory carbon demand (RCD) and heterotrophic energy transformation (HET), allow the comparison of the impact of these two types of propulsion on the metabolism, along with the impact of these organisms as predators. In this study it was found that these hydrozoans depicted a different biochemical composition relative to other gelatinous zooplankton. Lower water content at around 90% was observed, while WM-specific P, L, K, and Ec were higher, showcasing new aspects of these species as prey. The lower R/P in P. physalis and V. velella (1.8 ± 0.7 and 2.9 ± 1.1 μL O 2 h –1 mg Prot –1 , respectively) and the low R/Φ, around 0.1, indicate lower respiration in wind-driven propulsion compared to pulsation-driven propulsion. Additionally, these results encourage the use and research on enzymatic techniques that are particularly useful for gelatinous research, and the calculation of RCD and HET helps in understanding the physiology and role played by the organisms as predators from carbon and energy perspectives.
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Legume seeds are known to be a source of protein, vitamins, essential organic minerals and fatty acids. Their high protein content makes them a valuable natural and inexpensive alternative to the soybean. Seeds fatty acids of genotypes belonging to nine Vicia L. taxa collected in Algeria were extracted by Soxhlet and their composition was determined by Gas Chromatography coupled with FIame Ionization Detection (GC-FID). In order to assess phylogenetic relationships between taxa on intra and interspecific levels, fatty acids profiles were used as a chemotaxonomic marker. Oil yields were between 0.67 and 2.40%. A total of 27 fatty acids were identified, varying from 9 to 20 compounds. The proportion of unsaturated fatty acids varies from 70.67 to 91.749% where the linloleic acid is predominant. While the saturated fatty acids content is between 8.60 and 29.33% with the predominance of palmitic acid. Our results demonstrate the quality of the genotypes, which contain fatty acids of great nutritional interests. Indeed, Omega 3- fatty acids, which rate can reach 12.187% in our taxa, are Poly UnSaturated Fatty Acids associated with many health benefits, such us cardiovascular ones. Indeed, the results demonstrate the nutritional quality of obtained oils and opens up perspectives to explore other compounds. Finally, the hierarchical classification revealed two major clusters where the taxonomic boundaries of the genus are well defined at subgeneric and sectional levels. It is also an important step to suggest the species as a new industrial crop for the animal feed and production of proteins and oils widely used in food industries
During recent years, the oceanic siphonophore Physalia physalis has repeatedly entered the Mediterranean Sea through the Strait of Gibraltar, being successively transported and distributed to different regions of that basin. When these floating colonies arrive to coastal areas during peak tourism periods there are large economic and health costs. Their highly venomous nature causes the closure of beaches and coastal attractions, creating a myriad of problems for local and regional authorities throughout the Mediterranean Sea. Many of these problems could be minimized or totally avoided if early warning of P. physalis arrivals to Mediterranean coasts could be issued. In this work, advanced particle tracking Lagrangian models were applied to simulate the dispersion and beaching of P. physalis colonies within the Mediterranean. Observations from two high-presence years (2010 and 2013) were used as calibration dataset and an additional high-abundance record (2018) was employed as validation for the models. The calibrated and validated model set-up was used to construct a statistical inference dataset and extraction tool (Physalia-SIM) that allowed assessing the likelihood of P. physalis arrival to any given coastal region of the Mediterranean Sea (with 97% accuracy) only by knowing their entrance time through the Strait of Gibraltar. The Physalia-SIM is a free-access, easily-useable tool by any stakeholder interested in knowing the probability for P. physalis presence in their particular region of interest. Moreover, this tool can help to provide warning as early as 3–4 months before the actual P. physalis presence is likely to occur. By making use of this prognosis tool, local and regional managers and stakeholders could take the necessary actions in order to minimize the economic and health impacts of the presence of these organisms in their coastlines.
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Few studies have been conducted on the temporal dynamics of both amino acid (AA) and fatty acid (FA) profiles in marine bivalves. We investigated the seasonal variation of these compounds in the pod razor clam Ensis siliqua in relation to food availability, salinity, water temperature and reproductive cycle. AA content varied between 46.94 and 54.67 % dry weight (DW), and the AAs found in greater quantity were glutamic acid, glycine and aspartic acid. FA content varied between 34.02 and 87.94 mg g−1 DW and the FAs found in greater quantity were 16:0 and 22:6n-3. Seasonal trends were observed for AAs and FAs. FAs increased with gametogenesis and decreased with spawning while AA content increased throughout spawning. The effect of increasing temperature and high food availability during the spawning season masked the loss of AAs resulting from gamete release. Still, a comparatively greater increase in the contents of glutamic acid and leucine with spawning indicate their possible involvement in a post-spawning gonad recovery mechanism. A post-spawning decrease in 14:0, 16:0, 16:1n-7, 18:1n-7 and 18:1n-9 is indicative of the importance of these FAs in bivalve eggs. An increase in 18:3n-3, 18:4n-3, 20:1n-9 and 20:2n-6 during gametogenesis suggests their involvement in oocyte maturation. The FA 22:4n-6, while increasing with spawning, appears to play a role in post-spawning gonad recovery. Salinity did not have an effect on the AA composition. None of the environmental parameters measured had an effect on FA composition.
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Coral bleaching induces changes in lipid and fatty acid composition that result in low lipid content, reducing the likelihood of coral survival. Species-specific differences in the metabolism of lipid reserves may contribute to the differential resistance of corals under acute heat exposures. Here, we examined the dynamics of lipids and fatty acid abundance in corals subjected to short-term heat stress. The stony corals Acropora intermedia, Montipora digitata, and the soft coral Sinularia capitalis all showed a 60–75% decline in both storage and structural lipids. However, S. capitalis and M. digitata exhibited no significant change in the percentages of structural lipids (i.e., polar lipids and sterols) until they had lost 90–95% of their endosymbionts, whereas A. intermedia showed a rapid decline in structural lipids after a 50% loss of symbionts. After a 90–95% loss of symbionts under heat stress, all three corals showed a relative depletion of polyunsaturated fatty acids that had symbiont biomarkers, suggesting that polyunsaturated fatty acids were translocated from the symbiont to the coral host tissue.
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The lipid class and fatty acid (FA) composition for 93 species of reef-building and soft corals from the South China Sea (Vietnam) were analyzed and statistically compared to study systematic patterns of the distribution of lipids in corals and the influence of zooxanthellae on the lipids of symbiont-host association. The lipid and FA compositions of hexacorals and octocorals significantly correlated with their taxonomic position, but the lipid features of species within each of these systematic groups mainly depended on the presence of zooxanthellae. The hexacorals had lower content of polar lipids (PL), sterols (ST), and monoalkyldiacylglycerols (MADAG), but higher content of triacylglycerols (TG) and wax esters (WE) than the octocorals. On average, zooxanthellate species contained less structural lipids (PL+ST), but more MADAG when compared to azooxanthellate species. Tetracosapolyenoic acids 24:5n-6 and 24:6n-3 were chemotaxonomic markers for octocorals, whereas 22:5n-6 was a marker for Milleporidae. A strong correlation was apparent between zooxanthellate coral family and/or genus and the content of the unsaturated FA; 12 FAs were significant for the separation of azooxanthellate and zooxanthellate specimens. The latter had lower concentrations of 7-Me-16:1n-10, 18:1n-7, and six C20-24 polyunsaturated FA, but higher concentrations of 16:0, 16:2n-7, 18:3n-6, and 18:4n-3. The presence of >2% of 18:3n-6 and 18:4n-3 of total FA is characteristic of zooxanthellate corals. An inverse correlation was established between the content of 18:3n-6 and 16:2n-7 in zooxanthellate soft corals. The present study highlights the importance of zooxanthellae in coral lipid metabolism, especially when compared with symbiont-host exchanges in reef-building and soft corals.
GLC investigation of FA composition of solar coral Heliopora coerulea (Helioporidae, Octacorallia) has revealed the presence of tetracosahexaenoic acid 24:6(n -3) in amounts about 2% of total fatty acids. Earlier, tetracosapolyenoic acids were detected in representatives of all other orders of the subclass Octacorallia: in Alcyonaria, Gorgonaria, and Pennatularia. Therefore, tetracosapolyenoic acids are characteristic for species relating to subclass Octacorallia. The other main fatty acids (over 1% of total fatty acid sum) of H. coerulea were, in descending order, 16:0, 18:3(n-6), 18:0, 20:5(n-3), 14:0, 22:6(n-3), 18:4(n-3), 16:1(n-7), 18:1 (n-9), 18:2(n-6), and phytanic.
Branching heads of symbiotic corals were pulse labeled with either 14C-acetate or 14C-bicarbonate for 1.33 h and the distribution and loss of label was then followed for 16d. The patterns of incorporation and washout were similar for both tracers. Non-solvent-extractable radioactivity (1/3 of the total) was divided into a CaCO3 and an organic fraction, both of which exhibited small if any decrease in radioactivity over 16d. In contrast, total solvent extractable (lipid) radioactivity (2/3 of the total) decreased during the washout period with the first half-life for bicarbonate at 2 d, the second at 4 d and the third could not be measured because of the persistence of a constant amount of radioactivity (18% of Day 1 value) from Day 8 to 16. Of the total retained activity, the zooxanthellae fraction contained between 8–18% from Day 1 to 5. The percentage of total animal (host) radioactivity in lipids rose from 35–40% at 0 time after tracer exposure to 70–90% at 60 min. The majority of 14C fixed into lipids was recovered in the fatty acyl moieties and not in the glycerol moiety as had been previously reported a number of times. These studies suggest that photosynthetically fixed carbon is immediately synthesized into lipid, which is translocated to the host. Analyses of the fatty acid compositions of triacylglycerols (TG) and wax esters (WE) of 40 species of coral from a small patch reef were made. In aposymbiotic species the absence of zooxanthellae appeared to be correlated with higher levels of total lipid, lower percentages of saturated fatty acids and lower TG/WE ratios than in species with symbionts.
Seasonal variations in the body weight and biochemical composition of the bivalve Ruditapes decussatus were studied over a period of 15 months. Separate analyses were made of foot, mantle edge, siphons, gills, adductor muscle and gonad-visceral mass. Variations in weight, body growth, gonad growth and spawning depended on environmental conditions, especially food availability. The gametogenic cycle comprised two phases: a resting phase (November–December) and gametogenesis, including ripeness and spawning, during the rest of the year. Gametogenesis usually took place during the spring, and spawning in summer (June–August). The highest variation in biochemical composition was largely attributable to a change in the glycogen content (average 14.7%±5.1 S.D. of dry weight). Protein (48.1%±1.8) and lipid contents (5.6%±0.6) remained relatively constant throughout the year. Adductor muscle, foot and siphons contained mainly proteins (67.8%, 51.2% and 65.8% of the dry tissue weight, respectively) and gonad-visceral mass and gills contained the highest amount of lipids (≈7%). The gonad-visceral mass showed the largest variations in all components during the gametogenic cycle. Lipid and glycogen concentrations in the gonad-visceral mass were inversely related: maximum concentrations of glycogen occurred during the resting phase or initial gametogenesis and corresponded with minimum concentrations of lipids, and minimum concentrations of glycogen occurred at maturity when lipids reached maximum concentrations. The gonad-visceral mass contained lower amounts of proteins (
In the present study fatty acid profiles of Mytilus galloprovincialis mussel seeds originating from two habitats with different environmental conditions (rocky shore and subtidal) were compared after transfer to the same environmental habitat (subtidal). The aim of the research was to investigate the influence of various environmental parameters on the relative percentage of fatty acids. The study was based in the Arosa Rı́a, Northwest Spain, between 27th November 1995 and 3rd July 1996. The location of the mussels suspended from the raft, the rope density (1.6 kg m−1) and cultivation depth (1.5–5.0 m) were common parameters for both mussel groups. Our results show that during the first 36 days of the experimental period the mussel origin participated significantly in the model explaining the variance of various fatty acids of physiological importance in marine bivalves, namely the acids 18:0, 16:1n−7, 18:1n−9, 18:1n−7, 18:2n−6, 18:3n−3, 18:4n−3, 20:2NMID1, 20:5n−3 and 22:6n−3. In addition, other environmental parameters related to food availability, such as the ratio chl-a/POM and TPM, only participated in the explanation of two and three of these acids, respectively. In contrast, 50 days into the experiment the mussel origin did not participate in the model of variance of the fatty acids studied, and the ratio chl-a/POM participated significantly in the model explaining the variance of 11 of the total (16) selected fatty acids studied. Moreover, the coefficients were only positive in the fatty acids of known energetic importance in marine bivalves, namely the acids 14:0, 16:1n−7, 18:1n−7, 20:5n−3 and the ratio PUFAs n−3/n−6. The influence that mussel origin and various environmental parameters could exercise on the variability of diverse fatty acids of both mussel groups is discussed.
The fatty acid compositions of phytoplankton and major primary consumers were analyzed during the development of seasonal algal blooms in the Bahía Blanca estuary, situated on the southern coast of the province of Buenos Aires (Argentina), and Trinity Bay, at Sunnyside, on the eastern coast of Newfoundland (Canada). Primary consumers in the Bahía Blanca estuary were zooplankton dominated by the calanoid copepod Acartia tonsa. At Sunnyside, the primary consumers were the sea scallop Placopecten magellanicus, an ecological and economical important benthic bivalve. The study shows that in spite of obvious differences between the two environments and the analytical approaches employed in each case, the analyses of fatty acid biomarkers can provide relevant ecological information. The fatty acid composition of the lipids of Bahía Blanca phytoplankton (high concentrations of the fatty acids 14:0, 16:4ω1, and 20:5ω3) reflected the presence of diatoms as a major component throughout the bloom. Fatty acid markers of the post-bloom phytoplankton in Bahía Blanca indicated a decline of phytoplankton biomass, and a relatively high input of detritus and terrestrial plant materials to the particulate organic matter of the estuary. Linoleic acid (18:2ω6), a typical “terrestrial” fatty acid, was conspicuous in the lipids of the post-bloom particulate matter of the Bahía Blanca estuary; 18:2ω2 was subsequently incorporated into zooplankton lipids diatom markers were also prominent in the lipids of pre-bloom and bloom phytoplankton at Sunnyside; post-bloom phytoplankton showed higher proportions of 18:0, 18:1ω9, and 18:4ω3, characteristic and often major fatty acids of dinoflagellates. The fatty acids of the digestive gland of P. magellanicus reflected the fatty acid composition of the phytoplankton, whereas those of the adductor muscle were practically unaffected by the composition of the food. This organ-specific response of an animal to the fatty acid composition of the diet is examined in terms of different applications of the fatty acid marker concept.