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Assessing the Contribution of Posidonia oceanica to Mediterranean Secondary Production Through Stable Isotope Analysis
No full textThe role of seagrasses in providing a complex habitat for marine organisms is globally documented;
however, few studies have investigated the trophic incorporation of endemic Mediterranean
Posidonia oceanica into marine food webs. Meadows of P. oceanica are declining due to climate change
and anthropogenic pressures, emphasising the need to determine its contribution in local trophic
dynamics. We investigated whether benthic marine invertebrate (BMI) and fish consumers assimilate
carbon directly from P. oceanica seagrass or other sources along the seagrass meadow margins in
Malta. We sampled and analysed the ?13C and ?15N isotope values of P. oceanica, particulate organic
matter (POM), macroalgae, 14 invertebrate taxa, and 10 fishes at three locations marginal to P. oceanica
seagrass meadows. Stable isotope ratios were significantly different between all taxa (F26 = 17.37,
R2 = 0.68, p < 0.01) and locations (F2 = 34.22, R2 = 0.10, p < 0.01). The source, invertebrate, and fishes
were enriched in both 13C and 15N at Bah? ar ic? -C? agh? aq relative to the other locations, L?Ah? rax and
Golden Bay, likely due to the increased effluent. Stable isotope mixing models were somewhat confounded
as POM and macroalgae had similar ?13C and ?15N values at each site, hampering efforts to
define the resource use of the sampled taxa. However, Posidonia oceanica made the lowest contribution
for both consumer groups at all locations, consistent with the results of other Mediterranean studies,
suggesting that P. oceanica does not contribute significantly to the diet of consumers at seagrass
meadow margins within Maltese waters
Effect of turbidity on fish morphology: A case study of swordtail, Xiphophurus helleri, during early ontogeny
No full textThis work is aimed to study the effect of turbidity on the swordtail?s body shape during
its early developmental stages. For this purpose, two treatments were designed as turbid and clear
water, each with three replicates for 60 days. The body shape data was extracted by digitizing 16
landmark points on 2D pictures to analysis using the geometric morphometric technique. The results
showed a significant difference between the two treatments in terms of body shape. Fish under turbid
conditions had shorter eye diameters, lower and shorter heads, more dorsal position snout, and deeper
caudal peduncles. The priorities in the new environment i.e. turbid water needs to be changed to
decrease the adverse effect of the resulting pressures of this environment and increase the survival
rate leading to increasing the ability of the developing fish to occupy a wider range of habitats
Effects of temperature and microbial disruption on juvenile kelp Ecklonia radiata and its associated bacterial community
No full textOcean warming can affect the development and physiological responses of
kelps, and under future climate change scenarios, increasing seawater
temperatures pose a major threat to these habitat-forming species. However,
little is known about the effects of warming on epiphytic bacterial communities
and how an altered microbiome may interact with temperature stress, affecting
the condition and survival of kelp, particularly of the potentially more vulnerable
early life stages. Here, we tested the effects of thermal stress on the growth and
physiological responses of juvenile kelp Ecklonia radiata in which their epiphytic
bacterial community was experimentally disrupted using antimicrobials,
simulating dysbiosis. We hypothesized that, under thermal stress (23?C,
simulating a extreme scenario of ocean warming in Tasmania), kelp with a
disrupted bacterial community would be more strongly affected than kelp with
an undisrupted microbiome or kelp under ambient temperature (14?C) but with a
disrupted microbiota. Thermal stress reduced growth, increased tissue bleaching
and negatively affected net photosynthesis of kelp. In addition, a substantial
change in the epiphytic bacterial community structure was also found under
thermal stress conditions, with an increase in the abundance of potentially
pathogenic bacterial groups. However, microbial disruption did not act
synergistically with thermal stress to affect kelp juveniles. These results suggest
that effects of elevated temperature on juvenile kelps is not microbially-mediated
and that juveniles may be less susceptible to disruptions of their microbiome
KAJIAN PERENCATAN KAKISAN MENGGUNAKAN KARBOKSIMETIL SELULOSA-CECAIR IONIK MELALUI TEKNIK ELEKTROKIMIA DAN PEMBELAJARAN MESIN
No full textEffects of Soybean Isoflavones on the Growth Performance and Lipid Metabolism of the Juvenile Chinese Mitten Crab Eriocheir sinensis
No full textIn order to study the effects of soybean isoflavones on the growth performance and lipid
metabolism of juvenile Chinese mitten crabs, six experimental diets were formulated by gradient
supplementation with 0%, 0.004% and 0.008% soybean isoflavones at different dietary lipid levels
(10% and 15%). The groups were named as follows: NF-0 group (10% fat and 0% SIFs), NF-0.004
group (10% fat and 0.004% SIFs), NF-0.008 group (10% fat and 0.008% SIFs), HF-0 group (15% fat and
0% SIFs), HF-0.004 group (15% fat and 0.004% SIFs) and HF-0.008 group (15% fat and 0.008% SIFs).
All crabs with an initial weight of 0.4 ? 0.03 g were fed for 8 weeks. The results showed that dietary
supplementation with 0.004% or 0.008% SIFs significantly increased the weight gain and specific
growth rate of crabs. Diets supplemented with 0.004% or 0.008% SIFs significantly reduced the
content of non-esterified free fatty acids and triglycerides in the hepatopancreas of crabs at the 10%
dietary lipid level. Dietary SIFs significantly decreased the relative mRNA expressions of elongase of
very-long-chain fatty acids 6 (elovl6), triglyceride lipase (tgl), sterol regulatory element-binding protein
1 (srebp-1), carnitine palmitoyltransferase-1a (cpt-1a), fatty acid transporter protein 4 (fatp4), carnitine
palmitoyltransferase-2 (cpt-2), ?9 fatty acyl desaturase (?9 fad), carnitine palmitoyltransferase-1b
(cpt-1b), fatty acid-binding protein 10 (fabp10) and microsomal triglyceride transfer protein (mttp)
in the hepatopancreas of crabs. At the 15% dietary lipid level, 0.008% SIFs significantly increased
the relative mRNA expressions of fatty acid-binding protein 3 (fabp3), carnitine acetyltransferase
(caat), fatp4, fabp10, tgl, cpt-1a, cpt-1b and cpt-2 and significantly down-regulated the relative mRNA
expressions of ?9 fad and srebp-1. In conclusion, SIFs can improve the growth and utilization of a
high-fat diet by inhibiting genes related to lipid synthesis and promoting lipid decomposition in
juvenile Chinese mitten crabs
PERMODELAN RAMALAN UNTUK PELEPASAN OKSIDA NITROGEN OLEH ENJIN DIESEL YANG DIKENDALIKAN DENGAN BAHAN API PLASTIK ALTERNATIF
No full textFeeding Behavior and Bait Selection Characteristics for the Portunidae Crabs Portunus sanguinolentus and Charybdis natator
No full textUnderstanding the feeding behavior of Portunidae crabs with different baits can improve
bait selection and is crucial for improving the effectiveness of crab fishing gear. This study, conducted
in indoor experimental tanks, used trajectory tracking software and two types of natural baits
(mackerel (Scomber australasicus) and squid (Uroteuthis chinensis)) to understand the behavior of
Portunus sanguinolentus and Charybdis natator. Spatial distribution results showed that P. sanguinolentus
was frequently present in the starting area (S1) and bait area (S3) in the control and treatment
groups. However, C. natator was frequently present and concentrated in the S1 area compared to
the middle areas S2 and S3, and only in the mackerel treatments were they observed to move to the
S3 areas. The spatial distribution results indicate that P. sanguinolentus shows a stronger willingness
to explore its surroundings, while C. natator is generally in a stationary, wait-and-see state. The
swimming speeds of P. sanguinolentus and C. natator showed different trends. P. sanguinolentus
showed continuous movement with no fixed speed when no bait was present in the control groups.
However, when treated with mackerel and squid, the average swimming speed of P. sanguinolentus
was faster (>5 cm/s) in the first 10 min and showed a more stable movement speed when searching
for the baits. C. natator showed a stationary or low movement speed when no bait was present in
the control groups. However, when C. natator perceived the presence of the baits in the treatment
groups, their movement speed increased in the first 10 min. In addition, there was no significant
difference between male and female crabs of P. sanguinolentus and C. natator in movement speed in
the control and treatment groups. Compared to C. natator, P. sanguinolentus might be more sensitive
to natural baits, as shown by its movement from S1 to S3. The results indicate that the species of
Portunidae crabs show different bait selections. Natural baits (mackerel and squid) are recommended
for catching P. sanguinolentus in crab fisheries
Oceanographic processes driving low-oxygen conditions inside Patagonian fjords
No full textThe dissolved oxygen (DO) levels of coastal ocean
waters have decreased over the last few decades in part because
of the increase in surface and subsurface water temperature
caused by climate change, the reduction in ocean ventilation,
and the increase in stratification and eutrophication.
In addition, biological and human activity in coastal zones,
bays, and estuaries has contributed to the acceleration of current
oxygen loss. The Patagonian fjord and channel system
is one world region where low-DO water (LDOW, 30 %?
60% oxygen saturation) and hypoxia conditions ( < 30%
oxygen saturation, 2mLL?1 or 89.2 ?mol L?1/ are observed.
An in situ dataset of hydrographic and biogeochemical variables
(1507 stations), collected from sporadic oceanographic
cruises between 1970 and 2021, was used to evaluate the
mechanisms involved in the presence of LDOWand hypoxic
conditions in northern Patagonian fjords. Results denoted areas
with LDOW and hypoxia coinciding with the accumulation
of inorganic nutrients and the presence of salty and
oxygen-poor Equatorial Subsurface Water mass. The role of
biological activity in oxygen reduction was evident in the
dominance of community respiration over gross primary production.
This study elucidates the physical and biogeochemical
processes contributing to hypoxia and LDOW in the
northern Patagonian fjords, highlighting the significance of
performing multidisciplinary research and combining observational
and modeling work. This approach underscores the importance of a holistic understanding of the subject, encompassing
both real-world observations and insights provided
by modeling techniques
BODY SHAPE VARIATIONS OF TANK GOBY Glossogobius giuris (Hamilton 1822) IN THREE DISTINCT WATER BODIES OF CENTRAL VIETNAM
No full textTank goby Glossogobius giuris is widely distributed across Vietnamese
rivers, estuaries, and lagoons, particularly in the central region where
this species plays a pivotal role as a high commercial source for local
communities. In this study, we employed landmark-based geometric
morphometrics to compare the morphometric variations among three
distinct populations of G. giuris inhabiting the Tam Giang Lagoon (Thua
Thien Hue Province), Nhat Le Estuary (Quang Binh Province), and Truong
Giang River (Quang Nam Province), Vietnam. The analysis, utilizing
Permutational Multivariate Analysis of Variance (PERMANOVA) with
Mahalanobis distances, revealed significant differences in the body shape
among the three populations (P < 0.001). Specifically, with respect to the
lateral side, the highest Mahalanobis distance was observed between
specimens from the Tam Giang and Nhat Le, followed by the Tam Giang
and Truong Giang River, with the lowest value found between the Nhat
Le and Truong Giang. A similar pattern was observed for the dorsal side.
Canonical variate analysis (CVA) illustrated three distinct groups with
statistical significance in all cases (P < 0.001) and the confusion matrix
showed a high corrected grouping rate of 88.5% for the lateral side and
82.8% for the dorsal side. These findings indicated notable variations in
the body shape of G. giuris among the three studied areas. Fish sampled
from the Tam Giang Lagoon exhibited a streamlined body shape, while
those from the Truong Giang River and Nhat Le Estuary displayed a deeper
body profile. The observed morphological differences among these fish
populations are likely attributed to phenotypic adaptations driven by
environmental factors and habitat distinctions. Importantly, this study
marks the first attempt to compare the body shape variations of G. giuris
in both freshwater and estuarine environments within central Vietnam,
utilizing a landmark-based geometric approach. These findings provide
crucial insights for further investigations into the ecological adaptations
and evolutionary processes of this fish species
Cloning, Characterization and Functional Analysis of Caspase 8-like Gene in Apoptosis of Crassostrea hongkongensis Response to Hyper-Salinity Stress
No full textCaspase-8, a member of the caspase family, is an initiating caspase and plays a crucial
role in apoptosis. In this study, the full-length cDNA of caspase8-like (CASP8-like) was isolated from
Crassostrea hongkongensis (C. hongkongensis) by RACE-PCR. ChCASP8-like contained a 1599-bp open
reading frame (ORF) encoding 533 amino acids with two conserved death effector domains (DEDs)
and a cysteine aspartase cysteine structural domain (CASc). Amino acid sequence comparison showed
that ChCASP8-like shared the highest identity (85.4%) with CASP8-like of C. angulata. The tissue
expression profile showed that ChCASP8-like was constitutively expressed in gills, hepatopancreas,
mantle, adductor muscle, hemocytes and gonads, and was significantly upregulated in hemocytes,
hepatopancreas and gills under hyper-salinity stress. The apoptosis-related genes, including ATR,
CHK1, BCL-XL, CASP8-like, CASP9 and CASP3, were significantly activated by hyper-salinity stress,
but were remarkably inhibited by ChCASP8-like silencing. The caspase 8 activity was increased by
1.7-fold after hyper-salinity stress, and was inhibited by 9.4% by ChCASP8-like silencing. Moreover,
ChCASP8-like silencing clearly alleviated the apoptosis resulting from hyper-salinity stress. These
results collectively demonstrated that ChCASP8-like played a crucial role in inducing apoptosis
against hyper-salinity stress