Interspecific differences in the post-settlement survival of <Emphasis Type="Italic">Acropora</Emphasis> corals under a common garden experiment

Extremely low post-settlement survival is one of the largest barriers for artificial rehabilitation of Acropora corals. However, little data have been found for interspecific difference of the post-settlement survival probably because the observation of coral juvenile is difficult in the field. Here, we analyzed the survival of three dominant species of Acropora corals (A. digitifera, A. tenuis, A. yongei), with different colony morphologies and habitat preferences, for 2 years after settlement under the same environmental conditions. The post-settlement survival was significantly higher for A. tenuis than for A. digitifera 3 months after settlement. Two years later, the survival rate of A. tenuis was approximately 15 times higher than A. digitifera. In a separate analysis of three bottle-brush species (A. awi, A. echinata, A. subglabra) and A. tenuis, post-settlement survival was always higher for A. awi than for other two bottle-brush species, suggesting that the initial survival was different among morphologically sister species. Low survival was possibly associated with slow growth rates during the first 7 months. Thus, species selection is important for successful artificial coral rehabilitation, with A. tenuis being the most viable option. Alternatively, new techniques are required to improve post-settlement survival of slow growing coral species.     

Long-term fluctuations in mollusk populations before and after the appearance of the alien predator <Emphasis Type="Italic">Euspira fortunei</Emphasis> on the Tona coast,Miyagi Prefecture,northern Japan

The impact of Euspira fortunei as an alien predator on fluctuations in population densities of prey mollusks between 2001 and 2010 on the Tona coast, northern Japan, was investigated. This species increased dramatically from 2002 to 2004. In contrast, prey species such as Ruditapes philippinarum and Macoma incongrua decreased rapidly from 2001 to 2004, whereas Pillucina pisidium and Batillaria cumingii did not show a significant decrease during this period. Using a laboratory experiment, we were able to show that these decreases in the population densities of some species of mollusks but not other species were the result of species-selective predation by E. fortunei, as the experiment revealed that E. fortunei preferred to attack R. philippinarum and M. incongrua rather than P. pisidium, although the predator did expand its diet to include P. pisidium after it had consumed 16 of the 20 preferred prey available (i.e., R. philippinarum and M. incongrua). This case study suggests that invasive naticid predators have the potential to affect the population density and community structure of prey mollusks in recipient coastal ecosystems through predation.     

Molecular cloning and characterization of an inhibitor of apoptosis protein in the mud crab <Emphasis Type="Italic">Scylla paramamosain</Emphasis>: its potential anti-apoptosis role under air exposure stress

The mud crab Scylla paramamosain is a widely farmed commercial species in southeast coastal areas of China. The crabs are placed in water-free containers for transportation to inland markets, thus are exposed to dry conditions for more than 72 h after capture and may suffer from air exposure stress, triggering cell apoptosis leading to death. To evaluate whether an inhibitor of apoptosis protein (IAP) is involved in apoptosis resistance against air exposure stress in crustaceans, SpIAP was cloned and investigated for the first time. The full length of SpIAP was 3351 bp, encoding a polypeptide of 662 amino acids. The predicted SpIAP protein contained three baculoviral IAP repeat domains and one really interesting new gene (RING) finger domain. Protein basic local alignment search tool and phylogenetic analysis results showed that SpIAP was clustered together with other crustaceans IAPs. SpIAP was detected in all the examined tissues and predominantly expressed in the hepatopancreas. When crabs were challenged with air exposure for 12 h, the expression level of SpIAP in the hepatopancreas was significantly increased in the experimental group compared with the control group. A RNA interference assay and flow cytometry analysis showed that when SpIAP was silenced, the cell apoptotic rate significantly increased after 24 h air exposure. These results suggested that SpIAP was involved in an anti-apoptosis response induced by air exposure in S. paramamosain.     

Natural habitat contributes more to estuarine fish production than artificial habitat: an example from inter-river comparison in the Ohta River estuaries

Production of juvenile sea bass Lateolabrax japonicus cohorts during the period of post-migration into the Ohta River was compared between a drainage channel (DC) and a natural river (NR) in Hiroshima, southwestern Japan. Freshwater discharge during periods of high precipitation through the DC is controlled to minimize discharge into other rivers which run through the urban area. Juveniles in the DC had been expected to be affected by stronger disturbance in physical properties to their habitat due to higher fluctuations of freshwater discharge. In order to test this hypothesis, cohort-specific growth (G, d^?1) and mortality (M, d^?1) coefficients and the ratio of G to M (G/M as a proxy of juvenile production) were compared between the two rivers. Juvenile vital rates were estimated through (1) repeated sampling at fine time intervals (6–15 days), (2) application of otolith daily increments for cohort identification, and (3) standardization of abundance at age based on the length-dependent catch efficiency of the sampling gear to estimate M more accurately. G (0.012–0.021) did not significantly differ between the DC and NR. M in the DC (0.184–0.239) was significantly higher than in the NR (0.140–0.148) and average ratio of G/M (0.111) in the NR was higher than in the DC (0.082). High mortality due to physical processes (high variability in salinity) was concluded to contribute to the inter-river difference in juvenile production since the differences in prey availability, and vulnerability to predation between the two rivers were minimal.     

Importance of outer reef slopes for commercially important fishes: implications for designing a marine protected area in the Philippines

A passive acoustic telemetry survey was conducted to determine occurrence patterns of commercially important fishes on a steep reef slope along a marine protected area (MPA) in the southern Philippines, where the outer reef edge is often set as an offshore MPA boundary. Based on 4–61 days of tracking data from 21 detected individuals of five species (Lutjanus argentimaculatus, Lutjanus monostigma, Lethrinus atkinsoni, Lethrinus obsoletus, and Siganus guttatus; 20.7–69.2 cm fork length) caught near the reef slope of the MPA, S. guttatus occurred most frequently on the reef flat of the MPA, whereas all individuals of the four lutjanid and lethrinid species were primarily (99.4–100%) detected near the reef slope, and nine individuals (56.3% of these four species) of three of these species (not L. obsoletus) most likely used the shallow (≤10 m) and deep (≥20 m) layers, and thus, middle layers of the slope. These findings indicate that commercially important lutjanid and lethrinid species predominantly and vertically used the areas near the reef slope, suggesting the importance of fully including reef slopes in MPAs to enhance their effectiveness for the conservation of such fishes.     

Cryptic occurrence of <Emphasis Type="Italic">Chattonella marina</Emphasis> var. <Emphasis Type="Italic">marina</Emphasis> in mangrove sediments in Probolinggo,East Java Province,Indonesia

Mangrove forests and adjacent creeks are known to be highly productive estuaries, which are partly supported by benthic microalgae that grow on the sediments. During surveys investigating the microalgal floras of mangrove swamps in the eastern part of Java Island, a mud sample unexpectedly included large numbers of a notorious fish killer, Chattonella-like motile cells, and its resting cysts. These motile cells were established as clonal cultures for further identification and physiological tests. The cysts were examined through palynological and molecular biological means. Identification based on light microscopy and ribosomal RNA gene sequences confirmed that these cells and cysts were Chattonella marina var. marina. While the strains were genetically identical to the temperate strains isolated from Japan and China, temperature experiments showed that the Indonesian strains possessed a high maximum quantum yield of photosystem II even after exposure to 34 °C, a temperature at which the Japanese strain could not survive. Salinity experiments showed adaptation of the strains to a salinity of 15. These findings, together with the discovery of populations of cysts in the mangrove sediment, highlight the tough and unique nature of the Indonesian strains, which are likely adapted to wide fluctuations of temperature and salinity in mangrove swamps, and pose a potential risk to fisheries in Indonesia.     

Spatial–temporal variations in the composition of two <Emphasis Type="Italic">Zostera</Emphasis> species in a seagrass bed: implications for population management of a commercially exploited grass shrimp

We examined spatial and temporal variations in the species composition of two seagrass species, Zostera marina and Z. caespitosa, in a lagoon facing the Sea of Okhotsk. We also considered how those variations affected habitat quality for motile epifauna, especially for a commercial shrimp. A long-interval comparison between 1996 and 2013 showed that seagrass species composition in the lagoon did not vary, while their relative abundances did. A survey in 2012 revealed that the abundance of Z. caespitosa was affected by the abundance of Z. marina, water depth, and location in the lagoon. Although these seagrass species have similar aboveground morphology, differences in their fine structures were detected. Diversities of motile animals inhabiting the seagrass species were the same. Differences in seagrass utilization were observed when we focused on a commercial shrimp, Pandalus latirostris. This shrimp always preferred higher densities of shoots irrespective of the species and seasonally changed their preference for the number of leaves per shoot. They were therefore more abundant in Z. caespitosa, which had those structural characteristics. The results suggest that the management of shrimp resources could be improved by flexibly changing protected areas in accordance with the dynamics of seagrass distribution in the lagoon.     

Microbial community in a multi-trophic aquaculture system of <Emphasis Type="Italic">Apostichopus japonicus</Emphasis>, <Emphasis Type="Italic">Styela clava</Emphasis> and microalgae

An integrated multi-trophic aquaculture (IMTA) system consisting of the ascidian Styela clava and the sea cucumber Apostichopus japonicus with microalgae was grown in a seawater mesocosm. Microbial populations in the water, sediment and shelters were monitored over time. The composition of the water microbial community in the IMTA system did not differ significantly from that of the traditional culture system without ascidians. Bacterial populations in the water, sediment and shelters were low in the traditional A. japonicus aquaculture system, and lower in the IMTA system. The number of Vibrios in the water, sediment and shelters in the IMTA system was significantly lower than in the traditional culture (p < 0.05), while the quantity of Bacillus was higher in the sediment and shelters. All of these results indicate that the IMTA system effectively inhibited the growth of harmful bacteria, an important positive function in the health of the culture. The bacterial diversity index in the water in the IMTA system was between those of the baited and non-baited traditional aquacultures and was slightly reduced in the shelters. Over time, the bacterial diversity index in the sediment gradually dropped, especially in summer and autumn, when it was significantly lower than in the traditional culture. In winter, the diversity index increased to some extent, approaching that of the traditional culture.     

Beak identification of four dominant octopus species in the East China Sea based on traditional measurements and geometric morphometrics

Octopus is the most abundant genus in the family Octopodidae and accounts for more than half of the total cephalopod landing in neritic fisheries. A taxonomic problem still exists due to synonymous scientific names and limited genetic information. The cephalopod beak is a stable structure that allows an effective solution to the problem of the species and stock identification. Beak shape variation has been more widely considered than beak measurements in recent years. In this study, with the beak as the experimental material, we combined geometric morphometrics (GM) with machine learning methods and compared the discrimination results obtained by traditional and GM methods in four Chinese neritic octopus species (Amphioctopus fangsiao, Amphioctopus ovulum, Octopus minor and Octopus sinensis). According to our analyses, Octopus sinensis has the larger beak size [both upper beak (UB) and lower beak (LB)] than other species. The results of ANOVA showed that all beak measurements differed significantly among the four species. Significant differences in both UB and LB shapes among four species were identified in MANOVA analysis based on the GM method. The results of GM-based discriminant analysis were better than those of traditional measurements, and machine learning methods also showed the higher correct classification rates than linear discriminant analysis. GM is a useful method to reconstruct the shape cephalopod beak and can also effectively distinguish different species. We should improve classification accuracy with machine learning methods for determining species structure in the future.     

Effects of starvation and feeding on blood chemistry,fatty acid composition and expression of vitellogenin and fatty acid-binding protein genes in female swimming crab <Emphasis Type="Italic">Portunus trituberculatus</Emphasis> broodstock

Portunus trituberculatus broodstock were stocked in plastic tanks to evaluate the effects of starvation and feeding on gonadal development, blood chemistry, fatty acid composition, and expression of vitellogenin (Vtg) and fatty acid-binding protein genes (FABP) in females. Two treatments (starved and fed) were randomly assigned to triplicate groups of 90 swimming crab broodstock (approximately 230 ± 45 g). In the starved treatment, crabs were starved for 30 days, whereas in the fed treatment crabs were fed once a day with clams. The gonadosomatic index decreased significantly in starved crabs (P < 0.05), as did the serum glucose and cholesterol concentrations; conversely, the total protein concentration in serum significantly increased (P < 0.05). In the ovary, there was a significant relative decline of 18:0, 16:1n-7 and 20:1n-9 fatty acids and relative increases of 20:4n-6, 22:6n-3, 18:1n-9 and 20:5n-3 in starved crabs compared to fed crabs (P < 0.05). Relative expression of Vtg in the ovary decreased significantly in starved crabs (P < 0.05), while there was no significant difference in hepatopancreas Vtg expression between starved and fed crabs (P > 0.05). Starvation suppressed gonadal development in female swimming crab broodstock.     

Impact of food type on growth,survival and reproduction of the cyclopoid copepod <Emphasis Type="Italic">Cyclopina kasignete</Emphasis> as a potential live food in aquaculture

This study compared the efficacy of different dietary algae on the growth and reproduction of the cyclopoid copepod Cyclopina kasignete, a potential live food species for fish larvae in aquaculture. The experimental diets for the copepod consisted of three monoalgal diets (Nannochloropsis oculata, Tisochrysis lutea and dry Melosira sp.) and two mixed algae diets (T. lutea?+?N. oculata, T. lutea?+?dry Melosira sp.). The experiment was carried out for 30 days, and the population growth, survival and reproductive performance (generation time, hatching rate, life spawning times, daily offspring production, eggs per sac, lifespan and sex ratio) were used to assess the responses of C. kasignete to different food types. Population growth, survival and reproductive capacities of C. kasignete were significantly affected by the mono and binary species of algal diets. The results showed that copepods exhibited superior growth, survival and productivity when fed on fresh T. lutea, dry Melosira sp. and a mixture of both species compared to other dietary treatments. Copepods produced comparable growth, survival and productivity when fed on diatoms (dry Melosira sp.) as a single or in combination with other algae. This study indicates that cyclopoid copepod C. kasignete grow fast and have the potential to serve as a live food for aquaculture. The algae T. lutea, dry Melosira sp. and their combination are appropriate food to sustain the growth and reproduction of this copepods in mass culture as a potential live food in fish hatchery.     

Characterization of a low-density lipoprotein receptor,Lrp13, in Chinese tongue sole (<Emphasis Type="Italic">Cynoglossus semilaevis</Emphasis>) and medaka (<Emphasis Type="Italic">Oryzias latipes</Emphasis>)

As an important economic marine species cultured in China, Chinese tongue sole (Cynoglossus semilaevis) has interested us due to its sexual dimorphism and ZW/ZZ sex determination system. In a previous study, dmrt1 was identified as a dosage-dependent male-determining gene. In the present study, a female-specific expressed gene, cse0440, initially annotated as lrp1b-like, was identified from chromosome W of C. semilaevis. In view of the differences between cse0440 and lrp1b in terms of expression pattern, a phylogenetic analysis containing 85 LRP proteins was constructed and provided an evidence to re-annotate cse0440 as cseLRP13. In addition, two orthologues of cseLRP13 were separately identified from W and Z chromosomes: cseLRP13-W and cseLRP13-Z. The subsequent multiple sequence alignment and syntenic arrangements of LRP13 in C. semilaevis, Japanese medaka (Oryzias latipes), large yellow croaker (Larimichthys crocea), striped bass (Morone saxatilis), white perch (Morone americana) and Fugu rubripes (Takifugu rubripes) further supported this re-annotation. RT-PCR and in situ hybridization revealed that cselrp13 was exclusively expressed in the oocytes and follicles of ovaries. These results suggested that lrp13 may play important roles in female reproduction. In future, with the advancement of micromanipulation in flatfish, the detailed function of two lrp13 orthologues in C. semilaevis will be elucidated.     

Effect of growth hormone overexpression on gastric evacuation rate in coho salmon

Growth hormone (GH) transgenic (T) coho salmon consistently show remarkably enhanced growth associated with increased appetite and food consumption compared to non-transgenic wild-type (NT) coho salmon. To improve understanding of the mechanism by which GH overexpression mediates food intake and digestion in T fish, feed intake and gastric evacuation rate (over 7 days) were measured in size-matched T and NT coho salmon. T fish displayed greatly enhanced feed intake levels (~ 2.5-fold), and more than 3-fold increase in gastric evacuation rates relative to NT coho salmon. Despite the differences in feed intake, no differences were noted in the time taken from first ingestion of food to stomach evacuation between genotypes. These results indicate that enhanced feed intake is coupled with an overall increased processing rate to enhance energy intake by T fish. To further investigate the molecular basis of these responses, we examined the messenger RNA (mRNA) levels of several genes in appetite- and gastric-regulation pathways (Agrp1, Bbs, Cart, Cck, Glp, Ghrelin, Grp, Leptin, Mc4r, Npy, and Pomc) by qPCR analyses in the brain (hypothalamus, preoptic area) and pituitary, and in peripheral tissues associated with digestion (liver, stomach, intestine, and adipose tissue). Significant increases in mRNA levels were found for Agrp1 in the preoptic area (POA) of the brain, and Grp and Pomc in pituitary for T coho salmon relative to NT. Mch and Npy showed significantly lower mRNA levels than NT fish in all brain tissues examined across all time-points after feeding. Mc4r and Cart for T showed significantly lower mRNA levels than NT in the POA and hypothalamus, respectively. In the case of peripheral tissues, T fish had lower mRNA levels of Glp and Leptin than NT fish in the intestine and adipose tissue, respectively. Grp, Cck, Bbs, Glp, and Leptin in stomach, adipose tissue, and/or intestine showed significant differences across the time-points after feeding, but Ghrelin showed no significant difference between T and NT fish in all tested tissues.     

Food habits of fishes in a freshwater reed belt in Lake Kitaura,eastern Japan,in summer

The diets and feeding guild structure of a freshwater reed belt fish assemblage (30 species) were examined in Lake Kitaura, part of the Lake Kasumigaura system, eastern Japan, from June to September in 2009 and 2010. Ontogenetic dietary shifts were recognized in 14 species, including several species (e.g., Cyprinus carpio, Tridentiger brevispinis and Hyporhamphus intermedius) targeted by local fisheries. Juveniles of these species generally fed on zooplankton, later switching to other prey items (e.g., benthic chironomid larvae, gammaridean amphipods, shrimps, juvenile fishes, diatoms and decomposing reeds) with growth. A cluster analysis based on dietary overlaps showed that the reed belt fish assemblage comprised five feeding guilds (plant, zooplankton, benthic invertebrate, terrestrial insect and fish feeders). Of these, zooplankton feeders were the most abundantly represented in terms of species numbers, suggesting that the main food items for the fish assemblage were zooplankton (e.g., cladocerans, and calanoid and cyclopoid copepods). Fish feeders included five species, of which one was an alien species introduced from another region in Japan (Opsariichthys uncirostris) and three were from foreign countries (Micropterus salmoides, Lepomis macrochirus macrochirus and Ictalurus punctatus).     

Characterization and expression of <Emphasis Type="Italic">lin-28a</Emphasis> involved in <Emphasis Type="Italic">lin28/let-7</Emphasis>signal pathway during early development of <Emphasis Type="Italic">P. olivaceus</Emphasis>

Heterochronic lin-28 is a conserved RNA-binding protein that plays a key role in the timing of developmental events in organisms. As a crucial heterochronic gene, the protein controls developmental events of the second of four larval stages in Caenorhabditi elegans. Heterochronic let-7 miRNAs are often present in various species and highly conserved in sequence and biological function and are required for various biological processes. Previous studies showed that ten let-7 miRNAs were identified in the Japanese flounder (Paralichthys olivaceus) and that they were primarily expressed during metamorphosis. In this study, we clone and characterize the lin-28a gene from P. olivaceus and exhibit its dynamic expression pattern at different developmental stages and various adult tissues. The results show that the P. olivaceus lin-28a gene has high sequence similarity with other species and is highly expressed in the embryonic stage but weakly expressed in the larval stage. In addition, lin-28a overexpression causes cell proliferation and significantly promotes the levels of pre-let-7a and pre-let-7d while markedly depressing let-7a and let-7d expression in FEC (Flounder Embryonic Cell), which indicate that lin-28 possibly blocks the maturation of let-7 miRNAs. Additionally, lin-28a is identified as a target gene of let-7 miRNAs, and let-7 miRNAs directly regulate lin-28a expression by targeting its 3′ UTR. Taken together, lin-28a along with let-7 miRNA participates in a lin-28/let-7 axis pathway that regulates cell division and timing of embryonic and metamorphic events in P. olivaceus.     

Zooplankton diversity of a protected and vulnerable wetland system in southern South America (Llancanelo area,Argentina)

In arid regions, climatic conditions exert a great control on the aquatic systems present, but recent changes in climate have produced an enhanced salinization of the aquatic environments located there. Consequently, a major reduction in biodiversity would be expected in those wetlands that were originally fresh water. Salinity is a principal cause of reduced biodiversity particularly in zooplankton because few of those species can adapt to the salt pressure of saline environments. Therefore, the aim of this study was to gain essential information on the diversity of aquatic invertebrates in Llancanelo basin by focussing the analysis on the zooplankton community and exploring seasonal and spatial differences in the zooplankton assemblages of this vulnerable wetland system within an arid region of Argentina. Seasonal samples were taken at nine sites in the basin (a shallow lake, 4 springs, streams, and the Malargüe River). A total of 45 species were identified. The zooplankton abundance in the lake displayed a clear seasonal contrast and was higher than that recorded in the springs and lotic environments. Boeckella poopoensis, Fabrea salina, and Brachionus plicatilis predominated in the lake, indicating their halophilia. The presence of the crustaceans Alona sp., Macrocyclops albidus, and Paracyclops fimbriatus was restricted to the springs; whereas Notholca labis and Notholca squamula were found only in running water. The zooplankton species richness in the Llancanelo area is low because of both the salt content in the lake and the irregularity of freshwater entry in all locations during the annual cycle.     

Effects of net height of crab entangling nets on the capture of targeted economically important portunid species and non-target species

The aim of this study was to determine the effects of net height on the capture performance of crab entangling nets. Fishing trials were conducted using nets at varying net heights (1) 12 meshes down (MD), (2) 24 MD and (3) 50 MD. A total of 1290 individuals comprising 87 species belonging to 53 families were caught. One-way analysis of variance showed that net height significantly affected the various catch parameters, including catch per unit effort (CPUE) of the total and target catch, amount of non-target catch, size of catch and species richness. The use of appropriate net height is a potential technical measure for a selective but still efficient crab entangling net fishery. Lower net height significantly reduced non-target catch by up to 70%. Lower net height also decreased the CPUE of target catch such as Portunus pelagicus and Charybdis feriatus by up to 65% at 12 MD, but catch at 24 MD was not significantly different than that at 50 MD. The use of a net height of 24 MD also resulted in the capture of larger-sized P. pelagicus. The richness of the catch species decreased by up to 58% in lower nets. These results are useful to fishery managers and government institutions when developing and/or improving existing regulations towards a sustainable crab fishery, particularly blue swimming crabs.     

Molecular evolution of myoglobin in the Tibetan Plateau endemic schizothoracine fish (<Emphasis Type="Italic">Cyprinidae</Emphasis>, <Emphasis Type="Italic">Teleostei</Emphasis>) and tissue-specific expression changes under hypoxia

Myoglobin (Mb) is an oxygen-binding hemoprotein that was once thought to be exclusively expressed in oxidative myocytes of skeletal and cardiac muscle where it serves in oxygen storage and facilitates intracellular oxygen diffusion. In this study, we cloned the coding sequence of the Mb gene from four species, representing three groups, of the schizothoracine fish endemic to the Qinghai-Tibetan Plateau (QTP), then conducted molecular evolution analyses. We also investigated tissue expression patterns of Mb and the expression response to moderate and severe hypoxia at the mRNA and protein levels in a representative of the highly specialized schizothoracine fish species, Schizopygopsis pylzovi. Molecular evolution analyses showed that Mb from the highly specialized schizothoracine fish have undergone positive selection and one positively selected residue (81L) was identified, which is located in the F helix, close to or in contact with the heme. We present tentative evidence that the Mb duplication event occurred in the ancestor of the schizothoracine and Cyprininae fish (common carp and goldfish), and that the Mb2 paralog was subsequently lost in the schizothoracine fish. In S. pylzovi, Mb mRNA is expressed in various tissues with the exception of the intestine and gill, but all such tissues, including the liver, muscle, kidney, brain, eye, and skin, expressed very low levels of Mb mRNA (<?8.0%) relative to that of the heart. The trace levels of Mb expression in non-muscle tissues are perhaps the major reason why non-muscle Mb remained undiscovered for so long. The expression response of the Mb gene to hypoxia at the mRNA and protein levels was strikingly different in S. pylzovi compared to that found in the common carp, medaka, zebrafish, and goldfish, suggesting that the hypoxia response of Mb in fish may be species and tissue-specific. Notably, severe hypoxia induced significant expression of Mb at the mRNA and protein levels in the S. pylzovi heart, which suggests Mb has a major role in the supply of oxygen to the heart of Tibetan Plateau fish.