Jellyfish as food

Jellyfish have been exploited commercially by Chinese as an important food for more than a thousand years. Semi-dried jellyfish represent a multi-million dollar seafood business in Asia. Traditional processing methods involve a multi-phase processing procedure using a mixture of salt (NaCl) and alum (AlK[SO₄]₂12 H₂O) to reduce the water content, decrease the pH, and firm the texture. Processed jellyfish have a special crunchy and crispy texture. They are then desalted in water before preparing for consumption. Interest in utilizing Stomolophus meleagris L. Agassiz, cannonball jellyfish, from the U. S. as food has increased recently because of high consumer demand in Asia. Desalted ready-to-use (RTU) cannonball jellyfish consists of approximately 95% water and 4–5% protein, which provides a very low caloric value. Cannonball jellyfish collagen has shown a suppressing effect on antigen-induced arthritis in laboratory rats. With the great abundance of cannonball jellyfish in the U. S. coastal waters, turning this jellyfish into value-added products could have tremendous environmental and economic benefits.     

Distribution and feeding habitat characterization of whale sharks Rhincodon typus in a protected area in the north Caribbean Sea

The relationship between the distribution of the whale shark Rhincodon typus and hydrobiological variables in the Caribbean Sea during 2005–2009 was analysed. Monthly trips were made to the R. typus aggregation area during the months when this species is present in the region (May to September) to record sightings and hydrological data and to collect samples to determine nutrients, chlorophyll a (Chl a) and zooplankton biomass. A total of 2104 R. typus were counted and three zones of high abundance were identified: Cabo‐Catoche, Contoy (both within the Whale Shark Biosphere Reserve, WSBR) and the zone knows as Afuera. The zones of greatest R. typus density within the WSBR were characterized by high Chl a concentrations (median: 1·1 mg m^?3, interpercentile range: 0·5–1·8 mg m^?3) and high nutrient concentrations, such as ammonium (median: 2·5 µmol l^?1, interpercentile range: 0·5–6·4 µmol l^?1), due to the influence of local upwelling. A generalized additive model (GAM) was used to explore the relationship between R. typus distribution and the environmental variables inside WSBR. Zooplankton biomass was the most influential environmental variable, supporting the close relationship between R. typus distribution and biological productivity. Copepods were the dominant zooplankton group within the WSBR. In the Afuera zone, there were large R. typus aggregations (>80 individuals) associated with zooplankton dominated by fish eggs and significantly higher mean ± s.d. biomass (3356·1 ± 1960·8 mg m^?3) compared with that recorded inside the WSBR (103·5 ± 57·2 mg m^?3). The differences among zones generated changes in R. typus distribution patterns and provided opportunities to develop local management strategies for this species.     

Inferred global connectivity of whale shark Rhincodon typus populations

Ten years have passed since the last synopsis of whale shark Rhincodon typus biogeography. While a recent review of the species' biology and ecology summarized the vast data collected since then, it is clear that information on population geographic connectivity, migration and demography of R. typus is still limited and scattered. Understanding R. typus migratory behaviour is central to its conservation management considering the genetic evidence suggesting local aggregations are connected at the generational scale over entire ocean basins. By collating available data on sightings, tracked movements and distribution information, this review provides evidence for the hypothesis of broad‐scale connectivity among populations, and generates a model describing how the world's R. typus are part of a single, global meta‐population. Rhincodon typus occurrence timings and distribution patterns make possible a connection between several aggregation sites in the Indian Ocean. The present conceptual model and validating data lend support to the hypothesis that R. typus are able to move among the three largest ocean basins with a minimum total travelling time of around 2–4 years. The model provides a worldwide perspective of possible R. typus migration routes, and suggests a modified focus for additional research to test its predictions. The framework can be used to trim the hypotheses for R. typus movements and aggregation timings, thereby isolating possible mating and breeding areas that are currently unknown. This will assist endeavours to predict the longer‐term response of the species to ocean warming and changing patterns of human‐induced mortality.     

Do they stay or do they go? Acoustic monitoring of whale sharks at Ningaloo Marine Park,Western Australia

Whale sharks Rhincodon typus were monitored via acoustic transmitters at the northern end of Western Australia's Ningaloo Marine Park to establish the extent to which the species inhabits the region beyond the whale‐shark ecotourism industry season, which usually extends from March to August in each year. Despite the vast majority (c. 98%) of photographic submissions of R. typus from Ningaloo Reef being between March and August, acoustic detections from the tagged R. typus at Ningaloo were recorded in all months of the year, but do not preclude the occurrence of extended absences. It is concluded that as a species, R. typus occurs year round at Ningaloo, where it generally remains in close proximity to the reef edge, but that some individuals move outside of the detection range of the array for extended periods.     

Comparison of the lateral line and ampullary systems of two species of shovelnose ray

The anatomical characteristics of the mechanoreceptive lateral line system and electrosensory ampullae of Lorenzini of Rhinobatos typus and Aptychotrema rostrata are compared. The spatial distribution of somatic pores of both sensory systems is quite similar, as lateral line canals are bordered by electrosensory pore fields. Lateral line canals form a sub-epidermal, bilaterally symmetrical net on the dorsal and ventral surfaces; canals contain a nearly continuous row of sensory neuromasts along their length and are either non-pored or pored. Pored canals are connected to the surface through a single terminal pore or additionally possess numerous tubules along their length. On the dorsal surface of R. typus, all canals of the lateral line occur in the same locations as those of A. rostrata. Tubules branching off the lateral line canals of R. typus are ramified, which contrasts with the straight tubules of A. rostrata. The ventral prenasal lateral line canals of R. typus are pored and possess branched tubules in contrast to the non-pored straight canals in A. rostrata. Pores of the ampullae of Lorenzini are restricted to the cephalic region of the disk, extending only slightly onto the pectoral fins in both species. Ampullary canals penetrate subdermally and are detached from the dermis. Ampullae occur clustered together, and can be surrounded by capsules of connective tissue. We divided the somatic pores of the ampullae of Lorenzini of R. typus into 12 pore fields (10 in A. rostrata), corresponding to innervation and cluster formation. The total number of ampullary pores found on the ventral skin surface of R. typus is approximately six times higher (four times higher in A. rostrata) than dorsally. Pores are concentrated around the mouth, in the abdominal area between the gills and along the rostral cartilage. The ampullae of both species of shovelnose ray are multi-alveolate macroampullae, sensu Andres and von Düring (1988). Both the pore patterns and the distribution of the ampullary clusters in R. typus differ from A. rostrata, although a basic pore distribution pattern is conserved.     

Hoarding patterns of sigmodontine rodent species in the Central Monte Desert (Argentina)

Hoarding food is an important strategy of rodents in desert environments characterized by unpredictable and poor food resource availability. In the Monte Desert, Prosopis produces abundant food, unevenly in time and space, in the form of pods and seeds. Sigmodontine rodents (Graomys griseoflavus, Akodon molinae, Eligmodontia typus and Calomys musculinus) use Prosopis propagules extensively, and they could be predators or dispersers depending on how they handle and where they leave the propagules. The objectives of this study were: (1) to know what rodent species transported propagules; (2) to evaluate what hoarding pattern was used by species that transport propagules (larder and scatterhoarding); and (3) to analyse in which condition were propagules left by the rodent species, both at the food source and in caches. Our results showed that all four species transported propagules, with G. griseoflavus and E. typus being the species that carried more seeds. Our study supported the evidence that food caching is common among species and that many species both larderhoard and scatterhoard food. Graomys griseoflavus and A. molinae, the largest species, larderhoarded more than did the smaller E. typus. These results uphold the hypothesis that larger species will show greater propensity to larderhoard than smaller species. Considering the interaction between seed‐hoarding patterns and plants, E. typus was the species that could most improve germination because it scatterhoarded propagules and left seeds out of pods. In contrast, G. griseoflavus could have a negative impact on plant populations because this was the species that predated more seeds and larderhoarded a high percentage of them. The smallest C. musculinus was the species that transported propagules least, and left them as seeds inside pods or pod segments mainly at the food source, which makes seeds more vulnerable to predation.     

基于环境DNA宏条形码技术的辽东湾典型围海养殖池塘内水母多样性研究

研究使用环境DNA宏条形码技术(eDNA metabarcoding)检测辽东湾东北部河口区围海养殖池塘水母种类多样性,探索适用于水母种类物种鉴定和监测的新方法。利用环境DNA宏条形码技术,分别基于18S rDNA和COI宏条形码检测了辽东湾东北部河口区围海养殖池塘水母种类多样性,通过水样采集、过滤、eDNA提取、遗传标记扩增、测序与生物信息分析的环境DNA宏条形码标准化分析流程,从围海养殖池塘7个采样点中获得可检测的采样点数据。结果显示,基于18S rDNA宏条形码检测出8种水母种类,其中钵水母纲大型水母2种、水螅水母总纲小型水母6种;基于COI宏条形码技术共检测出19种水母种类,其中钵水母纲大型水母5种、水螅水母总纲小型水母14种;两种DNA条形码标记都显示养殖种类海蜇(Rhopilema esculentum)为优势种。研究结果表明,环境DNA宏条形码技术作为一种新兴的生物多样性监测手段可用于快速检测水母种类多样性,在水母类物种鉴定、监测及早期预警中有较大的应用潜能。     

Cryptic diets of forage fish: jellyfish consumption observed in the Celtic Sea and western English Channel

To establish if fishes’ consumption of jellyfish changes through the year, we conducted a molecular gut-content assessment on opportunistically sampled species from the Celtic Sea in October and compared these with samples previously collected in February and March from the Irish Sea. Mackerel Scomber scombrus were found to feed on hydrozoan jellyfish relatively frequently in autumn, with rare consumption also detected in sardine Sardina pilchardus and sprat Sprattus sprattus. By October, moon jellyfish Aurelia aurita appeared to have escaped predation, potentially through somatic growth and the development of stinging tentacles. This is in contrast with sampling in February and March where A. aurita ephyrae were heavily preyed upon. No significant change in predation rate was observed in S. sprattus, but jellyfish predation by S. scombrus feeding in autumn was significantly higher than that seen during winter. This increase in consumption appears to be driven by the consumption of different, smaller jellyfish species than were targeted during the winter.     

A new species of Dermopristis Kearn, Whittington & Evans-Gowing, 2010 (Monogenea: Microbothriidae), with observations on associations between the gut diverticula and reproductive system and on the presence of denticles in the nasal fossae of the host Glaucostegus typus (Bennett) (Elasmobranchii: Rhinobatidae)

Dermopristis cairae n. sp. (Monogenea: Microbothriidae) is described from the skin and possibly from the nasal fossae of the giant shovel-nosed ray Glaucostegus typus (Bennett). The new species is distinguished from D. paradoxus Kearn, Whittington & Evans-Gowing, 2010 by its larger size, body shape, lack of transverse ridges on the ventral surface and absence of a seminal receptacle. Extensive short gut branches lie dorsal to the testes and adjacent to the coiled region of the vas deferens and the o?type, possibly reflecting high metabolic demand in these areas. Denticles are present in the lining of the nasal fossae of G. typus, providing a firm substrate for the cement-based attachment of a microbothriid. However, confirmation that D. cairae inhabits the nasal fossae of G. typus is required.     

Whale sharks Rhincodon typus get cleaned by the blue-streak cleaner wrasse Labroides dimidiatus and the moon wrasse Thalassoma lunare in the Philippines

Cleaning interactions are essential for healthy marine ecosystem communities. This study reports the first documentation of the whale shark Rhincodon typus cleaning behaviour in the Indo-West Pacific by two wrasse species, the blue-streak cleaner wrasse Labroides dimidiatus and the moon wrasse Thalassoma lunare in Cebu, Philippines. This study documented 36 cleaning interactions with 14 individual whale sharks. The cleaning interactions appear opportunistic rather than targeted by the sharks, unlike that observed in other species of elasmobranchs. Further work should focus on understanding the drivers of these unique cleaning interactions.     

Population structure and residency of whale sharks Rhincodon typus at Utila,Bay Islands,Honduras

There were 479 reported whale shark Rhincodon typus encounters between 1999 and 2011 at the island of Utila, which forms part of the Meso‐American Barrier Reef System (MBRS) in the western Caribbean Sea. The majority of R. typus were found to feed on small bait fish associated with various tuna species. Ninety‐five individual R. typus, ranging from 2 to 11 m total length (L_T), were identified through their unique spot patterns. A significant male bias (65%) was present. There was no significant difference between the mean ± s.d . L_T of female (6·66 ± 1·65 m) and male (6·25 ± 1·60 m) R. typus. Most R. typus were transient to Utila, with 78% sighted only within a single calendar year, although some individuals were sighted in up to 5 years. Mean residency time was modelled to be 11·76 days using maximum likelihood methods.     

Whale shark Rhincodon typus strandings in the Gulf of California,Mexico

The present study analyses whale shark Rhincodon typus stranding in the Gulf of California, Mexico, reported by the public, scientists, authorities and artisanal fishermen. A total of 14 strandings were documented during the period 2001–2018. The total length of R. typus ranged from 350–1,102 cm, with a sex ratio of 3.5:1 (males: females). This study highlights potential stranding areas, the need for better stranding protocols to assist R. typus recovery and the importance of samples from dead animals for scientific research.     

Taxonomic revision of the genus Cutleria proposing a new genus Mutimo to accommodate M. cylindricus (Cutleriaceae,Phaeophyceae)

Molecular phylogenetic analyses of representative Cutleria species using mitochondrial cox3, chloroplast psaA, psbA and rbcL gene sequences showed that C. cylindrica Okamura was not included in the clade composed of other Cutleria species including the generitype C. multifida (Turner) Greville and the related taxon Zanardinia typus (Nardo) P.C. Silva. Instead, C. cylindrica was sister to the clade composed of the two genera excluding C. cylindrica. Cutleria spp. have heteromophic life histories and their gametophytes are rather diverse in gross morphology, from compressed or cylindrical‐branched to fan‐shaped, whereas the sporophytes are rather similar. In contrast, the monotypic species Z. typus has an isomorphic life history and resembles fan‐shaped Cutleria in morphology. Morphological comparisons of these taxa revealed that C. cylindrica is morphologically distinct from other Cutleria spp. and Z. typus in having cylindrical gametophytes with multiseriate trichothallic filaments instead of uniseriate filaments (hairs) characteristic of Cutleriales (or Cutleriaceae, Tilopteridales), and in lacking rhizoidal filaments in the crustose sporophytes. Therefore, based on the molecular and morphological data, the establishment of a new genus Mutimo to accommodate C. cylindrica, and the new combination of M. cylindricus, is proposed.     

Northernmost record of a whale shark Rhincodon typus from the Sea of Okhotsk

The whale shark Rhincodon typus is the world's largest fish and it occurs in tropical, subtropical and warm temperate waters. Here, the northernmost record of R. typus is reported, when it was found in the Sea of Okhotsk for the first time. This occurrence can be explained by the unusually high sea surface temperature during the summer of 2012.     

Population structure of a whale shark Rhincodon typus aggregation in the Red Sea

The presence of whale sharks Rhincodon typus were recorded around Shib Habil, a small, coastal reef off the Red Sea coast of Saudi Arabia, from 2010 to 2015. A total of 267 suitable photographs resulting in the identification of 136 individuals, were documented from 305 encounters. Sharks were divided evenly between the sexes with no evidence of temporal or spatial segregation. All individuals were immature based on size estimates and, for males, juvenile clasper morphology. Scars were reported for 57% of R. typus with 15% showing evidence of propeller trauma. Estimates of population size and patterns of residency were calculated by modelling the lagged identification rate. Multiple models were run simultaneously and compared using the Akaike information criterion. An open population model was found to best represent the data and estimates a daily abundance between 15 and 34 R. typus during the aggregation season, with local residence times ranging from 4 to 44 days. Residence times away from Shib Habil range from 15 to 156 days with a permanent emigration–death rate between 0·07 and 0·58 individuals year^?1. These results are broadly similar to those from other aggregations of R. typus, although the observed sexual parity and integration found at this site is unique for the species and needs further study.     

Does seawater acidification affect zooxanthellae density and health in the invasive upside‐down jellyfish,Cassiopea spp.?

Ocean acidification is the decline in seawater pH that results from the absorption of atmospheric carbon dioxide (CO₂). Decreased pH has negative effects on survivability, growth, and development in many marine calcifiers, potentially resulting in reduced coral species richness. This reduction in richness could open new niche space, allowing the spread of invasive species, such as the upside‐down jellyfish (Cassiopea spp.). Like corals, this jellyfish forms symbiotic relationships with zooxanthellae, photosynthetic dinoflagellates. This study focused on the effect of seawater acidification in Cassiopea spp. We monitored zooxanthellae density and two measures of health (bell diameter and volume) in individuals of Cassiopea sp. at three pH levels chosen to mimic different open‐ocean average conditions: 8.2, representing pre‐industrial revolution conditions; and 7.9 and 7.6, representing predicted declines in pH in the next century. Zooxanthellae density and health of the jellyfish were measured twice—prior to experimental manipulations and after four weeks of exposure to experimental pHs—in three consecutive trials. The effects of pH and Trial on proportional change in jellyfish attributes were analyzed using generalized linear mixed models. We found no significant effects of either factor. These results indicate that decreasing seawater pH has no apparent negative effect on zooxanthellae density or health in Cassiopea, which suggests that these jellyfish may be relatively insensitive to the impacts of ocean acidification, heightening its potential as an invasive species.     

Length–weight relationships of three fish species from the South China Sea

The length–weight relationships were determined for three fish species: Histiopterus typus (Temminck & Schlegel, 1844), Branchiostegus argentatus (Cuvier, 1830), and Ilisha elongata (Anonymous [Bennett], 1830). Samples were collected from the South China Sea with commercial trawls in June 2016 using trawl nets. Prior to this study the length–weight relationships for these three species were unknown.     

Predation potential of the jellyfish Drymonema larsoni Bayha & Dawson (Scyphozoa: Drymonematidae) on the moon jellyfish Aurelia sp. in the northern Gulf of Mexico

The jellyfish Drymonema larsoni bloomed in the northern Gulf of Mexico in the Fall of 2000 and fed voraciously on the moon jellyfish Aurelia sp., especially where they were concentrated in frontal convergence. We evaluated the predation potential of D. larsoni on Aurelia sp. medusa using laboratory and field data. Our data set represents the most complete study to date on the new scyphozoan family Drymonematidae and indicates that D. larsoni may be one of the most effective predators on other jellyfish recorded to date. On average, each D. larsoni medusa contained 2.7 Aurelia sp. prey, but as many as 34. In addition, 94% of moon jellyfish unassociated with D. larsoni showed scarring from previous contact with D. larsoni tentacles. Digestion times for D. larsoni feeding on individual Aurelia sp. ranged from 2 to 3 h and averaged 2.7 h. Potential clearance rates for predation on Aurelia sp. were extremely high (320–1043.5 m³ d⁻¹) and indicate that D. larsoni is potentially an important predator on Aurelia sp. blooms where the species co-occur. When the two species co-occur in numbers, predation by D. larsoni medusae could reduce moon jellyfish blooms, possibly alleviating predation pressure on lower trophic levels utilized by Aurelia sp., such as copepods and the early life history stages of ecologically and economically important fish and invertebrate species.     

Locomotion and Escape Modes in Rodents of the Monte Desert (Argentina)

Modes of locomotion and escape tactics are attributes that affect the structure of animal communities, promoting exploitation of different microhabitats and the coexistence of different species. Bipedal locomotion is considered to be more effective than a quadrupedal gait in escaping attacks by predators because it allows for higher speed, a faster response to attack, sudden changes of direction and better detection of aerial raptors. The aim of this study was to determine the type of locomotion used at the moment of escape by three rodent species of the Monte desert –Eligmodontia typus, Akodon molinae and Graomys griseoflavus. The study was carried out in three plant communities of the Ñacuñán Reserve (Mendoza). All three species showed differences in both mode of escape and locomotory pattern. Graomys griseoflavus exhibited the highest proportion of escapes using quadrupedal saltation. The mode of locomotion employed by E. typus varied according to the type of plant communities it inhabited. Those occurring at open sites (Medanal community) exhibited a greater propensity to jump during escapes than those from more sheltered habitats (Algarrobal community). Akodon molinae relied primarily on a quadrupedal gait when fleeing from predators, which would explain its greater dependence on plant cover. Therefore, the morphological and behavioural characteristics of these species are related to their mode of locomotion and the strategies they employ to diminish the risk of predation.     

Assessment of habitat quality for four small mammal species of the Monte Desert, Argentina

In the temperate desert of Argentina, the combined action of climatic and anthropogenic factors has contributed to the formation of a highly heterogeneous landscape. In the central region of the Monte desert, four small mammal species (Eligmodontia typus, Calomys musculinus, Akodon molinae and Graomys griseoflavus) coexist and show different habitat uses in response to spatial variability. Three main habitat types are present in the region: mesquite forest, the creosotebush community and sand dunes. These habitat types are present also in the surrounding grazing area.The objective of this study was to determine habitat quality for these species in a protected area (Reserve MaB Ñacuñán) and in the adjacent grazed area. For each species we estimated demographic parameters that are highly correlated to fitness in each habitat, and for both treatments (protected and grazed).We found that the protected area offered a higher quality habitat than the grazed area for all species, but principally A. molinae and G. griseoflavus. At a local scale, we found that A. molinae and C. musculinus clearly showed higher fitness in the more complex habitats as the creosotebush community and the mesquite forest. In contrast, for E. typus, open and simplest patches, such as sand dunes, were optimal for its survival and reproduction.