Red Crab Research Articles

PSV-29 In vitro digestibility and in situ degradability of lobster and mixed crab shell waste material

Abstract The objective of this research was to determine the in situ and in vitro degradability of lobster shell waste meal (LM) and crab shell waste meal (CM). Lobster and crab harvest are major industries within the New England states and the Maritime provinces. Harvest of the American lobster amounts to 54,643 tons caught and processed in 2020 in the New England states. The Atlantic Red Crab annual quota is around 1,814 tons. The Jonah Crab amounts to 5,725 tons. Due to the significant harvest, there is a resulting increase in byproducts and wastes at processing facilities providing potential feedstuffs for cattle. For both experiments, LM and CM were compared with soybean (SBM) and blood meals (BM). In experiment 1, 0.5 g of each meal were added to an artificial rumen incubator (Daisy, Ankom technologies) and DM degradability over 48 h was measured. In experiment 2, ruminally-cannulated Holstein cows (n = 4) in a 4 × 4 Latin square, had 5 g of sample were placed in Dacron bags in the dorsal rumen. Bags were in duplicate and removed at 2, 4, 8,12, 24, and 48 h time points. Eight bags were removed at 12 h for use in the in vitro intestinal degradability measurement using the modified three-step technique. Contrasts were: SBM vs. BM+LM+CM (SBM vs others), BM vs. LM+CM, and LM vs. CM. In experiment 2, 0 h bags served as a determination of fraction A, while the 48 h bags served as fraction C. Fraction B = 100% - (fraction A + fraction C). Degradation rate (kd) was calculated by converting % CP degraded from 2 to 24 h to Ln and then calculating the slope. In experiment 1, DM degradation was 45.8, 43.8, 76.4 and 100.1 % for SBM, BM, LM, and CM respectively; SBM vs others (P < 0.01), BM vs. LM + CM (P < 0.01), and no difference between LM vs. CM. Fraction A (CP) was 9.9, 8.1, 4.2, and 4.8% respectively; with SBM vs. others (P < 0.03), BM vs. LM+CM (P < 0.01), and no difference between LM vs CM. Fraction B (CP) was 76.2, 62.2, 28.9, and 42.6% respectively; with SBM vs. others (P < 0.01), BM vs. LM + CM (P < 0.01), and LM vs. CM (P < 0.10). Fraction C (CP) was 4.41, 30.8, 46.8, and 37.5% respectively; with SBM vs. others (P < 0.01), BM vs. LM + CM (P < 0.03), and LM vs. CM (P < 0.08). Intestinal CP digestibility was 56.2, 64.7, -5.83, and 10.5% respectively, with SBM vs others (P < 0.01), BM vs LM+CM (P < 0.01), and no difference between LM and CM. Results of these studies indicated that LM and CM may have some benefits in cattle diets, but feeding studies should be conducted.

A multi-centennial drought reconstruction from tree-rings reveals a growing threat to Christmas Island’s water resources

Small islands that depend on limited freshwater resources are at significant risk from seasonal drought, which poses a major threat to both their ecosystems and communities. Christmas Island, located in the eastern Indian Ocean, presents an example for which severe drought conditions during the wet season not only affects its freshwater resources but also biodiversity on the island, including the migration pattern of the iconic red crab species. However, short-term instrumental climate records on this island make it hard to quantify drought variability and assess its associated risks. Tree growth is affected by drought via reduced soil moisture, and hydroclimate reconstruction from tree-ring chronologies can therefore provide longer-term information on historical variability of dry and wet periods. Here, we reconstructed the wet season (December-May) self-calibrating Palmer Drought Severity Index (scPDSI) for Christmas Island using 64 remote tree-ring chronologies from Asia, Australia, and New Zealand. scPDSI was reconstructed using the Point-to-Point Regression (PPR) method and compared with regional marine coral proxies for independent verification. The remote tree-ring chronologies explained more than 66 percent of scPDSI variance (R-squared) over the calibration period. The trees identified as significant predictors in the regression model were primarily located in areas affected by the Indo-Pacific climate drivers including the Indian Ocean Dipole (IOD). The reconstructions span 1540 CE to 2000. During the first four centuries of this period, the frequency of extreme (5th percentile) droughts and pluvial events rarely exceeded one event per 13 years. In contrast, the frequency of both extremes experienced an unprecedented increase during the 20th century, and with a notable shift towards dry conditions. These findings highlight a significant shift towards more frequent and severe dry conditions during the wet season on Christmas Island, posing a challenge to water resource management and potentially threatening the island's ecosystem and services to the community.

The comparison of morphology and transcriptome in the inner membrane reveals the potential mechanism of the heritable carapace color of the Chinese mitten crab Eriocheir sinensis

Carapace color plays an important role in the communication, reproduction, and self-defense of crustaceans, which is also related to their economic value. Chinese mitten crab (Eriocheir sinensis) is an important aquaculture species in China, and there are different strains with heritable carapace colors, i.e. Green, White, and Red. However, there is a lack of research on the formation mechanism of carapace color of this species. This study was conducted to compare the histology and transcriptome in the inner membrane of three carapace color strains of E. sinensis. Histological comparisons revealed that the inner membrane of green and red carapace crabs contained more melanin, appearing in clusters, and had a higher presence of yellow or orange pigments. In contrast, the inner membrane of white carapace crabs had smaller and fewer melanin particles, as well as a lower presence of yellow or orange pigments. Observation under an electron microscope showed that the inner membrane of E. sinensis contained a large number of collagen fibers and various types of cells, including fibroblasts, melanocytes, and other tissue cells, which exhibited different levels of activity. Transcriptome analysis showed that the Green, Red, and White strains of E. sinensis had approximately 80.3 K, 81.6 K and 80.3 K expressed unigenes in their inner membranes, respectively. When comparing Green and Red crabs, there were 2, 850 upregulated genes and 2, 240 downregulated genes. In the comparison between Red and White crabs, there were 2, 853 upregulated genes and 2, 583 downregulated genes. Furthermore, there were 2, 336 upregulated genes and 2, 738 downregulated genes in the inner membranes between White and Green crabs. Among these genes, some members of the solute carriers family, which are involved in carotenoid transportation, showed differential expression among the three carapace color strains. Additionally, significant differences were observed in the expression of genes related to melanin synthesis, including wingless/integrate, tyrosinase, guanine nucleotide-binding protein inhibitory subunit, cell adhesion molecule, adenylyl cyclase, and creb-binding protein. there were no differences in the gene expression levels of the crustacyanin family. In conclusion, this study identified several candidate genes associated with carapace color in the inner membrane of E. sinensis, suggesting a close relationship between the heritable carapace colors and the transport of the carotenoids as well as the synthesis of melanin.

An effective method for the simultaneous extraction of 173 contaminants of emerging concern in freshwater invasive species and its application

A robust and efficient extraction method was developed to detect a broad range of pollutants of emerging interest in three freshwater invasive species: American red crab (Prokambarus clarkii), Asian clam (Corbicula fluminea), and pumpkinseed fish (Lepomis gibbosus). One native species, “petxinot” clam (Anodonta cygnea), was also evaluated. Invasive species are often more resistant to contamination and could be used in biomonitoring studies to assess the effect of contaminants of emerging concern on aquatic ecosystems while preserving potentially threatened native species. So far, most extraction methods developed for this purpose have focused on analyzing fish and generally focus on a limited number of compounds, especially analyzing compounds from the same family. In this sense, we set out to optimize a method that would allow the simultaneous extraction of 87 PhACs, 11 flame retardants, 21 per- and poly-fluoroalkyl substances, and 54 pesticides. The optimized method is based on ultrasound-assisted solvent extraction. Two tests were performed during method development, one to choose the extraction solvent with the best recovery efficiencies and one to select the best clean-up. The analysis was performed by high-performance liquid chromatography coupled to high-resolution mass spectrometry. The method obtained recoveries between 40 and 120% and relative standard deviations of less than 25% for 85% of the analytes in the four validated matrices. Limits of quantification between 0.01 ng g−1 and 22 ng g−1 were obtained. Application of the method on real samples from the Albufera Natural Park of Valencia (Spain) confirmed the presence of contaminants of emerging concern in all samples, such as acetaminophen, hydrochlorothiazide, tramadol, PFOS, carbendazim, and fenthion. PFAS were the group of compounds with the highest mean concentrations. C. fluminea was the species with the highest detection frequency, and P. clarkii had the highest average concentrations, so its use is prioritized for biomonitoring studies.Graphical abstract

Island of Migrants

Christmas Island is a tiny island in the Indian Ocean, a few hundred miles off the coast of Java. The island is small, with a population of less than 2000. Yet in spite of, or maybe because of, its isolation, the island is a site of incredible movement. Every wet season, millions of endemic red crabs descend from the jungles in what is one of the most spectacular animal migrations in the world. In October or November, the crabs begin a long journey from the jungles down to the coast to breed, continuing an annual life cycle. The crab migration intersects the island’s main roads and has resulted in a series of inventive tunnels, bridges, and fences which both protect the crabs from traffic and draw tourists from around the world.[1]
 Another important population crosses Christmas Island on its migration journey, with considerably less luck. In 2007, construction was completed on an Immigration Reception and Processing Centre to temporarily detain asylum seekers from neighboring islands. In response to the 2001 Pacific Solution in which “4000 islands were excised from Australia’s migration zone,” Christmas Island became a temporary holding center for boat-bound asylum seekers from Indonesia, eventually transitioning to becoming an isolated site for long-term detention.[2] The center on Christmas Island is one of the largest in Australia’s onshore detention center network, which continues to operate today.
 For both animal and human populations, Christmas Island is the site of incredible movement. However, these two migrating populations are governed in very different ways. “Island of Migrants”[3] is a 19-minute podcast episode that examines the ways in which red crab migration and asylum seeker migration are treated differently despite their close physical proximity on the island, and what this difference in their treatment reflects about who is considered worthy of protection. The podcast is a result of both anthropological and journalistic methods as well as a 2-month period of living on Christmas Island. Through firsthand accounts from islander residents, asylum seekers, and activists, “Island of Migrants” seeks to demonstrate the stakes of valuing one migration over another.
 
 [1] “Red Crab Migration.” Australian Government. Parks Australia. Accessed December 16, 2019. https://parksaustralia.gov.au/christmas/discover/highlights/red-crab-migration/.
 [2] Hearman, Vannessa. “Troubled Transit: Asylum Seekers Stuck in Indonesia. By Antje Missbach.” Journal of Refugee Studies 30, no. 4 (January 2017): 628–30. https://doi.org/10.1093/jrs/fex031.
 [3] Niu, Stephanie. “Following the Water.” Following the Water (blog). Anchor, December 13, 2019. https://anchor.fm/followingthewater/episodes/Island-of-Migrants-e9gsaq/a-a15vv0b.

Spatial and Temporal Variability of Trace and Macro Elements in the Red Crab Pleuroncodes planipes in the Pacific Coast of the Baja California Peninsula, Mexico.

The red crab, Pleuroncodes planipes, is a decapod crustacean abundant off the Pacific coast of the Baja California Peninsula. This species is caught and used in preparing animal feed, such as flour, particularly for aquaculture. Levels of calcium (Ca), cadmium (Cd), copper (Cu), iron (Fe), lead (Pb), magnesium (Mg), manganese (Mn), nickel (Ni), phosphorus (P), and zinc (Zn) were measured in red crabs collected from three geographic zones during three cruises in different seasons. Significant differences were found in the levels of Ca, Cd, Cu, Fe, Mg, Ni, P, and Zn between the two El Niño years (cruises C1 and C3, based on a threshold of ±0.5 °C for the Oceanic Niño Index). The highest concentrations of most elements were observed in the south of the Baja California Peninsula, a highly productive area influenced by upwelling events. Our findings suggest that while environmental temperature plays a central role in the benthic or pelagic distribution of red crabs, their content and variability of trace and macro elements appear to be associated with the presence of oceanic conditions, such as upwelling and potential changes in the composition of their diet associated with the depth in which these crustaceans are collected.

Multi-sensor observation of a rapidly dispersing micronekton thin layer

Ocean midwaters—areas between the sunlit surface layers and seafloor—comprise the largest habitat on Earth but are among the least understood marine environments. Available sampling platforms (e.g. net systems, moored and shipboard sensors), are often unable to resolve the environmentally-coupled distributions of marine biota throughout the water column over the relevant scales. A deep profiling (1000 m rated) stereo camera was operated in tandem with a split-beam five channel fisheries echosounder to record midwater scattering layers in detail across the oxygen minimum zone (OMZ) offshore of Baja California. A computer vision software library was developed to batch process the collected water column imagery and the derived biological information was interpolated with environmental sensor and acoustic backscatter measurements. A large aggregation of the micronekton squat lobster Pleuroncondes planipes (red crab) was described in the imaging and acoustic data. During midday hours, the micronekton were distributed in a thin layer 1.4 m in vertical extent with a sharp lower boundary and having a maximum abundance of at least 10 individuals per m3. The thin layer distribution was tightly coupled to the 1026 kg/m3 isopycnal associated with a high-frequency internal wave. At dusk the crabs redistributed upwards suddenly as a specific mesopelagic scattering layer with a daytime settling depth of 600–800 m migrated through the P. planipes thin layer near the surface. The thin layer was not disrupted by the ascent of an earlier migrating layer suggesting a layer-selective migration response.

Feeding guilds among batoids in the northwest coast of the Baja California Sur, Mexico

AbstractResearch on the feeding habits of batoids provides information of intra and interspecific interactions of this taxon in marine ecosystems. We analyzed 832 stomachs of nine ray species collected from the artisanal fishery on the Northwest coast of Baja California Sur (NBCS). We identified 79 prey items assembled in five trophic groups (crustaceans, fish, mollusks, polychaetes, and sipunculidae). Results indicated that the red crabPleuroncodes planipeswas the most important prey in the diet of the seven batoid species. A low dietary similarity of the rays was observed, which evidenced different feeding strategies. In this regard, we identified four well‐separated trophic guilds. Each guild was characterized by the consumption of specific prey: (1)Hypanus dipterurusandNarcine entemedorthat fed mostly on polychaetes; (2)Rostroraja veleziandGymnura marmoratafed mostly on fishes (Clupeidae and Batrachoididae); (3)Hypanus longus,Myliobatis californica, andPlatyrhinoidis triseriatafed on crustaceans (Munnidae) and Sipunculus worms; and (4)Pseudobatos productusandZapteryx exasperatafed on crustaceans (Portunidae) and fishes (Synodontidae and Batrachoididae). We concluded that batoids off the NBCS show prey sharing between the different species.

The nutritional quality of the red mangrove crab (Ucides occidentalis), harvested at two reserves in the Guayas estuary

Crabs are an outstanding source of many essential nutrients. Little research has been performed on the nutritional quality of the red mangrove crab (Ucides occidentalis). In this research we investigated the proximate composition, fatty acid profile, amino acid composition, and mineral concentrations of red mangrove crabs sampled at two reserves within the Guayas estuary in Ecuador. Furthermore, we evaluated the influence of spatial variation. We found that the red mangrove is a good source of nutrition for a balanced diet and can contribute to the recommended intake of essential nutrients. Also, the red mangrove crab obtained better lipid nutritional quality indices compared to other shellfish species, apart from the EPA + DHA index values. Current research indicated that the final nutritional quality indices of the red crab were not influenced by harvest site. More research into the influence of environmental and ecological factors on the nutritional composition of crabs is suggested.

Pacific bluefin tuna, Thunnus orientalis, exhibits a flexible feeding ecology in the Southern California Bight.

Pacific bluefin tuna, Thunnus orientalis, migrates from spawning grounds in the western Pacific Ocean to foraging grounds in the California Current System (CCS), where they are thought to specialize on high energy, surface schooling prey. However, there has been substantial variability in estimates of forage availability in the CCS over the past two decades. To examine the foraging ecology of juvenile T. orientalis in the face this variability, we quantified the diet and prey energetics of 963 individuals collected in the Southern California Bight (SCB) from 2008 to 2016. Using classification and regression tree analysis, we observed three sampling periods characterized by distinct prey. In 2008, T. orientalis diet was dominated by midwater lanternfishes and enoploteuthid squids. During 2009–2014, T. orientalis consumed diverse fishes, cephalopods, and crustaceans. Only in 2015–2016 did T. orientalis specialize on relatively high energy, surface schooling prey (e.g. anchovy, pelagic red crab). Despite containing the smallest prey, stomachs collected in 2009–2014 had the highest number of prey and similar total energetic contents to stomachs collected in 2015–2016. We demonstrate that T. orientalis is an opportunistic predator that can exhibit distinct foraging behaviors to exploit diverse forage. Expanding our understanding of T. orientalis foraging ecology will improve our ability to predict its responses to changes in resource availability as well as potential impacts on the fisheries it supports.

Embryonic analysis and larval culture of Ucides occidentalis

The purpose of this work is to disseminate the findings related to the reproduction trials of the species Ucides occidentalis, which are especially linked to the basic infrastructure and equipment for obtaining seeds. It is necessary to add that bibliographical information on this species is scarce, which is why it was associated with other types of organisms. It is explained from the capture of the females to the obtaining of the larval stage, remaining to complete the investigation, through future trials and new reproduction attempts. The monitoring of the females was for 90 days, and at this same time the development of larvae and water quality, microbiological and pathological analyzes were carried out. The main results show that the reproduction of Ucides occidentalis requires a study related to the management of the mothers and the larval development where several factors of great importance influence.
 Keywords: Red crab, embryo culture, larva.

Changes in the feeding habits of the bat ray Myliobatis californica (Gill 1865) during climatic anomalies off the west coast of the Baja California Peninsula, Mexico

The Mexican Pacific was influenced by “La Mancha” and “El Niño”, from 2014 and until 2016. The increase in sea surface temperature influenced the feeding habits of the bat ray (Myliobatis californica) in the northwest of Baja California Sur, Mexico. To evaluate possible changes in the diet, stomach content analysis and analysis of stable isotopes of carbon (δ13C) and nitrogen (δ15N) in muscle was performed during normal (2012 and 2013) and anomalous years (2014, 2015, and 2016). During the normal years, the main prey was the crab Dynomene spp. (% Prey Specific Relative Importance Index (PSIRI) = 29.3) and the stomatopod Hemisquilla californiensis (% PSIRI = 10.6). In contrast, during the anomalous years, these preys were replaced by the pelagic red crab Pleuroncodes planipes (% PSIRI = 28.5) and peanut worms Sipunculus spp. (% PSIRI = 7.9). During normal years the median isotopic values recorded were: δ13C = −16.2‰ and δ15N = 15.2‰. During the anomalous years, δ13C was −16.3‰ and δ15N was 15.1‰. Between the different periods no trophic (p (probability) > 0.05) or isotopic overlaps (p > 0.3) were found. The change in the diet of M. californica during the anomalous years is an adaptive response to the increase in water temperature caused by “La Mancha” and “El Niño”. The massive presence of P. planipes on the northwest coast of Baja California Sur is associated with the increase in water temperature, which makes P. planipes a food source for M. californica.

Morphometric characteristics of red crab (Thalamita spinimana) in Dompak Tanjungpinang Waters, Riau Islands

The morphometric characteristics of the red crab (Thalamita spinimana) have not been widely studied. This research was conducted from March to May 2021 in the waters of Dompak Tanjungpinang, Riau Islands. Each sample obtained directly measured the morphometric part using a caliper or calipers with an accuracy of 0.05 mm and the crab body weight was also weighed using a digital scale with an accuracy of 0.1 g. The samples obtained during the study were 119 crabs, of which 84 female red crabs and 35 male red crabs. The carapace width range for female crabs is 55.40 – 88.32 mm, while in male crabs the carapace width range is 16.35 and 34 individuals 68.96 – 90.94 mm. The weight of female red crabs is in the range of 50.0 – 103.6 g, while the weight of male crabs is in the range of 49.0 – 142.8 g.

Red mangrove crab Ucides occidentalis (Ortmann, 1987) (Brachyura: Ocypodidae): complete embryonic development under laboratory conditions

The red crab Ucides occidentalis (locally called "guariche") is widely distributed along Ecuador's coastline and is the most important crustacean fishery exploited by local coastal communities. However, a lack of information on the species' reproductive cycle has hindered conservation and sustainable management initiatives. Here we documented for the first time the complete embryonic development of U. occidentalis, based on its morphological traits. Thirteen ovigerous females were collected in the field, maintained in captivity, and fed with leaves and tender mangrove propagules. Egg samples were taken every 12 h and analyzed under the microscope to evaluate embryonic development. U. occidentalis eggs had eight different embryonic stages, which maintained their spherical shape during the entire developmental. The eggs were relatively small and uniform in size. The tenuous heart beating of the precursor coincided with the formation of chromatophores in stage V and became more frequent at stage VIII, just before hatching. The incubation period lasted 15 days. Despite the rapid development, the increase in egg size and volume was not uniform during sequential stages.

Feeding habits of Paralabrax nebulifer (Serranidae) during reproductive and non-reproductive seasons in an adjacent area to Magdalena Bay, Baja California Sur, Mexico

The barred sand bass Paralabrax nebulifer is a commercially important fish off the west coast of Baja California Sur. To assess the diet of this species and variations as a function of sex and reproductive condition, 60 specimens were captured using traps during seven seasonal sampling trips from August 2016 to August 2018 in an adjacent area to Magdalena Bay, Baja California Sur, Mexico. The stomach contents of 50 specimens were obtained (23 males and 27 females). Sex was diagnosed by direct observation of the gonads. Based on the gonadosomatic index, hepatosomatic index, and histological analyses, the reproductive season of the barred sand bass was corroborated for August 2016, April, August, and September 2017, and August 2018, and the non-reproductive season was corroborated for November 2016 and March 2018. The Index of Relative Importance (IRI) was used to classify the main diet components, which comprised three fish species, seven crustacean species, and one mollusk species. According to the IRI, the South American pilchard Sardinops sagax and the red pelagic crab Pleuroncodes planipes were the prey that contributed the most (55%) to the barred sand bass diet. The ANOSIM showed that there were significant differences in the amount and type of prey consumed by sex; the SIMPER analysis revealed that the species contributing the most to differences between the sexes were S. sagax (16.58%), Euphylax dovii (15.95%), Stenocionops ovata (12%), and P. planipes (11.82%) for females. There were significant differences in the amount and type of prey consumed between types of reproductive season; the species contributing the most to differences between seasons were Anchoa spp. (27.76%), and P. planipes for non-reproductive season (22.67%), and S. sagax (11.08%) for reproductive season. The feeding strategy of the barred sand bass was that of a specialist carnivorous predator that fed mainly on the fish Sardinops sagax during the reproductive season, which supply the dietary nutritional requirements of the lipids HUFA (arachidonic acid, 20:4n-6; eicosapentaenoic acid, 20:5n-3; docosahexaenoic acid, 22:6n-3), nutrients required to achieve reproductive success.

Defining deep-sea fishery stocks through multiple methods: The case of the red crab Chaceon notialis Manning & Holthuis, 1989 (Crustacea, Decapoda, Geryonidae) in the Southwestern Atlantic

The red crab Chaceon notialis is endemic to the Southwestern Atlantic (Brazil, Uruguay and Argentina), occurring from 200 to 1600 m deep. The species belongs to the Geryonidae family and exhibits a K-strategist life cycle. Due to its increased exploitation over recent decades, this marine resource requires attention regarding its conservation and management. In this work, were analyzed red crab populations from the three countries that cover the species' entire distribution range, assessing diversity and differentiation through morphometric and genetic analyses. The evaluated morphometric measurements were length and width of the carapace; length, width and height of the chelae propodus; and female abdomen width. For genetic evaluation, the following mitochondrial DNA regions were used: the partial 12S gene and the entire Control Region (861 bp); and the partial Cytochrome c oxidase subunit I (1252 bp). The morphometric results showed two distinct phenotypic groups (one from Brazil/Uruguay and the other from Argentina), with significant differences in female abdomen width and chela size. Genetic analyses, however, revealed only a single panmictic population, with no genetic structuring among the analyzed stocks. These findings suggest that the management measures applied in each country will influence the population dynamics of the others, and that international cooperation is necessary for achieving sustainable fisheries of this valuable resource. Since commercial fishing of the red crab C. notialis is not conducted in Argentina, we propose that this area can act as a biological reserve for this species. Due to the commercial importance of this crab, knowledge of the species’ diversity is of fundamental importance for its management, conservation, and to provide baselines for future biological and ecological studies.

Maturity level of female red swimming crab gonads (<i>Thalamita spinimana</i>) in Dompak Waters, Tanjungpinang, Riau Island

Red crab (Thalamita spinimana) is a type of crab that has a light body color, favored by coastal communities for its thick meat and high protein content at a low selling price. This research purpose to determine the maturity level of female red crabs. This research was conducted using a survey method with sampling twice for two months which was carried out from April to May 2021 in Dompak Waters, Tanjungpinang. The results of the research found that TKG I was immature gonads. Female red crabs incubate eggs (Ovigerous) with yellow and orange color, dominated by immature gonads, while brown and dark gray colors are dominated by mature gonads.

Development of prediction models for adsorption properties of chitin and chitosan for micropollutants

Chitin and its derivative, chitosan, are common bioresources and possess well-developed functional groups; therefore, they have been used as adsorbents to remove micropollutants during wastewater treatment. To efficiently use them in the removal process, it is necessary to understand and predict the adsorption properties of chitin and chitosan for micropollutants because there are numerous types of micropollutants. Therefore, we measured the adsorption affinities of raw types of chitin and chitosan for approximately 30 types of micropollutants in neutral or ionic forms. Then, the measured properties were predicted using experimentally determined and theoretically calculated linear free energy relationship (LFER) descriptors. The experimental results revealed that the adsorption affinities depended on the chemical structures of the micropollutants, and of chitin and chitosan possess similar adsorption properties. Next, the relationships between the adsorption affinities of the adsorbents and quantitative structural properties of the adsorbates were analyzed using experimental and in silico calculated LFER descriptors. The results indicated that the experimental descriptors could predict the properties of chitin and chitosan within R2 of 0.832 and 0.827, respectively; moreover, the calculated descriptors could predict the properties of chitin and chitosan within R2 of 0.812 and 0.867, respectively. In addition, since chitin obtained from the red crab contains some impurities, the effect of impurities on adsorption after washing it with methanol and water was investigated. The results showed that the effect of impurities on adsorption was negligible. Using the developed models, based on the measured descriptors, it was identified that the main driving forces of chitin and chitosan were H-bonding donor moment and ionic electrostatic attraction.

Anomalous poleward advection facilitates episodic range expansions of pelagic red crabs in the eastern North Pacific

AbstractThe episodic stranding of millions of pelagic red crabs (Pleuroncodes planipes) along California beaches is a striking and puzzling phenomenon. Pleuroncodes planipes are usually abundant off Baja California, Mexico, and their appearance in central California is thought to coincide with anomalously warm waters and northward advection related to El Niño. This anecdotal association has stimulated many hypotheses, but no hypothesis has gained clear and convincing support. Motivated by an unprecedented number of P. planipes strandings and at‐sea observations in 2015–2019, we compiled 10 P. planipes datasets spanning 1950–2019, tested the anomalous advection hypothesis using a transport analysis from 1981 to 2010, and explored other compelling hypotheses. We found P. planipes presence off central California was related to anomalous advection of waters from Mexico, sometimes but not always associated with El Niño events, with P. planipes likely remaining residents of northern waters for several years without additional anomalous transport but potentially facilitated by warm waters. By identifying a mechanism behind episodic P. planipes range expansions, we show that a source water index could provide an early indicator for anomalous events in the future.

New record and range extension of the primnoid octocoral Verticillata castellviae in the Southwest Atlantic Ocean

In this study we report the presence of the soft coral Verticillata castellviae at 947 m deep, off Buenos Aires Province, Argentina, which constitutes the northernmost record for this species. The specimen was collected as a bycatch species with a troncopyramidal trap during an experimental cruise devoted to the study of the red crab Chaceon notialis and the Patagonian lobsterette Thymops birsteini.