A comparison of GAM and GWR in modelling spatial distribution of Japanese mantis shrimp (Oratosquilla oratoria) in coastal waters

The Japanese mantis shrimp Oratosquilla oratoria usually lives in the mud bottom. This species excavates a U-shaped tunnel with a sarge and a small opening on a tidal flat; the length of burrow is proportional to occupant size. Artificial burrows of various diameters and lengths were made of polyvinyl chloride pipes and used to study this selective habit in large aquaria. The results showed that the species had a significant preference on the basis of diameter of pipe, but not for pipe length above a lower limit. These facts and behaviour in the artificial burrow suggest that a normal life-cycle is dependent upon habitation of a burrow of compatible size. An artificial burrow of favourable size permits feeding, spawning, etc. and increases survival of mantis shrimp reared in the laboratory.

The spawning and egg mass nursing behaviour, together with the change in external appearance of the egg mass, of the mud-dwelling Japanese mantis shrimp Oratosquilla oratoria were studied using artificial burrows in aquaria. This species usually spawns in a supine posture in the burrow maintaining this posture with the back of abdomen and exopods of uropods against the wall of burrow for almost 3 h. The newly extruded egg mass is amorphous, but the female shrimp compacts it and then shapes it into a thick disc within 1 h and to a thin disc having a marginal turnup within 24 h of spawning. All maxillipeds excluding the raptorial claw are used for the nursing behaviour, i.e. spreading and folding the egg mass, so it is teased out and becomes a tuft shape after 3 days or so. The second gee laying occurred in 2 females about 40 days after the first spawning of each individual at 25°C, and this fact suggests that O. oratoria may spawn more than once in a spawning season in natural warm waters.

The maximum and minimum prey sizes of the Japanese mantis shrimp Oratosquilla oratoria were estimated from equations based on the morphology of the raptorial claw (second maxilliped) and from foraging behaviour. The optimal prey size was predicted, theoretically, from these values and experiments confirming this prediction were conducted using living prey shrimps and artificial prey models. The preferred prey size was approximately the mean between the maximum and minimum values obtained theoretically.

This study investigated the characteristics of the digestive system in adult Japanese mantis shrimp (Oratosquilla oratoria), which is a species of carnivorous crustacean, with a focus on morphological and histological analysis. The digestive system of O. oratoria includes the mouthparts, the esophagus, cardiac stomach, pyloric stomach, midgut, hindgut, anus and hepatopancreas. The histological structure of each organ is composed of the mucosal epithelial layer, submucous layer, muscularis, and outer membrane. Besides, the foregut is covered with a diverse chitinous layer. The labrum is densely populated with minor salivary glands. The mandibular-gastric mill apparatus and evenly arranged bifurcated setae are observed in the cardiac stomach. The secondary filter of the pyloric stomach is subtly intricate, with fine spicules and seta plate. The midgut, being the longest segment of the digestive tract and accounting for 59.39% of body length, has villi covered with dense microvilli. The hindgut also forms villi, but the height of the villi (695.96 μm) is 3.20 times that of the midgut (217.41 μm). The hepatopancreas encircles the entire pyloric stomach, midgut, and hindgut. The hepatosomatic index is approximately 3.83%.

Transcriptome analyses reveal alterations in muscle metabolism, immune responses and reproductive behavior of Japanese mantis shrimp (Oratosquilla oratoria) at different cold temperature

Simple SummaryRising ocean temperature would change the seawater chemistry and affect the external and internal physiology of crustaceans due to their lack of certain efficient temperature regulators. In addition, the infraspecific populations of crustaceans might also have different response strategies to the rising of temperature. Therefore, we identified the transcriptomic variations to the same thermal stress between ecologically divergent populations of Oratosquilla oratoria. The aim of this study was to investigate the population-specific function genes and relevant pathways in response to thermal stress in O. oratoria. The results showed that gene-expressed variation was in a population-specific pattern, which indicated that the local environment could lead to the evolvement of changes in gene regulation, ultimately leading to adaptive divergences. Additionally, we found several genes with large pleiotropic effects in the Zhoushan population, which might indicate that the regulation mechanisms of the Zhoushan population were more efficient than those of the Qingdao population under same thermal stress. The results provided some novel insights into the local adaptive differences of the infraspecific populations of O. oratoria and other crustaceans.Crustaceans are generally considered more sensitive to ocean warming due to their lack of certain efficient regulators. However, the alterations in the physiology and behavior of crustaceans in response to thermal stress differ vastly even among the infraspecific populations of heterogeneous landscapes. Consequently, understanding the impact of temperature fluctuation on crustacean infraspecific populations might be essential for maintaining a sustainable persistence of populations at existing locations. In the present study, we chose the Japanese mantis shrimp (Oratosquilla oratoria) as the representative crustacean population, and conducted transcriptome analyses in two divergent O. oratoria populations (the Zhoushan and Qingdao populations) under same thermal stress (20–28 °C) to identify the population-specific expression response to thermal stress. The results showed significant differences in gene expressions, GO terms and metabolic pathways between the two populations. We hypothesized that intraspecific mutations in the same or different genes might lead to thermal adaptive divergences. Temperature increases from 20–28 °C produced significant enrichment in GO terms and altered the metabolic pathways in the Zhoushan population despite the lack of differentially expressed unigenes. Therefore, several functional genes with large pleiotropic effects may underlie the response to thermal stress in the Zhoushan population. Furthermore, the most significantly enriched biological processes of the Qingdao population were associated with the state or activity of cells and its significant enriched pathways with genetic information processing as well as immune and environmental information processing. In contrast, the differentially regulated unigenes of the Zhoushan population were primarily involved in the regulatory cellular and transcription processes and the most significant pathways found were metabolic and digestive. Consequently, the regulatory mechanisms of the Zhoushan population are probably more efficient than those of the Qingdao population under the same thermal stress.

Identification of putative key genes for thermal adaptation in the Japanese mantis shrimp (Oratosquilla oratoria) through population genomic analysis

The heterogeneous seascapes in the northwestern Pacific (NWP) can be important selective forces driving adaptive divergence of marine coastal species distributed along the gradients. Here, we tested this hypothesis in Japanese mantis shrimp (Oratosquilla oratoria) with a wide distribution in the NWP and a significant north-south population structure. To this end, the full-length (FL) transcriptomes of northern and southern O. oratoria were firstly sequenced using PacBio single molecule real-time sequencing technology. Based on the FL transcriptome data, we captured large-scale FL transcripts of O. oratoria and predicted the FL transcriptome structure, including coding region, transcription factor and long noncoding RNA. To reveal the divergence between northern and southern O. oratoria, we identified 2,182 pairs of orthologous genes and inferred their sequence divergences. The average differences in coding, 5’ untranslated and 3’ untranslated region were 1.44%, 2.79% and 1.46%, respectively, providing additional support to previous proposition that northern and southern O. oratoria are two species. We provided further evolutionary context to our analysis by identifying positive selected genes (PSGs) between northern and southern O. oratoria. In total, 98 orthologs were found evolving under positive selection and involved several environmentally responsive genes associated with stress response, immunity and cytoskeletal organization, etc. Furthermore, we found PSGs also diverged in gene expression response of northern and southern O. oratoria to heat stress. These findings not only highlight the importance of genetic variation in these genes in adapting to environmental changes in O. oratoria, but also suggest that natural selection may act on the plasticity of gene expression to facilitate O. oratoria adaptation to environmental gradients. Overall, our work contributes to understanding how marine coastal species has evolved to adapt to heterogeneous seascapes in the NWP.

The Japanese mantis shrimp, Oratosquilla oratoria (De Haan), is one of the main target species for small-scale trawlers in Tokyo Bay. In order to take appropriate fisheries management measures, it is required to evaluate precisely the present condition of 0. oratoria stock. In this study, we examined the change in composition of the market size categories of this species using monthly landing data from 1977 to 1989 and evaluated the present fishing intensity to the stock based on the fisheries and biological parameters determined by the authors previously.Analyses showed that the percentage of large market size categories especially in summer to total landings has declined, but this is due to the increase of total landings containing small individuals because of the increased upper limit of landings by one fishing vessel per day. A decrease of absolute landings of large market size categories was not confirmed. Judging from the stock assessment using both the yield isopleth diagram and results of biological analysis (calculation of the rate of decrease of spawning adults), the present fishing intensity for O. oratoria stock in Tokyo Bay was at around the optimum level.

Trophic dynamics is one of the major regulators of fishery production in marine ecosystems, which is important for the implementation of ecosystem-based fisheries management. Based on data collected form bottom trawl surveys in Haizhou Bay and adjacent waters during autumn of 2011 and 2018, Delta-GAMMs (Delta-generalized additive mixed models) were constructed to evaluate the effects of biotic and abiotic factors on the predation of five key prey species (including Leptochela gracilis, Alpheus japonicus, Loligo spp., Larimichthys polyactis, and Oratosquilla oratoria) in the Haizhou Bay. Percent frequency of occurrence and predation pressure index were used to identify their major predators. Variance inflation factor and full subsets regression were analyzed to quantify the degree of multicollinearity between these factors. The results showed that the occurrence frequency of keystone prey species in the stomach of predators ranged from 8.5% to 42.2%, and the weight percentage ranged from 4.2% to 40.9%. The average deviance explanation rate of the "binomial" model was 16.1%, and the average deviance explanation rate of the "positive" model was 23.8%. Body length of predator, predator population density, and sea bottom temperature were important factors influencing prey-predator trophic interactions. Predator length was the most important factor, with feeding probability and weight percentage of keystone prey species all increasing with body length of predator. Feeding probability and weight percentage of key prey species decreased with predator population density. The effects of environmental factors such as sea bottom temperature, depth of water, latitude, and sea bottom salinity showed different trends, depending on the prey-predator assemblage. This study showed that the Delta-GAMMs was an effective method to explore the trophic interactions between prey and predators in marine ecosystems, and could provide a theoretical basis for the conservation and sustainable use of fisheries resources.

<strong class="journal-contentHeaderColor">Abstract.</strong> American lobsters (<i>Homarus americanus</i>) are an iconic species and are the socioeconomic and cultural mainstay for many communities across Nova Scotia. Describing the changes in population biomass and providing annual stock assessment advice for this species are required for sustainable fisheries. In many areas the best information available for providing this advice comes from commercial fishery data. Often there is an assumed relationship between fishery performance (catch per unit effort; CPUE) and available biomass; however several studies indicate that this relationship can be affected by external factors such as sea bottom temperature. Including bottom temperature when developing a standardized CPUE index will potentially address these concerns; however it has proven difficult in the past due to the lack of readily available (near-real-time) and unbiased bottom temperature data at the spatial and temporal scales required. Here we explore a global ocean reanalysis product of the European Union Copernicus Marine Service with an application to the fishery catch data from Lobster Fishing Area 33 during 2008–2023. A comparison with observational data shows that this reanalysis product provides realistic variations in sea bottom temperatures in this region. Next, a hierarchical generalized linear modelling approach is applied to evaluate the relationship between within-season changes in lobster CPUE and sea bottom temperature. Positive relationships between the rates of change of two model parameters, during the first 60 d of the fishing season (from mid-November to mid-January), are found in the majority of the 10 subregions. A standardized CPUE index with the influence of bottom temperature included, compared to the index without such influence, explains a high percentage of the deviance of CPUE data and hence is more consistent with available stock biomass. The outcomes of the model evaluation and relationship analysis encourage further applications of multi-decadal ocean reanalysis products to understand past changes, as well as the development of ocean forecasts for predicting future changes in marine ecosystems and fisheries, a product with wide-reaching socioeconomic value.

Crab species are economically and ecologically important in coastal ecosystems, and their spatial distributions are pivotal for conservation and fisheries management. This study was focused on modelling the spatial distributions of three Portunidae crabs (Charybdis bimaculata, Charybdis japonica, and Portunus trituberculatus) in Haizhou Bay, China. We applied three analytical approaches (Generalized additive model (GAM), random forest (RF), and artificial neural network (ANN)) to spring and fall bottom trawl survey data (2011, 2013–2016) to develop and compare species distribution models (SDMs). Model predictability was evaluated using cross-validation based on the observed species distribution. Results showed that sea bottom temperature (SBT), sea bottom salinity (SBS), and sediment type were the most important factors affecting crab distributions. The relative importance of candidate variables was not consistent among species, season, or model. In general, we found ANNs to have less stability than both RFs and GAMs. GAMs overall yielded the least complex response curve structure. C. japonica was more pronounced in southwestern portion of Haizhou Bay, and C. bimaculata tended to stay in offshore areas. P. trituberculatus was the least region-specific and exhibited substantial annual variations in abundance. The comparison of multiple SDMs was informative to understand species responses to environmental factors and predict species distributions. This study contributes to better understanding the environmental niches of crabs and demonstrates best practices for the application of SDMs for management and conservation planning.

This paper describes spatial relationships between whiting, Merlangius merlangus (Linnaeus, 1758), abundance in the northern North Sea and contemporaneous measures of environmental conditions: sea surface temperature (SST), sea bottom temperature (SBT), and depth, with particular reference to the processes underlying patterns in SST. Generalised additive models (GAMs) were used to provide quantitative descriptions of the relationships between local abundance and environmental conditions. GIS (geographic information system) techniques were used to provide qualitative description of spatial patterns and to confirm the results revealed from GAMs. GAMs fitted to both long-term averaged and individual years’ data revealed marked seasonal changes in the spatial relationships between whiting abundance and environmental variables. The GAM results were supported by GIS analysis. In winter and spring (December–April) in the northern North Sea, the spatial pattern of SST apparently has an important influence on the spatial distribution of whiting at the same time. Where the water is relatively warm whiting abundance is relatively high, probably reflecting the indirect influence of North Atlantic waters entering the northern North Sea. However, there are no consistent optimum SST bands for whiting. These positive relationships between abundance and SST disappear in summer.

Environmental effects on cephalopod community structure and distribution on the eastern Bering Sea upper continental slope.

Precise temperatures to depths of several hundred meters have been measured in abandoned petroleum exploration wells in coastal and offshore areas of the Canadian Arctic. In these regions, changes in relative sea level during the Quaternary have left a strong thermal signature on deep ground temperatures. Surface temperature changes of the order of 10–20 K accompanied shoreline emergence due to uplift in some regions and marine transgression due to eustatic changes in sea levels in others. Classical, analytic techniques are used to demonstrate that these anomalous features are a direct consequence of recent changes in sea level. In coastal areas of the Queen Elizabeth Islands, modelling of the large, near‐surface temperature‐depth gradients and the distinct curvature in the measured profiles yield emergence times in general agreement with dates taken from emergence curves. The analysis suggests that surface temperatures of these coastal areas were 16–19 K higher than at present from the Late Wisconsinan until emergence in the Holocene, suggesting either marine conditions for this period or glacial ice cover with basal temperatures near the pressure melting point. In contrast, at two offshore wells on the Beaufort Shelf, analyses of the negative temperature‐depth gradients below the seabed and profile curvature yield times of marine transgression generally consistent with the published sea level curve for the area. The analyses suggest that surface temperatures of some present offshore areas were 10–16 K lower than today's sea bottom temperatures from the Late Wisconsinan until marine transgression in the Holocene. The characteristic ground temperature profiles measured in such arctic areas provide independent evidence for the relative changes in sea level indicated by proxy data. It is especially valuable for these areas, where there is little historical record and from which datable material, such as shells, driftwood, and pumice fragments, may be scarce or ambiguous. These effects may not be observable in temperate areas because of the smaller contrast in sea bottom and terrestrial temperatures.