The Sediment Reworking of the Mud Shrimp Laomedia sp. (Crustacea: Laomediidae) with Tidal Conditions in the Intertidal Sediments of Gomso Bay, Korea

Although the thalassinidean mud shrimp Laomedia sp. is one of the most abundant species in the upper tidal flats along the west coast of Korea, little is known of its ecological characteristics and bioturbation effects on intertidal sediments. This study estimated the sediment reworking rate (SRR) of Laomedia sp. by quantifying in situ sediments ejected from the burrows via direct entrapment and evaluated the effects of tidal conditions on the SRR. The amount of expelled sediments from individual burrows was significantly related to the duration of submergence, whereas SRR showed an increasing trend as elevation increased. The SRR of Laomedia sp. was estimated to be 40 g ind.−1 d−1 and the annual SRR of this species was 72.2 kg m−2 yr−1 based on the density in the study area, which is very high compared to other thalassinidean shrimp. These findings suggest that Laomedia sp. is an important bioturbator in intertidal sediments, and tidal conditions should be considered when evaluating the SRR of this species.

Development and Characterization of 177 SNP Markers in The Mud Shrimp Upogebia Major

The mud shrimp Upogebia major (De Haan, 1841) (Crustacea, Decapoda, Gebiidea) is an important species widely distributed in coastal shallow waters. As an active initiation species, it has contributed significantly to the maintenance of coastal benthic biodiversity. However, there is still a lack of effective molecular markers to effectively protect and manage this species. In this study, we used the DNeasy Blood & Tissue kit to extract DNA and Illumina HiSeq 4000 sequencing technology to obtain SNP marker resources. 177 single nucleotide polymorphism (SNP) markers were developed and characterized in U. major. The minor allele frequency raged from 0.0500 to 0.5000. The observed heterozygosity and expected heterozygosity ranged from 0.0333 to 0.9000 and from 0.0966 to 0.5085, respectively. Polymorphic information content ranged from 0.0905 to 0.3750. The inbreeding coefficient values varied from − 0.2902 to 0.5968. Seventeen loci showed significant deviations from the Hardy-Weinberg equilibrium (P < 0.05). The polymorphic SNPs will be helpful for the further population genetic analysis and natural resource conservation of U. major.

Distribution and Sediment Selection by the Mud Shrimp Upogebia noronhensis (Crustacea: Thalassinidea) and the Potential Effects on the Associated Macroinfaunal Community

Burrowers such as thalassinideans remobilize sediment in benthic ecosystems, altering granulometry, enhancing organic matter cycling and oxygenation. We characterized the distribution of the mud shrimp Upogebia noronhensis and the associated macroinfauna along a depth and granulometric gradient in a shallow subtidal area in the southern Brazilian coast. Mud shrimp densities were estimated by burrow opening count using 0.25 m2 quadrats in three sediment zones: sand, sand-mud transition and mud. Macroinfaunal community descriptors and sediment granulometric characteristics were assessed. U. noronhensis average density varied from 0.6 to 145 individuals m−2 and was highest in the transition zone and lowest in the sand zone. Macrofauna in the sand zone was at least three times more abundant and 1.2 times richer, averaging 436.3 organisms and 39 species, while the transition and mud zones were more even in species distribution (species evenness > 0.7). The shrimp presence seems to be linked to a coarse sand content <80% and clay and silt <40% in the sediment, a compromise between gallery construction ability and filter-feeding suitability. High densities and aggregated distribution of mud shrimp, combined with alteration of sediment grain composition and organic matter, are likely to affect macroinfaunal abundance nearby the burrows.

Redescription of a poorly known upogebiid mud shrimp Gebiacantha acanthochela (Sakai, 1967) and description of a new species of the genus from the Ryukyu Islands, Japan (Decapoda: Gebiidea)

Two species of the upogebiida mud shrimp genus Gebiacantha Ngoc-Ho, 1989, currently represented by 19 described species, are reported from the Ryukyu Islands, Japan. The first, G. acanthochela (Sakai, 1967), is redescribed in detail based on two female specimens from Amami Islands the second discovered since the original description, enabling better assessment of its diagnostic characters. The second, G. fortispinata n. sp., is described on the basis of a single female holotype from Okinawa Island. It appears closest to G. multispinosa Ngoc-Ho, 1994, known with certainty only from New Caledonia, but the proportionally narrower telson with a more deeply notched posterior margin and the distally unarmed pereopod 3 merus distinguish the new species from G. multispinosa. Three species of Gebiacantha, including G. sagamiensis Komai, 2017, are now known from Japanese waters.

A new species of the mud shrimp genus Axianassa Schmitt, 1924 (Decapoda: Gebiidea: Laomediidae) from Japan

The laomediid mud shrimp genus Axianassa Schmitt, 1924 is currently represented by 12 species worldwide. In this study, a new species of the genus, A. microlepis, is described and illustrated on the basis of two female specimens obtained from Awaji Island, eastern part of the Seto Inland Sea, Japan, at depth of 8 m. The type specimens were collected by means of an airlift suction sampler, which enables collection of infauna in subtidal soft sediments. The new species, representing the fourth species of the genus known from the western Pacific, is readily distinguished from other congeners by the unique structure of the antennal scaphocerite (short, non-dagger shaped, terminally rounded or having spine and blade), faintly crenulate rostral margins and the presence of a small lateral notch on the uropodal endopod. An amended identification key to the species of Axianassa and Heteroaxianassa Sakai, 2016 is provided.

Catch performance and remaining ratio on fishing hooks for different baits used in longline fishery

In this study, the catch performance and remaining ratio on fishing hooks of natural alive mud shrimp (Upogebia pusilla) (CCK), siliconized mud shrimp (SCK) and siliconized pellet (SP) were investigated in a longline. The trials were carried out monthly between May 2016 and April 2017 in Zeytinlikuyu district of Kıyıkislacik Village – Milas-Mugla province. The main body diameter has 0.70 mm, leader and snoods have 0.40 mm. The snood length and distance is 1.5 m and 4.0 m, respectively. 14 no straight hooks were used. Totally 150 hooks, 50 for each bait were used and each bait was replaced in 25 hooks. The individuals caught during the samplings were separated as CCK, SCK and SP, and each individual was measured as the precision of mm the total length (TL) and weighted of 0.01 g. Totally 191 individuals from seven families with 18 different species were caught. Gilthead sea bream (Sparus aurata) was the abundant species with 48.7% in all bait type, and the followed by common pandora (Pagellus erythrinus) with 10.5%, common two-banded sea bream (Diplodus vulgaris) with 9.4% and annular sea bream (Diplodus annularis) with 8.9%. Of the 191 individuals, 55% (105 individuals) were caught with CCK, 33.5% (64 individuals) with SCK and 11.5% (22 individuals) with SP. The results of the trial with 3 different bait types were shoved that that there are significant differences between the catch rates of gilthead sea bream, annular and common two-banded sea bream (χ2, P<0.05). In paired tests between bait groups (CCK-SCK, CCK-SP and SCK-SP), there were no clear differences between the sizes of the individuals (ANOVA, P>0.05). Catch per unit effort (CPUE) values of CCK, SCK and SP were calculated as 0.05 n/h, 0.03 n/h and 0.01 n/h, respectively. In the same order, yield per unit effort (YPUE) values were determined as 7.28 g/h, 4.35 g/h and 2.99 g/h. When the remaining rate of baits on the hooks were evaluated, CCK gave the lowest rate with 6.32%2.01. It is thought that SCK should be used as an alternative particularly when natural mud shrimp cannot be utilized as alive or unable to be supplied due to the cold weather conditions and time restrictions. On the other hand, it is thought that performing such studies with bait made with natural binders such as gelatine instead of silicone will be extremely important in terms of less harm to both fish and nature.