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Barred mudskipper (Periophthalmus argentilineatus) has a potency to be developed as protein for human consumption and ornamental fish. The fish also has an important role in mangrove ecosystems. Nevertheless, many barred mudskippers have been considered a cryptic species. Therefore, accurate identification is needed to clarify species identification of the barred mudskipper using DNA barcoding. This research aimed to identify barred mudskippers from Tekolok Estuary (East Lombok, West Nusa Tenggara, Indonesia) using COI mitochondrial gene as a DNA barcode and analyze genetic relationship with other barred mudskippers from several regions of Indonesia recorded in GenBank. This study used a PCR method with universal primers FishF2 and FishR2. The data was then analysed using DNASTAR, BLAST, Mesquite, MEGA, DnaSP, BEAST, GenAlEx, and NETWORK. The results revealed that barred mudskipper from Tekolok Estuary has been verified as Periophthalmus argentilineatus. The results also exhibited that P. argentilineatus from Tekolok Estuary has a close genetic relationship to P.argentilineatus from Tukad Bilukpoh (Jembrana, Bali). In addition, phylogenetic analysis showed that P.argentilineatus from Indonesia consisted of two clades with a genetic distance of approximately 6.64%. This analysis revealed evidence of the cryptic diversity of P.argentilineatus from Indonesia. Further detailed studies are needed to clarify whether Indonesian P.argentilineatus should be categorized into more than one species or single species with several subspecies.

Temperature has a profound effect on all life and a particularly influential effect on ectotherms, such as fishes. Amphibious fishes have a variety of strategies, both physiological and/or behavioural, to cope with a broad range of thermal conditions. This study examined the relationship between prolonged (5 weeks) exposure to a range of temperatures (22, 25, 28, or 32 degrees C) on oxygen uptake rate and movement behaviours (i.e., thermoregulation and emergence) in a common amphibious fish, the barred mudskipper (Periophthalmus argentilneatuis). At the highest temperature examined (32 degrees C, approximately 5 degrees C above their summer average temperatures), barred mudskippers exhibited 33.7-97.7% greater oxygen uptake rates at rest ((M) over dotO(2Rest)), emerged at a higher temperature (CTe; i.e., a modified critical thermal maxima (CTMax) methodology) of 41.3 +/- 0.3 degrees C relative to those maintained at 28, 25, or 22 degrees C. The 32 degrees C-maintained fish also ceased movement activity at the highest holding temperature suggesting that prolonged submergence at elevated temperatures is physiologically and energetically stressful to the individual. Using exhaustive exercise protocols with and without air exposure to simulate a predatory chase, the time to recovery was examined for all individuals. When submerged, mudskippers required 2.5x longer recovery time to return to resting oxygen uptake from exhaustive exercise than those fully emerged in air. Oxygen uptake data revealed that air exposure did not accrue oxygen debt, thereby allowing faster return to resting oxygen consumption rates. If the option to emerge was not available, mudskippers preferentially sought more benign water temperatures (26.7 +/- 2.1 degrees C), resembling those experienced by these fish during the Austral autumn, regardless of prolonged exposure higher or lower temperatures. These results add to our understanding of the strategies that amphibious fishes may use to mitigate extra costs associated with living in warm waters, and could be the key to understanding how such species will cope with increasing temperatures in the future.

Thermal tolerance niche analyses have been used extensively to identify adaptive thermal tactics used by wholly aquatic fishes, however no study to date has quantified thermal niche characteristics of air-breathing fishes. We use standardized thermal methodologies to estimate temperature acclimation ranges, upper and lower acclimation response ratios, and thermal niche areas in common (Periophthalmus kalolo) and barred (Periophthalmus argentilineatus) mudskippers in air and water. Common and barred mudskippers had an upper chronic limit of 37.0 °C, and respective low chronic temperatures of 14.0 and 11.4 °C, resulting in acclimation scope values of 23.0 °C and 25.6 °C. Both fishes had moderately large thermal niches, with barred mudskipper expressing larger niche areas in both water and air than common mudskipper (676.6 and 704.2 °C2 compared to 641.6 and 646.5 °C2). Acclimation response ratios were relatively low, with fish gaining or losing between 0.10 and 0.43 °C of heat tolerance with each 1 °C change in acclimation temperature. Although intraspecific total niche areas remained largely unchanged between media (≤10%), both species showed a slight increase in heat tolerance but a notable upward shift in intrinsic tolerance when emerged. Media-dependent thermal niche adjustment is a unique, and thus far undescribed physiological adaptation that in combination with behavioral responses, allow mudskippers to thrive in some of the most austere thermal environments experienced by any fish.

Contains fulltext : 34631.pdf (Publisher’s version ) (Closed access) The potential feeding advantages that are offered to the barred mudskipper Periophthalmus argentilineatus by its amphibious life-style were investigated. To this end the feeding ecology of these fish, the position they occupy in the mangrove food web and the importance of different morphological factors for their diet were studied. Analysis of gut contents showed that the major component of the barred mudskipper diet changes during growth from small crustaceans (e.g. copepods and amphipods) to polychaetes to mangrove crabs. This dietary shift was found to be facilitated through enlargement of the mouth, as well as elongation of the gut. The use of stable isotope analysis revealed that barred mudskippers had a similar trophic position as other zoobenthivore fish species, but that their diet did not appear to be affected by competition for food with other zoobenthivores. The amphibious habits of the barred mudskipper provide specific advantages to its feeding ecology, such as access to an abundant food source of mangrove crabs, which are mostly inaccessible for other fish species.

The complete mitochondrial genome sequence of the barred mudskipper Periophthalmus argentilineatus was first determined in this study. The circle genome was 16 509 bp long and consisted of 13 protein-coding genes, 2 rRNA genes, 22 tRNA genes, and 1 control region. The nucleotide composition of the heavy strand of P. argentilineatus is 28.28% for A, 27.83% for C, 16.01% for T, and 27.88% for G, with a slight G + C bias of 55.71%. Only the NADH dehydrogenase subunit 6 (ND6) and eight tRNA genes were encoded on the light strand, other mitochondrial genes were all encoded on the heavy strand. The mitochondrial gene arrangement of P. argentilineatus is similar to those of most other gobies. The phylogenetic analysis using the neighbor-joining method showed that the kinship between Periophthalmus and Boleophthalmus is closer than those between Periophthalmus and other selected genera. Periophthalmus argentilineatus was clustered into one branch with other four species from the same genus Periophthalmus.

SUMMARY Escape responses in fishes are rapid behaviors that are critical for survival. The barred mudskipper (Periophthalmus argentilineatus) is an amphibious fish that must avoid predators in two environments. We compared mudskipper terrestrial and aquatic escapes to address two questions. First,how does an amphibious fish perform an escape response in a terrestrial environment? Second, how similar is a terrestrial escape response to an aquatic escape response? Because a mudskipper on land does not have to contend with the high viscosity of water, we predicted that, if the same behavior is employed across environments, terrestrial escape responses should have`better' performance (higher velocity and more rapid completion of movements)when compared with aquatic escape responses. By contrast, we predicted that intervertebral bending would be similar across environments because previous studies of escape response behaviors in fishes have proposed that vertebral morphology constrains intervertebral bending. High-speed digital imaging was used to record mudskipper escapes in water and on land, and the resulting images were used to calculate intervertebral bending during the preparatory phase, peak velocity and acceleration of the center of mass during the propulsive phase, and relative timing of movements. Although similar maximum velocities are achieved across environments, terrestrial responses are distinct from aquatic responses. During terrestrial escapes, mudskippers produce greater axial bending in the preparatory phase, but only in the posterior region of the body and over a much longer time period. Mudskippers also occasionally produced the `wrong' behavior for a given environment. Thus,it appears that the same locomotor morphology is recruited differently by the central nervous system to produce a distinct behavior appropriate for each environment.