White L. vannamei have become the most widely cultivated shrimp species worldwide. Cultivation of L. vannamei is one of the predominant sectors in China’s aquaculture industry. This study focused on the physiological and biochemical responses, differential protein expression, and expression characteristics of the related crucial functional protein genes under low oxygen conditions among different strains of L. vannamei. It was found that 6 h of hypoxic stress caused a significant reduction in the total hemocyte number in both strains, while the hypoxia-sensitive strain showed a stronger reduction. In contrast, the hemocyanin concentration showed only an overall upward trend. Proteomic analysis of L. vannamei muscle tissue revealed 3,417 differential proteins after 12 h of hypoxic stress. Among them, 29 differentially expressed proteins were downregulated and 244 were upregulated in the hypoxia-sensitive strain. In contrast, there were only 10 differentially expressed proteins with a downregulation pattern and 25 with an upregulation pattern in the hypoxia-tolerant strain. Five protein genes that responded significantly to hypoxic stress were selected for quantitative real-time PCR analysis, namely, hemocyanin, chitinase, heat shock protein 90 (HSP 90), programmed death protein, and glycogen phosphorylase. The results showed that the gene expression patterns were consistent with proteomic experimental data except for death protein and glycogen phosphorylase. These results can enrich the general knowledge of hypoxic stress in L. vannamei and the information provided differentially expressed proteins which may be used to assist breeding programs of L. vannamei of new strains with tolerance to hypoxia.

Anthropogenic noise pollution is increasingly acknowledged as a major threat to marine ecosystems, especially for sound-sensitive species, such as the large yellow croaker (Larimichthys crocea). While the effects of underwater noise on fish behavior and physiology have been well-documented, its influence on oxygen metabolism across varying temperatures remains poorly understood. This study examines the impact of boat noise on the oxygen consumption rate (OCR) of juvenile large yellow croakers at different temperatures, a key factor in their metabolic activity. The underwater noise generated by a fishing boat spans a broad frequency range, with a peak spectrum level of 130 dB re 1 µPa at low frequencies between 100 and 200 Hz. Our findings reveal that boat noise significantly elevates the OCR of juvenile fish, with mass-specific OCR increasing by 65.0%, 35.3%, and 28.9% at 18 °C, 25 °C, and 30 °C, respectively. Similarly, individual OCR rose by 60.7%, 35.3%, and 17.1% at these temperatures. These results demonstrate that boat noise triggers a stress response in fish, resulting in heightened metabolic demands across different seasonal conditions. Notably, the impact of boat noise on respiratory metabolism is most significant at lower temperatures. In aquatic environments with stable oxygen levels, the noise-induced rise in oxygen consumption could lead to hypoxia and provoke maladaptive behavioral changes in fish.

Length-Weight Relationship and Growth of a Marine Gastropod Mollusk, Hemifusus ternatanus (Gmelin) (Family: Melongenidae)

Gracilaria edulis, a marine red macroalgae, is a rich source of sulfated polysaccharides, carbohydrate, vitamins, and minerals, and showed multiple bioactivities such as antibacterial, antitumour, and cholinesterase inhibitory activity. The plastid genome sequence of G. edulis is 179,410 bp. A total of 235 genes were determined, including 201 protein-encoding genes, 30 tRNA genes, 3 rRNA genes, 1 ribonuclease gene, and 1 intron inserted into the trnM gene. Phylogenetic analysis showed that G. edulis clustered together with Gracilaria salicornia, Gracilaria tenuistipitata var. liui and Gracilaria chilensis. The plastid genome analysis will help in the understanding of Gracilaria evolution.

This study investigates the auditory capabilities of Golden Rabbitfish (Siganus guttatus) and the potential efficacy of sound-based deterrent methods for behavior control. Behavioral experiments were conducted on Golden Rabbitfish to assess their responses to sound stimuli. Sinusoidal pulses in the range of 100~800 Hz, based on previous research on auditory evoked potentials (AEPs), were utilized. An analysis of behavioral trajectories, swimming speed, and acceleration changes revealed the fish’s reactions to varying frequency sound stimuli. The results indicate that Golden Rabbitfish exhibited increased swimming activity and speed when stimulated by sound and notably moved away from the source under prolonged exposure to low-frequency acoustic signals. Specifically, the fish displayed the most significant response to 200 Hz sinusoidal pulses with a response threshold of 113~126 dB. These findings suggest that Golden Rabbitfish are particularly sensitive to low-frequency noise, aligning with AEP study outcomes. This study concludes that employing sound stimuli to deter Golden Rabbitfish in practical settings holds promise for mitigating economic losses in seaweed farming due to Golden Rabbitfish grazing.

Gracilaria spinulosa is an economical species of marine red algae. The length of its plastid genome sequence is 179,082 bp; a total of 236 genes were determined, including 203 protein-encoding genes, 3 rRNA genes, 29 tRNA genes, 1 ribonuclease gene, and 1 intron inserted into the trnM gene. The gene content and structure of Gracilariaceae species were relatively well conserved. Phylogenetic analysis showed that G. spinulosa had a closer relationship with Gracilaria salicornia in Gracilaria. The complete plastid genome sequence provided will help the understanding of Gracilaria evolution.