Light is one of the most important environmental factors affecting the growth and reproduction of algae. In this study, the effect of various LED colors on the productivity, chlorophyll (Chl-a, Chl-b, and total Chl), protein, and carbohydrate content of Isochrysis zhanjiangensis in indoor culture was investigated. Microalgae monocultures were cultivated under five different colors (red, green, blue, yellow, and white) for twenty-one days. The microalgae cultured under red light exhibited a higher specific growth rate (0.4431 ± 0.0055 µ day⁻¹), and under white light a higher productivity (0.0728 ± 0.0013 g L⁻¹ day⁻¹). The poorest performance was observed under yellow and green lights. Interestingly, green light exhibited the highest levels of chlorophylls (Chl-a, 1.473 ± 0.037 mg L⁻¹; Chl-b, 1.504 ± 0.001 mg L⁻¹; total Chl, 2.827 ± 0.083 mg L⁻¹). The highest protein content was observed under the white light (524.1935 ± 6.5846 mg L⁻¹), whereas the carbohydrate content was remarkably high under the blue light (24.4697 ± 0.0206 mg L⁻¹). This study is important in terms of the selection of light at the appropriate color (wavelength) to increase the content of organic compounds desired to be obtained indoors with the potential for commercially produced cultures.

The escalating impact of human activities has led to the accumulation of microplastics (MPs) and heavy metals in marine environments, posing serious threats to marine ecosystems. As essential components of oceanic ecosystems, large seaweeds such as Caulerpa lentillifera play a crucial role in maintaining ecological balance. This study investigated the effects of MPs and cadmium (Cd) on the growth, physiology, biochemistry, and Cd accumulation in C. lentillifera while elucidating the underlying molecular regulatory mechanisms. The results demonstrated that exposure to MPs alone significantly promoted the growth. In contrast, exposure to Cd either alone or in combination with MPs significantly suppressed growth by reducing stem and stolon length, bud count, weight gain, and specific growth rates. Combined exposure to MPs and Cd exhibited the most pronounced inhibitory effect on growth. MPs had negligible impact while Cd exposure either alone or combined with MPs impaired antioxidant defenses and exacerbated oxidative damage; with combined exposure being the most detrimental. Analysis of Cd content revealed that MPs significantly increased Cd accumulation in algae intensifying its toxic effects. Gene expression analysis revealed that Cd exposure down-regulated key genes involved in photosynthesis, impairing both photosynthetic efficiency and energy conversion. The combined exposure of MPs and Cd further exacerbated these effects. In contrast, MPs alone activated the ribosome pathway, supporting ribosomal stability and protein synthesis. Additionally, both Cd exposure alone or in combination with MPs significantly reduced chlorophyll B and soluble sugar content, negatively impacting photosynthesis and nutrient accumulation. In summary, low concentrations of MPs promoted C. lentillifera growth, but the presence of Cd hindered it by disrupting photosynthesis and antioxidant mechanisms. Furthermore, the coexistence of MPs intensified the toxic effects of Cd. These findings enhance our understanding of how both MPs and Cd impact large seaweed ecosystems and provide crucial insights for assessing their ecological risks.

Industrial farming is an alternative mode for Pinctada maxima juvenile cultivation to avoid mass mortality caused by natural disasters. Suitable and enough food is crucial for successful industrial bivalve farming. To investigate the feasibility of live microalga instead of spray-dried microalgal powder in P. maxima juvenile industrial farming, this study replaces a positive control live microalgal diet [Isochrysis zhanjiangensis (L-iso) and Platymonas subcordiformis (L-pla)] with spray-dried I. zhanjiangensis powder (P-iso) and P. subcordiformis powder (P-pla). Continuous feeding trials (30 days) were conducted on the P. maxima juvenile (1.2008 ± 0.0009 g initial weight and 30.12 ± 0.05 mm initial shell length), under laboratory conditions. Survival, growth performance, and intestinal microbial community were studied and compared across the groups. Results showed that survival rate (SR) did not differ significantly across the groups (ranged from 84 to 86%, P > 0.05). The growth performance in spray-dried microalgal groups, including total weight (TW), shell height (SH), absolute growth rate (AGR), and relative growth rate (RGR) for SH and TW, was slightly lower than that in live microalgal groups, while the activities of pepsin (PES), amylase (AMS), and lipase (LPS) were significantly higher (P < 0.05). The best growth performance was observed in the L-iso group, followed by the L-pla group. A 16S rRNA-based sequencing revealed that Proteobacteria was the dominant phylum in P. maxima juvenile intestinal bacterial community under controlled conditions, which accounted for 62–82% across groups. The intestinal bacteria at the genus level were more sensitive to diets, whereas Burkholderia was the dominant genus in both L-iso (66.52 ± 6.43%) and L-pla groups (54.00 ± 5.66%), while Mycoplasma, Alphaproteobacteria, and Oxyphotobacteria were in both P-iso and P-pla groups. The P-pla group got higher ACE, Chao1, and Simpson and Shannon indices (P < 0.05). The above results suggested that the spray-dried P-iso and P-pla can serve as substitutes for live microalga in P. maxima juvenile industrial farming under controlled conditions. The finding in this study provides basic data to optimize industrial farming technology and healthy management for P. maxima juvenile.

Bivalves use byssal threads for attachment and locomotion, periodically shedding and regenerating them. In the winged pearl oyster Pteria penguin—known for its strong byssus and its role in the pearl industry—shedding may occur when the byssal stalk reaches a critical size, although the underlying mechanism remains unclear. This study investigated whether artificial manipulation of the byssus (via trimming) could stimulate thread production and promote shedding in adult P. penguin from two size groups. Byssal threads attached to the substrate were trimmed every 3–5 days over a 30-day period and compared to untrimmed controls. Oysters with trimmed byssus produced significantly more threads, with smaller individuals outperforming larger ones in both thread count and byssal stalk diameter. Moreover, small oysters exhibited a higher frequency of complete byssal shedding. These findings suggest that trimming stimulates thread production and accelerates stalk thickening, potentially triggering shedding due to spatial constraints at the attachment site. This response appears to reflect an adaptive mechanism for maintaining effective attachment and may help explain how mechanical or environmental cues influence byssal dynamics. Understanding this process offers new insight into the behavioral and physiological plasticity of P. penguin, with potential applications in pearl oyster management and aquaculture.

Pterophyllum scalare is a popular ornamental fish species, but current rearing methods result in high mortality, low fertility, disease incidence, and slow growth in aquarium conditions. Research on co-feeding for ornamental fish at the juvenile or adult stage needs to be completed. This study implemented a “snacking” feeding strategy using Artemia sp. to evaluate changes in fish survival rate, growth performance, and enzyme activity related to digestion, antioxidants, and immunity in a recirculating aquaculture system. Two feeding strategies were tested: one group was fed a commercial diet plus Artemia sp. (0.1% of diet) as “snacking,” and another group was fed only the commercial diet as normal. “Snacking” with Artemia sp. enhanced fish’s survival and growth performance, with higher relative weight rate, standard length, and total length than the control group. Specific growth rates for weight, standard length, and total length were also more significant in the supplemented group compared to the control group. The activity of amylase, superoxide dismutase, and glutathione peroxidase was substantially higher in the supplemented group. Adding Artemia sp. as a supplement under a “snacking” feeding strategy to the control diet was beneficial for P. scalare juvenile rearing and can guide managing recirculating farming activities.

The diurnal and nocturnal valve gaping behavior of the pearl oyster Pteria penguin was characterized through video analysis aided by open-source software. Juvenile pearl oysters were video-recorded for 48 hours under laboratory conditions, using commonly used surveillance hardware. The direct measuring of the distance changes between the two valve edges effectively revealed the pearl oysters’ tendency to open their valves wider at night-time, than during day-time. Moreover, the differences observed were also attained at the individual level. The description for the first time of this behavior has broader implications for the research in pearl oyster aquaculture. Moreover, it introduces a non-invasive tool for comprehensive assessment of adult oyster behavior.