In this study, we examined and compared the WBR processes of B. jacksonianum, B. affinis anceps (hereafter referred to as B. anceps here), and B. diegensis. B. anceps displayed twin-body regeneration, whereas B. jacksonianum and B. diegensis regenerated only one zooid each. Histological examination confirmed the presence of multiple vesicles formed from hemoblast aggregates during WBR, a phenomenon observed in other Botrylloides spp. The investigated species exhibited strong similarities in their WBR, with some variations in the overall process, indicating the presence of similar mechanisms underlying WBR. Understanding the intricacies of tunicate WBR contributes to our knowledge of regenerative biology and may offer valuable insights for regenerative medicine research in vertebrates.
The increased illegal fishing to supply swim bladders is the current threat to the Totoaba macdonaldi, due to the high commercial value of swim bladders. Species identification is the foundation of the endangered animal protection. Limited by the sophisticated thermal cycling, specialized machine, and sequencing costs, DNA barcoding might not better satisfy the needs of on‐site inspection to the efficiency, convenience, and low cost, although it has reliable results and has been widely used. It is necessary to establish a convenient, rapid, sensitive, and accurate method for customs to inspect the swim bladders in legal or illegal trade on site. In this study, we introduce real‐time fluorescence‐based recombinase‐aided amplification (RF‐RAA) into species identification of swim bladders. Specific primers and probes targeted to Totoaba macdonaldi were designed and the reaction temperature and time were screened. It was applied to the forensic identification of swim bladders confiscated by custom after its sensitivity and specificity were verified. The results showed that (1) the primers of TMcytB F1 and TMcytB R3 targeted to the Cytb had a good amplification at 39°C, 30 cycles (15 min) with good repeatability and stability; (2) the method had good specificity and no cross‐reaction with other 22 swim bladder originated species; (3) the lowest detectable limit (LDL) of this method was 3.7 × 101 copies/μL; (4) about 1.836 kg of all the swim bladders confiscated by Shenzhen customs on 2022 were identified to be Totoaba macdonaldi by using this method. This study provides an effective species identification alternative for competent authorities to tackle the illegal import and market regulation of totoaba swim bladders.
As Fujairah comprises extremely diverse natural landscapes which enforce us to protect and understand possible risks and challenges faced by the coastal waters of Fujairah, it is critical to mitigate, reduce, and eliminate the risks. The aim of this study is to assess and evaluate the effect of such anthropogenic activities on the offshore waters of Fujairah. Accordingly, two buoys were deployed after conducting a baseline survey for 30 locations targeting areas affected by the anthropogenic activities. Furthermore, two sites were chosen for the buoy deployment, nearshore which is across the desalination plant (Qidfa) and offshore which is across the oil and gas facility port (Skamkam). After analyzing the water quality measurements taken for 1 year from both deployed buoys and compared it with the baseline survey measurements, an indication of water quality deterioration in nearshore and offshore buoys was evinced, and the nearshore site which located in Qidfa has a higher deterioration in water quality measurements compared to the offshore site located in Skamkam. A long-term monitoring program needs to be conducted to gather additional data on water quality over several years to help identify the seasonal variations, trends, and long-term changes in water quality.
Sea urchin population demographics can respond to changes in keystone species abundances, with the magnitude of these responses varying depending on environmental influences. In this study, sea urchin populations were surveyed across 15 Aleutian archipelago islands over a 30-year period to understand how patterns of sea urchin demography (density, biomass, and size structure) varied through different ecological regimes that were caused by changes in the abundance of sea otters, a keystone species in this system. To examine long-term changes in sea urchin demographics, four time periods across the recent decline of sea otters were examined: during sea otter presence (1987-1994), nearing absence at the end of the decline (1997-2000), 10 years postdecline (2008-2010), and 15-20 years following the loss of sea otters from the ecosystem (2014-2017). Our results show that when sea otters were broadly present, sea urchin demographics were generally similar across the archipelago, with few urchins that had large-sized bodies. During this time, bottom-up environmental controls were muted relative to top-down forces from keystone predation. However, as sea otters declined and remained absent from the system, abiotic factors became more influential on sea urchin biomass, density, and size structure. In particular, differences among island groups during these periods were correlated with variation in ocean temperature, bathymetric complexity, and habitat availability. Sea urchin recruitment also varied among island groups, corresponding to ecoregions delineated by oceanic passes across the archipelago. The functional extinction of sea otters revealed an increasing influence of abiotic forcing in the absence of top-down control. This study further highlights the importance of understanding how keystone predators regulate herbivore demographics.
Tissue regeneration and wound healing remain extremely understudied in elasmobranchs as many wounds are recorded through one-off opportunistic observations with an inability for long-term monitoring of individuals. This study demonstrates partial fin regeneration of a silky shark (Carcharhinus falciformis) almost one year after a traumatic injury that resulted in a 20.8% loss of the first dorsal fin. The shark was photographed 332 days after the recorded injury with a newly shaped dorsal fin that had healed to 87% of the original size. Photographs provided by divers allowed for accurate measurements of fin growth, confirming an approximate 10.7% increase in fin area, indicative of tissue regeneration. Wound healing rate was calculated to conclude that the initial wound reached complete closure by day 42, which is analogous with other elasmobranch healing rates. Prior to this study, only one other record of dorsal fin regeneration had been documented in a whale shark. This provides the first evidence of dorsal fin regeneration in a silky shark and contributes to the limited studies of wound healing rates in sharks. This newfound insight into tissue regeneration and wound healing underscores the importance of further research to understand how they respond to traumatic injury in the face of mounting environmental challenges, both natural and anthropogenic. Additionally, this study exemplifies the power of collaboration between researchers and the public, including photographers and divers, to expand the scope of research studies and bridge the gap between science and society.
