No abstract

In December 2019, a novel coronavirus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) outbreak was reported for the first time in Wuhan, Hubei province, China. This coronavirus has been referred as Coronavirus Disease 2019 or COVID-19 by World Health Organization (WHO). The spread of COVID-19 has become unstoppable, infecting around 93.5 million people worldwide, with the infections and deaths still increasing. Today, the entire planet has changed due to the greatest threat on the planet since the introduction of this lethal disease. This pandemic has left the world in turmoil and various measures have been taken by many countries including movement control order or lockdown, to slow down or mitigate the infection. Since the lockdown has been implemented almost in all affected countries, there has been a significant reduction in anthropogenic activity, including a reduction in industrial operations, vehicle numbers, and marine-related activities. All of these changes have also led to some unexpected environmental consequences. As a result of this lockdown, it had a positive and negative impact on the environment including the aquatic environment. Hence this review will therefore focus on the good and bad perspectives of the lockdown toward the aquatic environment.

The study was conducted to investigate the organ-specific antioxidants and protein damages responses in Lates calcarifer inhabiting different aquaculture farms that susceptible to different threat of pollutions. Enzymes at the front line of antioxidant system superoxidase dismutase (SOD) and catalase (CAT) evidenced to work together but respond differently in different body compartment. High SOD responses were followed with lower CAT responses observed in muscle (p < 0.05) with opposite responses exhibited by both gill and liver. The responses of SOD and CAT in muscle also showed a significant strong correlation to each other (Setiu Wetland: 0.91, Semerak: 0.79) (p < 0.01). The glutathione-dependent enzymes, glutathione-s-transferase (GST) and glutathione reductase (GR) in body compartments responded with a strong correlation to each other especially in muscle (Tumpat; muscle: 0.89, gill: 0.95 and liver: 0.54 (p < 0.01, p < 0.05), (Setiu Wetland; muscle: 0.72 (p < 0.01) and Semerak; muscle: 0.79 (p < 0.01). Opposite results were found for both protein damages biomarkers, thiols (-SH-) and carbonyl (-CH-) in comparison to biomarkers responses. In contrary to (-SH-) inconsistent results were observed for the (-CH-) with muscle found to be most oxidised. The responses of SOD, CAT, GST, GR, thiols and carbonyl were all computed into the same scale through Integrated Biomarker Score (IBR) to classify each aquaculture farms based on biomarkers responses. There was a slight variation in deviation score (A) between organs within the range of (5-7). However, Tumpat overall showed the highest IBR score and significantly higher (p < 0.05) than Setiu Wetland with a total score of combining responses score in all three organs (IBR: 84, muscle: 31, gill: 24, and liver: 29) followed by intermediate score in Semerak (IBR: 72, muscle: 23, gill: 23 and liver: 26) and Setiu Wetland (IBR: 59, muscle: 18, gill: 23 and liver: 18). These results indicated that the responses of antioxidant enzymes and protein damages in L.calcarifer from different organs are heterogeneous. Therefore, biomarkers should be selected based on their sequential groups in the antioxidant system for a better explanation of the oxidative stress evaluation in fish.

Development and urbanization processes around Terengganu River estuary are expected to release a significant amount of heavy metals into the existing bottom sediment. However, information on how and why these metals are attached into specific fraction of sediments is still lacking. Therefore, this study aimed to explain the heavy metal concentration distribution in each available fraction at Terengganu River estuary. In this study, nine surface sediments originated from various human activities area in Terengganu River estuary were collected during four different sampling sessions in 2017. Heavy metal content from the collected sediments were extracted using 3-steps BCR sequential extraction method followed by detection using Inductively Coupled Plasma Mass-Spectrometer (ICP-MS) and we discovered that the total concentration of Arsenic (As), Cobalt (Co), Copper (Cu), and Zinc (Zn) ranged from 2.18 to 17.48 mg/kg dry wt., 2.53 to 20.53 mg/kg dry wt., 1.01 to 13.13 mg/kg dry wt., and 6.10 to 65.71 mg/kg dry wt., respectively. Dominance of metals in each fraction can be arranged as follows: As: residual > reducible > exchangeable > oxidizable; Co: residual > exchangeable > reducible > oxidizable; Cu: residual > oxidizable > reducible > exchangeable; Zn: residual > exchangeable > reducible > oxidizable. Availability of metals in sediment at Terengganu River estuary is limited since that majority of metals resides in non-mobilisable fraction of the sediment. In essence, sequential extraction provides information regarding the metals’ fractionation, availability and mobility, which could be used in assessing the environmental contamination in the area.