Program

Heavy metals like cadmium (Cd) cannot be degraded and bio-accumulates into the food chain. Efficient and cost-effective methods to remove this heavy metal from the seawater are currently being studied including the use of microalgae. This study aims to assess the efficiency of live microalga Tetraselmis tetrathele as a bioremediation agent against cadmium-contaminated seawater. The microalgae were initially exposed to 0, 0.1, 0.3, 0.5, 1.0, 2.0, 3.0, 4.0 and 5.0 mg L^-1 Cd. The effective concentration affecting 50% mortality of the culture (EC₅₀) was 3.73±2.0 mg L^-1 after 120h. Results showed that T. tetrathele could survive with Cd even up to 5.0 mg L^-1 for 120h, thus this concentration was used in the remediation study. Using the data obtained by photometry together with the positive and negative controls, the cadmium removed was calculated through Langmuir equation. The maximum absorbed Cd (q_e) that reached equilibrium was 0.96±0.32 mg L^-1 or 19% of the added Cd between 12 to 36h and the remaining metal in the solution (C_e) was 1.22±0.00 mg L^-1. Most of the lead uptake was intracellular while only 0.03±0.00 mg L^-1 was adsorbed onto the cellular surfaces. Algal growth rate and chlorophyll a significantly decreased during lead exposure but algal cell sizes were not affected. Positive correlations occurred between Cd removal and the pH level in the system. It is concluded that live T. tetrathele is capable of removing Cd from seawater at the measured rate in this study.

Research on a simple mussel biomarker, Perna viridis, was conducted to detect the toxicity of Lead under different pH in laboratory study. This research was performed by exposing green mussels with a serial dilution of lead (Pb) concentration which was 0,008; 0.08; 0.8 mg/l and control combined with variations of pH which was 6.2; 7.7 and 8.2. The exposure period was 96 hours. To determine the differences in treatment and interaction among the treatments factorial ANOVA was used. The results demonstrated that the simple biomarker, condition index (CI), could statistically detect the effect of pH on Pb toxicity at concentration 0.8 mg/l for 96 h exposure under pH 8.2. Evidence supported by other biomarker i.e hemocyte classification based on color and the typical hematological staining and Ca concentration analysis in green mussel’s shell. The potential using of this simple biomarker for categorizing pollutant status in marine ecosystem is discussed.

This study is the first to report sound production in Japanese medaka (Oryzias latipes). Sound production was affected by exposure to the carbamate insecticide (aldicarb) and heavy-metal compound (copper sulfate). Medaka were exposed at four concentrations (aldicarb: 0, 0.25, 0.5, and 1 mg L−1; copper sulfate: 0, 0.5, 1, and 2 mg L−1), and sound characteristics were monitored for 5 h after exposure. We observed constant average interpulse intervals (approx 0.2 s) in all test groups before exposure, and in the control groups throughout the experiment. The average interpulse interval became significantly longer during the recording periods after 50 min of exposure to aldicarb, and reached a length of more than 0.3 s during the recording periods after 120 min exposure. Most medaka fish stopped to produce sound after 50 min of exposure to copper sulfate at 1 and 2 mg L−1, resulting in significantly declined number of sound pulses and pulse groups. Relative shortened interpulse intervals of sound were occasionally observed in medaka fish exposed to 0.5 mg L−1 copper sulfate. These alternations in sound characteristics due to toxicants exposure suggested that they might impair acoustic communication of medaka fish, which may be important for their reproduction and survival. Our results suggested that using acoustic changes of medaka has potential to monitor precipitate water pollutions, such as intentional poisoning or accidental leakage of industrial waste.

Super-intensive shrimp farming with high stocking density in a small concrete pond has been developing in Indonesia to increase production. However, the deterioration of surrounding environmental qualities relating to shrimp pond effluent is still a drawback. This study aimed at analyzing nutrient characteristics and nutrient loading of the super-intensive Lithopenaeus vannamei shrimp ponds. Three of 1000 m² full concrete ponds with pond water levels of 1.75 to 1.90 m were stocked with three differents density 750 (Pond A), 1000 (Pond B) and 1250 ind/m2 (Pond C) of the L. vannamei post larvae and reared for three months. Daily water exchanges were started at 30 days after stocking by exchanging water at level of 5 to 10 cm of pond waters, followed by a fortnightly ponds wastewater collection. Shrimp productions were in line with stocking density which were 7,862 (Pond A); 10,699 (Pond B) and 12,163 kg/pond (Pond C). However, Feed Conversion Ratio (FCR) were various for pond A,B, C at 1.40; 1.36 and 1.55, respectively. The nutrients loaded by pond B were 41.48 g TN/kg shrimp; 14.28 g TP/kg shrimp and 112.21 g TOC/kg shrimp lower compared to Pond A and B (45.22 g TN/kg shrimp; 14.85 g TP/kg shrimp and 117.03 g TOC/kg shrimp) and (53.73 g TN/kg shrimp; 16.68 g TP/kg shrimp and 132.70 g TOC/kg shrimp), respectively. Concentrations of Total Ammonia Nitrogen (TAN), Total Suspended Solids (TSS) and phosphate (PO4) discharged from all ponds exceeded the regulated concentrations of nutrients in shrimp pond effluent which was 6.9±3.7; 924±606 and 9.2±7.1 mg/L, respectively, for Pond A, 6.0±2.7; 7.98±407 and 7.9±4.0 mg/L, respectively for Pond B and 10.0±8.0; 918±660 and 11.9±7.7 mg/L, respectively for Pond C). This finding showed that wastewater discharged from super-intensive shrimp ponds should be treated to reduce concentrations of nutrients in effluent before being released to the surrounding waters.

Our pelagic microplastic surveys in the past eight years uncovered that the East Asian seas should be recognized as a hotspot of the marine plastic pollution. In addition, the transoceanic survey across the Southern Ocean, the South Pacific, and the North Pacific in 2016 raises a concern about the widespread nature of marine plastic pollution, indicating that plastic-free ocean environments are increasing rare. One of the most important topic in microplastic research to date is to harmonize/standardize the procedures for collecting and analyzing this novel oceanic pollutant. Furthermore, numerical modeling of microplastic transport is critical to predict the future abundance of microplastics in nature, although establishing the models capable of predicting the future marine plastic pollution is no doubt a tough challenge in the physical oceanography. In addition to the transport owing to ocean currents and wind waves, the transport models should include “sink terms” such as settling to deep layers by biofouling, exchanging between beaches and surf zones, ingesting by marine organisms. Furthermore, the generating process of microplastics on beaches should be explored.

There is growing evidence that microplastics (synthetic plastic particles < 5 mm in size) are accumulating in both marine and freshwater environments and that they pose a threat to aquatic organisms, ecosystems and human health. Microplastics are complex mixtures of chemicals (polymers, additives and chemicals absorbed from seawater), many of which possess endocrine disrupting or other toxic activity. Because their size range overlaps with that of many organisms at the base of aquatic food webs, the ingested microplastics and associated chemicals may be transferred up the food webs where they may cause harmful effects.
Microplastics have been detected in the guts or tissues of an increasing number of species, including fish, molluscs and crustaceans (species for human consumption) as well as other consumers in the aquatic food web. Laboratory studies have demonstrated that microplastics can reduce reproductive output and fitness in aquatic species by altering their food consumption and energy allocation. In addition, microplastic debris may host and distribute (non-) indigenous species including pathogenic microbes (e.g. Vibrio bacteria) and consequently may interrupt ecological connectivity and impact population sizes and dispersion of species. Many of these species are important to fisheries, and play a vital role in ecosystem functioning.
Here, I will present a brief overview of the physical, chemical and microbial effects of microplastics on aquatic biota and ecosystems. This will be extended by additional research results from our own group including: microplastic baseline surveys in environmental samples, fish and invertebrates from the NE Atlantic and Dutch coastal and freshwater environments; laboratory experiments with microalgae and crustaceans, and a modeling approach to estimate the impacts on productivity at marine ecosystem level. Special attention will be given to the potential human health risks from microplastics via sea food consumption.

Marine debris is already known as major environmental problems in coastal area. The beautiful Kuta Beach, Bali Island is facing the marine debris problem annually in December till March during northwest monsoon where the strong northwest wind prevails. Field observation on litter marine debris showed that the marine plastic was the dominant debris. Numerical model was used to simulate current circulation in Bali Strait and floating marine debris trajectory around Kuta Beach at the begin and end of northwest monsoon 2011-2012. Five point sources in Jembrana, Tabanan, and Badung were chosen and 10 particles were released from each point source. The result shows with an average current velocity of 0.025 m/s the existing marine debris in Kuta Beach originated from all of 5 point sources. Such marine debris needs 2-8 days to reach the Kuta Beach depend on the distance between the point source to Kuta Beach.