Significant metal buildup within the organs of Lethrinus sp. and Caranx ignobilis (Forsskål 1775) from Kao Bay waters, Indonesia

Fish organs can contain heavy metals. This study’s objective was to map the distribution of heavy metals in several fish organs.. The research was conducted in Kao Bay waters from April to September 2019. The samples obtained were prepared at the aquatic science laboratory of Khairun University and were analyzed at the Environmental Productivity Laboratory of IPB University Bogor using the AAS instrument to determine heavy metals. The heavy metals accumulation in Lethrinus sp fish meat was Zn > Cu > Mn > Pb > Ni > Hg > Cd, and in gill was Zn > Pb > Mn > Ni > Hg > Cd. The accumulation of heavy metals in Caranx ignobilis fish meat was Zn > Pb > Mn > Cu > Ni > Hg > Cd, whereas the accumulation in the gills was Zn > Pb > Ni > Mn > Cd > Hg > Cu. Zn accumulation was the highest heavy metal discovered in fish as a result.


Introduction
Kao Bay Coastal is located in the North Halmahera Regency's coastal region and has abundant natural resources, both natural and artificial systems.The region's non-biological wealth is made up of a variety of minerals of great economic worth, including gold and silver.Biological resources are in the form of fish.Fisheries are considered important because fish contain high quality protein.Furthermore, fish has an important role for humans because of the presence of nutrients, minerals and vitamins [1].
Lethrinids, also known as the emperor fish family (Emperors), are coastal fish found mainly on or near coral reefs [2].L. lentjan was found to migrate throughout its life including to mangroves and seagrasses as juveniles before migrating authentically to coral reefs as adults [3].C. ignobilis has characteristics, i.e., daily weight growth of 0.267 ± 0.005 g/day, daily length growth of 0.081 ± 0.003 cm/day, and considered as a fast growth [4].These fish can tolerate temperatures between 25 and 28 °C.
The giant trevally, Caranx ignobilis )RUVVNDÛO WKH ODUJHVW ,QGR-Pacific carangid, is an apex predator reaching a maximum weight of up to 80 kg and a total length of 170 cm [5].
The existence of economic problems and industrialization resulted in water pollution in coastal areas.
Pollution generating from these activities will have a direct relationship and cause aquatic ecological patterns [6].The build-up of metal pollutants in marine fish eaten affects consumers of fish as well as the fishing sector [7].Heavy metals are also found in various waters, sediments and various other marine ecosystems [8], [9].Several studies stated that heavy metal pollution in fish will occur in the liver, kidneys, gills and muscles [10].The Mn found in the waters is due to the hydrothermal circulation [11].Mercury (Hg) is caused by the influence of natural and human activities.Furthermore, the impact of industrial activities can increase Hg levels in the waters and affect the decline in fish stocks [12].This study aimed to map the distribution of heavy metals in several fish organs.

The area of the study
This study was carried out around the Bay of Kao waters.Consideration of the research area location because there was some waste from mining.The research time was from April to September 2019.

Data gathering techniques
Primary data from fishermen were gathered for this investigation.Preliminary information, in the form of fish discovered in the wild, was collected by firsthand observations the Waters of Kao Bay.The processed samples of 10 captured fish were delivered to the Environmental Productivity Laboratory of IPB University Bogor for heavy metals analysis using the AAS Variant SpectrAA-20 after being prepared in the aquatic science lab of Khairun University.In this way, we do not sacrifice the BSC samples.The sample is an edible organism, is not protected, and consumed.Thus, ethical approval is not required for this study

Statistical analysis
To determine the differences between the heavy metals used the cluster analysis.Statistical data processing was performed using SPSS ver.15 software.

Results and analysis
Figure 2 depicts a variation in the weight of Lethrinus sp. and Caranx ignobilis fish.This size difference was due to different food, location, and age.Lethrinids had having a body length of 27.83 mm and a mass of 0.276 g [13].Caranx ignobilis weight was in the range of 213.8 ± 23.6 -181.7 ± 31.5 g in fish cages (karamba) [14].Developmental studies revealed that the spawning process occurs once a year and carnivorous feeding [6].

Concentrations of heavy metals in fish target organs
The heavy metals contents in the studied fish.Table 1 displays the number of heavy metals in each target organ.Lethrinus sp. in meat varied from 0.00 -27.33 and mg/kg measured between 0.01-46.44mg/kg.Zn, Cu, Mn, Pb, Hg, and Cd were the heavy metals that accumulated in the meat of the Parastromateus species in that order.The heavy metal Pb in the fish meat of Parastromateus sp. had surpassed the prescribed quality level based on the limit of chemical contamination in fish feeding (Table 1).When viewed from Due to the metal element's importance to fish, the amount of heavy metal Zn found was higher than that of other heavy metals metabolism regulation.Analysis of variance for Zn contents showed a significant different result (p < 0.05) both in meat and gills.The average values of As, Cd, Cr, Hg, and Pb in marine fish in the Zhejiang, China population were 0.783, 0.009, 0.114, 0.031, and 0.043 mg/kg wet weight, respectively [16].Three Weight (g) separate environmental matrices (sediment, macroalgae, and fish) were examined for Hg, Cd, Pb, and As as probable hazardous elements (PHE) [17].The concentrations of In-As revealed the following molluscan trend: Demersal > pelagic, with distinct subgroup differences.[18].
Small fish have higher safety than larger and older fish.Liver, muscle, and gonads had the first decreases in Hg content.The concentration of Hg was decreased in the order of liver, muscle, and gonads.The concentration of Hg The values in fish tissue varied from 0.016 ppm in the gonads to 0.855 ppm (mg kg-1 w/w) in the liver tissue, while they were 0.24 to 0.49 ppm (mg kg-1 w/w) in the muscle tissue [19].The liver had a high concentration of heavy metals, with Zn predominating in all three fish organs examined in Gerres abbreviatus (61.31 mg kg -1 w/w) [20].Pelagic fish (omnivores/herbivores) had higher metal concentrations than benthic fish (carnivores) [21].The existence of a long-term program is very useful in providing information for the community to assess health risks due to heavy metal pollution [22].

Conclusion
The number of heavy metals present in both types of fish had the highest Zn accumulation in Caranx ignobilis and Lethrinus sp.The highest content was found in Kao Bay, i.e., in the meat portion of 27.33 mg/kg and 21.13 mg/kg, while in the gills of 46.44 mg/kg and 53.93.Therefore, the highest accumulated part was in the gills.

Figure 1 .
Figure 1.Research locations around the Waters of Kao Bay (location = ).

Figure 2 .
Figure 2. The average weight of the research sample (n=10) in the Kao Bay Waters.

Table 1 .
The concentration of heavy metals (mg/kg) in fish tissue from Kao Bay Waters.