Introduction

Tarakan City spans an area of 657.33 km², of which 61.8% or approximately 406.53 km² consists of marine waters, offering substantial potential for the development of marine and fisheries sectors (1). In addition to its marine territory, Tarakan also supports traditional aquaculture practices, particularly black tiger shrimp (Penaeus monodon) farming, through coastal pond systems, with production increasing by 175% from 2018 to 2022 (2). Pond-based aquaculture utilizes coastal areas to rear aquatic organisms within artificially or naturally formed enclosures, typically ranging from 1 to 2 hectares in size (3). These systems may be seasonal or permanent and play a dual role by supporting the aquatic ecosystem while contributing significantly to coastal community incomes, employment opportunities, and national economic growth (4).

The success of pond aquaculture is strongly influenced by environmental factors, especially water quality, which is considered a critical determinant for sustainable operations (5-7). Inadequate water conditions can lead to outbreaks of pests and diseases, which are commonly linked to environmental stressors. Water quality varies between ponds due to differences in site characteristics and surrounding influences, such as agricultural runoff, residential areas, mangrove coverage, and estuarine proximity. Among the key water quality parameters, minerals although required in small amounts play a crucial role (8, 9).

Minerals are essential for crustaceans like shrimp, contributing to basal metabolism, growth, and immune function. In addition to dietary sources, shrimp actively absorb minerals from the surrounding water (10). Adequate mineral availability in pond water has been shown to improve shrimp survival rates and growth performance. Balanced mineral ratios, such as sodium to potassium (Na/K) and magnesium to calcium (Mg/Ca), also positively affect shrimp development (11). Furthermore, minerals are vital during larval stages, molting processes, and biomass accumulation, as well as in enhancing immune responses. Despite their importance, data on water quality and mineral content in aquaculture ponds, especially in North Kalimantan, remain scarce. This study aims to assess essential mineral availability in shrimp ponds and examine their potential relationship with cultivation success (12).

Methodology

Time and Location of the Study

This research was conducted from April to July 2022, with sample collection carried out at traditional black tiger shrimp (Penaeus monodon) aquaculture ponds located in Tarakan City, North Kalimantan Province. Laboratory analysis of the samples was performed at the Nutrition Laboratory, 2nd Floor, Faculty of Fisheries and Marine Sciences, Borneo Tarakan University. The study site consisted of an extensive aquaculture pond system, managed with minimal human intervention and reliant on natural environmental conditions, without artificial aeration or supplemental feed, and featuring a single water inlet (13)The pond spanned an area of approximately 7 hectares, with post-larvae (PL) shrimp stocked at densities ranging from 4 to 70 individuals per square meter. At the time of the study, the shrimp had been stocked at the PL-20 stage and had reached 16 days post-stocking(14). The study included two pond locations categorized by their proximity to environmental influences: K1 (located less than 500 meters from an agricultural area) and K2 (located less than 500 meters from a residential area). For comprehensive sampling, each pond was sampled at three distinct points: the inlet gate, the left side, and the right side of the pond.

Materials and Equipment

The equipment utilized in this study included sample bottles, a pH meter, a dissolved oxygen (DO) meter, a thermometer, a volumetric pipette, and a refractometer. The materials used comprised pond water samples, distilled water (aquadest), and a test kit for water quality analysis.

Research Procedure

The research procedure involved several key stages, including site selection of the shrimp ponds, determination of sampling points, sample testing, data collection, and data analysis.

Sampling Method

Pond water samples were collected over a three-month period, starting from the stocking phase up to the harvest stage. Sampling was carried out twice per month, with triplicate samples taken during each session to improve data reliability. All water samples were placed in sterile containers and stored in a refrigerator to preserve their integrity before being transported to the laboratory for analysis. Sampling was conducted with a clear layout of points to ensure representativeness, as explained below.

Sample Collection

The sampling method employed in this study was purposive sampling, a technique based on deliberate selection in which samples are chosen to represent the pond area effectively. Sampling points were divided into three locations according to pond size: point 1 at the inlet gate, point 2 on the left side of the pond, and point 3 on the right side. After collection, water samples were stored in an ice box to preserve their quality prior to laboratory analysis.

Sample Analysis

The samples stored in the refrigerator were subsequently transported to the laboratory at Borneo Tarakan University for further analysis. The tests conducted included measurements of mineral content, specifically magnesium, calcium, and iron. Each was tested using a water quality test kit to determine its concentration.

Data Collection

Data collection in this study was carried out through direct field observations and water sample collection, which were later analyzed in the Laboratory of the Faculty of Fisheries and Marine Sciences, Borneo Tarakan University. The parameters measured in situ at the research site, based on the method proposed by Sustianti et al. (2014), included water temperature measured with a thermometer, salinity using a refractometer, water pH with pH paper, and dissolved oxygen (DO) using a DO meter  (15).

Data Analysis

The data analysis was conducted descriptively and comparatively by comparing the concentrations of minerals (Mg, Ca, Fe) and water quality parameters (temperature, pH, salinity, and dissolved oxygen) to established suitability standards for black tiger shrimp farming. Additionally, patterns between water quality parameters and mineral concentrations were examined descriptively across time points. Since no formal statistical tests were performed, statements such as “no significant correlation” are based on visual trend interpretation, not on inferential statistics.

To improve data reliability, each water sampling session was conducted in triplicate. These replicates helped reduce the impact of outliers and measurement error, allowing for a more accurate estimation of average values.

Results

This study was conducted in Tarakan City, North Kalimantan, to analyze the mineral content in traditional black tiger shrimp (Penaeus monodon) ponds. The study took place in two locations: Pond 1 in West Tarakan and Pond 2 in East Tarakan. Sampling was performed at three distinct points per pond (inlet, left embankment, right embankment), and results were assessed based on Indonesian water quality standards (SNI 06-2412-1991 and PP No. 22 of 2021). The results of the mineral content analysis (magnesium, calcium, iron) can be found in Table 1.

Table 1 shows mineral concentrations in Pond 1, which remained relatively stable over the eight-week period. Instead of repeating exact values, the focus here is on observed trends. Magnesium and calcium levels exhibited slight fluctuations but stayed within safe and recommended ranges. Iron was consistently undetectable, indicating minimal risk of toxicity. These patterns suggest that the pond environment maintained stable mineral availability suitable for shrimp cultivation.

In Pond 2, mineral concentrations varied more than in Pond 1, especially for magnesium (see Table 2). A noticeable increase was observed in week 6, followed by a decline toward week 10. However, these fluctuations still remained within tolerable ranges. Calcium levels showed mild inconsistency, while iron was again consistently below detection limits. Pond 2 yielded no harvest, even though both mineral and water quality parameters were within acceptable ranges. The pond owner suspected early-stage["Table", "Table 1. Mineral concentrations during the grow-out period of Penaeus monodon in Pond 1.", "8pt", "1", "false"] ["Table", "Table 2. Mineral concentrations during the grow-out period of Penaeus monodon in Pond 2.", "8pt", "1", "false"]predation as the main cause, since no mass mortality or disease outbreak was observed during the study. In contrast, Pond 1 yielded a successful shrimp harvest of 90 kg (size 35), with a survival rate of 90% from 3,000 stocked individuals. The consistent mineral profile in Pond 1, combined with good water quality, may have contributed to optimal growth and low mortality during the grow-out period. These interpretations are based on descriptive trend analysis, as no formal statistical tests were conducted in this study.

While both ponds had mineral and water quality parameters within acceptable limits, Pond 1 showed greater stability in mineral concentrations and yielded a successful harvest of 90 kg with 90% survival. In contrast, Pond 2 exhibited greater fluctuations in magnesium levels and no harvest was recorded, likely due to predation. These differences highlight the role of mineral stability and external ecological factors in farming success.

["Table", "Table 3. The role and benefits of minerals in shrimp cultivation.", "8pt", "1", "false"] ["Table", "Tabel 4. Water quality data of Pond 1 and Pond 2.", "8pt", "1", "false"]