Sustainable Aquatic Research

A novel hypothesis: Could water trapped in bottles and containers affect the hydrological cycle and climate?

Erkan Can, Brian Austin — Wed, 24 Dec 2025 00:00:00 +0300

The Anthropocene marks a period where human activity dominates Earth’s climate system. Since the Industrial Revolution, fossil fuel use, deforestation, and intensive agriculture have sharply increased greenhouse gases, raising global temperatures by an average of 1.19°C between 2014 and 2024—approaching the 1.5°C threshold. Atmospheric CO₂ has climbed from ~280 to over 420 ppm, intensifying ocean acidification, sea-level rise, and ecological disruption. This study introduces a new hypothesis: that disruptions in the natural water cycle also amplify climate change. Water trapped in bottled or packaged forms weakens carbon sinks and alters hydrological circulation. Industrialization and massive plastic bottle use reinforce this effect. Thus, climate mitigation should not only reduce emissions but also restore natural water flows. Key strategies include reducing packaged water, promoting clean tap water, expanding refill stations, and improving water treatment. Furthermore, it is recommended that the
storage and circulation of bottled and packaged water be better regulated and managed to minimize disruption to the natural water cycle. Protecting water’s natural flow is crucial for maintaining global climate stability.

A Review of Marine Protected Areas and Fisheries in Colombia: Past, Present and Alternatives

Vladimir Puentes, Juana de Dios Murillo, Raúl Pardo — Wed, 24 Dec 2025 00:00:00 +0300

A review of the relationship between Marine Protected Areas (MPA) and fisheries was conducted in Colombia from different perspectives. The analysis was divided into two periods: MPAs established between 1960 and 1999, and those created between 2000 and 2023, reflecting significant contextual and legislative differences. Conflicts have persisted from the earliest MPAs to the present, often taking years to resolve. Current legislation regarding the creation and expansion of MPAs was examined within the framework of the 30x30 goal under the Global Biodiversity Framework. Each newly created or expanded MPA was assessed, revealing that technical fisheries-related technical aspects—particularly concerning the size and designated category of the MPAs—were overlooked. Biosphere Reserves (BRs) and Other Effective Area-Based Conservation Measures (OECMs) related to fisheries in marine-coastal areas were also identified and analyzed. Institutional stakeholders, sectoral interests, and the mechanisms that facilitate intersectoral and community consultation—as well as the challenges of applying them in offshore areas—were explored. The results highlight ongoing conflicts among sectors and a lack of consensus in key aspects between environmental and fisheries authorities regarding the establishment of MPAs or the implementation of sustainable fisheries measures. An innovative management approach is therefore needed to reconcile these differences and foster a mutually beneficial relationship between MPAs and fisheries. Alternatives are proposed to shift this historically antagonistic dynamic toward collaborative strategies that promote the conservation and sustainable use of fishery resources and ecosystems through an ecosystem-based and participatory management framework, including effective and realistic measures both within and beyond declared MPAs.

Assessing Growth Performance and Flesh Quality of Silver Carp (Hypophthalmichthys molitrix) with Natural Carotenoids in Feeds

Md. Mahabubur Rahman; Imon Kumar Shikdar — Wed, 24 Dec 2025 00:00:00 +0300

A feeding trial was conducted to evaluate the effects of natural pigment inclusion on the growth performance, carcass composition, carotenoid accumulation, coloration, and sensory quality of Hypophthalmichthys molitrix. Four experimental diets were prepared: a carotenoid-free control (CF) and three carotenoid-enriched diets containing 5% tomato (TEF), 5% carrot (CEF), and a mixture of 2.5% tomato and 2.5% carrot (TCEF). Fish were assigned to four treatments with triplicate groups and fed twice daily to apparent satiation for 90 days. Growth indices, including mean weight gain (MWG), specific growth rate (SGR), feed conversion ratio (FCR), and survival rate, were determined using standard formulas, and proximate composition, carotenoid concentration, and palatability attributes (flavor, taste, texture) were analyzed through established procedures.The TCEF-fed fish showed significantly (p<0.05) superior MWG and SGR values and a reduced FCR compared with other treatments. No significant (p>0.05) changes were found in the proximate composition among the test groups. The highest carotenoid deposition occurred in fish fed the CEF diet, followed by TCEF and TEF. Fish receiving carotenoid-enriched diets (CEF and TCEF) exhibited significantly (p<0.05) enhanced lightness (L*), redness (a*), yellowness (b*), and chroma (C*) values. Palatability evaluation revealed a strong preference for TCEF, whereas CF scored the lowest. Furthermore, TCEF proved to be the most cost-efficient diet. The results demonstrate that the combined inclusion of 2.5% tomato and 2.5% carrot effectively enhances growth, coloration, and sensory quality in H. molitrix.

Assessment of coliforms and bacterial loads associated with skin, gills, intestines, and muscles of five species of grouper

Ahmed Al-Harbi, Abdulmohsen Al-Asous — Wed, 24 Dec 2025 00:00:00 +0300

This study was conducted to determine the total coliform (TC), and fecal coliform (FC) counts and bacterial loads of the skin, gills, intestines, and muscles of grouper, ariolated grouper (Epinephelus areolatus), orange-spotted grouper (Epinephelus coioides), coral trout (Plectropomus areolatus), roving coral grouper (Plectropomus pessuliferus), and moontail seabass (Variola louti). The aerobic bacterial counts of the groupers' skin, gill, intestine, and muscle samples ranged from 9.04 ± 0.14 to 11.57 ± 0.82, 7.69 ± 0.89 to 11.51 ± 0.51, 7.49 ± 0.14 to 11.54 ± 0.41, and 4.41 ± 0.49 to 4.64 ± 0.35 log CFU/g, respectively. The total coliform counts were presented in skin with the values of 1100 MPN/g, while in gills and in intestines the values ranged from 460 to 1100 MPN/g and 240 to 460MPN/g, respectively. The fecal coliform counts were found in skin and gill samples, with the values ranged from 150 to 240 MPN/g and 64 to 150 MPN/g, respectively. In contrast, the total coliform and fecal coliform counts were not detected in all the groupers' muscle samples.

Oxidative Stress Responses in Chlorella vulgaris Following Chlorpyrifos Exposure

Wed, 24 Dec 2025 00:00:00 +0300

Chlorpyrifos (CPF), a widely used organophosphate pesticide, frequently enters aquatic environments and poses potential risks to non-target primary producers such as microalgae. This study investigated the oxidative stress response of Chlorella vulgaris exposed to sublethal concentrations of CPF based on the 96-h EC₅₀ value (4.86 mg/L). Experimental groups were designed using 1/8, 1/4, and 1/2 EC₅₀ concentrations, and biochemical responses were evaluated at 24, 48, 72, 96, and 120 hours. Results demonstrated that CPF exposure induced significant changes in antioxidant enzyme activities. Superoxide dismutase (SOD) and catalase (CAT) activities increased at specific exposure periods, while glutathione peroxidase (GPx) exhibited concentration- and time-dependent alterations. Glutathione (GSH) levels increased throughout exposure and during the elimination phase, indicating activation of non-enzymatic antioxidant defense. In contrast, thiobarbituric acid reactive substances (TBARS), an indicator of lipid peroxidation, showed no statistically significant change.

The distribution of the potentially harmful dinoflagellate species Polykrikos hartmannii W.M.Zimmermann 1930 in the İzmir Bay

Levent Yurga — Wed, 24 Dec 2025 00:00:00 +0300

This study investigated the status of Polykrikos hartmannii, a dinoflagellate species with the ability to cause excessive blooms, in the İzmir Bay between 2022 and 2025. Previously reported in the Black Sea and the Sea of Marmara, the species began to be seen in the İzmir Bay in 2022. It began to bloom in the spring of 2023, and between September and November of the same year, it proliferated to the point of covering the entire bay in a brown-red color, attracting the attention of local authorities and scientists. The species, which has also been encountered in monitoring studies conducted in the bay for the last three years, exhibited excessive blooms, particularly in November 2023, and was detected at concentrations of 12.58 × 10⁶ cells L⁻¹ at station 8 and 8.86 × 10⁶ cells L⁻¹ at station 9. It is thought that the species, which reproduced so excessively that it covered the entire İzmir bay between 2023 and 2024, was most likely transported to the bay via ballast tanks.

Molecular Characterization and Antibiotic Resistance Profiling of Bacteria Associated with Clarias gariepinus from selected fish farms in Ota, Nigeria

Wed, 24 Dec 2025 00:00:00 +0300

Antibiotic resistance of genetically diverse bacteria is of high implication for fish farming and human consumption. The present study evaluates the genetic diversity and antibiotic resistance profile of bacteria pathogens isolated from Clarias gariepinus in aquaculture farms. Bacteria were isolated from C. gariepinus (n=15), and identified using biochemical methods, and antimicrobial susceptibility test was performed. Multiple antibacterial resistance index (MARI) was determined and isolates with multidrug resistance (MDR) pattern were genotyped and sequenced for 16sRNA and further determined for genetic diversity. Of the fifty bacteria, Vibrio species (30%), Escherichia coli (14%), S. aureus (12%), Proteus spp (12%), Salmonella and Shigella spp (8%), Micrococcus luteus (6%), Bacillus spp (4%), Klebsiella aerogenes (4%), and P. aeruginosa (2%) were observed. All the bacteria isolates showed resistance were generally resistant to several other antibiotics: Impenem, Cefuroxim, Ofloxacin, Augmentin, Cefexime, Cefotaxin, Ciprofloxacin, Ampiclox, Nitrofuranton, and Nalidixic acid while only few bacteria showed intermediate sensitivity. Genetically, diverse multidrug resistance bacteria is a worrisome concern in aquaculture industry and regular surveillance and regulation of antibiotics would ensure sustainable fish production, and public health assurance

Optimized hydrolysis of tuna viscera by a spray-dried cell-free crude enzyme preparation from Staphylococcus sp. isolated from fermented fish

Sharon Nonato Nuñal, Jhovian Lee Joseco — Wed, 24 Dec 2025 00:00:00 +0300

Proteolytic enzymes are used to produce hydrolysates from fish processing wastes to recover protein or lipid for various applications. Tuna processing also generates these by-products which contributes to post-harvest losses and environmental pollution. Thus, this study was aimed at optimizing the proteolytic activity on yellow fin tuna (Thunnus albacares) viscera (YFTV) of a spray-dried cell-free crude enzyme extracted from the culture of Staphylococcus sp. strain L1 which was isolated from fermented sardines and identified using 16s rRNA gene analysis. To prepare the enzyme, the isolate was grown in a protease-producing medium supplemented with casein and peptone. The culture supernatant was harvested following fermentation and was spray-dried. For the hydrolysis, the process was optimized to produce hydrolysates with high total soluble protein (TSP) and high degree of hydrolysis (DH). Utilizing the central composite design of the Response Surface Methodology (RSM), YFTV protein hydrolysis was conducted at varying enzyme concentrations (0.5-1.5%, w/v), temperature (40-60°C) and hydrolysis times (60 to 180min). According to the RSM-generated model, the optimal conditions for achieving the highest TSP were 60 min, 40°C and 1.5% enzyme concentration. For the highest DH, the optimal conditions were 60 min, 60°C and 0.5% enzyme concentration. The predicted optimum values using the generated linear and quadratic equations were 3.68 mg/ml TSP and 30.67% DH. The lack of fit test for both responses yielded an insignificant value (p > 0.05), indicating that the regression coefficient was adequate for estimating both responses under various conditions. The optimized protein hydrolysis conditions for YFTV using protease from Staphylococcus sp. could be effectively applied in food production systems, particularly in downstream processing. Furthermore, the utilization of tuna viscera as protein hydrolysates could substantially contribute to waste management in the processing industry.