Shelflife of whole fresh Lake Malawi tilapia (Oreochromis species – Chambo) stored in ice

Lake Malawi Tilapia (chambo) fish species is widely consumed and forms the most important commercial fishery in Lake Malawi. However, as a highly perishable commodity, knowledge regarding how long fresh fish would remain in acceptable and safe condition in storage is indispensable for consumers and processors. Presently, no such information exists for the Lake Malawi Tilapia in Malawi. A study was therefore conducted to estimate shelflife of whole fresh Lake Malawi Tilapia stored in ice (0oC) for 21 days. Sensory, microbiological and pH analyses were conducted to describe changes in quality and freshness of the fish with storage time in ice. Shelflife of the fish was estimated between 16 and 18 days. A strong linear correlation (R2=0.95) was observed between sensory demerit scores and storage time in ice. Total bacteria viable counts and pH at the time of sensory rejection of the fish were 1.6×107 cfu/g/cm2 and5.84 respectively. Pseudomonas and Micrococcus bacteria were found in relatively high numbers throughout the storage period. The study demonstrated that like other tropical fish, Lake Malawi Tilapia has a relatively longer shelflife. The long storage life in ice of Lake Malawi Tilapia is advantageous to most small scale fresh fish sellers and processors especially from rural areas in Malawi who solely depend on ice as a sole and affordable way of preserving fresh fish.Key words: Shelflife, Tilapia, ice storag

Assessment of apparent effectiveness of chemical egg disinfectants for improved artificial hatching in oreochromis karongae (pisces: cichlidae)

Oreochromis karongae is one of the three key Tilapia species locally known as ‘Chambo’ which is endemic to Lake Malawi. The species is favored by consumers and due to high demand its catches have significantly declined over time. Aquaculture holds the potential to supplement catches as well as produce seed for restocking purposes. However, seed production of O.karongae in artificial hatcheries has registered little success due to high egg and fry mortalities. Therefore, a study was conducted to compare the apparent effectiveness of three chemical egg disinfectants in an attempt to improve hatching success and reduce fry mortality in O. karongae in an artificial re-circulating incubation system at the National Aquaculture Center, Domasi, Malawi. Batches of 200 stage II eggs were immersed for 5 minutes in 50ml solutions of (1) 50mg/l Potassium Permanganate, (2) 500mg/l Formalin, (3) 1000mg/l Sodium Chloride, (4) 5000mg/l Sodium Chloride, while treatment (5) was a control without any chemical treatment. Each treatment was replicated three times in 1.2 L plastic incubation jars with continuous water flow rate of 0.17 l/s operated at 10% daily water replacement. There was significantly low total mortality and high hatchability in treatments (1), (2) and (3) than (4) and (5) (p<0.05). The results provided evidence that pre-incubation egg treatment using chemicals has potential to significantly reduce mortalities and increase fry production in an artificial re-circulating incubation system. It is recommended, based on the findings that lower concentrations of sodium chloride, being a safer and less toxic chemical can be used for disinfecting O.karongae eggs. Future studies should focus on undertaking a toxicity test with various levels of the chemical disinfectants to identify optimum doses. This should be coupled with microbiological assays to validate the apparent effectiveness found in this study and identify the key microbial species that are responsible for mortalities during incubation of O.karongae eggs in a re-circulating system.Key words: Egg, disinfectants, incubation, recirculation, hatchability, egg treatment, mortality, Oreochromis karonga

Urban Community Power: Enhancing Urban Forest Diversity and Reversing Ecosystem Disservices in Zomba City, Malawi

Tree species diversity in urban green spaces supports the provision of a wide range of urban ecosystem services, well studied in developed countries and less so in developing countries, where little is discussed concerning the role of urban communities in addressing the eminent threat facing green spaces. A study was, therefore, conducted to assess the impact of community involvement in the management of urban green spaces, which is mostly left in the hands of the central government in most developing countries. Two hills, namely, Sadzi and Chiperoni hills, were selected within Zomba city, where the latter has no community involvement in managing it. Trees with diameters at breast height (DBH) of ≥5 cm were measured and identified to species level from 25 sampled plots (20 × 20 m each). The results found a total of 51 species, 40 genera and 17 families, with the Fabaceae family dominant in both hills. A Shannon index of above 3.0 was recorded from both hills, with a greater tree density for Sadzi hill at 695 trees/ha. Sadzi hill has gained more than a twofold increase in green cover, while Chiperoni has lost 10%. Despite being in the regenerating phase, the community management is contributing to urban green space provision, ecosystem services and biodiversity conservation

Urban Community Power: Enhancing Urban Forest Diversity and Reversing Ecosystem Disservices in Zomba City, Malawi

Tree species diversity in urban green spaces supports the provision of a wide range of urban ecosystem services, well studied in developed countries and less so in developing countries, where little is discussed concerning the role of urban communities in addressing the eminent threat facing green spaces. A study was, therefore, conducted to assess the impact of community involvement in the management of urban green spaces, which is mostly left in the hands of the central government in most developing countries. Two hills, namely, Sadzi and Chiperoni hills, were selected within Zomba city, where the latter has no community involvement in managing it. Trees with diameters at breast height (DBH) of ≥5 cm were measured and identified to species level from 25 sampled plots (20 × 20 m each). The results found a total of 51 species, 40 genera and 17 families, with the Fabaceae family dominant in both hills. A Shannon index of above 3.0 was recorded from both hills, with a greater tree density for Sadzi hill at 695 trees/ha. Sadzi hill has gained more than a twofold increase in green cover, while Chiperoni has lost 10%. Despite being in the regenerating phase, the community management is contributing to urban green space provision, ecosystem services and biodiversity conservation

Complex adaptive systems-based framework for modeling the health impacts of climate change

Introduction: Climate change is a global phenomenon with far-reaching consequences, and its impact on human health is a growing concern. The intricate interplay of various factors makes it challenging to accurately predict and understand the implications of climate change on human well-being. Conventional methodologies have limitations in comprehensively addressing the complexity and nonlinearity inherent in the relationships between climate change and health outcomes. Objectives: The primary objective of this paper is to develop a robust theoretical framework that can effectively analyze and interpret the intricate web of variables influencing the human health impacts of climate change. By doing so, we aim to overcome the limitations of conventional approaches and provide a more nuanced understanding of the complex relationships involved. Furthermore, we seek to explore practical applications of this theoretical framework to enhance our ability to predict, mitigate, and adapt to the diverse health challenges posed by a changing climate. Methods: Addressing the challenges outlined in the objectives, this study introduces the Complex Adaptive Systems (CAS) framework, acknowledging its significance in capturing the nuanced dynamics of health effects linked to climate change. The research utilizes a blend of field observations, expert interviews, key informant interviews, and an extensive literature review to shape the development of the CAS framework. Results and discussion: The proposed CAS framework categorizes findings into six key sub-systems: ecological services, extreme weather, infectious diseases, food security, disaster risk management, and clinical public health. The study employs agent-based modeling, using causal loop diagrams (CLDs) tailored for each CAS sub-system. A set of identified variables is incorporated into predictive modeling to enhance the understanding of health outcomes within the CAS framework. Through a combination of theoretical development and practical application, this paper aspires to contribute valuable insights to the interdisciplinary field of climate change and health. Integrating agent-based modeling and CLDs enhances the predictive capabilities required for effective health outcome analysis in the context of climate change. Conclusion: This paper serves as a valuable resource for policymakers, researchers, and public health professionals by employing a CAS framework to understand and assess the complex network of health impacts associated with climate change. It offers insights into effective strategies for safeguarding human health amidst current and future climate challenges

Using demand mapping to assess the benefits of urban green and blue space in cities from four continents

The benefits of urban green and blue infrastructure (UGI) are widely discussed, but rarely take into account local conditions or contexts. Although assessments increasingly consider the demand for the ecosystem services that UGI provides, they tend to only map the spatial pattern of pressures such as heat, or air pollution, and lack a wider understanding of where the beneficiaries are located and who will benefit most. We assess UGI in five cities from four continents with contrasting climate, socio-political context, and size. For three example services (air pollution removal, heat mitigation, accessible greenspace), we run an assessment that takes into account spatial patterns in the socio-economic demand for ecosystem services and develops metrics that reflect local context, drawing on the principles of vulnerability assessment. Despite similar overall levels of UGI (from 35 to 50% of urban footprint), the amount of service provided differs substantially between cities. Aggregate cooling ranged from 0.44 °C (Leicester) to 0.98 °C (Medellin), while pollution removal ranged from 488 kg PM2.5/yr (Zomba) to 48,400 kg PM2.5/yr (Dhaka). Percentage population with access to nearby greenspace ranged from 82% (Dhaka) to 100% (Zomba). The spatial patterns of pressure, of ecosystem service, and of maximum benefit within a city do not necessarily match, and this has implications for planning optimum locations for UGI in cities