No abstract

Length-weight relationships are presented for 35 fish species from the Badagry creek, Lagos, Nigeria. The values of the parameter b are within the expected range of 2.5-3.5. No information regarding length-weight relationships has been reported from Nigeria or documented in FishBase for 13 of the species.

Lagos, a coastal megacity with more than 11 million inhabitants faces serious development challenges in addition to climatic risks and extreme weather events. There are uncertainties about future disaster risk trends and about how to manage and adapt to existing threats in ways that ensure a just and sustainable development trajectory. In this paper, we explore the changes that have occurred in risk management in Lagos over the last 20 years, as part of a broader endeavor towards sustainability. We draw on transition theory to analyze data collected from a scenario workshop and expert interviews conducted over a period of two years, to understand the influences, processes and actors that shape the adaptationdevelopment nexus in Lagos. Findings based on stakeholders voices present a risk management regime firmly oriented towards protecting contemporary development gains and policies, despite Nigeria's contested development strategy. Future positioning of risk management is described as either maintaining its current goals or shifting towards a position where development is seen as a root cause of risk and a focus for change. Resilience (marginal changes in development to maintain stability) is not foreseen as a likely future choice for Lagos. This is in contrast to many global agendas that promote resilience and reflects the realities of managing risks in the context of contested development.

The concentrations of four heavy metals (Zn, Fe, Cu, and Pb) in water, sediment, and tissues (gill, muscle, brain, and intestine) of Oreochromis niloticus from a segment of the Lagos Lagoon complex were monitored for 10 months (July 2012-April 2013) spanning wet and dry seasons. Three sampling stations were selected: Ologe Lagoon, the nearest to the point where effluent is discharged from Agbara Industrial Estate, the Owo River is upstream before the point of discharge of industrial effluent, and Etegbin is downstream. In most cases, the highest concentrations of heavy metal in fish tissues were recorded in samples obtained from Ologe Lagoon. The ranges of concentrations of heavy metals in the tissues of the fish were 4.06 ± 2.45-49.94 ± 13.11, 81.27 ± 28.52-2044.64 ± 554.77, 10.90 ± 7.69-41.10 ± 11.24, and 0.12 ± 0.07-1.81 ± 3.12 mg/kg for Zn, Fe, Cu, and Pb, respectively. There were significant negative correlations (lowest; r = -0.24, p < 0.01, n = 30; highest; r = -0.58, p < 0.01, n = 30) between fish tissue metal concentrations and size of fish from Ologe Lagoon. Also, significant positive correlations (lowest; r = 0.48, p < 0.05, n = 30; highest; r = 0.93, p < 0.01, n = 30) between concentrations of Cu in sediment and tissues of O. niloticus were observed. The concentrations of the metals in the tissues of O. niloticus have exceeded the limits recommended by WHO. The maximum safe daily consumption (MSDC) value of Fe in Ologe Lagoon was lower than the recommended average daily intake of fish for humans. This indicated that O. niloticus from Ologe Lagoon may not be safe for human consumption. Therefore, there is a need for regular monitoring of heavy metal in these water bodies and enforcement of existing laws on the treatment of effluent before they are discharged into aquatic ecosystems.