Temperature and Water Exchange in a Semi-Enclosed Lagoon, Bamburi, Kenya.

Abstract

In the context of high sea-surface temperature anomalies causing widespread coral mortality, this study investigates the heat balance of a semi-enclosed coral reef lagoon system and any additional contribution of UV radiation as a trigger for bleaching. The study lagoon is situated north of Mombasa Island, along the Nyali- Bamburi-Shanzu coastline, at 4o0’01" S, 39o0’44" E (Figure 1) and has a surface area of 3.75 km2 and 12.5 km2 during spring low and high tides respectively. It consists of three topographic features: the shallow back-reef lagoon, the 300 m wide, 7.5 km long reef crest that is exposed during low tide and shelters the lagoon from oceanic swells and the relatively deep central longitudinal channel that collects all lagoon water at spring low tide. The mean depth of the lagoon does not exceed 0.7 m and the width varies between 1.5 km and 2.0 km at MSL. The main channel system connects the lagoon southwards to Nyali lagoon through a 250 m wide, 5.8 m deep point. Towards the northern end of the lagoon is a shallower (2.5 m) channel system connecting the lagoon to the mouth of Mtwapa creek (Kirugara et al., 1998).