Bioluminescence is widespread in the deep sea. In this study, the density of bioluminescent zooplankton (BL) in the deep Mediterranean Sea (MS) and at the Mid- Atlantic Ridge (MAR) was measured using low light video cameras, including a novel Image intensified Charge coupled device for Deep-sea research (ICDeep). Sampling across the MS was undertaken to assess the potential optical interference from bioluminescent zooplankton at sites under consideration for the construction of a large volume deep-sea neutrino telescope. This revealed a general decrease in deep pelagic BL densities from the western to the eastern MS. Deep mesopelagic (500- 1000 m depth) BL density was significantly correlated (p<O.Ol) to Chlorophyll a concentrations in overlying surface waters. Investigation of temporal variation across the Ionian Sea revealed a deep (500-2400 m depth) peak in BL density on the western side, present in the autumn (mean BL density: 14.92 m-3) and absent the following spring (4.52 rrr"). Deep water of Adriatic origin flows into this region and may seasonally affect the supply of organic material, increasing deep zooplankton populations. Near-bed (0-400 m above bed, mab) BL density in the MS was found to decrease exponentially with seafloor depth; by a factor of 4.2 every 1000 m. BL densities were consistently lower in the MS than at the MAR. On the MAR, at ca. 2500 m depth, an investigation of altitude effects within the near seafloor region revealed a weak increase (0.016 m-3 mab': p<O.OOl) in BL and inacroparticle (>430 urn] densities from 100 to 5 mab attwo sites south of the Charlie-Gibbs Fracture Zone. At 2500 m depth on the MAR, a rate of naturally occurring bioluminescent events was observed to be 155 times higher (3.1 min+) than literature based predictions, prompting a reappraisal of the visual environment in relation to complex topography of the deep-sea floor.

University of Macau / Faculty of Science and Technology / Department of Electromechanical Engineering

Recreational SCUBA diving has grown tremendously along most of the southern Mozambican coastline in the last eight years. This growth was not accompanied with management actions, largely due to a lack of baseline information and appropriate regulations. A number of aspects of the industry were thus covered in this study to redress this shortfall. Information was collected on divers and diving pressure in southern Mozambique using questionnaires and dive log sheets distributed through local dive centres. The diving pressure was estimated at 42 500 dives in 2001 and 62 000 dives in 2002, and occurs at about 20 dive sites. More than 50% of the diving occurs on five reefs, three of which were included in the study. Surveys using visual techniques were conducted on six reefs subjected to different diving pressures, ranging from minimal ( 6 000 dives.year-I). Divers visiting southern Mozambique were found to be mostly educated South African males in their 30s. They are experienced and committed divers, satisfied with their diving experiences in the area and sensitive to reef conservation issues. The reefs differed in benthic composition, with three mam reef groups identified through multivariate analysis. All were typified by prolific soft corals but one included an abundance of branching Acropora and the other an abundance of foliose hard corals, thus differentiating the three groups. Reef fish communities also differed among the reefs. While prey species diversity was generally similar on all the reefs, two included high densities of piscivorous species. The present levels of SCUBA diving appeared to be having no deleterious effects on the reef communities, especially when compared to other disturbances such as storms and fishing. The sustainable diving capacity was estimated to be 7000 dives/year/dive site. The overall effects of recreational diving activities in southern Mozambique are discussed, along with future research needs and the management implications of the study. / Thesis (M.Sc.)-University of Natal, Durban, 2003.