Anthropogenic impacts on coral reefs and their effect on fishery of Kilwa District, Tanzania

Tanzanian fishing coastal communities live on fishing activities as one their major economic activities, practicing fishing on shallow coral reefs areas whereby about 70% of fishery is artisanal. Improper use and overexploitation of fishery resources have resulted in damaging the coral reefs and the subsequent low quality catches. This study aimed at examining the impacts of coral reef fishery decline on rural livelihoods with an emphasis on food insecurity, alternative capabilities and activities on coastal communities of Kilwa district, Tanzania. Data collection methodology included household questionnaire survey, key informant interviews, participant observation and photographing. The survey was based on a sample of 90 households, randomly selected from three villages. The findings attest for a gradual reduction in fish catches over time, brought about by natural and anthropogenic impacts. Overfishing,use of illegal and destructive fishing methods, as well as extreme weather conditions, all threaten the sustainability of marine resources, particularly coral reef fishery that constitutes an important source of food and  livelihood. Following the results and as a way of lessen the current pressure on marine resources and diversifying livelihood capabilities we recommend introduction of mariculture and modern farming technologies especially on green vegetables on farms that can potentially be irrigated. The study further recommends establishment of a marine protected area and; in addition, the need to promote educational programs on  environmental and resources uses as well as application of active  restoration protocols for damaged coral reefs.Key words: Songo songo, Kivinje, Songo mnara, livelihoods, coral bleachin

Chemical potential of quasi-equilibrium magnon gas driven by pure spin current

We show experimentally that the spin current generated by the spin Hall effect drives the magnon gas in a ferromagnet into a quasi-equilibrium state that can be described by the Bose-Einstein statistics. The magnon population function is characterized either by an increased effective chemical potential or by a reduced effective temperature, depending on the spin current polarization. In the former case, the chemical potential can closely approach, at large driving currents, the lowest-energy magnon state, indicating the possibility of spin current-driven Bose-Einstein condensation

Self-recognition in corals facilitates deep-sea habitat engineering

The ability of coral reefs to engineer complex three-dimensional habitats is central to their success and the rich biodiversity they support. In tropical reefs, encrusting coralline algae bind together substrates and dead coral framework to make continuous reef structures, but beyond the photic zone, the cold-water coral Lophelia pertusa also forms large biogenic reefs, facilitated by skeletal fusion. Skeletal fusion in tropical corals can occur in closely related or juvenile individuals as a result of non-aggressive skeletal overgrowth or allogeneic tissue fusion, but contact reactions in many species result in mortality if there is no ‘self-recognition’ on a broad species level. This study reveals areas of ‘flawless’ skeletal fusion in Lophelia pertusa, potentially facilitated by allogeneic tissue fusion, are identified as having small aragonitic crystals or low levels of crystal organisation, and strong molecular bonding. Regardless of the mechanism, the recognition of ‘self’ between adjacent L. pertusa colonies leads to no observable mortality, facilitates ecosystem engineering and reduces aggression-related energetic expenditure in an environment where energy conservation is crucial. The potential for self-recognition at a species level, and subsequent skeletal fusion in framework-forming cold-water corals is an important first step in understanding their significance as ecological engineers in deep-seas worldwide

Chimerism in Wild Adult Populations of the Broadcast Spawning Coral Acropora millepora on the Great Barrier Reef

Chimeras are organisms containing tissues or cells of two or more genetically distinct individuals, and are known to exist in at least nine phyla of protists, plants, and animals. Although widespread and common in marine invertebrates, the extent of chimerism in wild populations of reef corals is unknown.The extent of chimerism was explored within two populations of a common coral, Acropora millepora, on the Great Barrier Reef, Australia, by using up to 12 polymorphic DNA microsatellite loci. At least 2% and 5% of Magnetic Island and Pelorus Island populations of A. millepora, respectively, were found to be chimeras (3% overall), based on conservative estimates. A slightly less conservative estimate indicated that 5% of colonies in each population were chimeras. These values are likely to be vast underestimates of the true extent of chimerism, as our sampling protocol was restricted to a maximum of eight branches per colony, while most colonies consist of hundreds of branches. Genotypes within chimeric corals showed high relatedness, indicating that genetic similarity is a prerequisite for long-term acceptance of non-self genotypes within coral colonies.While some brooding corals have been shown to form genetic chimeras in their early life history stages under experimental conditions, this study provides the first genetic evidence of the occurrence of coral chimeras in the wild and of chimerism in a broadcast spawning species. We hypothesize that chimerism is more widespread in corals than previously thought, and suggest that this has important implications for their resilience, potentially enhancing their capacity to compete for space and respond to stressors such as pathogen infection