• Abundance and Population Structure of the Blacklip Pearl Oyster, Pinctada margaritifera l. 1758 (Bivalvia: Pteriidae), in Coastal Kenya

      Kimani, E.N.; Mavuti, K.M. (Western Indian Ocean Marine Science Association (WIOMSA), 2002)
      Pearl oysters are an important marine resource within the Indo-Pacific oceans. They are widely cultured for the production of black pearls, their flesh is eaten, and their shell, known as mother-of-pearl (MOP) is used in the ornament and button industry. The blacklip pearl oyster, Pinctada argaritifera L., has been harvested from East Africa for MOP for decades. A survey within nearshore habitats in Kenya showed that Pinctada margaritifera is widely distributed in shallow lagoons, bays and channels. Other oyster species found during the survey were the wing oyster, Pteria penguin, occurring in deep channels in Shimoni and Mombasa, and Pt. chinensis, within lagoons and channels in Malindi, Mombasa and Shimoni. Pinctada margaritifera was most abundant in Gazi Bay within sheltered back reefs and lagoon, and on an intertidal reef flat and back reef in Shimoni. Mean abundance and sizes declined with depth. The abundance of Pi. margaritifera in Kenya was higher than reported in the Pacific Islands and similar to abundances reported in India. The overall mean (34 mm) and maximum (154 mm) sizes were lower than those reported in the Pacific Ocean, but similar to sizes in India and the Red Sea. The oysters matured before reaching 40 mm (dorsal-ventral length), principally as males. Male sex expression was dominant, and more so in samples from moorings and jetty fouling where density was exceptionally high. The high population densities, high temperature variation and high suspended matter of relatively poor quality in the nearshore shallow lagoon environment may explain the observed life history pattern observed in the oyster populations. This study is the first comprehensive report on pearl oyster populations in Kenya.
    • Additional Information on mangrove distribution in Kenya: some observations and remark.

      Ruwa, R K; Polk, P. (1986)
      The distribution of mangroves in the tropics is linked with the presence of estuaries and creeks. There is a consensus that river discharges into the oceans cause the brackish water micro-environment; which is the key factor for development of mangroves and that in sheltered conditions they form luxuriant forests. In Kenya a similar pattern exists, but with some specific differences. For example there no mangrove trees in the estuary of River Sabaki despite the fact that it is a permanent river. In addition, the bulk of the mangrove forest cover occurs in creeks and estuaries of seasonal rivers. There also mangrove trees growing at places without any river inputs, such as: in front of rocky cliffs where there is heavy wave action; in the sheltered inlets of the sea whose ambient water salinities are oceanic i.e. 35%; in a sheltered site behind the high rocky cliffs at Bamburi where some mangroves are thriving successfully. These niches occupied by some of the mangroves in Kenya appear to be exceptional at first sight. As these exceptions are most interesting we set forth to study the microenvironment of the lone mangrove of Kanamai; the estuarine system at Gazi mangrove swamp; the Mida creek mangrove ecosystem with an aim of explaining the distribution patterns of the mangroves in Kenya.
    • Algal Turf Dominates Mombasa Marine Park and Reserve in Kenya, an Implication of Nutrient Pollution.

      Munga, C.N.; Vanreusel, A.; Obura, D.; Dahdouh-Guebas, F.; Mohamed, M.O.; Amiyo, N. (Vlaams Instituut voor de Zee (VLIZ)Oostende, Belgium, 2008)
      Mombasa Marine Park and Reserve is one of the Marine Protected Areas in Kenya established more than ten years ago. The Park is a no-take-zone, while the Reserve is a zone where regulated extractive uses such as artisanal fishing are allowed. Since the year 2004, ecological monitoring of the MPA has been going on aimed at generating information on the MPA status with a view to improve its management. Four year monitoring data (2004 to 2007) of percentage benthic cover using the Line Intercept Transect (LIT) method reveal relatively high average percentage benthic cover for algal turf in both the Park and Reserve with sampling sites and seasons. If not checked, algal turf could easily out compete and degrade the hard corals and sea grass beds that are important for MPA ecological and biological health status. The growth of algal turf is triggered by nutrient input mainly from land sources. It is therefore important to identify the nutrient input sources into the MPA so as to address management measures to remedy this ecological threat.
    • An alternative management strategy for Lake Victoria (Kenya)..

      Lwenya, C.; Abila, R.; Ouko, J.; Onyango, J.; Bwana, E.; Wanjiru, R. (Lake Victoria Fisheries Research ProjectJinja, Uganda, 2000)
      In Kenya, fisheries resource management has been based on the top-down centralized approach since the colonial days. Stakeholders have never been consulted concerning management decisions. The 4-beaches Study was undertaken to investigate the potential for an alternative management system for Lake Victoria.
    • Aquaculture Training for Kenyan Fisheries Officers and University Students - Ninth Work Plan, Adoption/Diffusion Research 3 (9ADR3) Progress Report.

      Veverica, K.; Ngugi, C.; Amadiva, J.; Muchiri, M.; Bowman, J. (Oregon State UniversityCorvallis, Oregon, 2002)
      Lack of technical training has been cited as a major reason for the low output of fish ponds in Kenya. The lack was observed at all levels, from the lowest-level extension agent through university levels. The training program undertaken by the Kenya Project in Kenya seeks to improve training and to provide a cadre of trainers who have extensive practical fish-production experience. This year the Kenya Project continued scholarship support for two M.S. students, one at Moi University’s Chepkoilel Campus, Eldoret, Kenya, and the other at Auburn University, Alabama. Small stipends for student research conducted at Sagana Fish Farm have allowed undergraduate as well as graduate-level university students to remain longer to complete projects and gain valuable field experience. The series of short courses for personnel of the Kenya Fisheries Department (FD), begun in 1999 and 2000, was concluded this year with the fifth and final course planned under this activity. In this series of courses, more than 80 FD staff received two weeks of training in pond construction methods and pond management techniques, and an additional 26 persons (24 Fisheries Officers and 2 outside-funded participants) received three weeks of advanced training in pond construction, pond management, and business planning. Additional farmer field days for approximately 50 farmers are also planned for later in 2001.
    • Aquatic biodiversity of Lake Victoria basin

      Wakwabi, E.O.; Balirwa, J.; Ntiba, M.J.; Odada, E.O.; Olago, D.O.; Ochola, W.O. (United Nations Environment Programme (UNEP), Pan African START Secretariat (PASS)Nairobi, Kenya, 2006)
      Lake Victoria is the largest lake in Africa, with the largest freshwater fishery in the world. There are nine main affluent river basins (Sio, Nzoia, Yala, Nyando, Sondu-Miriu, Awach, Kuja, Mara, and Kagera), and one surface outlet, the River Nile. The basin has extensive wetlands and small water bodies, which have (or had) a hydrological connection with Lake Victoria and therefore constitute potential “refugia” for biotic and genetic diversity from the main lake. The biological diversity in these waters is known to be exceptional both in number of species and in their endemism. While the ecosystem changes have been documented, causes of these changes remain uncertain due to lack of basic data on the abundance and diversity of the biota. Through the Lake Victoria Environmental Management Project (LVEMP), the three riparian states of Kenya, Uganda and Tanzania, with assistance from the Global Environmental Facility (GEF) and the International Development Agency (IDA) have collectively responded to the issues of ecosystem and resources degradation in the lake basin. Areas of concern which constituted specific components of the project were declining fisheries, proliferation of the water hyacinth, extreme sediment and pollution loads in the river and lake waters, reduced vegetation and forest cover in the catchment, wanton clearance and draining of wetlands and poor land use practices in and around the basin. One of the critical components of LVEMP therefore concerned Fish Biology and the Conservation of Aquatic Biodiversity. This document provides information on the pertaining situation of the basic biodiversity in the Lake Victoria basin. The composition, diversity, distribution as well as the ecological and socio-economic importance of the various species have been presented. The communities discussed include macroinverterbrates, phytoplankton, macrophytes, invertebrates, and vertebrate. The need for more studies to ensure sustainability as a result of the ongoing exploitation is emphasised.
    • Assessing Coral Community Recovery from Coral Bleaching by Recruitment in Two Reserves in Kenya.

      Visram, S.; Mwaura, J.; Obura, D.O. (2008)
      In 2003 and 2005, studies were carried out on the density of small coral colonies (<10 cm) on three reefs in the Mombasa Marine National Park and Reserve on the southern fringing reef system of Kenya, and on three reefs in the Kiunga Marine National Reserve in the north of the country. All the study sites were impacted by a major coral bleaching event in 1998. A total of 28 coral genera from 12 families were recorded, of which 17 genera were recorded on both northern and southern sites. Two or three genera of corals contributed 50-60% of all small colonies in both regions, with Porites, Coscinarea and Pocillopora the main contributors of small colonies in Kiunga, and Pocillopora being the most abundant genus of small corals in Mombasa in both years. The densities of small colonies were lowest at the northern sites, and small colonies of genera of corals that suffered from high bleaching and mortality during the El Niño Southern Oscillation in 1998 were less abundant in the north. These northern reefs are relatively isolated from sources of coral larvae from reefs in the south, and are seasonally influenced by nutrient-rich, cooler water due to the influence of the Somali Current and the northeast monsoon winds. The data presented here support our preliminary assessment that these northern reefs are less likely to recover by natural recruitment. These reefs are therefore more vulnerable to environmental perturbation such as the conditions that elicited coral bleaching on the study reefs in 1998.
    • An Assessment of Kenya's Coastal Tourism.

      Achieng, O.; Okidi, C.O.; Westley, S. (University of Nairobi, Institute for Development StudiesNairobi, Kenya, 1978)
      Kenya's fundamental policy is to maximise net economic benefits from tourism, subject to social, cultural, environmental and political constraints. In practice this means maximising wealth generated by tourism (with raising net foreign exchange receipts as one component), increasing employment opportunities, increasing Kenyan ownership and management of a growing industry, and reducing any undesirable social or environmental consequences of tourist expansion. In this particular respect, tourism at the Coast plays a particularly important role in the overall development of tourism as vital sector of the national economy.
    • The autecology of the edible oyster Crassostrea cucullata Born, 1778: size related vertical distribution at Mkomani, Mombasa

      Ruwa, R.K.; Okemwa, E.; Polk, P. (The Kenya National Academy of Sciences, 1986)
      The littoral oyster Crassostrea cucullata occurs between 1.05-3.35 m above chart datum with the highest density occuring between 1.85-2.75m. Its distribution is size-related as demonstrated by computation of correlation coefficients (r) and regression equations. The shell lengths (i.e. maximum linear dimension) decreases in an upshore direction. The analysis show high r-values which are significant at P<0.001. The elevation and density related effects on the shell lengths of the oysters are discussed.
    • Background information on Nyando Wetland.

      Raburu, P. O.; Khisa, P.; Masese, F.O.; Raburu, P.O.; Okeyo-Owuor, J.B.; Kwena, F. (Kenya Disastern Concern - VIRED - UNDPNairobi, Kenya, 2012)
      This chapter addresses the geological, geomorphological, climatic and hydrological conditions prevailing in the Nyando Wetland and the surrounding area. Nyando Wetland is part of the many papyrus dominated wetlands in the Lake Victoria Basin. The wetland is located at the mouth of Nyando River but it is contiguous with other lakeshore wetlands forming the second largest wetland (14,400ha) on the Kenyan side of the Lake Victoria Basin. Within it are a number of small wetlands whose major sources of water include direct precipitation, runoff from upland areas, inflow from rivers, recharge from aquifers and backflow from the lake during flooding. The wetland is incised within the Kano Plains, which is a floodplain riparian zone transitional between the surrounding upland areas on one end and the Lake Victoria at the other extreme end. Land-use activities in the upper Nyando River Basin have a strong bearing on the Nyando Wetland through their influences on water quantity and water quality. Because of deforestation activities in the upper basin, water quality has been deteriorating and quantity fluctuating in the river, with increased peak flows during the rains resulting in widespread flooding in the lowlands. During the dry season, base flows in the rivers and streams are considerably reduced, resulting in the drying up of large sections of the wetlands. The wetlands are rich with diverse plants and animal life. The common species of macrophytes, macroinvertebrate, amphibians, reptiles, fish, birds found in the wetlands are also presented together with their conservation status. The Nyando Wetland has undergone changes as a result of climatic and human-induced perturbations within the wetlands themselves and in the catchment of rivers draining into or through the wetlands. These activities continue to compromise the ecological integrity of this fragile ecosystem. The sustainable conservation and management of the wetlands would benefit greatly from concerted efforts by all stakeholders.
    • Beach Sand Supply and Transport at Kunduchi in Tanzania and Bamburi in Kenya.

      Shaghude, Y.W.; Mburu, J.W.; Uku, J.; Ochiewo, J.; Nyandwi, N.; Onganda, H.; Magori, C.; Sanga, I.; Arthurton, R.S. (2012)
      Beach-head erosion of sandy beach plains in eastern Africa threatens tourism-related infrastructure and the livelihoods of beach users. The nature and drivers of physical shoreline change at Kunduchi, Dar es Salaam, and Bamburi, Mombasa, are described with analyses of beach sand transport through the annual monsoon cycle and the provenance and sustainability of the beach sand supply. Time-series records of wind-vectors at Dar es Salaam and Mombasa show similar averaged patterns. Because of the contrasting alignments of these coasts, the net wind-wave driven longshore transport at Kunduchi (trending NNW) is northnorth-westwards, while at Bamburi (trending NNE) there is little net transport. At Bamburi, the beaches are recharged with reef/platform-derived calcium carbonate sand and siliciclastic sand discharged from the hinterland via tidal channels. At Kunduchi, recharge comprises mostly river-borne siliciclastic sand, but riverine sand mining threatens natural replenishment, jeopardising beach maintenance. Eroding beach plain deposits contribute siliciclastic sand at both sites.
    • Biomass accumulation in a rehabilitated mangrove forest at Gazi Bay

      Tamooh, F.; Kairo, J.; Huxham, M.; Kirui, B.; Mencuccini, M.; Karachi, M. (African Studies CentreLeiden, Netherlands, 2009)
      Estimation of biomass in woody ecosystems is important because of its role in wood yield determination, relevance to nutrient turnover, and the potential to store carbon. Most studies on mangrove biomass have over the years tended to concentrate on standing biomass with very little on below-ground biomass. The present study estimates total above and below ground biomass in mangroves. Allometric relations were developed relating biomass with easily measurable parameters in a young six-years Rhizophora mucronata plantation established in 2001 in an originally El Nino impacted site at Gazi Bay. Twelve isolated trees were sampled using destructive method. The stem diameters were measured at first branching (DB) and diameter at 30 cm from the highest prop root (D sub(30)). Total above-ground biomass gave the best fit (r2=0.97) when regressed against the independent variable D302H. There was a clear correlation between below-ground biomass (BGB) and D30(30) 2H (r2=0.98). The best estimator for total biomass gave the best fit when regressed against D302H (r2=0.98) using the equation B total (g dry weight) =2.0095 x D302H (cm2) + 1463.1. Overall, above-ground biomass and below ground biomass accounted for 63-82% and 18-37% of the total dry weight respectively. Allometric equations developed in this study provide a useful tool of estimating total biomass in replanted mangroves and hence improve on forest management.
    • The Body Composition of Low Value Fish and their Preparation into a Higher Value Snack Food.

      Oduor-Odote, P.M.; Kazungu, J.M. (2008)
      —In Kenya, marine catfish (Galeichthys feliceps) and ribbonfish (Trichurus lepturus) are both under- utilized species from the prawn fishery where they occur as by-catch or discards. They represent a potentially valuable source of protein mince. The current study assessed the feasibility of increasing the value of this by-catch by testing its suitability to the production of snack foods which was prepared with locally available flour from rice, wheat and maize. The ratio of fish mince to flour, the carbohydrate component, was tested in the snack foods at rations of 2.5:1; 2:1 and 1:1. An untrained taste panel using a hedonic scale of 1 to 9 tested preference. Protein content, fat, moisture, amino acid and fatty acid composition are reported and both indicate the nutritional suitability of the selected fish. The overall order for preference was ribbonfish with rice then ribbonfish with wheat, catfish with rice, ribbonfish with maize and catfish with wheat. Rice was preferred for value addition and ribbonfish was the preferred fish in the formulations.
    • The breeding pattern and variations in timing and reproductive output of the commercial sea cucumber Holothuria fuscogilva in Kenya.

      Muthiga, N.A.; Kawaka, J.A. (2009)
      The sea cucumber Holothuria fuscogilva is currently one of the most commercially valuable species of sea cucumber worldwide. This study investigated reproduction of this species in order to characterize the reproductive pattern and evaluate the relationship with temperature, light and lunar periodicity. Individuals were collected monthly, between 1998 and 2007, at Shimoni, Kenya and processed using standard gonad index methods and macroscopic and microscopic observations of the gonads. Gametogenesis commenced from May and spawning occurred from December to April of each year and there was close synchrony between the sexes, contrary to the hypothesis that breeding patterns on the equator will be continuous and less synchronized between sexes. Peak spawning occurred during the last quarter of the moon. The gonad index of individuals correlated significantly with gonad tubule length and fecundity indicating that it was a good predictor of sexual maturity and reproductive output. The gonad index showed a significant correlation with temperature but not light, suggesting that temperature may play a role in controlling reproduction. The life history strategy of this sea cucumber included a higher energetic investment in the reproductive output of females and spawning at a time favorable for larval development. There was a shift in sex ratio from unity to significantly more males over the sampling period, as well as a significant reduction in mean sizes (body wall weight) and reproductive output (gonad index) suggesting that the reproductive success of this species was potentially negatively affected by fishing.
    • Breeding Studies on Tilapia Zillii and Tilapia Nigra.

      Cridland, C. (East African Freshwater Fishery Research OrganizationJinjga, Uganda, 1961)
      Broods were recorded from seven pairs of T. zilli which had been reared from previous experiments in the laboratory, observations on these being made for a period of 19 months.
    • Buoy Release Trials.

      Roberts, J. (East African Freshwater Fishery Research OrganizationJinja, Uganda, 1961)
      Trials with the two types of links supplied by E.A.Industrial Research Organization and using sealed one gallon cans as floats produced results as follows.
    • Capacity building for Lake Victoria water quality monitoring and assessment in Kenya.

      Okungu, J.; Abuodha, J.O.Z.; Hecky, R.E.; Abuodha, J.O.Z.; Hecky, R.E. (Lake Victoria Environment Management Project (LVEMP)Kisumu, Kenya, 2005)
      Training programs were designed to provide scientists with strengths in applied limnology, monitoring and the environment. In addition, the training provided scientists with a firm background in data analysis, interpretation and synthesis procedures, including statistics, numerical analysis, programming and conceptual modelling methods. Most hydrologists and water chemists in public and private employment were educated in a tradition that emphasized qualitative schooling, and this project therefore has managed to train a new type of scientist who can apply calculations to their research, monitoring or operational undertakings. The scientists also benefited from adequate training in computer analytical techniques, most notable in the area of model applications, graphics; including map, contour plotting, remote sensing interpretation, GIS; and interpretation of water quality data. The scientist obtained both practical and theoretical knowledge, thus are now able to integrate and apply a number of scientific disciplines to problems of relating to the water quality monitoring of the lake and its ecosystem, in addition to environmental management and conservation of the catchment. By participating in high level courses in addition to computer training and fieldwork, the scientists have now acquired an in-depth understanding of the fundamental principles of limnology and water quality monitoring. The scientists of this programme are now well-grounded field specialists, who apart from their high specialization in water related issues appreciate the exigencies of other related disciplines. Their specializations within an interdisciplinary/transdisciplinary framework have resulted in versatile international scholars armed with knowledge, awareness and skills to assess and solve pertinent environmental issues and problems afflicting the lake. Apart from training, some infrastructure for water quality monitoring has been established in the lake basin. In Kisumu, laboratories based at the Ministry of Water and Irrigation at Nyalenda was rehabilited and equipped with more sophisticated equipment. However, there is need to build and equip more laboratories in the lake region to lessen transportation and enable quicker analysis of samples. There is now a basin-wide network for data collection in the inshore and offshore areas in addition to establishment of a meteorological network. Monitoring programs have involved placement and utilization of the harmonized monitoring network. Quality control and quality assurance mechanisms is now practiced and coordinated by the component. LVEMP has put emphasis on establishment of internal and regional quality assurance mechanisms, enhancement of laboratory performances and efficiency, and data generation and management. Although research vessels were obtained from the Kenya Marine and Fisheries Research Institute, this arrangement was not efficient since the vessels were obtained only at the discretion and convenience of the latter; it would probably be better if the component could acquire its own vessel to guarantee effective implementation of logistics.
    • Capacity Building: Training, Infrastructure, Equipment and Monitoring Programmes for Conservation of Lake Victoria.

      Okungu, J.O.; Rutagemwa, D.K.; Ssenfuma-Nsubuga, M.; Abuodha, J.O.Z.; Mwanuzi, F.L.; Muyodi, F.J.; Hecky, R.E. (Lake Victoria Environmental Management Project (LVEMP)Kisumu Kenya, 2005)
      Training programs were designed to provide scientists with strengths in applied limnology, monitoring and the environment. In addition, the training provided scientists with a firm background in data analysis, interpretation and synthesis procedures, including statistics, numerical analysis, programming and conceptual modelling methods. Most hydrologists and water chemists in public and private employment were educated in a tradition that emphasized qualitative schooling, and this project therefore has managed to train a new type of scientist who can apply quantitative methods to their research, monitoring or operational undertakings. The scientists also benefited from adequate training in computer analytical techniques, most notable in the area of model applications, graphics; including mapping, contour plotting, remote sensing interpretation, GIS; and interpretation of water quality data. The scientists obtained both practical and theoretical knowledge, thus they are now able to integrate and apply a number of scientific disciplines to problems of relating to the water quality monitoring of the lake and its ecosystem, in addition to environmental management and conservation of the catchment. By participating in high level courses in addition to computer training and fieldwork, the scientists have now acquired an in-depth understanding of the fundamental principles of limnology and water quality monitoring. The scientists of this programme are now well-grounded field specialists, who apart from their high specialization in water related issues appreciate the exigencies of other related disciplines. Their specializations within an interdisciplinary/ trans-disciplinary framework have resulted in versatile international scholars prepared with knowledge, awareness and skills to assess and solve pertinent environmental issues and problems afflicting the lake. Apart from training, elaborate infrastructure for water quality monitoring has been established in the region. In Kisumu, Mwanza, Bukoba and Musoma laboratories were rehabilitated and equipped, whereas the Entebbe laboratory was equipped with more sophisticated equipment. There is now a regional network for data collection in the inshore and offshore areas in addition to establishment of a precipitation network. Monitoring programs have involved placement and utilization of the harmonized monitoring network. Quality control and quality assurance mechanisms are now practiced and coordinated among the three countries. LVEMP has put emphasis on establishment of internal and regional quality assurance mechanisms, enhancement of laboratory performances and efficiency, and data generation and management. Although research vessels were obtained from each country’s fisheries research institute, this arrangement was not efficient since the vessels were obtained only at their discretion and convenience. It is recommended that this component acquire its own vessel dedicated to water quality research to guarantee effective implementation of the monitoring program in the future.
    • The capacity of fisherfolk to implement beach management units in Diani-Chale.

      Oluoch, S.; Obura, D.; Hussein, A.; Hoorweg, Jan; Muthiga, N. (African Studies CentreLeiden, Netherlands, 2009)
      The main objective for the formation of fisher groups in Diani-Chale was the initiation of development projects to improve their living standard and achieve self-reliance. Advocacy for fisher rights, equipment/gear purchase and fishers welfare were mentioned as additional objectives (in order of importance). Revenue collection and conflict resolution were stated as objectives by a few members, but not by officials. Conversely, conservation/sanitation and marketing of fish was an important objective for group officials but not for the membership.
    • Causes of biodiversity loss in coastal ecosystems.

      Martens, E.E.; Bennun, L.A.; Aman, R.A.; Crafter, S.A. (Centre for Biodiversity, National Museums of KenyaNairobi, Kenya, 1995)
      Although far less published than loss of biodiversity on land, the loss of marine genetic, species and ecosystem diversity is a global crisis in its own right. The coastal strip (the shallow water, the intertidal area and the immediately adjacent land) is the most vulnerable as well as the most abused marine zone. Coastal ecosystems are not only an important source for essential products for mankind, including foods, medicine, raw materials and recreational facilities, but also provide ecological services that directly benefit the coastal zone. Loss of biodiversity in coastal ecosystems has both direct and indirect causes. The direct mechanisms involved include habitat loss and fragmentation, physical alteration, over-exploitation, pollution, introduction of alien species and global climate change. The root causes that drive these proximate threats lie in the high rate of human population growth, the unsustainable use of natural resources, economic policies that fail to value the environment and its resources, insufficient scientific knowledge, and weak legal and institutional systems. The ever-growing exploitation of the coast and its resources is a reflection of the steady population increase, especially in coastal zones. Habitats are changed or lost by accelerating urbanization, development of tourist facilities, industrial installations and mariculture. Land-based and upstream activities alter sedimentation and freshwater input in downstream estuaries and coastal biotopes. Contaminants from sewage disposal and agricultural runoff are rapidly increasing and areas of eutrophication and chemical pollution are expanding. Careless disposal of plastic wastes not only causes a litter problem but also widespread mortality of marine species. Exploitation of living marine resources may damage habitats and alter food webs, while mariculture generates its own pollution and may upset ecological balances by the introduction of alien species. Global atmospheric changes, which may result in altered rainfall patterns and rising sea-level, have become a matter of growing human activities have dramatically increased the intensity, pace and kind of environmental changes that lead to habitat loss and pose severe adaptive challenges to marine organisms. Response to these changes includes drastic declines of many fisheries and extinction of several species. The loss of species and ecosystems obscures the important threats to genetic diversity, which is essential for species survival in a changing environment.