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  Subjects -> WATER RESOURCES (Total: 160 journals)
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Western Indian Ocean Journal of Marine Science
Number of Followers: 1  

  This is an Open Access Journal Open Access journal
ISSN (Print) 0856-860X
Published by African Journals Online Homepage  [261 journals]
  • Abundance, spatial distribution and threats to Indo-Pacific bottlenose
           dolphins (Tursiops aduncus) in an Important Marine Mammal Area in Tanzania

    • Authors: Magreth P. Kasuga, Modest D. Varisanga, Tim R.B. Davenport, Narriman Jiddawi, Gill T. Braulik
      Pages: 1 - 14
      Abstract: Abundance estimates of cetaceans in the western Indian Ocean are rare, but important, as many cetacean populations are under threat, especially those in coastal habitats.  This study aimed to generate first estimates of abundance for Indo-Pacific bottlenose dolphins (Tursiops aduncus), assessed as Near Threatened on the IUCN Red List, in an area identified by the Marine Mammal Protected Area Task Force as an ‘Important Marine Mammal Area’.  Two study sites were surveyed along the east and west coastlines of the Pemba Channel, Tanzania.  In west Pemba, between 2014 and 2016 four boat-based visual surveys conducted a total of 2467 km of survey effort sighting a total of 16 groups of T. aduncus. Abundance was estimated using mark-recapture models of photo-identified individuals as 83 animals (CV 7.8%, 95% CI 72-97) in the 1084km2 study area.  In the Tanga study area in 2016 two boat-based visual surveys covered 1254 km of effort during which 15 groups of T. aduncus were sighted, resulting in a photo-ID based mark-recapture abundance estimate of 196 (CV 8.9%, 95% CI 165-233) individuals in the 1562 km2 study site. Group encounter rate for this species in Tanga was double that recorded in the Pemba study site. A total of 23% of identified dolphins bore the scars of interactions with fishing gear.
      PubDate: 2022-08-23
      DOI: 10.4314/wiojms.v21i1.
      Issue No: Vol. 21, No. 1 (2022)
  • Use of physicochemical parameters and metal concentrations in assessing
           anthropogenic influences on coastal rivers in Dar es Salaam, Tanzania

    • Authors: Zakaria Mhande, Matobola J. Mihale, Harieth Hellar-Kihampa
      Pages: 15 - 33
      Abstract: Spatio-temporal variations in water quality of three rivers along the Indian Ocean coast in Dar es Salaam, Tanzania, were investigated based on physicochemical parameters and metal concentrations. A compliance analysis was performed based on the Tanzania Bureau of Standards (TBS) and World Health Organization (WHO) limits to examine the suitability of water for domestic use. The dataset was subjected to statistical analysis to determine differences and similarities amongst the rivers. Levels of pH (6.83-11.41), total dissolved solids (203–34,333 mg/L), electrical conductivity (9,408-68,014 μS/cm), turbidity (10.0-45.0 NTU), chloride (108-14,248 mg/L), sulphate (35-766 mg/L) and ammonium (40-5,468 μg/L) complied with neither TBS nor WHO limits. Dissolved oxygen (1.4-6.6 mg/L), chemical oxygen demand (91-1,863 mg/L), total suspended solids (11.9-50.7 mg/L), alkalinity (200-2,658 mg/L), total hardness (362-12,1312 mg/L), salinity (0.19-29.35 ppt) and phosphate (<method detection limit-3.01 μg/L) indicated polluted water in parts of the rivers. Pb (0.7-24.0 μg/L) exceeded both the TBS and WHO limits, whereas Cr, Cu, Fe, Zn and Cd were below limits. Water quality was poorer during the wet season. The results indicate that water from the rivers is unsafe for human consumption and the poor water quality probably also affects the ecology of the rivers. Strategic measures to protect the rivers from further contamination are suggested.
      PubDate: 2022-08-23
      DOI: 10.4314/wiojms.v21i1.
      Issue No: Vol. 21, No. 1 (2022)
  • Perceived benefits and barriers to community participation in development
           projects – The case of Hazina ya Maendeleo ya Pwani on the Kenya coast

    • Authors: Melckzedeck K. Osore, Farida A. Hassan, George N. Morara
      Pages: 35 - 49
      Abstract: Benefits and barriers to participating in community development projects as perceived by participants were studied in coastal counties of Kenya through a World Bank-funded initiative known as Hazina ya Maendeleo ya Pwani (HMP). Primary data were collected from 326 randomly selected HMP beneficiaries using questionnaires. Data analysis using SPSS prioritized perceived benefits of participation as: acquisition of additional financial support (94 %); development of new skill (90.8 %); enhanced ability to meet own individual needs (90.8 %); development of valuable professional relationships (90.8 %); acquisition of useful knowledge (84.2 %); increased utilization of own expertise (77.9 %) heightened public profile (77.2 %); ability to contribute to community (71.9 %); ability to have greater impact (68.8 %); and enhanced ability to effect public policy (49.1 %). Perceived barriers were prioritized as: feeling unwelcome (89.4 %); lack of information or not knowing (87.9 %); feeling unable to make a difference (87.9 %); demanding work schedule at home or office (69.7 %); inadequate transportation (50.8 %); and concern for safety (43.2 %). The study concluded that while the perceived benefits still strengthen the argument for active involvement of communities, development practitioners need to incorporate “what’s in it for me'” as an incentive for participation in future. They should also develop context-specific strategies to overcome participation barriers.
      PubDate: 2022-08-23
      DOI: 10.4314/wiojms.v21i1.
      Issue No: Vol. 21, No. 1 (2022)
  • Assessment of tropical cyclone-induced shoreline and riverbank changes at
           the Rufiji Delta using satellite remote sensing methods

    • Authors: Kombo H. Kai, Julius Francis, Yohanna W. Shaghude
      Pages: 51 - 63
      Abstract: The study aimed at quantifying changes in shoreline and riverbanks caused by tropical cyclones (TCs) and associated rainfall in the Rufiji Delta, southern Tanzania. Long term changes of the shoreline and riverbanks were analysed using medium resolution (Landsat TM and ETM) satellite imagery (1991, 1997 and 2007), while short-term changes (2013 to 2014) were analysed using high resolution (Pleiades) satellite imagery. Delineation of the shoreline and riverbank changes were accomplished through the analysis of appropriate coloured image composites, Sobel filtering and maximum likelihood classification of land cover. Analysis of Landsat data showed a relatively higher magnitude of erosion between 1991 and 2007, followed by minor changes between 1997 and 2007. Simbauranga was the most severely eroding site, with an estimated magnitude of erosion of 83 to 100 m during the study period. The maximum magnitude of short-term changes of the riverbanks were estimated at about 31 m2. Apart from the erosion of the riverbanks, other changes were the conversion of water to vegetation covered areas (amounting to approximately 200 m2). Short-term shoreline changes were up to 206 m with higher magnitude of accretion (142 m) than erosion (-4 m). The study conclusively calls for further detailed research on shoreline and riverbank changes based on the impacts of TCs on land cover.
      PubDate: 2022-08-23
      DOI: 10.4314/wiojms.v21i1.
      Issue No: Vol. 21, No. 1 (2022)
  • Additions to the marine decapod (Crustacea: Decapoda) fauna of South

    • Authors: Jannes Landschoff, Charles L. Griffiths, Lara J. Atkinson, Kerry J. Sink, Thomas P. Botha
      Pages: 65 - 76
      Abstract: This report adds five previously unreported species to the decapod crustacean fauna of South Africa, as well as removing one species previously listed in error. It also documents locality (and/or reference specimen) data for 12 other species, most of which had been depicted in regional field guides, but without reporting when and where they had been collected. Almost all the species added were already known from adjacent African countries and their ranges are here extended into South Africa. Although some of these records are based on photographs, rather than collected specimens, it is argued that such records should be accepted as adequate evidence for inclusion of at least visually-distinctive crustacean species into the regional fauna.
      PubDate: 2022-08-23
      DOI: 10.4314/wiojms.v21i1.
      Issue No: Vol. 21, No. 1 (2022)
  • Assessment of vertical and horizontal distribution of meiobenthos along a
           salinity gradient in the Tana and Sabaki Estuaries, north coast Kenya

    • Authors: Joel Amisi, Cosmas Munga, Nina Wambiji, Edward Kimani
      Pages: 77 - 89
      Abstract: Meiobenthos respond to variability in salinity gradients in estuarine habitats and are thus suitable organisms for ecological studies. The vertical and horizontal distribution of the meiofauna community structure of two major estuaries (Sabaki and Tana) on the north coast of Kenya were compared. The aim was to draw a meiofaunal dataset inventory of the two estuaries and to examine how salinity gradient, seasonality and sediment characteristics influence their structure. Replicate samples were collected from three sampling stations along the salinity gradient of each river estuary. A total of 3,556 individuals belonging to 26 taxa were recorded. Based on seasons and across stations, the upper surface (0-5 cm) layer recorded the highest meiobenthic density (90 ± 42 ind.10 cm-2), followed by 46 ± 23 ind.10 cm-2 (5-10 cm) and 30 ± 8 ind.10 cm-2 in the deepest sediment layer (10-15 cm) studied. The southeast monsoon season recorded the highest mean density (160 ± 22 ind.10 cm-2) compared to the northeast monsoon season (22 ± 12 ind.10 cm-2) for both estuaries. Results of the non-Metric Multidimensional Scaling technique revealed distinct seasonal composition in meiobenthos but not between the estuaries. Results of the 2-way ANOSIM test confirmed no significant differences in meiobenthic composition between the estuaries (p = 0.712). However, seasonal difference was significant (p = 0.001) with higher densities for nematoda (166 ± 99 ind.10 cm-2 and 56 ± 29 ind.10 cm-2) recorded in Tana and Sabaki, respectively during the southeast monsoon season. At least 7 taxa out of a total of 26 were present in both estuaries. Salinity gradient, season and sediment depth were found to influence the meiobenthic densities and taxa composition.
      PubDate: 2022-08-23
      DOI: 10.4314/wiojms.v21i1.
      Issue No: Vol. 21, No. 1 (2022)
  • Patterns of fish community structure in protected and non-protected marine
           areas of mainland Tanzania

    • Authors: Fausta G. Salema, Nsajigwa E. Mbije, Eliezer B. Mwakalapa, Alfan A. Rija
      Pages: 91 - 101
      Abstract: Information on the benefits of Marine Protected Areas (MPAs) for the condition of fish stocks is not well documented in Tanzania. Fish landing sites located in Tanga and Mtwara regions were surveyed to assess patterns of fish community structure; particularly fish abundance, species diversity, growth patterns, and maturity stages, based on catches landed at sites with different protection status. Fish abundance in the catch from protected areas was significantly lower than in non-protected areas (p=0.002). Species diversity was relatively higher in catches from non-protected (H=2.742) compared to protected areas (H=2.232). A high percentage of species (63.24 %) exhibiting negative allometric growth was observed in catches from non-protected areas. Further, a large number of mature fish was observed in catches from protected areas compared to non-protected areas (p<0.01). These indices are useful indicators of the performance of MPAs. The observed negative allometric growth and reduced number of mature fishes in the non-protected areas suggest that extractive pressure and disturbances from fishing gears have negative impacts on the fish stock. Continued high extraction may induce a decline in general fish size due to the constant selection for large-trait fish specimens, potentially causing evolutionally change in morphological traits. In contrast, the lower abundance and species diversity from the protected areas reflected low catch effort as a result of regulated fishing pressure in MPAs, rather than indicating the actual diversity in the fish stocks in these protected waters. Based on these findings it is recommended that more regulatory strategies are implemented in non-protected waters to allow more time for fish to attain appropriate harvest sizes and to ensure the effective protection of marine resources.
      PubDate: 2022-08-23
      DOI: 10.4314/wiojms.v21i1.
      Issue No: Vol. 21, No. 1 (2022)
  • The influence of household human and social capitals on participation in
           agricultural development initiatives in the coastal region of Kenya

    • Authors: Annie H. Ong'ayo, Farida A. Hassan
      Pages: 103 - 112
      Abstract: The present study sought to establish the human and social capital that determines rural households’ participation in agricultural projects and programmes implemented by the Kenyan government and development partners. The research was carried out among rural households in the three counties of the coastal region of Kenya. Multi-stage sampling techniques (purposive, proportionate random and simple random sampling) were used to select the study area and the study sample. Data were collected using a semi-structured questionnaire, Focus Group Discussion and observation schedules. The data analysis was carried out using descriptive statistics and regression analysis with the help of the Statistical Package for Social Sciences Version 22. The findings revealed that individuals with human capital; namely age (-0.15), primary education (-0.16), secondary education (-0.14), vocational training (0.35), and on the of job training (0.25), have a higher likelihood of participating in agricultural development initiatives. Households with the social capital of membership to groups (0.51), engaged in economic activities (0.53) and have linkages with development agencies (0.44) have a higher likelihood of participating in development initiatives. Key policy recommendations for county government and development partners include: encourage the community members to enrol in adult education; provide support for vocational and technical training; register as members in existing groups or form groups based on common interest, and engage in economic activities. The county governments should enhance advisory services to ensure close contact with professionals who will facilitate training, meetings and interactions with groups leading to the empowerment of members.
      PubDate: 2022-08-23
      DOI: 10.4314/wiojms.v21i1.
      Issue No: Vol. 21, No. 1 (2022)
  • Phytoplankton distribution along a salinity gradient in two Kenyan
           saltworks (Tana and Kurawa)

    • Authors: Sheban M. Hinzano, Francis A. Okalo, Morine M. Ngarari, Mary A. Opiyo, Erick O. Ogello, Alexander M. Fulanda, Dan O. Odiwour, Betty Nyonje
      Pages: 113 - 124
      Abstract: The current study assessed the diversity and abundance of phytoplankton genera in two Kenyan saltworks (Tana and Kurawa) in March and September 2021. Water samples were obtained from ponds with salinities ranging from 30 to 200 ppt by filtering 40 l of water using a 20-μm phytoplankton net. Seventy-six genera of phytoplankton were identified. Genera richness, evenness and diversity decreased with increasing salinity while phytoplankton abundance increased with increasing salinity. Higher phytoplankton densities were observed in the Tana than in the Kurawa saltworks. Ponds of <100 ppt were dominated by Dinophyceae and Bacillariophyceae which accounted for >90 % of the phytoplankton community. Ponds of salinities >100 ppt were dominated by Cyanophyceae which accounted for >90 % of the phytoplankton community. From the results it was concluded that Kenyan saltworks host diverse phytoplankton genera whose richness decreases with increasing salinity and varies with seasons. The present data describes variation of phytoplankton assemblages in salt ponds between two selected seasons, but several samplings throughout the year would be more appropriate to describe variations of phytoplankton with season in these salt ponds.
      PubDate: 2022-08-23
      DOI: 10.4314/wiojms.v21i1.
      Issue No: Vol. 21, No. 1 (2022)
  • Review of fisheries and management of sea cucumbers in the Indian Ocean

    • Authors: Chantal Conand, Michel Claereboudt, Chamari Dissayanake, Ameer Ebrahim, Stella Fernando, Rodney Godvinden, Thierry Lavitra, Marc Léopold, Twalibu K. Mmbaga, Thierry Mulochau, Shafiya Naaem, Stanley Shea, Devarajen Vaitilingon, Saleh Yahya, Kim Friedman
      Pages: 125 - 148
      Abstract: Several sea cucumber species (Echinodermata: Holothuroidea) are fished, mostly for export of the dried product for Oriental consumers. Previous studies had analysed the historical trends at the world-scale until 2014. In the Western Indian Ocean (WIO) holothurian fisheries have a long history and several programmes have tried to ameliorate their management. Information has been recently gathered through a questionnaire and access to the most recent, yet unpublished available data (2015 to 2021) from different countries, through the evaluation of catches and/or processed product, present management systems, the imports of beche de mer and other products from Indian Ocean (IO) countries into the major market hub of Hong Kong SAR, and the Food and Agricuture Organisation (FAO) yearly statistics. The results are first presented for WIO countries, highlighting recent improvements in management. Imports from 16 WIO countries into the Hong Kong market (2017-2020 data) indicate the importance of the hub. The FAO world statistics are used to present the changes for the last few years, concentrating on the WIO countries. The recent trends show that demand for holothurians is still very high. Inconsistencies in the unit used in the reported statistics (fresh or dry weight) exist, and this needs to be addressed. The national data should be collected at the species level, to be able to follow the changes and the stock status. A regional approach is needed to encourage use of comparable management tools and follow future trends.
      PubDate: 2022-08-23
      DOI: 10.4314/wiojms.v21i1.
      Issue No: Vol. 21, No. 1 (2022)
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