Western Indian Ocean journal of marine science最新文献_第10页

Microplastic pollution in the surface waters of creeks along the Kenyan coast, Western Indian Ocean (WIO) 西印度洋肯尼亚沿岸小溪表层的微塑料污染(WIO)

Western Indian Ocean journal of marine science Pub Date : 2021-04-02 DOI: 10.4314/WIOJMS.V19I2.6

Joyce O. Kerubo, A. Muthumbi, J. Onyari, E. Kimani, D. Robertson-Andersson

{"title":"Microplastic pollution in the surface waters of creeks along the Kenyan coast, Western Indian Ocean (WIO)","authors":"Joyce O. Kerubo, A. Muthumbi, J. Onyari, E. Kimani, D. Robertson-Andersson","doi":"10.4314/WIOJMS.V19I2.6","DOIUrl":"https://doi.org/10.4314/WIOJMS.V19I2.6","url":null,"abstract":"Microplastic pollution has been recognized as a global threat in marine environments and a danger to prey, predators and humans. Yet there have been limited studies in the Western Indian Ocean (WIO) and along the Kenyan coast making it difficult to estimate the extent of such pollution. This is the first study on microplastics (MPs) in the surface waters within creeks (Tudor, Port-Reitz and Mida creeks) in Kenya. Sampling was done in January/ February and September 2018 to collect microplastics from surface water. Neuston nets of 500 μm (large) and 250 μm (medium) size were towed for ten minutes and 50 litres of seawater sieved through a 20 μm net (small) in three replicates. The samples were digested in 10 % Potassium Hydroxide, sieved, and then filtered with cellulose nitrate membrane microfilters. Concentrations of total microplastics, different shapes and colours were established under a microscope. High concentrations of small size (20-250 μm) MPs were encountered and Tudor and Port Reitz had higher concentrations compared to Mida Creek. The study provides data on microplastic concentrations within the creeks and recommends focussing on small size microplastics for monitoring purposes, which due to their high concentrations can be hazardous to organisms.","PeriodicalId":200681,"journal":{"name":"Western Indian Ocean journal of marine science","volume":"37 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128583279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 23

Fine-scale habitat use by humpback whales (Megaptera novaeangliae) in Zavora Bay, Mozambique 莫桑比克Zavora湾座头鲸(Megaptera novaeangliae)精细尺度栖息地的使用

Western Indian Ocean journal of marine science Pub Date : 2021-04-02 DOI: 10.4314/WIOJMS.V19I2.10

Charlotte D. Van Driessche, N. Cullain, Yara Tibiriçá, I. O’Connor

{"title":"Fine-scale habitat use by humpback whales (Megaptera novaeangliae) in Zavora Bay, Mozambique","authors":"Charlotte D. Van Driessche, N. Cullain, Yara Tibiriçá, I. O’Connor","doi":"10.4314/WIOJMS.V19I2.10","DOIUrl":"https://doi.org/10.4314/WIOJMS.V19I2.10","url":null,"abstract":"Little is known about the humpback whales (Megaptera novaeangliae) of the East-African Coast genetic sub-unit (C1). With an estimated population size of 7000 whales, they demonstrate the resilience of the species after commercial whaling caused population numbers to decline drastically. Zavora Bay, Mozambique offers an ideal observation point of the passage of the whales during their annual migration towards the breeding ground of southern Africa and serves as an operating base to monitor this population. This study aimed at identifying the importance of Zavora Bay as part of this breeding ground and the core regions for humpback whale use within the study area. Results showed the waters off the coast of Zavora are actively used for breeding and do not merely serve as passage towards the wintering habitats. A mother-calf pair separation with a preference for shallower waters closer to shore was observed. Besides depth and distance to shore, slope also proved to have a significant influence on the distribution of adult humpback whales. Increased survey effort and more detailed investigation of the threats to humpback whales within the waters of Zavora are recommended.","PeriodicalId":200681,"journal":{"name":"Western Indian Ocean journal of marine science","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125871427","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Morphological and meristic characters of six rabbitfish species (Family: Siganidae) in Kenya 肯尼亚6种兔鱼的形态和分生特征

Western Indian Ocean journal of marine science Pub Date : 2021-04-02 DOI: 10.4314/WIOJMS.V19I2.7

R. Anam, Chrisestom M. Mwatete, N. Wambiji

引用次数: 2

New strandings of True’s beaked whale, Mesoplodon mirus, in Mozambique and their destiny as marine bushmeat True的喙鲸，Mesoplodon mirus，在莫桑比克的新搁浅和它们作为海洋丛林肉的命运

Western Indian Ocean journal of marine science Pub Date : 2021-04-02 DOI: 10.4314/WIOJMS.V19I2.12

K. Reeve-Arnold, Jennifer Keeping, V. Cockcroft, Almeida Guissamulo

引用次数: 3

Valuation of harvested goods in Mida Creek with application of the TESSA approach 应用TESSA方法对Mida Creek收获的货物进行估价

Western Indian Ocean journal of marine science Pub Date : 2021-04-02 DOI: 10.4314/WIOJMS.V19I2.8

C. Olima, P. Muoria, M. Owuor

{"title":"Valuation of harvested goods in Mida Creek with application of the TESSA approach","authors":"C. Olima, P. Muoria, M. Owuor","doi":"10.4314/WIOJMS.V19I2.8","DOIUrl":"https://doi.org/10.4314/WIOJMS.V19I2.8","url":null,"abstract":"Mangroves are considered a highly productive blue forests resource providing services that are important to the community both locally and globally. In recent times there has been an increase in studies on valuation of ecosystem services provided by mangroves. However, there is need to provide a simplified approach to identify, assess and quantify ecosystem services. In this study the Toolkit for Ecosystem Services Site-based Assessment (TESSA) was used to assess the value of harvested goods provided by the mangroves of Mida Creek in the current state and under plausible alternative scenarios. Spatial methods (GIS) were used to collect data for the period 1985-2019, and household interviews were used to collect data on harvested goods. Descriptive statistics were used to summarize quantitative data. Results show that the estimated current annual value of harvested goods in Mida Creek is US$ 11.2 million. This value increased to US$ 14.3 million under the conservation scenario and reduced to US$ 10.9 million under the business as usual scenario (BAU). These findings add to the growing literature on ecosystem service valuation and the need to use site-specific non-modelling tools like TESSA.","PeriodicalId":200681,"journal":{"name":"Western Indian Ocean journal of marine science","volume":"77 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-04-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122037072","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

A comparative study of ocean surface interannual variability in Northern Tanzania and the Northern Kenya Bank 坦桑尼亚北部和肯尼亚北部海岸海洋表面年际变化的比较研究

Western Indian Ocean journal of marine science Pub Date : 2021-02-11 DOI: 10.4314/WIOJMS.SI2020.1.1

M. Manyilizu, P. Sagero, I. Halo, S. Mahongo

{"title":"A comparative study of ocean surface interannual variability in Northern Tanzania and the Northern Kenya Bank","authors":"M. Manyilizu, P. Sagero, I. Halo, S. Mahongo","doi":"10.4314/WIOJMS.SI2020.1.1","DOIUrl":"https://doi.org/10.4314/WIOJMS.SI2020.1.1","url":null,"abstract":"The livelihoods of most residents of Tanga (Northern Tanzania) and Malindi (Northern Kenya), rely strongly on fishing activities in the East African shelf region. Thus, understanding variations in sea surface temperature (SST) and its related parameters such as thermocline depths and upper ocean circulation are crucial. This study applies a regional model to understand interannual spatial relationships between ocean circulation and SST off Northern Tanzania and on the Northern Kenya Bank. The results indicate slight differences in variations off the Northern Tanzanian shelf region and the Northern Kenya Bank. Such small variations might have local impacts on the human population through influencing primary productivity and fisheries. The coastal waters off Malindi indicate stronger variations, particularly in 1997 (cold SST) and 1998 (warm SST), than those off Tanga region. The SST anomalies seem to be associated with thermocline and sea surface height (SSH) off Malindi, while off Tanga they relate only to SSH. This information provides further understanding of parameters that may affect fishing activities in these regions and can be used for planning and management processes.","PeriodicalId":200681,"journal":{"name":"Western Indian Ocean journal of marine science","volume":"210 1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"114316788","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Age, growth and mortality of the anchovy Stolephorus commersonnii (Lacepède,1803) (Clupeiformes) caught off the coast of Tanga, Tanzania 坦桑尼亚Tanga海岸捕获的Stolephorus commersonnii (lacep<e:1>，1803)(长尾鱼目)的年龄、生长和死亡率

Western Indian Ocean journal of marine science Pub Date : 2021-02-11 DOI: 10.4314/WIOJMS.SI2020.1.9

A. T. Kamukuru, S. Mahongo, B. Sekadende, J. Sululu

{"title":"Age, growth and mortality of the anchovy Stolephorus commersonnii (Lacepède,1803) (Clupeiformes) caught off the coast of Tanga, Tanzania","authors":"A. T. Kamukuru, S. Mahongo, B. Sekadende, J. Sululu","doi":"10.4314/WIOJMS.SI2020.1.9","DOIUrl":"https://doi.org/10.4314/WIOJMS.SI2020.1.9","url":null,"abstract":"The population dynamics of Stolephorus commersonnii (Lacepede, 1803) from a ringnet fishery operating off the northern coast of Tanga Region were evaluated based on monthly length-frequency data collected from August 2016 to August 2017. The total length (TL) and total weight (TW) of 14,410 individuals ranged from 22 to 130 mm and from 0.39 to 14.64 g respectively. S. commersonnii exhibited a negative allometric growth pattern with the length-weight relationship model: W = 0.00001 x L2.886. The von Bertalanffy growth function was Lt = 86.03 x (1 – e–1.19(t – (–0.01))) using ELEFAN I from the FiSAT II software tool package. Growth performance index and longevity were estimated at (ɸ) = 3.9 and Tmax = 2.5 yrs, respectively. The total (Z), fishing (F) and natural (M) mortalities were determined at 1.39, 0.53 and 0.86 yr-1, respectively. The current exploitation rate (Ecur) was estimated at 0.38. S. commersonnii exhibited a year-round breeding pattern, with two recruitment peaks in March and June/July. Length-at-first-capture (Lc50) and length-at-first-sexual maturity (Lm50) were 40.51 and 57.35 mm TL, respectively, suggesting growth overfishing. The stock of anchovy indicates an overfishing scenario requiring management intervention such as reducing fishing effort levels, increasing mesh sizes and introducing seasonal closures during peak spawning periods.","PeriodicalId":200681,"journal":{"name":"Western Indian Ocean journal of marine science","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128974406","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1

Biophysical modelling of coastal upwelling variability and circulation along the Tanzanian and Kenyan coasts 坦桑尼亚和肯尼亚海岸沿岸上升流变异性和环流的生物物理模拟

Western Indian Ocean journal of marine science Pub Date : 2021-02-11 DOI: 10.4314/WIOJMS.SI2020.1.5

I. Halo, P. Sagero, M. Manyilizu, S. Mahongo

{"title":"Biophysical modelling of coastal upwelling variability and circulation along the Tanzanian and Kenyan coasts","authors":"I. Halo, P. Sagero, M. Manyilizu, S. Mahongo","doi":"10.4314/WIOJMS.SI2020.1.5","DOIUrl":"https://doi.org/10.4314/WIOJMS.SI2020.1.5","url":null,"abstract":"Ocean circulation, upwelling phenomena and chlorophyll-a concentrations were investigated within the framework of numerical model simulations with 1/12° nested horizontal grid-size, in the tropical western Indian Ocean, along the coasts of Tanzania and Kenya. Ekman driven upwelling exhibited high levels of spatial and temporal variability in the region, characterized by a more vigorous occurrence/intensification during the Northeast than the Southwest Monsoon season. A similar trend was observed for chlorophyll-a distribution, but with an additional strong contribution during the inter-monsoon period from March to April. Trend analysis of a SST-derived coastal upwelling index (CUI) computed over the Pemba Channel and offshore of the East African Coastal Current (EACC), for 24 years (1990 - 2013), revealed a general linear relation of the form CUI(yr) = 2.4x10-7yr – 285, with a steady small annual increase of the upwelling phenomena by 0.0024/year ≃ 4% during the whole period of the simulation, which could be attributed to documented increasing trends of wind intensity and water volume transport in the region. The CUI exhibited the two most dominant peaks of variabilities on the range of annual and semi-annual timescales. The wind-stress southward component and the easting/westing veering of the northward EACC at 6°S revealed that these parameters were moderate and significantly correlated with the CUI (r = - 0.53 and 0.52, p<0.05) respectively, further suggesting its intensification during the Northeast Monsoon season.","PeriodicalId":200681,"journal":{"name":"Western Indian Ocean journal of marine science","volume":"107 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131475014","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

Preliminary findings on the food and feeding dynamics of the anchovy Stolephorus commersonnii (Lacepède, 1803) and the Indian mackerel Rastrelliger kanagurta (Cuvier, 1817) from Tanga Region, Tanzania 坦桑尼亚Tanga地区鳀鱼Stolephorus commersonnii (lacep<e:1>， 1803年)和印度鲭鱼Rastrelliger kanagurta(居维叶，1817年)的食物和摄食动态的初步发现

Western Indian Ocean journal of marine science Pub Date : 2021-02-11 DOI: 10.4314/WIOJMS.SI2020.1.7

B. Sekadende, J. Sululu, A. T. Kamukuru, M. Igulu, S. Mahongo

{"title":"Preliminary findings on the food and feeding dynamics of the anchovy Stolephorus commersonnii (Lacepède, 1803) and the Indian mackerel Rastrelliger kanagurta (Cuvier, 1817) from Tanga Region, Tanzania","authors":"B. Sekadende, J. Sululu, A. T. Kamukuru, M. Igulu, S. Mahongo","doi":"10.4314/WIOJMS.SI2020.1.7","DOIUrl":"https://doi.org/10.4314/WIOJMS.SI2020.1.7","url":null,"abstract":"Small pelagic fishes play an important role in the ecosystem by linking planktonic production and higher trophic level predators, and provide a livelihood to both the small-scale and commercial fisher communities. This study analyzed the food and feeding habits of Stolephorus commersonnii (Lacepede, 1803) and Rastrelliger kanagurta (Cuvier, 1817) from the ring-net fishery in Tanga, Tanzania. A total of 1 434 and 320 stomachs of S. commersonnii and R. kanagurta respectively were examined for gut contents using the relative volumetric method. S. commersonnii was found to be a planktivorous carnivore, feeding principally on planktonic penaeid shrimps (48.6%), fish larvae (33.2%) and zooplankton (12.3%). R. kanagurta was found to be carnivorous, feeding predominantly on fish (60.6%), mainly S. commersonnii, while penaeid shrimps, juvenile fish, and juvenile stages of squids formed 26.5% of the total number of food items in R. kanagurta guts. Both S. commersonnii and R. kanagurta exhibited ontogenic diet shifts, where they fed exclusively on small prey as juveniles and consumed larger food items as they grew. The index of vacuity was higher in S. commersonnii (46.1%) than in R. kanagurta (16.6%). This study revealed the importance of penaeid shrimps as food for S. commersonnii, that in turn formed the main food for R. kanagurta. This implied that the two species were able to coexist in the same niche by avoiding interspecific competition for food.","PeriodicalId":200681,"journal":{"name":"Western Indian Ocean journal of marine science","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133233589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 2

Present and future trends in winds and SST off central East Africa 中非东部风和海温的现在和未来趋势

Western Indian Ocean journal of marine science Pub Date : 2021-02-11 DOI: 10.4314/WIOJMS.SI2020.1.6

M. García‐Reyes, S. Mahongo

{"title":"Present and future trends in winds and SST off central East Africa","authors":"M. García‐Reyes, S. Mahongo","doi":"10.4314/WIOJMS.SI2020.1.6","DOIUrl":"https://doi.org/10.4314/WIOJMS.SI2020.1.6","url":null,"abstract":"The coast of central East Africa (CEA) is a dynamic region in terms of climate, in which fisheries and marine-related services impact a large portion of the population. The main driver of regional dynamics is the seasonal alternation of the Northeast (NE) and Southeast (SE) monsoons. Winds associated with these monsoons modulate the prevalent, remotely-forced East African Coastal Current (EACC). Here, present and future trends in winds and sea surface temperature (SST) of the CEA and adjacent regions are investigated using reanalysis and reconstructed data, and an ensemble of General Circulation Models. It was found that the winds and SST show unidirectional trends, with magnitude and spatial differences between the NE and SE monsoons. Winds show weakening trends during the NE monsoon, in the past and future, of the Somali region; with no significant trends during the SE monsoon. SST shows increasing trends in the entire region in the past and future, with stronger warming during the NE monsoon off Somalia; SST trends are smaller in the CEA. These trends could impact the CEA through increased water-column stability and decreased upwelling due to shifting of the EACC separation from the continent. However, given the coarse resolution of data analyzed, regional modeling is still necessary to understand the impacts on local dynamics and productivity in the CEA.","PeriodicalId":200681,"journal":{"name":"Western Indian Ocean journal of marine science","volume":"64 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2021-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125340218","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 1