Western Indian Ocean Journal of Marine Science, Aug 13, 2019
Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wid... more Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wide dissemination of high quality research generated in the Western Indian Ocean (WIO) region, in particular on the sustainable use of coastal and marine resources. This is central to the goal of supporting and promoting sustainable coastal development in the region, as well as contributing to the global base of marine science. The journal publishes original research articles dealing with all aspects of marine science and coastal management. Topics include, but are not limited to: theoretical studies, oceanography, marine biology and ecology, fisheries, recovery and restoration processes, legal and institutional frameworks, and interactions/relationships between humans and the coastal and marine environment. In addition, Western Indian Ocean Journal of Marine Science features state-of-the-art review articles and short communications. The journal will, from time to time, consist of special issues on major events or important thematic issues.
Striped marlin Kajikia audax are globally Near Threatened and their stock in the Indian Ocean was... more Striped marlin Kajikia audax are globally Near Threatened and their stock in the Indian Ocean was last assessed as "overfished and subject to overfishing". Significant gaps in our understanding of their ecology remain, hampering the efforts of fisheries managers to ensure stock sustainability. There is a particular lack of fisheries-independent data. Here we present the results from the first large-scale satellite tracking study of K. audax in the Indian Ocean. We tagged 49 K. audax with pop-up archival satellite-linked tags off the Kenyan coast from 2015-2019. Individuals were highly mobile, covering horizontal distances of up to 9,187 km over periods ranging up to 183 days, with a mean daily distance of ~48 km. Long-distance movements were recorded to the east and north of East Africa, with the most distant tracks extending north to the Arabian Sea and east to near the Maldives. None of the K. audax swam south of East Africa. Kernel utilisation distributions of fish locations demonstrated their shifting seasonal activity hotspots. Over the sport-fishing season (and tagging period) in Kenya, from Dec-Mar, K. audax typically stayed off the East African coast. After March, the activity hotspot shifted north to a region close to the Horn of Africa and Socotra Island. Remotely-sensed sea surface temperature and chlorophyll-a maps indicated that this seasonal movement could be driven by a shift in prey availability. Our results show the high mobility of K. audax in the Western Indian Ocean, and that individuals seasonally range between two major fishing areas.
Experimental trawl surveys were conducted to determine effective tow durations for estimating fis... more Experimental trawl surveys were conducted to determine effective tow durations for estimating fish and shellfish abundances in deeper-water bottom trawl surveys. A total of 304 hauls were conducted in Kagoshima Bay, southern Japan, for preset tow durations of 10 and 20 min, using a simple trawl net fitted with depth loggers. Towing durations were recorded at the ship's bridge based on the shooting, towing and hauling times of the trawl net, using pre-established warp lengths for different water depths. Effective tow durations were computed by plotting depth logger and echo sounder data against tow time, and compared with preset tow durations. Trawled distances and swept areas were calculated using the Euclidean distance method. Effective tow durations ranged from 9 to 23 and from 19 to 37 for the 10 and 20 min preset tow durations, respectively. Preset tow duration estimations for abundance were highly biased: −10 to 130% and −5 to 85% biases relative to the effective tow duration estimations, respectively. Moreover, the biases were more pronounced in the shorter tow durations in deeper-water trawl hauls. The computation of effective tow durations using depth loggers and the ship's onboard instrumentation presents a simple approach for correcting inadvertent estimations of effective tow duration, swept area and abundance indices.
The present study provides a characterization of water quality and plankton samples in earthen fi... more The present study provides a characterization of water quality and plankton samples in earthen fish pond in Rajshahi, Bangladesh. Sampling was done over a period of six months, running from October, 2004 through March, 2005. All the water quality parameters were within the optimal ranges for plankton productivity. Temperatures varied from 19.75 to 27.25°C; transparency, 24.75-29.50 cm; pH, 6.62-7.85; Dissolved Oxygen (DO), 3.87-5.85 mg L-1 ; free CO 2, 5.25-7.25 mg L-1 and bicarbonate (HCO 3) alkalinity, 81.25-147.5 mg L-1. Analyses of plankton samples recorded a total of 5 classes phytoplankton viz.; Bacillariophyceae, Chlorophyceae, Cyanophyceae, Dinophyceae, Euglenophyceae and 2 classes of zooplankton; Crustacea and Rotifera. The phytoplankton population was comprised of 17 genera belonging to Cyanophyceae (5 classes, 34.47%), Bacillariophyceae (3, 13.87%), Cyanophyceae (3, 34.48%), Euglenophyceae (3, 10.68%) and 1 to Dinophyceae (6.50%). The zooplankton population consisted of 10 genera belonging to Rotifera (4, 40.13%) and Crustacea (6, 59.87%). Phytoplankton and zooplankton abundance varied from 60800 to 239400 units/1 and 7620 to12160 units/1, respectively. It is concluded that the phytoplankton groups provide the main support for earthen pond aquaculture in the pond compared to zooplankton classes. The information provides for more research to compare water quality and pond plankton characteristics in earthen aquaculture systems with and without fish stocking. Further studies on the seasonal changes of water quality parameters and its effects on plankton production in the fish ponds and all year extended monitoring is recommended in future studies.
The Epinephelus genus grouper fishers (family: Serranidae) are among the most important sources o... more The Epinephelus genus grouper fishers (family: Serranidae) are among the most important sources of food and revenue to the local artisanal grouper fishers in Kenya. However, the fishery seems to be operating below maximum sustainable yield levels and their thorough distribution and reproductive patterns knowledge is required for development of management interventions to protect this important fishery. Their distribution and reproductive patterns was therefore investigated for a period of 8 months from December, 2013 to July, 2014 in the Kenyan south coast inshore marine waters of Vanga, Shimoni and Msambweni. Data was collected from these fishing grounds artisanal fishery landings and the species distribution and reproductive patterns validated through experimental underwater visual surveys, species abundance landings, diversity and maturity stages. A total of 30 species dominated by Epinephelus fasciatus landings were recorded with most showing narrow distribution patterns. Only E. fasciatus, E. malabaricus, E. longispinis, E. chlorostigma, E. coeruleopunctatus, E. multinotatus, E. merra, E. melanostigma, E. tukula, E. fuscoguttatus and E. tauvina had wider distributions. Eighteen had increased reproductive activity from April-July during southeast monsoon season suggesting the need for restricted fishing seasons. Further species habitat preference studies are also required to provide conservation and ecosystem protection information data.
The small indigenous species, namely Ailiichthys punctata (Day, 1871), Botia lohachata (Chaudhuri... more The small indigenous species, namely Ailiichthys punctata (Day, 1871), Botia lohachata (Chaudhuri, 1912), Chanda nama (Hamilton, 1822), Laubuca laubuca (Hamilton, 1822) and Mystus cavasius (Hamilton, 1822), comprise an important component of riverine fisheries of Bangladesh. This study describes the length–weight relationships (LWRs) and length– length relationships (LLRs) of five threatened fishes from the Jamuna River, a distributary of the Brahmaputra River in northern Bangladesh. A total of 919 specimens from five species in five families used for this study were caught by traditional fishing gear, March 2010 through February 2011. The allometric coefficient (b) of the LWRs indicated negative allometric growth in A. punctata, B. lohachata, and C. nama (b < 3.00), but positive allometric growth in L. laubuca and M. cavasius (b > 3.00). Furthermore, the LLRs were highly correlated (r2 > 0.978; P < 0.001). This study presents the first reference on LWRs and LLRs for the...
This paper is presented well and presented very good data of available Macrobrachium species in B... more This paper is presented well and presented very good data of available Macrobrachium species in Bangladesh, and their production since last 14 years, which would be very effective for further sustainable management of this shrimp fishery in Bangladesh as well as neighboring countries.
The Asian Silurid catfish Wallago attu is an endangered species. Populations are declining due to... more The Asian Silurid catfish Wallago attu is an endangered species. Populations are declining due to over-exploitation, pollution and environmental degradation. Law enforcement to ban destructive fishing practices should be enhanced for the conservation of the populations. Keywords Asian silurid catfish. Endangered. Establishment of sanctuaries Common names: Asian Silurid Catfish (Fig. 1). Conservation status: Endangered (Kurup 1992; Mijkherjee et al. 2002). Identification: Body is elongate and laterally compressed, with a nearly straight dorsal profile. The snout is depressed. Mouth is deeply cleft and maxilla extends behind the eyes and lower jaws slightly longer. Dorsal fin is small, spineless and situated above the last half of pectoral. D.5; P1.1/13-14; P2.10; A. 82-89. Distributions: It is widely distributed in the Indian subcontinent countries,
The rabbitfishes (Pisces: Siganidae) have long been considered good candidates for aquaculture. S... more The rabbitfishes (Pisces: Siganidae) have long been considered good candidates for aquaculture. Some biological attributes including morphometric relationships (length-length, length-weight) and condition factors of three siganids of the Western Indian Ocean were estimated over peak April-August monsoon season in Southcoast Kenya. Specimens were caught using basket traps "malema", one of the main gears in the traditional fishery. A total of 64, 260 and 736 specimens of Siganus stellatus, S. canaliculatus and S. sutor were recorded, with mean±standard error for total length (TL) as 16.0±0.6cm, 22.5±0.3cm and 26.5±0.2cm with corresponding wet body weights (BWs) of 71.28±8.53g, 158.58±6.45g and 258.80±4.30g respectively. TL-BW relationships were best expressed by log 10 BW=2.597log 10 TL-1.356 for S. stellatus, log 10 BW=2.800log 10 TL-1.635 for S. canaliculatus and log 10 BW=2.716log 10 TL-1.484 for S. sutor with relative condition factors expressed by Kn = BW/ [(4.41x10-2) (TL 2.597)], Kn = BW/ [(2.32x10-2) (TL 2.800)] and Kn = BW/ [(3.28x10-2) (TL 2.716)] for the three species respectively. TL and BW were significantly correlated with Kn and K. To the best knowledge of the authors, this study provides the first L-W relationship and Kn data for S. stellatus within the species geographical distribution. The overall results and equations provide useful simple tools for in-situ gauging of overall health of wild siganid populations in Southcoast Kenya for fisheries management and assessment of potential aquaculture species.
The rabbitfishes (Pisces: Siganidae) have long been considered good candidates for aquaculture. S... more The rabbitfishes (Pisces: Siganidae) have long been considered good candidates for aquaculture. Some biological attributes including morphometric relationships (length-length, length-weight) and condition factors of three siganids of the Western Indian Ocean were estimated over peak April-August monsoon season in Southcoast Kenya. Specimens were caught using basket traps "malema", one of the main gears in the traditional fishery. A total of 64, 260 and 736 specimens of Siganus stellatus, S. canaliculatus and S. sutor were recorded, with mean±standard error for total length (TL) as 16.0±0.6cm, 22.5±0.3cm and 26.5±0.2cm with corresponding wet body weights (BWs) of 71.28±8.53g, 158.58±6.45g and 258.80±4.30g respectively. TL-BW relationships were best expressed by log10BW=2.597log10TL-1.356 for S. stellatus, log10BW=2.800log10TL-1.635 for S. canaliculatus and log10BW=2.716log10TL-1.484 for S. sutor with relative condition factors expressed by Kn = BW/ [(4.41x10 -2 ) (TL
Plant Biosystems - An International Journal Dealing with all Aspects of Plant Biology, 2020
The coastal forests of Kenya are global biodiversity hotspots known for rich plant diversity and ... more The coastal forests of Kenya are global biodiversity hotspots known for rich plant diversity and endemism. They exist as fragmented forest islands, and their current conservation status and quantitative trends in plant diversity are understudied. We investigated these knowledge gaps by providing a comprehensive literature review and comparing to field data collected using standardized sampling protocol. Our goals were to build a robust basis for future analyses, biodiversity monitoring, and to understand the role of fragment area in determining species richness. We recorded a total of 937 woody species belonging to 88 families in 30 forest patches from reviewed and sampled data. Species richness per site from literature review was affected by biases in data scarcity, forest size and variation in sampling methods. In general, large forests reserves of Shimba hills and Arabuko exhibited a high number of cumulative species compared to smaller forest patches. Species-area relationship s...
The seasonal abundance, dynamics and composition of the filamentous Cyanobacteria Planktothrix sp... more The seasonal abundance, dynamics and composition of the filamentous Cyanobacteria Planktothrix spp. was studied over a 1-year period in two storm-water-fed earthen fishponds in Rajshahi city, northwestern Bangladesh. Sampling was conducted monthly using plankton net (25 μm mesh size) and the samples preserved in 5% formalin. Water quality parameters including water temperature, transparency, pH, dissolved oxygen (DO), biological oxygen demand (BOD), free carbon dioxide (CO2), nitrite-nitrogen (NO2-N), nitrate-nitrogen (NO3-N), ammonium (NH4 +), oxidation reduction index (rH2) were recorded during each sampling. Two species; Planktothrix agardhii and Planktothrix rubescens were identified during the study with P. agardhii recording higher abundance (p<0.05) all year round. The Planktothrix cell density was highest during March: 3.06×106 cells/L and 1.23×106 cells/L in Pond-1 and 2, respectively. The abundance of P. agardhii was relatively higher in spring. The cell densities incre...
The small indigenous species namely Ailiichthys punctata (Day 1871), Botia lohachata (Chaudhuri 1... more The small indigenous species namely Ailiichthys punctata (Day 1871), Botia lohachata (Chaudhuri 1912), Chanda nama (Hamilton 1822), Laubuca laubuca (Hamilton 1822) and Mystus cavasius (Hamilton 1822) comprise an important component of riverine fisheries of Bangladesh. But the natural populations are decreasing fast due to high fishing pressure as well as environmental degradation. Therefore, data and information is needed to avert the alarming decline and initiate conservation measures for these important fishes of the Jamuna River. This study describes the condition- (Fulton’s and Relative weight) and form-factor (a3.0) of the five threatened fishes from the Jamuna River, a distributary of the Brahmaputra River in northern Bangladesh. A total of 919 specimens from five species in five families used for this study were caught by traditional fishing gear during March 2010 through February 2011. For each individual, the total (TL), fork (FL) and standard (SL) length were measured by d...
Swabbing scat samples is a simple, non-invasive method of obtaining DNA samples for population ge... more Swabbing scat samples is a simple, non-invasive method of obtaining DNA samples for population genetic analysis of wild elephants. In this study, swab samples were taken from the scat of African savannah elephants inhabiting the Galana Wildlife Conservancy (GWC), bordering Tsavo East National Park in south-east Kenya. The swab samples were dried with silica as opposed to traditional methods of preservation in liquid or freezing while in the field. Furthermore, this study examined the rate of DNA degradation in scat samples in semi-arid conditions, typical of the GWC, by repeated sampling of scat in the field following deposition at defined time intervals over a period of two weeks. Results showed that both nuclear DNA (nDNA) and mitochondrial DNA (mtDNA) could be successfully amplified from scat samples up to 128 hours (about five days) following deposition. Significantly better results were obtained from samples taken from the outside of the scat than from the centre. Mitochondrial...
Noninvasive DNA sampling provides a way to sample wild mammal populations without causing harm or... more Noninvasive DNA sampling provides a way to sample wild mammal populations without causing harm or stress to the target animal, while also being safer and logistically simpler for the researcher. In addition, it is often easier to obtain permits for noninvasive sampling than for studies that require physical interaction with the animal, in particular with threatened or endangered species. Sampling noninvasively implies a DNA collection method that does not require capturing or disturbing the target animal, with examples such as collecting hair (Rovang, Nielsen, & Stenhouse, 2015) to the more common approach of collecting and preserving scat (Hassanin,
Western Indian Ocean Journal of Marine Science, Aug 13, 2019
Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wid... more Aims and scope: The Western Indian Ocean Journal of Marine Science provides an avenue for the wide dissemination of high quality research generated in the Western Indian Ocean (WIO) region, in particular on the sustainable use of coastal and marine resources. This is central to the goal of supporting and promoting sustainable coastal development in the region, as well as contributing to the global base of marine science. The journal publishes original research articles dealing with all aspects of marine science and coastal management. Topics include, but are not limited to: theoretical studies, oceanography, marine biology and ecology, fisheries, recovery and restoration processes, legal and institutional frameworks, and interactions/relationships between humans and the coastal and marine environment. In addition, Western Indian Ocean Journal of Marine Science features state-of-the-art review articles and short communications. The journal will, from time to time, consist of special issues on major events or important thematic issues.
Striped marlin Kajikia audax are globally Near Threatened and their stock in the Indian Ocean was... more Striped marlin Kajikia audax are globally Near Threatened and their stock in the Indian Ocean was last assessed as "overfished and subject to overfishing". Significant gaps in our understanding of their ecology remain, hampering the efforts of fisheries managers to ensure stock sustainability. There is a particular lack of fisheries-independent data. Here we present the results from the first large-scale satellite tracking study of K. audax in the Indian Ocean. We tagged 49 K. audax with pop-up archival satellite-linked tags off the Kenyan coast from 2015-2019. Individuals were highly mobile, covering horizontal distances of up to 9,187 km over periods ranging up to 183 days, with a mean daily distance of ~48 km. Long-distance movements were recorded to the east and north of East Africa, with the most distant tracks extending north to the Arabian Sea and east to near the Maldives. None of the K. audax swam south of East Africa. Kernel utilisation distributions of fish locations demonstrated their shifting seasonal activity hotspots. Over the sport-fishing season (and tagging period) in Kenya, from Dec-Mar, K. audax typically stayed off the East African coast. After March, the activity hotspot shifted north to a region close to the Horn of Africa and Socotra Island. Remotely-sensed sea surface temperature and chlorophyll-a maps indicated that this seasonal movement could be driven by a shift in prey availability. Our results show the high mobility of K. audax in the Western Indian Ocean, and that individuals seasonally range between two major fishing areas.
Experimental trawl surveys were conducted to determine effective tow durations for estimating fis... more Experimental trawl surveys were conducted to determine effective tow durations for estimating fish and shellfish abundances in deeper-water bottom trawl surveys. A total of 304 hauls were conducted in Kagoshima Bay, southern Japan, for preset tow durations of 10 and 20 min, using a simple trawl net fitted with depth loggers. Towing durations were recorded at the ship's bridge based on the shooting, towing and hauling times of the trawl net, using pre-established warp lengths for different water depths. Effective tow durations were computed by plotting depth logger and echo sounder data against tow time, and compared with preset tow durations. Trawled distances and swept areas were calculated using the Euclidean distance method. Effective tow durations ranged from 9 to 23 and from 19 to 37 for the 10 and 20 min preset tow durations, respectively. Preset tow duration estimations for abundance were highly biased: −10 to 130% and −5 to 85% biases relative to the effective tow duration estimations, respectively. Moreover, the biases were more pronounced in the shorter tow durations in deeper-water trawl hauls. The computation of effective tow durations using depth loggers and the ship's onboard instrumentation presents a simple approach for correcting inadvertent estimations of effective tow duration, swept area and abundance indices.
The present study provides a characterization of water quality and plankton samples in earthen fi... more The present study provides a characterization of water quality and plankton samples in earthen fish pond in Rajshahi, Bangladesh. Sampling was done over a period of six months, running from October, 2004 through March, 2005. All the water quality parameters were within the optimal ranges for plankton productivity. Temperatures varied from 19.75 to 27.25°C; transparency, 24.75-29.50 cm; pH, 6.62-7.85; Dissolved Oxygen (DO), 3.87-5.85 mg L-1 ; free CO 2, 5.25-7.25 mg L-1 and bicarbonate (HCO 3) alkalinity, 81.25-147.5 mg L-1. Analyses of plankton samples recorded a total of 5 classes phytoplankton viz.; Bacillariophyceae, Chlorophyceae, Cyanophyceae, Dinophyceae, Euglenophyceae and 2 classes of zooplankton; Crustacea and Rotifera. The phytoplankton population was comprised of 17 genera belonging to Cyanophyceae (5 classes, 34.47%), Bacillariophyceae (3, 13.87%), Cyanophyceae (3, 34.48%), Euglenophyceae (3, 10.68%) and 1 to Dinophyceae (6.50%). The zooplankton population consisted of 10 genera belonging to Rotifera (4, 40.13%) and Crustacea (6, 59.87%). Phytoplankton and zooplankton abundance varied from 60800 to 239400 units/1 and 7620 to12160 units/1, respectively. It is concluded that the phytoplankton groups provide the main support for earthen pond aquaculture in the pond compared to zooplankton classes. The information provides for more research to compare water quality and pond plankton characteristics in earthen aquaculture systems with and without fish stocking. Further studies on the seasonal changes of water quality parameters and its effects on plankton production in the fish ponds and all year extended monitoring is recommended in future studies.
The Epinephelus genus grouper fishers (family: Serranidae) are among the most important sources o... more The Epinephelus genus grouper fishers (family: Serranidae) are among the most important sources of food and revenue to the local artisanal grouper fishers in Kenya. However, the fishery seems to be operating below maximum sustainable yield levels and their thorough distribution and reproductive patterns knowledge is required for development of management interventions to protect this important fishery. Their distribution and reproductive patterns was therefore investigated for a period of 8 months from December, 2013 to July, 2014 in the Kenyan south coast inshore marine waters of Vanga, Shimoni and Msambweni. Data was collected from these fishing grounds artisanal fishery landings and the species distribution and reproductive patterns validated through experimental underwater visual surveys, species abundance landings, diversity and maturity stages. A total of 30 species dominated by Epinephelus fasciatus landings were recorded with most showing narrow distribution patterns. Only E. fasciatus, E. malabaricus, E. longispinis, E. chlorostigma, E. coeruleopunctatus, E. multinotatus, E. merra, E. melanostigma, E. tukula, E. fuscoguttatus and E. tauvina had wider distributions. Eighteen had increased reproductive activity from April-July during southeast monsoon season suggesting the need for restricted fishing seasons. Further species habitat preference studies are also required to provide conservation and ecosystem protection information data.
The small indigenous species, namely Ailiichthys punctata (Day, 1871), Botia lohachata (Chaudhuri... more The small indigenous species, namely Ailiichthys punctata (Day, 1871), Botia lohachata (Chaudhuri, 1912), Chanda nama (Hamilton, 1822), Laubuca laubuca (Hamilton, 1822) and Mystus cavasius (Hamilton, 1822), comprise an important component of riverine fisheries of Bangladesh. This study describes the length–weight relationships (LWRs) and length– length relationships (LLRs) of five threatened fishes from the Jamuna River, a distributary of the Brahmaputra River in northern Bangladesh. A total of 919 specimens from five species in five families used for this study were caught by traditional fishing gear, March 2010 through February 2011. The allometric coefficient (b) of the LWRs indicated negative allometric growth in A. punctata, B. lohachata, and C. nama (b < 3.00), but positive allometric growth in L. laubuca and M. cavasius (b > 3.00). Furthermore, the LLRs were highly correlated (r2 > 0.978; P < 0.001). This study presents the first reference on LWRs and LLRs for the...
This paper is presented well and presented very good data of available Macrobrachium species in B... more This paper is presented well and presented very good data of available Macrobrachium species in Bangladesh, and their production since last 14 years, which would be very effective for further sustainable management of this shrimp fishery in Bangladesh as well as neighboring countries.
The Asian Silurid catfish Wallago attu is an endangered species. Populations are declining due to... more The Asian Silurid catfish Wallago attu is an endangered species. Populations are declining due to over-exploitation, pollution and environmental degradation. Law enforcement to ban destructive fishing practices should be enhanced for the conservation of the populations. Keywords Asian silurid catfish. Endangered. Establishment of sanctuaries Common names: Asian Silurid Catfish (Fig. 1). Conservation status: Endangered (Kurup 1992; Mijkherjee et al. 2002). Identification: Body is elongate and laterally compressed, with a nearly straight dorsal profile. The snout is depressed. Mouth is deeply cleft and maxilla extends behind the eyes and lower jaws slightly longer. Dorsal fin is small, spineless and situated above the last half of pectoral. D.5; P1.1/13-14; P2.10; A. 82-89. Distributions: It is widely distributed in the Indian subcontinent countries,
The rabbitfishes (Pisces: Siganidae) have long been considered good candidates for aquaculture. S... more The rabbitfishes (Pisces: Siganidae) have long been considered good candidates for aquaculture. Some biological attributes including morphometric relationships (length-length, length-weight) and condition factors of three siganids of the Western Indian Ocean were estimated over peak April-August monsoon season in Southcoast Kenya. Specimens were caught using basket traps "malema", one of the main gears in the traditional fishery. A total of 64, 260 and 736 specimens of Siganus stellatus, S. canaliculatus and S. sutor were recorded, with mean±standard error for total length (TL) as 16.0±0.6cm, 22.5±0.3cm and 26.5±0.2cm with corresponding wet body weights (BWs) of 71.28±8.53g, 158.58±6.45g and 258.80±4.30g respectively. TL-BW relationships were best expressed by log 10 BW=2.597log 10 TL-1.356 for S. stellatus, log 10 BW=2.800log 10 TL-1.635 for S. canaliculatus and log 10 BW=2.716log 10 TL-1.484 for S. sutor with relative condition factors expressed by Kn = BW/ [(4.41x10-2) (TL 2.597)], Kn = BW/ [(2.32x10-2) (TL 2.800)] and Kn = BW/ [(3.28x10-2) (TL 2.716)] for the three species respectively. TL and BW were significantly correlated with Kn and K. To the best knowledge of the authors, this study provides the first L-W relationship and Kn data for S. stellatus within the species geographical distribution. The overall results and equations provide useful simple tools for in-situ gauging of overall health of wild siganid populations in Southcoast Kenya for fisheries management and assessment of potential aquaculture species.
The rabbitfishes (Pisces: Siganidae) have long been considered good candidates for aquaculture. S... more The rabbitfishes (Pisces: Siganidae) have long been considered good candidates for aquaculture. Some biological attributes including morphometric relationships (length-length, length-weight) and condition factors of three siganids of the Western Indian Ocean were estimated over peak April-August monsoon season in Southcoast Kenya. Specimens were caught using basket traps "malema", one of the main gears in the traditional fishery. A total of 64, 260 and 736 specimens of Siganus stellatus, S. canaliculatus and S. sutor were recorded, with mean±standard error for total length (TL) as 16.0±0.6cm, 22.5±0.3cm and 26.5±0.2cm with corresponding wet body weights (BWs) of 71.28±8.53g, 158.58±6.45g and 258.80±4.30g respectively. TL-BW relationships were best expressed by log10BW=2.597log10TL-1.356 for S. stellatus, log10BW=2.800log10TL-1.635 for S. canaliculatus and log10BW=2.716log10TL-1.484 for S. sutor with relative condition factors expressed by Kn = BW/ [(4.41x10 -2 ) (TL
Plant Biosystems - An International Journal Dealing with all Aspects of Plant Biology, 2020
The coastal forests of Kenya are global biodiversity hotspots known for rich plant diversity and ... more The coastal forests of Kenya are global biodiversity hotspots known for rich plant diversity and endemism. They exist as fragmented forest islands, and their current conservation status and quantitative trends in plant diversity are understudied. We investigated these knowledge gaps by providing a comprehensive literature review and comparing to field data collected using standardized sampling protocol. Our goals were to build a robust basis for future analyses, biodiversity monitoring, and to understand the role of fragment area in determining species richness. We recorded a total of 937 woody species belonging to 88 families in 30 forest patches from reviewed and sampled data. Species richness per site from literature review was affected by biases in data scarcity, forest size and variation in sampling methods. In general, large forests reserves of Shimba hills and Arabuko exhibited a high number of cumulative species compared to smaller forest patches. Species-area relationship s...
The seasonal abundance, dynamics and composition of the filamentous Cyanobacteria Planktothrix sp... more The seasonal abundance, dynamics and composition of the filamentous Cyanobacteria Planktothrix spp. was studied over a 1-year period in two storm-water-fed earthen fishponds in Rajshahi city, northwestern Bangladesh. Sampling was conducted monthly using plankton net (25 μm mesh size) and the samples preserved in 5% formalin. Water quality parameters including water temperature, transparency, pH, dissolved oxygen (DO), biological oxygen demand (BOD), free carbon dioxide (CO2), nitrite-nitrogen (NO2-N), nitrate-nitrogen (NO3-N), ammonium (NH4 +), oxidation reduction index (rH2) were recorded during each sampling. Two species; Planktothrix agardhii and Planktothrix rubescens were identified during the study with P. agardhii recording higher abundance (p<0.05) all year round. The Planktothrix cell density was highest during March: 3.06×106 cells/L and 1.23×106 cells/L in Pond-1 and 2, respectively. The abundance of P. agardhii was relatively higher in spring. The cell densities incre...
The small indigenous species namely Ailiichthys punctata (Day 1871), Botia lohachata (Chaudhuri 1... more The small indigenous species namely Ailiichthys punctata (Day 1871), Botia lohachata (Chaudhuri 1912), Chanda nama (Hamilton 1822), Laubuca laubuca (Hamilton 1822) and Mystus cavasius (Hamilton 1822) comprise an important component of riverine fisheries of Bangladesh. But the natural populations are decreasing fast due to high fishing pressure as well as environmental degradation. Therefore, data and information is needed to avert the alarming decline and initiate conservation measures for these important fishes of the Jamuna River. This study describes the condition- (Fulton’s and Relative weight) and form-factor (a3.0) of the five threatened fishes from the Jamuna River, a distributary of the Brahmaputra River in northern Bangladesh. A total of 919 specimens from five species in five families used for this study were caught by traditional fishing gear during March 2010 through February 2011. For each individual, the total (TL), fork (FL) and standard (SL) length were measured by d...
Swabbing scat samples is a simple, non-invasive method of obtaining DNA samples for population ge... more Swabbing scat samples is a simple, non-invasive method of obtaining DNA samples for population genetic analysis of wild elephants. In this study, swab samples were taken from the scat of African savannah elephants inhabiting the Galana Wildlife Conservancy (GWC), bordering Tsavo East National Park in south-east Kenya. The swab samples were dried with silica as opposed to traditional methods of preservation in liquid or freezing while in the field. Furthermore, this study examined the rate of DNA degradation in scat samples in semi-arid conditions, typical of the GWC, by repeated sampling of scat in the field following deposition at defined time intervals over a period of two weeks. Results showed that both nuclear DNA (nDNA) and mitochondrial DNA (mtDNA) could be successfully amplified from scat samples up to 128 hours (about five days) following deposition. Significantly better results were obtained from samples taken from the outside of the scat than from the centre. Mitochondrial...
Noninvasive DNA sampling provides a way to sample wild mammal populations without causing harm or... more Noninvasive DNA sampling provides a way to sample wild mammal populations without causing harm or stress to the target animal, while also being safer and logistically simpler for the researcher. In addition, it is often easier to obtain permits for noninvasive sampling than for studies that require physical interaction with the animal, in particular with threatened or endangered species. Sampling noninvasively implies a DNA collection method that does not require capturing or disturbing the target animal, with examples such as collecting hair (Rovang, Nielsen, & Stenhouse, 2015) to the more common approach of collecting and preserving scat (Hassanin,
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