The North Kenya Banks

Morgans, J. F. C.

doi:10.1038/184259b0

Cited by 10 publications

(3 citation statements)

References 2 publications

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“…These negative effects are probably localized close to discharge points and the total effect, on a larger spatial scale, is one of increased productivity. Discharge areas such as the Tana and Sabaki rivers have long been known as areas of good fishing and high productivity for tropical waters (Morgans 1959, Wickstead 1961, Iversen 1984, Venema 1984) and t h~s is undoubtably due to river discharge inputs and discharge-induced upwelling. There is no evidence to suggest that poor inland soil conservation practices are having a negative effect on fisheries or on coral reefs south of Malindi (Giesen & van de Kerkhof 1984), but a thorough study has yet to be completed.…”

Section: Fisheriesmentioning

confidence: 99%

Seasonality in East Africa's coastal waters

McClanahan¹

1988

Mar. Ecol. Prog. Ser.

249

155

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A review of existing literature and data on seasonal patterns in East Africa's coastal waters indicates distinct seasonality in physical, chemical and biological oceanographic parameters. Seasonal patterns are dictated by the behavior of the Inter-Tropical Convergence Zone (ITCZ) which creates 2 distinct seasonsthe northeast and southeast monsoons. SE monsoon (March to October) meteorological parameters are characterized by high cloud cover, rainfall, river discharge, terrestrial runoff and wind energy while solar insolation and temperatures are low; SE monsoon oceanographic parameters are characterized by cool water, a deep thermocline, high water-column mixing and wave energy, fast currents, low s a h~t y and high phosphorus. These parameters are reversed during the NE monsoon. Nitrogen availability and planktonic primary productivity are high along the Somali coast and estuarine and river discharge areas during the southeast monsoons due to nutrient upwelling and terrestrial runoff. In near-shore waters off Tanzania, nitrogen fixation is the major source of nitrogen and is highest during NE monsoons when the water column is stable. Coral reef benthic algal biomass and diversity is greatest during the SE monsoons. Fish catch and reproduction are highest during NE monsoons in Kenya and Tanzania. Transition periods between monsoons may also be important times in determining productivity and reproduction.

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Section: Fisheriesmentioning

confidence: 99%

Seasonality in East Africa's coastal waters

McClanahan¹

1988

Mar. Ecol. Prog. Ser.

249

155

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“…This exists further offshore over the North Kenya Banks (NKBs), and is operated by a small fleet of motorized boats (Maina , ). The NKBs, first described by Morgans (), are about 45 km wide and 180 km long extending from 1.4 to 3°S and from 40.5 to 41.5°W with water depths up to 125 m (Johnson et al, ). The NKBs, characterized by the area inside the 200‐m isobath, stand out relative to the narrow coastline of East Africa (Figure ).…”

Section: Introductionmentioning

confidence: 99%

“…The NKBs, characterized by the area inside the 200‐m isobath, stand out relative to the narrow coastline of East Africa (Figure ). As Kenya has one of the lowest marine catch rates among coastal African countries (Le Manach et al, ), this offshore area has been proposed as a region that could provide a boost to local fishery resources (Morgans , ; Wickstead , ). The increased utilization of motorized boats (Maina , ) will improve access to the NKBs, which could transform this region into an economically important fishery for the country (Akunga, ).…”

Section: Introductionmentioning

confidence: 99%

Shelf‐Break Upwelling and Productivity Over the North Kenya Banks: The Importance of Large‐Scale Ocean Dynamics

et al. 2020

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The North Kenya Banks (NKBs) have recently emerged as a new frontier for food security and could become an economically important fishery for Kenya with improved resources providing better accessibility. Little research has been done on the mechanisms supporting high fish productivity over the NKBs with information on annual and interannual environmental variability lacking. Here we use a high-resolution, global, biogeochemical ocean model with remote sensing observations to demonstrate that the ocean circulation exerts an important control on the productivity over the NKBs. During the Northeast Monsoon, which occurs from December to February, upwelling occurs along the Kenyan coast, which is topographically enhanced over the NKBs. Additionally, enhanced upwelling events, associated with widespread cool temperatures, elevated chlorophyll, nutrients, primary production, and phytoplankton biomass, can occur over this region. Eight such modeled events, characterized by primary production exceeding 1.3 g C/m −2 /day, were found to occur during January or February from 1993-2015. Even though the upwelling is always rooted to the NKBs, the position, spatial extent, and intensity of the upwelling exhibit considerable interannual variability. The confluence zone between the Somali Current and East African Coastal Current (referred to as the Somali-Zanzibar Confluence Zone) forms during the Northeast Monsoon and is highly variable. We present evidence that when the Somali-Zanzibar Confluence Zone is positioned further south, it acts to enhance shelf-edge upwelling and productivity over the NKBs. These findings provide the first indication of the environmental controls that need to be considered when developing plans for the sustainable exploitation of the NKB fishery. Plain Language SummaryThe North Kenya Banks (NKBs) have recently emerged as a region capable of sustaining a rich fishery, which would boost Kenya's economy. Little research has been conducted on the environmental controls that affect these fisheries and whether there is annual variability over multiple years. Here an ocean model is used, with satellite remote sensing data, to investigate how the ocean influences this region. Specifically, the convergence of two currents during the Northeast Monsoon, the Somali Current and the East African Coastal Current, which meet near the NKBs and flow away from the coast. This induces the upwelling of cold, nutrient-rich waters, which are brought up from depth to the surface, resulting in the NKBs being a highly productive area. The confluence of these two currents forms from December to February and its position along the Kenyan coast varies from year-to-year. This leads to considerable variability in the intensity, position, and spatial extent of productive waters. Productivity is enhanced over the NKBs when the confluence of the two currents is generally positioned further south. These findings provide the first indication of the environmental controls that need to be taken into account when developing plans for sust...

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Somatostatin-28- and somatostatin- 14-like immunoreactivities in the rat pituitary gland

et al. 1988

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Endogenous SS14- as well as SS28-like immunoreactive materials were detected in both male and female rats by radioimmunoassay and by immunocytochemistry on ultrathin frozen sections. The content of somatostatin-like immunoreactivity was 0.39 +/- 0.08 pg per mg adenohypophysis. Immunoreactivity was localized by immunocytochemistry in three pituitary cell types: somatotrophs, lactotrophs and thyrotrophs, but not in corticotrophs and gonadotrophs. In these three pituitary cell types the SS28- and the SS14-like immunoreactive materials were localized in the cytoplasm and in the nucleus. In the cytoplasm the immunoreactivity was seen in the cytoplasmic matrix and in the secretory granules. In the nucleus it was present mainly in the euchromatin close to the heterochromatin. In somatotrophs and lactotrophs, SS14- and SS28-like immunoreactive materials have been detected at the plasma membrane level. These results suggest that (1) endogenous SS14 and SS28 are present in adenohypophysis in somatotrophs, lactotrophs and thyrotrophs, and (2) the two peptides act on both the cytoplasmic components and the nucleus.

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The North Kenya Banks

Cited by 10 publications

References 2 publications

Seasonality in East Africa's coastal waters

Seasonality in East Africa's coastal waters

Shelf‐Break Upwelling and Productivity Over the North Kenya Banks: The Importance of Large‐Scale Ocean Dynamics

Somatostatin-28- and somatostatin- 14-like immunoreactivities in the rat pituitary gland

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