The abiotic ecology of breeding ground of Palaemonid prawns in the Ilaje Estuary, Ondo State, Nigeria

In situ ecological assessment of the breeding grounds of palaemonid prawns was conducted in some selected locations around Ondo state coastal area between the months of April and September. Data obtained were subjected to both descriptive and inferential statistics. Three species of Palaemonid prawns were identified in four different locations within the study area with relative abundance ratio of 4:3:1. Macrobrachium macrobrachion, Nematopalaemon hastatus and Palaemon maculatus respectively. Sex ratio of 1 male to 5 females for M. macrobrachion, and 1 male to 2 females for N. hastatus and P. maculatus were observed with result showing significant relationships (P < 0.05) in distribution patterns across collection sites. Population distribution within the water column showed that palaemons are sub-lithoral prawns inhabiting maximum mean depth of 0.67m ± 0.025. Surface macro-phytes such as Eichhornia crassipies, Paspalum vaginatum, and Pistia stratiotes are common providing hiding spots for the prawn at the breeding ground. The mean soil pH across the sites stands at 6.67± 0.399 with the soil textural class that range from silty-loam to silty-clay. Also, the water quality parameters of study areas suggest that captive culture and rearing of Palaemons may be feasible outside the breeding areas

Seasonality Effect on Habitat Status of Macrobrachium prawns on a Section of Ogun-Osun River Basin Channel, Nigeria

The effect of seasonal changes on habitat conditions and biological well-being of Macrobrachium prawns on a section of Ogun-Osun River Basin Channel, Southwestern Nigeria was investigated between June, 2015 and April, 2017. Morphological characterization of specimens collected revealed two populations of prawns in the genus Macrobrachium (M. macrobrachion and M. vollenhovenii) foraging together on this location. The study revealed that there is no significant variation (P&gt;0.05) in the water quality parameters between seasons while sediment textural compositions vary significantly (P&gt;0.05) between seasons. M. macrobrachion were more abundant in rainy seasons while M. vollenhovenii were more in dry seasons. However, condition factor (k) of the two prawns was better in rainy seasons than dry seasons. Results from this study revealed that seasonality affects habitat compositions and biological well-being of Macrobrachium prawns. Consequently, scientific observations recorded in this study will serve as important references in cultivation, assessment and management of prawn fisheries. Key words: Habitat, Seasons, Macrobrachium prawns, Ogun-Osun River Basin Channel, Nigeria