Immunomodulatory Effect of Moringa oleifera Lam. Aqueous Extract on the Burrowing Crab, Cardiosoma guanhumi (Latreille, 1828)

Moringa oleifera has impressive range of nutritional and medicinal values which when consumed have influence on hematological profile which is applied as an index of physiological condition of various organisms and thus provide information about the health status of local populations. The study aimed to determine the effects of M. oleifera aqueous leaves extract on the hematology, serum biochemical profile and antioxidant enzyme activities of the burrowing crab, Cardiosoma guanhumi. Thirty juveniles of C. guanhumi (Average weight 43.20±0.05 g) were tested, where six crabs were randomly selected and distributed per each tank (1 x 1x 0.6m3) of 1litre of water. Different diets containing M. oleifera aqueous extract at inclusion levels of 0.5 ml, 1.0 ml, 1.5 ml, 2.0 ml and control were used to feed the crabs. Total Haemocyte Count ranged between 2733.33±0.90 mL and 6350.00±0.60 mL; there were significant differences among the treatment groups (p < 0.05). Haemocyte sub-population variables showed that crabs fed the control and 2.0ml M. oleifera kg-1 diet had increased in the granulocyte and monocyte populations but a decrease in the agranulocytes. The results of the serum enzymes showed an increase as the level of M. oleifera aqueous extract increases in the diet. Highest superoxide dismutase (75.43 ±21.25 min/mg pro) and catalase activities (2.96±0.18 min/mg pro), malondialdehyde (12.05±2.09 nmol/L) and glutathione concentrations (0.19 ±0.02 μmol/L) were recorded in crabs fed diet T4 (2.0ml M. oleifera kg-1), while the lowest were obtained in crabs fed control diet. The present study showed that the inclusion of M. oleifera aqueous extract up to 1.0ml kg-1 will have immunomodulatory performance on Cardiosoma guanhumi without any deleterious effect on the crab’s health status. Keywords: Hemato-Biochemicals, Land Crab, Lagos Lagoon, Plant Extract, Nigeria

Burrowing crabs and physical factors hasten marsh recovery at panne edges

Salt marsh loss is projected to increase as sea-level rise accelerates with global climate change. Salt marsh loss occurs along both lateral creek and channel edges and in the marsh interior, when pannes expand and coalesce. Often, edge loss is attributed to erosive processes whereas dieback in the marsh interior is linked to excessive inundation or deposition of wrack. We conducted a two-year field experiment (2016-2018) in a central California estuary, where, immediately preceding our study, marsh dieback at creek edges and panne expansion occurred during a period of severe drought and an overlapping warm water event. Our study explored how an abundant burrowing crab, shown to have strong negative effects on marsh biomass near creek edges, affects panne dynamics. We also explored which panne attributes best predicted their dynamics. Overall, we found that pannes contracted during the study period, but with variable rates of marsh recovery across pannes. Our model incorporating both physical and biological factors explained 86% of the variation in panne contraction. The model revealed a positive effect of crab activity, sediment accretion, and a composite of depth and elevation on panne contraction, and a negative effect of panne size and distance to nearest panne. The positive crab effects detected in pannes contrast with negative effects we had earlier detected near creek edges, highlighting the context-dependence of top-down and bioturbation effects in marshes. As global change continues and the magnitude and frequency of disturbances increases, understanding the dynamics of marsh loss in the marsh interior as well as creek banks will be critical for the management of these coastal habitats.

Population structure of the burrowing crab Neohelice granulata (Brachyura, Varunidae) in a SW Atlantic salt marsh

Neohelice granulata inhabits estuarine and protected coastal areas in temperate regions, and is the most dominant decapod crustacean in the Bahía Blanca estuary. The population structure was studied during a year in a SW Atlantic salt marsh located in the Bahía Blanca estuary, Argentina. Crabs were sampled monthly from August 2010 to July 2011. The maximum observed density was 39 crabs/m2 in February and 70 burrows/m2 in May. The maximum carapace width (CW) in males was 32 mm and 27.5 mm in females. Medium size crabs were between 16 and 20 mm CW. Significantly smaller sized crabs were observed at the lower intertidal regions (p