Update README.md

README.md

@@ -2,7 +2,11 @@
 A spatially explicit (1D) individual-based model for shovelnose sturgeon populations in a tributary of the Missouri River system
 
 ## Description 
-SEIBMRiverFish is a spatially explicit, indvidual-based model designed to simulate population dynamics of shovelnose sturgeon via individual-based processes including movement, foraging, growth, metabolism, maturation, reproduction, and mortality in a large river system.   
+SEIBMRiverFish is a spatially explicit, individual-based model designed to simulate population dynamics of shovelnose sturgeon via individual-based processes including movement, foraging, growth, metabolism, maturation, reproduction, and mortality in a large river system.
+
+The sturgeon biophysical model simulates sturgeon population dynamics with two types of entities: river and sturgeon. The model river consists of 162 equally divided longitudinal rectangular segments (i.e. 1 river kilometre (rkm) each, where rkm is a measure of distance along a river) with six state variables: daily, depth-averaged discharge (m3);meandepth (gauge height; m); channel width (m); benthic invertebrate prey density (g m2); water temperature (degree-C); and photoperiod (h). Discharge, depth, width and prey density are spatially explicit, whereas temperature and photoperiod are spatially uniform. The sturgeon model keeps track of state variables of the entire life cycle. Early life stages (fertilised eggs, yolk-sac larvae, feeding larvae, and age-0 juveniles) are represented as superindividuals, whereas age-1þ juveniles and adultsare represented asindividualfish.Eachsuperindividualisa collection of individuals (‘cohorts’) from the same mother. The modelhas11statevariables:bodylength(mm),storagemass(g), structuralmass(g),gonadalmass(g),thenumberofindividualsin each superindividual, maturity status, reproductive status, physiological condition (the index of physiological condition,sex, age and longitudinal location in the river (rkm). 
+
+The model simulates the sturgeon population and updates state variables at discrete daily time steps over years and generations. The river habitat conditions are first updated, and the model then evaluates actions by sturgeon in the following order: (1) spawning, (2) hatching and larval development, (3) movement, (4) foraging, (5) growth and (6) mortality. The model updates state variables at the end of each action. At the beginning of each year, maturity is evaluated and, if mature sturgeon are healthy, they enter the reproductive cycle. Spawning normally occurs from late spring to early summer in the study system.
 
 ## References
 Goto, D., M. J. Hamel, J. J. Hammen, M. L. Rugg, M.A. Pegg, and V.E. Forbes. 2015. [Spatiotemporal variation in flow-dependent recruitment of long-lived riverine fish: Model development and evaluation](https://www.sciencedirect.com/science/article/abs/pii/S0304380014004992). Ecological Modelling. 296: 79–92. doi:10.1016/j.ecolmodel.2014.10.026