Nates and Felder: Growth and maturation of Lepidophthalmus sinuensis 



527 



1971; Poore and Suchanek, 1988; Witbaard and 

 Duineveld. 1989; Tamaki and Ingole, 1993; Rowden 

 and Jones, 1994, 1995; Dumbauld et al., 1996), and 

 the importance of callianassids in sediment turnover 

 and nutrient cycling has been noted (Rowden and 

 Jones, 1993; Ziebis et al., 1996). Ecological impacts 

 oi Lepidophthalmus spp. can dominate those of other 

 estuarine infauna, as noted in recent studies of the 

 warm-temperate species L. louisianensis in the 

 northern Gulf of Mexico (Felder and Lovett, 1989; 

 Felder and Griffis, 1994) and the tropical species L. 

 sinuensis on the Caribbean coast of Colombia (Nates 

 and Felder, 1998). Larval life histories for both L. 

 louisianensis and L. sinuensis have been described 

 (Nates et al., 1997), but later life stages and matura- 

 tion remain little known for the tropical species L. 

 sinuensis. Objectives of the present study were to 

 analyze the periodicity and frequency of reproduc- 

 tive activity, to determine rates of growth in mor- 

 phological features, and to define allometric indica- 

 tors of maturation for populations of L. sinuensis. 

 Resulting implications for management of penaeid 

 shrimp ponds are discussed. 



Materials and methods 



All animals were obtained at the Agrosoledad S.A. 

 shrimp farm on the upper Cispata estuary of the Rio 

 Sinii, Departamento de Cordoba, Colombia, near 

 9°17'N, 75°50'W. In order to avoid overt effects of pond 

 harvesting, feeding, and other management activ- 

 ity, collections were restricted to bottom sediments 

 of earthen drainage canals that extend for several 

 kilometers through the farm. Specimens were indi- 

 vidually extracted from burrows with yabby pumps 

 (Manning, 1975), and samples included all animals 

 retained when extracted sediments were washed on 

 coarse (5-mm) sieves. All population samples were 

 taken within 500 m of the upper end (origin) of the 

 drainage canal system where colonized bottom muds 

 ranged from about 3 to 6 m in width and population 

 density ranged from 15 to 40 animals per m-. 



Monthly sampling of populations extended over 

 four years from December 1991 through December 

 1995. Each monthly sample consisted of animals 

 obtained from burrow openings encountered at ran- 

 dom during walks along transects that crossed ex- 

 posed mudflats at the sampling site during a period 

 of reduced pond discharge. The sample consisted of 

 at least 60 animals, and over 3200 animals were col- 

 lected in the course of the study. Following collec- 

 tion, animals were transported in individual perfo- 

 rated vials (Felder, 1978) to the farm laboratory for 

 morphological analysis. Specimens lacking chelipeds. 



having incompletely regenerated chelae, or with 

 other obvious appendage deformities were excluded 

 from the analyses that involved measures of those 

 appendages but included in analyses of population 

 size-class structure. In the laboratory, each individual 

 was sexed on the basis of anterior pleopod morpho- 

 logical features and evidence of ovaries visible 

 through the integument. Wet weight (WW) was de- 

 termined to ±0.1 g on a top-loading balance after 

 animals were blotted with tissue paper. Dry weight 

 was estimated by drying the animals at 60°C for 48 

 h, and ash content was estimated from weight after 

 ignition at 500"C for 6 h. When present, eggs on pleo- 

 pods were included in weights of ovigerous females. 



Morphometric measurements (Felder and Lovett, 

 1989) were made with dial calipers to ±0.05 mm. 

 Because carapace length (CD is usually less depen- 

 dent on gonadal development than are most other 

 size measurements (Hartnoll, 1982; Felder and 

 Lovett, 1989), it was selected to represent body size 

 and measured from the tip of the rostrum to the pos- 

 terior margin of the cardiac region. Total length (TL) 

 was measured from the tip of the rostrum to the pos- 

 terior margin of the extended telson. Major chela 

 height ( ChH ) was measured as the maximum height 

 of the propodus, inferior margin to superior margin. 

 Major chela width (ChW) was measured as the maxi- 

 mum width of the propodus from the most convex 

 area on the internal surface to the opposite convex 

 area on the external surface. Major chela length 

 (ChL) was measured as the maximum length from 

 the superior proximal articulation of the propodus 

 with the carpus to the superior distal articulation 

 with the dactylus. Between November 1992 and De- 

 cember 1995, ovarian width (OW) of females (the 

 width of the right ovary visible dorsally through the 

 integument of the third abdominal segment) was 

 determined. An index of relative ovarian development 

 was estimated from the ratio OW/CL. Color and num- 

 ber of eggs, color of the ovaries, evidence of para- 

 sites, and occurrence of damaged or missing chelae 

 were also recorded. Egg size was measured under a 

 light microscope and ocular micrometer. Volume of 

 the eggs was calculated from the mean of the long 

 and short axes used as the single diameter measure- 

 ment for a sphere (McEdward and Chia, 1991). 



Temperature and salinity were measured twice 

 daily (dawn and dusk) at the surface and bottom of 

 filled ponds. Temperature was measured ±1 °C with 

 the probe of a YSI® model 57 temperature-compen- 

 sated oxygen meter. Salinity ± 1 ppt was measured 

 with a temperature-compensated refractometer. 



All means were reported along with the 95% CI 

 (confidence interval). Monthly population samples 

 were pooled to compare quarterly variations in the 



