Abstract

Characteristically a nursery habitat for common reef fish, Placencia Lagoon is a relatively large (30 km2) microtidal ecosystem, with an average depth of 1.5 m. Using stratified random sampling to characterize environmental conditions, we collected juvenile and adult fishes and macroinvertebrates with a 1-m beam trawl (5 mm mesh). Among three reaches of the lagoon (upper, lower, middle), a series of three short tows (1 minute) parallel to the shoreline allowed us to minimize within-sample heterogeneity and net clogging. Salinity, temperature, dissolved oxygen, minimum and maximum depths, turbidity, and distance from shore were measured at each site. The bottom was viewed by underwater video to characterize dominant and subdominant surficial substrate and submerged aquatic vegetation (SAV) cover. Salinity and turbidity differed in the lower (14.7 ppt, 95.0 cm Secchi), middle (7.1 ppt, 49.7 cm), and upper (6.8 ppt, 77.0 cm) reaches. The lower reach had a well mixed cover of sea grasses and algae, the middle reach had sparse cover on soft substrates, and the upper reach had various algae cover. Between 22 and 31 July 2006, we collected 2,500+ specimens, mostly juveniles. Numerically, the ten most common taxa were penaeid shrimp (1020), mojarras (451), callinectid crabs (265), flatfishes (166), other decapods (141), gobies (69), snappers (40), grunts (37), sparids (19), and sciaenids (17). The lutjanids included Lane Lutjanus synagris (14), Gray L. griseus (10), Yellowtail Ocyurus chrysurus (10), Mutton L. analis (4), Dog L. jocu (1), and Silk snappers L. vivanus (1). Several juvenile snappers from the lagoon aggregate as adults to spawn in nearby Marine Protected Areas (MPA). Understanding patterns of resource use and the environmental requirements of estuarine-dependent species is an important step in identifying nursery habitats that connect life cycles of populations in coastal areas including nearby MPAs

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