FISHERY BULLETIN: VOL. 78, NO. 2 



Carr and Adams (1973) is qualitative and based on 

 small numbers offish with no particular attention 

 paid to time, space, or fish size. Carr and Adams 

 provided the best published account of food habits 

 of pinfish, noting distinct ontogenetic patterns in 

 the food habits of pinfish and several other fish 

 species which dwell on seagrass beds near Crystal 

 River, Fla. The general conclusion has been that 

 L. rhomboides is a generalist feeder. Because L. 

 rhomboides is an important mediator of benthic 

 organization, and because the fish is a generalist- 

 type feeder, an investigation was undertaken to 

 test for functional responses of the species to food 

 abundance in the field. Ontogenetic, spatial (local 

 and geographic), and temporal (seasonal) varia- 

 tions in food habits of L. rhomboides were 

 explained on the basis of predator morphology, 

 food abundance, and habitat complexity. 



METHODS 



Based on long-term macrophyte data for the 

 area (Zimmerman and Livingston 1976a, b), four 

 collecting stations were chosen from shallow re- 

 gions offshore from the mouths of the Econfina and 

 Fenholloway Rivers, in Apalachee Bay, Fla. (Fig- 

 ure 1). One station was located 2.0 km seaward 

 from each of the river mouths and a second was 

 located 4.0 km seaward. Each site was identified 

 with a permanent marker in a location which was 

 representative of a broad area. Stations Econfina 

 10 and 12 were macrophyte-dominated habitats 

 (primarily T. testudinum and Syringodium 



filiforme) with mean annual macrophyte bio- 

 masses of 214 and 320 g dry w^/m^. The inner 

 station of the Fenholloway area (station 11) was 

 characterized by low macrophyte densities (9.3 g 

 dry wt/m^) and the outer station (Fenholloway 12) 

 was characterized by macrophyte levels (141 g 

 dry wt/m^) intermediate between those levels 

 found at the Econfina stations and those at the 

 inner Fenholloway station (Livingston^). All sta- 

 tions were polyhaline with salinities ranging from 

 approximately 17 to 34%o. The mean water depth 

 at all stations was between 1.6 and 2.0 m. 



Pinfish were collected with a 5 m otter trawl(1.9 

 cm mesh wing and body, 0.6 cm mesh liner). Seven 

 2-min tows (2-3 kn) were taken at each station on a 

 monthly basis. The trawling method for the study 

 site was examined by Livingston et al.^ All tows 

 were made at midday since previous work ( Kjelson 

 et al. 1975; Peters and Kjelson, 1975; Adams, 

 1976) indicated that pinfish feed primarily during 

 daylight hours. All fishes were preserved in 10% 

 Formalin'*-seawater solution, identified to species, 

 and measured for standard length (SL). 



To estimate abundance of prey items in the field, 

 macrobenthic animals (>0.5 mm) and zoo- 

 plankton were collected on each of the fish collec- 

 tion dates. Macrobenthic prey items were collected 

 with 12 7.6 cm diameter cores and identified to 

 species (Stoner in press). Zooplankton were col- 

 lected with horizontal tows of a 0.5 m simple coni- 

 cal plankton net with 0.202 mm mesh and a T.S.K. 

 flowmeter. A single tow was made at each station, 

 on each sampling date, at a speed of 1.5 kn. Tow 

 time was dependent upon the abundance of plank- 

 ton but ranged from 2 to 10 min. Each plankton 

 sample was subsampled with a Folsom plankton 

 splitter when necessary and a 5 ml Hensen- 

 Stemple pipette. One one-hundredth of each sam- 

 ple was counted. Since the importance of plank- 

 tonic prey items in pinfish food habits was limited 

 to a small part of the population, animals were 

 identified only to major taxonomic group (e.g., 

 calanoid copepod, crab zoea, polychaete larva, etc.) 



Figure l . — Locations of collecting sites for Lagodon rhomboides 

 and food organisms offshore from the Econfina and Fenholloway 

 Rivers in Apalachee Bay, Fla. 



^R. J. Livingston, Associate Professor, Department of Biologi- 

 cal Science, Florida State University, Tallahassee, FL 32306, 

 pers. commun. January 1978. 



^Livingston, R. J., K. L. Heck, Jr., and T. A. Hooks. 

 1972. The ecological impact of pulp ■w\\\ effluent on aquatic 

 flora and fauna of north Florida: Comparison of a polluted drain- 

 age system (Fenholloway) with an unpolluted one (Econ- 

 fina). Unpubl. Rep., 186 p., to the Coastal Coordinating Coun- 

 cil, Florida. 



■• Reference to trade names does not imply endorsement by the 

 National Marine Fisheries Service, NOAA. 



338 



