INFAUNAL MACROINVERTEBRATES OF THE CHARLOTTE HARBOR ESTUARINE SYSTEM AND SURROUNDING INSHORE WATERS, FLORIDA By Ernest D. Estevez U.S. GEOLOGICAL SURVEY Water-Resources Investigations Report 85-4260 Prepared in cooperation with the FLORIDA DEPARTMENT OF ENVIRONMENTAL REGULATION Contract Number: 14-08-0001-A-0160 Name of Contractor: Mote Marine Laboratory Principal Investigator: Ernest D. Estevez Contract Officer's Representative: Benjamin F. McPherson Short Title of Work: Infaunal Macroinvertebrates Effective Date of Contract: September 27, 1983 Contract Expiration Date: August 27, 1984 Amount of Contract: $38,374 Date Report is Submitted: October 22, 1984 The views and conclusions contained in this document are those of the author and should not be interpreted as necessarily representing the official policies, either expressed or implied, of the U.S. Government. Tallahassee, Florida 1986 UNITED STATES DEPARTMENT OF THE INTERIOR DONALD PAUL HODEL, Secretary GEOLOGICAL SURVEY Dallas L. Peck, Director For additional information Copies of this report can be write to: purchased from: District Chief U.S. Geological Survey U.S. Geological Survey Books and Open-File Reports Section Suite 3015 Federal Center, Bldg. 41 227 North Bronough Street Box 25425 Tallahassee, Florida 32301 Denver, Colorado 80225 (Telephone: (303) 236-7476) CONTENTS Page MM » » » » . » » » » » > » » » » ^MMBH»MM»^MBH»BH»W**». » » H»M^*»^^^M^*»*»^MM»«»*»^^MM»«» > «» » » J.1 1: llirpO SG dTlCl S COpc ~^«~«~ ^» ^«~~ « «~ ~«~«~«~ «~«~ ^ «~ «~~^ «~~ «~«~«~^ «~~~ -- - - » ^ AC fCTlO oQ^ft/4TT uuuy Regional physiography 3 P 1 -I mo f- ^a w J- -L Uld L. C Shoreline and subtidal environment 8 COcUXlUcIlLo 0/4 -ttnonl* c -. __ __-_ -._ ___________________________________ _ _ ____-. _____ _ _ ^1 ^9 Previous studies of benthic fauna 13 Methods of investigation 13 Hydrography 1 6 r 311 US - **^«- - « " " ^^~^^^^ ^^^~^ ^~«^ ^ ^^^^^ .-.-.« . .-.-. j^ fj »~»«"^_.«_ _«.«_«_«. « « _«.^«_« «M_^«.^«.«_«_«.«.^« « _« « «M_ «M_ « _« _«.._ « « _«_« « _«.«._«_«__«« « « ^ «._«_« « «.«_«_«. «.«_!_ «.^^..^ j^1 ^f\ i^^«.*» i^^«.«.i»^ i^^«.*»^«.«.^^ ^ i^«. ^ ^ JL17 / . .^«« .^ ..................... __ ......«.««..-....«««« __---- ._«« ^ ...... _ «. A1 7/ Hydrography 1 7 MMM«»*>___*>_^BH»«»B>»^*>_^M<».B>»*>_^M<»*>_^^^M<»^*>_^^M<>_*>_^^^BH»^*>_^*>_M X*Uf T\ Benthic macroinvertebrate density -- 26 Equi t ab i 1 i ty 2 7 Common species ; 30 Dominant species ----- - - - - ------- ----- jj^ Species groups between phyla 31 Species groups within phyla 32 XxT) Xo-i o wUO/ > 1 1 a Oo XWL1 { «~>it _________________________________ ________________________ __ J"50 Z. ,,x: \J X. " * * * " " * " " "* »* " " " "* * * " "* »* " " " "* » » " " " » « * « * « « - « - «- « « « * * « -- « -- « « j u Seasonal and aperiodic changes in the fauna 37 Spatial patterns in the fauna 38 Summary and conclusions 41 Selected references 42 Supplementary data I. Sediment formulae and statistics 45 Supplementary data II. Hydrographic characteristics 48 Supplementary data III. Station reports of species ranked by density and percent total station density 51 III ILLUSTRATIONS Page Figures 1-2. Maps showing: 1. Charlotte Harbor estuarine system, southwest Florida 4 2. Drainage basins of the Myakka, Peace, and Caloosahatchee Rivers in Florida 5 3-4. Graphs showing: 3. Frequency distribution of river discharges to the study area 7 4. Seven-day average discharge of the Peace River at Arcadia, January through March 1981, and the 1980 water year (shaded) 9 5-12. Maps showing: 5. Bathymetry and location of sampling stations 11 6. Bottom salinity and dissolved oxygen, September 1980 19 7. Faunal density and equitability (J T ) in May and June 1980 28 8. Faunal density and equitability (J T ) in September 1980 29 9. Similarity of molluscan assemblages (Czekanowski's index) , in September 1980 33 10. Similarity of polychaete assemblages (Czekanowski's index) , in September 1980 34 11. Similarity of crustacean assemblages (Czekanowski's index), in September 1980 35 12. Hydrographic and infaunal subsystems of the Charlotte Harbor estuarine system 39 TABLES Page Table 1. Discharge of the Myakka, Peace, and Caloosahatchee Rivers for water year 1980 8 2. Location and description of sampling stations 14 3. Summary of water-quality data 18 4. Master list of species 20 5. Summary of faunal data by station 27 6. Frequency distribution of species commonality 30 7. Geographic subsystems of the study area 38 IV INFAUNAL MACROINVERTEBRATES OF THE CHARLOTTE HARBOR ESTUARINE SYSTEM AND SURROUNDING INSHORE WATERS, FLORIDA By Ernest D. Estevez ABSTRACT The Charlotte Harbor estuarine system is situated between the mouths of the Myakka, Peace, and Caloosahatchee Rivers and coastal barrier islands. Most of the area is shallow (less than 2 meters) and the predominant benthic environment is sandy and unvegetated. A total of 25 intertidal and subtidal stations were sampled during two seasons (May-June and September) in 1980 for benthic infauna, sediment, and hydrographic parameters. Nearly all the 48,513 specimens other than nemerteans, nematodes, and oligochaetes were identified to species. Bottom sediments were similar throughout the area, except at inlets where they were coarser and at upper river stations where they were more organic. Bottom salinity and dissolved oxygen increased along a gradient toward the south and west, especially in September. Species number increased along the same gradient, but densities were highest at river mouths and Pine Island Sound (May-June) or in coastal Charlotte Harbor (September). The middle harbor is a transitional area along the gradient. It is affected by stratifi­ cation and near-anoxic bottom conditions. Six subsystems had characteristic hydrographic and faunal features that portray the system as an integrated, rather than sharply subdivided, environment. Seasonal trends within and among subsystems were evident, but not extreme, due to relatively dry conditions in 1980. INTRODUCTION Estuaries are complex transitional ecosystems between oceanic and riverine environments, noted for their high productivity of sport and commer­ cial fisheries. In addition, estuaries provide a unique and essential habitat for a wide range of plants and animals. Estuaries of the Florida west coast are facing increased development pressure and have become the center of several resource management controversies. Data needed for effective resource management are lacking for many Florida estuaries. The Charlotte Harbor estuarine system is facing potential environmental problems because of projected large population growth in its basin. The Governor of Florida established a committee composed of local, regional, and State agencies to recommend the course of action that Florida should take in planning for this growth. The committee, through its Technical Advisory Committee (TAG), asked the U.S. Geological Survey to prepare a proposal and a plan of study for a comprehensive environmental assessment of the area. The Survey, in cooperation with the TAG, prepared the proposal in 1980 and the plan of study in 1981. Based on these documents and subsequent meetings, the Survey began a multidiscipline, 7-year study of the basin and estuarine system in 1982. Purpose and Scope The overall objective of the Survey study is to describe existing conditions and evaluate the impact of future development on water-related resources of the estuarine system. Central to the objective is the relation between hydrodynamics and water quality. This report addresses one aspect of the study objective to evaluate the macroinvertebrate infauna of soft bottom environments of Charlotte Harbor and surrounding inshore waters. The report describes the sampling approach and results from a reconnaissance of macro- invertebrate infauna performed in 1980 by the Mote Marine Laboratory (MML). This compilation and analysis was undertaken by MML in cooperation with the U.S. Geological Survey and the Florida Department of Environmental Regulation. Specific objectives of the reconnaissance and report were: 1. To provide a listing of infaunal macroinvertebrates from soft bottom environments; 2. To assess the suitability of infaunal macroinvertebrate sampling methods; 3. To identify spatial and seasonal trends or patterns in benthic communi- tites and, where possible, relate these patterns to tidal locations, salinity, sediment type, and other environmental parameters. The 1980 benthic project was limited to the infauna of unvegetated soft bottoms (for example oyster reefs and seagrass beds were not sampled). Acknowledgments The science of benthic community ecology involves numerous persons in collection, sorting, taxonomy, and data processing. The author takes respon­ sibility for design and interpretation of this study but gratefully extends credit to these individuals who made it possible. Sample collection: K. Caraccia, J. Enrico, P. Hull, L. McCann, T. Russell, R. Tegencamp, R. Yarbrough; Sorting: G. Blanchard, R. Buhler, K. Burns, I. Dodson, E. Kinney, D. McCallum, J. Valentine, S. Wilkinson; Taxonomy and sediments: J. Culter, D. Devlin, J. Leverone, R. Lee, N. Maddox, J. Mapes, M. Milligan, K. Molar; Data and text processing: G. Blanchard, L. DeAnna, B. Fortune, L. Franklin, L. Fraser, B. Hussey, D. Latulippe, M. Spring. Benjamin F. McPherson of the U.S. Geological Survey is acknowledged for his assistance during report preparation. K. Mahadevan and G. Blanchard made useful criticisms of early drafts. The 1980 sampling trips were sponsored by Mote Marine Laboratory. Study Area