TP 76-20 Lethal Effects of Suspended Sediments on Estuarine Fish by J.M. O'Connor, D.A. Neumann, and J.A. Sherk, Jr. TECHNICAL PAPER NO. 76-20 DECEMBER 1976 | \ DOCUMENT | i COLLECTION / 4 — Approved for public release; distribution unlimited. Prepared for U.S. ARMY, CORPS OF ENGINEERS COASTAL ENGINEERING RESEARCH CENTER EB Kingman Building Y5O Fort Belvoir, Va. 22060 Cine: ; a Te | FISK CAL VE is Reprint or republication of any of this material shall give appropriate credit to the U.S. Army Coastal Engineering Research Center. Limited free distribution within the United States of single copies of this publication has been made by this Center. Additional copies are available from: National Technical Information Service ATTN: Operations Division 5285 Port Royal Road Springfield, Virginia 22151 Contents of this report are not to be used for advertising, publication, or promotional purposes. Citation of trade names does not constitute an official endorsement or approval of the use of such commercial products. The findings in this report are not to be construed as an official Department of the Army position unless so designated by other authorized documents. MUNA TL 0 0301 008955? 1 UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGE (When Data Entered) REPORT DOCUMENTATION PAGE 1. REPORT NUMBER 2. GOVT ACCESSION NO.) 3. RECIPIENT’S CATALOG NUMBER TP 76-20 4. TITLE (and Subtitle) 5. TYPE OF REPORT & PERIOD COVERED LETHAL EFFECTS OF SUSPENDED SEDIMENTS ON ESTUARINE FISH Technical Paper 6. PERFORMING ORG. REPORT NUMBER 8. CONTRACT OR GRANT NUMBER(S, - AUTHOR(s) J.M. O'Connor D.A. Neumann J.A. Sherk, Jr. - PERFORMING ORGANIZATION NAME AND ADDRESS DACW72-71-C-0003 10. PROGRAM ELEMENT, PROJECT, TASK AREA & WORK UNIT NUMBERS Natural Resources Institute University of Maryland e Park, Maryland 20742 - CONTROLLING OFFICE NAME AND ADDRESS Department of the Army V04230 12. REPORT DATE December 1976 15. SECURITY CLASS. (of this report) UNCLASSIFIED 15a, DECL ASSIFICATION/ DOWNGRADING SCHEDULE DISTRIBUTION STATEMENT (of this Report) Approved for public release; distribution unlimited. . DISTRIBUTION STATEMENT (of the abstract entered in Block 20, if different from Report) - SUPPLEMENTARY NOTES - KEY WORDS (Continue on reverse side if necessary and identify by block number) Estuarine fish Mineral solids Natural sediments Patuxent River, Maryland Lethal effects Suspended solids ABSTRACT (Continue on reverse side if necesaary and identify by block number) A 3-year laboratory study identified certain estuarine fish sensitive to the effects of particle size and concentration of (a) suspended mineral solids similar in size to sediments likely to be found in estuarine systems in concentrations typically found during flooding, dredging, and disposal of dredged material, and (b) natural sediments in identical experiments. Significant mortality of estuarine fish was demonstrated at these suspended mineral solid concentrations. Estuarine fish were classified, using static Continued DD , FORM 1473 EDITION OF T NOV 65 IS OBSOLETE Heat) UNCLASSIFIED ee SECURITY CLASSIFICATION OF THIS PAGE (When Data Entered) UNCLASSIFIED SECURITY CLASSIFICATION OF THIS PAGE(When Data Entered) bioassays as: Tolerant (24-hour LCj9 > 10 grams per liter), sensitive (10 grams per liter > 24-hour LCj9 > 1.0 gram per liter), or highly sensitive (24-hour LC, 9 < 1.0 gram per liter) to fuller's earth suspen- sions. Generally, bottom-dwelling fish species were most tolerant to sus- pended solids; filter feeders were most sensitive. Early life stages were more sensitive to suspended solids than adults; filter feeders were most sensitive. Bioassays with natural sediments indicated that suspen- sions of natural muds affected fish in the same way as fuller's earth, but higher concentrations of natural material were required to produce the same level of response. The effect of finely divided solids on fish was dependent on concen- tration, particle-size distribution, and angularity of the suspended particles. The cause of death was the same in all experiments--anoxia. This study provides base-line information for preproject decision- making based upon the anticipated concentration of suspended sediments at the project site and the effect of various lengths of exposure on estuarine fish of different life-history stages and habitat preference. / 2 SECURITY CLASSIFICATION OF THIS PAGE(When Data Entered) UNCLASSIFIED PREFACE This report is published to provide coastal engineers with informa- tion on the lethal effects of suspended sediments on estuarine organisms. The work reported is a part of a continuing program of research on the ecological effects of coastal engineering activities. The report pre- sents the results of part of a 3-year laboratory study on the subject. The work was carried out under a contract originating in the Office, Chief of Engineers, which was monitored under the coastal ecology research program of the U.S. Army Coastal Engineering Research Center (CERC). The original contract report (CERC Contract No. DACW72-71-C-0003) was prepared by Dr. J.M. O'Connor, Mr. D.A. Neumann, and Dr. J.A. Sherk, Jr., while on the staff of the Natural Resources Institute, University of Maryland, College Park, Maryland. Mr. A.K. Hurme, CERC, technically reviewed, condensed, and revised that part of the original report pertaining to the lethal effects of suspended solids on estuarine fish. Mr. Robert M. Yancey, Chief, Ecology Branch, was CERC contract monitor for the report, under the general supervision of Mr. R.P. Savage, Chief, Research Division. Comments on this publication are invited. Approved for publication in accordance with Public Law 166, 79th Congress, approved 31 July 1945, as supplemented by Public Law 172, 88th Congress, approved 7 November 1963. JOHN H. COUSINS Colonel, Corps of Engineers Commander and Director CONTENTS CONVERSION FACTORS, U.S. CUSTOMARY TO METRIC (STI) I INTRODUCTION. II MATERIALS AND METHODS 1. General 2. Bioassays Ustine Namera Solvds! og 3. Bioassays Using Resuspended Natural Sediments iii! RESULTS: 1. Bioassays letiac Mimerenl Soltds: 49 ¥6 2. Bioassays Using Resuspended Natural Sediments IV. DISCUSSION. V CLASSIFICATIONS . VI SUMMARY AND CONCLUSIONS . LITERATURE CITED. APPENDIX - Analyses of Sediments. TABLES MES SSPECUESM ae |n sess eeee ie: fe Lowest fuller's earth concentration causing 100-percent mortality in a 24-hour exposure for five estuarine fish LCj9, LCsg, and LCog values determined for 24-hour exposure Of estuarine fushi 6! 0 Sui sth) ob ict On aes LCj}9, LCs5g, and LCgg values for white perch and spot, with increasing duration of exposure to fuller's earth Comparison of 24-hour LC values of fuller's earth and natural Patuxent River, Maryland, sediments FIGURES Twenty-four-hour concentration-mortality curves for six species of estuarine fish exposed to fuller's earth . Effect of fuller's earth on white perch, LCgg, LCsqg, and LC). Effect of fuller's earth on spot, LCog, LCs59, and LCj9 Concentration mortality curves for white perch exposed to suspensions of fuller's earth for 12, 20, 24, and 48 hours. Concentrations mortality curves for spot exposed to suspensions of fuller's earth for 12, 18, 24, and 48 hours. LCj9 and LCsg values for white perch at 12-, 20-, 24-, and 48-hour exposures to suspensions of fuller's earth. LCjg and LCsg values for spot at 12-, 18-, 24-, and 48-hour exposures to suspensions of fuller's earth. 13 12 14 15 16 17 21 22 CONVERSION FACTORS, U.S. CUSTOMARY TO METRIC (SI) UNITS OF MEASUREMENT U.S. customary units of measurement used in this report can be converted to metric (SI) units as follows: Multiply by To obtain inches 25.4 millimeters 2.54 centimeters square inches 6.452 square centimeters cubic inches 16.39 cubic centimeters feet 30.48 centimeters 0.3048 meters square feet 0.0929 square meters cubic feet 0.0283 cubic meters yards 0.9144. meters square yards 0.836 square meters cubic yards 0.7646 cubic meters miles 1.6093 kilometers square miles 259.0 hectares acres 0.4047 hectares foot-pounds 1.3558 newton meters ounces 28.35 grams pounds 453.6 grams 0.4536 kilograms ton, long 1.0160 metric tons ton, short 0.9072 metric tons degrees (angle) 0.1745 radians Fahrenheit degrees 5/9 Celsius degrees or Kelvins! ‘To obtain Celsius (C) temperature readings from Fahrenheit (F) readings, use formula: C = (5/9) (F — 32). To obtain Kelvin (K) readings, use formula: K = (5/9) (F — 32) + 273.15. wats supe, AENEY aT Ge Si ee eRe AE bd S r Ps ety if Pane Sate tral i Phe Mi e P Per \( ea mens en's wea ne aude NOR vu vit ina oe gohan y i iat us: Fi 7 ri vives ea LEY rrr ied i ar Pei} LETHAL EFFECTS OF SUSPENDED SEDIMENTS ON ESTUARINE FISH by J.M. O'Connor, D.A. Newnann, and J.A. Sherk, Jr. I. INTRODUCTION Previous reports on the lethal effects of suspended particulate matter on estuarine fish have dealt with fine particles of commerical prepara- tions such as kaolinite or fuller's earth (Rogers, 1969; Sherk and O'Connor, 1971; Sherk, O'Connor, and Neumann, 1972; Sherk, O'Connor, and Neumann, 1976), or with suspensions of fine particles of varied and undetermined compositions such as incinerator fly ash (Rogers, 1969). Studies of the effects of natural suspended solids on fish usually were concerned with growth, yield, or abundance-diversity determinations in natural communities (Ellis, 1936, 1937; Stickney, 1972; European Inland Fisheries Advisory Commission, 1964). The primary objective of this study was to differentiate the effects of suspended natural sediments from the effects of suspended mineral parti- cles on estuarine fish. The results of bioassay tests conducted with five species of estuarine fish exposed to suspensions of fuller's earth and resuspended natural sediments are presented (see also Sherk and O'Connor, 1971; Sherk, O'Connor, and Neumann, 1972; Sherk, O'Connor, and Neumann, 1976). The fish species tested in suspensions of mineral solids and natural sediments were: White perch (Morone americana), spot (Letostomus sxanthurus), menhaden (Brevoortia tyrannus), striped killifish (Fundulus majalts), and mummichog (F. heteroclitus). Represented within this group are the common littoral or shallow-water estuarine fish (striped killifish and mummichog), filter-feeding fish which use the estuary primarily as a nursery ground (menhaden), and two pelagic (open water) fish (white perch and spot). Fish in this range of diverse habitats and feeding habits were chosen to provide (a) an estimate of the range of tolerance among different estuarine fish exposed to highly turbid waters, and (b) the differing effects of fine commercial, industrial, or natural particles on typical estuarine fish. II. MATERIALS AND METHODS 1. General. The lethal effects of suspended solids on fish were determined by static bioassay test procedures. Test groups were simultaneously exposed to four different concentrations of suspended solids and one group was a control (no added suspended solids). Particle concentration varied, depending upon the species tested and the duration of the test (12, 18, 20, 24, and 48 hours). Sediment was maintained in suspension during the test period by con- tinuous agitation with a submersible pump and aeration by injection of compressed air. The control tank received the same pumping and aeration treatment. Fuller's earth (Fisher F-90, technical grade), kaolinite (Hydrite-10, Georgia Kaolin Company, Elizabeth, New Jersey), and resuspended bottom sediments from the upper Patuxent River estuary were used in the bioassay experiments. Concentrations in the experimental tanks were determined by weight. Replicate 5-milliliter samples were drawn from test and control tanks and dried. The difference between the weight of the dried control sample and the dried test tank sample represented the added sediment load in grams per liter (g ie Fish were exposed to suspended solids in 27-liter polyethylene tanks. Temperatures were maintained within +1.5° Celsius by immersing the test tanks in a circulating water bath. Tanks were monitored for fish mortality, temperature, pH, and dissolved oxygen. Lethal concentrations (LC) of suspended solids causing 10-, 50-, and 90-percent mortality of test fish were determined by normit analysis (personal communication, McErlean, Environmental Protection Agency, 1969), a modification of probit analysis (Berkson, 1953). 2. Bioassays Using Mineral Solids. Tests using commercial preparations of the mineral solids, kaolinite and fuller's earth, were conducted using 14 fish species from two locations (Table 1). Six species were from Delaware Bay (bay anchovy, Anchoa mitehtlit; Atlantic silverside, Menitdta menidta; croaker, Mtcropogon undulatus; weakfish, Cynoscton regalis; bluefish, Pomatomus saltatrix; and cusk eel, Rissola marginata). Eight species were from the Patuxent River estuary, Maryland (spot; toadfish, Opsanus tau; mummichog; hogchoker, Trinectes maculatus; menhaden; white perch; striped bass, Morone saxattlis; and striped killifish). Bioassay tests for the Delaware Bay fish were conducted at the University of Delaware Bayside Laboratory, Lewes, Delaware; tests for the Patuxent River estuary fish were conducted at the University of Maryland Hallowing Point Field Station, Prince Frederick, Maryland. Fish were collected by otter trawl or haul seine and transported in water to holding facilities. Bayside Laboratory holding facilities con- sisted of 140-liter polyethylene tanks immersed in temperature-controlled water baths. Water quality at Bayside was maintained by a combination of aeration and filtration in a closed-system recirculating unit. Hallowing Point holding facilities consisted of 250-liter polyethylene tanks immersed in temperature-controlled water baths. An inline protein skimmer device was used to maintain water quality in the closed system. All fish were starved for 2 to 5 days before testing. Hydrite-10 and fuller's earth were analyzed for particle size, organic content, and Table 1. Test species. Capture location? Species Scientific name Common name Capture method? Menhaden Brevoortta tyrannus H.S. Anchoa mitehillt Bay anchovy H.S. Fundulus majalis Striped killifish H.S. F. heteroclitus Mummichog H.S. Rissola marginata Cusk eel H.S. Mentdia menidta Atlantic silverside H.S. Morone saxatilis Striped bass O.T. Morone americana White perch O.T. Letostomus xanthurus Spot 0.T. Micropogon undulatus Croaker 0.T. Cynoscion regalis Weakfish H.S. Trinectes maculatus Hogchoker O.T. Pomatomus saltatriz Bluefish H.S. GRID ESS Oystenitoade ish. wie lfrom American Fisheries Society Special Publication No. 6. 2Del., University of Delaware Bayside Laboratory, Lewes, Delaware. P.R., Patuxent River estuary, Maryland. 3H.S., 15.24-meter beach seine. 0.T., 6.096-meter otter trawl pulled at 3 knots for 3 to 5 minutes, acid-extractable cations (see App.). Since water temperature and salinity at the Bayside Laboratory fluctuated with tides, the fish were tested at a median temperature of 22° + 2° Celsius and at the same salinity as that at the time and place of capture. Salinity range during testing was 18 to 30 parts per thousand (9/00). The fish at Hallowing Point were captured in water of 4 to 6 °/oo salinity over a temperature range of 15° to 27° Celsius. Tests were con- ducted at approximately 5.5 °/oo salinity and at 25° + 2° Celsius. 3. Bioassays Using Resuspended Natural Sediments. All natural sediment bioassay tests were made at Hallowing Point. Sediment was obtained in 6.1 meters of water near Long Point in the Patuxent River estuary. Several samples were obtained at one time and were mixed before use. Although the same batch of sediment was not used in all tests, results using different sediment batches were repeatable. Natural sediments were kept in polyethylene containers and were covered with saline water (4 to 6 °/oo). Natural sediments were added to test tanks as a mud-water slurry. Test tanks were partially filled with the slurry, and the concentration of solids was determined. The slurry was then diluted with filtered river water to obtain the desired test concentration. Til. RESULTS 1. Bioassays Using Mineral Solids. Eleven of the 14 species used in this study were exposed to suspen- sions of kaolinite (Hydrite-10). All fish exposed to kaolinite survived 24-hour exposure in concentrations as high as 140 g 1-1. Several species (white perch, spot, toadfish, mummichog, hogchoker, and menhaden) were exposed to 140 g 17! kaolinite for 48 hours with the same result; no deaths were directly attributable to the mineral. Usually, the fish became highly active for a short time when placed in kaolinite suspensions. Activity returned to normal after 0.5 to 2 hours. Three species (bluefish, cusk eel, and bay anchovy) were not exposed to kaolinite because too few individuals were collected. Survival of the 14 species was assessed in suspensions of fuller's earth. Three species (toadfish, cusk eel, and hogchoker) showed no mortality attributable to the effects of fuller's earth after 24-hour exposure to concentrations of 96 to 140 g 171. The response of 5 of the 11 species killed in the fuller's earth suspension (striped bass, croaker, weakfish, bluefish, and menhaden) was not consistent enough to calculate accurate LC values. The tolerance of these fish, as the lowest concentration at which 100-percent mortality occurred, is presented in Table 2. Exposure of the remaining six species (Atlantic silverside, striped killifish, white perch, bay anchovy, spot, and mummichog) to fuller's earth resulted in consistent concentration mortality responses. From these responses, calculations of lethal concentrations for 10-, 50-, and 90-percent mortality in 24-hour bioassays were made. Consistent concen- tration mortality responses of white perch were observed for 12-, 18-, and 24-hour exposures. Spot showed consistent responses for the 12-, 20-, and 48-hour exposures. The six species varied widely in sensitivity to suspensions of fuller's earth, as indicated by 24-hour lethal concentration (Table 3) and concentration-dependent response curves (Fig. 1). The LCs5g response range was 36.60 g 1~! and varied from 2.40 g 17! (Atlantic silverside) to 39.00 g 17! (mummichog). LCgg values for 24-hour assays had a range of 56.57 g 1-1, from 9.60 g 17! (bay anchovy) to 62.17 g 17! (mummichog). The total range of LCj9 values was 23.90 g 1-1, from 0.57 g 17! (Atlantic silverside) to 24.47 g 171 (mummichog). The concentration range from LCjg to LCgg within each species varied widely. The species with the highest LC5q value (mummichog) showed a range of 37.70 g 17! between LCj9 and LCgq (Table 3). The species with the lowest LCs5g value (Atlantic silverside) showed a range of 9.43 g yo between LCjg and LCog. Species with intermediate 24-hour LCsa values (white perch and spot) showed ranges of 28.76 and 18.54 g 1™°, respectively, 10 Table 2. Lowest fuller's earth concentration causing 100-percent mortality in a 24-hour exposure for five estuarine fish. Test conditions Salinity Temperature (°/00) (°C) Individuals Species Age class Concentration g 17! fuller’ s earth Menhaden Menhaden Bluefish Weak fish Weakfish Striped Bass Croaker Table 3. LCy9, LCsq, and LCog values determined for 24-hour exposure of estuarine fish. Species Lethal concentration (g 17! fuller's earth) White perch Spot 1.500 Bay anchovy 0.982 Atlantic silverside 1.000 Mummi chog 1.794 Striped killifish \correlation Coserieienes (r) and Eeeeiienes of aS (r2) aatived from regres- sion analyses are presented as statistical estimates of the decimal fraction of mortality accounted for by concentration effects. Pct Killed in 24 Hours Evoune sly. Atlantic Silverside Bay Anchovy White Perch Spot Striped Killifish Mummichog Log Concentration of Fuller's Earth (g 2) Twenty-four-hour concentration-mortality curves for six species of estuarine fish exposed to fuller's earth. between LC,, and LCgg. The range of concentration between LC)q and LCqo did not necessarily reflect the sensitivity of the species as indicated by the 24-hour LCso Values For example, the LC,g to LCgg range for white perch was 28.76 g 171; spot, with a 24-hour LCsq more than twice that of white perch (20. 34 versus 9.85 g 171) had an LCjg to reoe range of only 18.54 g 1” 1, Similarly, Wey anchovies (LC59 = 4.71 g 1°~) had an LCj9 to LCgg range of 7.29 g 1-1; the more sensitive Atlantic silverside Ween) 2240) g le) had ani LGig to) LGqg range of 9.43 9 1e.. White perch and spot exposed to fuller's earth for varying times showed an overall reduction of LCj9, LCs59, and LCg9, with increasing dura- tion of exposure (Table 4). These values were plotted logarithmically and are presented as toxicity curves (Figs. 2 and 3) (Sprague, 1969) and as concentration mortality curves (Figs. 4 and 5). Table 4. LCj,9, LCs5q, and LCgg values for white perch and spot, with increasing duration of exposure to fuller's earth. Duration of bioassay ¢h) INot tested. 2. Bioassays Using Resuspended Natural Sediments Lethal concentrations of natural sediments during 24-hour exposures were determined for white perch,: spot, menhaden, and striped killifish, and compared with the 24-hour LC values for fuller's earth (Table 5). Table 5. Comparison of 24-hour LC values of fuller's earth and natural Patuxent River, Maryland, sediments. Sediment Species LCj9 | Natural Sie Fuller's earth BSH I LC59 Natural 128.2 Fuller's earth 38.18 LCo9 | Natural 169.3 Fuller's earth 3 Duration of Expos Figure 2. | 2 Sy GY 6) 10 20 30 40 50 60 Concentration (gf) of Fuller's Earth in Suspension Effect of fuller's earth on white perch, LCo99 (solid points), LCs5q (open points), and LCjg (x). Dotted line indicates 48-hour exposure, the maximum duration of exposure. Duration of Exposure (h) Figure 3. 2 3 4 5 10 20 30 40 60 Concentration (g 2.) of Fullers Earth in Suspension Effect of fuller's earth on spot, LCgqg (solid points), LCso (open points), and LCj9 (x). Dotted line indicates 48-hour exposure, the maximum duration of exposure. Log Concentration of Fuller's Earth (g a7') Figure 4. Concentration mortality curves for white perch exposed to suspensions of fuller's earth for 12 hours (1), 20 hours (2), 24 hours (3), and 48 hours (4). 4 3 2\ LC9o9 LCjo Log Concentration of Fuller's Eorth (gg') Figure 5. Concentration mortality curves for spot exposed to suspen- sions of fuller's earth for 12 hours (1), 18 hours (2), 24 hours (3), and 48 hours (4). The LC5qg value for white perch exposed to resuspended natural sediments was 19.80 g 171; the LCsg value for fuller's earth was 9.85 g Weep A similar range applied to LCqg and LC,q values in resuspended natural sedi- ments when compared with fuller's earth, and varied between 39.40 versus 31.81 g 1°} (LCg9) and 9.97 versus 3.05 g 171 (1C)9), respectively. Spot exposed to natural sediments had a LCsg value of 88.00 g 12 and LCjg and LCg9q values of 68.75 and 112.63 g 1-1, respectively, for a 24-hour exposure. These values contrast with 24-hour values of fuller's Earth) at 13.81) 20.354, and 3362) for LCi/o,) LCc og, eandylGog.. hespectavelye Spot were previously reported to have a relatively low tolerance to resus- pended natural sediment (48-hour LCs5q = approximately 3 g 172) (Sherk, O'Connor, and Neumann, 1972). Lethal concentrations for replicated 48- hour exposures were essentially equal to 24-hour values. This suggests that (a) spot have a compensatory mechanism that allows them to tolerate high levels of natural suspended material for at least 48 hours, and (b) the preliminary results for this species (Sherk, O'Connor, and Neumann, 1972, p.24) were in error. This error was probably caused by inadequate oxygenation of the experimental sediments. Spot exposed to these suspen- sions of natural material were observed to have a high initial oxygen demand. As a result, high mortality occurring in experimental tanks was probably caused by low oxygen concentration, not by sediment concentra- tions. The alimentary canal of fish from these bioassays was packed with sedi- ment. The entire digestive tract was swollen and distorted by ingested material. Separate concentration-dependent mortality determinations (48 hours, 25° Celsius) were conducted on the common mummichog with both fuller's earth and natural sediment. For fuller's earth suspensions, 48-hour values Were-N i LGg) =) S586) gil eLGny — e45)lGl lo lie andi Co qe—564SOmpas leu Natural sediment concentrations could not be maintained high enough to cause sufficient mortality to determine lethal concentrations. Sixty-two percent of adult mummichogs survived concentrations greater than 125 g 1=4 for 24 hours and 100 percent survived concentrations in excess of 109 g 1! for 72 hours. Striped killifish exposed to resuspended natural sediments for 24 hours had LCi9, LCsq, and LCo9qg values of 97.1, 128.2, and 169.3 g 171, respec- tively. IV. DISCUSSION The effects of suspended natural and mineral sediments on estuarine fish are partially dependent on certain characteristics of the suspended materials. No species, including menhaden, died in suspensions of kaolinite clay (median particle size of 0.55 micrometer). Menhaden are highly sensitive to suspensions of solids other than kaolinite. However, suspensions of fuller's earth in concentrations exceeding 0.65 g 17! were lethal to most species. Physical comparison of the two mineral solids suggests that the differences in the lethal effects of these substances (Table 5) may be due in part to particle-size distribution (see App.). Suspended solid particles of differing composition vary greatly in lethal effect on fish (European Inland Fisheries Advisory Commission, 1964; Rogers, 1969). Using a variety of solids (kaolinite, diatomaceous earth, natural glacial till, and incinerator fly ash), Rogers (1969) concluded that the lethal effect of a suspended solid is dependent on particle shape and angularity rather than on particle size. However, it is not known how particle angularity causes rapid (24 to 96 hours) mortality in test fish. Common symptoms in dead and moribund test fish are extensive hemor- rhaging of minute blood vessels over the entire body surface and packing of the gills with sediment. Microscopic examination of fresh gill prep- arations from recently dead fish showed no hemorrhaging associated with exposure to kaolinite or fuller's earth. Rogers' (1969) hypothesis could not be evaluated because particles of kaolinite and fuller's earth were flat and platelike, and the sand grains in the natural sediments were relatively smooth. Respiration studies show some effects of suspended mineral solids on fish. Rogers (1969) noted increased survival among test fish when he bub- bled air into his test chambers. This suggests that exposure to suspended solids leads to anoxia. The relationship between particle angularity and the lethal effect may result from angular particles having a greater affinity for the gill surface, thus causing anoxia by covering or abrading the respiratory epithelium. Natural sediment suspensions were less harmful than mineral solid suspensions for every species tested (Table 5). The lethal effect of the natural mud probably was due to clogging of the gill interstices, as opposed to the coating effect of fuller's earth particles. Ellis (1937) described several ways in which particles could cause asphyxiation in fish; e.g., coating by fine particles and clogging by larger particles - such as those found in natural mud. Although Ellis' discussion did not include details of fish gill mor- phology, investigations by Muir (1969) and Cameron and Davis (1970) sup- port the hypothesis that suspended particulate matter is lethal to fish at concentrations well in excess of those observed in nature. The lethal effect of finely divided solids on fish depends on several factors although the cause of death is the same--anoxia. Fine particles generally will not eause death unless the particles are angular. Larger particles trapped by the primary and secondary lamellae of the gill block the minute circulation channels between the secondary lamellae. This leads to "dead space" at the primary site of gas exchange; limited oxygen diffusion occurs in these dead spaces. A coating of clay particles over the entire gill surface would be less likely to permit gas exchange. 19 Fish may be able to tolerate greater concentrations of natural sedi- ments than mineral solids because: (a) The abrasive mineral particles are diluted by organic material in the natural sediment and therefore are not as damaging, or (b) the larger natural particles allow water to flow through the larger interstices and reach the gill surface. In freshwater systems, concentrations of 2 to 6 g aD Oe SiLile may persist for 15 to 20 days in flood-stage rivers (European Inland Fisheries Advisory Commission, 1964). Similarly, freshwater streams polluted with china-clay mining waste may carry burdens of 1 to 6 g 17!, continuously (Herbert and Merkins, 1961). Saline waters carry lower concentrations of suspended particles because of flocculation, dilution, and the ''salting- out'' phenomenon. However, Masch and Espey (1967), in a study of shell- dredging operations in Galveston Bay, Texas, recorded suspended solid concentrations of 4.15 g 1~! in the immediate vicinity of a dredge dis- charge. Concentrations were 0.3 g 17! suspended solids 838.2 meters from the discharge. Suspended solid concentrations may reach 1.2 g 171 during flood conditions, such as Hurricane Agnes in 1972, in the upper Patuxent River, Maryland. Values recorded during the summer of 1972 were generally between 0.08 and 0.14 g 17!, depending on local weather conditions and tidal scouring. Suspended solid concentrations capable of causing signi- ficant mortality in certain estuarine fish species at the 10- and 50- percent levels can be maintained in estuarine systems near dredging operations or during times of excessively high runoff. The relationship between suspended solid concentrations and their effect on mortality with increasing exposure time are shown in Table 4. Arithmetic plots (Figs. 6 and 7) of the LCjq and LCs5q data from Table 4 allow an estimation of the severity of the impact of a given concentration of fuller's earth upon white perch and spot. For white perch, the concen- tration of fuller's earth needed to cause 90-percent mortality for a 48- hour exposure (not shown) was 25 percent, by weight, of the 12-hour LCo9g value. However, the LCj}9 value for white perch exposed to fuller's earth for 48 hours was only 2.2 percent of the 12-hour LC,g value. Thus, very low concentrations of suspended solids caused low, yet important levels of mortality during long exposure periods. For white perch (Fig. 6), the LC,}g duration of exposure had its effect primarily on the lower levels of mortality. Thus, using LCj9 data (Fig. 6), it was found that the visual approximation afforded an excellent estimate of inflection between 20 and 24 hours at approximately 4 g 17} fuller's earth. Mortalities beyond the 48-hour LC;g approached zero. Extrapolated LC,}g values for 72- and 96-hour exposures were 0.06 and 0.0045 g 19 respectively, or well within the range of suspended material carried by "undisturbed" natural systems. Fish exposed to concentrations of suspended solids normally found in natural waters are not adversely affected by concentrations below a cer- tain threshold value. The concentration of 0.0045 g 17! is well below 20 48 w $ N (eo) Concentration of Fuller's Earth (g vm) ™M psy (e) l2 24 36 48 60 Exposure Time (h) Figure 6. LCjq and LCsg values for white perch at 12-, 20-, 24-, and 48-hour exposures to suspensions of fuller's earth. 2| Concentration of Fullers Earth (g Z “ty px) oO 48 (4%) fo ib) $ () 0 12 24 36 48 60 Exposure Time (h) Figure 7. LCjg and LCsg values for spot at 12-, 18-, 24-, and 48-hour exposures to suspensions of fuller's earth. 22 that threshold. The concentration threshold for a given species may be determined by the ability of the fish to cleanse the gills by the cough- ing reflex, or by continuous secretion and sloughing of a protective mucus sheet. The LC,9 and LC59 curves (Fig. 7) for spot in suspensions of fuller's earth do not show a marked inflection point. The extrapolated 72- and 96-hour LC,g values for spot (0.135 and 0.017 g 171, respectively) would be within the range of concentrations found in natural waters. White perch were exposed to suspended solids at 0.65 g 1>? for as long as 5 days (O'Connor, Neumann, and Sherk, in preparation, 1976). From an extension of the LCsg and LCjg curves relating exposure duration to concen- tration, concentrations of 0.65 g 1-1 would be expected to cause 10-percent mortality in less than 5 days. A threshold concentration between 0.67 and 0.65 g 17! appears to exist. Higher concentrations may cause death, at least at the 10-percent level, during exposure of 48 hours; lower con- centrations are unlikely to cause death. However, fish exposed to 0.65 g 17! for 5 days showed sublethal physiological changes in blood charac- teristics and damage to gill tissues (O'Connor, Neumann, and Sherk, in preparation, 1976). V. CLASSIFICATIONS Fish species used in these experiments may be placed in the following three groups according to their toleration of suspended solid concentra- tions. Classification is subjective and based on LCjg values of fuller's earth, because 10-percent mortality in addition to natural mortality rates is a more realistic maximum than a 50-percent mortality limit (Ricker, 1954). (a) Class I: Suspension-Tolerant Species. The concentration of fuller's earth required to attain the 24-hour LCjg value is equal to or in excess of 10 g 1~!. Tolerant species were the mummichog, striped killifish, and spot. Toadfish, hogchoker, and cusk eel were tested for suspension. tolerance, but concentration-dependent mortality curves were not determined. The tolerant species commonly inhabit the mud-water interface where suspended solid concentrations are high (Masch and Epsey, 1969); e.g., the killi- fish, hogchoker, and cusk eel frequently burrow into the bottom and remain covered for extended periods of time (Hildebrand and Schroeder, 1928). The toadfish is a relatively inactive bottom dweller (Hildebrand and Schroeder, 1928). (b) Class II: Suspension-Sensitive Species. LCjqg values for 24-hour exposure to fuller's earth were between 1 and 10 g 17}. The sensitive species (white perch, bay anchovy, and juvenile menhaden) were tested at Hallowing Point (Sherk, O'Connor, and Neumann, 1973); their habitat preference with tolerance to fuller's earth was not correlated. Although specific LCj,g values could not be determined, three important commercial species (the striped bass, croaker, and weakfish) were in this general class. 23 (c) Class III: Highly Sensitive Species. Twenty-four-hour LC, values were less than or equal to 1 g 1-! of fuller's earth. Highly sensitive species were Atlantic silverside (24-hour LCj9 value 0.57 g LPB) p juvenile bluefish, juvenile menhaden, and young-of-the-year white perch (Sherk and O'Connor, 1971). Juve- nile bluefish and juvenile menhaden tested at the Bayside Labo- ratory failed to survive in concentrations of 0.8 g 17! for more than 18 hours. Young-of-the-year white perch suffered 100- percent mortality in 0.75 g 17! fuller's earth in 20 hours. The lethal effects of suspended solids on fish species change at dif- ferent stages in the life history. Juvenile white perch are more likely to be killed by low concentrations of suspended solids than are adults. The basis for such age specific differences in tolerance is unknown. When fish are exposed to lethal concentrations of fuller's earth, the gill filaments and the secondary lamellae act as a sieve to trap particles which clog the gill, resulting in asphyxiation (Ellis, 1937). The physical dimensions of the gill increase with the increasing size of the fish (Muir, 1969). As the fish grows and the gill dimensions increase, the openings in the gill filter also increase. Thus, large fish may trap fewer particles, thereby decreasing the lethal effect of a given concen- tration of suspended solids. Another factor that may explain the link between fish size and toler- ance is that small fish have a higher metabolic rate than large fish (O'Connor, Neumann, and Sherk, in preparation, 1976). Small fish demand more oxygen per unit body weight than large fish and therefore are less tolerant to gill clogging. The combined effects of a higher metabolic rate and a finer, more efficient filter render juveniles more sensitive to solids than adults. VI. SUMMARY AND CONCLUSIONS Static bioassays using fuller's earth suspensions and natural sediment suspensions produced significant mortalities in five common estuarine fishes--white perch, spot, Atlantic silversides, mummichog, and striped killifish. Concentrations typically found in estuarine systems during natural events such as storms and flooding, as well as during dredging and dredged material disposal, are within the range of the lethal concen- trations of fuller's earth determined experimentally. Therefore, the possible adverse impact on fish populations of activities producing suspended sediment should be considered. Most fish are capable of avoiding or temporarily leaving a hostile environment. The particulate mineral solids were similar in size distribution to natural sediments likely to be found in estuarine systems. Suspensions of natural sediments affect fish in the same way as fuller's earth but higher concentrations of the natural sediments are required to produce the same level of mortality. Death is caused by anoxia resulting from blockage of small passages in the gills or abrasion of the gill tissue. The effect of finely divided solids is dependent upon concentration, 24 particle-size distribution, and angularity. In addition, other factors, which were uncontrolled and not coyered in this study, must be considered when dealing with natural sediments. These factors may include sorbed toxic metals, high biochemical oxygen demand, and nutrient content. Concentration-response curves were established to predict mortality for selected estuarine fish exposed to suspended particles. Lethal con- centrations of fuller's earth causing a 10-percent mortality in 24 hours of exposure (24-hour LC,q) ranged from 0.57 g 17! for Atlantic silversides CO BALS ied seeps mummichogs. Fish exposed to fuller's earth were clas- sified as tolerant (24-hour LCj9 = 10 g ee): sensitive (24-hour LCj9 > 16 > 1.0 g 17!), or highly sensitive (24-hour LGiigh le Om ealwea)eaaeihe use of lethal concentration levels causing 10- or 50-percent mortality over a defined period of exposure (hours or days) to establish suspended solid criteria is customary and useful. However, this procedure ignores the biologically significant sublethal effects of suspended solids on estuarine Organisms. The tolerances of various estuarine fish can be generalized. The most lethal effects of suspended mineral solids were found in: (a) Fish in the lower trophic levels (anchovies, Atlantic silversides, and juvenile white perch), (b) juvenile fish, and (c) species with high oxy- gen requirements. Species with very low oxygen requirements only succumb to very heavy concentrations of suspended solids, or not at all. These degrees of tolerance tend to be correlated with species habitat preferences. Pelagic (open water) and littoral (shoal water) fish were all affected by suspensions of solids, but to widely varying degrees. Benthic (bottom- dwelling) species that live in or at the mud-water interface were the least affected. Dredging and dredged material deposition (particularly open-water disposal) should be timed and located, if possible, to: (a) Avoid spawn- ing grounds and times, and also areas used by juvenile fish; (b) avoid areas used by lower trophic level fish, particularly filter-feeders; and (c) avoid areas used by pelagic and littoral fish with high oxygen require- ments. Adequate knowledge of local conditions at dredging and dredged material disposal sites is essential for preproject decisionmaking; i.e., species present (seasonal and resident), habitat preference, life history stages, sediment types, sediment chemistry, sediment concentrations, and probable duration of exposure. 25 LITERATURE CITED AMERICAN SOCIETY OF TESTING AND MATERIALS, "'Particle-Size Distribution of Coating Clay,'' Publication No. T 649 su-68, Philadelphia, Pa., 1968. BERKSON, J., "A Statistically Precise and Relatively Simple Method of Estimating the Bioassay with Quantal Response," Journal of Statistical Soctety of America, Vol. 48, 1953, pp. 1069-1085. CAMERON, J.N., and DAVIS, J.C., "Gas Exchange in Rainbow Trout (Salmo gatrdnert) with Varying Blood Oxygen Capacity," Journal of Fishery Research Board, Vol. 27, No. 6, 1970, pp. 1069-1085. EUROPEAN INLAND FISHERIES ADVISORY COMMISSION, ''Water Quality Criteria for European Freshwater Fish," Report on finely divided solids and inland fisheries, EIFAC working party on water quality criteria for European freshwater fish, EIFAC Technical Paper, No. 1, 1964. ELLIS, M., "Erosion Silt as a Factor in Aquatic Environments," Ecology, Vole 1s NIS6 5 pps tZo 42% ELLIS, M., "Detection and Measurement of Stream Pollution," U.S. Bureau of Fisheries Bulletin, Vol. 48, 1937, pp. 365-473. FOLK, R.L., "Petrology of Sedimentary Rocks,' University of Texas, Austin, Tex., 1968. HERBERT, D., and MERKENS, J., ''The Effect of Suspended Mineral Solids on the Survival of Trout," Internattonal Journal of Atr and Water Pollution, Vol. 5, 1961, pp. 46-55. HILDEBRAND, S.F., and SCHROEDER, W.C., "Fishes of Chesapeake Bay," U.S. Bureau of Fisheries Bulletin, Vol. 43, 1928. MASCH, F.D., and ESPEY, W.H., "Shell-Dredging - A Factor in Sedimentation in Galveston Bay,'' Technical Report No. 7, Center for Research in Water Resources, University of Texas, Austin, Tex., 1967. MAY, E.B., "Environmental Effects of Hydraulic Dredging in Estuaries," Bulletin No. 9, Alabama Marine Resources, Dauphin Island, Ala., 1973, pp. 1-85. MUIR, B., ''Gill Dimensions as a Function of Fish Size," Journal of Fishery Research Board of Canada, Vol. 26, 1969, pp. 165-170. O'CONNOR, J.M., NEUMANN, D.A., and SHERK, J.A., "Sublethal Effects of Suspended Sediments on Estuarine Fish," (in preparation, 1976). PERKIN-ELMER CORPORATION, "Analytical Methods for Atomic Absorption Spectrophotometry,'' Norwalk, Conn., 1971. 26 RICKER, W.E., ''Stock and Recruitment," Journal of Fishery Research Board of Canada, Vol. 11, No. 5, 1954, pp. 559-623. ROGERS, B.A., ''The Tolerance of Fishes to Suspended Solids," M.S. Thesis, University of Rhode Island, Kingston, R.I., 1969. SHERK, J.A., and O'CONNOR, J.M., "Effects of Suspended and Deposited Sediments on Estuarine Organisms, PHASE II, N.R.I. Reference No. 71-4D, University of Maryland, College Park, Md., 1971. SHERK, J.A., O'CONNOR, J.M., and NEUMANN, D.A., “Effects of Suspended and Deposited Sediments on Estuarine Organisms,'' PHASE II, N.R.1I. Reference No. 72-9E, Annual Report Project Year II, University of Maryland, College Park, Md., 1972. SHERK, J.A., O'CONNOR, J.M., and NEUMANN, D.A., "Effects of Suspended and Deposited Sediments on Estuarine Environments," Second Inter- nattonal Conference, Estuartne Research Federatton, Myrtle Beach, SiGe OCC LOM or SHERK, J.A., O'CONNOR, J.M., and NEUMANN, D.A., "Effects of Suspended Sediments on Selected Estuarine Plankton,'' MR 76-1, U.S. Army, Corps of Engineers, Coastal Engineering Research Center, Fort Belvoir, Va., Jan. 1976. SOIL TESTING AND PLANT ANALYSIS LABORATORY, "Laboratory Procedures,'"' Cooperative Extension Service, Athens, Ga., 1970. SPRAGUE, J.B., ''Measurement of Pollutant Toxicity to Fish, I. Bioassay Methods for Acute Toxicity,'' Water Research, Vol. 3, 1969, pp. 793-821. STICKNEY, R.R., “Effects of Intracoastal Waterway Dredging on Ichthyofauna and Benthic Macroinvertebrates,"' Skidaway Institution of Oceanography, Savannah, Ga., 1972. TRASK, P.D., Recent Marine Sediments, 2d ed., Dover Publications, New York, 1968, pp. 736. 27 tot ae, ‘ eae * emia eee bi Nye iy Hat TUR We i na rsterais | Mt eeigah Eanes gat Ces mh PAOLO “ie We ra w Cane °j Fr oH, eo; a ba ra Hy y 7 x Wave Ky Wwe en eM 7 PVT CO pore OG i r aie are tat ae ii ht i ab : i \ Mees Ve ‘ , U ay tr * - iy ay ey 1 ff | H f ors Paty Fe | ae i a a ; wp rye a ; ant aT et ee : re i he Lah t a ( Ly APPENDIX ANAYLSES OF SEDIMENTS I. INTRODUCTION Experimental work during 1971 and 1972 utilized artificial, commercially available mineral solids to provide base-line data for biological effects of (a) concentrations of solids, (b) different particle-size distributions, and (c) different mineral types of solids. Work during 1973 concentrated heavily on the biological effects of naturally occurring sedimentary material which was collected by anchor dredge at Long Point (38°29'30" N., 76°39'45" W.) in the Patuxent River, Maryland, and stored in large polyethylene tanks before use in the experi- ments. The sediment surface was covered with a layer of water (salinity range 4 to 6 parts per thousand) to maintain natural ionic equilibria between the sediment and water, as would naturally occur in the Patuxent River. A microoxidized sediment layer developed at the sediment-water interface in tanks after a few days of storage. This appendix contains the results of analyses which were performed on both the commercially available mineral solids and the naturally occur- ring sediments. Sediment characteristics measured were organic matter con- tent (weight loss on ignition), inorganically bound heavy metals (atomic absorption analysis), and particle-size distributions (settling diameter analysis). The particle-size distributions were determined in distilled water, and may represent the basic or fundamental unit particles which can form aggregates with other units and be strongly bound by molecular and atomic forces. These composite units are stable under dispersion methods. Also, the basic particles may form agglomerates in saline water. These com- posites are relatively weakly bonded by electrostatic forces, surface tension, and "sticky" organic matter. II. MATERIALS AND METHODS 1. Size Distribution. Fuller's earth (Fisher F-90) and kaolinite (Hydrite-10, Georgia Kaolin Company) were the artificial sediments (mineral solids) used in this study. Particle-size distributions of these materials were determined by the sedimentation method (American Society of Testing and Materials, 1968) for paper-coating clays. In addition, a finer particle-size distribution of Silica (Si09) was generated from a commercially available Fisher No. S-135 by allowing these solids to settle for 25 minutes through a specified dis- tance in a column of distilled water at 20° Celsius. The solids finer by weight than 15 micrometers were calculated to be remaining in suspension in this column of water from tables presented by Trask (1968) and from Casagrande's nomographic solution of Stokes' law given in American Society 29 of Testing and Materials (1968). The suspended particles were decanted, ovendried for 24 hours at 100° Celsius, ground fine with a porcelain mortar and pestle, and analyzed for size distribution by the American Society of Testing and Materials (1968) method performed for the other mineral solids. This particular size distribution of Si0) particles is referred to in this report as less than 15 micrometers SiO». The natural sediments collected from the Patuxent River were analyzed by a slightly modified procedure from the above method. Preliminary work showed that this material was approximately 75- to 80-percent salt and water by weight. Appropriate triplicate volumes of this natural material were removed from the holding tanks. These volumes were calculated to contain between 5 and 10 grams of dry solids (inorganic). Also, these volumes were corrected upward for the amount (weight) of organic matter present. These quantities of solids were placed into large Pyrex beakers (1-liter capacity) and an appropriate amount of 30 percent hydrogen peroxide (H202) was added to each beaker. The amount (volume) of H 09 (30 percent) needed to oxidize the organic matter present in the sediment was found to be a volume which would produce a final concentration of H202 in the sediment volume of approximately 5 percent. The oxidation reaction was quite violent initially. The reaction was allowed to proceed overnight in a hood with air bubbling slowly through the sediment-H 209 mixture to remove the excess H 90>. When gas evolution had ceased the following day, 750 milliliters of deionized glass-distilled water were added to each beaker. The sediment was resuspended by stirring with a glass rod and allowed to settle. The supernatant was carefully decanted and another 750 milliliters of deionized glass-distilled water rinse were added to each beaker. A 0.2-milliliter sample of supernatant water was then taken from each beaker and the dissolved ion concentration of each solution was determined with the freezing-point depression osmometer normally used in our hematolo- gical analyses. Salt concentration was read from a standard curve relat- ing freezing-point depression and osmolal concentration to sodium chloride (NaCl) concentration in milligram kilogram™! water. If the salt concen- tration was greater than 300 milligrams NaCl kilogram! water, the suspen- sion was allowed to settle, the clear supernatant was decanted, and an additional rinse of 750-milliliter deionized distilled water was added to each beaker. The sediment was resuspended and allowed to settle. The clear supernatant was decanted and the beaker containing the washed sedi- ment made up to 500 milliliters with fresh, deionized glass-distilled water was placed into an ultrasonic bath (45 kilohertz) for 30 minutes. Then, the suspension was placed into a glass cylinder, made up to volume with deionized distilled water, and the analysis followed as described in American Society of Testing and Materials (1968), except that the dis- persing agent, sodium pyrophosphate (NayP207), was not added. Values are reported as percent by weight remaining in suspension (percent finer than) plotting against equivalent spherical diameters according to Stokes' law. 30 2. Organic Matter Content. Samples of the natural sediment collected from the Patuxent River at Long Point were ovendried for 24 hours at 100° Celsius, ground fine with a porcelain mortar and pestle, and ashed for 3 hours at 500° Celsius. Organic matter values are reported as percent loss of dry weight on igni- tion. There was no appreciable loss of inorganic carbonate during the ashing procedure as evidenced by nonsignificant weight losses of calcium carbonate (CaC03) samples which were ashed along with the ovendried natural sediments. 3. Heavy Metals. Amounts of extractable cations in the mineral solids and the natural sediment samples were determined with mild acid extraction and atomic absorption analysis at the Seafood Processing Laboratory, Crisfield, Maryland. Routine procedures for inorganically bound cations, as des- cribed by Perkin-Elmer Corporation (1971) and Soil Testing and Plant Analysis Laboratory (1970), were conducted for zinc, copper, iron, manga- nese, lead, cobalt, nickel, chromium, and cadmium. Mercury values reported are for total mercury from sediments digested for 1 minute in boiling aqua regia (Dow Method, CAS-AM-70.13, revised 22 June 1970, Chlorine Insti- tute, Madison Avenue, New York, New York). Metal values are reported as milligram kilograms! dry weight of solids. III. RESULTS AND DISCUSSION 1. Size Distributions. Particle-size distributions of the extremely fine mineral solids and natural sediment used in this project are presented in Figure A-1 and Table A-1. Useful descriptions of these materials ranked coarsest to finest by median size are as follows: Patuxent River silt (composite less organic matter fraction,11.5 percent of dry weight), median size = <0.8 micrometer, <2 micrometers = 72 percent; fuller's earth, montmorillonite and attapulgite (Fisher No. F-90), median size = <0.5 micrometer, <2 micrometers = 82 percent; and kaolinite,Hydrite-10, (Georgia Kaolin Com- pany), median size = <0.5 micrometer, <2 micrometers = 92 percent. These data have been presented in such a way that graphic solutions (Folk, 1968) and mathematical calculations (Trask, 1968) can be used to determine the second, third, and fourth moments of these distributions. Additional size-distribution analyses for the natural sediments (by date of collection) are presented in Figure A-2 and Table A-2. Median sizes ranged from a high of approximately 1.1 to a low of <0.5 micrometer (August collection). Fraction by weight finer than 2 micrometers ranged from a high of approximately 82 percent to a low of 65 percent (August collection). These particle-size distributions of solids used in our work (Tables A-1 and A-2, Figs. A-1 and A-2) are comparable with those reported by May (1973) in the mudflow from a shell dredge (Table A-3). 3| Pct Finer by Weight 50 60 70 80 90 95 62.5 Figure A-1. Patuxent River silt Fullers earth ay Hydrite-lO Stokes Diameter [EM Particle-size distribution of sediments. 32 Table A-1. Particle-size distributions of artificial sediments.1 Fuller's earth Hydrite-10 (PCE Eimer) percent finer = fraction (expressed as percent) finer by weight than Stokes' diameter (D) in micrometers. 33 40 Collection Date Line | igs 50 UA Nae 2—5 14 Mar, 1973 5 9 uA I2 June 1973 5 = 27 Aug. 1973 1,6 = 70 25 Sept. 1973 2,3 Salk be ae 2 80 @ 2S ~ 90 oO a 95 98 99 7 8 9 10 i (Phi) 7.8 3.9 1.95 0.98 0.49 [LM Stokes Diameter Figure A-2. Particle-size distributions of natural Patuxent River silt samples (two replicate determinations) collected by anchor dredge at Long Point. 34 °Z-V 2In3Ty UT SeUTT 0} IeyzeI sasayqueted utr etocanN *si19JOMOIOTM UT @ SRSIIIGD ,S9303S ue BHerEA Mel our Gueszeds: se 2 OBS IE) ROE = Ieuty SEE <— 324) (9) (zouts 29d) (D (o (zeutj 404) ( @ (aeutz 204) (a) (@ = (zeutz 454) (s) qd (r) 1° £261 3utinp qurog 3uoy 2@ paydaT[oo Serdmes quowtpes IoATY uexnqeg [eInzeu oATIeIUSSeIdeI Fo suoTINqt413Istp Geeaaee °Z-V eTqeL SIS) Table A-3. Particle-size percentages by weight of suspended solids in the mudflow from a shell dredge (from May, 1973). Meters from Size range (pct by weight) discharge 2. Organic Matter Content. Organic matter content of natural sediment samples tended to increase throughout the summer of 1973 from a low of 8.9 percent in June to values in excess of 11 percent in August and September (Table A-4). A comparison of mean organic matter values (Table A-5) showed that these differences between earlier and later samples were significant and may indicate sig- nificant importation of organic matter, which has settled out at Long Point from marshes lining the shores of the Patuxent watershed. These organic matter values are as high as those reported by Masch and Espey (1967) for Galveston Bay. Organic matter analyses were also conducted on the mineral solids. No significant weight loss from ashing was detectable in the fuller's earth solids. Substantial weight losses in the kaolinite (about 11 percent of dry weight) were attributed to loss of bound water (at temperatures of 500° Celsius) associated with these paper-coating and pigment-extending clays (Michael Taranto, Georgia Kaolin Company, personal communication, LOS) ie 3. Heavy Metals. The mineral solids contained metal amounts that were considered bio- logically insignificant (Table A-6). The values reported for Patuxent silt are in the "natural" range of metal amounts found in similar estuarine salinity ranges by Huggett (Virginia Institute of Marine Science, personal communication, 1973) in the York, James, and Elizabeth Rivers which drain into the Virginia part of the Chesapeake Bay system. 36 Table A-4. Organic matter content of natural mud collected by anchor dredge from the Patuxent River (Long Point). Collection date Sample no. SeERuoG (1973) 17 June 1 1.0038 0.3174 2 O22 0.4594 3 ORS 27.0 0.1463 28 June 1 0.3808 0.1703 2 0.4127 0.1846 3 0.6079 OR2i7al'9 14 July 1 0 0.2268 2, 0 0.3545 27 Aug. 1 11.448 0.8321 0.3397 2 11.461 0.7849 0.3205 3 11.970 0.6712 0.2740 4 12.648 0.4317 0.1762 eee 11ese7 = 0.5038 | 0.124 25 Sept. 1 11.4217 + 0.4881 0.1993 2 LUG 8750 2 OsSist 0.2095 3 11.2200 + 0.4626 0.1889 1samples were dried for 24 hours at 100° Celsius, ground fine with a mortar and pestle, then ashed for 3 hours at 500° Celsius. Organic matter values reported are percent loss of dry weight on ignition. 37 Table A-5. Comparison of means of organic matter determinations by collection date. 14 July | 27 Aug. Sample collection dates (1973) 17 June [meena leer | 001 | p<0.001 | p<0.001 28 June p<0.001 | p<0.001] p<0.001 14 July p<0.001 N.S. Dias 4 seen le leat tio asi N.S. 1ST s) 0) (A oe ee oe |e nene | Fon eC omparison not significant. 1Comp t significant Table A-6. Inorganically bound cations in artificial and natural sediment. Element Hydrite-10 Fuller's earth Patuxent silt X + S.E.x (N = 13) Zn 56) O20) Cu AVA Ole Fe 2100.0 + 94.0 Mn 2300.0 + 260.0 Pb <10.0 Co <4.0 Ni <4.0 Cd 1.0 Cr <3.0 Hg <0.2 lExtraction by 0.075 N HC1-H»SO, and analysis by atomic absorption spectroscopy. Values are milligram kilogram. 2analysis not made. 38 d3,gcn° L£e9 OC=9 LR 5,0u dagicn* €0720L “€000-0-LL -Z/MOVG 30P1}U0D ‘*ieqUaD YoIeeSey BuTIseUTSUq TeIseoD °S*f :seTaes “AI «°O@-9Z *‘ou aeded Teotuysey, *1eqUaeD YyoARPeSsaYy B3uTIsesuTsuq Teqseop *S°N :seTseg “III ‘zoyjne qutof ‘*y°q ‘uuewnsay “II *eTITL “I ‘satsodep [TerzeuTy] *¢€ ‘“squeuTpes pepuedsns *zZ “sjueuTpas *| *gouetezeid Jeqrqey pue se8eqjs A1OJSTY-esTT JUeTZTJTP JO YSTJ suTAeNnqse uo ainsodxs jo syqyZueT snotazea jo joezjJa ay pue oats yoeford ayQ je sjueutpes pepuedsns jo uotjeirjquedu0D pejedtotque eyq uodn peseq 3uTyeu -uoTSstoep qoefoadezd 10} uot eUWAOFZUT sUTT-aseq septaoid Apnys stuy ‘gz *d : Audessottqra (€000-0-1L-ZZMOVa § 203UeD YIResey ZuyiseuT3uq TeqIseog *S*n — 39e19U0D) OSTY (07-94 “OU £ AaqUAaD yoivesay BuTiseuzZuq Teyseop *s*n — teded JTeoTuyoey) “TIT : *d gE "Q/6| ‘ZeqUeD YOTeaSey SuTseuT3uUq Teqseop *S'n : "eA SATOATeg Jioqg — *[*Te Ja]°**uueWNEN *y°qd ‘10uU0D,O0 ‘w'r 4q / YSTJ euTIenjse uo sjueWTpes pepuaedsns jo sjdezFe TeYIST "Wf ‘z0uu09 0 d3igcn° Le9 0¢-9/ :ou dagicn* €0ZOL “€000-0-12 -Z/MOVU 2OeB1UOD *10}UeD YoIeeSey ZBuTAveuTSuq TeqseoD °S*n :seTias “AI ‘07-92 ‘Ou aeded TeotTuydey ‘“*1zeqUeD YDIeasey ZuTiseuT3uq TeqseoD *S*N :seTazesg “TIT ‘“Aoyane jutof ‘*y°q ‘uuewneN “TI *eTITL ‘I ‘sqtsodep TerzeuT *¢ ‘“‘squewtTpes pepuedsng *Z *squeUtpas *1 *gouetejeid JeqTqey pue ses’eqs ALORSTY-esTT JUeAeTJTp Jo ysTJ auTienqsa uo ainsodxs jo syzBueT snoTzeA fo JoezJe Vy pue oats qoeford ay ye S]UeUTpes pepuedsns jo uoTJeAjUedU0D pejedtToTjue ey uodn peseq BuTyeUW -uoTSToep .oefordead aoF uoTJeWUAOJUT BUTT-eseq septTaAoad Apnqs sty ‘gc *d : Aydessottqta (€000-0-L2-ZZMOVd * 1eqUeD YyoTeaseYy SupiseuT3ug Teyseop *S*m — 39P19U0D) OSTY (O7Z-9L “OU £ AJaqUaD yoaeesey dupisauTdsug ~Teq3seop *s*n — teded [Teotuydsey) “TTT : °d gE “9/6, ‘ieqUeD YoIResey BuTiseuT3sug Teqyseo) "Ss*n : "eA SATOATeg 3404 — *[*Te Je] ‘*cuueumey *y"q ‘10uU0D,C ‘wee Aq / ysty eutzenjzsa uo sjuewrpes pepuedsns jo sz0eFze TeYIOT "We Sz0uU0D.0 daigcn* £29 O¢=9L 30u dagicn* €020L “€000-9-12 =ZLMOVA 30P1}U0D *AeqUeD YDIeeSeYy BuTIseuTSUq TeIseOD “*S*y :seTies "AI °O7@-9L ‘ou aeded Teotuydey, ‘*AzeqUeD YyOAeesSeYy BuTAVeUTSUq Teyseop *S°N :seTszeS “TIT ‘“‘xzoyjne jutol ‘*y'q SuuewneyN “TI “eTITL ‘I ‘°satsodep TerzeuTW *¢€ ‘“‘sjUewWTpes pepuedsns *Z “*sjueUTpes *1 *aouetejeid qeaqtqey pue seseqs AZOISTY-eFTT JUereTJIP JO ysTJ supaenqsa uo ainsodxe jo syz8ueT snotiea jo joezjze oy pue eats joofoad ayq qe sjusutpes pepuedsns jo uotjzeaquesouoD pejedtotjue ayq uodn peseq 3uTyeu -uoTtstoep yoefoadeid a0ojZ uotjJewAOsZuT auTT-eseq saptaorid Apnqs sty ‘gz *d : Aydeasottarg (€000-0-LL-ZLMOVA * 19}UeD YyoIPeSsey SuTIeeuTsUq TeIseoD *S*n — 39e1RU0D) OSTY (OZ-9/ “OU : AeqUAaD yoieesey ZuTiveuT3uq Teqyseog *‘s*n — aaded Teotuyoey) “TTT : *d ge “9/6, ‘1eqUeD YyOATeasey SuTseuT3uq Teqseop *s*n : “eA S1fFOATeg 34a0q — *[*Te Je] ***uuewnsay *y°qd f10uUu0D,.O ‘W'r 4q / ystT} eutienyzse uo sjzueutpas pepuedsns jo sjzoesjJo TePYIST "Wf ‘z0uU0D .0 daigcsn* Lz9 O7-9L “OU dagicn° €07Z0L “€000-0-12 -Z/MOVG 0P1}UOD *1a}UeD YDIvPesey BuUTseUTZUq TeqseoD *S*N :SeTtes “AIL °OZ-9L ‘ou aeded [eopTuyseT ‘AeqUeD yo1Resey BuTiseuTsug qTeaseog “S*n :seTzag “JIT ‘A0YAne AuTof ‘S*y°q ‘uuewneN “II *eTIFL "I ‘sqtsodep [erzouTW °¢ ‘*SqzUeUTpes pepuedsns *zZ ‘*sjUeUTpes *| *gouetejeid jeqrtqey pue se¥eqs AZORSTY-eFTT JUSAeTITP Jo ysT} ouTaenqjse uo ainsodxe jo syq3ueT snotaeA Jo oezza oyQ pue aqts qoefoid ayj ie sjUsuTpes papuedsns jo uotzeajUsoU0D peqedtotque ay} uodn paseq 3uTyEU -uoTSToep yoefordeird 103 uoT}JeWAOJUT BUTT-eSeq sapTAoAd Apnqs sty] ‘gg +d : Aydeasotrqta (€000-9-L2-ZZMOVd $ 193uUeD YoIRESSYy suTiseuTsug Teqseog *S*n — 39e1RUOD) OSTY (07-94 “OU $ AJaeqUeD yoiresey ZuTieeuT3uq Teqseog *s*n — azeded Teotuyoey) “TIT : *d gE = “9/6, ‘2eqUeD YOAeaSey BuTIseeUTsUq qTeaseop “Sn : “eA SaToATeg 3a0q — *[*Te Je] *s*uuewnayy *y°qd ‘10uU0D,0 ‘wie Aq / UST} euTzenjsa uo sjueUTpes pepuedsns jo sjoezFzo TeYIAT "W'r fz0uU09.0 ere ote VAT 215" ee eR Se Si cre NE daigsn* O¢=9/ “ou dagicn* €020L “€000-0-12 “Z/MOVA }0e81}U0D *AeqUeD YoIeasey BuTIseUTSUq [TeIseOD *S*n :seTIes "AI ‘07-94 ‘ou zeded TeoTuysey ‘*1eqUeD YoIeesoeYyY BuTieeuTsug qpeaseop *S'N :setzes “TIT ‘“soyjne qufof ‘*y°q ‘uuewneay “II “eTITL ‘I ‘satsodep [erzeuTW *¢ ‘SjueuTpes pepuedsns *Z ‘sjueWTpes *|1 *aouerzeyeid jeqtqey pue sesejs AOJSTY-eFTT JUeTeTFIP JO YySTJ euTAeN Sa uo ainsodxs jo syq3ueT snotieaA jo Joesza ay, pue e3ts Aoefoid ayQ We s]UeuTpes pepuedsns jo uoTjeijqusou0D pejedtotque eyz uodn peseq 3uTyeu -uoTtstoep yoefoadeid AozF uoTJeWIOFUT sUTT-9Seq septTAoid Apnjs stu ‘gz *d : Aydessortqrg (€000-0-12£-ZLMOVa § 193UeD YyorReseYy BuyTleeuTZuq Teqseog *Ss'n — 29B19U0D) OSTY (07-94 “OU § AaqUaD yoreesey ZutTieeuTZuq Teqseop *s'n — azeded Teotuysel) “TIT : *d gE “Q/6L ‘SXeqUeD YOTPeSey BuTAseUuTsUq Teqaseop *s*n : “ea fAToATeg 340g — ‘*[*Te Je]°**uUeWNAN *y°q ‘1OUUOD,.O ‘w'c Aq / UST} euTIeNjZse uo sjUueUTpes papuedsns Jo sjooFjFo TeYUIST "Wf ‘z0uu0D.0 d3igcn* L£e9 OC=9 eee dagicn* €02OL “€000-9-12 -Z/MOVG 0e1}U0D *AeqUaD YDIesSey BUTIVseUTZUq TeISeOD *S*n :seTres “AI °07Z-9L ‘ou aeded [eotuyse, *AequeDQ YyOAeesey SuTrseUuTsUq Teaseop "S*N :seTazesg “TIT ‘*so0yane qutof ‘*y°q ‘uueuneN “II ‘*eTITL “I °sqtsodep [erleuTW °¢€ ‘SqUsUTpes pepuedsns °*Z ‘sjusaUTpes *1 *aouetezeid jeatqey pue se8eqs AXOISTY-SJTT JUeTeTITp JO ysT} aeutaenjsea uo ainsodxe Jo syq3ueT snotaeA Jo Joasyo oy pue eqts joeford ay Ae SjusutTpeas pepuedsns jo uot eAQUsoUOD pajedtToTiue ey uodn paeseq BuTyeU -uOTSTOOp Joefoadead 1OJZ uoTJewAOJUT |vuTT-eseq saptTaAoad Apnjs sty ‘gz *d : AyderB0tTqtg (€000-0-LL-ZLMOVa § 1eqUeD YyoAPesey ButieeuTZuq [eqseoD *Ss*m — 4oeIRWUOD) OSTY (OZ-9L ‘OU ¢ AaqUAaD yorreesey BZutarseursuyq Teyseop *s*n — Jeded Teotuyoey) “TTT : °d gE ‘9/6, ‘1eqUeD YOIAeesey BuTAseuT3uq qTeaseop “Sn : “eA SatoATeg Jiog — ‘*['Te Jo) ‘**uuewunay *‘y°q ‘1ouUu0D,0O ‘w'r Aq / UST} euTienjse uo sjueuTpes pepuedsns jo sqzoezya TeYyIeT “Wer ‘zouu0D <0 d3.gcn° 129 07-92 “Ou dagisn° €07OL “€000-0-12 -“ZLMOVU 2081QUOD *19}Ua9g YOAReSey BuTAseuTSuq TeqyseoD “Sn :SetTszes “AI °O7@-92 °ou aaded TedTuydey “*ieqUeD YyDieasey BUTAseUT3Uq Teqseop “Sn :seTzes “JIT ‘toyyne qutof ‘*y°q ‘uuewney ‘ITT ‘eTITL ‘I ‘sqtsodep [ezeuTy] *¢€ ‘“‘sjUueWTpes pepuedsns *Z7 ‘*squeUTpes *| *aouetejeid qeqrqey pue se8eqjs ATOJSTY-9FTT JUereTJTp Jo YySTF sutTienqsa uo vansodxs jo sy8ueT snoTaeaA Jo JOeFje ay pue a3zts Aoefoird 93yW We sjueuTpes pepuedsns jo uot}zeAjqUsoUOD pejedToTqjue ayq uodn paeseq BuTyeU -uotstoep qoafordead z0j uotTjewiOjJUT VvUTT-eseq saptAoad Apnjs styl ‘gc cd : AydeaSotTqta (€000-O-L2-ZZMOVd + 19}uUeD YyoITRaseYy SuTiveuT3ugq Te3seop *S*A — 39P1WUOD) OSTY (O7Z=-9L “OU $ AaqUaD yoreesey JutTsvseutTsugq Teqseog *s*n — aeded Teotuyoey) “TIT : *d gE “9/6, ‘XeqUaD YoAvasey BuTreeuT3ug Teqseoy “stn : “ey SATOATEgG Jaoy — *[°Te Je]°**uueumay *y°q f10uUu0D,0 ‘we Aq / usty eutTzenjse uo sjueuwtpes pepuedsns jo sqoezzo TRYIOT "W'f ‘z0uu0D.0 darecn* L729 DEBYL “OU d3gicn* £0201 "€000-0-LZ -Z/MOVG }OBAJUOD *JejUeD YDIRPesey BuTAseuTsuq TeIsPOD *S*N :SeTites “AI ‘07-94 ‘ou azeded TeoTuYyde, *JeqUaD YOTeaSey BuTseuTsUq qTeqseog “Sn :seTazeg “TIT ‘zoy;ne Qutof S*y°q fuuewnsy ‘II “eTITL ‘I ‘satsodep [ereuTW *¢ ‘sqUeUTpes pepuedsns *Z ‘*sjUeUTpes *] *aouetezeid qeqtqey pue sa¥ejs ATORSTY-9FT[ JUeAeFFTTp Jo ysTF ouTzeNnqsSe9 uo oinsodxe jo syj3ueT snotaea jo OezjJe ay, pue aqtTs qoeford ay We sjueutpes pepuedsns jo uotjerjqUsouoD pajedtotjue ay uodn peseq SuTyeU -uoTstoep jyoefoadead 20x uoTJeWAOFUT SsUTT-eSeq sapTAoad Apnys stu "9g *d : Aydea80TT qT (€000-0-LZ-ZZMOVd § 1e3UeD YOITRESeYy SuTiseuTsuq TeIseog *S*N — 30e1IUOD) OSTY (OZ-9L “OU : 1TezUeD yoaeesey SuTaseutT3Zuq Teqseog *s*n — aeded TeoTuyoey) “TTT : *d gE 2 “9/6, ‘2eqUeD YOARasey BuTAseUTSUT qTeqseop *S*N : “ea SATOATeg 340g — ‘*[*Te Je] **cuuewnsay *y°q ‘10UuU0D,0 ‘wir 4q / UST} euTazenjse uo sjuewtpes pepuedsns jo sqoezye [TeYyIeT "Wir f20uu0D.0