Reprinted from the Pubbl. stay., zool. Napoli 33 suppl., 45-60 (1964). A seasonal study of living OSTRACODA in a Texas bay (Redfish Bay) adjoining the Gulf of Mexico by LOUIS S. KORNICKER1 (From the Texas A & M University, U. S. A.) 14 Figures INTRODUCTION This report is based on a field study of living ostracods. The investigation was designed to emphasize features of eeologic interest such as (1) seasonal and spatial variations in ostracod abundance and community composition, (2) the relationship of ostracod distributional patterns to certain environmental factors, and (3) a comparison of the composition of living ostracod populations with assemblages of empty ostracod carapaces in the sediment. LOCATION ANO DESCRIPTION or AREA Narrow, elongate barrier islands are separated from the mainland coast of Texas by a system of estuarine and lagoonal bays (Fig. 1). Redfish Bay is a small bay situated near the Institute of Marine Science, The University of Texas, which was the base of operations for this study. The bay is approxi- mately 16 km long and 4 wide; its area is about 64.7 km2 and its volume at mean tide level is about 22.30 million cubic meters (COLLIER & HEDGEPETH, 1950). The northwestern border of the bay is the Texas mainland. It is sepa- rated from Aransas Bay on the north east and Corpus Christ! Bay on the south by low-lying marshy islands. Harbor Island, a tidal delta, and St. Joseph Island, a barrier island, lie between Redfish Bay and the Gulf of Mexico. The bay is bisected diagonally by a discontinuous chain of linear, man-made islands once used to support a railroad (Fig. 2). As in most Texas bays, Redfish Bay is quite shallow, having a maximum depth of about 2 m. Under certain wind and tide conditions a considerable part of the bay bottom is almost exposed. Water temperature in the shallow bay closely follows air temperature which ranges from 0? C in the winter to 1 The writer gratefully acknowledges the assistance received from Dr. CHARLES WISE, Mr. CHARLES KING, Dr. STUART GROSSMAN and Dr. JOHN CONOVER in this study. The work was supported with funds received from the National Science Foundation (NSF-G-5473; NSF-G-10869) and from the Ollice of Naval Research I Contract Nonr 2119(04)1. i 46 Louis S. Kornicker 40? C in the summer, and averages annually about 25? C. Summer temperatures tend to be more or less constant at about 29? C, moderated by strong southeast winds. In the winter, the temperature may drop as much as 20? C within 24 h, 28?30? 28?00 2 7?30 27? 00' MESQUTO 97?30' 97?00' Fic. 1. Map showing location of Redlish Bay. 96? 30' which sometimes results in below freezing temperatures of short duration. These cold spells occasionally cause the death of large numbers of fish (GINTER & HILDEBRAND, 1951). Seasonal variation of salinity in Red fish Bay is controlled Seasonal study of living OSTRACODA 47 primarily by temperature and rainfall. Low winter salinities are caused by low evaporation rates and seasonal rainfall. The average annual rainfall is about ARANSAS C PASS I GULF OF MEXICO FIG. 2. Map showing position of sample stations in Redfish Bay. 100 cm. The climate according to THORNTHWAITE'S classification (1948) is ? dry subhumid ?. 3 48 Louis S. Kornicker METHODS In order to be certain that samples could be collected from the same location repeatedly, cedar posts were installed at each sampling locality. Five posts were erected about 0.4 km apart on two transects oriented perpendicular to the shore. Transect I is about 4.8 km from Transect II. Sample stations on Transect I were numbered 1 to 5, and stations on Transect II were numbered 6 to 10. Stations 1 and 6 are closest to the shore. It had been the intent at the beginning of the investigation to quantitatively sample the oslracod population in the upper centimeter of sediment cores. However, it soon became apparent that an insufficient number of living ostracods would be STATION 10, NOVEMBER, 1963 CAMPYLOCYTHERE (?) SP HAPLOCYTHERIDEA- PONDEROSA HAPLOCYTHERIDEA PROBOSCIDIALA 10 20 30 40 50 100 150 200 250 100 CUMULATIVE NUMBER OF OSTRACODS COUNTED FIG. 3. Variation in population structure as larger numbers of specimens in a sample are counted. obtained using this procedure without collecting an impractical number of cores. Therefore, the following sampling procedure was developed: A trawl with a flat bottom, about a half meter wide, was pulled in a circle having an estimated radius of 15 m around each cedar post. A weight suspended on a rope stirred up the sediment in front of the trawl, and the leading edge of the trawl scraped the top of the sediment. Sediment and ostracods entering the trawl were caught in a fine- mesh nylon net and ultimately deposited in a 250 ml bottle attached to the back end of the net. After the sampling circle was completed, clay in the sediment was washed from the sample by repeatedly immersing the net in the water. The sample was concentrated in this manner until the sample from each station consisted of 250-500 ml. In the laboratory, each sample was wet sieved through a screen having a mesh size of 125 it,, and 300 living ostracods were removed under a dissection microscope. It was found that by keeping samples cool while in the boat and in the laboratory, Seasonal study of living OSTRACODA 49 ostracods could be kept alive at least 24 hours. Removing ostracods during this time Is made easy because their location is detected by movements. The ostracods removed from samples were placed for future study in vials containing alcohol as a preser- vative. If only part of the sample was picked by the time 300 ostracods were removed, the number of ostracods in the unpicked part of the sample was estimated in order to arrive at a figure representing the total number of specimens in the sample. Problems of scunpling. Several problems arc encountered in collecting represen- tative samples of ostracods because of the need for a sufficient number of specimens to minimize sampling error. The effect of the number of specimens included in a ITv, . gT , ?, 16) 16) (6P ,461 'G' "01 = S 5000 (6) ,000- 15) /\ \|6) M00- /"^y no) ,000- / 16) isr^. (5] 'TsT II i ? ? i l? N0V DEC FEB MAR APR MAY JUN JUL AUG SEP7 OCT NOV FIG. 4. Average monthly salinities, temperatures, carbon production and ostracod abundance in Redfish Bay. Carbon production figures were supplied by Dr. H. T. OouM. Ostracod abun- dance based on average of all samples. sample on population structure is illustrated in Fig. 3. This figure is based on one sample containing a total of 300 ostracods. It shows the apparent change in compo- sition of the population as the number of specimens picked from the sample increased from 10 to 300. Note that the population structure becomes more or less stabilized only after about 150 specimens are counted. Also note how the number of species increases as more and more specimens are included. In the present study 300 spe- cimens were picked from each sample, but in a few cases it was necessary to be satisfied with 150 specimens. Three of four samples with fewer than 150 specimens were considered inadequate samples and not used in studying population structure. Sampling difficulties also arise when attempting to ascertain the number of ostra- 50 Louis S. Kornicker cods living in a given area. With some organisms such as bacteria or FoR,\MiKirrw,\ this problem is not as acute since they are usually more abundant than ostracods. Unfortunately, it is seldom that as many as 10 living ostracods are encountered in an average size core; and, unless the ostracods are evenly deposited on the bottom, the number of ostracods in a single core will not be representative of ostracod abun- dance in a given area. The use of larger diameter cores may provide a solution, if mechanical problems usually encountered when using large-diameter coring tubes are solved. Adequate numbers of ostracods for studying population structure were obtained in this investigation by using a trawl, but the use of this method for ascertaining BER OF SAMPLES nov DEC FFB MAR APR MAR JN JUL AuG SEP OCT UOV flG. 5. Average monthly abundance of all ostracods, Aurila floriclana, Loxoconcha purisiibrhoinboiclea, and ? remaining species ? in Redfish Bay. Ostracod abundance based on samples containing not less than 150 specimens. the abundance of ostracods living in a given area leaves much to be desired. Duplicate samples collected with the trawl contained numbers of ostracods of the same order of magnitude; however, rough estimates of the number of ostracods in the path covered by the trawl obtained by taking several cores indicate that the trawl captures only a small fraction of the ostracods in the area over which it passes. Therefore, the abundance of ostracods in a trawl sample gives, at best, an index of ostracod abun- dance. It is also probable that a trawl will capture a different percentage of ostra- cods in its path when passing over one type of sediment than over another, so that indices of ostracod abundance may not be accurate when comparing areas containing different sediments. Variations in abundance of vegetation may affect the depth at which a trawl will dig into the sediment and therefore, the number of burrowing ostracods captured. Another sampling problem exists because all species of ostracods do not have Seasonal study of living OSTRACODA 51 the same living habits. For example, some species prefer burrowing in sediment, whereas others prefer crawling on vegetation. A sample obtained from a coring tube that pushes vegetation aside will contain fewer plant crawlers than live in the area sampled by the coring tube. On the other hand, a sample from a trawl that rides on the vegetation will contain too few sediment burrovvers. Clearly, obtaining an unbiased and adequate sample is one of the major problems confronting students of living ostracods. In the data presented in this paper, ostracod .UF,IL. FLORIDA NA ?i / \ - ^% -/ s*v --REMAINING SPECIES AURiLA fLORlOANA ? LOXOCONCHA PURlSUBRHOMBOlOE A * REMAINING SPECIES FIG. 6. Relationship between abundance of Aurila iloriduna, Loxoconcha purisubrhomboidea, ? re- maining species ? and salinity. abundances at stations sampled have been averaged for each month; and it is hoped that trends established are real and not the result of imperfect sampling procedures. SEASONAL DISTRIBUTION OF OSTRACODS Fig. 4 shows the average monthly values for salinity, temperature, carbon production and ostracods at stations sampled. The number next to each datum point indicates the number of measurements used in obtaining averages. During winter months the water in Redfish Bay has low salinities, low temperatures, and low carbon production. During summer months, salinities approach that of normal marine water, and temperatures and carbon production 52 Louis S. Kornicker increase. Carbon production is considered here as a measure of food available for ostracod consumption. The graph of ostracod abundance in Fig. 4 was derived by averaging samples collected during a given mouth. All samples were included in this ave- rage regardless of the number of ostracods per sample. Samples contained as little as 24 to as many as 8000 ostracods. The ostracod abundance curve sug- gests that more ostracods are present in Redfish Bay during summer months than during winter months. Ostracods are more abundant when the water has normal marine salinities, high temperatures, and high carbon production. J i I STATION INOV|DEC|FEB|MAH,APR|MAY|JUN,JULMUG|SEPI)OCT|NOV| 1958 1959 AURILA FLORIDANA Benson and Colemar FIG. 7. Percent of Aurila floridana in samples. 9 Z: 10 | NOV| DEC | FEB| MAPI APR|MAY | JUN | JUL | AUG (SEPTi OCTl NOVl 95B 1959 LOXOCONCHA PURISUBRHOMBOIDEA Edwards FIG. 8. Percent of Loxoconcha purisubrhom- boideu in samples. Fig. 5 shows the averaged monthly abundance of all ostracods and also of certain species. The curve for all ostracods has been smoothed by eliminating from averages samples containing fewer than 150 specimens. The omitted samples are considered to be in error due to faulty operation of the trawl. Although the total ostracod curve in Fig. 5 differs in detail from the curve in Fig. 4 which included all data, the trend showing more ostracods living in the bay during summer months has not changed. The species that dominated almost all samples collected in Redfish Bay has been tentatively identified as Aurila -floridana BENSON & COLEMAN (1963). The species normally second to A. floridana in abundance and dominating a few samples has tentatively been identified as Loxoconcha purisubrhomboidea EDWARDS Seasonal study of living OSIHACODA 53 (GROSSMAN, m. s.). The remaing 5-7 species found in samples were usually present in small numbers and here have been lumped together in ? remaining species ?. The curves in Fig. 5 indicate that the abundance of A. floridana, L. purisub- rhomboidea and ? remaining species ? are all greater in summer than in winter. It is difficult in a field study to determine which property of the environ- ment is affecting the ostracod population. In the present study ostracods be- came more abundant as the salinity, temperature and carbon production in- creased. It is not possible to conclude with a degree of certainty that any one of these environmental parameters is more important than another. Also, STATION o o t _lNOV|DEC|FEB|MAR|APR|MAY|jUN|jUL|AUGteEFTlOCT|NOVr 958 1959 REMAINING SPECIES FLG. 9. Percent of ? remaining species ? in samples, it is always possible that an important environmental parameter was not measured. The narrowing down of the effect of isolated environmental para- meters such as temperature or salinity on ostracod abundance is best handled in the laboratory. Laboratory experiments reported by KORNICKER & WISE (1960) show that A. floridana (= Hemicythere conradi HOWE & MCGUIRT) collected from Redfish Bay does not tolerate temperatures lower than 6? C or higher than 36? C, and salinities lower than 6 %0 or higher than 65 %o- The salinities observed in Redfish Bay during the present study are well within the tolerance limits of A. floridana, and it is therefore inferred that the increase in salinity noted during summer months did not contribute directly to increasing the abundance of A. floridana. Nevertheless, it is possible to show a relationship between salinity and the abundance of A. floridana and other species. This has 54 Louis S. Kornicker been done in Fig. 6 which shows ostracod abundance plotted as a function of salinity. Although a fair correlation exists between salinity and ostracod abun- dance, it is not necessarily a cause and effect relationship. If, for example, an increase in temperature results in an increase in ostracod abundance, salinity would also be found to correlate with ostracod abundance because high tem- peratures promote evaporation which in turn causes salinity to increase. The range of temperatures observed during the sampling period was within the temperature tolerance limits for A. floridana observed experimentally; but TRANSECT STATION 3 STATION f Md'5.5*t.22mml 50- S.0,'6 I * Md-5 9*1 iTmml 50- SO. = 6.2* TRANSECT > 25 0625 0039 50- SO * " 6* uo. 2.B*ti 50- SO ? 3.4 4 > 25 0625 0039 25 0625 0039 SEDIMENT CHARACTERISTICS AT REDFISH BAY SAMPLE STATIONS FIG. 10. Histograms showing distribution of size classes in sediments at each station. Size class greater than 2 phi consisted mostly of shells. measurements made between sampling periods show that, occasionally, during winter storms, the water of Redfish Bay reached a low of 2? C, which is 4 degrees below the tolerance limit of A. floridana. It is inferred, therefore, that low winter temperatures may be a factor in decreasing ostracod abundance during winter months. However, further work is necessary to document this hypothesis. Little is known about the food tolerance limits of ostracods. It seems logical to assume that ostracods will increase in abundance if more food is made available. The increase in ostracod abundance with high carbon production suggests that food availability may be affecting ostracod abundance in Redfish 10 Seasonal study of living OSTRACISM 55 X-.. ?v .0 -'\'- .0 ^\ % " %^^ ,0 - '? - ,0 - 20 10 40 10 60 L0*0C0NCHfl PUBiSUBRMOMBOiDEfl (%] Frc 11. Relationship between relative abundance of Aurila floridana and Loxoconcha purisub rhomboidea. V. 90 ? B? - ' \ ? ,0 y ? h? . \ \ . \ \ ? r - ,0 ? ? ,o ? &0 60 70 REMAINING SPECIES LESS LOXOCONCHA PURISUBRHQMBOIDEA (%| Frc 12. Relationship between relative abundance of Aurila floridana and 11 remaining species ? 56 Louis S. Kornicker Bay. However, it is not possible to more than infer a cause-and-effect relationship between ostracod abundance and food availability at this time. POPULATION STRUCTURE Fig. 7, 8, 9 illustrate the sample content on a percentage basis of A. flori- dana, L. purisubrhomboidea and ? remaining species ? in monthly samples from REMAINING SPECIES LESS ftuRiLA FLORIOANA 1% Fic. 13. Relationship between relative abundance of Loxoncha purisubrhomboidea and ? remaining species ?. each station. These figures indicate that seasonal trends differ from station to station; but perhaps the most significant observation to be derived from these figures is the remarkable similarity in population structure within Red- fish Bay. Although temperature and salinity are fairly uniform throughout the bay during any given time, differences in vegetation and sediments at each station might lead to predictions that populations vary considerably from station to station. The sediment, for example, as shown in Fig. 10, was consi- derably different at each station; but these differences had no readily apparent effect on the ostracod population. Fig. 11, 12, 13 illustrate relationships between A. floridana, L. purisub- rhomboidea, and ? remaining species ? in samples containg more than 150 speci- 12 Seasonal study of living OSTRACODA 57 mens. The relative abundance of L. purisubrliomboidea and ?remaining species? varies inversely with the abundance of A. floridana, whereas a direct relat- ionship appears to exist between the relative abundances of L. purisubrhom- boidea and ? remaining species ?. It is inferred from this that the changing en- vironment has a greater effect on the total abundance of A. floridana, than it does on either L. purisubrliomboidea or ? remaining species ?. It is also inferred SEASONAL VARIATION IN COMMUNITY STRUCTURE AT STATION 1 OEC 9 FEB 5 MAR | MAR 23 PERlSSOCYTHERIDEA RUG AT A PARACVTHERET TA MULTICARINATA HAPLOCYTHERIDEA PONDED OSA HAPLOCYTHER^CA PROBOSCIDIALA CYPRIDElS Cf. C. TOROSA (JONEsf XESTOLEBERIS sp_ CAMPLOCYTHERA (?) 50 CVTHERURA JOHNSO.MI LOXOCONCHA PURlSUBRHOMBOHCEA AURlLA FLORIDANA \\ A PERlSSOCYTHERIDEA RuGATA PA RACY THERE TTA MULTICARINATA HAPLOCYTHERIDEA PONOEROSA- HAPLDCYTHERIDEA PROBOSCIDIALA CYPRIDElS Cf. C TOROSA (JONES) XESTOLEBERIS SP~ CAMPLOCYTHERA I?) sp CYTHERURA JOHNSON I LOXOCDNCHA PUR1SUBRH0MB0IDEA AURlLA FLORIDANA /.'OTY CARAPACES W SEC VENT (JUNL iSl WEIGHTEO AVERAGE GF ALL SAMPLES PERlSSOCYTHERIDEA RuGATA PA RACY THE RE TTA MULTICARINATA HAPLOCYTHERIDEA PONDEROSA HAPLOCYTHERIDEA PROBOSClOlALA_ CYPRIDElS cf. C TOROSA (JONES) XESTOLEBERIS Sp_ CAMPLOCYTHERA (?) sp CYTHERURA JOHNSON! LOXOCONCHA PURISU8RH0MB01DEA auRlLA FLORIDANA JULY 23 AUG. 18 Frc. 14. Osiracod population structures in samples from station 1, averaged population structure, and population structures of empty carapaces collected from sediment at Station 1. that the changing environment has an approximately equal effect on total abundance of L. purisubrhomboidea and ? remaining species ?. The relative merits of analyzing the distribution of organisms by means of absolute abundances and percentage frequencies have been compared by several investigators (SAID, 1950; BENDA & PURI, 1962) who have concluded that absolute abundances are more useful than percentage frequencies. In Redfish Bay seasonal environmental differences are reflected by changes both in absolute abundances and in percentage frequency. Therefore, it is sug- gested that in distributional studies both absolute abundances and frequency percentages be used independently as environmental indicators. In a study .13 58 Louis S. Kornicker of fossil ostracods, a decrease in absolute abundance not accompanied by change in percentage frequency probably reflects a higher sedimentation rate rather than a change in environment. COMPARISON OF LIVING AND DEAD POPULATION STRUCTURES In Fig. 14, the population structure at station 1 is illustrated as a pyramid of species. The length of each horizontal bar is proportional to the percentage of the indicated species in a sample. These diagrams show that common species are present in all samples, but rare species appear to come and go. It is not unlikely that if a larger number of specimens were included in the samples, say 1000 instead of 300, most of the rare species would have been present in all samples. The center-left pyramid in Fig. 14 is the average of all samples, whereas the center-right pyramid is a weighted average of all samples. These pyramids should approximate the average annual population structure. A question of considerable interest to paleoecologists is: How closely does an assemblage of empty carapaces obtained from the sediment resemble a population living in the area? For this reason, empty carapaces were picked from the sediment at station 1, and the pyramid shown in the center of Fig. 14 was constructed. Although the assemblage of empty carapaces differs from the living population, it is of sufficient similarity to be encouraging to paleo- ecologists. SUMMARY Redfish Bay is a shallow bay having a maximum depth of about 2 m and is located between a barrier island in the Gulf of Mexico and the Texas mainland. Temperature ranges from about 0 to 40? C and salinity from 16 to 37 %0. Living ostracods are more abundant during summer months when water has normal marine salinity, high temperature and high carbon production. Almost all samples of living benthonic ostracods are dominated by Aurila floridana BENSON & COLEMAN. LOXO- concha purisubrhomboidea EDWARDS is usually second in abundance but occasionally is dominant. Ostracod populations are remarkably similar in composition within Red- fish Bay. Seasonal environmental differences are reflected by changes both in abso- lute abundance and in percentage frequency of species. A comparison of the com- position of the average annual population living at one station in the bay with an assemblage of empty carapaces obtained from the sediment showed them to be quite similar. RlASSUNTO La Baia di Redfish e una baia poco profonda che ha una massima profondita di circa 2 metri ed e situata tra una barriera isolata nel Golfo del Messico e la costa del Texas. II campo di variazione della temperatura e ca. da 0 a 40? C e quello 14 Seasonal study of living OSTRACODA 59 della salinita dal 16 al 37%,). Gli Oslracodi vivi sono piu abbondanti durante i mesi cslivi quando l'acqua ha la normale salinita marina, alia temperatura cd alta produzione di carbonio. Quasi tutti i campioni ad Oslracodi bentonici vivi sono dominali da Aurila floridana BENSON e Cott&UTi. Loxoconclui purisubrhoinboidca EDWARDS e solitamente seconda in ordine di abbondanza ma e taloia occasionalmenle dominante. Le popolazioni di Oslracodi sono notevolmente simili per composizione cntro la Baia di Redfish. Stagionali dilfercnze ambicntali producono variazioni sia nclla abbondanza assolula sia nclla ircquenza pcrccntuale dclle specie. Un confronto tra la composizione della popolazione media annuale vivente in una stazione nclla baia con una associazionc di carapaci compleli ottcnuli dal scdimcnto ha mostrato che csse sono totalmente simili. BlULlOUKAl'HY BENDA, W. K., and H. S. Puiu, 1962: The distribution of FORAMINIFERA and OSTRACODA off the Gulf coast of the Cape Romano area, Florida. Trans. Gulf Coast Assoc. Geol. Soc. 12, 303-341. BENSON, R. H., and G. L. COLEMAN, 1963: Recent marine ostracodes from the eastern Gulf of Mexico. Paleontol. Contr. Univ. Kans. Art. 2, 1-52. COLLIER, A. W., and J. W. Hrix;r,iTin, 1950: An introduction to the hydrography of the tidal water of Texas. Publ. Inst. Marine Sci. Univ. Texas 1, 123-194. GUNTER, G. and H. HIIDHHRAXD, 1951: Destruction of lishes and other organisms on south Texas coast by cold wave of January 27-February 3, 1951. Ecology 32, 731-736. KORNICKER, L. S., and C. D. WISE, 1960: Some environmental boundaries of a marine ostracod. Micropaleontol. 6, 393-398. SAID, R., 1950: The distribution of FORAMINIFERA in the northern Red Sea: Cushman Lab. Foram. Research Contr. 1, 9-29. TiiORNTttWAlTE, C. W., 1948: An approach toward a rational classification of climate. Geogr. Rev. 38, 55-94. Dr. L. S. KORNICKER, Dept. of Oceanography and Meteorology, A. & M. University, College Station, Texas, U.S.A. Present address: Smithsonian Institution, United States National Museum, Washington, D.C. 20560, U.S.A. DISCUSSION HARTMANN : You said the number of ostracods in restricted areas was very high. I suppose you mean the number of individuals, not the number of species? KORNICKER: Yes. HARTMANN: And then another thing: you named ?province ? and I think we should not use the name province for biotopes because this is solely for geographical purposes. When you say biotopes, it is more clear. KORNICKER: I use the term province for the geographical area occupied by a particular environment. Do you feel that this would be incorrect also? HARTMANN: If it is a certain geographical area that is occupied by a 15 60 Louis S. Kornicker certain fauna then you can use it. For instance, in Central America, they have a Panamanian Province and a Guatemala Province. BENSON : May I ask for a clarification in semantics? Do you regard biotopc as an habitat or the community? KORXICKER: Habitat. McKtiNziE: The discussion that we have had of provinces seems to suggest that they are rather large in area and can be defined by faunal relationships and FORAMINIFERA too. I wonder if for Bahamas Bank it might not be better to use the term subprovince within the larger area of the Caribbean Province. KORNICKER: I would have to think about this. BENSON: I would like to comment on something that Dr. KORNICKER said regarding the concentration of ostracods in a carbonate province. I used the term in the sedimentary sense. I think it was in about 1953 that DORIS CURTIS introduced into the ostracode literature the concept of energy levels in distri- bution of forms. I know that in my work in Todos Santos Bay I was im- pressed with the apparent control of wave base on shelly fades and shallow sediments. The distribution of certain ornate ostracods seemed possibly to be influenced by the coarseness of the material in which they lived. This of course was an idea that DORIS CURTIS intended to follow up, and in her 1960 paper on the Mississippi Delta she contended that there were many types of orna- mentation as well as the productivity of these ornate forms that was in direct proportion to the coarseness to the material in which it lived. I would suggest, I think it was Dr. ELOFSON who wrote about endopsammose forms which are ornate burrowing ostracods. The ornateness sometimes functions as strengthen- ing against breakage of the carapace according to simple engineering principles. And in some cases spines may extend like cats' whiskers enclosing the setae, to allow the form to work in and about in what I would assume would be like tumbling boulders in an unstable environment. And I was wondering what your thought son this hypothesis might be because the adaption of orna- mentation and structure toward increasing energy levels or the instability of the substrate in which or on which the forms live, might be useful paleoecologic indicator. 16