WorldCat Identities

Ehrhart, Llewellyn M.

Works: 19 works in 20 publications in 1 language and 25 library holdings
Genres: Academic theses  History 
Roles: Thesis advisor, Author, Contributor
Classifications: QL666.C5, 590
Publication Timeline
Most widely held works by Llewellyn M Ehrhart
A study of a diverse coastal ecosystem on the Atlantic coast of Florida : annual report, July 72-June 73 by Haven C Sweet( Book )

1 edition published in 1973 in English and held by 4 WorldCat member libraries worldwide

Genetic structure of the southeastern United States loggerhead turtle nesting aggregation: evidence of additional structure within the peninsular Florida recovery unit by Brian M Shamblin( )

1 edition published in 2010 in English and held by 2 WorldCat member libraries worldwide

Digging behavior of four species of deer mice (Peromyscus) by James Nathaniel Layne( Book )

1 edition published in 1970 in English and held by 2 WorldCat member libraries worldwide

The effects of beach restoration on marine turtles nesting in South Brevard County, Florida by Paul W Raymond( Book )

2 editions published between 1983 and 1984 in English and held by 2 WorldCat member libraries worldwide

The south Brevard coast of Florida is a major nesting ground for the Atlantic loggerhead turtle (Caretta caretta). A beach restoration project was completed in the winter of 1980-81 at Indialantic and Melbourne Beach. A study was conducted to investigate the effects of beach restoration on marine turtle nesting during the summer months of 1981 and 1982. A 3.1 km restored beach study area and two control beach study areas, each 3.1 km in length and consisting of natural beach sands, were established. The entire study area (9.3 km) was monitored for nesting and non-nesting emergences (false crawls) and a tagging program was established. The objectives of the study were to determine the effects of the restoration project on the nesting behavior of adult female turtles, and to develop an understanding of the effects of restored beach sands on the survival of marine turtle eggs and hatchlings. During the 1981 nesting season 2,766 marine turtle emergences were recorded. The nesting success rates (nesting emergences/total emergences x 100) for 1981 on the north control beach and the south control beach were 54% and 51% respectively, whereas the restored beach had a statistically significant lower nesting success of 28%. This reduction of nesting success was attributed to a compact substrate that was markedly less friable than the sands of the control beaches. In 1981, the turtles emerging to nest in the restored area often displayed aberrant digging behavior when they encountered the compact sand. By the following summer of 1982, it was evident that the restored beach substrate was less compact. The nesting success for 1982 in the restored beach (46%) rose to a level equal to that of the control beaches (48% and 46%). A total of 3,144 marine turtle emergences were recorded in the 1982 nesting season. To study the effects of beach restoration on the eggs and hatchlings, nests were marked, left to incubate on the beach, and later excavated to determine hatch success. Hatch data and hatchling emergence data were collected on 30 clutches in each of the three beach sections for both the 1981 and 1982 seasons. No significant difference was found between the hatch percentage for the restored beach and the hatch percentages for the control beaches in either study year. The hatchling emergence data, which would indicate the hatchlings' ability to emerge from the sand, indicate no significant difference between the restored beach and control beaches for 1981 and 1982
Carry-over effects and foraging ground dynamics of a major loggerhead breeding aggregation by Simona A Ceriani( )

1 edition published in 2015 in English and held by 2 WorldCat member libraries worldwide

Human and natural causes of marine turtle clutch and hatchling mortality : and their relationship to hatchling production on an important Florida nesting beach by Blair E Witherington( )

1 edition published in 1986 in English and held by 1 WorldCat member library worldwide

Populations of Western Atlantic loggerheads (Caretta caretta) and Florida green turtles (Chelonia mydas) have been in historical decline. The identification and protection of beaches that are major producers of loggerhead and green turtle hatchlings are vital to the preservation of these species. A study assessing loggerhead and green turtle hatchling production was initiated at a 21 km stretch of beach in south Brevard County, Florida (Melbourne Beach) during the 1985 nesting season. Nesting densities were assessed from a season-long (10 May - 12 September) census in which every nest was counted and identified to species. An analysis of average reproductive success was made from 100 loggerhead and 27 green turtle sample nests. Daily tallies of specific disturbances to nests aided in formulating dimensional descriptions of factors which caused clutch and hatchling mortality. An unprecedented 10,240 loggerhead and 281 green turtle nests were counted within the Melbourne Beach study area in 1985. Approximately 48 and 51 percent of the constituent eggs of loggerhead and green turtle nests resulted in hatchlings that successfully entered the surf. These values are very high compared to data from other nesting beaches. A severe September northeaster storm was the major cause of mortality for clutches of both species. Raccoon predation and the disorientation of hatchlings by beachfront lighting were also significant in limiting reproductive success. Beachfront lighting was also found to significantly deter green turtles from nesting. Predation of nests by raccoons was limited to a small portion of the study area. The rate of hatchling disorientation was found to decrease following the enforcement of a regional ordinance restricting beachfront lights. Management recommendations include: bestowing a special protective status for the Melbourne Beach area; providing efforts to monitor and regulate beach and nearshore activities; initiating specific management practices to mitigate mortality; and enhancing research and public education efforts regarding Melbourne Beach's marine turtles
Movements and feeding ecology of immature green turtles (Chelonia mydas) in Mosquito Lagoon, Florida by Mary T Mendonca( )

1 edition published in 1981 in English and held by 1 WorldCat member library worldwide

The seasonal and diel movements of fourteen immature green turtles (Chelonia mydas) in Mosquito, Lagoon, Florida were monitored using sonic telemetry. The feeding ecology of this turtle population was also studied using dissection and stomach flushing techniques. An attempt was made to relate the movement patterns of the turtles to their feeding habits. The immature green turtles were found to make seemingly random, long distance movements (X km moved/day=7.79) and to remain in deeper waters (X depth=1.63m), apparently not feeding, when water temperatures fell below 19°C. When average water temperatures ranged between 19-25°C, the turtles were found primarily in shallow waters (X depth=1.1m) and demonstrated a decrease in agility (X km moved/day=3.14). At water temperatures above 25°C, the animals became even less agile (2.58 km moved per day) and adopted a home range area that included a "center of activity" and a "home site." A "shuttling" behavior was observed when water temperatures averaged 31°C and higher. In the early mornings, turtles were found feeding on the grass flats. When shallow water temperatures rose above 30°C at midday, the turtles would relocate to deeper water. In late afternoon, they would return to the grass flats for a short period of time. Sea grasses made up 88% of the lagoonal turtle diet, with manatee grass (Syringodium filiforme) alone constituting 77%. No significant difference was found in per cent composition of stomach contents obtained in January via dissection and August via pumping
Modeling and mapping isotopic patterns in the Northwest Atlantic derived from loggerhead sea turtles( )

1 edition published in 2014 in English and held by 1 WorldCat member library worldwide

Seasonal variation in serum testosterone of immature sea turtles in Central Florida by Lawrence K Luepschen( )

1 edition published in 1987 in English and held by 1 WorldCat member library worldwide

A yearlong hormonal study of immature populations of loggerhead turtles (Caretta caretta) and green turtles (Chelonia mydas) inhabiting the Indian River in Central Florida, USA, provided information about the relationship between serum testosterone levels and life history habits. By use of a specific radioimmunoassay, testosterone levels of both species were found to remain constant throughout the year with only a slight increase in the warmer months. Adrenal production of steroids in response to stress does not contribute significantly to overall testosterone levels may be reduced for turtles held in captivity. Testosterone levels indicate that the sex ratios of both species were not significantly different from an expected 1 female : 1 male ratio. Loggerhead and green turtles may begin maturing sexually at a straight line carapace length of 75 cm. Mean testosterone levels of the loggerhead population were greater than those for green turtles in all four seasons, undoubtedly because the loggerheads are older and closer to sexual maturity
The hatching and emergence of loggerhead turtle (Caretta caretta) hatchlings by Richard J Demmer( )

1 edition published in 1981 in English and held by 1 WorldCat member library worldwide

Loggerhead turtle (Caretta caretta) eggs were collected at the time of laying during the summer of 1977 on the beaches of Canaveral National Seashore and the Merritt Island National Wildlife Refuge in Brevard County, Florida. The eggs were placed in sand-lines buckets and maintained at ambient temperature in a house trailer hatchery. After 50 to 55 days of incubation whole or partial clutches were transferred to glass observation containers and covered to a depth of 20 cm. Hatching and emergence behavior were visually observed and activity was timed on an event recorder that was activated by four motion switches placed within or above the clutch. Pipping of the eggs occurred at a mean of 60.5 days after egg deposition. Emergence occurred at a mean of 61.8 hours after pipping and 63.1 days after egg deposition. The hatching and emergence sequence was described. It was concluded that hatching and emergence were socially facilitated. A mechanism for socially facilitated hatching was proposed. Volumetric reduction of the nest behavior before or during pipping was described. Emergence may be inhibited by rising temperatures in the morning and stimulated by falling temperatures within a certain range at night. Social facilitation, in addition to the obvious value of providing a means for reaching the surface, was apparently advantageous to hatchlings as they emerged and raced towards the surf en masse. Under these conditions predators are likely to be efficient than they would be if hatchlings emerged singly
Attentiveness and time budget of a pair of nesting wood storks by E. Scott Clark( )

1 edition published in 1980 in English and held by 1 WorldCat member library worldwide

An instantaneous sampling system was used to quantify nest attentiveness and time budget of a pair of Wood Storks (Mycteria americana) nesting at the Moore Creek colony on Merritt Island National Wildlife Refuge in 1977. The amount of time devoted to various activities during each stage of the 4-month reproductive cycle was examined and differences between stages evaluated. During the incubation period an adult was constantly at the nest site and the birds shared equally in the incubation duties. During the first four weeks of the 8-week pre-flight nestling stage, an adult was with the chicks continuously, although the adults discontinued brooding after the first week. In the latter four weeks of the pre-flight stage and 4-week post-flight stage, the amount of time spent in the colony by the adults diminished until the parents only returned to the colony for several minutes per day to feed the young. The time devoted to incubation, brooding, nest maintenance, and sexual displays declined during the breeding season, while the time spent "loafing" and away from the colony increased. Next defense, chick maintenance, and standing at the nest were maximal during the first half of the pre-flight stage
The reproductive biology of the diamondback terrapin, malaclemys terrapin tequesta by Richard A Seigel( )

1 edition published in 1979 in English and held by 1 WorldCat member library worldwide

The reproductive biology of the Florida east coast terrapin, Malalemys terrapin tequesta was studied during 1977-1978 at the Merritt Island National Wildlife Refuge, Brevard County, Florida. Mating occurred in small canals and ditches during late march and April. Terrapins exhibited a poorly developed courtship behavior system: this was attributed to the relative isolation of the species due to its brackish water habitat. Nesting occurred on dike roads, rather than on sand dunes as reported for other races of Malaclemys. Air temperature was the most important factor controlling nesting activity. One to three clutches were laid each year. Malaclemys appeared to exhibit a clinal variation in clutch size between northern and southern populations. Reduced clutch size in the south is explained by a relative increase in egg and hatchling size, possible resulting in greater survivorship of offspring in southern populations. Adult females nesting on dike roads are subject to severe predation from raccoons
History, population structure and ecology of marine turtles of the Indian River Lagoon System by Llewellyn M Ehrhart( Book )

1 edition published in 1980 in English and held by 1 WorldCat member library worldwide

Nest-building behavior and food habits of the rice rat, Orysomys palustris natator, from Merritt Island, Brevard County, Florida by Margaret Hart Harrison( )

1 edition published in 1974 in English and held by 1 WorldCat member library worldwide

Factors affecting the hatching success of loggerhead sea turtle eggs : (Caretta caretta caretta) by M. Angela McGehee( )

1 edition published in 1979 in English and held by 1 WorldCat member library worldwide

Clutches of eggs wore collected from nesting loggerhead sea turtles (Caretta caretta caretta) on Merritt Island, Florida, during June - August 1977. Of these, 46 clutches were selected for experimentation to determine the extent to which certain factors affect hatching success. Twelve clutches were divided into subsamples which were incubated in sand maintained at 0, 25, 50, 75, and 100% moisture. Another twelve clutches were divided into subsamples and incubated in sand kept moist with the following percentages of seawater: 0 (distilled water), 25, 50, 75, and 100%; subsamples from four other clutches were subjected to the effects of one tidal inundation. Eggs from four of the clutches used in the moisture and salinity experiments were monitored for changes in size. Fifteen clutches were divided into subsamples which were kept in incubators maintained at 20, 24, 27, 30, 32, 35, and 38°C; subsamples from seven of these clutches were moved from unfavorable to optimal temperatures to study their ability to recover from stress. Three clutches were selected for an experiment to determine the effects of handling on hatching success; the following year, another five clutches were used for similar studies. Some of the hatchling turtles produced in this project were abnormal, and these were discussed in depth. From the experiments, it was determined that 25% moisture, 0-25% seawater, and 27°C produced the maximum percent hatch. The effects of handling on hatching success depended variably on the time and manner of handling. The optimum values indicated in the experiments closely approximated values for moisture, salinity, and temperature obtained from natural turtle nests on the beach
Preliminary investigation of papillomatosis in green turtles : phase I - frequency and effects on turtles in the wild and in captivitiy by Llewellyn M Ehrhart( Book )

1 edition published in 1986 in English and held by 1 WorldCat member library worldwide

The reproductive biology of sternotherus minor minor : (reptilia : testudines : kinosternidae) from the southern part of its range in Central Florida by Cory Randal Etchberger( )

1 edition published in 1984 in English and held by 1 WorldCat member library worldwide

Variation in chelonian reproductive patterns is well documented. Previous studies of loggerhead musk turtles (Sternotherus minor) reproduction have not attempted to control for variation in latitude, local population differences, and seasonal variation. The present study attempts to control for these variables by collecting turtles from one population for one reproductive season. The reproductive pattern of S. minor at the southern limit of its range (Central Florida) is compared to those of S. minor studied elsewhere. Both male and female musk turtles mature after five to six years and at approximately 60mm plastron length. No sexual dimorphism in overall body size is evident. There is a significant relationship between testis mass and male body size. Spermatogenesis begins in June as testes begin to enlarge. A peak in the testicular cycle is observed in August and September followed by testicular regression from October through January. A germinal quiescent phase is evident from February through April. Vitellogenesis in females begins in mid-September and the first clutch is laid in late October. Ovipositions continue until mid-June when follicular regression begins. A brief but distinct ovarian quiescent period occurs in August. Mean clutch size is 3.0 (range= 1-5). Clutch size and clutch mass were significantly correlated with body size. Egg length is not significantly correlated with clutch size or plastron length. Four clutches per year are common and some females probably produce five. Reproductive potential and individual reproductive effort are both correlated with body size. Testicular activity peaks six months after a peak in the ovarian cycle. Similarities with other studies of Sternotherus minor include: timing of the reproductive cycles, mean female size, and size and age at maturity. Mean clutch size in Central Florida is significantly larger than elsewhere. This difference is explained by the fact that more females produce three and four eggs. While similarities and differences in reproductive characteristics do exist between Central Florida S. minor and more northern populations, it is clear that those similarities and differences must be interpreted with respect to the methods of data collection used. Annual reproductive potential is enhanced in the Central Florida population. This is explained by greater resource availability which is translated into a greater reproductive output
A comparative study of the feeding ecology of chelonia mydas (green turtle) and the incidental ingestion of prorocentrum spp by Karen Gayle Holloway-Adkins( )

1 edition published in 2001 in English and held by 1 WorldCat member library worldwide

The diets of green turtles from five dissimilar aggregations of juvenile C. mydas on the East Coast of Florida were analyzed. C. mydas were captured by tangle net from four of the study sites and a dietary sample was collected by an esophageal flushing technique. The gut content of stranded individuals was collected for the fifth site. The vegetation in these study areas differs in varying degrees of abundance and diversity. Analysis of the samples revealed the alga types preferred by green turtles from each population and provided the basis for examination of similarities and differences in their diets. Large numbers of the juvenile C. mydas worldwide are infected with a disease called Fibropapillomatosis (FP). The herpes-type virus that appears to cause the disease manifests as tumors normally on the fleshy parts of the body. The placement and size of the tumors can eventually impede the green turtle's ability to swim and forage. Severe conditions of the disease lead to death either by starvation or the inability to evade predators. While the herpesvirus initiates FP, there are other environmental cofactors that may play a role in promoting the disease. Some toxic microalgae (dinoflagellates) of the genus Prorocentrum produces a known tumor promoter called okadaic acid. The acid has been shown to promote cutaneous tumors in laboratory mice. These Prorocentrum species live primarily as epiphytes, forming a mucilaginous attachment to seagrasses and macroalgae. Chelonia mydas may be consuming the toxic microalgae when they forage on vegetation. Samples of available vegetation at each study area were collected and examined to determine if C. mydas were potentially consuming Prorocentrum. Prorocentrum were quantified for diet items by counting the number of cells per wet weight of macroalgae. In most cases, the diet analysis and microalgae quantification results showed an association between the consumption of substrates utilized by Prorocentrum spp and a high prevalence of FP in that population
Geomagnetic map used in sea-turtle navigation by Kenneth J Lohmann( )

1 edition published in 2004 in English and held by 0 WorldCat member libraries worldwide

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