Biology and Pathogenesis of the Coccidium Eimeria funduli Infecting Killifishes

Epizootics of Eimeria funduli involved estuarine killifishes (Fundulus grandis, F. pulvereus, F. similis, and F. heteroclitus) in Mississippi, Alabama, and Virginia. All of more than 500 specimens examined of F. grandis from Mississippi during 1977 through 1979 had infections, regardless of age, sex, or season collected. Oocysts occurred primarily in the liver and pancreas, replacing up to 85% of both those organs. Infrequent sites of infection were fatty tissue of the body cavity, ovary, intestine, and caudal peduncle. Living fish did not discharge oocysts. Eimeria funduli is the first known eimerian to require a second host. To complete the life cycle, an infective stage in the grass shrimp Palaemonetes pugio had to be eaten. In 6-mo-old killifish reared in the laboratory at 24 C, young schizonts were first observed in hepatic and pancreatic cells 5 days post feeding, followed by first generation merozoites by day 10, differentiation of sexual stages during days 15 to 20, fertilization between days 19 and 26, sporoblasts from days 25 to 30, and sporozoites about day 60. Unique sporopodia developed on sporocysts by day 35 when still unsporulated. Temperatures of 7 to 10 C irreversibly halted schizogony. Both schizogony and sporogony progressed slower as age of host increased. When infective shrimp in doses ranging from 1 to 10% of a fish's body weight were eaten, the level of intensity of resulting infections did not differ significantly. Pathogenesis followed a specific sequence, with the host response apparently unable to contend with extensive infections as seen typically in nature and in our experiments. Premunition was indicated. When administered Monensin® orally, infected fish exhibited a reduction in oocysts by 50 to 70% within 20 days as compared with untreated fish. Furthermore, infected killifish maintained exclusively on a diet of TetraMin® for 3 mo completely lost their infections.

Review of The Biology of Freshwater Wetlands: Biology of Habitats by Arnold G. van der Valko

Wetland ecology is a relatively new field that developed from an initial interest in a few direct benefits that wetlands provide to society. Consequently, much early scientific work was stimulated by economic returns from specific wetland services, such as production of peat and provision of habitat for economically valuable wildlife (e.g., waterfowl and furbearers). Over time, societal interest in wetlands broadened, and these unique habitats are now valued for many additional services, including some that bear non market value. Common examples include carbon sequestration, flood reduction, water purification, and aesthetics. The increased recognition of the importance of wetlands has generated a diversity of job opportunities in wetland ecology and management. Despite the increased knowledge base and enhanced job market, I am not aware of any institutions that offer specialty degrees in this new discipline. Indeed, relatively few institutions offer specific wetland ecology classes, with Arnold G. van der Valk and a few of his peers at other universities being notable exceptions.

Introduction [to Biology of the Acanthocephala]

Introduction to Biology of the Acanthocephala, edited by D.W.T. Crompton and Brent B. Nickol; Cambridge University Press, 1985.

Epizootiology: [Chapter 9 in Biology of the Acanthocephala]

In practice, epizootiology deals with how parasites spread through host populations, how rapidly the spread occurs and whether or not epizootics result. Prevalence, incidence, factors that permit establishment of infection, host response to infection, parasite fecundity and methods of transfer are, therefore, aspects of epizootiology. Indeed, most aspects of a parasite could be related in sorne way to epizootiology, but many of these topics are best considered in other contexts. General patterns of transmission, adaptations that facilitate transmission, establishment of infection and occurrence of epizootics are discussed in this chapter. When life cycles are unknown, little progress can be made in understanding the epizootiological aspects of any group of parasites. At the time Meyer's monograph was completed (1933), intermediate hosts were known for only 17 species of Acanthocephala, and existing descriptions are not sufficient to permit identification of two of those. Laboratory infections of intermediate hosts had apparently been produced for only two species. Study at that time was primarily devoted to species descriptions, host and geographical distribution, structure and ontogeny. Little or nothing was known about adaptations that promote transmission and the concept of paratenic hosts was unclear. In spite of the paucity of information, Meyer (1932) summarized pathways of transmission among principal groups of hosts, visualized the relationships among life cycle patterns for the major groups of Acanthocephala, and devised models for the hypothetical origin of terrestrial life cycles from aquatic ones. Nevertheless, most of our knowledge regarding epizootiology has been recently acquired.

Biology and Impacts of Pacific Island Invasive Species. 5. Eleutherodactylus coqui, the Coqui Frog (Anura: Leptodactylidae)

The nocturnal, terrestrial frog Eleutherodactylus coqui, known as the Coqui, is endemic to Puerto Rico and was accidentally introduced to Hawai‘i via nursery plants in the late 1980s. Over the past two decades E. coqui has spread to the four main Hawaiian Islands, and a major campaign was launched to eliminate and control it. One of the primary reasons this frog has received attention is its loud mating call (85–90 dB at 0.5 m). Many homeowners do not want the frogs on their property, and their presence has influenced housing prices. In addition, E. coqui has indirectly impacted the floriculture industry because customers are reticent to purchase products potentially infested with frogs. Eleutherodactylus coqui attains extremely high densities in Hawai‘i, up to 91,000 frogs ha-1, and can reproduce year-round, once every 1–2 months, and become reproductive around 8–9 months. Although the Coqui has been hypothesized to potentially compete with native insectivores, the most obvious potential ecological impact of the invasion is predation on invertebrate populations and disruption of associated ecosystem processes. Multiple forms of control have been attempted in Hawai‘i with varying success. The most successful control available at this time is citric acid. Currently, the frog is established throughout the island of Hawai‘i but may soon be eliminated on the other Hawaiian Islands via control efforts. Eradication is deemed no longer possible on the island of Hawai‘i.

Niche Specialization and Conservation Biology of Cicindela nevadica lincolniana

As with many organisms across the globe, Cicindela nevadica lincolniana is threatened with extinction. Understanding ecological factors that contribute to extinction vulnerability and what methods aid in the recovery of those species is essential in developing successful conservation programs. Here we examine behavioral mechanisms for niche partitioning along with improving techniques for captive rearing protocol and increasing public awareness about the conservation of this local insect. Ovipositional selectivity was examined for Cicindela nevadica lincolniana, Cicindela circumpicta, Cicindela togata, Cicindela punctulata, and Cicindela fulgida. Models reflect that these species of co-occurring tiger beetles select different ranges of salinity in which to oviposit thereby reducing the potential for interspecific competition. In a second study, thermoregulatory niche partitioning was examined for the same complex of tiger beetle species. Time spent in the sun, on different substrates, and engaging in various behaviors associated with thermoregulation were significantly different during different parts of the day and between species. I continued along a previous line of study to develop a viable captive rearing program. So far fourteen adult Cicindela nevadica lincolniana have been successfully reared in captivity. Overwintering mortality has been determined as a key factor in the mortality of this species in captivity. Finally, I examined the potential for using the visual arts to promote the conservation of Cicindela nevadica lincolniana and associated saline wetlands. The results from surveys conducted at the exhibit suggest that art exhibits can have a strong positive impact on members of the community.

Redox Biology Center Mini-Symposium

Good morning. It's my very great pleasure to welcome you to this third annual mini-symposium in Redox Biology.