Stephen G Dunbar

Stephen G Dunbar
Loma Linda University · Department of Earth and Biological Sciences

PhD

About

76
Publications
13,450
Reads
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555
Citations
Introduction
Current research interests are in marine invertebrate physiology and ecology, and sea turtle ecology and conservation.
Additional affiliations
August 2015 - present
Loma Linda University
Position
  • Professor
July 2009 - July 2015
Loma Linda University
Position
  • Associate Professor, Graduate Biology Program Director, Director of the Marine Research Group, President/Founder of ProTECTOR
January 1998 - May 2002
Central Queensland University
Position
  • Research Assistant

Publications

Publications (76)
Article
An unusual fossil in situ paguroid hermit crab is here reported from the Oligocene Pysht Formation, Washington (USA). Paguroid specimens preserved within their host gastropod shells are rare in the fossil record. Only a few reports of in situ paguroid hermit crabs preserved within their host gastropod shells have been reported from the Cenozoic.
Article
Full-text available
Very few studies have been undertaken on water quality from mobile homes, with most information coming from press and policy reports suggesting that people living in mobile homes in the US have poor water quality. Our goal was to evaluate resident exposure to microbes at the point of use of tap water sourced from the Oasis Mobile Homes Park (OMHP),...
Article
Marine protected areas (MPAs) have been established to decrease the negative impacts of human activities on important marine habitats. Several sea turtle species reside within MPAs; however, analyses of habitat suitability for sea turtles within many MPAs is typically lacking. Habitat modeling and species mapping have become essential tools in dete...
Article
Full-text available
Anthropogenic disturbances affect the health of coral reefs worldwide and may also impact hawksbill (Eretmochelys imbricata) foraging areas, potentially decreasing sponge numbers, while increasing macroalgae. Few studies have been conducted to understand energy content of hawksbill prey. We investigated observed (Geodia neptuni and Kallymenia limmi...
Article
Although heavy metal concentrations naturally vary in the environment, anthropogenic sources of heavy metals can mask and override such fluctuations. Indicator species can be used to determine environmental concentrations of certain metals and evaluate the impacts of metals from associated anthropogenic sources. We sought to determine if the hermit...
Chapter
After a brief introduction on the topic of photo identification (PID), the chapter leads into new insights and advances in the recently developed use of PID in sea turtle research. This chapter focuses on the application of PID in three case studies from around the world. The first case study centers on the French territory of Reunion Island and th...
Article
Full-text available
Drinking water quality from sources other than tap water is increasingly becoming a source of concern in many communities. Communities in the Eastern Coachella Valley (ECV), Riverside County, California, USA have raised concerns regarding bulk drinking water from water vending machines (WVMs) found in public vendors. To address concerns, we conduct...
Article
Photo identification (PID) in animal studies has been a widely used method for identifying individuals of many species based on unique natural markings and patterns. The use of PID has facilitated investigations in which residency, home ranges, and growth rates have been assessed. However, many PID studies in the past have relied heavily on manual...
Article
Full-text available
The countless tranquil beaches of the Caribbean, with their gently lapping waves and fringing palm trees, give the feeling of permanence. Although you could be excused for thinking that these ecosystems—and their sea turtle inhabitants—have remained largely untouched for millennia, this is far from the truth. Sea turtles have provided the people of...
Article
Abstract: An unusual fossil in situ paguroid hermit crab is here reported from the Oligocene Pysht Formation, Washington (USA). Paguroid specimens preserved within their host gastropod shells are rare in the fossil record. Only a few reports of in situ paguroid hermit crabs preserved within their host gastropod shells have been reported from the Ce...
Article
Full-text available
We describe historic and present occurrences as well as anecdotal reports of five species of sea turtles in the Gulf of Fonseca, Honduras. Additionally, we go on to provide a descriptive context about confusion between species by local community members, occurrence of hybrid turtles, and nesting sites for the region. Our descriptions provide a benc...
Article
Animals are tracked using a wide range of methods. Some researchers track animals by manually recording global positioning system locations while others combine manually recorded locations with sophisticated mapping software. Individuals of the public regularly come in contact with animals and, as citizen-scientists, may represent a relatively cons...
Article
Increased sedimentation in intertidal areas may stem from anthropogenic sources such as coastal development and natural processes, including discharges by rivers, landslides, and floods. Furthermore, global climate change could eventually lead to environmental hypoxia altering the composition of intertidal communities when hypoxia events surpass th...
Article
Full-text available
Cyprinid herpesvirus 3 (CyHV-3) or koi herpesvirus (KHV) is a virulent viral infection in common carp and koi. The disease has caused global epizootic and economic loss in fish aquaculture and in the wild. Clinacanthus nutans (Burm. f.) Lindau is a well-known medicinal plant used in Thai traditional medicine. Virucidal effects of the plant extract...
Article
Full-text available
The raccoon, Procyon lotor, is the definitive host for raccoon roundworm (Baylisascaris procyonis), which causes a dangerous neurological disease known as larva migrans encephalopathy in intermediate hosts. As omnivores, raccoons rely on a variety of food items. Parasitized animals may exhibit altered eating habits and diets, and may undergo geneti...
Article
Full-text available
We subjected the intertidal hermit crab, Pagurus samuelis (Stimpson, 1857), to various treatments to determine physiological responses of this species to the environmental stress of burial. Hermit crabs were buried with 6 cm of sediment and excavated at 2 h intervals up to a maximum of 12 h. Duration of burial and state (alive or dead) of the crab...
Technical Report
Full-text available
This report represents the ongoing work of the Protective Turtle Ecology Center for Training, Outreach, and Research, Inc. (ProTECTOR Inc.) in Honduras. The report covers activities of ProTECTOR Inc. during the 2015 and 2016 calendar years, and is provided in partial fulfillment of the research permit agreements provided to ProTECTOR Inc. by DIGEPE...
Presentation
Full-text available
Recent studies indicate that recreational diving may cause unintended behavioral changes in marine macrofauna. The hawksbill sea turtle (Eretmochelys imbricata) is a critically endangered species encountered pantropically by recreational divers in marine protected areas (MPAs). No other studies to date however, have examined the impacts of recreati...
Presentation
Full-text available
Conference poster describing new methods for sea turtle photo identification
Article
Full-text available
Sedimentation and increasing temperature caused by human disturbances and global climate change are additive in their effects on coastal areas. To assess their influence on intertidal organisms, we studied the hermit crab, Pagurus samuelis, under acute temperature changes and shallow burial conditions. We applied three temperatures (5℃, 20℃, and 30...
Article
Full-text available
Somatic growth dynamics are an integrated response to environmental conditions. Hawksbill sea turtles (Eretmochelys imbricata) are long-lived, major consumers in coral reef habitats that move over broad geographic areas (hundreds to thousands of kilometers). We evaluated spatio-temporal effects on hawksbill growth dynamics over a 33-yr period and 2...
Article
The hawksbill sea turtle (Eretmochelys imbricata) is a critically endangered species encountered by recreational divers in marine protected areas (MPAs) circumtropically. Few studies, however, have examined the impacts of recreational diving on hawksbill behaviours. In 2014, we collected turtle sightings surveys and dive logs from 14 dive operation...
Poster
Full-text available
Recent studies indicate that recreational diving may cause unintended behavioral changes in marine macrofauna. The hawksbill sea turtle (Eretmochelys imbricata) is a critically endangered species encountered by recreational divers in marine protected areas (MPAs) circumtropically. Few studies, however, have examined the impacts of recreational divi...
Technical Report
Full-text available
This report represents the ongoing work of the Protective Turtle Ecology Center for Training, Outreach, and Research, Inc. (ProTECTOR Inc.) in Honduras during the 2014 season and is provided in partial fulfillment of research agreements with the Roatán Marine Park.
Article
Full-text available
Harmful bloom-forming cyanobacteria (CyanoHABs) and associated toxins are increasingly prevalent world-wide. We conducted a screening-level study to determine if cyanobacteria and associated cyanotoxins were present in Southern California coastal lakes, ponds, and seasonally tidal lagoons. We evaluated waterbody nutrient status and physiochemical p...
Technical Report
Full-text available
This report represents the ongoing work of the Protective Turtle Ecology Center for Training, Outreach, and Research, Inc. (ProTECTOR) in Honduras. The report covers activities of ProTECTOR during the 2013 and 2014 calendar years, and is provided in partial fulfillment of the research permit agreements provided to ProTECTOR by DIGEPESCA. All publis...
Poster
Full-text available
The hawksbill sea turtle (Eretmochelys imbricata) can be found in the Atlantic, Pacific and Indian Oceans. As with other sea turtles species, hawksbills have a cluster of scales on the dorsal and lateral surfaces of the head that form unique scale patterns. Following a previous study using Interactive Individual Identification System (I3S) Spot, we...
Poster
Full-text available
Recreational diving is a form of ecotourism that is traditionally viewed as an ecologically sustainable activity prompting increased awareness for the marine environment. Still, recent studies indicate that recreational diving may cause increased spatio-temporal variability within coral ecosystems and unintended behavioral changes in marine macrofa...
Poster
Full-text available
The Bay Islands of Honduras consist of three different islands, one of which is the island of Roatán on which the Roatán Marine Park (RMP), a marine protected area, is located at the west end. The RMP has only recently become an important area for sea turtle populations. The marine park is patrolled daily by park rangers to prevent illegal fishing...
Poster
Full-text available
The Protective Turtle Ecology Center for Training, Outreach, and Research, Inc. (ProTECTOR) works to increase the conservation of, and research on sea turtles in the country of Honduras. Efforts were made this summer to record the sightings of sea turtles in Roatán, specifically in the area of West End and the Roatán Marine Park (RMP). We worked in...
Article
Full-text available
Advancements in digital photography have facilitated the use of photo-ID to track individual animals, making this technique of great value for conservation biology. However, the time required to manually match new photographs to those stored in a database is proportional to the size of the database. Therefore, there is need for investigating the po...
Article
Full-text available
Raccoon roundworm is a leading cause of a neurological disease known as larva migrans encephalopathy in vertebrates. We determined that roundworm prevalence is significantly lower in Beavercreek Township than other townships surveyed, and that mean patch size and proportion of landscape modified by urbanization or by agriculture are good predictors...
Article
We investigated the biochemical profile of regenerated venom of the scorpion Parabuthus transvaalicus in relation to its metabolic cost and toxicity. Using a closed-system respirometer, we compared oxygen consumption between milked and unmilked scorpions to determine the metabolic costs associated with the first 192 h of subsequent venom synthesis....
Article
Cyanobacteria often dominate eutrophic lakes, outcompeting green algae that are required by fish and zooplankton. This study was undertaken to ascertain the impact of the cyanobacterium, Microcystis, on algal biodiversity. Under laboratory conditions, we found that the presence of Microcystis decreased phyla richness by 58%, phyla evenness by 47%,...
Article
Full-text available
Despite the recognition of the historical importance of hawksbills in the Caribbean region of Honduras, prior sea turtle research in the area has been extremely limited, and little is known about hawksbill turtle (Eretmochelys imbricata) ecology from this region. We tracked 6 juvenile hawksbills (28.7–35.6 cm, straight carapace length [SCL]) with r...
Article
Shell and food acquisition behaviors of the hermit crab, Pagurus samuelis, were examined in response to cues of shell and food availability. Tactile, visual, and chemical cues were presented in a factorial manner, and time was measured between initial contact and either inhabitation of a shell or initiation of feeding. We considered the time differ...
Article
The intertidal hermit crab, Pagurus samuelis, was subjected to various treatments analyzed to determine behavioral responses to the ecological stress of burial. Hermit crabs were buried at varying depths (2, 4, and 6 cm), and in two orientations (shell aperture up and aperture down). Hermit crab weight, shell weight, shell shape, aperture orientati...
Article
The biochemistry of fatty acids (FA) can be affected by a number of factors, including environmental temperature, which may affect the way FAs are physiologically metabolized. In this study, we investigated FAs in Pachygrapsus crassipes, in relation to environmental temperatures in southern California. Although there was a trend toward differences...
Article
Full-text available
Both the need for shelter and the need for food can be motivations that alter animal behaviour. We tested the hypothesis that the hermit crab, Pagurus samuelis, deprived of food, shells, or both will respond differently from control hermit crabs when presented with food and shells concurrently. We measured the number of contacts made with both food...
Article
Full-text available
In the Drowned Cayes area of Belize, manatees (Trichechus manatus manatus) are commonly observed resting in depressions in the substrate, locally referred to as manatee resting holes. To understand why manatees prefer locations with resting holes, the physical and environmental attributes of the depressions were characterized and diurnal and noctur...
Article
One of the proposed ecological functions of sleep is to conserve energy. The majority of studies that support this theory have been done on endothermic animals whose body temperatures drop during sleep due to the reduced neurological control of thermoregulation. In the present study, we examined typical temperatures to which the Desert Iguana, Dips...
Conference Paper
Full-text available
The current investigation both identified fatty acids (FAs) as well as quantified total and specific FA concentrations in the striped shore crab, Pachygrapsus crassipes, in relation to seasonal temperatures and sex. We examined changes in FA abundance and FA saturation levels (saturated, monounsaturated, polyunsaturated) over seasons and between se...
Article
Scorpion venom has many components, but is mainly made up of water, salts, small molecules, peptides, and proteins. One can reasonably assume that the production and storage of this complex secretion is an expensive metabolic investment. However, to date, no study has addressed the costs associated with the regeneration of venom by scorpions. Using...
Technical Report
Full-text available
Throughout the Caribbean region, the spiny lobster, Panulirus argus, is a species of great commercial importance. Between 2000 and 2003, over 77,000 metric tonnes of lobster were exported from the Caribbean, indicating the potential economic value of the species for developing nations in the region. In the Bay Islands of Honduras, the harvest of P....
Article
The vision of the School of Science and Technology (SST) at Loma Linda University (LLU) is to develop an interdisciplinary approach to doing science that bridges the social, biological, earth, and health sciences. It will provide opportunities for undergraduate, graduate, and professional students to apply new tools and concepts to the promotion of...
Conference Paper
Morphometrics, including shield length, wet weight, sex, shell species and shell weight, were collected on Pagurus samuelis collected at Monterey Bay, California in July 2003. Empty gastropod shells and individuals of each snail species were counted at each site to give a profile of relative abundances for those shells potentially available to herm...
Article
The tropical intertidal hermit crabs Clibanarius taeniatus and Clibanarius virescens were examined for differences in survival and physiological responses in low salinity. We found that C. taeniatus survived better in dilute seawater than C. virescens and that these species did not differ in their abilities to regulate haemolymph osmolarity, ionic...
Article
Full-text available
Dunbar, S.G., Coates, M., and Kay, A. 2003. Marine hermit crabs as indicators of freshwater inundation on tropical shores. In: Lemaitre, R., and Tudge, C.C. (eds), Biology of the Anomura. Proceedings of a symposium at the Fifth International Crustacean Congress, Melbourne, Australia, 9-13 July 2001. Memoirs of Museum Victoria 60(1): 27-34. The mari...