Stephen G. Dunbar

Home Range and Foraging Ecology of Juvenile Hawksbill Sea Turtles (Eretmochelys imbricata) on Inshore Reefs of Honduras

Abstract 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 radiotelemetry off the coast of Roatán in the Bay Islands of Honduras, conducted habitat assessments at 14 sites, and examined the diet of 5 juvenile hawksbills (19.8–49.7 cm, SCL) using gastric (n  =  4) and fecal (n  =  1) samples. Home ranges of all 6 turtles were small, with 100% minimum convex polygons from 0.15 to 0.55 km2, and a 50% fixed kernel density for all animals pooled of 5.46 km2. The habitat assessment showed that common prey items in hawksbill diets were abundant in areas where juvenile hawksbills were resident and in nonresident areas, with sponges (Chondrilla sp., Geodia sp.) and octocorals (Pseudopterogorgia sp.) being most prevalent. We found sponge to be the primary component in the diet, comprising 59% of total ingesta. The most prevalent sponge species in the diet samples were Melophlus ruber and Chondrilla caribensis. Although C. caribensis is a common constituent of hawksbill diets, the current study provides the first report of M. ruber as a component of hawksbill diets. Home ranges of juvenile hawksbills in the Port Royal region of Roatán are small (< 1 km2), and their primary dietary component is the sponge M. ruber. Conservation efforts on Roatán should be established in the Port Royal region, and should include protection of dietary items and turtles.

Influence of motivation on behaviour in the hermit crab, Pagurus samuelis

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 and shells, and time elapsed until hermit crabs either began feeding or inserted into shells. We interpreted making few contacts and initiating behaviour quickly to be an indication of short decision time and high motivation; whereas, making many contacts and having long initiation time indicated a long decision time and low motivation to acquire resources. Control (C) hermit crabs made 72 % more contacts with food and 53% more contacts with shells than shell-less (S) crabs. Control hermit crabs also made 34 % more contacts with food and 35 % more contacts with shells than starved and shell-less (StS) hermit crabs. This suggests that S hermit crabs were more motivated to acquire shells than C crabs. In addition, StS hermit crabs chose to insert into provided shells, while hermit crabs remaining in their shells chose to feed. Results indicate that being shell-less is a stronger motivation than being starved, such that finding shelter takes priority over finding food when both are needed. In rocky intertidal environments, resources such as food and shells are likely to be ephemeral. Hermit crabs that are motivated to make appropriate decisions to acquire specific resources may have a distinct advantage over those that are distracted by numerous objects in their environment.

Impacts of Recreational Diving on Hawksbill Sea Turtle (Eretmochelys imbricata) Behaviour in a Marine Protected Area

ABSTRACT 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 operations, and conducted in-water observations of 61 juvenile hawksbill turtles in Roatán, Honduras, to determine if differences in dive site use and diver behaviours affected sea turtle behaviours in the Roatán Marine Park. Sightings distributions did not vary with diving pressure during an 82-day study period. We found the amount of time turtles spent eating, investigating and breathing decreased when approached by divers. Our results suggest diver interactions may negatively impact sea turtle behaviours, however it is unknown if recreational diving has a cumulative effect on turtles over time. We recommend that MPA managers should implement monitoring programmes that assess the impacts of tourism on natural resources. We have established monitoring of hawksbills as representatives of the marine habitat in an MPA, which has the potential to be heavily impacted by dive tourism, and provide recommendations for continued monitoring of the resource.

Predicting Baylisascaris procyonis Roundworm Prevalence, Presence and Abundance in Raccoons (Procyon lotor) of Southwestern Ohio Using Landscape Features

Graphical abstract Raccoon roundworm (Baylisascaris procyonis) prevalence varies between adjacent townships in Clark and Greene Counties, Ohio along with landscape features.

Temporal Fluctuations of Fatty Acids in Pachygrapsus crassipes from Southern California

Abstract 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 in FA abundances in the hepatopancreas of females compared with those found in the hepatopancreas of males, these differences were not significant through most of the year. The sampling month influenced changes in the abundances of both individual FAs (identities) and FA saturation categories (saturated  =  SAFA, monounsaturated  =  MUFA, polyunsaturated  =  PUFA). The abundances of palmitoleic acid, palmitic acid, and docosahexaenoic acid were found to fluctuate significantly over time, although this fluctuation did not appear to be directly influenced by temperature since an increase in FA abundance between February and April preceded an increase in temperature. In all months except for June, PUFAs dominated the FA profile. Changes in FAs may be an acclimatory mechanism used by P. crassipes to take advantage of specific biochemical properties of FAs. We conclude that, while temperature may affect FA abundance and composition, other underlying factors, such as changes in day length, food availability, molting, mating and reproduction, may also influence FA abundances in P. crassipes from southern California.