Browsing by Subject "nursery"

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Open Access
Nursery Areas of the Giant Manta Ray and a Road Map Towards Better Protection of the Species
(2022-04-19) Ives, Nora
Maintaining our oceans biodiversity is imperative to creating a sustainable future for our blue planet. Many marine species, including sharks, rays, and sea turtles, use specific areas as nursery habitat where juveniles of the species live until they reach maturity. By identifying and prioritizing the management of nurseries, we can protect species of conservation concern at the most vulnerable phase of their life history. This project uses a literature review to identify environmental attributes of nursery habitat for the globally endangered giant manta ray (Mobula birostris). This research was used to create an ecological envelope of potential nursery habitat for the species in the Gulf of Mexico and the surrounding region. The resulting spatial analysis reveals gaps in our understanding of giant manta ray habitat requirements and informs recommendations for better management of the species in the Gulf of Mexico region.
Open Access
Occurrence, Distribution and Reproductive Status of Female Bottlenose Dolphins (Tursiops truncatus) in Roanoke Sound, NC
(2020-04-23) Reibel, Waverly
I examined the spatial distribution of bottlenose dolphin (Tursiops truncatus) nursery groups in Roanoke Sound, NC, to gain insight into how environmental parameters affect site fidelity, and to determine whether habitat use patterns change based on the reproductive state of females. For mature females, I compiled information on interbirth intervals and length of calf dependency to obtain a more comprehensive picture of the ecology and life history of this age-sex class of estuarine dolphins. I analyzed photo-identification data from Roanoke Sound to compare the location and extent of kernel density estimates of home ranges for nursery groups, non-nursery groups and individual females. Many nursery groups are observed in this area during spring and summer, leading to the hypothesis that Roanoke Sound is an important nursery habitat. The importance of this area to lactating females may be attributable to its relatively shallow depth and abundant seagrass beds, which provide protection and a relatively plentiful supply of prey. In Roanoke Sound, nursery groups (n = 170) were significantly (p < 0.00001) larger than non-nursery groups (n = 68) with a mean of 12 individuals per sighting, while non-nursery groups averaged 4 individuals. Nursery groups and non-nursery groups had a high overlap percentage between ranging patterns, with home ranges overlapping 88%. This demonstrates that there is no specific “nursery area” within the Roanoke Sound, but coupled with the high numbers of large nursery groups sighted during the summer, the entire site itself may be of importance to these females. Four focal females had a mean interbirth interval of 7.5 years, and a mean length of calf dependency of 4.75 years. The females exhibited individual variation in ranging patterns, with habitat use overlap between nursery and non-nursery areas ranging from 11-79%. These females may be choosing areas based on their needs (and those of their calves), either for energetic purposes or protection. Documentation of nursery habitat can aid protection of these important areas through implementation of measures such as safe boating zones and increased water quality monitoring, as well as assist in the development of educational materials.