The home range can be further understood by examining: (1) environmental factors that are responsible for its selection, and (2) habitat use. Green turtle (Chelonia mydas) home ranges are characterized by their food abundance, distribution, and quality. The shallow water habitats of The Bahamas are important foraging sites for juvenile green turtle. The goal of this study was to determine how turtles use their home range at a tidal foraging site. I tracked turtle home range using acoustic telemetry. I conducted esophageal lavage on tracked turtles and mapped the vegetation coverage. Turtle home ranges were small, and often overlapping areas (mean ± SD= 0.64 ± 0.24 km2). Turtles consumed primarily seagrass (Thalassia testudinum), which was concentrated inside the tidal creek. This study documented the smallest recorded home ranges of juvenile green turtles and examines the combination of the effects of tide, temperature, and vegetation on green turtle home range.
Green turtles living in coastal foraging areas often occupy distinct home ranges within which they visit resting and foraging sites. Knowledge about the size of home ranges and movement patterns within these areas is important for sea turtle conservation. However, few data are available for the wider Caribbean. This study measured the movement pattern of five juvenile green sea turtles in Brewers Bay, St. Thomas, in the US Virgin Islands. Each turtle was fitted with a V13 acoustic transmitter and tracked from 90 to 214 days. Turtles were tracked with a fixed array of 30 acoustic receiving stations placed ~200-260 meters apart throughout Brewers Bay. Minimum convex polygon (MCP) and kernel density estimator (KDE) techniques were used to measure home range size. Home ranges were split into days vs. night times and compared by using utilization distributions (UD). Habitat classification was done in areas of high turtle activity and overlapped with home ranges. A general linear model was used to explore the relationship between the home range size (95% UD), core area size (50% UD), and potential predictors: mass. Average KDE day home range size was 63.3 Ha and average day core area was 6.9 Ha. Average KDE night home range size was 35.9 Ha and average night core area was 5.1 Ha. All five incremental area plots became asymptotic, indicating that the home range estimates are robust. There was a statistically significant relationship between core area size and predictor variable (P-value= 0.002; mass). Tracking results showed that all five turtles remained in Brewers Bay for 98% of the tracking duration. During the day turtles were located in seagrass beds and at night they moved to resting areas associated with natural and artificial coral reefs. Core areas for foraging overlapped with seagrass beds dominated by Syringodium filiforme; turtles occurred less frequently in seagrass beds with the invasive Halophila stipulacea. During the night there is less activity when compared to day time hours. Our data confirm that Brewers Bay is an important foraging and resting habitat for juvenile green sea turtles and that their foraging movements center on areas with S. filiforme. These areas in return should receive focused management for both seagrass and reefs to protect green sea turtles. With this management these areas should receive protection from recreational boaters and tourists to prevent the spread of the invasive H. stipulacea
As green sea turtle (Chelonia mydas) populations in the Caribbean recover from historical overexploitation, growing environmental obstacles pose threats to the recovery of this species. The invasion of Halophila stipulacea seagrass in previously Syringodiumfiliforme and Halodule wrightii -dominated beds drastically alters the composition of green turtle foraging habitat. This change in forage supply for juvenile and adult green turtles in the Caribbean could impact their future habitat use and resource partitioning, information that conservation and management agencies use to implement protective guidelines for this species. We conducted a fine-scale tracking study of green turtles’ space use and movement patterns in Brewers Bay, St. Thomas to investigate their foraging selectivity in the mixed-species seagrass beds. The fine-scale positioning system(FPS) acoustic receiver array was deployed across ~1.5 km2 of the bay, which includes seagrass, coral reef, and sand/rock benthic habitat. Seventeen individual juvenile green sea turtles were tracked with acoustic transmitters with an estimated precision of ± 2meters. The native and invasive seagrass composition was mapped in the highest trafficked daytime area to pair with the turtles’ foraging locations. Turtles displayed typical diel patterns of movement with higher activity levels in shallow mixed-seagrass habitats during the day and lower activity levels in shallow reefs and rocky habitats at night. These movement results were linked to seagrass composition within the sampling grid using resource selection functions (RSF) to estimate turtle selection towards each seagrass species in Brewers Bay. Turtles were actively selecting the two native species, with no selection towards the invasive seagrass despite its high abundance. Interestingly, three individuals utilized foraging areas outside the sampling grid and in deeper water with monotypic invasive seagrass. This pattern of space use has not been observed in past tracking and observational studies in Brewers Bay, implying that part of this population has started modifying its foraging patterns to incorporate H. stipulacea.
Green sea turtles, Chelonia mydas, utilize coastal areas as foraging grounds for the majority of their lives. Human development of coastlines is increasing, but the effects of the urbanization of foraging grounds on green turtles are poorly understood. I used both manual and automated acoustic telemetry to determine the home ranges, movement behavior, and temporal patterns of site visitation of green turtles during 2009-2011 in San Diego Bay, California, a highly urbanized temperate foraging area. The home ranges of all tracked turtles were restricted to the southern portion of San Diego Bay, where eelgrass (Zostera marina) is abundant and where human activity is the lowest within the bay. Core activity areas coincided with eelgrass distribution or occurred adjacent to the warm water-effluent outfall of a waterfront power plant. Automated monitoring of sites throughout south San Diego Bay confirmed this finding, showing that green turtles most frequently visited the outfall of the power plant and areas known to contain eelgrass. This method also elucidated that turtle presence at the power plant was strongest during the winter and at night, whereas visitation to eelgrass areas was strongest during the spring and in the daytime. Turtle visitation to a high boat traffic shipping terminal was rare but occurred almost exclusively during the daytime, the period during which human activities in the area are also the highest. Manual tracking of green turtles similarly demonstrated that individuals ranged across larger portions of south San Diego Bay during the day, during which they exhibited high swimming speeds but highly non-linear movement. Turtle activity at night was primarily restricted to the power plant's effluent outfall channel and adjacent jetty. Nighttime movement was characterized by long periods of inactivity sporadically interrupted by brief, linear movements to new resting locations. Collectively, the results of this study paint a robust picture of the spatial, diel, and seasonal patterns of habitat use by green turtles in San Diego Bay. All data support the hypothesis that south San Diego Bay serves as important turtle habitat within the bay. Further, a combination of manual and automated acoustic telemetry enables a more complete understanding of turtle spatial ecology that would not have been possible with exclusive use of one technique. Future monitoring and modeling is required to document the potential effects of changing environmental conditions, including power plant closure, on green turtles resident to San Diego Bay. This study helps to assess the data gap of how turtles use urbanized foraging areas and changing coastal ecosystems, a currently novel scenario that will likely become commonplace in the face of increasing coastal development worldwide.
The Naval Weapons Station Seal Beach is undergoing construction to remove and replace an ammunition pier within the same vicinity as resident Seal Beach green sea turtles. The goal of this study was to determine green turtle movements, habitat use, and core areas of activity throughout the Seal Beach National Wildlife Refuge (SBNWR) and construction area in Anaheim Bay. Research took place prior to the commencement of construction through approximately six months during construction. Sixteen green turtles were equipped with FastLoc GPS-enabled satellite tags and tracked from November 2018 through July 28th, 2020. Volunteer visual data, hourly movements, and home range analyses determined that the majority of green turtle movements were within the inner portions of the SBNWR, although four turtles transitioned into Anaheim Bay, two turtles continued offshore prior to returning to Anaheim Bay and a single individual left the SBNWR and visited Huntington Harbour frequently. Core areas of activity (50% Utilization Distributions; UDs) for three spatial strata (SBNWR and Anaheim Bay combined, offshore, and Anaheim Bay only) were found to be 0.95 km2, 40.95 km2, and 0.27 km2, respectively. Individual 50% UDs within SBNWR ranged from 0.02 km2 to 1.43 km2 (mean ± SE: 0.36 ± 0.11 km2), and 95% UDs ranged from 0.18 km2 and 6.92 km2 (mean ± SE: 1.96 ± 0.57km2). These preliminary baseline results provide information on green turtle movements and core areas of activity in SBNWR, Anaheim Bay, and surrounding waters that will help inform conservation efforts to minimize impacts to green turtles.
Release of the 2000 Red List is a major landmark for IUCN. It is the first time that listings of animals and plants have been combined and the first time that the Red List has been produced on CD-ROM. The 2000 Red List combines new assessmentsincluding all bird species, many antelope and bat species, most primates and sharks, all Asian freshwater turtles, more molluscs, and many otherswith those from previous publications. The combination of animals and plants into a single list containing assessments of more than 18,000 taxa (11,000 of which are threatened species) and the move towards improved documentation of each species on the list means that a hard-copy version of the Red List would run to several volumes. This, combined with the fact that the Red List will be updated annually, led to the decision to release the Red List in electronic format, via the World Wide Web and as a CD-ROM.
Nearshore hardbottom reefs of Florida’s east coast are used by over 1100 species of fishes, invertebrates, algae, and sea turtles. These rocky reefs support reproduction, settlement, and habitat use, and are energy sources and sinks. They are also buried by beach renourishment projects in which artificial reefs are used for mitigation. This comprehensive book is for research scientists and agency personnel, yet accessible to interested laypersons including beachfront residents and water-users. An unprecedented collection of research information and often stunning color photographs are assembled including over 1250 technical citations and 127 figures. These shallow reefs are part of a mosaic of coastal shelf habitats including estuarine seagrasses and mangroves, and offshore coral reefs. These hardbottom habitats are federally designated as Essential Fish Habitats - Habitats of Particular Concern and are important feeding areas for federally-protected sea turtles. Organismal and assemblage responses to natural and man-made disturbances, including climate change, are examined in the context of new research and management opportunities for east Florida’s islands in the sand.
Mangroves are one of the most productive and biologically important blue-carbon ecosystems across the coastal intertidal zone of earth. In the current scenario of serious environmental changes like global warming, climate change, extreme natural disasters, mangrove forests play a vital role in mitigating greenhouse gas emissions and maintaining ecosystem balance. Mangroves are unique ecosystems with rich biological diversity of different taxonomic groups exhibiting great ecological and commercial importance. The book consolidates existing and emerging information on ecology of mangroves, with a special reference to their biodiversity and management. It emphasizes on the role of mangroves in providing various ecological services. The book is a comprehensive compilation covering all aspects of mangrove ecology. It is useful for students and researchers in ecology, plants sciences and environmental sciences.
