Alligators and crocodiles as indicators for restoration of Everglades ecosystems

Mazzotti, Frank J.; Best, G. Ronnie; Brandt, Laura A.; Cherkiss, Michael S.; Jeffery, Brian; Rice, Kenneth G.

doi:10.1016/j.ecolind.2008.06.008

Cited by 115 publications

(99 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Once classified as endangered in the early 1960s due to modification of habitat, water management, and poaching, population numbers increased in the 1970s coinciding with controls on harvesting (Hines 1979;Jacobsen and Kushlan 1984;Mazzotti and Brandt 1994;Rice et al 2005). Although current alligator population trends are uncertain, concerns exist that increasing drought frequency and dry down events could potentially affect the population (Mazzotti et al 2009). For example, south Florida experienced a severe drought in 2001, which negatively impacted populations of fish and macroinvertebrates, common food resources for large aquatic predators (Smith et al 2003;Trexler and Goss 2009).…”

Section: Introductionmentioning

confidence: 99%

Estimating Trends in Alligator Populations from Nightlight Survey Data

et al. 2011

Self Cite

View full text Add to dashboard Cite

Nightlight surveys are commonly used to evaluate status and trends of crocodilian populations, but imperfect detection caused by survey-and location-specific factors makes it difficult to draw population inferences accurately from uncorrected data. We used a two-stage hierarchical model comprising population abundance and detection probability to examine recent abundance trends of American alligators (Alligator mississippiensis) in subareas of Everglades wetlands in Florida using nightlight survey data. During 2001-2008, there were declining trends in abundance of small and/or medium sized animals in a majority of subareas, whereas abundance of large sized animals had either demonstrated an increased or unclear trend. For small and large sized class animals, estimated detection probability declined as water depth increased. Detection probability of small animals was much lower than for larger size classes. The declining trend of smaller alligators may reflect a natural population response to the fluctuating environment of Everglades wetlands under modified hydrology. It may have negative implications for the future of alligator populations in this region, particularly if habitat conditions do not favor recruitment of offspring in the near term. Our study provides a foundation to improve inferences made from nightlight surveys of other crocodilian populations.

show abstract

Section: Introductionmentioning

confidence: 99%

Estimating Trends in Alligator Populations from Nightlight Survey Data

et al. 2011

Self Cite

View full text Add to dashboard Cite

show abstract

“…Alligators consume various organisms such as fish, birds, and other aquatic fauna [15], and they play a role as top-predator, keystone species, and ecosystem engineer. Due to their ecological importance, alligators have been used as an indicator of ecosystem restoration in south Florida [16]. Because alligators have dominant top-down effects, understanding their movement behavior is especially important for interpreting the trophic interactions in a system [10].…”

Section: Introductionmentioning

confidence: 99%

Home range and movements of American alligators (Alligator mississippiensis) in an estuary habitat

et al. 2014

View full text Add to dashboard Cite

Background: Understanding movement patterns of free-ranging top predators throughout heterogeneous habitat is important for gaining insight into trophic interactions. We tracked the movements of five adult American alligators to delineate their estuarine habitat use and determine drivers of their activity patterns in a seasonallyfluctuating environment. We also compared VHF-and satellite-tracks of one of the alligators to examine tradeoffs in data quality and quantity. Results: All tracked alligators showed high site fidelity in the estuary, but estimated home range size and core-use areas were highly variable. Two alligators were relatively sedentary and remained in the upper stream zone. One alligator traveled to a transition zone between freshwater marsh and estuary habitat, but primarily remained in the upstream area. Two alligators traveled to the downstream zone into saline conditions and showed high salinity tolerance. Overall movement rates were highly influenced by salinity, temperature, and season. Both satellite and VHF radio telemetries resulted in similar home range, core-use area, and activity centers. Conclusions: This study reveals consistent use of estuary habitat by American alligators. The alligators showed variations in their movement pattern and seasonal habitat, with movement attributable to environmental factors. Although satellite-derived locations were more dispersed compared to locations collected using VHF radio-tags, data collected from VHF tracking omitted some habitat used for a short period of time, indicating the effectiveness of satellite telemetry to continuously track animals for ecosystem-scale studies.

show abstract

“…Usefulness of alligators as an indicator of ecological responses to ecosystem restoration is dependent on our ability to link responses to suitability of environmental conditions and hydrologic change (Mazzotti et al, 2009). Correlations between ecological responses and hydrologic changes may permit assessment of positive or negative trends in restoration.…”

Section: Discussionmentioning

confidence: 99%

Relationship between body condition of American alligators and water depth in the Everglades, Florida

Fujisaki

Rice

Pearlstine³

et al. 2009

Hydrobiologia

Self Cite

View full text Add to dashboard Cite

Feeding opportunities of American alligators (Alligator mississippiensis) in freshwater wetlands in south Florida are closely linked to hydrologic conditions. In the Everglades, seasonally and annually fluctuating surface water levels affect populations of aquatic organisms that alligators consume. Since prey becomes more concentrated when water depth decreases, we hypothesized an inverse relationship between body condition and water depth in the Everglades. On average, condition of adult alligators in the dry season was significantly higher than in the wet season, but this was not the case for juveniles/ subadults. The correlation between body condition and measured water depth at capture locations was weak; however, there was a significant negative correlation between the condition and predicted water depth prior to capture for all animals except for spring juveniles/subadults which had a weak positive condition-water depth relationship. Overall, a relatively strong inverse correlation occurred at 10-49 days prior to the capture day, suggesting that current body condition of alligators may depend on feeding opportunities during that period. Fitted regression of body condition on water depth (mean depth of 10 days when condition-water depth correlation was greatest) resulted in a significantly negative slope, except for spring adult females and spring juveniles/subadults for which slopes were not significantly different from zero. Our results imply that water management practices may be critical for alligators in the Everglades since water depth can affect animal condition in a relatively short period of time.

show abstract

Alligators and crocodiles as indicators for restoration of Everglades ecosystems

Cited by 115 publications

References 16 publications

Estimating Trends in Alligator Populations from Nightlight Survey Data

Estimating Trends in Alligator Populations from Nightlight Survey Data

Home range and movements of American alligators (Alligator mississippiensis) in an estuary habitat

Relationship between body condition of American alligators and water depth in the Everglades, Florida

Contact Info

Product

Resources

About