Habitat (Ecology)

The ecosystem created by pelagic Sargassum is important in the life histories of a
number of economically and ecologically important associated organisms. Fishes play a
vital role in this food web and nutrient flow within these systems, but it is unknown how
they locate these floating habitats. This study examined the role of natural chemical cues
from Sargassum patches and the synthetic chemical Dimethylsulfonionpropionate
(DMSP) for an associated fish, the planehead filefish (Stephanolepis hispidus) and a
control fish species not associated with Sargassum, the masked goby (Coryphopterus
personatus). Choice trials with a Y-maze apparatus determined that S. hispidus
responded significantly to chemical cues from Sargassum while C. personatus did not.
DMSP cues did not result in any significant behavioral responses for either fish.
Demonstrating that S. hispidus can respond to chemical cues from Sargassum helps
further our understanding of this unique floating algal reef and how fishes may locate it.

This investigation compared statistical parameters for the blood serum chemistries
of free ranging Osprey nestlings from Florida Bay and an Osprey population from Lake
Istokpoga, in Central Florida (Chapter 1). Florida Bay Ospreys showed higher mean rank
values for alanine aminotransferase (H=6.79, P=.009), alkaline phosphatase (H=6.48,
P=.011), and sodium (H=5.7, P=.017), and Central Florida had higher mean rank values
potassium (H=13.19, P=.000) and carbon dioxide (H=6.23, P=.013). Serum chemistries
values were also compared between free-ranging Bald Eagle and Osprey nestling in
Florida Bay estuary in southern Florida (Chapter 2). There were significant differences
between serum values of Bald Eagle and Osprey nestlings. Bald Eagle serum values were
higher for total protein (H=17.833, P=.00002), Albumin (H=7.449, P=.006), Aspartate
aminotransferase (H=113.153, P =.0001), and Calcium (H=7.148, P = 008). Osprey serum values were higher for alanine aminotransferase (H=11.824, P = 0.0005), alkaline phosphatase (H=105.5, P =.0001), creatine kinase (H=13.465, P = 0.0002), carbon dioxide (H=4.443, P = 0.035) and cholinesterase (H=99.3, P=.0001). Sixteen nestling Bald Eagles were fitted with satellite platform transmitter terminal (PTT) or VHF radio transmitter package for a duration of six years (Chapter 3)= to identify their movement and dispersal. One of the 15 eagles migrated to North Carolina, whereas the other 14 (93%) confined their movements to Florida. Tracking duration per individual ranged from 82 to 1,531 days. We estimated first-year survival as 52% and 67% for the period from 1.5 to 3 years. Diamondback Terrapins (Chapter 4) were evaluated by an integrated assessment of physical, chemical, and physiological parameters. Extreme site fidelity of the turtles to mangrove habitat was evident along with a strong female biased sex ratio. There was a significant difference in the total number of individuals collected at the two sites (P =. 01) despite the total size and shorelines of the two sites being very nearly the same. Total recapture rate was 70% for combined population (TLK = 80% and CKW = 48%). We provide blood serum values and microbial cultures as baselines from these turtles in the wild.

The Sargassum community is comprised of a unique and diverse assemblage of organisms. Habitat detection by two of the most common invertebrates, Latreutes fucorum and Leander tenuicornis , was investigated. Results of this study do not support that either L. fucorum or L. tenuicornis respond to chemical cues released by the Sargassum habitat in the absence of other information. Habitat selection of both shrimp species was examined as well. Both L. fucorum and L. tenuicornis selected live Sargassum over artificial Sargassum . Moreover, L. fucorum selected Sargassum natans over Sargassum fluitans when only visual cues were available, whereas large-sized L. tenuicornis selected S. fluitans under the same conditions. Conversely, habitat selection trials combining both chemical and visual cues resulted in no preference between the two Sargassum species by either shrimp species. Additional ecological factors that possibly influence habitat location and selection are discussed as well as the importance of Sargassum in terms of pelagic fisheries management.

An innovative technique of evaluating resource selection for black rhino (Diceros bicornis) was used to assess the population utilization distribution (PUD) within a rhino sanctuary in Liwonde National Park, Malawi. The PUD enabled an evaluation of responses to habitat variables over a spatial gradient of resource selection. A Geographic Information System (GIS) was constructed using vegetation, browse availability, roads, rivers, water holes and satellite imagery. Linear models were developed to quantify habitat variables within the black rhino sanctuary and park. The sanctuary model was calibrated within a known core area (R^2=0.42, P<0.001), validated in a second area (R^2=0.56, P<0.001) within the sanctuary and, subsequently, used to predict potential black rhino habitat within the remaining sanctuary boundaries. The model for the entire Liwonde National Park predicted additional black rhino habitat (R^2=0.25, P<0.05). Population utilization distribution was found to be a powerful conservation tool for determining suitable black rhino habitat.

This study compared the avian communities of treatment wetlands in South Florida called Stormwater Treatment Wetlands (STAs) to those in natural marshes and crop lands, and examined factors that influenced the size and structure of the avian communities within the STAs. The STAs contained a more abundant, rich and distinct avian community compared to reference land types. The STAs were dominated by wintering waterfowl, and therefore community patterns fluctuated more seasonally other land types. Within the STAs, density and richness in the fall and winter were much greater in the submerged aquatic vegetation than in the mixed emergent vegetation when waterfowl were present. The STAs maintain two vegetation treatments which enhanced their biodiversity value by supporting distinct avian communities with different migratory strategies This suggests the increase in treatment wetlands could partially offset the loss of natural wetlands, but avian communities in treatment wetlands are not surrogates for natural wetlands.