Abundance, Site-Fidelity, and Association Patterns of Coastal Bottlenose Dolphins (Tursiops truncatus) off Southeast Florida

The coastal bottlenose dolphin is well studied throughout its natural range, however, most of the study areas comprised wide, well-protected habitats such as bays and estuaries, and not narrow coastal sandbanks. This study identifies a residential group of coastal bottlenose dolphins utilizing the narrow sandbanks within the Northwestern Atlantic waters off the coast of Palm Beach County, Florida, USA. From 2014-2020, 313 boat surveys were conducted, and 585 individual dolphins were identified using photo-ID. Twenty-four animals were determined to be full-time and 66 animals were determined to be part-time residents. Full-time and part-time residents associated in three social tribes, with encounters consisting of members of multiple tribes commonly observed. Association patterns were highly correlated to site-fidelity, indicating the presence of a unique residential group which regularly interacts with transient animals likely passing between Central Florida and Biscayne Bay. Future research within this natural corridor will focus on habitat utilization by residents and transients, and the behavioral nature of encounters between social tribes

Investigating the Sub-Lethal Effects of Mercury Exposure Using Environmental Sentinels

Mercury (Hg) is a ubiquitous environmental contaminant that is bioaccumulative and toxic. Ecosystems accumulate high mercury concentrations throughout their food web based on their unique environmental characteristics, exposing predators in these environments to mercury concentrations that elicit toxic effects, which are rarely observed outside of the laboratory. These predators provide the opportunity to investigate the sub-lethal effects of chronic mercury exposure that occur prior to the onset of toxic effects. Here the American alligator is thoroughly assessed for use as a sentinel of human dietary mercury exposure. We find that wild healthy alligators from the southeastern Atlantic coast of the US are exposed to mercury concentrations comparable to human populations with several different diets, and can be used as a sentinel for lifetime mercury exposure. The range of mercury concentrations that alligators are exposed to provide the opportunity to examine biochemical changes as sub-lethal effects, along an increasing mercury gradient. We observe that DNA methylation and mercury concentration are inversely correlated, but may be reversible based on diet. This epigenetic modification provides as assessment tool that can also be used for prevention in humans. To investigate underlying biochemical changes associated with increasing mercury exposure, a laboratory model of chronic exposure was assessed using an NMR based metabolomics approach. The diamondback terrapin, which is an established sentinel for mercury exposure, experienced both sub-lethal, and toxic effects, providing the opportunity to examine the onset of toxicity. We observed changes in small molecules involved in oxidative stress management throughout the range of mercury exposures, prior to toxic effects being observed. The terrapins experiencing toxic effects had behavioral changes commonly associated with mercury poisoning, such as neurological and muscular impairment. Many small molecules were altered in these terrapins, but most were related to their impaired foraging abilities. The Adverse Outcome Pathway (AOP) framework is used to put these data into a greater context that can be used for risk assessment for humans and wildlife. The AOP framework can be used for the prevention of toxicity, and a more complete understanding of the sub-lethal changes associated with this toxic contaminant

Movements of short-finned pilot whales (Globicephala macrorhynchus) in the Macaronesian biogeographical region: a photo-identification analysis

Dissertação de mestrado, Biologia Marinha, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2016The short-finned pilot whale, Globicephala macrorhynchus Gray (1846), is a marine mammal species from the family Delphinidae. It is a top predator species, with a circumglobal distribution from warm-temperate to tropical regions, at varying distances from shore, including the Macaronesia region (NE Atlantic). Population connectivity can profoundly influence the distribution, persistence and ecological impact of local marine mammal species. Understanding population connectivity and its environmental drivers is critical for effective wildlife conservation and management, namely in a context of increased marine pollution associated to toxic contaminants, ocean noise and disruption of natural food webs. The aim of this study was to compare Globicephala macrorhynchus individuals within the Macaronesian’ archipelagos. It includes data (digital photographs) from Madeira between 2003 and 2015, from Azores between 1999 and 2015, from the Canary Islands between 1993 and 2015, and from Cape Verde in 2006. This thesis represents the first study comparing individuals from this species within the four archipelagos of the Macaronesia. In this thesis, the method used to study the animals’ connectivity was photo-identification, which is based on the analyses of natural markings in dorsal fins. The dorsal fins were cropped from photographs and were matched to available photo-identification catalogues for G. macrorhynchus from Madeira and photos from the other archipelagos not catalogued yet. The comparison was made by eyes using image softwares, based on the number of nicks and notches in the dorsal fin of the different individuals. Results showed that 19 short-finned pilot whales were matched, being 11 individuals between Azores and Madeira, and eight individuals between Canaries and Madeira. Of these, 69% were categorized with a residency status of “transient”, 26% of “resident”, and 5% of “visitors”. This thesis supports the importance of the Macaronesia region for this species, and highlights the need for common conservation policies across different archipelagos/countries.Os cetáceos (do latim Cetus "baleia" e do grego Ketos "enorme peixe") incluem 87 espécies de golfinhos, baleias e botos, e com uma grande variabilidade de comprimento, que vai de 1.5 a 33 metros. Os cetáceos marinhos têm dois tipos de aparelho digestivo, barbatanas e dentes: Odontoceti (baleias/golfinhos com dentes) e Mysticeti (baleias com barbas). Neste caso, irei focar-me nos Odontocetes, que normalmente são agregados em grupos, também conhecidos como pods, em que a estabilidade da estrutura do grupo é principalmente fornecida por laços entre mães e filhos, e de facto, os grupos são formados principalmente pelas mães e as respetivas crias. Geralmente os mamíferos marinhos são os principais consumidores na maioria dos níveis tróficos: desde zooplâncton a peixes predadores, sendo que alguns deles podem também alimentar-se de outros mamíferos marinhos. Conhecer os mamíferos marinhos é o primeiro passo para a sua conservação, sendo ainda mais importante no caso de algumas espécies que estão em risco de extinção devido à atividade humana (por exemplo, a sobrepesca de presas de cetáceos e a pesca de alguns mamíferos marinhos). A recente alteração natural e antropogénica do habitat coloca as espécies em risco. Além disso, este clade está em perigo porque se a população começar a diminuir, eles terão dificuldade em recuperar devido à sua maturidade sexual numa idade tardia e ao pequeno número de juvenis que a fêmea pode dar à luz (Perrin et al., 2009). A espécie levada em consideração durante este projeto de tese foi a baleia-piloto-tropical, Globicephala macrorhynchus (Gray 1846), que é uma espécie de mamíferos marinhos da família Delphinidae. Pode atingir um comprimento médio de seis metros, com um corpo robusto, uma cauda espessa e uma barbatana dorsal larga. No que diz respeito ao mergulho, pode atingir profundidades entre 1000 e 1300 metros com uma duração de mergulho de 21 a 27 minutos. Globicephala macrorhynchus é uma das principais espécies de predadores, com uma distribuição global que vai desde regiões temperadas a regiões tropicais, a diferentes distâncias da costa, incluindo a região biogeográfica da Macaronésia (NE Atlântico), que é conhecida por incluir os quatro arquipélagos vulcânicos, de norte para sul: Açores, Madeira, Canárias e Cabo Verde (Fernández-Palacios et al., 2011). A conectividade em subpopulações geograficamente separadas influência profundamente a distribuição, persistência e impacto ecológico das espécies de mamíferos marinhos locais. Compreender a conectividade da população e as influências ambientais é fundamental para a conservação da vida selvagem e gestão eficazes, devido ao perigo que esta espécie tem passado: perigo vindo da captura direta até aos anos 80 (Kasuya et al., 1984), captura acidental, especialmente durante a pesca do atum e do espadarte (Forney et al., 2007), poluição química, como POPs e DDT que se podem acumular nos músculos e tecidos blubber causando um impacto negativo (Dam et al., 2000). Para além disto, há a poluição sonora e energia acústica, que pode ser ou não intencional, como o sonar e a exploração sísmica e a propulsão do navio, respetivamente (Nowacek et al., 2007). Além disso, o cativeiro tem um impacto importante em G. macrorhynchus (Reeves, 1984) e na ruptura das cadeias alimentares naturais. O objetivo deste estudo foi organizar e atualizar um catálogo de foto identificação de G. macrorhynchus na Madeira (32 ° 45 'N / 016 ° 57' W), reunindo outras informações de foto-identificação existentes coletadas de diferentes organizações individuais, universidades e empresas de observação de baleias, entre 2003 e 2015 dos Açores (37 ° 44 'N / 025 ° 40' W), entre 1993 e 2015 das Ilhas Canárias (28 ° 17 'N / 016 ° 37' W), e em 2006 de Cabo Verde (14 ° 18'N / 022 ° 26'W). Após um estudo preliminar de foto-identificação de G. macrorhynchus efetuado entre as Ilhas Canárias e a Madeira em 2007, esta tese representa o primeiro estudo a comparar indivíduos dos quatro arquipélagos. O estudo dos cetáceos é difícil, uma vez que eles podem movimentar-se rapidamente e passar grande parte do seu tempo debaixo de água (Perrin et al., 2009). Várias técnicas são usadas para estudar a conetividade em populações de cetáceos marinhos, entre as quais, experiências de monitorização de marcação e recaptura, genética de populações e foto-identificação, sendo este último o método utilizado neste projeto. Esta técnica é baseada na análise de marcas naturais em barbatanas dorsais para identificação individual (e.g., incisões, arranhões, cicatrizes, formação de cristas dorsais, padrões de pigmentação e padrões de calosidade), e foi anteriormente aplicada a G. macrorhynchus para avaliar a organização social, a estrutura populacional e de residência e os padrões de movimento em vários arquipélagos. Para o presente estudo, as barbatanas dorsais foram analisadas a partir de fotografias obtidas e comparadas com catálogos de fotoidentificação disponíveis de G. macrorhynchus da Madeira e fotografias não catalogadas dos outros arquipélagos. A comparação das barbatanas destes animais foi feita visualmente, considerando-se o número de cortes, entalhes e arranhões. Os resultados obtidos durante este projecto demostram que indivíduos desta espécie movem-se dentro da área de estudo (baseado em 19 indivíduos identificados em diferentes arquipélagos), em particular entre as Ilhas Canárias e a Madeira (n=8), e entre os Açores e a Madeira (n=11). Embora não tenham sido encontrados movimentos de G. macrorhynchus entre os restantes arquipélagos estudados, não podemos ter certeza de que não estiveram presentes naqueles locais pelos seguintes motivos: é possível a presença de erros, em alguns casos os dados eram escassos e devido a um período de comparação pouco longo. Sem essas variáveis, pode haver maior probabilidade de ter G. macrorhynchus a corresponder também com outros arquipélagos da área estudada, por isso, seria interessante ter mais dados para comparar e, assim, adquirir um conhecimento completo e um melhor estudo do movimento da G. macrorhynchus na área de estudo. Este estudo sobre o movimento de G. macrorhynchus pode ajudar no conhecimento das espécies, da sua biologia e gestão da conservação

Temporal and spatial harvest patterns of river otter in Louisiana and its potential use as a bioindicator species of water quality

Louisiana is the leading state in number of river otters used in reintroduction programs in other states and in the production of pelts. However, habitat loss and degradation have prompted concern about the status of otter populations. This dissertation undertakes a spatial and temporal analysis of river otter harvest activity and examines environmental factors related to monitoring mercury levels in streams in Louisiana. Harvest data for 1957-2004 were analyzed to identify spatial and temporal trends in otter harvest activity. Changes have occurred in the last 20 years in the spatial dynamics of otter harvest in Louisiana, these include an increasing proportion of harvested otters coming from upland parishes in more recent years, and an increase in the proportion of trappers catching otters in that region. Spatial analysis indicated that this shift in harvesting activity has been gradual rather than abrupt. An explanation for this shift could be a greater interest of upland trappers in catching otters because of increasing otter pelt price and a decline in pelt price for other furbearer species. Analyses indicated that a management plan based on spatial control of harvest could be an option in Louisiana, with rice fields and protected areas playing an important role in the management/conservation plan. Temporal analysis suggested that the number of otters harvested 1 and 5 years ago has an impact on number of otters harvested at present time. An autoregressive model was developed to describe this association and to forecast number of otter pelts to be harvested 1 year in the future. The structure identified in the harvest data was used to develop a model to describe the dynamics of the otter populations. The simulation using 4-year and 8-year periods offered a reasonable approximation to the estimated cyclic dynamics of otter population in Louisiana. Mercury levels in otters were compared to levels in fish collected in different streams in Louisiana. Mercury levels in otters were higher than in fish. Otter samples also identified streams where mercury level in water may require further analysis. These results suggested that a mercury monitoring program based on river otters could be feasible in Louisiana

Use of satellite telemetry to delineate bald eagle activity centers for hazard mitigation and land planning within the upper Chesapeake Bay. Final Report

Sustaining the duel military and environmental stewardship missions on Aberdeen Proving Ground (APG) has become increasingly challenging as the number of eagles using the installation has grown dramatically. Military testing and training activities conducted on APG are vital to national security. APG likely holds the greatest conservation value for bald eagles of any federal property along the Atlantic Coast. The property supports a complex mixture of eagles including a growing breeding population that is rapidly approaching saturation, a large population of non‐breeding residents, and migrant populations from the northeast and southeast. Major activity centers such as active nests, communal roosts and foraging areas are protected under the disturb and sheltering provision of the federal Bald and Golden Eagle Protection Act. The level of site‐specific information on eagles required to tightly integrate their needs into the space requirements of a diverse and dynamic military operation has not been available. The focus of this project has been to collect and provide eagle information that will enable the incorporation of effective environmental planning into the military mission. Between 2007 and 2009 satellite transmitters were deployed on a large (n = 65) cohort of eagles that represent the cross section of populations that use APG. Between 2007 and 2011 transmitters collected nearly 700,000 GPS locations from within every state and Canadian province along the Atlantic Coast confirming APG’s role as a hub of eagle activity within eastern North America. Locations (n \u3e 320,000) within the upper Chesapeake Bay were used in spatial models to develop probability surfaces that identify high‐use activity centers by season within APG. Midnight locations (n \u3e 10,300) were used in separate spatial models to delineate communal roosts. Results of this study provide site‐specific information designed to inform future management decisions. Maps reveal the locations of significant communal roosts, foraging areas, loafing areas and movement corridors used by eagles on APG. Levels of use are quantified by location to facilitate prioritization of sites for management consideration. Seasonal and time‐of‐day patterns are provided to inform the scheduling of activities. The intersection of activity centers with the electrical infrastructure is examined to identify locations with the highest mortality risk. Lines intersecting with high‐use activity centers have produced mortality rates that are 42 times higher than lines intersecting with low‐use areas. Site‐specific information is provided to allow for the phasing of hazard mitigation. This report concludes the largest investigation of space use by bald eagles ever conducted. The project has clarified several aspects of eagle ecology within the upper Chesapeake Bay and has moved the science of eagle management forward in a way that will inform management throughout the species range. The still ongoing tracking database holds a great deal of promise for new ecological discoveries and management solutions

River Report. State of the Lower St. Johns River Basin, Florida: Water Quality, Fisheries, Aquatic Life, Contaminants, 2022.

https://digitalcommons.unf.edu/sotr/1012/thumbnail.jp

Niche partitioning amongst northwestern Mediterranean cetaceans using stable isotopes

Ten species of cetaceans coexist in the Mediterranean Sea, one of the richest seas in biodiversity and endemisms worldwide. The conservation status of Mediterranean cetaceans has been a concern for many years, particularly due to increasing anthropogenic threats such as global warming and overfishing. We established the stable isotopic niches of carbon, nitrogen, and sulphur for five species of cetaceans inhabiting the northwestern Mediterranean Sea to elucidate the mechanisms of coexistence. The fin whale exploited epipelagic habitats with a low trophic level; the bottlenose dolphin was mostly neritic and had a high trophic level; the Risso's dolphin was oceanic and fed bathypelagically and at a high trophic level; finally, the common and striped dolphins displayed epipelagic distributions and similarly intermediate trophic levels. The isotopic niches of all species were exclusive except the common and striped dolphins, whose niches overlapped by 25%. These results suggest that the majority of species avoid competitive exclusion by trophic or spatial segregation with the exception of striped and common dolphins, in which interspecific competition is apparent. It is suggested that this competition brought the striped dolphin to displace the common dolphin from part of its distribution range, restricting it to the southern fringe of the western Mediterranean and, particularly, to the Alboran Sea. In this area, coexistence of the two species would be permitted by some degree of spatial segregation between them and a remarkably high productivity, all which mitigate competition

MICROBIAL MERCURY METHYLATION AT CADDO LAKE: A MOLECULAR ECOLOGY APPROACH

Caddo Lake in northeastern Texas is a cypress-Spanish moss dominated lake ecosystem. Contamination of mercury (Hg), especially methylmercury (MeHg), was reported in this lake a decade ago. MeHg is a neurotoxicant accumulated in major fish species and reptiles. Due to the biomagnification feature of MeHg transfer, Hg contamination in the fishes of Caddo Lake has caused health concerns for the wildlife and local people. However, the source and synthesis of MeHg in this lake, primarily the microbial Hg methylation mechanisms, have not been investigated. We investigated the lake for the past three years (2016-2018), by taking sediment and plant samples in several locations of the lake wetland habitats which showed high MeHg levels in fish from previous studies. We employed a culture-independent molecular approach to identify the Hg-methylating microbial community present in sediment as well as the sporangia of the invasive species Giant salvania (Salvania molesta). Total organic carbon, total Hg, MeHg, sulfate, iron(III) and other biogeochemical factors were analyzed in the lake ecosystem. We extracted genomic DNA from all samples and detected functioning genes including the Hg methylation genes (hgcAB), methyl-coenzyme M reductase genes (mcrA) as well as 16S rRNA genes. The 16S rRNA genes were characterized by high throughput next generation sequencing on Illumina MiSeq. In lake sediment samples, a total of 6402 OTUs were discovered, dominated with Crenarcheales (9.7%), Bacteroidales (5.2%), Syntrophobacterales (3.1%). Our results indicated that the lake sediment samples contained diverse potential mercury methylators, including Syntrophobacteraceae (1.4%), Geobacter spp. (1.1%), SRB Desulfovibrio-Desulfobulbus-Desulfobacter (0.6%), and methanogenic archaea (0.6%). It seems that microbial MeHg production in this wetland habitat could be influenced by a complex syntropy among Syntrophobacterales, methanogens, and sulfate-reducing bacteria. Results based on the geochemical data and hgcA gene detection and quantification suggest that Johnsons Ranch and Judd Hole are likely the hot spots for MeHg production in this lake ecosystem

River Report. State of Lower St. JOhns River Basin, Florida: Water Quality, Fisheries, Aquatic Life, Contaminants, 2023

https://digitalcommons.unf.edu/sotr/1013/thumbnail.jp

Impacts of climate change, human land use, and mercury contamination on Southern Appalachian Plethodontid salamanders

The Southern Appalachian Mountains are home to the greatest diversity of Plethodontid Salamanders in the world. The future for these salamanders is uncertain as globally amphibians have been experiencing significant population declines. We investigated the impact of habitat loss, chemical contaminants, and climate change on Plethodontid salamanders in northeastern Tennessee and southwestern Virginia. Four-toed salamanders (Hemidactylium scutatum) were negatively impacted by powerline right-of-way (ROW) mowing. Embryonic and larval survival significantly decreased in ROW after mowing and required up to 3 years of vegetation regrowth to reach post mowing survival. We also investigated mercury contamination in black-bellied salamanders (Desmognathus quadramaculatus) from Whitetop Mountain, Virginia. We found these salamanders to be contaminated with mercury levels equivalent to salamanders from point source pollution streams. Additionally, salamander from streams facing the prevailing wind direction had significantly greater levels of mercury contamination. To help land managers in planning long range habitat goals for the Mount Rogers National Recreation Area, we also developed salamander occupancy models based on parameters describing forest structure and composition. Elevation or other abiotic factors had a greater association to occupancy than many forest parameters. Lastly, to determine the influence of climate change on Mount Rogers Nation Recreation Area (MRNA) salamander distributions, we compared current distributions with those from the 1950s and 1990s and examined regional temperature changes since 1948. Plethodon welleri, a high elevation endemic, moved down slope since both the 1950s and 1990s. Plethodon yonahlossee expanded its range both up and down slope, but P. cylindraceus experienced range constrictions since the 1950s. No significant differences were observed for regional temperatures since 1948. We also modeled future salamander occupancy based on current mean temperature preferences. Using the Canadian Centre for Climate Modeling and Analysis Coupled Global Climate Model (CGCM) and the Hadley Centre for Climate Predication and Research (HAD) global circulation models with 2 different CO2 [carbon dioxide] emission projections, we projected the extirpation of P. welleri, D. organi, and Eurycea wilderae from Whitetop Mountain by 2070. Our results provide land managers with data necessary to better prepare for the challenges to maintain Plethodontid salamander populations