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Urban living influences the nutritional quality of a juvenile shark species
Abstract and Figures
The field of marine urban ecology is a nascent, but growing area of research. An understanding of how urbanization may alter the diets and nutrition of marine species living in urbanized coastal habitats is limited. In the present study, we investigated the influence of urbanization on dietary patterns and nutritional quality of the nurse shark Ginglymostoma cirratum, a coastal epibenthic mesopredator. We tested the hypothesis that sharks sampled in urbanized areas (hereafter, ‘urban sharks’) would exhibit lower nutritional quality than individuals sampled in adjacent, but more pristine areas (hereafter ‘non-urban sharks’). To accomplish this, we compared plasma fatty acid profiles of juvenile nurse sharks in proximity to Miami, a large coastal city, within Biscayne Bay, Florida. Results revealed that urban sharks contained higher levels of plasma saturated and bacterial fatty acids compared to non-urban sharks. Urban sharks also exhibited lower proportions of essential fatty acids (i.e., highly unsaturated fatty acids, HUFAs), mainly due to low contributions of omega-6 HUFAs. These results suggest that urban sharks consumed lower-quality food resources than conspecifics in less impacted areas. The apparent poor nutritional quality of prey consumed by shark living in urban areas may have several long-term consequences on their health and growth.
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... However, some ω-6 fatty acids are also present in anthropogenic-based diets (Lopes et al., 2022), and an unbalanced high ω-6/ω-3 ratio can indicate a low-quality diet and subsequently, higher susceptibility to inflammation and diseases (Simopoulos, 2002). On the other hand, we anticipate higher concentrations of bacterial odd-chain fatty acids, trans fatty acids and oleic and vaccenic acids in Scopoli's shearwaters, because these groups of fatty acids are highly correlated with exposure to urban and industrial waste discharges, domestic sewage, and bacteria growing on organic matter (Baylin and Campos, 2006;Jiménez Martínez et al., 2019;Rangel et al., 2021;Rocchetta et al., 2014). ...
... ARA is an essential fatty acid, used as an important indicator of good quality of diet, and is also important to regulate important physiological processes such as inflammation and immune responses in healthy organisms (Arab and Akbar, 2002). Rangel et al. (2021) also found higher concentrations of ARA in nurse sharks (Ginglymostoma cirratum) inhabiting a non-polluted area, in comparison with individuals from a more urbanised area, near the city of Miami (USA). Accordingly, these results support our hypothesis of a better quality of resources in Berlenga Island, located in the Northeast Atlantic Ocean, when compared to the Chafarinas Islands, located in a more urbanised and industrialised coastline, in the western Mediterranean Sea. ...
... The higher concentrations of these bacterial FAs in Scopoli's shearwaters could also be potentially associated with anthropogenic-induced processes which, along with the higher temperatures of Mediterranean waters, create optimal conditions for the growth and proliferation of these microorganisms. Higher concentrations of C18:1 ω-9+ω-7 and odd-chain FAs have also been found in bivalves and nurse sharks inhabiting urbanised areas when compared to individuals from less-polluted areas (Rangel et al., 2021;Rocchetta et al., 2014). Other studies also found higher concentrations of C18:1 ω-9 in urban yellow-legged gulls in comparison to natural colonies (de Faria et al., 2021;Lopes et al., 2022). ...
Coastal urbanisation negatively affects marine ecosystems through habitat degradation and pollution. Cory’s
(Calonectris borealis) and Scopoli’s (C. diomedea) shearwaters are closely related species inhabiting the Northeast
Atlantic Ocean and the Mediterranean Sea, respectively. This study assesses the fatty acid profile, with the
trophic and foraging ecology, of Cory’s and Scopoli’s shearwaters breeding at Berlenga (Atlantic Ocean) and
Chafarinas (Mediterranean Sea) Islands. The diet quality of Scopoli’s shearwaters is expected to be generally
lower, characterised by reduced levels of ω-3 fatty acids. Additionally, higher concentrations of specific fatty acid
trophic markers are anticipated, reflecting the Mediterranean’s semi-enclosed environment, low productivity,
and pollution challenges. These markers include oleic acid, vaccenic acid, trans fatty acids (indicative of urban
and industrial discharges), and odd-chain fatty acids (indicative of bacterial presence). This study supported
these predictions, with Scopoli’s shearwaters foraging in the Mediterranean having higher concentrations of oleic
and vaccenic acids, odd-chain fatty acids, and trans-palmitoleic acid in their plasma. Yet, concentrations of ω-3
were also higher in Scopoli’s shearwaters. This may result from diverse prey availability and selection, and
different habitat exploitation, partially supported by differences in the trophic ecology and foraging patterns of
both species; or from an enhanced immunological basal response of Scopoli’s shearwaters to cope with higher
anthropogenic pressure in the western Mediterranean Sea. Further studies including specific diet and contaminant
analyses are crucial to understand differences in fatty acid profiles of seabirds inhabiting both oceanic
basins and the implications of diet quality for seabird populations.
... Studies on the habitat colonized by Atlantic Nurse Sharks were published between 1950 and 2021 (Appendix S2) and followed a similar pattern to the distribution studies. Most data were obtained from the Floridian ecoregion (N = 13; Gilmore et al., 1977;Smith & Herrkind, 1992;Carrier & Pratt, 1998;Castro, 2000;Wiley & Simpfendorfer, 2007;Pratt & Carrier, 2007;Adams & Paperno, 2007;Ward-Paige et al., 2010;Hannan et al., 2012;Pratt et al., 2018;Rangel, Hammerschlag & Moreira, 2021;Gutowsky et al., 2021;Tinari & Hammerschlag, 2021) The South Atlantic province had a lower variety of habitats associated with the Nurse Sharks, being composed of reefs and sandy and rocky bottoms (28.6% for each type) (Fig. 3B). Studies performed within MPAs had a greater abundance and diversity of habitat types than in locations outside these borders (Fig. 4). ...
... The destabilization generated by reef habitat degradation has effects that may scale up to the ecosystem level, leading to the loss of filtering services, oxygen depletion, and the extinction of commercially important fish and invertebrates (Worm et al., 2006). The effect of altered habitats and the relevance of habitat in maintaining species' healthy has already been evidenced by Rangel, Hammerschlag & Moreira (2021), which showed lower nutritional quality in urban Atlantic Nurse Sharks compared to non-urban sharks. Thus, further studies should focus on the effects of the loss or degradation of specific habitats on the populational attributes of the Atlantic Nurse Sharks which are key to unveiling the patterns described in this study and can subsidize conservation measures with context-dependent information. ...
... 1.077−1.02M;Ferreira et al., 2013;Afonso, Andrade & Hazin, 2014;Hannan et al., 2012;Rangel, Hammerschlag & Moreira, 2021). The group 1:0.5 had higher occurrences in sandy and seagrass types but also occurred in reefs and rocky habitats (1F:0.43−0.56 ...
Human activities have led to the loss of critical habitats for aquatic species at such an accelerated rate that habitat modification is considered a leading threat to biodiversity. Sharks and rays are considered the second most threatened group of vertebrates that have also suffered from habitat loss, especially in nursery grounds and reef-associated species. In this sense, actions toward the conservation of critical grounds for species survival are urgently needed, especially for those threatened with extinction. This study aimed to gather and provide information on the worldwide distribution and habitat association of the ‘vulnerable’ Atlantic Nurse Shark Ginglymostoma cirratum through a literature review performed at the Dimensions research database. A total of 30 studies published between 1950 and 2021 were retained since they defined at least the type of habitat in which G. cirratum was associated. Most studies covered the Floridian ecoregion, where G. cirratum is more common and abundant. Reefs, seagrass, sandy, rocky, mangrove, and macroalgae accounted for the majority of habitat associations, with a higher diversity of habitats detected within marine protected areas (MPAs). Ginglymostoma cirratum was recorded at a maximum depth of 75 m, temperatures ranging from 25 °C to 34 °C, and salinities between 31 and 38 ppt. Neonates were associated with shallower habitats (
... Queiroz et al. 2016). Recently, Rangel et al. (2021a) found that nurse sharks sampled in urban-impacted areas of Biscayne Bay had higher concentrations of plasma-saturated and bacterial fatty acids compared to conspecifics sampled in southern, less urban-impacted areas of the Bay. This result is indicative of a dietary pattern of feeding on a bacterial-based food web; for example, due to domestic sewage effluent that is highly correlated with urbanization (e.g. ...
... Sharks feeding in urban areas may be feeding on lower nutritional quality items. For example, dietary biomarkers from nurse sharks sampled in Biscayne Bay revealed urban nurse sharks had relatively lower percentages of essential fatty acids, higher saturated fatty acids, and increased bacterial markers compared to conspecifics sampled in less urbanized areas (Rangel et al. 2021a). Such poor nutritional quality prey could be the result of sharks feeding on fish carcasses that have been cleaned of meat and/or by sharks feeding on poor quality prey found in urban areas resulting from nutrient runoff causing lower transfer rate of physiologically important essential fatty acids to higher trophic levels (Gladyshev et al. 2012, Gomes et al. 2016, Whorley et al. 2019, Rangel et al. 2021a. ...
... For example, dietary biomarkers from nurse sharks sampled in Biscayne Bay revealed urban nurse sharks had relatively lower percentages of essential fatty acids, higher saturated fatty acids, and increased bacterial markers compared to conspecifics sampled in less urbanized areas (Rangel et al. 2021a). Such poor nutritional quality prey could be the result of sharks feeding on fish carcasses that have been cleaned of meat and/or by sharks feeding on poor quality prey found in urban areas resulting from nutrient runoff causing lower transfer rate of physiologically important essential fatty acids to higher trophic levels (Gladyshev et al. 2012, Gomes et al. 2016, Whorley et al. 2019, Rangel et al. 2021a. Nurse sharks sampled in ur ban areas also had fatty acid profiles indicative of relatively lower prey diversity (mainly piscivores), while non-urban nurse sharks had fatty acid profiles indicative of relatively higher prey diversity, including fishes, crustaceans, and mollusks, which could have also impacted their nutrition (Rangel et al. 2021a). ...
Understanding and ultimately predicting how marine organisms will respond to urbanization is central for effective wildlife conservation and management in the Anthropocene. Sharks are upper trophic level predators in virtually all marine environments, but if and how their behaviors are influenced by coastal urbanization remains understudied. Here, we examined space use and residency patterns of 14 great hammerheads Sphyrna mokarran , 13 bull sharks Carcharhinus leucas , and 25 nurse sharks Ginglymostoma cirratum in proximity to the coastal metropolis of Miami, Florida, using passive acoustic telemetry. Based on the terrestrial urban carnivore literature, we predicted sharks would exhibit avoidance behaviors of areas close to Miami, with residency patterns in these urban areas increasing during periods of lower human activity, such as during nocturnal hours and weekdays, and that dietary specialists (great hammerhead) would exhibit comparatively lower affinity towards highly urbanized areas relative to dietary generalists (bull and nurse shark). However, we did not find empirical support for these predictions. Space use patterns of tracked sharks were consistent with that of ‘urban adapters’ (species that exhibit partial use of urban areas). Modeling also revealed that an unmeasured spatial variable was driving considerable shark residency in areas exposed to high urbanization. We propose several hypotheses that could explain our findings, including food provisioning from shore-based activities that could be attracting sharks to urban areas. Ultimately, the lack of avoidance of urban areas by sharks documented here, as compared to terrestrial carnivores, should motivate future research in the growing field of urban ecology.
... The synergistic effects of coastal urbanization can directly or indirectly affect the behavior and physiology of marine predators by reducing the availability and quality of their prey (e.g. Rangel et al., 2021a) and altering coastal food webs though the bottom-up (i.e. predators are impacted by alteration in prey and basal resources) and top-down controls (i.e. ...
... Pacoureau et al., 2021), the sublethal effects of urbanization, including habitat loss and pollution, also have significant long-term impacts on coastal populations (Dulvy et al., 2021). For instance, plasma fatty acids measured in the mesopredatory nurse sharks (Ginglymostoma cirratum) suggest this species consumes lower-quality food resources in highly urbanized areas as compared to conspecifics in relatively low urban-impacted areas (Rangel et al., 2021a). Also, previous studies have found higher infertility rates (Gelsleichter et al., 2005) and epigenetic modifications (Beal et al., 2021) in sharks exposed to high concentrations of contaminants associated with urbanization. ...
... body condition) between blacktip sharks sampled in two different areas exposed to varying degrees of coastal urbanization in South Florida. Based on previous findings in the study area, which found differences in the plasma lipid metabolites and fatty acid profiles of nurse sharks exposed to urbanization (Moorhead, 2019;Rangel et al., 2021a), we hypothesized that blacktip sharks sampled within highly urbanized areas would exhibit higher body condition, but lower diet quality, compared to conspecifics sampled in neighboring areas exposed to relatively lower levels of urbanization (Fig. 1). We therefore predicted that blacktip sharks exposed to greater market gravity would exhibit an enriched δ 15 N and lower overall proportion of n3 PUFAs and of both diatoms and dinoflagellates fatty acid markers due to the increased contribution of anthropogenic nutrient enrichment (e.g. ...
The synergistic effects of coastal urbanization have dramatically impacted biological communities. Yet, few studies have investigated how urbanization can influence the diet quality and trophic ecology of coastal sharks. In a preliminary study, we examined for spatial variation in the nutritional ecology of a highly active marine predator, the blacktip sharks (Carcharhinus limbatus) exposed to regional differences in coastal urbanization in southeast Florida. We used medium-term nutritional indicators (i.e., body condition; whole blood stable isotopes [δ¹⁵N and δ¹³C]) and short-term dietary markers (i.e., plasma fatty acid profiles) to test the hypothesis that the nutritional ecology of marine predators would differ in areas exposed to increased urbanization. Our initial results showed that blacktip sharks sampled in high urbanized area (hereafter, ‘urban sharks’) exhibited relatively higher body condition, blood δ¹⁵N levels, and percentages of saturated fatty acids compared to sharks sampled in low urbanized area (hereafter ‘non-urban sharks’). Collectively, these results suggest a possible positive alteration in the amount of food consumed by sharks and/or in the caloric value of their prey. We also found lower percentages of bacterial markers and higher values of dinoflagellate markers in urban sharks. Compared to more resident species evaluated in the region, we did not detect a reduction in diet quality (in terms of essential fatty acids) in this highly active species exposed to urbanization. Therefore, it is possible that the lifestyle and feeding behavior have an influence on the quality of food consumed by urban sharks, and maybe the impacts of urbanization are more pronounced in resident, sedentary and benthic species.
... Estes et al., 2016;Hammerschlag et al., 2019). For instance, regional variation in dietary patterns of predators can be driven by ontogenetic variations (Aines et al., 2018;Dicken et al., 2017), food availability, prey preferences (Acuña-Marrero et al., 2017;Salinas-de-León et al., 2019), intraand interspecific interactions (Every et al., 2019), as well as by urbanization (Rangel et al., 2021a) and tourism provisioning (Semeniuk et al., 2009;Meyer et al., 2019). Such knowledge is particularly relevant for highly migratory predators, such as large sharks, due to their wide areas of space use and high energetic requirements (e.g. ...
... Plasma fatty acid profiles were used as short-term dietary markers to make inferences about prey quality (McMeans et al., 2012;Beckmann et al., 2014;Rangel et al., 2020Rangel et al., , 2021a, and basal food chain dependencies (e.g., bacteria, diatoms, dinoflagellates; Dalsgaard et al., 2003). Because fatty acids are transferred with little modification from prey to predator, they are especially relevant biomarkers to study diet patterns and nutritional shifts in the urbanization context (Budge et al., 2006;Iverson, 2009;Gomes et al., 2016). ...
... Surprisingly, we found higher proportions of n3 PUFA, mainly DHA, in sharks sampled in South Florida waters, suggesting consumption of higher quality food resources compared to Bahamas. This result differ from recent research which found that nurse sharks (Ginglymostoma cirratum) sampled in highly urbanized areas exhibited higher levels of plasma saturated and bacterial fatty acids compared to conspecifics sampled in adjacent minimally urbanized areas (Rangel et al., 2021a). Similarly, nurse sharks from highly urbanized sites also exhibited lower proportions of essential fatty acids (i.e., highly unsaturated fatty acids, HUFAs), mainly due to low contributions of omega-6 HUFA (Rangel et al., 2021a). ...
How varying levels of human activity, such as proximity and size of the nearest market (i.e., market gravity), influence the nutritional ecology and physiological condition of highly migratory marine predators is poorly understood. In the present study, we used a non-lethal approach to compare the concentration of metabolic hormones (i.e. corticosteroids and thyroid hormones) and plasma fatty acids between juvenile female tiger sharks (Galeocerdo cuvier) sampled in two areas of the subtropical north Atlantic, which differed markedly in their levels of coastal urbanization, Florida and the Bahamas (high versus low, respectively). We hypothesized that juvenile female tiger sharks sampled in water surrounding high coastal urbanization (Florida), would exhibit evidence of lower prey quality and higher energetic demands as compared to individuals sampled in relatively less urbanized areas of Northern Bahamas. Results revealed that relative corticosteroid levels (a proxy for energy mobilization) were higher in juvenile female tiger sharks sampled in Florida; however, no differences were found in concentrations of thyroid hormones (proxies of energetic adjustments) between the two locations. We found higher percentages of omega-3 polyunsaturated fatty acids (indicative of high prey quality) in juvenile tiger sharks from Florida, whereas higher percentages of bacterial markers (often indicative of domestic sewage effluent) were detected in the individuals sampled in the Bahamas. Taken together, these findings do not suggest that the differences in nutritional quality and metabolic condition found between the two sampling locations can be fully attributed to foraging in areas exposed to differing levels of urbanization. We speculate that these patterns may be due to the highly migratory nature and generalist feeding strategy of this species, even at the juvenile life stage, as well as proximity of sampling locations from shore.
... For instance, French et al. (2011) related diminished reproductive rates and population declines in California sea lions (Zalophus californianus) with the proximity to urbanized areas. In sharks, variability in nutritional quality has been ascribed to lower-quality prey being consumed by individuals exposed to urban influence compared with conspecifics from less-impacted areas (Rangel et al., 2021a). Also, sharks were less likely to occur and exhibited more cautious behaviors at impacted areas close to an urban center than in more pristine areas (Juhel et al., 2019), although such effects might not generalize (Hammerschlag et al., 2022). ...
... Evidence of tiger sharks not responding to human settings as expected has been reported. For example, Rangel et al. (2021b) found no relevant differences in nutritional quality and metabolic condition between tiger sharks sampled in an urbanized area and in a pristine area, even though another shark species (i.e., the Atlantic nurse shark, Ginglymostoma cirratum) sampled in the same locations exhibited clear differences in those indicators (Rangel et al., 2021a). In The Bahamas, where shark-focused diving tourism spans year-round, no effects of continued provisioning on tiger shark habitat use and diel behavior have been found (Hammerschlag et al., 2017a). ...
... Some studies have found that sharks residing in wastewater-impacted areas are exposed to and can accumulate measurable quantities of human pharmaceuticals [66]. Furthermore, Rangel et al. [67] found that juvenile nurse sharks sampled in highly impacted urban areas of Biscayne Bay in Miami had higher concentrations of plasma-saturated and bacterial fatty acids, suggesting they consumed lower-quality food resources than conspecifics in less urban-impacted areas. Therefore, these juvenile nurse sharks may already be under environmental stresses that could affect their long-term health and ability to respond physiologically to capture stress, which may pose a greater threat to these animals than previously believed. ...
Nurse sharks (Ginglymostoma cirratum), especially juveniles, are often encountered by near-shore and shore-based recreational anglers and are suggested to exhibit minimal behavioral and physiological responses to capture, largely based on studies of adults using commercial or scientific fishing methods. To quantify the sub-lethal effects of recreational angling on juvenile nurse sharks, 27 individuals (across 31 angling events) were caught using hook-and-line fishing methods. Over a 30-min period, 4 blood samples were taken with variable time intervals between sampling (i.e., randomized ordering of an interval of 5, 10, and 15 min between each sampling event). Lactate increased by 611% (6.7 ± 2.17 mmol/L) on average over the 30-min fight, and significant relationships were identified between lactate and blood draw number, fight time, and temperature, with large effect sizes. Significant relationships were also detected between blood draw number, glucose, and hematocrit, while osmolality was only affected by fishing site. These results suggest juvenile nurse sharks may exhibit a greater physiological stress response when exposed to recreational angling than adults captured with other fishing methods.
... Spending extended periods in coastal waters in a highly urbanized area may subject sharks to sewage effluent, chemical pollution (e.g., heavy metals, pesticides), and noise pollution [29,30]. Research from Florida found juvenile nurse sharks (Ginglymostoma cirratum) exhibit lower levels of omega-6 highly unsaturated fatty acids and higher levels of both saturated and bacterial fatty acids as a result of proximity to urbanized areas [31]. Another study [32] from Florida suggests that the high numbers of infertility in bonnethead sharks (Sphyrna tiburo) in Tampa Bay may be linked to exposure to organochlorine contaminants. ...
Global warming raises seawater temperatures and creates changes which have been found to affect the movement of large migrating marine species. Understanding the thermal niches of marine species could prove essential to anticipate how the future climate will alter migrations, and how conservation efforts will have to change accordingly. Orot Rabin power station in Hadera, Israel uses seawater to cool its turbine and releases the warm water back into the Mediterranean Sea. As a result, a marine area with artificially elevated temperatures is created around the effluent. Every winter in the past two decades, this area attracts sharks of two species, Carcharhinus obscurus and Carcharhinus plumbeus, presumably to spend the cold months at a higher temperature. This study concentrated on this point of artificial heat dissipation, which maintains a wide gradient of surface temperatures and allowed us to examine the temperature preferences of these species when given a larger range than what is naturally found in the sea. Between 2016 and 2018, 16 sharks were tagged with acoustic tags, 3 of which had temperature sensors, and 2 were additionally tagged with pop-up archival tags also logging temperature data. Results show that the sharks stayed in the elevated temperature, while the ambient sea was cold during the winter, spending several months in the heated area. Both species displayed a similar preferred range, spending 90 percent of their time at a temperature between 21.8 • C and 26.1 • C while the surrounding sea was 15.5-25.5 • C. Considering this chosen thermal niche and the rise in water temperature, it appears that for the past 40 years, the Eastern shores of the Mediterranean have become more suitable for these species, especially during transitional seasons. The question that arises, however, is whether these shark populations will benefit from the expanding range of preferable temperatures, or whether their proximity to shorelines will put them at greater risk in terms of human activities such as fishing and pollution. Key Contribution: Seasonal aggregations of Carcharhinid sharks are driven by a thermoregulatory behavior in which sharks remain within a specific range of temperatures. These findings provide valuable insights as to mechanisms that form these unique aggregations, and to further study the behavior and distribution of these species under global warning scenarios.
... The Atlantic nurse shark Ginglymostoma cirratum (Bonnaterre, 1788) inhabits the consolidated substrates of coastal and island waters of tropical and subtropical regions of the Atlantic Ocean, in which the species feeds on fish and invertebrates (Castro, 2000;Ebert et al., 2021;Garla et al., 2009). This shark is listed as vulnerable by the IUCN and Brazilian Red List (MMA, 2022), especially due to artisanal captures without management and the degradation of coral and rocky reefs (Carlson et al., 2021;Garla et al., 2015;Hammerschlag et al., 2016;ICMBio, 2018;Rangel et al., 2021;Wosnick et al., 2021). ...
In this study the authors use the Fishers ecological knowledge (FEK) from the south coast of the São Paulo State, in southeastern Brazil, to recover records of Atlantic nurse shark (Ginglymostoma cirratum), a threatened with extinction species, in a mosaic of marine‐protected areas (MPAs) of the south coast of São Paulo, in southeastern Brazil, in the southernmost distribution of the species in the Southwest Atlantic Ocean. For half a century, in the study area only one male of G. cirratum was officially recorded, in 1967. Retrieving records from artisanal fishers, recreational anglers, fishing guides and spearfishers added 30 more records of G. cirratum, including 2 recent captures (February/2022 and May/2022), especially around coastal islands that are covered by MPAs. Two uncommon fishing techniques, but which provided the highest number of records for the species, were documented. These are fishing nets and small longlines adapted for fishing close to the rocks, being an apparently traditional activity of a few natives of the region. As Brazil has a long history of intense catches of threatened elasmobranchs and problems with fisheries monitoring, the consideration of the FEK in the fisheries monitoring carried out by the authorities can be useful to promote improvements in data collection, especially of rare and endangered species such as G. cirratum. The strengthening of the protection of the MPAs and the articulation of research and management institutions with native people and tourists who use these areas should also be considered.
... Moreover, given that some of the immature nurse sharks were captured close to urbanized areas, higher proportions of bacterial markers maybe related to anthropogenic influence, such as the eutrophication process and increased production of organic materials (e.g. Le Moal et al. 2019;Rangel et al., 2021b). Other biomarkers, such as the DHA, were the most abundant PUFA in both nurse and blacktip sharks across all reproductive stages, suggesting a greater dependency on marine food webs based on dinoflagellates (Dalsgaard et al. 2003). ...
Energetic condition is one of the most important factors that influence fitness and reproductive performance in vertebrates. Yet, we lack evidence on how energetic states change in response to reproduction in large marine vertebrates. In the present study, we used a non-lethal approach to assess relationships among reproductive stage, circulating steroid hormones (testosterone and relative corticosteroid levels), plasma fatty acids, and the ketone body β-hydroxybutyrate in male sharks of two species with divergent ecologies, the benthic nurse shark (Ginglymostoma cirratum) and the epipelagic blacktip shark (Carcharhinus limbatus). We found higher relative corticosteroid levels in adult nurse sharks during the pre-mating period and in blacktip sharks during the mating period. Higher levels of β-hydroxybutyrate were found in adult nurse sharks during the mating period, but concentrations of this ketone body did not significantly vary across reproductive stages in blacktip sharks. We also detected reduced percentages of essential fatty acids during the mating period of both nurse and blacktip sharks. Taken together, our findings suggest that nurse and blacktip sharks differ in their energetic strategy to support reproduction, however, they likely rely on physiologically important fatty acids during mating, to support spermatogenesis.
... Benthic habitats across the archipelago have undergone dramatic transformations, including shifts in the dominant reef builders as well as decreased coral cover, due to deteriorating water quality, disease, bleaching, deep water hypoxia, and hydrological change (22,27,35,37,60)-a pattern of degradation documented across the greater Caribbean (13,61). These anthropogenic disturbances, in turn, could have degraded habitat for both sharks and their prey, in addition to lowering prey nutritional quality (62). This habitat loss was compounded by the intensification of fish and invertebrate harvesting in the 1970s (53), which likely reduced available prey for all sharks. ...
Significance
How abundant were sharks on Caribbean coral reefs before human impact? To explore this question, we recovered fossilized shark dermal denticles (scales) from a ∼7,000-y-old reef in western Caribbean Panama and compared them with denticles found on modern reefs in the same area. Our data suggest that sharks were over three times more numerous before humans began using marine resources in the area and that shark communities were compositionally different in the past, containing a higher proportion of fast-swimming, pelagic sharks. This reconstruction of preexploitation shark communities using fossil denticle assemblages demonstrates their potential to help contextualize recent declines in shark abundance, examine the ecological consequences of those declines, and guide shark management.
Dada a elevada diversidade nas estratégias de história de vida, os elasmobrânquios (tubarões e raias) tornam-se interessantes modelos para o estudo de relações entre a fisiologia e interações ecológicas no ambiente marinho. Embora os esforços para a conservação dos elasmobrânquios, que é atualmente o segundo grupo de vertebrados mais ameaçado do planeta, tenha estimulado um aumento no número de estudos sobre os padrões ecológicos e impactos antrópicos, pouco ainda se sabe sobre sua fisiologia. Assim, nesta tese de doutorado foram investigadas as variações fisiológicas sazonais e espaciais associadas ao estágio de vida e comportamento de tubarões de diferentes histórias de vida, utilizando múltiplas ferramentas não-letais para fornecer uma melhor compreensão dos padrões energéticos e reprodutivos, além de uma base fisiológica que ajude a prever os efeitos de distúrbios ambientais nos tubarões. O capítulo 1 aborda as variações inter- e intraespecíficas na ecologia nutricional de tubarões de diferentes estratégias de história de vida em um sistema insular oceânico protegido, o Arquipélago de Fernando de Noronha. Foram abordados também as variações nos padrões de dieta e condição nutricional e metabólica relacionados à reprodução de fêmeas de tubarões-tigre Galeocerdo cuvier (capítulo 2) e machos de tubarões-lixa Ginglymostoma cirratum e tubarões-galha-preta Carcharhinus limbatus (capítulo 3). Os capítulos 4, 5 e 6 abordam os efeitos da vida urbana na condição nutricional e padrões alimentares de tubarões com diferentes estilos de vida, o tubarão-lixa, o tubarão-galha-preta e o tubarão-tigre, respectivamente. Os resultados mostraram que a influência da urbanização na qualidade da dieta dos tubarões parece ser mais pronunciada em espécies sedentárias, como o tubarão-lixa, quando comparado com espécies mais ativas. Por fim, o capítulo 7 trouxe uma abordagem inédita na pesquisa de tubarões, combinando múltiplos marcadores fisiológicos com informações obtidas através de ultrassonografia e da telemetria acústica passiva para entender relações entre os aspectos fisiológicos e comportamentais de tubarões-tigre expostos ao turismo de alimentação. Os resultados demonstraram que o estágio de vida, a regulação endócrina e a condição nutricional influenciam e/ou são influenciadas pelo tempo que os tubarões passam interagindo com o turismo de alimentação. Em conjunto, os resultados mostraram que os biomarcadores nutricionais, reprodutivos e metabólicos utilizados nesta tese fornecem uma poderosa ferramenta para descrever padrões ecológicos complexos dos tubarões, especialmente quando combinados com outras tecnologias para rastreamento da movimentação e identificação do estágio reprodutivo dos tubarões.
It is common to see some wild animals in the city, like squirrels and raccoons, but have you ever thought about sharks in the city? While you will not see a shark hanging out on the streets of downtown, you may see one swimming along the shorelines of major seaside cities! Although living in coastal cities can bring many benefits to sharks, such as abundant food and protection from large predators, sharks can be negatively affected by pollution and fishing. We studied blacktip sharks living near the city of Miami, Florida, to see if urban living affected their diets and their health. We found that blacktip sharks living close the city (nicknamed urban sharks) were fatter than non-urban sharks. Urban sharks also showed signs of eating more saturated fats, which are unhealthy when in excess in an animal’s body. This shows us that urban sharks are likely eating more food of lower quality, which can have negative consequences for their health.
The way an animal utilizes and stores energy directly affects its ability to perform essential life functions (e.g. foraging, migration, reproduction), with implications for its health and fitness; therefore, individual variation in energy storage and metabolism within a population leads to intra-population variation in individual fitness and survival. Consequently, understanding the factors that contribute to variation in energy storage and metabolism within a population can aid in identifying factors that influence that population’s fitness. Compared to other taxa, there has been relatively little research to investigate the factors that govern variation in elasmobranch energy use and storage, particularly in wild populations. Furthermore, there has been almost no research conducted to explore how urbanization, a growing threat to marine ecosystems and organisms, affects elasmobranch energy storage and metabolism and, ultimately, their health and fitness. To address this knowledge gap, morphological (i.e. body condition) and biochemical (i.e. plasma cholesterol, free fatty acid, triglyceride, and ketone body concentrations) metrics related to energy storage and utilization were measured for 118 wild-sampled south Florida nurse sharks (Ginglymostoma cirratum). Statistical analyses were performed to identify any correlations between metrics and explore ontogenetic, sexual, seasonal, and spatial variation in body condition and plasma metabolite concentrations within the population. Results demonstrated that several metrics can be significantly linearly correlated with one another, but these relationships are highly dependent on nurse shark life stage and sex. The mean plasma metabolite concentrations for immature, mature female, and mature male nurse sharks was not significantly different; however, mature female nurse sharks had significantly higher body condition than mature male sharks. Further analysis revealed that this difference is driven by seasonal variation in mature female body condition, likely related to the accumulation of energy stores prior to reproduction. Significant seasonal variation also occurred in plasma concentrations of β-hydroxybutyric acid for mature male nurse sharks, possibly related to energetically exhausting mating activity during the wet season. Significant spatial variation occurred in the plasma concentrations of both triglycerides and free fatty acids for immature nurse sharks. Immature nurse sharks sampled within the more urbanized Metropolitan zone had higher mean triglyceride concentrations, and lower mean free fatty acid concentrations, than their conspecifics sampled within the relatively more natural National Park zone; this may imply that nurse sharks in the Metropolitan zone are feeding more, or more frequently, than nurse sharks in the National Park zone. The results of this thesis contribute to the growing knowledge base on energy storage and metabolism in wild-sampled elasmobranchs, as well as provide the first exploration of variation in elasmobranch body condition and plasma metabolites relative to urbanization, an anthropogenic threat with the capacity to influence elasmobranch fitness and survival.
Suspended sediments (SSs) were examined regarding the content of fatty acids (FAs) to associate them with sources of soil entry into the river. The source of organic matter was traced through fatty acid distribution, as well as erosion. Also, TOC, TN, and TOC/NT were used to support the results of FAs. For this, a tropical river was chosen to understand the main source of input considering the level of land occupation along the river. The Barigui river, in southern Brazil, was segmented in four distinct areas regarding the soil occupation (P1, P2, P3, and P4). Nine sampling campaigns were conducted from Nov/2014 to Nov/2015 using a time-integrated sampler. Site P1 has the lowest level of urbanization and showed the lowest concentration of FAs (16.35 μg⁻¹). In contrast, site P4, the most urbanized, showed the highest content of fatty acids, including those associated with erosion, 378.53 μg g⁻¹, specifically those with long chains. The mean concentrations of the saturated fatty acids (FAs) was 283.40 μg g⁻¹, monounsaturated fatty acids (MUFAs) was 79.46 μg g⁻¹, and polyunsaturated fatty acids (PUFAs) was 15.66 μg g⁻¹. Twenty-seven fatty acids were examined, nevertheless C15:0, C16:0, C18:0, and C18:1ω9 prevailed in all samples. Generally, those acids indicate sewage inputs. Statics analyses were used to find the relation between the source of organic matter (autochthonous, allochthones, and anthropogenic) and FAs. Finally, the input of organic matter is associated with land occupation, which can be distinguished by FA distribution.
Anthropogenic eutrophication threatens numerous aquatic ecosystems across the globe. Proactive management that prevents a system from becoming eutrophied is more effective and cheaper than restoring a eutrophic system, but detecting early warning signs and problematic nutrient sources in a relatively healthy system can be difficult. The goal of this study was to investigate if rates of change in chlorophyll a and nutrient concentrations at individual stations can be used to identify specific areas that need to be targeted for management. Biscayne Bay is a coastal embayment in southeast Florida with primarily adequate water quality that has experienced rapid human population growth over the last century. Water quality data collected at 48 stations throughout Biscayne Bay over a 20-year period (1995-2014) were examined to identify any water quality trends associated with eutrophication. Chlorophyll a and phosphate concentrations have increased throughout Biscayne Bay, which is a primary indicator of eutrophication. Moreover, chlorophyll a concentrations throughout the northern area, where circulation is restricted, and in nearshore areas of central Biscayne Bay are increasing at a higher rate compared to the rest of the Bay. This suggests increases in chlorophyll a are due to local nutrient sources from the watershed. These areas are also where recent seagrass die-offs have occurred, suggesting an urgent need for management intervention. This is in contrast with the state of Florida listing of Biscayne Bay as a medium priority impaired body of water.
Human population density within 100 km of the sea is approximately three times higher than the global average. People in this zone are concentrated in coastal cities that are hubs for transport and trade – which transform the marine environment. Here, we review the impacts of three interacting drivers of marine urbanization (resource exploitation, pollution pathways and ocean sprawl) and discuss key characteristics that are symptomatic of urban marine ecosystems. Current evidence suggests these systems comprise spatially heterogeneous mosaics with respect to artificial structures, pollutants and community composition, while also undergoing biotic homogenization over time. Urban marine ecosystem dynamics are often influenced by several commonly observed patterns and processes, including the loss of foundation species, changes in biodiversity and productivity, and the establishment of novel assemblages, ruderal species and synanthropes. Further, we discuss potential urban acclimatization and adaptation among marine taxa, interactive effects of climate change and marine urbanization, and ecological engineering strategies for enhancing urban marine ecosystems. By assimilating research findings across disparate disciplines, we aim to build the groundwork for urban marine ecology – a nascent field; we also discuss research challenges and future directions for this new field as it advances and matures. Ultimately, all sides of coastal city design: architecture, urban planning, and civil and municipal engineering, will need to prioritize the marine environment if negative effects of urbanization are to be minimized. In particular, planning strategies that account for the interactive effects of urban drivers and accommodate complex system dynamics could enhance the ecological and human functions of future urban marine ecosystems.
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The use of fatty acid (FA) tracers is a growing tool in trophic ecology, yet FA profiles are driven by a number of abiotic and biotic parameters, making interpretation and appropriate use confusing for ecologists.
We undertook a global analysis, compiling FA profiles of 106 chondrichthyan (shark, ray and chimaera) populations, as a model to test the utility of FA profiles to partition a priori trophic guilds, phylogeny, water temperature and habitats. Individual FAs characterizing these four factors were identified, promoting the use of these FAs as ecological tracers across taxa.
Habitat type was linked to five FAs: 16:0, 18:0 and biologically essential 22:6ω3 (indicative of the deep sea), 20:5ω3 (non‐complex demersal and deep‐sea demersal) and 20:4ω6 (reef and brackish water). Temperature was a key driver of four FAs (22:5ω6, 22:4ω6, 20:1ω9 and 20:5ω3), while trophic guild and phylogeny were important drivers of two pairs of FA tracers (18:0 and 20:5ω3; 20:1ω9 and 18:1ω9, respectively).
This analysis provides a novel understanding of the biological and ecological information that can be inferred from FA profiles and further validates the use of FAs as tracers to investigate the trophic ecology of chondrichthyans.
Future research should prioritize ex situ studies to further disentangle the influence of factors across taxa and tissue types, quantify biomodification, enabling the use of quantitative methods for diet determination and further develop ‘FATscapes’ to elucidate fine‐scale trophic geography and climate variability. Additionally, the creation of a taxonomically inclusive FA data repository will enable further meta‐analyses.
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• Fatty acids are essential to macroinvertebrate growth and reproduction and can indicate food web structure and nutritional quality of basal resources. However, broad‐scale examinations of how catchment land cover and associated stressors affect the proportions of fatty acids (FAs) in stream food webs are few.
• Here, we: (1) examine relationships among proportions of FAs among benthic periphyton and macroinvertebrate collector/gatherers, shredders, and predators; and (2) test if relationships between periphytic and macroinvertebrate FAs were altered due to the intensity of urban development in catchments.
• Proportions of the ≥20‐C eicosapentaenoic acid (EPA 20:5ω3), arachidonic acid (ARA 20:4ω6), and docosahexaenoic acid (22:6ω3) indicated collector/gatherers had a diet richer in periphyton than in shredders, which had significantly lower proportions of these FAs. Collector/gatherers were in turn likely to be high‐quality sources of ω3 and ≥ 20‐C FAs for predators, which also had significantly greater EPA and ARA proportions than those in shredders. Linoleic (18:2ω6) and α‐linolenic acid (18:3ω3) comprised the greatest proportions of FAs in shredders, which suggested a diet dominated by leaf litter and associated hyphomycetes.
• As catchment urbanisation increased, proportions of total ω3 FAs and EPA in periphyton were significantly greater. This pattern also was seen through macroinvertebrate consumers and predators, given that proportions of these FAs in macroinvertebrates also were significantly correlated with factors associated with catchment urbanisation. The significant increase in total ω3 FAs and EPA proportions within shredders indicated that periphyton growth, and their FAs, increased on leaf litter, probably due to greater nutrient concentrations associated with catchment urbanisation. Proportions of total ω6 FAs in biota were not significantly correlated with factors associated with urban development, which could indicate that they were of sufficient abundance for consumers regardless of urban intensity or possible changes in their sources.
• Our study provides an informative first step that identified notable differences in proportions of FAs among macroinvertebrates in urban streams and an increase in proportions of total ω3 FAs and EPA in periphyton, consumers, and predators as catchment urbanisation increases. Identifying how FA relationships within food webs change in response to catchment alterations and stressors could inform land use and management decisions by linking environmental changes to measures important to ecosystem outcomes.
Rapid urbanization has become an area of crucial concern in conservation owing to the radical changes in habitat structure and loss of species engendered by urban and suburban development. Here, we draw on recent mechanistic ecological studies to argue that, in addition to altered habitat structure, three major processes contribute to the patterns of reduced species diversity and elevated abundance of many species in urban environments. These activities, in turn, lead to changes in animal behavior, morphology and genetics, as well as in selection pressures on animals and plants. Thus, the key to understanding urban patterns is to balance studying processes at the individual level with an integrated examination of environmental forces at the ecosystem scale.
For over a century, physiological tools and techniques have been allowing researchers to characterize how organisms respond to changes in their natural environment and how they interact with human activities or infrastructure. Over time, many of these techniques have become part of the conservation physiology toolbox, which is used to monitor, predict, conserve, and restore plant and animal populations under threat. Here, we provide a summary of the tools that currently comprise the conservation physiology toolbox. By assessing patterns in articles that have been published in 'Conservation Physiology' over the past 5 years that focus on introducing, refining and validating tools, we provide an overview of where researchers are placing emphasis in terms of taxa and physiological sub-disciplines. Although there is certainly diversity across the toolbox, metrics of stress physiology (particularly glucocorticoids) and studies focusing on mammals have garnered the greatest attention, with both comprising the majority of publications (>45%). We also summarize the types of validations that are actively being completed, including those related to logistics (sample collection, storage and processing), interpretation of variation in physiological traits and relevance for conservation science. Finally, we provide recommendations for future tool refinement, with suggestions for: (i) improving our understanding of the applicability of glucocorticoid physiology; (ii) linking multiple physiological and non-physiological tools; (iii) establishing a framework for plant conservation physiology; (iv) assessing links between environmental disturbance, physiology and fitness; (v) appreciating opportunities for validations in under-represented taxa; and (vi) emphasizing tool validation as a core component of research programmes. Overall, we are confident that conservation physiology will continue to increase its applicability to more taxa, develop more non-invasive techniques, delineate where limitations exist, and identify the contexts necessary for interpretation in captivity and the wild.
Over the last century, humans have modified landscapes, generated pollution, and provided opportunities for exotic species to invade areas where they did not evolve. In addition, humans now interact with animals in a growing number of ways (e.g., ecotourism). As a result, the quality (i.e., nutrient composition) and quantity (i.e., food availability) of dietary items consumed by wildlife have, in many cases, changed. We present representative examples of the extent to which vertebrate foraging behavior, food availability (quantity and quality) and digestive physiology have been modified due to human-induced environmental changes and human activities. We find that these effects can be quite extensive, especially as a result of pollution and human-provisioned food sources (despite good intentions). We also discuss the role of nutrition in conservation practices, from the perspective of both in situ and ex situ conservation. Though we find that the changes in the nutritional ecology and physiology of wildlife due to human alterations are typically negative and largely involve impacts on foraging behavior and food availability, the extent to which these will affect the fitness of organisms and result in evolutionary changes is not clearly understood, and requires further investigation.
The movement and activity patterns of the nurse shark, Ginglymostoma cirratum , a vulnerable species off Brazil, were investigated using mark-recapture and acoustic telemetry at an oceanic insular Marine Protected Area, the Fernando de Noronha Archipelago, Brazil. A total of 93 sharks were captured and tagged, ranging from 82 to 265 cm of total length (TL). Nurse sharks were captured throughout the year, and all life-stages used the insular shelf. Fifteen sharks (16% of the total) were recaptured after periods at liberty ranging from 3.5 h to 705 days, and the distances between tag and recapture locations ranged from 0.07 to 3.5 km. Site fidelity and movements of 10 sharks ranging from 107 to 265 cm TL were investigated for 18 months with an array of automated telemetry receivers. The mean period of detection of the monitored sharks was 66 days, ranging from 13 to 119 days. One individual 158 cm TL was monitored with active tracking for 17 days, with distances between daily locations ranging from 0.84 to 3.32 km, exhibiting movements similar to those of sharks monitored by automated telemetry. Despite remaining motionless or exhibiting short range movements for several hours or days, nurse sharks can be relatively wide-ranging, and protected areas alone cannot be the only conservation measure used to protect this species, which requires a set of protective measures, including fisheries management.
Sharks have greater risk for bioaccumulation of marine toxins and mercury (Hg), because they are long-lived predators. Shark fins and cartilage also contain β-N-methylamino-l-alanine (BMAA), a ubiquitous cyanobacterial toxin linked to neurodegenerative diseases. Today, a significant number of shark species have found their way onto the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. Many species of large sharks are threatened with extinction due in part to the growing high demand for shark fin soup and, to a lesser extent, for shark meat and cartilage products. Recent studies suggest that the consumption of shark parts may be a route to human exposure of marine toxins. Here, we investigated BMAA and Hg concentrations in fins and muscles sampled in ten species of sharks from the South Atlantic and Pacific Oceans. BMAA was detected in all shark species with only seven of the 55 samples analyzed testing below the limit of detection of the assay. Hg concentrations measured in fins and muscle samples from the 10 species ranged from 0.05 to 13.23 ng/mg. These analytical test results suggest restricting human consumption of shark meat and fins due to the high frequency and co-occurrence of two synergistic environmental neurotoxic compounds.
Early-life nutrition is an important determinant of both short- and long-term performance and fitness. The avian embryo develops within an enclosed package of nutrients, of which fatty acids (FA) are essential for many aspects of development. The FA composition of yolk depends on maternal nutrition and condition prior to egg formation, which may be affected by the external environment. To test if maternal environment affects yolk FA composition, we investigated whether the FA composition of great tit (Parus major) egg yolks differed between urban and rural habitats, and between deciduous and coniferous habitats. The results reveal differences in FA composition between eggs laid in urban and rural habitats, but not between eggs from the coniferous and deciduous habitats. To a large extent, this difference likely reflects dietary differences associated with urban habitats rather than
dominating vegetation type. Specifically, urban yolks contained lower proportions of both ω-3 and ω-6 polyunsaturated FAs (PUFA), which are important for chick development. We also found a positive association between the proportion of saturated fatty acids and laying date, and a negative association between the proportion of ω-6 PUFA and clutch size. Given that urbanization is expanding rapidly, future studies should investigate whether factors such as anthropogenic food in the urban environment underlie these differences and whether they impair chick development.
Fatty acids (FA) have crucial functions in animals, affecting e.g., inflammatory responses, thermoregulation, and cell membrane fluidity. Diet and ambient temperature affect animals' FA composition, which, in turn, may influence these physiological processes. Great tits (Parus major)—common in both urban and rural habitats—are mainly granivorous during winter and insectivorous during summer. These diets show pronounced differences in FA composition. Such variation has context-dependent effects on physiology, because the thermal environment, food availability, and levels of pro-inflammatory environmental stressors differ between urban and rural areas. Thus, we investigated how great tit plasma FA composition varied between urban and rural habitats and across seasons. Eight FAs differed between urban and rural birds. Among these, arachidonic acid [omega (ω)-6 polyunsaturated FA] with thermoregulatory and pro-inflammatory properties was more abundant in urban than rural birds in winter, whereas ω-3 FAs with anti-inflammatory properties were more abundant in rural birds. The difference in pro- and anti-inflammatory FAs suggest that the negative health effects that urban birds suffer from being exposed to higher levels of pollutants might be enhanced by an elevated inflammatory response. Eight FAs differed between winter and summer birds. This variation reflected the diet change: FAs common in seeds, e.g., oleic- and linoleic acid, were present in higher amounts in winter birds, whereas ω-3 polyunsaturated FAs that are common in caterpillars were more abundant in summer birds. Overall, a larger seasonal variation was seen among the urban birds. This study is the first to reveal a difference in FA composition between urban and rural populations for all animals studied to date. Future experiments should unravel the physiological implications of this variation, and ultimately, link its effects to fitness of animals with different physiological and dietary requirements in urban and rural environments.
Globally, ecosystems and their constituent flora and fauna face the localized and broad-scale influence of human activities.
Conservation practitioners and environmental managers struggle to identify and mitigate threats, reverse species declines,
restore degraded ecosystems, and manage natural resources sustainably. Scientific research and evidence are increasingly regarded
as the foundation for new regulations, conservation actions, and management interventions. Conservation biologists and managers
have traditionally focused on the characteristics (e.g. abundance, structure, trends) of populations, species, communities,
and ecosystems, and simple indicators of the responses to environmental perturbations and other human activities. However,
an understanding of the specific mechanisms underlying conservation problems is becoming increasingly important for decision-making,
in part because physiological tools and knowledge are especially useful for developing cause-and-effect relationships, and
for identifying the optimal range of habitats and stressor thresholds for different organisms. When physiological knowledge
is incorporated into ecological models, it can improve predictions of organism responses to environmental change and provide
tools to support management decisions. Without such knowledge, we may be left with simple associations. ‘Conservation physiology’
has been defined previously with a focus on vertebrates, but here we redefine the concept universally, for application to
the diversity of taxa from microbes to plants, to animals, and to natural resources. We also consider ‘physiology’ in the
broadest possible terms; i.e. how an organism functions, and any associated mechanisms, from development to bioenergetics,
to environmental interactions, through to fitness. Moreover, we consider conservation physiology to include a wide range of
applications beyond assisting imperiled populations, and include, for example, the eradication of invasive species, refinement
of resource management strategies to minimize impacts, and evaluation of restoration plans. This concept of conservation physiology
emphasizes the basis, importance, and ecological relevance of physiological diversity at a variety of scales. Real advances
in conservation and resource management require integration and inter-disciplinarity. Conservation physiology and its suite
of tools and concepts is a key part of the evidence base needed to address pressing environmental challenges.
Fatty acids are a valuable tool in ecological studies because of the large number of unique structures synthesized. They provide versatile signatures that are being increasingly employed to delineate the transfer of dietary material through marine and terrestrial food webs. The standard procedure for determining fatty acids generally involves lipid extraction followed by methanolysis to produce methyl esters for analysis by gas chromatography. By directly transmethylating ~50 mg wet samples and adding an internal standard it was possible to greatly simplify the analytical methodology to enable rapid throughput of 20-40 fish tissue fatty acid analyses a day including instrumental analysis. This method was verified against the more traditional lipid methods using albacore tuna and great white shark muscle and liver samples, and it was shown to provide an estimate of sample dry mass, total lipid content, and a condition index. When large fatty acid data sets are generated in this way, multidimensional scaling, analysis of similarities, and similarity of percentages analysis can be used to define trophic connections among samples and to quantify them. These routines were used on albacore and skipjack tuna fatty acid data obtained by direct methylation coupled with literature values for krill. There were clear differences in fatty acid profiles among the species as well as spatial differences among albacore tuna sampled from different locations.
The study of animal behaviour is important for both ecology and ecotoxicology, yet research in these two fields is currently developing independently. Here, we synthesize the available knowledge on drug-induced behavioural alterations in fish, discuss potential ecological consequences and report results from an experiment in whichwe quantify both uptake and behavioural impact of a psychiatric drug on a predatory fish (Perca fluviatilis) and its invertebrate prey (Coenagrion hastulatum). We show that perch became more active while damselfly behaviour was unaffected, illustrating that behavioural effects of pharmaceuticals can differ between species. Furthermore, we demonstrate that prey consumption can be an important exposure route as on average 46% of the pharmaceutical in ingested prey accumulated in the predator. This suggests that investigations of exposure through bioconcentration, where trophic interactions and subsequent bioaccumulation of exposed individuals are ignored, underestimate exposure. Wildlife may therefore be exposed to higher levels of behaviourally altering pharmaceuticals than predictions based on commonly used exposure assays and pharmaceutical concentrations found in environmental monitoring programmes.
Bull Sharks Carcharhinus leucas in the Indian River Lagoon, Florida, have been documented to frequently occur in human‐altered habitats, including dredged creeks and channels, boat marinas, and power plant outfalls. The purpose of this study was to examine the short‐term movements of age‐0 and juvenile Bull Sharks to quantify the extent to which those movements occur in altered habitats. A total of 16 short‐term active acoustic tracks (2–26 h) were carried out with 9 individuals, and a 10th individual was fitted with a long‐term coded transmitter for passive monitoring by fixed listening stations. Movement and activity space statistics indicated high levels of area reuse over the span of tracking (hours to days). All but one shark used
altered habitat at some point during tracking, such that 51% of all tracking positions occurred in some type of altered habitat. Of the sharks that used altered habitat, the mean (±1 SD) percent of positions within altered habitat was 66 (±40)%. Furthermore, tracks for 3 individuals indicated selection for altered habitats. The single passively monitored Bull Shark was detected in power plant outfalls almost daily over a 5‐month period, providing the first indication of longer‐term fidelity to thermal effluents. Use of one dredged creek was influenced by local salinity, the tracked sharks dispersing from the altered habitat when salinity declined. The affinity of young Bull Sharks to altered habitats in this system could help explain their reported accumulation of a variety of harmful contaminants, which could negatively affect their health and survival.
Received July 27, 2012; accepted November 28, 2012
Lipids are major sources of metabolic energy in sharks and are closely linked to environmental conditions and biological cycles, such as those related to diet, reproduction and migration. In this study, we report for the first time, the total lipid content, lipid class composition and fatty acid profiles of muscle and liver tissue of white sharks, Carcharodon carcharias, of various lengths (1.5-3.9 m), sampled at two geographically separate areas off southern and eastern Australia. Muscle tissue was low in total lipid content (<0.9% wet mass, wm) and was dominated by phospholipids (>90% of total lipid) and polyunsaturated fatty acids (34±12% of total fatty acids). In contrast, liver was high in total lipid which varied between 51-81% wm and was dominated by triacylglycerols (>93%) and monounsaturated fatty acids (36±12%). With knowledge of total lipid and dry tissue mass, we estimated the energy density of muscle (18.4±0.1 kJ g-1 dm) and liver (34.1±3.2 kJ g-1 dm), demonstrating that white sharks have very high energetic requirements. High among-individual variation in these biochemical parameters and related trophic markers were observed, but were not related to any one biological or environmental factor. Signature fatty acid profiles suggest that white sharks over the size range examined are generalist predators with fish, elasmobranchs and mammalian blubber all contributing to the diet. The ecological applications and physiological influences of lipids in white sharks are discussed along with recommendations for future research, including the use of non-lethal sampling to examine the nutritional condition, energetics and dietary relationships among and between individuals. Such knowledge is fundamental to better understand the implications of environmental perturbations on this iconic and threatened species.
Fatty acid profile analysis is a tool for dietary investigation that may complement traditional stomach contents analysis. While recent studies have shown that the liver of sharks fed different diets have differing fatty acid profiles, the degree to which diet is reflected in shark blood serum and muscle tissue is still poorly understood. An 18-week controlled feeding experiment was undertaken using captive Port Jackson sharks (Heterodontus portusjacksoni). Sharks were fed exclusive diets of artificial pellets treated with fish or poultry oil and sampled every 6 weeks. The fatty acid profiles from liver, blood serum, and muscle were affected differently, with the period from which significant differences were observed varying by tissue and diet type. The total fatty acid profiles of fish oil and poultry oil fed sharks were significantly different from week 12 onwards in the liver and blood serum, but significant differences were only observed by week 18 in the muscle tissue of sharks fed different diets. The drivers of dissimilarity which aligned with dietary input were 14:0, 18:2n-6, 20:5n-3, 18:1n-9 and 22:6n-3 in the liver and blood serum. Dietary fatty acids accumulated more consistently in the liver than in the blood plasma or muscle, likely due to its role as the central organ for fat processing and storage. Blood serum and muscle fatty acid profiles were influenced by diet, but fluctuated over-time. The low level of correlation between diet and muscle FA profiles is likely a result of low levels of fat (<1 %) in the muscle and the domination of structural, cell-membrane phospholipids in shark muscle tissues. Our findings describe inter-tissue differences in the incorporation of fatty acids from the diet to consumer, which should be taken into account when interpreting dietary patterns from fatty acid profiles.
A comprehensive, but simple-to-use software package for executing a range of standard numerical analysis and operations used in quantitative paleontology has been developed. The program, called PAST (PAleontological STatistics), runs on standard Windows computers and is available free of charge. PAST integrates spreadsheettype data entry with univariate and multivariate statistics, curve fitting, time-series analysis, data plotting, and simple phylogenetic analysis. Many of the functions are specific to paleontology and ecology, and these functions are not found in standard, more extensive, statistical packages. PAST also includes fourteen case studies (data files and exercises) illustrating use of the program for paleontological problems, making it a complete educational package for courses in quantitative methods.
A 14 mo trawl survey was conducted at 8 study sites in Biscayne Bay, Florida, USA, to compare the species composition and structure of juvenile fish assemblages found near the mouths of freshwater flood control canals with those in similar areas with relatively stable salinity regimes. Water temperature, salinity, dissolved oxygen and depth measurements were recorded during fish sampling and bottom vegetation was also quantified. The survey yielded a total of 38134 individuals from 95 taxa. Fish species composition was similar among sites, but more species were collected from stable-versus variable-salinity areas. Mean fish abundance and the mean abundances of Eucinostomus gula, Lagodon rhomboides, Opsanus beta and Lutjanus griseus shared a general pattern of increase from north to south, with highest values occurring at one or more of the canal-influenced sites. In contrast, mean species richness and the mean abundances of Lucania parva, Haemulon sciurus, H. plumieri, and H. parra were significantly greater at stable-salinity sites than at variable-salinity sites. Freshwater challenge experiments were then conducted on each of the fishes above, as well as on 2 relatively uncommon species, Cynoscion nebulosus and Cyprinodon variegatus. The mortality of groups exposed to a single, rapid, freshwater pulse (i.e. salinity was changed from approximately 32 ppt to 0 to 32 ppt over 2 h) was compared with that of controls. Of the 8 fishes that dominated the nearshore habitats of Biscayne Bay, 5 exhibited no mortality and L. rhomboides, L. parva, and H. plumieri exhibited 12.5, 50 and 100% mortality rates, respectively. Mortality was 100% for the relatively uncommon C. nebulosus and C. variegatus. Results suggest that the differential osmoregulatory abilities of the species tested may underlie some, but not all, of the structural differences observed between fish assemblages from stable-salinity habitats versus those adjacent to freshwater canals.
LIRMAN, D.; DEANGELO, G.; SERAFY, J.E.; HAZRA, A.; HAZRA, D.S.; and BROWN, A., 2008. Geospatial video monitoring of nearshore benthic habitats of western Biscayne Bay (Florida) using the shallow-water positioning sys- tem (SWaPS). Journal of Coastal Research, 24(1A), 135-145. West Palm Beach (Florida), ISSN 0749-0208. The nearshore habitats of western Biscayne Bay, a shallow lagoon adjacent to the city of Miami, are influenced by salinity fluctuations caused by freshwater discharges from canals. Benthic communities in these susceptible littoral habitats have been underrepresented in monitoring programs because of the difficulties associated with boat access. In the present study, we implement a geospatial video-based survey technique, the shallow-water positioning system (SWaPS), to document the abundance and distribution of benthic organisms in these shallow habitats. Mounted on a shallow-draft vessel, SWaPS integrates a global positioning system receiver with a video camera such that each video frame recorded is stamped with position information, date, water depth, heading, and pitch and roll. The georeferenced digital frames collected can be easily analyzed to document patterns of abundance and distribution of submerged aquatic vegetation and other benthic organisms. The field surveys conducted using SWaPS showed that species distributions are influenced by their respective tolerances to salinity patterns. Seagrass species with relatively high tolerance for low, variable salinity (e.g., Halodule wrightii and Ruppia maritima) tend to have high abundance only in areas influenced directly by canal discharges, while species with relatively limited tolerance for low salinity (e.g., Thalassia testudinum) tend to increase in abun- dance with increasing distance from the mouths of canals. The use of video-based surveys with high spatial precision facilitates rapid, cost-effective, and repeatable monitoring of shallow marine benthic communities. The most attractive features of this system are (1) the ability to cover large areas rapidly without divers and (2) the ability to return to precise locations without establishing permanent markers (e.g., stakes). Moreover, the georeferenced digital images collected with SWaPS are a valuable permanent visual archive that can provide the baseline information needed to evaluate long-term patterns of change in environments such as western Biscayne Bay that are subject to increasing pressure from human activities.
Lipids and their constituent fatty acids are, along with proteins, the major organic constituents of fish, and they play major roles as sources of metabolic energy for growth including reproduction and movement, including migration. Furthermore, the fatty acids of fish lipids are rich in ω3 long chain, highly unsaturated fatty acids (n-3 HUFA) that have particularly important roles in animal nutrition, including fish and human nutrition, reflecting their roles in critical physiological processes. Indeed, fish are the most important food source of these vital nutrients for man. Thus, the longstanding interest in fish lipids stems from their abundance and their uniqueness. This review attempts to summarize our present state of knowledge of various aspects of the basic biochemistry, metabolism, and functions of fatty acids, and the lipids they constitute part of, in fish, seeking where possible to relate that understanding as much to fish in their natural environment as to farmed fish. In doing so, it highlights the areas that require investigation in greater depth and also the increasing application of molecular technologies in fish lipid metabolism, which will further fascilitate advances through molecular biological and genetic techniques, including genomics and proteomics.
Fatty acid (FA) analysis is a well-established tool for studying trophic interactions in marine habitats. However, its application to benthic food webs poses 2 particular challenges. First, unlike pelagic zooplankton, benthic consumers have access to different sizes and functional groups of primary producers and may consume a highly mixed diet. Classes of benthic primary producers are distinct in their overall FA composition, but most do not possess unique marker FAs that can be used to identify their contribution to higher trophic levels. Second, unlike mammalian predators, benthic invertebrates have the capacity to significantly modify their dietary FAs and thereby obscure markers for food sources. Controlled feeding studies have been used to distinguish dietary tracer FAs from those that are modified. by the consumer in several benthic invertebrates, but more such studies are needed. Despite these challenges, FAs have been used to study trophic structure in a variety of benthic habitats including the deep sea, polar regions, estuaries, and the rocky subtidal zone. However, the complexity of benthic food webs and lack of unique markers impose uncertainties in the interpretation of FA data from field studies. Multivariate analyses are necessary for analyzing FA datasets, although univariate tests can be useful for comparing levels of informative FAs among food sources and consumers. Combining FA analysis with other lines of evidence, such as stable isotope analysis, offers a more reliable approach to examining trophic interactions in benthic systems.
Cities may represent one of the most challenging environments for carnivorous mammals. For example, cities have a dearth of vegetation and other natural resources, coupled with increased habitat fragmentation and an abundance of roads as well as altered climate (e.g. temperature, light, rainfall and water runoff). It is therefore intriguing that several carnivore species have become established in cities across the globe. Medium-sized carnivores such as the red fox, coyote, Eurasian badger and raccoon not only survive in cities but also have managed to exploit anthropogenic food sources and shelter to their significant advantage, achieving higher population densities than are found under natural conditions. In addition, although they may not live permanently within cities, even large carni-vores such as bears, wolves and hyaenas derive significant benefit from living adjacent to urbanized areas. In this review, we examine the history of urban adaptation by mammalian carnivores, explore where they are living, what they eat, what kills them and the behavioural consequences of living in urban areas. We review the biology of urban carnivores, exploring traits such as body size and dietary flexibility. Finally, we consider the consequences of having populations of carnivores in urbanized areas, both for humans and for these charismatic mammals. In conclusion, in a time of massive environmental change across the globe, the continuing encroachment of urbanization upon wilderness areas is substantially reducing the availability of natural habitats for many species; therefore , understanding the biology of any taxon that is able to adapt to and exploit anthropogenically disturbed systems must aid us in both controlling and developing suitable conservation measures for the future of such species.
Throughout evolutionary history, elasmobranchs have developed diverse reproductive strategies. Little focused work, however, has addressed how neonatal nutritional state is affected by differing degrees of maternal investment associated with these markedly different reproductive strategies. To investigate the effect of maternal investment on the nutritional quality of pups during the early-life history of an extreme viviparous elasmobranch, quantitative biomarkers analysis including lipids, fatty acids and stable isotopes were conducted. Using the cownose ray, Rhinoptera bonasus (histotrophic viviparous) as a model, we found that pups were initially born in a positive nutritional state, enriched in physiologically important essential fatty acids and nitrogen and carbon stable isotopes values (δ15N and δ13C), a result of maternal intrauterine transfer. A systematic decrease in some fatty acids and δ15N values, as well as a decrease in cholesterol with growth, confirmed that these substrates were derived from maternal resources and used in initial metabolic processes following birth. An observed increase in condition factor, plasma essential fatty acids and triglycerides/cholesterol ratio with increasing young body identified a progression towards successful independent foraging with pups not displaying marked nutritional deficiency or fasting phases. Our multi tracer approach allowed the identification of two size classes of young rays (<50 cm and <70 cm disc width) that displayed distinct physiological states. Since prenatal maternal investment is critical for offspring condition and to promote successfully foraging post birth, understanding the trophic ecology and physiological state of pups during their first year are critical factors to guide management and conservation within nursery grounds.
Serum protein electrophoresis (EPH) is used to assess relative
concentrations of blood proteins in clinical and biological studies.
Serum EPH fractions have been determined for elasmobranchs using
mammalian albumin, alpha 1-, alpha 2-, beta-, and gamma-globulin
fractions, and have been deemed fractions 1 through 5, respectively.
However, serum EPH fraction concentration reference intervals
(RIs) have not been widely established for different elasmobranch
species. In this study, RIs for fractions 1 through 5 were determined
from 45 wild-caught Nurse Sharks Ginglymostoma cirratum (27
females and 23 males) in South Florida. Serum samples were isolated
from whole blood following caudal venipuncture. Body condition was
also measured in the field to assess the relative health of the individuals
sampled. There was no relationship between body condition and
serum EPH fraction concentrations. In addition, there was no difference
in body condition or serum EPH fraction concentrations
between females and males. Total solids and total protein values
were significantly different (P < 0.001). Nurse Shark serum EPH
fraction 1 was found within the mammalian albumin migrating band
distance and was negligible. Fraction 2 showed no peak in the mammalian
alpha 1-globulin range. A thin, medium peak in the mammalian
alpha 2-globulin range represented fraction 3. In the
mammalian beta-globulin range, fraction 4 consisted of the majority
of protein observed. It was represented by a smooth, broad peak. A
short, medium broad peak in the mammalian gamma-globulin range
represented fraction 5. The Nurse Shark serum EPH fraction RIs
provided in this study may be utilized to clinically evaluate the health
of Nurse Sharks in captivity and in the wild, and to compare the
health of their populations around the world experiencin
Previous research has identified similar trophic levels for a wide range of coral reef sharks and large teleost fishes but has been unable to resolve the extent of dietary overlap and resource sharing that lead to interpretation of functional roles and, hence, adequately describe interaction strengths in food webs. We used fatty acid (FA) profiles of muscle and plasma of several mesopredators reflecting diet to better understand the trophic structure and functioning of Great Barrier Reef ecosystems. Multivariate analysis identified significant dietary overlap between 2 shark species (whitetip reef sharks and grey reef sharks), but whitetip reef sharks occupied a smaller niche area than grey reef sharks. We also found clear niche separation between sharks and teleost fishes (red throat emperor, coral trout and grass emperor). All mesopredators sampled had high proportions of polyunsaturated FAs linking them to carnivory, but species differences suggest distinctive dietary sources from trophic biomarker ratios; one based on pelagic diatoms for sharks and flagellates and algae for teleost fishes. However, based on a degree of niche overlap of species sharing common diet, reef-dwelling teleost fishes such as coral trout also derive nutrients from pelagic environments. A faster analytical method to determine FA profiles, proven highly useful in tuna, was tested and deemed viable for muscle tissue of tropical teleost fishes and sharks, while questions remain for use of FA extraction of plasma in ecological studies. These results demonstrate that fine scale inter-specific differences in diet exist between mesopredators in coral reef ecosystems. Our results raise important questions about the ecological influences of these species and energy flow among mesopredators in coral reef ecosystems.
An 8-week nutritional experiment was conducted with the aim of evaluating the influences of different arachidonic acid (ARA) levels and two different temperatures (29.5 °C and 26.5 °C) on the growth performance, tissue and whole-body fatty acid (FA) compositions, plasma prostaglandin concentration, liver morphology and expression of genes related to lipid metabolism in cobia juveniles. A basal fat-reduced diet was manufactured and subsequently coated with different FA sources, distinct levels of ARA (ARA1, 0.5%; ARA2, 1.2%; and ARA3, 1.9%) and fish oil (FO: 8.8%, as a control diet). All diets were formulated to be isoproteic and isolipidic. Cobia juveniles (5.86 ± 0.40 g) were randomly divided into 24 tanks with 18 animals each. Twelve tanks were kept at 29.5 °C, and 12 tanks were kept at 26.5 °C. The animals were fed twice per day with each experimental diet until
apparent satiation in triplicate tanks at both temperatures. The results revealed that the animals maintained at 26.5 °C and fed with the ARA diets exhibited better growth than those fed with the FO diet and kept at 29.5 °C. In contrast to observations in other teleost species, ARA excess did not reduce growth or survival. The FA compositions of the livers, fillets and whole bodies generally reflected the diet compositions, i.e., gradual increases in ARA were observed according to the diet level. Additionally, greater depositions of docosahexaenoic acid (DHA) in the fillets of the animals from the ARA2 group that was kept at 26.5 °C were observed. The plasma prostaglandin levels were greater in the animals that were kept at 29.5 °C for all experimental diets and in the ARA2 animals compared with the FO groups at both temperatures. The FAS and SREBP-1 expressions in the livers were
down-regulated in the ARA1 and ARA2 animals that were maintained at 26.5 °C compared with the animals that were fed the same diets but kept at 29.5 °C. Additionally, SREBP-1 expression was up-regulated in the ARA2 animals compared with the FO animals at both temperatures. The results of this study indicated that ARA inclusion between 0.5 and 1.9% combined with a temperature of 26.5 °C can improve juvenile cobia growth performance and directly influence the modulation of prostaglandin synthesis and the relative expressions of
lipid genes.
Ecologists studying bird foraging ecology have generally focused on food quantity over quality. Emerging work suggests that food quality, in terms of highly unsaturated omega‐3 fatty acids (HUFA), can have equally important effects on performance. HUFA, which are present in aquatic primary producers, are all but absent in vascular plants, and HUFA content is also correspondingly higher in aquatic insects. Here, we show that Tree Swallow (Tachycineta bicolor) chicks rapidly accumulate HUFA from food during the nestling period. Using data sampled over 24 years, we also show that Tree Swallow breeding success is positively associated with the availability of HUFA‐rich aquatic insects. Variation in aquatic insect biomass during chick development was a strong predictor of fledging success, whereas variation in terrestrial insects had little effect on fledging success. Our results highlight the potential for nutritional mismatches between insectivores and high‐quality prey to affect avian reproductive performance.
The human population is rapidly urbanizing, and the negative impacts of urban cover on biodiversity and ecosystem function are expected to increase. Trophic dynamics have been hypothesized to change with urbanization, with consequences for biodiversity and function. Here, I review recent progress in this area by focusing on how urbanization affects dietary sources, trophic interactions and the functional ecology of synanthropic species.
Urbanization affects primary autochthonous production in terrestrial and aquatic ecosystems by replacing and fragmenting natural areas with impervious cover, increasing nutrient supply, changing hydrological regimes, and altering the composition and seasonality of primary producers. The responses of primary production differ between climatic regions or across hydrological regimes.
Urbanization can also change the availability of subsidies (autochthonous vs. allochthonous resources) because many urban species feed on human food (anthropogenic subsidies) and because of changes in the plant composition and physical characteristics of riparian zones.
Urbanization can change the composition of consumers by decreasing the abundance of apex predators, releasing mesopredators, as well as the introduction of non‐native omnivores.
Few direct experiments have been conducted on trophic interactions in urban ecosystems. They broadly suggest that urbanization weakens herbivory and predation, but that it might increase competition between synanthropic and urbanophobic species. However, the outcomes of these interactions are highly context‐specific.
The reliance of synanthropic species on anthropogenic subsidies appears to be an important aspect of urban trophic ecology. However, more research is needed to understand how dietary flexibility, especially in relation to anthropogenic subsidies, contributes to the physiology and population dynamics of synanthropes.
Urbanization can dramatically change trophic dynamics in the urban ecosystem with implications for biodiversity patterns, management and conservation. However, it is clear that a broader and more mechanistic understanding of the urban food webs is needed. This can be accomplished through inclusion of functional trophic metrics in monitoring efforts, the use of stable isotope food web metrics, the use of multi‐trophic‐level experiments and a more detailed study of the functional ecology of synanthropes.
A plain language summary is available for this article.
Migratory birds are physiologically specialized to accumulate massive fat stores (up to 50-60% of body mass), and to transport and oxidize fatty acids at very high rates to sustain flight for many hours or days. Target gene, protein and enzyme analyses and recent -omic studies of bird flight muscles confirm that high capacities for fatty acid uptake, cytosolic transport, and oxidation are consistent features that make fat-fueled migration possible. Augmented circulatory transport by lipoproteins is suggested by field data but has not been experimentally verified. Migratory bats have high aerobic capacity and fatty acid oxidation potential; however, endurance flight fueled by adipose-stored fat has not been demonstrated. Patterns of fattening and expression of muscle fatty acid transporters are inconsistent, and bats may partially fuel migratory flight with ingested nutrients. Changes in energy intake, digestive capacity, liver lipid metabolism and body temperature regulation may contribute to migratory fattening. Although control of appetite is similar in birds and mammals, neuroendocrine mechanisms regulating seasonal changes in fuel store set-points in migrants remain poorly understood. Triacylglycerol of birds and bats contains mostly 16 and 18 carbon fatty acids with variable amounts of 18:2n-6 and 18:3n-3 depending on diet. Unsaturation of fat converges near 70% during migration, and unsaturated fatty acids are preferentially mobilized and oxidized, making them good fuel. Twenty and 22 carbon n-3 and n-6 polyunsaturated fatty acids (PUFA) may affect membrane function and peroxisome proliferator-activated receptor signaling. However, evidence for dietary PUFA as doping agents in migratory birds is equivocal and requires further study.
The Comprehensive Everglades Restoration Plan (CERP) is intended to restore the Everglades ecosystem (FL, USA) by altering its hydrology, with likely consequences for “downstream” estuarine and marine communities in Florida Bay and the Florida Keys. Spiny lobsters (Panulirus argus) are among several species of special concern with respect to CERP because they are of economic and ecological importance and because their nursery habitat may be impacted. We used agent-based, spatially explicit modeling to evaluate the possible impacts of changing water quality (temperature, salinity, harmful algal blooms (HABs)) on spiny lobsters and sponges, the latter of which provide shelter for juvenile lobsters. In our simulations, lobster abundance declined 6–24% in scenarios where salinity either decreased alone or in combination with HABs that kill sponges and are associated with changing water quality. The most severe decline in lobsters occurred when salinity was lowest and HABs occurred annually. One third of this decline was attributable to decreased salinity that increased lobster mortality and movement. However, the greatest impacts on lobsters were indirect. CERP-associated changes in salinity along with HABs caused a die-off of large sponges, resulting in higher predatory mortality on lobsters that depend on sponges for shelter in hard bottom nursery habitats. Sponges declined by ∼50% in simulations with HABs, whereas decreased salinity alone led to sponge mortality of 9–18%. In contrast, higher temperatures increased juvenile lobster growth and eventual recruitment by approximately 7%. Our results suggest that returning Florida Bay to more estuarine, pre-development conditions is likely to result in an ecosystem reversal that is detrimental to stenohaline marine taxa, a scenario with significant socioeconomic implications.
Eutrophication results in a deficiency of n-3 LC-PUFA (long-chain polyunsaturated fatty acids) in aquatic food chains, affecting fish nutrition and physiology. The trophic transfer of FA (fatty acids) to fish species of different feeding habits was investigated in two reservoirs in southeast Brazil—the mesotrophic Ponte Nova Reservoir (PN) and the hypereutrophic Billings Reservoir (Bil). Total FA profile of stomach contents and adipose tissue, triacylglycerols (TAG), and phospholipids (PL) from liver and muscle of the omnivorous Astyanax fasciatus and the carnivorous Hoplias malabaricus were analyzed by gas chromatography. A prevalence of n-6PUFA, as 18:2n-6 (linoleic acid) and 20:4n-6 (arachidonic acid, ARA) was observed in the stomach contents and in the tissues of A. fasciatus from the PN reservoir. In contrast, n-3 LC-PUFA, as 20:5n-3 (eicosapentaenoic acid, EPA) was accumulated in fish tissues from Bil, resulting in higher n3/n6 and EPA/ARA ratios, compared to fish from PN. This differential FA accumulation was also observed for H. malabaricus, but differences were slightly minor, and no changes were observed in the EPA/ARA ratios between fish from both reservoirs. Regardless reservoir, FA profiles of TAG resembled that of their diet, whereas FA profiles of PL were more conservative and mainly comprised by LC-PUFA. We conclude that reservoir trophic status affected the FA composition of food resources available to these fish species, resulting in differential allocation of n-3 and n-6 FA. As expected, FA profile of the investigated fish species also reflected their feeding habit and physiological demands.
To estimate the impact of urbanization on wild animals, it is important to know how different species, populations and/or individuals deal with and respond to environmental stress. Are more urbanized species adapted to their environment, or do individuals acclimatize over the course of their life? Alternatively, do they simply cope at the expense of other functions? These are three key processes that I will address using two important physiological responses as case traits, namely oxidative stress and inflammation, – which are known to be under genetic control as well as showing great plasticity.
Oxidative stress is a state of more reactive oxidants than antioxidants, which may cause tissue damage linked to disease and senescence. Inflammation, on the other hand, is the response of vascular tissues to harmful stimuli. However, under progressive stimuli, inflammation may also cause tissue destruction and pathology.
Although patterns and strengths of effects are not always clear cut, the often interconnected oxidative stress and inflammation have the potential to be severely affected by urban stressors, thereby mechanistically linking ecology to fitness. Here I discuss five major urban stressors: chemical, noise and artificial night light pollution, disease and diet, and how their individual and combinatory effects may affect these two physiological responses.
To start to disentangle whether physiological responses are a question of evolving, acclimatizing or coping with the urban environment, population genetics along with regulatory mechanisms of gene expression will shed light on the ‘costs’ of urban life and help to understand why some species or genotypes thrive, while others are absent, in urban areas. Single nucleotide polymorphism ( SNP ) has been successful for explaining local adaptation and tolerance towards acute toxic substances. However, for multiple stressors acting in concert, at low chronic exposure, investigations of epigenetic mechanisms regulating gene expression may be more illuminating.
Here I review the pathways by which genetic and epigenetic mechanisms can affect oxidative stress and inflammatory responses in urban environments, thereby affecting overall fitness. By doing so, I identify the major outstanding gaps of knowledge in the interfaces between ecology, toxicology, evolutionary and molecular biology to inform future studies of urban wildlife.
The overexploitation of sharks has become a global environmental issue in need of a comprehensive and multifaceted management response. Tracking studies are beginning to elucidate how shark movements shape the internal dynamics and structure of populations, which determine the most appropriate scale of these management efforts. Tracked sharks frequently either remain in a restricted geographic area for an extended period of time (residency) or return to a previously resided-in area after making long-distance movements (site fidelity). Genetic studies have shown that some individuals of certain species preferentially return to their exact birthplaces (natal philopatry) or birth regions (regional philopatry) for either parturition or mating, even though they make long-distance movements that would allow them to breed elsewhere. More than 80 peer-reviewed articles, constituting the majority of published shark tracking and population genetic studies, provide evidence of at least one of these behaviors in a combined 31 shark species from six of the eight extant orders. Residency, site fidelity, and philopatry can alone or in combination structure many coastal shark populations on finer geographic scales than expected based on their potential for dispersal. This information should therefore be used to scale and inform assessment, management, and conservation activities intended to restore depleted shark populations. Expected final online publication date for the Annual Review of Marine Science Volume 7 is January 03, 2015. Please see http://www.annualreviews.org/catalog/pubdates.aspx for revised estimates.
Coastal watersheds support more than one half of the world’s human population and are experiencing unprecedented urban, agricultural, and industrial expansion. The freshwater–marine continua draining these watersheds are impacted increasingly by nutrient inputs and resultant eutrophication, including symptomatic harmful algal blooms, hypoxia, finfish and shellfish kills, and loss of higher plant and animal habitat. In addressing nutrient input reductions to stem and reverse eutrophication, phosphorus (P) has received priority traditionally in upstream freshwater regions, while controlling nitrogen (N) inputs has been the focus of management strategies in estuarine and coastal waters. However, freshwater, brackish, and full-salinity components of this continuum are connected structurally and functionally. Intensification of human activities has caused imbalances in N and P loading, altering nutrient limitation characteristics and complicating successful eutrophication control along the continuum. Several recent examples indicate the need for dual N and P input constraints as the only nutrient management option effective for long-term eutrophication control. Climatic changes increase variability in freshwater discharge with more severe storms and intense droughts and interact closely with nutrient inputs to modulate the magnitude and relative proportions of N and P loading. The effects of these interactions on phytoplankton production and composition were examined in two neighboring North Carolina lagoonal estuaries, the New River and Neuse River Estuaries, which are experiencing concurrent eutrophication and climatically driven hydrologic variability. Efforts aimed at stemming estuarine and coastal eutrophication in these and other similarly impacted estuarine systems should focus on establishing N and P input thresholds that take into account effects of hydrologic variability, so that eutrophication and harmful algal blooms can be controlled over a range of current and predicted climate change scenarios.
Land-use change, such as agricultural expansion and urbanization, can affect riverine biological diversity and ecosystem functioning. Identifying the major stressors associated with catchment land-use change is a prerequisite for devising successful river conservation and restoration strategies. Here, we analyzed land-use effects on the fatty acid (FA) composition and concentrations in suspended particulate organic matter (SPOM) along a fourth-order tropical river, the Rio das Mortes. Thereby, we aimed at testing the potential of fatty acids in riverine suspended particulate organic matter (SPOM-FAs) as indicators of land-use change in tropical catchments, and at identifying major human impacts on the biochemical composition of SPOM, which represents an important basal energy and organic matter resource for aquatic consumers. River water SPOM and total FA concentrations ranged between 2.8 and 10.2 mg dry weight (DW) L− 1 and between 130.6 and 268.2 μg DW L− 1, respectively, in our study. Urbanization was the only land-use category correlating with both FA composition and concentrations, despite its low contribution to whole catchment (1.5–5.6%) and riparian buffer land cover (1.7–6.6%). Higher concentrations of saturated FAs, especially C16:0 and C18:0, which are the main components of domestic sewage, were observed at sampling stations downstream of urban centers, and were highly correlated to urbanization, especially within the 60 m riparian buffer zone. Compared to water chemical characteristics (inorganic nutrients, dissolved oxygen, pH, and specific conductance) and river habitat structural integrity, FA variables exhibited a higher variability along the investigated river and were more strongly correlated to urban land use, suggesting that SPOM-FA profiles may be an efficient indicator of urban land-use impacts on larger tropical rivers. High total FA concentrations in the SPOM of urbanized tropical rivers may represent high-energy biochemical subsidies to food webs, potentially leading to changes in functional ecosystem characteristics, such as bacterial and suspension-feeder production.
In many fisheries, some component of the catch is usually released. Quantifying the
effects of capture and release on fish survival is critical for determining which practices are sustainable,
particularly for threatened species. Using a standardized fishing technique, we studied
sublethal (blood physiology and reflex impairment assessment) and lethal (post-release mortality
with satellite tags) outcomes of fishing stress on 5 species of coastal sharks (great hammerhead,
bull, blacktip, lemon, and tiger). Species-specific differences were detected in whole blood
lactate, partial pressure of carbon dioxide, and pH values, with lactate emerging as the sole
parameter to be significantly affected by increasing hooking duration and shark size. Species-specific
differences in reflex impairment were also found; however, we did not detect any significant
relationships between reflex impairment and hooking duration. Taken together, we ranked each
species according to degree of stress response, from most to least disturbed, as follows: hammerhead
shark > blacktip shark > bull shark > lemon shark > tiger shark. Satellite tagging data
revealed that nearly 100% of all tracked tiger sharks reported for at least 4 wk after release, which
was significantly higher than bull (74.1%) and great hammerhead (53.6%) sharks. We discuss
which mechanisms may lead to species-specific differences in sensitivity to fishing and suggest
that observed variation in responses may be influenced by ecological and evolutionary phenomena.
Moreover, our results show that certain species (i.e. hammerhead sharks in this study) are
inherently vulnerable to capture stress and mortality resulting from fisheries interactions and
should receive additional attention in future conservation strategies.
In the course of monthly sampling in 2008–2010, two regions of the littoral of the Yenisei river were compared. One of these regions (conventionally pure) was situated upstream of Krasnoyarsk, while the other (conventionally polluted) was downstream of Krasnoyarsk. The concentrations of heavy metals, oil products, phenols, biogenic elements and essential polyunsaturated fatty acids (PUFAs) in various components of the river ecosystem were determined. It was discovered that the anthropogenic pollution causes a decrease in the resources of essential PUFA in the biomass of the upper links of the food chain of the river ecosystem.
Lipid and fatty acid composition of broodstock diet have been identified as major dietary factors that determine successful reproduction and survival of offspring. Some fish species readily incorporate dietary unsaturated fatty acids into eggs, even during the course of the spawning season. Highly unsaturated fatty acids (HUFA) with 20 or more carbon atoms affect, directly or through their metabolites, fish maturation and steroidogenesis. In some species, HUFA in broodstock diets increases fecundity, fertilization and egg quality. As in higher vertebrates, vitamin E deficiency affects reproductive performance, causing immature gonads and lower hatching rate and survival of offspring. For example, elevation of dietary α-tocopherol levels has been found to reduce the percentage of abnormal eggs and increase fecundity in the gilthead seabream (Sparus aurata). Ascorbic acid has also been shown to play an important role in salmonid reproduction, where the dietary requirement of broodstock was higher than that of juveniles. Among different feed ingredients, cuttlefish, squid and krill meals are recognized as valuable components of broodstock diets. The protein component of cuttlefish and squid together with their optimal concentration of HUFA appear to be responsible for their positive effect on reproductive performance. Both polar and nonpolar lipid fractions of raw krill were found to effectively improve egg quality. © 2001 Published by Elsevier Science B.V.