1
|
Chiu CC, Yao CT, Liao BY, Li SH. Convergent evolution of kidney sizes and supraorbital salt glands for birds living in saline habitats. iScience 2024; 27:109169. [PMID: 38433889 PMCID: PMC10904986 DOI: 10.1016/j.isci.2024.109169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Revised: 10/30/2023] [Accepted: 02/06/2024] [Indexed: 03/05/2024] Open
Abstract
Only a small number of avian species inhabit salty environments. To understand how they adapted, we examined the evolution of kidney sizes, supraorbital salt glands (SSGs), and the utilization of salty habitats across 230 species spanning 25 avian orders. Phylogenetic analysis indicates that SSGs, large kidneys, and thriving in salty habitats emerged convergently in birds. Transition rate analysis reveals that species possessing SSGs and large kidneys tended to move from low-to high-salinity environments, while others moved in the opposite direction. However, habitat salinity also influenced kidney evolution; lineages residing in high-salinity environments tended to develop larger kidneys than those in low-salinity environments. Our findings suggest that SSGs and large kidneys may have evolved through adaptation to high salinity. Overall, habitat conditions and physiological traits influenced avian adaptation to salty environments in a reciprocal manner. These results shed the new light on the evolutionary mechanisms underlying functional diversity in birds.
Collapse
Affiliation(s)
- Chi-Cheng Chiu
- School of Life Science, National Taiwan Normal University, Taipei 11677, Taiwan
| | - Cheng-Te Yao
- High altitude research station, Taiwan Endemic Species Research Institute, Nantou 55244, Taiwan
| | - Ben-Yang Liao
- Institute of Population Health Sciences, National Health Research Institutes, Zhunan 350, Taiwan
| | - Shou-Hsien Li
- School of Life Science, National Taiwan Normal University, Taipei 11677, Taiwan
| |
Collapse
|
2
|
Oortwijn T, de Fouw J, Petersen JM, van Gils JA. Sulfur in lucinid bivalves inhibits intake rates of a molluscivore shorebird. Oecologia 2022; 199:69-78. [PMID: 35486255 DOI: 10.1007/s00442-022-05170-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Accepted: 03/28/2022] [Indexed: 11/25/2022]
Abstract
A forager's energy intake rate is usually constrained by a combination of handling time, encounter rate and digestion rate. On top of that, food intake may be constrained when a forager can only process a maximum amount of certain toxic compounds. The latter constraint is well described for herbivores with a limited tolerance to plant secondary metabolites. In sulfidic marine ecosystems, many animals host chemoautotrophic endosymbionts, which store sulfur compounds as an energy resource, potentially making their hosts toxic to predators. The red knot Calidris canutus canutus is a molluscivore shorebird that winters on the mudflats of Banc d'Arguin, where the most abundant bivalve prey Loripes orbiculatus hosts sulfide-oxidizing bacteria. In this system, we studied the potential effect of sulfur on the red knots' intake rates, by offering Loripes with various sulfur content to captive birds. To manipulate toxicity, we starved Loripes for 10 days by removing them from their symbiont's energy source sulfide. As predicted, we found lower sulfur concentrations in starved Loripes. We also included natural variation in sulfur concentrations by offering Loripes collected at two different locations. In both cases lower sulfur levels in Loripes resulted in higher consumption rates in red knots. Over time the red knots increased their intake rates on Loripes, showing their ability to adjust to a higher intake of sulfur.
Collapse
Affiliation(s)
- Tim Oortwijn
- Department Coastal Systems (COS), NIOZ Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB, Den Burg (Texel), The Netherlands.
| | - Jimmy de Fouw
- Department Coastal Systems (COS), NIOZ Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB, Den Burg (Texel), The Netherlands
- Faculty of Science, Department of Aquatic Ecology and Environmental Biology, Institute for Water and Wetland Research, Radboud University Nijmegen, Heyendaalseweg 135, 6525 AJ, Nijmegen, The Netherlands
| | - Jillian M Petersen
- Centre for Microbiology and Environmental Systems Science, University of Vienna, Djerassiplatz 1, 1030, Vienna, Austria
| | - Jan A van Gils
- Department Coastal Systems (COS), NIOZ Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790 AB, Den Burg (Texel), The Netherlands
- Conservation Ecology Group, Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, PO Box 11103, 9700 CC, Groningen, The Netherlands
| |
Collapse
|
3
|
Age-dependent shifts and spatial variation in the diet of endangered Black-faced Spoonbill (Platalea minor) chicks. PLoS One 2021; 16:e0253469. [PMID: 34242251 PMCID: PMC8270140 DOI: 10.1371/journal.pone.0253469] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Accepted: 06/05/2021] [Indexed: 11/30/2022] Open
Abstract
The endangered Black-faced Spoonbill (Platalea minor) strictly breeds in marine environments and is threatened by the rapid loss of coastal wetlands within its breeding range. Adults with chicks are thought to gradually switch feeding sites from freshwater wetlands to coastal mudflats as the chicks’ osmoregulatory system develops. We investigated age-dependent shifts in the diet of Black-faced Spoonbill chicks at four breeding colonies with varying freshwater habitat availability by examining stable isotopes (δ13C, δ15N) between the tip (grown at the age of 10 days) and middle (grown at the age of 22 days) portions of their primary feathers. The δ13C value of the middle portions was significantly higher than that of the tips, which suggested that the ratio of marine resources increased with the growth and development of chicks. A Bayesian isotope mixing model revealed that the diet proportion of marine prey in the early-chick rearing season was slightly higher than in the late-chick rearing season at three colonies in inshore areas, although this proportion was approximately 60% even in the early chick-rearing period. In contrast, isotopic values and reconstructed diet composition suggested that chicks in an offshore colony with limited freshwater wetlands relied more heavily on freshwater diets for both chick-rearing periods (>80%). Our results suggest that the shifts in feeding sites seen in previous studies might be related to the age-dependent dietary shift of chicks, highlighting the importance of freshwater wetlands for spoonbills on offshore islands without an inflow of freshwater in nearby intertidal mudflats. These findings emphasize the importance of freshwater prey and wetlands even for the endangered marine-breeding spoonbills, even though the negative impact of salt stress remains inconclusive.
Collapse
|
4
|
Brischoux F, Lillywhite HB, Shine R, Pinaud D. Osmoregulatory ability predicts geographical range size in marine amniotes. Proc Biol Sci 2021; 288:20203191. [PMID: 33823670 PMCID: PMC8059505 DOI: 10.1098/rspb.2020.3191] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2020] [Accepted: 02/04/2021] [Indexed: 12/21/2022] Open
Abstract
Species that are distributed over wide geographical ranges are likely to encounter a greater diversity of environmental conditions than do narrowly distributed taxa, and thus we expect a correlation between size of geographical range and breadth of physiological tolerances to abiotic challenges. That correlation could arise either because higher physiological capacity enables range expansion, or because widely distributed taxa experience more intense (but spatially variable) selection on physiological tolerances. The invasion of oceanic habitats by amniotic vertebrates provides an ideal system with which to test the predicted correlation between range size and physiological tolerances, because all three lineages that have secondarily moved into marine habitats (mammals, birds, reptiles) exhibit morphological and physiological adaptations to excrete excess salt. Our analyses of data on 62 species (19 mammals, 18 birds, 24 reptiles) confirm that more-widely distributed taxa encounter habitats with a wider range of salinities, and that they have higher osmoregulatory ability as determined by sodium concentrations in fluids expelled from salt-excreting organs. This result remains highly significant even in models that incorporate additional explanatory variables such as metabolic mode, body size and dietary habits. Physiological data thus may help to predict potential range size and perhaps a species' vulnerability to anthropogenic disturbance.
Collapse
Affiliation(s)
- François Brischoux
- Centre d'Etudes Biologiques de Chizé, CEBC UMR 7372 CNRS-La Rochelle Université, 79360 Villiers en Bois, France
| | | | - Richard Shine
- Department of Biological Sciences, Macquarie University, New South Wales 2109, Australia
| | - David Pinaud
- Centre d'Etudes Biologiques de Chizé, CEBC UMR 7372 CNRS-La Rochelle Université, 79360 Villiers en Bois, France
| |
Collapse
|
5
|
Sabat P, Bozinovic F, Contreras-Ramos C, Nespolo RF, Newsome SD, Quirici V, Maldonado K, Peña-Villalobos I, Ramirez-Otarola N, Sanchez-Hernandez JC. The interplay between ambient temperature and salt intake affects oxidative status and immune responses in a ubiquitous Neotropical passerine, the rufous-collared sparrow. Comp Biochem Physiol A Mol Integr Physiol 2019; 234:50-59. [DOI: 10.1016/j.cbpa.2019.04.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2019] [Revised: 03/30/2019] [Accepted: 04/18/2019] [Indexed: 12/28/2022]
|
6
|
Mapping wader biodiversity along the East Asian-Australasian flyway. PLoS One 2019; 14:e0210552. [PMID: 30682055 PMCID: PMC6347144 DOI: 10.1371/journal.pone.0210552] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 12/27/2018] [Indexed: 11/19/2022] Open
Abstract
Background and goal The study is conducted to facilitate conservation of migratory wader species along the East Asian-Australasian Flyway, particularly to 1) Identify hotspots of wader species richness along the flyway and effectively map how these might change between breeding, non-breeding and migratory phases; 2) Determine if the existing network of protected areas (PA) is sufficient to effectively conserve wader biodiversity hotspots along the EAAF; 3) Assess how species distribution models can provide complementary distribution estimates to existing BirdLife range maps. Methods We use a species distribution modelling (SDM) approach (MaxEnt) to develop temporally explicit individual range maps of 57 migratory wader species across their annual cycle, including breeding, non-breeding and migratory phases, which in turn provide the first biodiversity hotspot map of migratory waders along the EAAF for each of these phases. We assess the protected area coverage during each migration period, and analyse the dominant environmental drivers of distributions for each period. Additionally, we compare model hotspots to those existing range maps of the same species obtained from the BirdLife Internationals’ database. Results Our model results indicate an overall higher and a spatially different species richness pattern compared to that derived from a wader biodiversity hotspot map based on BirdLife range maps. Field observation records from the eBird database for our 57 study species confirm many of the hotspots revealed by model outputs (especially within the Yellow Sea coastal region), suggesting that current richness of the EAAF may have been underestimated and certain hotspots overlooked. Less than 10% of the terrestrial zones area (inland and coastal) which support waders are protected and, only 5% of areas with the highest 10% species richness is protected. Main conclusions The study results suggest the need for new areas for migratory wader research and conservation priorities including Yellow Sea region and Russian far-East. It also suggests a need to increase the coverage and percentage of current PA network to achieve Aichi Target 11 for Flyway countries, including giving stronger consideration to the temporal dynamics of wader migration.
Collapse
|
7
|
The earliest evidence for a supraorbital salt gland in dinosaurs in new Early Cretaceous ornithurines. Sci Rep 2018; 8:3969. [PMID: 29507398 PMCID: PMC5838252 DOI: 10.1038/s41598-018-22412-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Accepted: 02/15/2018] [Indexed: 11/08/2022] Open
Abstract
Supraorbital fossae occur when salt glands are well developed, a condition most pronounced in marine and desert-dwelling taxa in which salt regulation is key. Here, we report the first specimens from lacustrine environments of the Jehol Biota that preserve a distinct fossa above the orbit, where the salt gland fossa is positioned in living birds. The Early Cretaceous ornithurine bird specimens reported here are about 40 million years older than previously reported Late Cretaceous marine birds and represent the earliest described occurrence of the fossa. We find no evidence of avian salt gland fossae in phylogenetically earlier stem birds or non-avialan dinosaurs, even in those argued to be predominantly marine or desert dwelling. The apparent absence of this feature in more basal dinosaurs may indicate that it is only after miniaturization close to the origin of flight that excretory mechanisms were favored over exclusively renal mechanisms of salt regulation resulting in an increase in gland size leaving a bony trace. The ecology of ornithurine birds is more diverse than in other stem birds and may have included seasonal shifts in foraging range, or, the environments of some of the Jehol lakes may have included more pronounced periods of high salinity.
Collapse
|
8
|
Ramírez F, Rodríguez C, Seoane J, Figuerola J, Bustamante J. How will climate change affect endangered Mediterranean waterbirds? PLoS One 2018; 13:e0192702. [PMID: 29438428 PMCID: PMC5811028 DOI: 10.1371/journal.pone.0192702] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2017] [Accepted: 01/29/2018] [Indexed: 11/18/2022] Open
Abstract
Global warming and direct anthropogenic impacts, such as water extraction, largely affect water budgets in Mediterranean wetlands, thereby increasing wetland salinities and isolation, and decreasing water depths and hydroperiods (duration of the inundation period). These wetland features are key elements structuring waterbird communities. However, the ultimate and net consequences of these dynamic conditions on waterbird assemblages are largely unknown. We combined regular sampling of waterbird presence through one annual cycle with in-situ data on relevant environmental predictors of waterbird distribution to model habitat selection for 69 species in a typical Mediterranean wetland network in southwestern Spain. Species associations with environmental features were subsequently used to predict changes in habitat suitability for each species under three climate change scenarios (encompassing changes in environmental predictors that ranged from 10% to 50% change as predicted by regional climatic models). Waterbirds distributed themselves unevenly throughout environmental gradients and water salinity was the most important gradient structuring the distribution of the community. Environmental suitability for the guilds of diving birds and vegetation gleaners will decline in future climate scenarios, while many small wading birds will benefit from changing conditions. Resident species and those that breed in this wetland network will also be more negatively impacted than those using this area for wintering or stopover. We provide a tool that can be used in a horizon-scanning framework to identify emerging issues in waterbird conservation and to anticipate suitable management actions.
Collapse
Affiliation(s)
- Francisco Ramírez
- Department of Wetland Ecology, Estación Biológica de Doñana (CSIC), C/ Américo Vespucio 26, Sevilla, Spain
- Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals, Universitat de Barcelona, Facultat de Biologia, Avda. Diagonal 643, Barcelona, Spain
- * E-mail: ,
| | - Carlos Rodríguez
- Department of Conservation Biology, Estación Biológica de Doñana (CSIC), C/ Américo Vespucio 26, Sevilla, Spain
| | - Javier Seoane
- Terrestrial Ecology Group (TEG). Departamento de Ecología. Universidad Autónoma de Madrid, Madrid, Spain
| | - Jordi Figuerola
- Department of Wetland Ecology, Estación Biológica de Doñana (CSIC), C/ Américo Vespucio 26, Sevilla, Spain
| | - Javier Bustamante
- Department of Wetland Ecology, Estación Biológica de Doñana (CSIC), C/ Américo Vespucio 26, Sevilla, Spain
- Remote Sensing and GIS Lab (LAST-EBD). Estación Biológica de Doñana (CSIC), C/ Américo Vespucio 26, Sevilla, Spain
| |
Collapse
|
9
|
Rocha AR, Silva R, Villegas A, Sánchez-Guzmán JM, Ramos JA, Masero JA. Physiological, Morphological and Behavioural Responses of Self-Feeding Precocial Chicks Copying with Contrasting Levels of Water Salinity during Development. PLoS One 2016; 11:e0165364. [PMID: 27788200 PMCID: PMC5082863 DOI: 10.1371/journal.pone.0165364] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2016] [Accepted: 10/11/2016] [Indexed: 11/18/2022] Open
Abstract
Combined physiological and behavioural responses to salt loads during development have rarely been studied in air-breathing vertebrates able to inhabit hypersaline habitats, but they may be of particular importance in understanding, for example, the differences among species in patterns of habitat use or ontogenetic diet switches. Here, we compared the physiological and behavioural responses of self-feeding precocial chicks developed in contrasting levels of water salinity. The model species was the Black-winged Stilt (Himantopus himantopus) a precocial shorebird that breeds in a range of habitats from freshwater to hypersaline wetlands. Specifically, we compared resting metabolic rate (RMR), heat shock proteins (Hsp70), plasma ions, hematocrit, body mass, body size, growth rate and head-shaking behaviour of captive-reared Black-winged Stilt fledglings developed under fresh (0 ‰), saline (20 ‰), and hypersaline (60 ‰) water. Contrary to expectations, none of the physiological and morphological variables measured differed significantly among treatments. Likewise, the RMR of wild and captive-reared fledglings was similar. Surprisingly, the saltgland mass of wild fledglings from freshwater and those from hypersaline habitats was also similar. However, head-shaking, a behavioural response associated to minimize salt intake and to expel the secretions of salt glands, differed according to salinity source: head-shaking rate increased with increasing salinity. The results of this study support the key role of behavioural osmoregulation in avoiding salt stress during development.
Collapse
Affiliation(s)
- Afonso R Rocha
- MARE-Marine and Environmental Sciences Centre, Department of Life Sciences, University of Coimbra, 3000-456, Coimbra, Portugal
| | - Rita Silva
- MARE-Marine and Environmental Sciences Centre, Department of Life Sciences, University of Coimbra, 3000-456, Coimbra, Portugal
| | - Auxiliadora Villegas
- Department de Anatomy, Cell Biology and Zoology, University of Extremadura, Avenida de Elvas s/n, 06071, Badajoz, Spain
| | - Juan M Sánchez-Guzmán
- Department de Anatomy, Cell Biology and Zoology, University of Extremadura, Avenida de Elvas s/n, 06071, Badajoz, Spain
| | - Jaime A Ramos
- MARE-Marine and Environmental Sciences Centre, Department of Life Sciences, University of Coimbra, 3000-456, Coimbra, Portugal
| | - José A Masero
- Department de Anatomy, Cell Biology and Zoology, University of Extremadura, Avenida de Elvas s/n, 06071, Badajoz, Spain
| |
Collapse
|
10
|
Peña-Villalobos I, Narváez C, Sabat P. Metabolic cost of osmoregulation in a hypertonic environment in the invasive African clawed frog Xenopus laevis. Biol Open 2016; 5:955-61. [PMID: 27334694 PMCID: PMC4958268 DOI: 10.1242/bio.016543] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 05/31/2016] [Indexed: 12/26/2022] Open
Abstract
Studies of aquatic invertebrates reveal that salinity affects feeding and growth rates, reproduction, survival, and diversity. Little is known, however, about how salinity impacts the energy budget of vertebrates and amphibians in particular. The few studies focused on this topic in vertebrates suggest that the ingestion of salts and the resulting osmoregulatory activity is energetically expensive. We analyzed the effect of saline acclimation on standard metabolic rates (SMR) and the activities of metabolic enzymes of internal organs and osmoregulatory variables (plasma osmolality and urea plasma level) in females of Xenopus laevis by means of acclimating individuals to an isosmotic (235 mOsm NaCl; ISO group) and hyper-osmotic (340 mOsm NaCl; HYP group) environment for 40 days. After acclimation, we found that total and mass-specific SMR was approximately 80% higher in the HYP group than those found in the ISO group. These changes were accompanied by higher citrate synthase activities in liver and heart in the HYP group than in the ISO group. Furthermore, we found a significant and positive correlation between metabolic rates and plasma urea, and citrate synthase activity in liver and heart. These results support the notion that the cost of osmoregulation is probably common in most animal species and suggest the existence of a functional association between metabolic rates and the adjustments in osmoregulatory physiology, such as blood distribution and urea synthesis.
Collapse
Affiliation(s)
- Isaac Peña-Villalobos
- Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago 7800003, Chile
| | - Cristóbal Narváez
- Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago 7800003, Chile
| | - Pablo Sabat
- Departamento de Ciencias Ecológicas, Facultad de Ciencias, Universidad de Chile, Santiago 7800003, Chile Center of Applied Ecology and Sustainability (CAPES), Pontificia Universidad Católica de Chile, Santiago 6513677, Chile
| |
Collapse
|
11
|
Gutiérrez JS, Piersma T. Ecological context determines the choice between prey of different salinities. Behav Ecol 2016. [DOI: 10.1093/beheco/arv185] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
|
12
|
How salinity and temperature combine to affect physiological state and performance in red knots with contrasting non-breeding environments. Oecologia 2015; 178:1077-91. [DOI: 10.1007/s00442-015-3308-4] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2014] [Accepted: 03/25/2015] [Indexed: 10/23/2022]
|
13
|
Navedo JG, Hahn S, Parejo M, Abad-Gómez JM, Gutiérrez JS, Villegas A, Sánchez-Guzmán JM, Masero JA. Unravelling trophic subsidies of agroecosystems for biodiversity conservation: food consumption and nutrient recycling by waterbirds in Mediterranean rice fields. THE SCIENCE OF THE TOTAL ENVIRONMENT 2015; 511:288-297. [PMID: 25553543 DOI: 10.1016/j.scitotenv.2014.12.068] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2014] [Revised: 12/19/2014] [Accepted: 12/21/2014] [Indexed: 06/04/2023]
Abstract
Waterbirds can reallocate a considerable amount of nutrients within agricultural fields and between agriculture sites and wetlands. However their effects on biogeochemical cycles have rarely been quantified. We estimated bird numbers, diet (from stable isotope analysis), food supply, and the food consumption on rice fields by overwintering waterbirds in one of the most important areas for rice production in southwestern Europe and a key area for various migrating and resident waterbird species. Herein, we modelled the nutrient (N and P) recycling in rice fields, and their transport to reservoirs. The energy consumption by waterbirds (96,605±18,311 individuals) on rice fields during winter averaged at 89.9±39.0 kJ·m(-2), with its majority (89.9%) belonging to foraging on rice seeds. Thus, the birds removed about 26% of rice seeds leftover after harvest (estimated in 932.5±504.7 seeds·m(-2) in early winter) wherein common cranes and dabbling ducks (four species) were the most important consumers. Waterbirds foraging and roosting in the rice fields recycled more than 24.1 (1.0 kg·ha(-1)) of N and an additional 5.0 tons (0.2 kg·ha(-1)) of P in the Extremadura's rice fields during winter. Additionally, we estimated that 2.3 tons of N and 550 kg of P were removed from rice fields and transported to reservoirs. The seasonal foraging of wildlife should result in a direct benefit for rice farmers by improving nutrient recycling through defecation by waterbirds with respect to artificial fertilisation. Additionally, rice fields located in the cranes' core wintering areas can provide sufficient food supply to induce habitat shift from their traditional wintering habitat in 'dehesas' to rice fields, which causes indirect socioeconomic benefit through reduced acorn consumption by cranes. Our modelling approach may thus be especially helpful for management decisions regarding rice agroecosystems in areas which are also important for the conservation of migratory waterbirds.
Collapse
Affiliation(s)
- Juan G Navedo
- Instituto de Ciencias Marinas y Limnológicas, Universidad Austral de Chile, Facultad de Ciencias, Campus Isla Teja, 5090000 Valdivia, Chile; Conservation Biology Research Group, Universidad de Extremadura, Avda. Elvas s/n, 06002 Badajoz, Spain.
| | - Steffen Hahn
- Department Bird Migration, Swiss Ornithological Institute, Seerose 1, 6204 Sempach, Switzerland
| | - Manuel Parejo
- Conservation Biology Research Group, Universidad de Extremadura, Avda. Elvas s/n, 06002 Badajoz, Spain
| | - José M Abad-Gómez
- Conservation Biology Research Group, Universidad de Extremadura, Avda. Elvas s/n, 06002 Badajoz, Spain
| | - Jorge S Gutiérrez
- Conservation Biology Research Group, Universidad de Extremadura, Avda. Elvas s/n, 06002 Badajoz, Spain; Department of Marine Ecology, Royal Netherlands Institute for Sea Research (NIOZ), PO Box 59, 1790 AB Den Burg, Texel, The Netherlands
| | - Auxiliadora Villegas
- Conservation Biology Research Group, Universidad de Extremadura, Avda. Elvas s/n, 06002 Badajoz, Spain
| | - Juan M Sánchez-Guzmán
- Conservation Biology Research Group, Universidad de Extremadura, Avda. Elvas s/n, 06002 Badajoz, Spain
| | - José A Masero
- Conservation Biology Research Group, Universidad de Extremadura, Avda. Elvas s/n, 06002 Badajoz, Spain
| |
Collapse
|
14
|
Osmoregulatory and metabolic costs of salt excretion in the Rufous-collared sparrow Zonotrichia capensis. Comp Biochem Physiol A Mol Integr Physiol 2013; 164:314-8. [DOI: 10.1016/j.cbpa.2012.10.027] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2012] [Revised: 10/20/2012] [Accepted: 10/20/2012] [Indexed: 11/17/2022]
|
15
|
Gutiérrez JS, Abad-Gómez JM, Villegas A, Sánchez-Guzmán JM, Masero JA. Effects of salinity on the immune response of an 'osmotic generalist' bird. Oecologia 2012; 171:61-9. [PMID: 22782496 DOI: 10.1007/s00442-012-2405-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2011] [Accepted: 06/19/2012] [Indexed: 10/28/2022]
Abstract
Salt stress can suppress the immune function of fish and other aquatic animals, but such an effect has not yet been examined in air-breathing vertebrates that frequently cope with waters (and prey) of contrasting salinities. We investigated the effects of seawater salinity on the strength and cost of mounting an immune response in the dunlin Calidris alpina, a long-distance migratory shorebird that shifts seasonally from freshwater environments during the breeding season to marine environments during migration and the winter period. Phytohaemagglutinin (PHA)-induced skin swelling, basal metabolic rate (BMR), body mass, fat stores, and plasma ions were measured in dunlins acclimated to either freshwater or seawater (salinity: 0.3 and 35.0 ‰, respectively). Seawater-acclimated dunlins mounted a PHA-induced swelling response that was up to 56 % weaker than those held under freshwater conditions, despite ad libitum access to food. Freshwater-acclimated dunlins significantly increased their relative BMR 48 h after PHA injection, whereas seawater-acclimated dunlins did not. However, this differential immune and metabolic response between freshwater- and seawater-acclimated dunlins was not associated with significant changes in body mass, fat stores or plasma ions. Our results indicate that the strength of the immune response of this small-sized migratory shorebird was negatively influenced by the salinity of marine habitats. Further, these findings suggest that the reduced immune response observed under saline conditions might not be caused by an energy or nutrient limitation, and raise questions about the role of osmoregulatory hormones in the modulation of the immune system.
Collapse
Affiliation(s)
- Jorge S Gutiérrez
- Department of Anatomy, Cell Biology and Zoology, Faculty of Sciences, University of Extremadura, Badajoz, Spain.
| | | | | | | | | |
Collapse
|