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Dreyer S, Marcu D, Keyser S, Bennett M, Maree L, Koeppel K, Abernethy D, Petrik L. Factors in the decline of the African penguin: Are contaminants of emerging concern (CECs) a potential new age stressor? MARINE POLLUTION BULLETIN 2024; 206:116688. [PMID: 39029148 DOI: 10.1016/j.marpolbul.2024.116688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2024] [Revised: 07/01/2024] [Accepted: 07/03/2024] [Indexed: 07/21/2024]
Abstract
The African penguin is currently experiencing a significant decline, with just over 10,000 breeding pairs left. A substantial body of research reflects the impacts of contaminants of emerging concern (CECs) on the marine environment, with wastewater treatment plants reported as one of the main sources of CEC release. In South Africa, CECs were identified contaminating the marine environment and bioaccumulating in several marine species. Approximately 70 % of all African penguin colonies breed in close proximity to cities and/or harbors in South Africa. Currently, the impact of CECs as a stressor upon the viability of African penguin populations is unknown. Based on the search results there was a clear lack of information on CECs' bioaccumulation and impact on the African penguin. This narrative review will thus focus on the prevalent sources and types of CECs and examine the reported consequences of constant exposure in seabirds, particularly African penguins.
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Affiliation(s)
- Stephanie Dreyer
- Animal Production Studies, Faculty of Veterinary Sciences, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa.
| | - Daniel Marcu
- School of Biological Sciences, University of East Anglia, NR4 7TJ, United Kingdom
| | - Shannen Keyser
- Comparative Spermatology Laboratory, Department of Medical Bioscience, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa
| | - Monique Bennett
- Comparative Spermatology Laboratory, Department of Medical Bioscience, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa
| | - Liana Maree
- Comparative Spermatology Laboratory, Department of Medical Bioscience, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa
| | - Katja Koeppel
- Animal Production Studies, Faculty of Veterinary Sciences, University of Pretoria, Private Bag X04, Onderstepoort 0110, South Africa
| | - Darrell Abernethy
- Aberystwyth School of Veterinary Science, Aberystwyth University, Ceredigion SY23 3FL, United Kingdom
| | - Leslie Petrik
- Environmental and Nano Sciences Group, Department of Chemistry, University of the Western Cape, Private Bag X17, Bellville 7535, South Africa
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2
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Leighton GRM, Froneman PW, Serieys LEK, Bishop JM. Sustained use of marine subsidies promotes niche expansion in a wild felid. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 914:169912. [PMID: 38184259 DOI: 10.1016/j.scitotenv.2024.169912] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Revised: 12/18/2023] [Accepted: 01/02/2024] [Indexed: 01/08/2024]
Abstract
The use of marine subsidies by terrestrial predators can facilitate substantial transfer of nutrients between marine and terrestrial ecosystems. Marine resource subsidies may have profound effects on predator ecology, influencing population and niche dynamics. Expanding niches of top consumers can impact ecosystem resilience and interspecific interactions, affecting predator-prey dynamics and competition. We investigate the occurrence, importance, and impact of marine resources on trophic ecology and niche dynamics in a highly generalist predator, the caracal (Caracal caracal), on the Cape Peninsula, South Africa. Caracals have flexible diets, feeding across a wide range of terrestrial and aquatic prey. We use carbon and nitrogen stable isotope analysis of fur samples (n = 75) to understand trophic position and niche shifts in coastal and inland foragers, as well as the implications of a diet rich in marine resources. We found significant differences in isotope signatures between these groups, with higher δ13C (P < 0.05) and δ15N values (P < 0.01) in coastal foragers. Isotope mixing models reveal that these elevated signatures were due to non-terrestrial food subsidies, where approximately a third of coastal foraging caracal diet comprised marine prey. The addition of marine prey species to diet increased both the trophic level and isotope niche size of coastal foraging caracals, with potential impacts on prey populations and competition. Our results suggest that marine prey are an important dietary resource for coastal foraging caracals, where seabirds, including two endangered species, are a major component of their diet. However, there are likely risks associated with these resource benefits, as routine consumption of seabirds is linked with higher pollutant burdens, particularly metals. Increased encounters between this terrestrial predator and seabirds may be a result of increased mainland colonies due to changes in habitat availability and the highly opportunistic and generalist foraging behaviour of a native predator.
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Affiliation(s)
- Gabriella R M Leighton
- Department of Zoology and Entomology, Rhodes University, PO Box 94, Grahamstown 6140, South Africa; Institute for Communities and Wildlife in Africa, Department of Biological Sciences, University of Cape Town, Rondebosch, Cape Town 7701, South Africa.
| | - P William Froneman
- Department of Zoology and Entomology, Rhodes University, PO Box 94, Grahamstown 6140, South Africa
| | - Laurel E K Serieys
- Institute for Communities and Wildlife in Africa, Department of Biological Sciences, University of Cape Town, Rondebosch, Cape Town 7701, South Africa; Panthera, NY, New York, USA; Cape Leopard Trust, Cape Town, South Africa
| | - Jacqueline M Bishop
- Institute for Communities and Wildlife in Africa, Department of Biological Sciences, University of Cape Town, Rondebosch, Cape Town 7701, South Africa
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Borecki P, Rosenberger J, Mucha A, Partyka A. Breeding behavior analysis in a large captive colony of African penguins (Spheniscus demersus) and its implications for population management and conservation. Sci Rep 2024; 14:3589. [PMID: 38351247 PMCID: PMC10864276 DOI: 10.1038/s41598-024-54105-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2023] [Accepted: 02/08/2024] [Indexed: 02/16/2024] Open
Abstract
The African penguin Spheniscus demersus, frequently housed in zoos, holds potential for future reintroduction efforts due to its declining wild population. This paper aims to explore various aspects of reproductive performance in African penguins within a large ex situ colony at Zoo Wrocław in Poland, covering 9 years of breeding behaviors. The analysis reveals parallels in colony growth and partner change patterns with those observed in the wild. Positive correlations were found between breeding success and pair-bond duration, with the increasing colony size influencing reproductive performance. Contrary to their wild counterparts, captive African penguins initiate breeding attempt and produce a fertilized egg at a younger age. However, successful breeding still requires gaining experience or forming pairs with more experienced partners. Our research indicates that providing captive African penguins with unlimited food resources and sufficient nesting space results in rapid colony growth. The increased colony size facilitates breeding behaviors that positively influence population dynamics, particularly through the maintenance of long-term pair bond relationships and the potential for partner changes when necessary or desirable to enhance breeding success. We present compelling case studies in pair fidelity, offering valuable insights and implications for the management of captive populations and conservation efforts.
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Affiliation(s)
- Paweł Borecki
- Department of Reproduction and Clinic of Farm Animals, Wroclaw University of Environmental and Life Sciences, Pl. Grunwaldzki 49, 50-366, Wrocław, Poland
- Zoo Wrocław, Ul. Wróblewskiego 1-5, 51-618, Wrocław, Poland
| | - Joanna Rosenberger
- Division of Poultry Breeding, Institute of Animal Breeding, Wroclaw University of Environmental and Life Sciences, Ul. Chełmońskiego 38C, 51-630, Wrocław, Poland
| | - Anna Mucha
- Department of Genetics, Wrocław University of Environmental and Life Sciences, Ul. Kożuchowska 7, 51-631, Wrocław, Poland
| | - Agnieszka Partyka
- Department of Reproduction and Clinic of Farm Animals, Wroclaw University of Environmental and Life Sciences, Pl. Grunwaldzki 49, 50-366, Wrocław, Poland.
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Froehlich F, Forbes N, Carrasco DC, Ludynia K, Parsons NJ, Worsfold RD, Dutton T. The Effects of Critical Care Nutrition on Weight Gain in African Penguin ( Spheniscus demersus) Chicks. J Avian Med Surg 2023; 37:217-225. [PMID: 37962315 DOI: 10.1647/d-20-00101] [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] [Indexed: 11/15/2023]
Abstract
Nutritional support in malnourished animals is an essential aspect of wildlife rehabilitation; this support is especially relevant when providing lifesaving nutrition to endangered species such as the African penguin (Spheniscus demersus). This study investigated the short-term effects of a commercially available, semi-elemental, critical care diet compared with a hand-made fish formula. Twenty-one African penguin chicks were selected on admission to the Southern African Foundation for the Conservation of Costal Birds in Cape Town, South Africa, in November 2015. Initial assessment included body weight, a full clinical exam, white blood cell count, packed cell volume, and total plasma protein. Ten animals received the commercial critical care diet, whereas a control group of 11 animals were fed hand-made formula for the 2-week study period. All animals were weighed daily and blood sampling was repeated after 14 days. The median weight of both groups increased significantly over 14 days (critical care diet χ2 = 10.1, P = 0.002; control χ2 = 7.4, P = 0.006). The difference was not significant between the groups for start weight (χ2 = 0.1, P = 0.725) or end weight (χ2 = 0, P = 1.000) and was not significantly different in the change over time for either absolute numbers (χ2 = 1.7, P = 0.193) or percent gain (χ2 = 0.8, P = 0.36). The values for packed cell volume, total plasma protein, and white blood cell count increased in all animals after the 14-day study period was complete. On the basis of the results of this study, it was determined that the differing diets led to similar weight gain.
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Affiliation(s)
- Fiona Froehlich
- University of Veterinary Medicine Vienna, Avian and Reptile Service, Veterinaerplatz 1, 1210, Vienna, Austria,
| | - Neil Forbes
- Vulture Alliance, International Centre of Birds of Prey, Bousldon House, Newent GL18 1JJ, United Kingdom
| | | | - Katta Ludynia
- Southern African Foundation for the Conservation of Coastal Birds, Cape Town 7441, South Africa
- Department of Biological Sciences, University of Cape Town, Cape Town 7701, South Africa
| | - Nola J Parsons
- Southern African Foundation for the Conservation of Coastal Birds, Cape Town 7441, South Africa
| | | | - Tom Dutton
- Great Western Exotics, Unit 10-16 Berkshire House, County Park Business Park, Swindon SN12NR, United Kingdom
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Feist F, Terranova F, Petersen GS, Tourtigues E, Friard O, Gamba M, Ludynia K, Gridley T, Pichegru L, Mathevon N, Reby D, Favaro L. Effect of Environmental Variables on African Penguin Vocal Activity: Implications for Acoustic Censusing. BIOLOGY 2023; 12:1191. [PMID: 37759590 PMCID: PMC10525562 DOI: 10.3390/biology12091191] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2023] [Revised: 08/26/2023] [Accepted: 08/29/2023] [Indexed: 09/29/2023]
Abstract
Global biodiversity is in rapid decline, and many seabird species have disproportionally poorer conservation statuses than terrestrial birds. A good understanding of population dynamics is necessary for successful conservation efforts, making noninvasive, cost-effective monitoring tools essential. Here, we set out to investigate whether passive acoustic monitoring (PAM) could be used to estimate the number of animals within a set area of an African penguin (Spheniscus demersus) colony in South Africa. We were able to automate the detection of ecstatic display songs (EDSs) in our recordings, thus facilitating the handling of large datasets. This allowed us to show that calling rate increased with wind speed and humidity but decreased with temperature, and to highlight apparent abundance variations between nesting habitat types. We then showed that the number of EDSs in our recordings positively correlated with the number of callers counted during visual observations, indicating that the density could be estimated based on calling rate. Our observations suggest that increasing temperatures may adversely impact penguin calling behaviour, with potential negative consequences for population dynamics, suggesting the importance of effective conservation measures. Crucially, this study shows that PAM could be successfully used to monitor this endangered species' populations with minimal disturbance.
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Affiliation(s)
- Franziska Feist
- ENES Bioacoustics Research Team, University of Saint-Etienne, 42100 Saint-Etienne, France
| | - Francesca Terranova
- Department of Life Sciences and Systems Biology, University of Turin, 10124 Turin, Italy
| | - Gavin Sean Petersen
- Southern African Foundation for the Conservation of Coastal Birds (SANCCOB), Cape Town 7441, South Africa
| | - Emma Tourtigues
- ENES Bioacoustics Research Team, University of Saint-Etienne, 42100 Saint-Etienne, France
| | - Olivier Friard
- Department of Life Sciences and Systems Biology, University of Turin, 10124 Turin, Italy
| | - Marco Gamba
- Department of Life Sciences and Systems Biology, University of Turin, 10124 Turin, Italy
| | - Katrin Ludynia
- Southern African Foundation for the Conservation of Coastal Birds (SANCCOB), Cape Town 7441, South Africa
- Department of Biodiversity and Conservation Biology, University of the Western Cape, Robert Sobukwe Road, Bellville 7535, South Africa
| | - Tess Gridley
- Statistics in Ecology, Environment and Conservation, Department of Statistical Sciences, University of Cape Town, Rondebosch, Cape Town 7701, South Africa
| | - Lorien Pichegru
- Institute for Coastal and Marine Research, Nelson Mandela Metropolitan University, Port Elisabeth 6031, South Africa
| | - Nicolas Mathevon
- ENES Bioacoustics Research Team, University of Saint-Etienne, 42100 Saint-Etienne, France
- Institut Universitaire de France, Ministry of Higher Education, Research and Innovation, 1 rue Descartes, CEDEX 05, 75231 Paris, France
| | - David Reby
- ENES Bioacoustics Research Team, University of Saint-Etienne, 42100 Saint-Etienne, France
- Institut Universitaire de France, Ministry of Higher Education, Research and Innovation, 1 rue Descartes, CEDEX 05, 75231 Paris, France
| | - Livio Favaro
- Department of Life Sciences and Systems Biology, University of Turin, 10124 Turin, Italy
- CAPE Department, Stazione Zoologica Anton Dohrn, 80121 Naples, Italy
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Roberts LC, Molini U, Coetzee LM, Khaiseb S, Roux JP, Kemper J, Roberts DG, Ludynia K, Doherr M, Abernethy D, Franzo G. Is Penguin Circovirus Circulating Only in the Antarctic Circle? Lack of Viral Detection in Namibia. Animals (Basel) 2023; 13:ani13091449. [PMID: 37174486 PMCID: PMC10177519 DOI: 10.3390/ani13091449] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 04/19/2023] [Accepted: 04/21/2023] [Indexed: 05/15/2023] Open
Abstract
The known host range of circoviruses is continuously expanding because of more intensive diagnostic activities and advanced sequencing tools. Recently, a new circovirus (penguin circovirus (PenCV)) was identified in the guano and cloacal samples collected from Adélie penguins (Pygoscelis adeliae) and chinstrap penguins (Pygoscelis antarcticus) in Antarctica. Although the virus was detected in several asymptomatic subjects, a potential association with feather disease was speculated. To investigate the occurrence and implications of PenCV in other penguin species located outside of Antarctica, a broad survey was undertaken in African penguins (Spheniscus demersus) on two islands off the southern Namibian coast. For this purpose, specific molecular biology assays were developed and validated. None of the 151 blood samples tested positive for PenCV. Several reasons could explain the lack of PenCV positive samples. African penguins and Pygoscelis species are separated by approximately 6000 km, so there is almost no opportunity for transmission. Similarly, host susceptibility to PenCV might be penguin genus-specific. Overall, the present study found no evidence of PenCV in African penguin colonies in Namibia. Further dedicated studies are required to assess the relevance of PenCV among different penguin species.
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Affiliation(s)
- Laura C Roberts
- Department of Production Animal Studies, Faculty of Veterinary Science, University of Pretoria, Pretoria 0110, South Africa
- Centre for Veterinary Wildlife Research, Faculty of Veterinary Science, University of Pretoria, Pretoria 0110, South Africa
| | - Umberto Molini
- School of Veterinary Medicine, Faculty of Health Sciences and Veterinary Medicine, Neudamm Campus, University of Namibia, Private Bag, Windhoek 13301, Namibia
- Central Veterinary Laboratory (CVL), 24 Goethe Street, Private Bag, Windhoek 18137, Namibia
| | - Lauren M Coetzee
- Central Veterinary Laboratory (CVL), 24 Goethe Street, Private Bag, Windhoek 18137, Namibia
| | - Siegfried Khaiseb
- Central Veterinary Laboratory (CVL), 24 Goethe Street, Private Bag, Windhoek 18137, Namibia
| | - Jean-Paul Roux
- African Penguin Conservation Project, Lüderitz 23016, Namibia
| | - Jessica Kemper
- African Penguin Conservation Project, Lüderitz 23016, Namibia
| | - David G Roberts
- Southern African Foundation for the Conservation of Coastal Birds (SANCCOB), Cape Town 7441, South Africa
| | - Katrin Ludynia
- Southern African Foundation for the Conservation of Coastal Birds (SANCCOB), Cape Town 7441, South Africa
- Department of Biodiversity & Conservation Biology, University of the Western Cape, Bellville 7535, South Africa
| | - Marcus Doherr
- Institute for Veterinary Epidemiology and Biostatistics, Department of Veterinary Medicine, University of Freie, Königsweg 67, 14163 Berlin, Germany
| | - Darrell Abernethy
- Centre for Veterinary Wildlife Research, Faculty of Veterinary Science, University of Pretoria, Pretoria 0110, South Africa
- Aberystwyth School of Veterinary Science, Department of Life Sciences, Aberystwyth University, Aberystwyth SY23 3DA, UK
| | - Giovanni Franzo
- Department of Animal Medicine, Production and Health, University of Padova, Legnaro, 35020 Padova, Italy
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Vanstreels RET, Parsons NJ, Sherley RB, Stander N, Strauss V, Kemper J, Waller L, Barham BJ, Ludynia K. Factors determining the number of seabirds impacted by oil spills and the success of their rehabilitation: Lessons learned from Namibia and South Africa. MARINE POLLUTION BULLETIN 2023; 188:114708. [PMID: 36773585 DOI: 10.1016/j.marpolbul.2023.114708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 02/01/2023] [Accepted: 02/03/2023] [Indexed: 06/18/2023]
Abstract
The coastal waters of Namibia and South Africa have an extensive history of oil spills, with 71 recorded up to 2021. Thirty-nine spills reportedly affected 83,224 seabirds, with African penguins (Spheniscus demersus; 91.0 %) and Cape gannets (Morus capensis; 8.5 %) most affected. Spills affecting seabirds were caused by unknown sources (46 %), bulk/cargo carriers (43 %), tankers (38 %) and ship-to-ship transfers (14 %). The number of penguins oiled was predicted by the breeding population size within 25 to 75 km, but not the volume of oiled spilled, the month or the year. Rehabilitation records from penguins oiled in spills since 2001 reveal that the day of admission (relative to the start of the spill) was predictive of packed cell volume, body mass, and plasma total solids, with the latter two being predictive of rehabilitation success. Our results highlight the importance of rapid monitoring at colonies to locate oiled birds in the event of spills.
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Affiliation(s)
- Ralph E T Vanstreels
- Institute of Research and Rehabilitation of Marine Animals (IPRAM), Vila Velha, Brazil.
| | - Nola J Parsons
- Southern African Foundation for the Conservation of Coastal Birds (SANCCOB), Cape Town, South Africa
| | - Richard B Sherley
- Environment and Sustainability Institute, University of Exeter, Penryn, United Kingdom; FitzPatrick Institute of African Ornithology, DST-NRF Centre of Excellence, University of Cape Town, Cape Town, South Africa; African Penguin Conservation Project, Lüderitz, Namibia
| | - Nicky Stander
- Southern African Foundation for the Conservation of Coastal Birds (SANCCOB), Cape Town, South Africa
| | - Venessa Strauss
- Southern African Foundation for the Conservation of Coastal Birds (SANCCOB), Cape Town, South Africa
| | | | - Lauren Waller
- Southern African Foundation for the Conservation of Coastal Birds (SANCCOB), Cape Town, South Africa
| | | | - Katrin Ludynia
- Southern African Foundation for the Conservation of Coastal Birds (SANCCOB), Cape Town, South Africa; Department of Biological Sciences, University of Cape Town, Cape Town, South Africa
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Driscoll MV, Tuttle AD, Romano TA. Fecal glucocorticoid analysis as a health monitoring tool for endangered African penguins (Spheniscus demersus). Gen Comp Endocrinol 2023; 330:114147. [PMID: 36272448 DOI: 10.1016/j.ygcen.2022.114147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 10/12/2022] [Accepted: 10/14/2022] [Indexed: 11/17/2022]
Abstract
African penguins (Spheniscus demersus) are an endangered species, with approximately 70,000 mature adults remaining in the wild. Population loss is linked to a combination of environmental and anthropogenic stressors. The aim of the study was to validate a commercially available enzyme immunoassay (EIA) to assess adrenal activity and measure the response to stressors in the feces of African penguins. Fecal samples (n = 609) were collected from 12 African penguins housed at Mystic Aquarium throughout their natural lifecycle, including breeding and molt, where measurable changes in fecal glucocorticoid metabolite (FGM) levels are predicted to occur. Fecal samples collected post-veterinary exam were used for biological validation. Longitudinal analysis shows a significant difference (p = <0.0001) between the average FGM levels during baseline and breeding season, 33.97 ± 1.30 ng/g and 50.21 ± 3.18 ng/g, respectively. Females displayed significantly higher FGM levels than males during both baseline (p = 0.0386; females = 38.80 ± 2.19 ng/g; males = 29.34 ± 1.37 ng/g) and breeding periods (p = 0.0175; females = 57.53 ± 4.84 ng/g; males = 42.69 ± 3.95 ng/g). Average FGM levels decreased significantly over the three-week molting period, from 85.40 ± 20.35 ng/g at week one to 20.23 ± 5.30 ng/g at week three. A seasonal difference in FGM levels was observed in both male and female fecal samples, with Fall having the highest average FGM levels, 54.38 ± 3.64 ng/g, and Summer the lowest, 30.87 ± 2.21 ng/g. General linear mixed model analysis determined that lifecycle (females) and visitor presence (males) were the two factors which best explained the variation in FGM levels observed, however neither factor was found to be significant. These results show FGM analysis can detect physiologically meaningful changes in endocrine activity in African penguins and can be used to monitor health for penguins in aquaria and in the wild, thus contributing to conservation efforts for the survival of the species.
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Affiliation(s)
- Maureen V Driscoll
- Sea Research Foundation Inc., d/b/a Mystic Aquarium, 55 Coogan Boulevard, Mystic, CT 06355, USA; University of Connecticut, Department of Marine Sciences, 1084 Shennecossett Road, Groton, CT 06340, USA.
| | - Allison D Tuttle
- Sea Research Foundation Inc., d/b/a Mystic Aquarium, 55 Coogan Boulevard, Mystic, CT 06355, USA
| | - Tracy A Romano
- Sea Research Foundation Inc., d/b/a Mystic Aquarium, 55 Coogan Boulevard, Mystic, CT 06355, USA; University of Connecticut, Department of Marine Sciences, 1084 Shennecossett Road, Groton, CT 06340, USA
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9
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Difficulties in summing log-normal distributions for abundance and potential solutions. PLoS One 2023; 18:e0280351. [PMID: 36634090 PMCID: PMC9836268 DOI: 10.1371/journal.pone.0280351] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2022] [Accepted: 12/27/2022] [Indexed: 01/13/2023] Open
Abstract
The log-normal distribution, often used to model animal abundance and its uncertainty, is central to ecological modeling and conservation but its statistical properties are less intuitive than those of the normal distribution. The right skew of the log-normal distribution can be considerable for highly uncertain estimates and the median is often chosen as a point estimate. However, the use of the median can become complicated when summing across populations since the median of the sum of log-normal distributions is not the sum of the constituent medians. Such estimates become sensitive to the spatial or taxonomic scale over which abundance is being summarized and the naive estimate (the median of the distribution representing the sum across populations) can become grossly inflated. Here we review the statistical issues involved and some alternative formulations that might be considered by ecologists interested in modeling abundance. Using a recent estimate of global avian abundance as a case study (Callaghan et al. 2021), we investigate the properties of several alternative methods of summing across species' abundance, including the sorted summing used in the original study (Callaghan et al. 2021) and the use of shifted log-normal distributions, truncated normal distributions, and rectified normal distributions. The appropriate method of summing across distributions was intimately tied to the use of the mean or median as the measure of central tendency used as the point estimate. Use of the shifted log-normal distribution, however, generated scale-consistent estimates for global abundance across a spectrum of contexts. Our paper highlights how seemingly inconsequential decisions regarding the estimation of abundance yield radically different estimates of global abundance and its uncertainty, with conservation consequences that are underappreciated and require careful consideration.
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Pichegru L, Vibert L, Thiebault A, Charrier I, Stander N, Ludynia K, Lewis M, Carpenter-Kling T, McInnes A. Maritime traffic trends around the southern tip of Africa - Did marine noise pollution contribute to the local penguins' collapse? THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 849:157878. [PMID: 35944629 DOI: 10.1016/j.scitotenv.2022.157878] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2022] [Revised: 07/13/2022] [Accepted: 08/03/2022] [Indexed: 06/15/2023]
Abstract
The rapid increase in seaborn trade since the 1990s has resulted in an increase in vessel-derived noise pollution, yet there is little evidence linking these activities to a decline in many marine taxa, such as seabirds. Algoa Bay, South Africa, is a marine biodiversity hotspot, providing habitats for the largest populations of endangered African Penguins (Spheniscus demersus), as well as other endangered seabirds, cetaceans and seals. The bay is situated on a major shipping route and since 2016 has hosted the first offshore ship-to-ship (STS) bunkering operations in the country, i.e. the supplying of fuel from one ship to another outside of harbours. Using Automatic Identification System (AIS) data, we estimated noise emissions from vessels as a proxy for underwater ambient noise levels within the core penguin utilisation area. Frequency of vessels using the bay doubled during our study, with numbers of bulk carriers increasing ten-fold. Ambient underwater noise levels were generally high in the bay (ca 140 dB re 1 μPa since 2015) but significantly increased by 2 dB SPL after the initiation of STS bunkering in 2016, corresponding to double the underwater noise intensity. This increase coincided with a significant and dramatic decline by 85% in penguin numbers from St Croix Island since 2016. Algoa Bay is now one of the noisiest bays in the world. This is the first study to assess the potential impact of vessel-derived underwater noise levels on a seabird population. Penguins, like marine mammal species, are known to be sensitive to marine noise pollution and urgent management interventions are required to mitigate this recent disturbance, to preserve the remaining stronghold of the African penguin and the marine mammals' populations sharing the penguins' habitat.
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Affiliation(s)
- Lorien Pichegru
- Institute for Coastal and Marine Research, Nelson Mandela University, Gqeberha 6001, South Africa.
| | - Laëtitia Vibert
- Institute for Coastal and Marine Research, Nelson Mandela University, Gqeberha 6001, South Africa
| | - Andréa Thiebault
- Institute for Coastal and Marine Research, Nelson Mandela University, Gqeberha 6001, South Africa; Université Paris-Saclay, CNRS UMR 9197, Institut des Neurosciences Paris-Saclay, 91400 Saclay, France
| | - Isabelle Charrier
- Université Paris-Saclay, CNRS UMR 9197, Institut des Neurosciences Paris-Saclay, 91400 Saclay, France
| | - Nicky Stander
- Southern African Foundation for the Conservation of Coastal Birds, Cape Town 7441, South Africa
| | - Katta Ludynia
- Southern African Foundation for the Conservation of Coastal Birds, Cape Town 7441, South Africa; Department of Biological Sciences, University of Cape Town, 7700, South Africa
| | | | - Tegan Carpenter-Kling
- Institute for Coastal and Marine Research, Nelson Mandela University, Gqeberha 6001, South Africa; BirdLife South Africa, Cape Town 8001, South Africa
| | - Alistair McInnes
- BirdLife South Africa, Cape Town 8001, South Africa; FitzPatrick Institute of African Ornithology, University of Cape Town, 7700, South Africa
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11
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Leith FW, Grigg JL, Barham BJ, Barham PJ, Ludynia K, McGeorge C, Mdluli A, Parsons NJ, Waller LJ, Sherley RB. Intercolony variation in reproductive skipping in the African penguin. Ecol Evol 2022; 12:e9255. [PMID: 36091339 PMCID: PMC9448970 DOI: 10.1002/ece3.9255] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2022] [Revised: 07/21/2022] [Accepted: 08/10/2022] [Indexed: 11/17/2022] Open
Abstract
In long‐lived species, reproductive skipping is a common strategy whereby sexually mature animals skip a breeding season, potentially reducing population growth. This may be an adaptive decision to protect survival, or a non‐adaptive decision driven by individual‐specific constraints. Understanding the presence and drivers of reproductive skipping behavior can be important for effective population management, yet in many species such as the endangered African penguin (Spheniscus demersus), these factors remain unknown. This study uses multistate mark‐recapture methods to estimate African penguin survival and breeding probabilities at two colonies between 2013 and 2020. Overall, survival (mean ± SE) was higher at Stony Point (0.82 ± 0.01) than at Robben Island (0.77 ± 0.02). Inter‐colony differences were linked to food availability; under decreasing sardine (Sardinops sagax) abundance, survival decreased at Robben Island and increased at Stony Point. Additionally, reproductive skipping was evident across both colonies; at Robben Island the probability of a breeder becoming a nonbreeder was ~0.22, versus ~0.1 at Stony Point. Penguins skipping reproduction had a lower probability of future breeding than breeding individuals; this lack of adaptive benefit suggests reproductive skipping is driven by individual‐specific constraints. Lower survival and breeding propensity at Robben Island places this colony in greater need of conservation action. However, further research on the drivers of inter‐colony differences is needed.
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Affiliation(s)
- Freddie W Leith
- Centre for Ecology and Conservation College of Life and Environmental Sciences, University of Exeter Penryn UK
| | - Jennifer L Grigg
- Centre for Ecology and Conservation College of Life and Environmental Sciences, University of Exeter Penryn UK
| | | | - Peter J Barham
- H. H. Wills Physics Laboratory University of Bristol Bristol UK.,Department of Biodiversity and Conservation Biology University of the Western Cape Cape Town South Africa
| | - Katrin Ludynia
- Southern African Foundation for the Conservation of Coastal Birds (SANCCOB) Cape Town South Africa.,Department of Biological Sciences University of Cape Town Cape Town South Africa
| | - Cuan McGeorge
- Stony Point Nature Reserve, CapeNature Betty's Bay South Africa
| | - Andile Mdluli
- Southern African Foundation for the Conservation of Coastal Birds (SANCCOB) Cape Town South Africa.,Robben Island Museum, Robben Island South Africa
| | - Nola J Parsons
- Southern African Foundation for the Conservation of Coastal Birds (SANCCOB) Cape Town South Africa
| | - Lauren J Waller
- Department of Biodiversity and Conservation Biology University of the Western Cape Cape Town South Africa.,Southern African Foundation for the Conservation of Coastal Birds (SANCCOB) Cape Town South Africa
| | - Richard B Sherley
- Centre for Ecology and Conservation College of Life and Environmental Sciences, University of Exeter Penryn UK.,FitzPatrick Institute of African Ornithology, DST-NRF Centre of Excellence University of Cape Town Cape Town South Africa
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12
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Important marine areas for endangered African penguins before and after the crucial stage of moulting. Sci Rep 2022; 12:9489. [PMID: 35676286 PMCID: PMC9177839 DOI: 10.1038/s41598-022-12969-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 05/19/2022] [Indexed: 11/09/2022] Open
Abstract
The population of the Endangered African penguin Spheniscus demersus has decreased by > 65% in the last 20 years. A major driver of this decrease has been the reduced availability of their principal prey, sardine Sardinops sagax and anchovy Engraulis encrasicolus. To date, conservation efforts to improve prey availability have focused on spatial management strategies to reduce resource competition with purse-seine fisheries during the breeding season. However, penguins also undergo an annual catastrophic moult when they are unable to feed for several weeks. Before moulting they must accumulate sufficient energy stores to survive this critical life-history stage. Using GPS tracking data collected between 2012 and 2019, we identify important foraging areas for pre- and post-moult African penguins at three of their major colonies in South Africa: Dassen Island and Stony Point (Western Cape) and Bird Island (Eastern Cape). The foraging ranges of pre- and post-moult adult African penguins (c. 600 km from colony) was far greater than that previously observed for breeding penguins (c. 50 km from colony) and varied considerably between sites, years and pre- and post-moult stages. Despite their more extensive range during the non-breeding season, waters within 20 and 50 km of their breeding colonies were used intensively and represent important foraging areas to pre- and post-moult penguins. Furthermore, penguins in the Western Cape travelled significantly further than those in the Eastern Cape which is likely a reflection of the poor prey availability along the west coast of South Africa. Our findings identify important marine areas for pre- and post-moult African penguins and support for the expansion of fisheries-related spatio-temporal management strategies to help conserve African penguins outside the breeding season.
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13
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Figel T, Coyne SP, Martin K. Sex and Age Differences in Activity Budgets in a Population of Captive African Penguins (Spheniscus demersus). J APPL ANIM WELF SCI 2021:1-9. [PMID: 34579615 DOI: 10.1080/10888705.2021.1984916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Abstract
The African penguin (Spheniscus demersus) is an endangered species that continues to experience population decline. Understanding the behavior of this species is a critical step in the conservation efforts to prevent their extinction. A comprehensive activity budget of this species has yet to be conducted in any captive population, which are critical for the Species Survival Plan (SSP) breeding programs. We performed scan sampling observations on a group of 19 penguins to construct an activity budget. We also investigated the behavioral differences between males and females, as well as between adults and juveniles. Results indicate there are minimal sex differences in time budget allocations, but there are some notable age related differences. Creating and comparing activity budgets between populations are critical for understanding animal welfare in captive settings.
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Affiliation(s)
- Trystin Figel
- Biology Department, University of Saint Joseph Connecticut, West Hartford, CT, USA
| | - Sean P Coyne
- Department of Psychology, Notre Dame of Maryland University, Baltimore, MD, USA
| | - Kirsten Martin
- Biology Department, University of Saint Joseph Connecticut, West Hartford, CT, USA
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14
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Scheun J, Miller RJ, Ganswindt A, Waller LJ, Pichegru L, Sherley RB, Maneveldt GW. Urofaecal glucocorticoid metabolite concentrations in African penguin ( Spheniscus demersus) chick populations experiencing different levels of human disturbance. CONSERVATION PHYSIOLOGY 2021; 9:coab078. [PMID: 34532057 PMCID: PMC8439262 DOI: 10.1093/conphys/coab078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 07/02/2021] [Accepted: 08/18/2021] [Indexed: 06/13/2023]
Abstract
Despite the importance of ecotourism in species conservation, little is known about the industry's effects on wildlife. In South Africa, some African penguin (Spheniscus demersus) colonies have become tourist attractions. The species is globally endangered, with population sizes decreasing over the past 40 years. As African penguin chicks are altricial and unable to move away from anthropogenic stressors, it is important to evaluate the effect of tourist activities on baseline glucocorticoid levels as a measure of potential disturbance. Chicks at three study sites within two breeding colonies (Robben Island, Stony Point), with varying levels of exposure to tourism (low/moderate/high) were monitored. Urofaecal samples were collected to determine urofaecal glucocorticoid metabolite (ufGCM) concentrations as an indication of baseline stress physiology. Morphometric measurements were taken to compare body condition between sites. Penguin chicks experiencing low, infrequent human presence had significantly higher mean (± standard deviation) ufGCM levels [1.34 ± 1.70 μg/g dry weight (DW)] compared to chicks experiencing both medium (0.50 ± 0.40 μg/g DW, P = 0.001) and high levels of human presence (0.57 ± 0.47 μg/g DW, P = 0.003). There was no difference in chick body condition across sites. These results suggest that exposure to frequent human activity may induce habituation/desensitization in African penguin chicks. Acute, infrequent human presence was likely an important driver for comparatively higher ufGCM levels in chicks, though several other environmental stressors may also play an important role in driving adrenocortical activity. Nevertheless, as unhabituated chicks experiencing infrequent anthropogenic presence showed significantly higher ufGCM levels, managers and legislation should attempt to minimize all forms of activity around important breeding colonies that are not already exposed to regular tourism. Although the results of this study are crucial for developing enhanced conservation and management protocols, additional research on the long-term effect of anthropogenic activities on African penguin physiology is required.
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Affiliation(s)
- Juan Scheun
- Department of Life and Consumer Sciences, University of South Africa, Roodepoort, 1724, South Africa
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, 0081, South Africa
- National Zoological Garden, South African National Biodiversity Institute, Pretoria, 0002, South Africa
| | - Rebecca J Miller
- Department of Biodiversity and Conservation Biology, University of the Western Cape, Bellville, 7535, South Africa
| | - Andre Ganswindt
- Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Pretoria, 0081, South Africa
| | - Lauren J Waller
- Department of Biodiversity and Conservation Biology, University of the Western Cape, Bellville, 7535, South Africa
- Southern African Foundation for the Conservation of Coastal Birds (SANCCOB), Table View, 7441, South Africa
| | - Lorien Pichegru
- DST-NRF Centre of Excellence at the Percy FitzPatrick Institute of African Ornithology and Institute for Coastal and Marine Research at the Nelson Mandela University, Port Elizabeth, 6031, South Africa
| | - Richard B Sherley
- Centre for Ecology and Conservation, University of Exeter, Penry Campus, Penryn, Cornwall, TR10 9FE, UK
| | - Gavin W Maneveldt
- Department of Biodiversity and Conservation Biology, University of the Western Cape, Bellville, 7535, South Africa
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15
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Mafunda PS, Maree L, Ganswindt A, Kotze A, van der Horst GV. Seasonal changes in reproductive anatomy and gonadal hormone concentrations of African penguins (Spheniscus demersus). Anim Reprod Sci 2020; 224:106664. [PMID: 33276291 DOI: 10.1016/j.anireprosci.2020.106664] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Revised: 11/21/2020] [Accepted: 11/23/2020] [Indexed: 02/04/2023]
Abstract
Several standard descriptions of the avian male and female reproductive tract have been reported, including effects of age, stage of reproductive maturity and gonadal hormone concentrations. Limited information on penguin reproductive biology and a lack of information on the African penguin (Spheniscus demersus) necessitated a detailed description of salient structural features of this species and provided an opportunity to evaluate seasonal changes in gonadal steroid hormone concentrations. Tissues from 36 males (adults and juveniles) and 29 females (adults and juveniles) were used for macro-anatomical descriptions and histology of the testes and ovaries. In addition, concentrations of gonadal steroid hormones for eight captive African penguins (four females and four males) were quantified during two breeding and one non-breeding season. The testes were asymmetrical, with the right testis having smaller dimensions compared to the left testis. Marked spermatogenic cellular associations and spermatid developmental stages were present in adult testes only during the breeding season. There was variation in the dimensions of the single ovary during follicular development related to the age and breeding status of the females. Testosterone, dihydrotestosterone, and estradiol concentrations fluctuated during the breeding and non-breeding periods, with males and females having similar steroid concentrations. The results from this study confirm that the breeding status in African penguins can be deduced based on testicular and ovarian histological structures. The results from the present study focused on African penguin reproductive biology should be considered in management strategies for the conservation of the species.
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Affiliation(s)
- Patrick Siyambulela Mafunda
- Department of Medical Bioscience, University of the Western Cape, Bellville, 7535, South Africa; National Zoological Garden, South African National Biodiversity Institute, Pretoria, 0001, South Africa
| | - Liana Maree
- Department of Medical Bioscience, University of the Western Cape, Bellville, 7535, South Africa; National Zoological Garden, South African National Biodiversity Institute, Pretoria, 0001, South Africa
| | - Andre Ganswindt
- National Zoological Garden, South African National Biodiversity Institute, Pretoria, 0001, South Africa; Mammal Research Institute, Department of Zoology and Entomology, University of Pretoria, Hatfield, 0028, South Africa
| | - Antoinette Kotze
- National Zoological Garden, South African National Biodiversity Institute, Pretoria, 0001, South Africa; Genetics Department, University of the Free State, Bloemfontein, 9300, South Africa
| | - Gerhard van van der Horst
- Department of Medical Bioscience, University of the Western Cape, Bellville, 7535, South Africa; National Zoological Garden, South African National Biodiversity Institute, Pretoria, 0001, South Africa.
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