86 research outputs found
Diet of bottlenose dolphins (Tursiops truncatus) from the Gulf of Cadiz: Insights from stomach content and stable isotope analyses [Dataset]
No full textThe ecological role of species can vary among populations depending on local and regional differences in diet. This is particularly true for top predators such as the bottlenose dolphin (Tursiops truncatus), which exhibits a highly varied diet throughout its distribution range. Local dietary assessments are therefore critical to fully understand the role of this species within marine ecosystems, as well as its interaction with important ecosystem services such as fisheries. Here, we combined stomach content analyses (SCA) and stable isotope analyses (SIA) to describe bottlenose dolphins diet in the Gulf of Cadiz (North Atlantic Ocean). Prey items identified using SCA included European conger (Conger conger) and European hake (Merluccius merluccius) as the most important ingested prey. However, mass-balance isotopic mixing model (MixSIAR), using δ13C and δ15N, indicated that the assimilated diet consisted mainly on Sparidae species (e.g. seabream, Diplodus annularis and D. bellottii, rubberlip grunt, Plectorhinchus mediterraneus, and common pandora, Pagellus erythrinus) and a mixture of other species including European hake, mackerels (Scomber colias, S. japonicus and S. scombrus), European conger, red bandfish (Cepola macrophthalma) and European pilchard (Sardina pilchardus). These contrasting results highlight differences in the temporal and taxonomic resolution of each approach, but also point to potential differences between ingested (SCA) and assimilated (SIA) diets. Both approaches provide different insights, e.g. determination of consumed fish biomass for the management of fish stocks (SCA) or identification of important assimilated prey species to the consumer (SIA).The study was funded by Fundación Loro Parque, CEPSA (Compañía Española de Petroleos S.A.), EcoCet Project [CGL2011-25543] J.G. and R.dS. were funded by the Spanish Ministry of Economy and Competitiveness through the Severo Ochoa Programme for Centres of Excellence in R+D+I [SEV-2012-0262]. A.M. and L.N. were partly supported by the Portuguese Foundation for Science and Technology [SFRH/BPD/64889/2009 and SFRH/BD/51416/2011]. Project ECOBOGUE-P11RNM7467 was funded by “Consejería de Economía, Innovación y Ciencia – Junta de Andalucía.Peer reviewe
Impact of maritime traffic and whale-watching on apparent survival of bottlenose dolphins in the Strait of Gibraltar
No full textEste artículo contiene 10 páginas, 4 figuras, 1 tabla.1. The Strait of Gibraltar is an important habitat for cetaceans due to its high marine
productivity. However, it is also the second most navigated channel in the world,
subjecting cetaceans to a high level of vessel traffic, including an established
whale-watching fleet. Both maritime traffic and whale-watching activities have
been shown to impact the behaviour of cetaceans, but little is known about their
impact on the demography and dynamics of cetacean populations.
2. The aim of this study was to evaluate the impacts of both ferry traffic and whalewatching
vessels on the apparent survival probability of a bottlenose dolphin
(Tursiops truncatus) population that occurs in the Strait.
3. A Bayesian hierarchical mark–recapture modelling approach was applied to 8 years
of photo-identification data (2002–2009). Apparent annual survival probability
was negatively correlated with ferry traffic, which explained >70% of temporal
variation in survival, in contrast to whale-watching, the effect of which was almost
negligible. Despite these results, other natural and human-related factors are
likely to drive apparent survival in the study area.
4. Abundance increased between 2002 and 2005, and then decreased between
2006 and 2009, while local per-capita recruitment decreased from 2004 until the
end of the study period. These shifts correlated temporally with the construction
of a large harbour on the Moroccan coast, which increased maritime traffic significantly,
including a 40% increase in ferry traffic that regularly transited the Strait.
5. These results highlight the need to better understand the impact of maritime traffic
on the demography of the dolphin population in the Strait, in order to implement
evidence-based conservation regulations in a region of high cetacean
occurrence.Funds were partially provided by the Spanish Ministry of Economy
and Innovation (ref. CGL2009-08298), Loro Parque Foundation,
CEPSA, the Spanish Ministry of the Environment, Fundación
Biodiversidad and two EU LIFE programme grants (ref.
LIFE07NAT/E/000732 and LIFE02NAT/E/8610). R. de Stephanis was
supported by the Spanish Ministry of Economy and Competitiveness
(Severo Ochoa SEV2012-0262; Juan de la Cierva programme).Peer reviewe
Ecology and conservation of cetaceans in southern iberian waters
No full textThis thesis fills important gaps of knowledge that will help to develop a proper conservation strategy for cetaceans in southern Iberian waters. We were able to define different ecological management units for bottlenose dolphins (Chapter 3) that may assist in the implementation of specific conservation strategies for each of the units. Dietary information of bottlenose dolphins in the Gulf of Cádiz (Chapter 4) as for common dolphins in the Strait of Gibraltar and Alboran Sea (Chapter 6) is now firstly available. With this information, we assessed the prey consumption by common dolphins in the Alboran Sea (Chapter 6), highlighting the potential competition with local fisheries. Hence, new marine protected areas were proposed in conjunction with a threat-based strategy to preserve the endangered common dolphin population of the Alboran Sea (Chapter 7). In addition, this thesis revealed that cetacean species can partition their trophic and spatial niche to allow them to coexist (Chapter 5). Further, we provide essential values for the reconstruction of cetacean diets through stable isotope analysis that can be used worldwide to properly assess assimilated preys (Chapter 1), making also available a great amount of otolith-fish size relationships (Chapter 2), extremely useful for predator-prey studies. Overall, the importance of this thesis mainly resides in providing important information for a better conservation of cetaceans in southern Iberian waters, but also applicable to other locations where marine top predators are under study. This is an important step forward in the study of ecology and conservation of cetaceans and at the same time, opens new questions to be solved.Esta tesis constituye una mejora sustancial en el conocimiento sobre la ecología de los cetáceos al sur de la península ibérica que permitirá desarrollar estrategias de conservación más adecuadas para este grupo de especies. Pudimos definir diferentes unidades de manejo ecológico de delfines mulares a través de un enfoque multidisciplinar (Capítulo 3) que permitirán la implementación de estrategias de conservación específicas para cada unidad. Por primera vez determinamos la dieta de los delfines mulares del Golfo de Cádiz (Capítulo 4) así como la de los delfines comunes del Estrecho de Gibraltar y el Mar de Alborán (Capítulo 6). Con esta información, evaluamos el consumo de presas por los delfines comunes en el Mar de Alborán (Capítulo 6), destacando la potencial competencia con las pesquerías locales. Para la correcta conservación de la amenazada subpoblación de delfines comunes del Mar de Alborán se propusieron nuevas áreas marinas protegidas junto con una estrategia basada en combatir las amenazas a nivel de cuenca (Capítulo 7). Además, esta tesis reveló que las especies de cetáceos pueden dividir su nicho trófico y espacial para permitir la coexistencia (Capítulo 5). Asimismo, proporcionamos valores esenciales para la reconstrucción de la dieta de cetáceos a través del análisis de isótopos estables que se pueden utilizar a nivel mundial para una correcta evaluación de las presas asimiladas (Capítulo 1). Paralelamente hacemos disponible una gran cantidad de regresiones entre el tamaño del otolito y el tamaño del pez que nos permite reconstruir la longitud de las presas ingeridas por los cetáceos (Capítulo 2). Esta información no tan solo es útil para la reconstrucción de la dieta ingerida por cetáceos sino que es extremadamente útil para el estudio de la dieta de otros depredadores. En general, la importancia de esta tesis reside principalmente en proporcionar información clave para mejorar las estrategias de conservación de los cetáceos al sur de la península Ibérica, pero también dicha información es aplicable a otras zonas de estudio. Este es un importante paso adelante en el estudio de la ecología y la conservación de los cetáceos y, al mismo tiempo, abre nuevas preguntas por resolver
Demografía y estructura de las poblaciones de calderones comunes (Globicephala melas) en el Mediterráneo español
No full textPrograma de doctorado: Sanidad AnimalLos calderones comunes (Globicephala melas) se encuentran en la parte superior de la red trófica marina. Por lo tanto, su estado de conservación en el Catálogo Español de Especies Amenazadas (CEEA) puede ser considerado como un indicador del buen estado ambiental del medio marino, requerido por el instrumento de planificación europeo de las Estrategias Marinas. Entre Irlanda e Italia, se identificaron cuatro poblaciones de calderones comunes. En el Atlántico, las dos poblaciones simpátricas del golfo de Vizcaya tienen una variabilidad genética alta, mientras que la del estrecho de Gibraltar y la del Mediterráneo son bajas
El valor económico no consumitivo de la vida salvaje: el caso de tres especies de cetáceos
No full textThe conservation of wildlife is one of the most pressing issues in the current times, but wildlife conservation economic values have often been largely ignored due to an absence of market prices, as setting an economic value on biodiversity or whole ecosystems can be challenging. Nevertheless, valuing wildlife can be of great significance to improve decision-making in the conservation field, as it can provide a complementary perspective based on economic principles. Whale-watching provides an opportunity for the economic valuation of wildlife. Specifically, it offers a framework in which the economic revenue allows the economic valuation of the targeted cetaceans to be estimated through the direct and indirect expenditure of the tourists who purchase whale-watching tours. Here, we performed an economic analysis based on population abundances of the three main species targeted by the whale-watching companies in the Strait of Gibraltar (Spain): long-finned pilot whales (Globicephala melas), common dolphins (Delphinus delphis) and killer whales (Orcinus orca). These species generated a total annual income of €4,089,056, €1,876,833, and €505,389, respectively, and each individual would generate an average of €14,048, €951, and €36,099 each year, respectively. Incorporating life expectancy, this corresponded to a total population value of €112,426,185, €16,685,147, and €19,171,107, respectively, over their lifetime. These values provide an idea of the potential contribution of cetaceans to the local economy but only represent their non-consumptive value based on tourism. Our results reinforce the idea that a sustainable, high-quality whale-watching culture, under ACCOBAMS High-Quality Whale-Watching requirements, should be promoted to ensure a sustainable industry, stable economic income and the viability of cetacean populations in the Strait of Gibraltar.La conservación de la vida salvaje es uno de los retos clave del mundo actual. Sin embargo, los valores económicos derivados de la conservación de la vida salvaje a menudo han sido pasados por alto debido a la ausencia de precios de mercado, ya que asignar un valor económico a la biodiversidad o a ecosistemas enteros puede ser complejo. No obstante, valorar la vida salvaje puede ser de gran importancia para mejorar la toma de decisiones en el campo de la conservación, ya que puede proporcionar una perspectiva complementaria basada en principios económicos. El avistamiento de cetáceos brinda una oportunidad para realizar este tipo de valoración económica. Específicamente, ofrece un marco en el cual los ingresos económicos generados permiten la evaluación y estimación del valor económico de los cetáceos objetivo basado en el gasto directo e indirecto de los turistas que realizan tours de avistamiento de cetáceos. En este estudio, realizamos un análisis económico basado en las abundancias poblacionales de las tres principales especies objetivo de las compañías de avistamiento de cetáceos en el Estrecho de Gibraltar (España): calderones comunes (Globicephala melas), delfines comunes (Delphinus delphis) y orcas (Orcinus orca). Estas especies generaron respectivamente un ingreso total anual de 4.089.056 €, 1.876.833 € y 505.389 €, donde cada individuo generaría un promedio de 14.048 €, 951 € y 36.099€ cada año. Al incorporar la esperanza de vida, esto se correspondió con un valor total de la población de 112.426.185 €, 16.685.147 € y 19.171.107 € a lo largo de su vida. Estos valores brindan una idea de la contribución potencial de los cetáceos a la economía local, pero solo representan su valor no consumitivo basado en el turismo. Nuestros resultados refuerzan la idea de que se debe promover una cultura de avistamiento de cetáceos sostenible y de alta calidad, bajo los requisitos de observación de cetáceos de alta calidad de ACCOBAMS, para garantizar una industria sostenible, ingresos económicos estables y la viabilidad de las poblaciones de cetáceos en el Estrecho de Gibraltar
Estudio de las poblaciones de cetáceos y detección de Zonas Especiales de Conservación para los cetáceos en el entorno marino de Jaizkibel y aguas adyacentes
No full textSharp decreases in survival probabilities in the long‑fnned pilot whales in Strait of Gibraltar
No full textEste artículo contiene 9 páginas, 3 tablas, 1 figura.The Strait of Gibraltar has some of the highest maritime activity in the world. Its populations of cetaceans are threatened
by noise, chemical pollution, and collisions by the many boats crossing the strait. One of the greatest threats identifed in
cetaceans in the Mediterranean are epizootics that severely afect the most sensitive vital rate in long-lived species: adult
survival. By a multi-event analysis of a 16-year database of long-fnned pilot whale photo identifcation capture–recapture
data, we analysed adult survival in the Strait of Gibraltar’s resident population and evaluated the possible efects of epizootics
on this vital rate. We identifed the large efect of a morbillivirus epizootic that occurred in 2006–2007, but we also revealed
a second collapse in survival in 2011, probably due to another morbillivirus epizootic. These episodes seem to afect sexes
diferently, with females being less afected than males. Interestingly, the morbillivirus epizootic not only sharply decreased
survival after the episode, but the efect extended over time, probably showing post-epizootic sequelae. These disease outbreaks have increased during the last decades worldwide and could be linked to anthropogenic threats such as organochlorine
contamination. This may explain the high frequency of epizootics in the Gibraltar area. We warn about the conservation
status of this long-fnned pilot whale population and recommend the application of measures to reduce contamination on
this nutrient-rich area to improve conditions for many marine species inhabiting this area.e. This study was funded by
the Spanish Ministry of Science (CGL2017-85210) and by Agence
Erasmus+France.
Funding were partially provided by the AEI, MCIN and
FEDER funds (CGL2017-85210), Fundacion Loro Parque, Fundación
Biodiversidad, and by Agence Erasmus+ France. We would also like
to thank the University of Perpignan Via Domitia and CEAB-CSIC
to hold MP internship.Peer reviewe
Expanding protected areas to encompass the conservation of the endangered common dolphin (Delphinus delphis) in the Alboran Sea
No full text8 pages, 4 figures, 2 tables, supplementary data https://doi.org/10.1016/j.marenvres.2021.105305The Natura 2000 network is the centerpiece of the European Union conservation strategy to safeguard priority species and habitats. The question of whether other co-occurring species of conservation concern may also benefit from this network, however, remains largely unknown. Here, we used a systematic approach (MARXAN) for i) evaluating if the current Natura 2000 network in the Alboran Sea (western Mediterranean Sea), initially proposed to protect the common bottlenose dolphin (Tursiops truncatus) and priority habitats, is also spatially protecting the endangered common dolphin (Delphinus delphis), and ii) identifying additional marine areas that should be protected to reach adequate conservation targets for the common dolphin. While the current Natura 2000 network encompass ca. 22% of predicted abundances for common dolphins, this percentage might be enhanced by protecting coastal areas nearby the Strait of Gibraltar. However, dolphins and fisheries largely overlap spatially nearby the coastline, and only segregate in offshore areas that represent the marginal distribution of the species. Thus, conservation decision-makers must achieve a trade-off between cetacean conservation and fisheries by combining an area-based approach (i.e., new protected areas close to the Strait of Gibraltar) together with a basin-wide threat-based approach (e.g., regulation of fisheries)This publication is produced within the framework of the project MarxanCETALBORAN, a project co-financed by the European Maritime and Fisheries Fund throught the Pleamar Program (Fundación Biodiversidad, Ministerio para la Transición Ecológica). In addition, this work was partially funded by Fundación Loro Parque, CEPSA (Compañía Española de Petroleos S.A.), EcoCet Project [CGL 2011-25543], LIFE + Indemares [LIFE07NAT/E/000732], LIFE “Conservación de Cetáceos y Tortugas de Murcia y Andalucía” [LIFE02NAT/E/8610]. FR was funded by Spanish Government through the ‘Severo Ochoa Centre of Excellence’ accreditation obtained by ICM-CSIC [CEX2019-000928-S]Peer reviewe
Exploring fidelity of Sardines (Sardina pilchardus) to feeding grounds in the Atlantic Moroccan waters using stable isotope analyses (C, N) and otolith microchemistry
No full textThe Atlantic Moroccan waters (21°-29°N) are part of the Canary Current Large Marine Ecosystem and are enriched by highly productive upwelling systems. Sardine (Sardina pilchardus) is both the most abundant forage fish in this area and the most heavely fish species [1]. It is described as a migratory small pelagic species that feeds on phyto and zooplankton. From population genetics studies (allozyme and micostellite DNA), it is assumed that our area of interest houses a single population [2] with at least two spawning areas [3].
In order to study trophic position and fidelity to feeding grounds, we investigated sardines from two distant sites: 23-24°N and 28-29°N, using stable isotope analysis (d15N and d13C) and otolith microchemistry. Isotopic analyses were performed on delipidated muscle subsamples, and plankton samples (150µm mesh net), using a continuous flow isotope-ratio mass spectrometry. The trophic position of sardine is compared to those of major forage fish of the same area. Otholith microelements concentrations (Li, B, Mg, Mn, Zn, Sr, Ba, Pb and U) were measured by ICP-MS laser on transects from nucleus to the edge of the otoliths of sardines. Chemical analyses were carried out on five individuals per site.
Sardine individuals from the different sites showed significantly different trophic position for both C and N isotopes. The northern individuals were depleted in d15N (1‰ difference), suggesting that phytoplankton is more important in their diet. The d13C values showed greater differences (~3‰) for both Sardines and zooplankton between the two sites, pointing high fidelity for sardine individuals towards the feeding grounds. While Anchovy and Horse Mackerel showed a similar pattern with sardine for δ13C, chub mackerel showed no significant differences between the two areas suggesting a higher seasonal migratory behavior for this species. Sardine Microelements profiles reinforced the sedentary behavior hypothesis for sardine. The Barium (Ba) profiles were the most discriminant: the concentration range was 7× higher for the southern area where upwelling intensity is higher [4]
- …
