Linking small pelagic fish and cetacean distribution to model suitable habitat for coastal dolphin species, Delphinus delphis and Tursiops truncatus, in the Greek Seas (Eastern Mediterranean)

Giannoulaki, Marianna; Markoglou, Evangelia; Valavanis, Vasilis D.; Alexiadou, Paraskevi; Cucknell, Anna; Frantzis, Alexandros

doi:10.1002/aqc.2669

Cited by 34 publications

(41 citation statements)

References 59 publications

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“…This temporal transition between different seasons may affect factors such as SST being statistically revealed as significant in our models. Bibliographically speaking, unavailable variables such as the occurrence of prey may affect the fine-scale species distribution [58,59]. Furthermore, one of the main limitations concerning the model-based analysis used is the risk of bias in abundance estimation due to model misspecification [27].…”

Section: Discussionmentioning

confidence: 99%

Model-Based Distribution and Abundance of Three Delphinidae in the Mediterranean

Karamitros

Gkafas

Giantsis

et al. 2020

Animals

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Monitoring of Delphinidae species population patterns in the Mediterranean Sea was carried out in a sequence of surveys employing different approaches. Data from seven-year surveys with small catamaran sailing boats were analyzed under model-based approaches. Density Surface Models were used to produce spatial distribution prediction of three Delphinidae species (Stenella coeruleoalba, Tursiops truncatus, and Delphinus delphis) in an extended study area covering much of the Mediterranean Sea. A classical distance sampling protocol was applied in order to calculate the detection probability of clusters. Static (depth, slope, distance from the coast, and distance from isobaths of 200 m) and nonstatic (sea surface temperature and chlorophyll) variables were used to predict the species distribution/abundance in a generalized additive model context. Stenella coeruleoalba was found to be the dominant species, with an extended distribution in the study area; its abundance was significantly affected by both depth and distance. Tursiops truncatus and Delphinus delphis illustrated a significant abundance correlation with depth and chlorophyll, respectively, while both species showed a robust longitude correlation. Our model pinpoints the significance of nondesigned transect line surveys, suggesting the importance of specific habitat areas for future monitoring and conservation aspects of marine mammals.

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Section: Discussionmentioning

confidence: 99%

Model-Based Distribution and Abundance of Three Delphinidae in the Mediterranean

Karamitros

Gkafas

Giantsis

et al. 2020

Animals

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“…Common dolphins in Greece (and elsewhere in the Mediterranean) normally prefer continental shelf waters (Bearzi et al, ; ; Frantzis et al, ; Giannoulaki et al, ), where they target epipelagic schooling fish such as European anchovy, Engraulis encrasicholus , and the European pilchard, Sardina pilchardus (Bearzi et al, ; ; Bearzi, Politi, Agazzi, & Azzellino, ). In the Gulf of Corinth, the unusual preference for deep waters documented in this study is consistent with the hypothesis of common dolphins having modified their behaviour to associate with larger striped dolphin groups.…”

Section: Discussionmentioning

confidence: 99%

Modelling dolphin distribution within an Important Marine Mammal Area in Greece to support spatial management planning

Bonizzoni¹,

Furey

Santostasi

et al. 2019

Aquatic Conservation

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Understanding marine mammal distributions is essential for conservation, as it can help identify critical habitat where management action can be taken. The semi‐enclosed Gulf of Corinth, Greece, has been identified as an Important Marine Mammal Area by the International Union for Conservation of Nature (IUCN) Marine Mammal Protected Areas Task Force, based on the regular occurrence of odontocete populations. A 7‐year (2011–17) dataset of boat‐based surveys was used to model and predict the distribution of striped dolphins, Stenella coeruleoalba, common dolphins, Delphinus delphis, and common bottlenose dolphins, Tursiops truncatus, in the entire Gulf (2400 km2). Multiple geographic, bathymetric, oceanographic, and anthropogenic variables were incorporated in a combined generalized additive model and generalized estimation equation (GAM‐GEE) framework to describe dolphin occurrence and produce distribution maps. Modelling indicated that striped and common dolphins prefer deep waters (>300 m) in the central and southern part of the Gulf, whereas bottlenose dolphins prefer shallow waters (<300 m) and areas close to fish farms along the northern–central shore. Model‐based maps of the predicted distribution identified a preferred habitat encompassing most of the Gulf, also revealing: (i) hot spots of dolphin distribution covering about 40% of the Gulf's surface; (ii) an almost complete overlap of striped and common dolphin distribution, consistent with the hypothesis that common dolphins modified their habitat preferences to live in mixed species groups with striped dolphins; (iii) a clear partitioning of striped/common and bottlenose dolphin habitat; and (iv) the important role played by fish farms for bottlenose dolphins, consistent with studies conducted elsewhere in Greece. Evidence provided by this study calls for area‐specific and species‐specific management measures to mitigate anthropogenic impacts.

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“…Seven cetacean species are resident in the Aegean Sea ( Specifically, the delineation of important areas for each of the seven species was based on distribution data obtained through field observations over the last 15 years, habitat suitability modeling (Giannoulaki et al, 2016), and expert judgment (for optimal polygon limits). The aforementioned field observations include geo-referenced sightings of cetacean groups which were mainly recorded during dedicated visual-acoustic surveys, or as opportunistic observations accompanied by photographic material for the identification/verification of species.…”

Section: Cetaceamentioning

confidence: 99%

Assembling Ecological Pieces to Reconstruct the Conservation Puzzle of the Aegean Sea

et al. 2017

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The effective conservation of marine biodiversity through an integrated ecosystem-based management approach requires a sound knowledge of the spatial distribution of habitats and species. Although costly in terms of time and resources, acquiring such information is essential for the development of rigorous management plans and the meaningful prioritization of conservation actions. Located in the northeastern part of the Mediterranean, the Aegean Sea represents a stronghold for marine biodiversity. However, conservation efforts are hampered by the apparent lack of spatial information regarding marine habitats and species. This work is the first to address this knowledge gap by assembling, updating, and mapping information on the distribution of key ecological components. A range of data sources and methodological approaches was utilized to compile and complement the available data on 68 ecological features of conservation interest (58 animal species, six habitat categories, and four other vulnerable ecological features). A standardized data evaluation procedure was applied, based on five semi-quantitative data quality indicators in the form of a pedigree matrix. This approach assessed the sufficiency of the datasets and allowed the identification of the main sources of uncertainty, highlighting aspects that require further investigation. The overall dataset was found to be sufficient in terms of reliability and spatiotemporal relevance. However, it lacked in completeness, showing that there are still large areas of the Aegean that remain understudied, while further research is needed to elucidate the distribution patterns and conservation status of several ecological features; especially the less charismatic Sini et al.Aegean Sea Conservation Puzzle ones and those found in waters deeper than 40 m. Moreover, existing conservation measures appear to be inadequate to safeguard biodiversity. Only 2.3% of the study area corresponds to designated areas for conservation, while 41 of the ecological features are underrepresented in these areas. Considering the high geomorphological complexity and transnational character of the Aegean Sea, this study does not offer a complete account of the multifaceted diversity of this ecoregion. Instead, it represents a significant starting point and a solid basis for the development of systematic conservation plans that will allow the effective protection of biodiversity within an adaptive management framework.

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Linking small pelagic fish and cetacean distribution to model suitable habitat for coastal dolphin species, Delphinus delphis and Tursiops truncatus, in the Greek Seas (Eastern Mediterranean)

Cited by 34 publications

References 59 publications

Model-Based Distribution and Abundance of Three Delphinidae in the Mediterranean

Model-Based Distribution and Abundance of Three Delphinidae in the Mediterranean

Modelling dolphin distribution within an Important Marine Mammal Area in Greece to support spatial management planning

Assembling Ecological Pieces to Reconstruct the Conservation Puzzle of the Aegean Sea

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