Ecological and Behavioral Traits of Apex Predators in Oceanic Insular Ecosystems: Advances and Challenges in Research and Conservation

Editorial

14 August 2023

Editorial: Ecological and behavioral traits of apex predators in oceanic insular ecosystems: advances and challenges in research and conservation

Filipe Alves

Nuno Queiroz

and

Patrick G. R. Jodice

1,716 views

3 citations

Editors

Filipe Alves

Center for Marine and Environmental Sciences (MARE)

Patrick Jodice

United States Geological Survey (USGS), United States Department of the Interior

Nuno Queiroz

Centro de Investigacao em Biodiversidade e Recursos Geneticos (CIBIO-InBIO)

Impact

Original Research

12 June 2023

Response of cetaceans to fluctuations of pelagic fish stocks and environmental conditions within the Celtic Sea ecosystem

Andrea Fariñas-Bermejo

, 5 more and

Graham J. Pierce

3,361 views

2 citations

Original Research

22 February 2023

Site fidelity and population parameters of pantropical spotted dolphins in the Eastern Caribbean through photographic identification

Baptiste Courtin

, 7 more and

Benjamin de Montgolfier

2,742 views

2 citations

For reference, black dashed curve is the probability density of seafloor depth for the full study area (see Figure 1B) and black solid curve is the probability density of seafloor depth for all marine mammal sightings, identified and unidentified (see Figure 2A). The three vertical red lines indicate depths of 200, 500, and 1000 m, respectively. Marine mammal sighting data from Palacios (1999b); Palacios and Salazar (2002); Palacios (2003), Félix et al. (2011), and Cantor et al. (2017), used with permission or under Creative Commons licenses CC BY and CC BY-NC. Bathymetry data from SRTM15+ (Tozer et al., 2019), available from https://topex.ucsd.edu/WWW_html/srtm15_plus.html.

Review

14 February 2023

Priorities for ecological research on cetaceans in the Galápagos Islands

Daniel M. Palacios

and

Mauricio Cantor

5,337 views

6 citations

Original Research

15 November 2022

Population estimates of photo-identified individuals using a modified POPAN model reveal that Raja Ampat’s reef manta rays are thriving

Edy Setyawan

, 11 more and

Rochelle Constantine

The 6.7-million-hectare Raja Ampat archipelago is home to Indonesia’s largest reef manta ray (Mobula alfredi) population and a representative network of nine marine protected areas (MPAs). However, the population dynamics of M. alfredi in the region are still largely unknown. Using our photo-identification database, we fitted modified POPAN mark-recapture models with transience and per capita recruitment parameters to estimate key demographic characteristics of M. alfredi from two of Raja Ampat’s largest MPAs: Dampier Strait and South East (SE) Misool. A total of 1,041 unique individuals were photo-identified over an 11-year period (2009–2019) from Dampier Strait (n = 515) and SE Misool (n = 536). In our models, apparent survival probabilities and per capita recruitment rates were strongly linked with El Niño–Southern Oscillation (ENSO) events. Our models also estimated high apparent survival probabilities and significant increases in (sub)population sizes in both MPAs over a decade. In Dampier Strait, the estimated population size increased significantly (p = 0.018) from 226 (95% CI: 161, 283) to 317 (280, 355) individuals. Likewise, the estimated population size in SE Misool increased significantly (p = 0.008) from 210 (137, 308) to 511 (393, 618) individuals. Regardless of variation in the percentage change in population size between years throughout the study, the estimated overall population change shows a compound growth of 3.9% (0.7, 8.6) per annum in Dampier Strait and 10.7% (4.3, 16.1) per annum in SE Misool. Despite the global decline in oceanic sharks and rays due to fishing pressure in the last five decades, our study demonstrates the positive impact of a suite of long-term conservation efforts, coupled with the influence of ENSO events, on increasing M. alfredi abundance in Raja Ampat MPAs. Our study also underscores the importance of long-term monitoring to evaluate the effectiveness of conservation management measures on manta ray populations. Our modification of the standard POPAN model by incorporating per capita recruitment and transience parameters represents an important advance in mark-recapture modelling that should prove useful when examining other manta ray populations and other highly migratory species that are likely to have a substantial percentage of transient individuals.

8,434 views

9 citations

, 2013; Prieto et al., 2014; González-Garcia et al., 2022) and Madeira from 2014 to 2019. For the Azores, analysis was restricted to the peak season, from June to September, while for Madeira was year-round. The figures show the probability that an individual identified in the study area at any time will be identified again in the study area some time lag after. The line represents the best-fitting model according to Table 2, and the vertical bars indicate standard errors calculated using the bootstrap method.

Original Research

08 December 2022

Unraveling site fidelity and residency patterns of sperm whales in the insular oceanic waters of Macaronesia

Rita Ferreira

, 6 more and

Filipe Alves

3,651 views

4 citations

Original Research

04 November 2022

Phenological divergence, population connectivity and ecological differentiation in two allochronic seabird populations

Fernando Medrano

, 5 more and

Jacob González-Solís

2,806 views

5 citations

Original Research

27 October 2022

Oceanographic gradients explain changes in the biological traits of nesting seabird assemblages across the south-eastern Pacific

Joao B. Gusmao

, 1 more and

Marcelo M. Rivadeneira

1,702 views

1 citations

95 %, and the confidence interval (COI) curve.

Original Research

27 July 2022

Long-Term Monitoring of In-Water Abundance of Juvenile Pelagic Loggerhead Sea Turtles (Caretta caretta): Population Trends in Relation to North Atlantic Oscillation and Nesting

Thomas Dellinger

, 1 more and

Marko Radeta

2,861 views

1 citations

Original Research

05 July 2022

The Multi-Annual Residency of Juvenile Smooth Hammerhead Shark in an Oceanic Island Nursery

Pedro Afonso

, 4 more and

Jorge Fontes

The increased risk of local extinction becomes critical for sharks depending on the narrow and isolated coastal habitats of oceanic islands. This includes large pelagic oceanic sharks that use such habitats as nurseries, as previously hypothesized for the smooth hammerhead Sphyrna zygaena, the least known of cosmopolitan large hammerhead sharks. We used a combination of acoustic and satellite telemetry in a juvenile population of Faial and Pico islands, Azores, mid-north Atlantic, to confirm if this isolated archipelago holds nurseries, and to answer questions related to their function and spatial–temporal stability. Our long-term acoustic tracking data showed a cluster of individual core home ranges in specific areas of north shore Faial, and surface positions from five Argos-linked tagged individuals also showed a clustering overlap in those areas for up to 1 year. These patterns seem to reveal a true habitat preference within the Faial-Pico island (sub) population of juvenile smooth hammerhead shark, and thus constitute strong evidence for this area to be considered a nursery. Some individuals remained in this nursery for up to 4 years, especially during summers. Sharks also showed a strong diel behavior, typically using the inshore nurseries during the day and moving further offshore during the night, during which they increased activity and dove deeper, most possibly to feed. We speculate that a combination of increased feeding opportunities, expanded trophic niche, and reduced predatory pressure may be a key evolutionary driver for the existence, prolonged use, and even preference of coastal nurseries at oceanic islands by juvenile smooth hammerhead shark. Given that these nurseries may constitute essential fish habitat for this species, they should be explicitly included in spatial management measures at the local and regional scales, as they may also play a role of greater importance to the north Atlantic population of this oceanic species.

4,263 views

10 citations

Original Research

30 March 2022

Tracing Seal Predation Back to the Source Colony of Their Penguin Prey: A Trace Element and Stable Isotope Analysis

Sarah-Lena Reinhold

, 4 more and

Rebecca R. McIntosh

2,664 views

2 citations

Original Research

30 March 2022

Deciphering the Trophic Ecology of Three Marlin Species Using Stable Isotope Analysis in Temperate Waters Off Southeastern Australia

Tristan A. Guillemin

, 2 more and

Jane E. Williamson

Understanding the unique feeding behaviours of oceanic fish, such as marlin, is key to their effective management. Marlin are notoriously difficult to study, however, and the limited research on marlin feeding shows that diet can vary greatly between species and geographic regions. One region where marlin feeding behaviours are particularly poorly understood are temperate eastern Australian waters. This study collected marlin tissue from game fishing tournaments between latitudes 32°43′06.5″S/152°08′50.1″E to 34°40′12.9″S/150°51′34.3″E between 2010 and 2021, and used stable isotope analysis (SIA) to assess the trophic ecology of the three species of marlin occurring in the region: black (Istiompax indica), blue (Makaira nigricans), and striped (Kajikia audax) marlin. All species had similar δ¹³C values, but δ¹⁵N differed between species, with higher variability observed in blue marlin than in the other two species. Sulphur isotopes were key in identifying the relative contribution of coastal or benthic influences on marlin diet, with δ³⁴S suggesting that blue marlin had less coastal/benthic dietary influence than black or striped marlin. Incorporation of δ³⁴S into SIA for marlin is thus recommended for future studies. Some differences in isotope values across locations and dates were found, however, the uneven sample sizes due to the opportunistic sampling limited the ability to understand spatial or seasonal differences. These findings show that marlin followed similar dietary trends to conspecifics in other regions despite temperate eastern Australian waters being one of the few with three marlin species commonly co-occuring. This suggests that interspecies resource competition is not a major force driving the demography of these species in eastern Australian waters. This research highlights a need for specific management strategies at a species level, particularly for blue marlin. Future research incorporating prey isoscapes and baselines assessed over a wider range of marlin sizes is suggested to further improve our knowledge and capacity to manage the marlin of eastern Australian waters.

4,063 views

6 citations

Systematic Review

17 March 2022

The Status of Marine Megafauna Research in Macaronesia: A Systematic Review

Ashlie J. McIvor

, 4 more and

João Canning-Clode

Cumulative number of publications in marine megafauna research per archipelago through time: (A) marine mammals, (B) chondrichthyes, (C) large-bodied osteichthyes, and (D) marine turtles. Silhouettes derived from Phylopic (http://phylopic.org).

Marine megafauna serve valuable ecological and economical roles globally, yet, many species have experienced precipitous population declines. The significance of marine megafauna is particularly evident in Macaronesia, a complex of oceanic archipelagos in the Northeast Atlantic Ocean. Macaronesian islands provide important habitats for marine megafauna species, in turn supporting considerable regional economic activity (e.g., ecotourism and fisheries). Despite this, concerted efforts to manage marine megafauna throughout Macaronesia have been limited. This systematic review provides the first description of the trends in marine megafauna research in this unique insular ecosystem, to provide a better understanding of taxa-specific research needs and future directions for conservation. We identified and validated 408 peer-reviewed publications until 2021 following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) criteria. Literature was dominated by marine mammal research conducted in the northern archipelagos (Azores, Madeira, and Canary Islands) and marine turtle research conducted in Cabo Verde. Much less research focused on large-bodied fish, especially in Madeira and Canary Islands, leaving some of the most vulnerable species regionally data deficient. Research across scientific disciplines focused more on biological studies than management and policy, and anthropogenic impacts were quantified more frequently on mammals or turtles and less on fishes. By identifying gaps in our knowledge of megafauna in relation to threats faced by these organisms, we offer taxa-specific recommendations for future research direction. Although, overall our results indicate that determining population level connectivity should be a major research priority among many marine megafauna species as this information is vital to numerous management strategies, including marine protected areas. In this review, we present a basis of understanding of the current work in Macaronesia, highlighting critical data gaps that are urgently needed to guide the next steps toward establishing conservation priorities for marine megafauna in the region.

6,752 views

17 citations