Urban development in coastal cities is highly threatening for marine coastal wildlife, especially endangered species like the marine otter Lontra felina, whose habitat is restricted to coastal rocky areas along the coast of Peru and Chile. In this work, we determine the habitat loss through the use of remote sensors along the coast of Lima, the capital of Peru with a high number of inhabitants and a nearly uncontrolled urban growth. We evaluated three localities: Punta Corrientes, Pucusana, and Ancón using satellite images for two different years: 2016 vs. 2023. The analysis of potential habitat and habitat loss followed the CORINE Land Cover technical guide adapted to Peru. Two algorithms for land classification were tested, SVM and Random Forest. Both had Kappa values over 0.60; however, SVM had the best precision on pixel classification. Among the categories analyzed, “rocky outcrops” showed a reduction in all the three areas but in Ancón and Pucusana there was over 20% of loss. On the contrary, the category “continuous urban fabric” increased over 23% in Ancón and 13.55% in Pucusana. The change in land cover and use was statistically significant in Ancón (p < 0.005; χ2 = 8.0302, df = 3). The loss of “rocky outcrops” has a statistically significant change for all the localities (p < 0.005; χ2 = 6.229, df = 2). Our results provide evidence that the coastline is changing in Ancón and Pucusana. The physical reduction of coastline is critical for marine otters, since their activity is limited to the rocky shoreline, both marine and terrestrial. Marine otters inhabit all of the three locations, however, the main modification occurs in Ancón and Pucusana; the loss of the available habitat would involve both habitat loss and reduction of habitat quality.
Cetacean diversity in the Windward Dutch Caribbean remains poorly known, with only six species previously reported in its waters. By contrast, cetacean diversity is well documented in neighbouring islands, including Puerto Rico and the Virgin Islands, as well as in parts of the Lesser Antilles, where 23 species are known to occur. Based on 40 days of systematic boat-based surveys conducted over five years, supplemented by opportunistic sightings, we update the information of cetacean diversity within the Exclusive Economic Zones of Saba, St. Maarten, and St. Eustatius. Each record was individually reviewed, and first-time species reports were validated through photographic evidence or confirmation by researchers with recognized expertise. A total of 124 cetacean sightings were recorded, documenting 17 species in the Windward Dutch Caribbean. These findings demonstrate that this previously understudied area harbors a cetacean diversity comparable to that of neighboring Antillean islands and provide new insights into coastal cetacean distribution in the region. This work establishes a baseline for future research and conservation planning around these islands and across the broader Northern Lesser Antilles.
Beach monitoring is an essential method for documenting marine mammal strandings, and gathering valuable information on individual and population dynamics. This study reports occurrences of pinniped strandings along the coast of São Paulo state (23-25° S), Southeastern Brazil, with the aim of updating species records, analyzing seasonal, annual, and spatial stranding patterns and identifying the sex and maturity class of the individuals. Data were collected between 1980 and 2023, initially through sporadic records and non-systematic monitoring. From 2015 onward, data were systematically collected via daily monitoring conducted by the Santos Basin Beach Monitoring Project (PMP-BS). Throughout the study period, a total of seven species were recorded in the state, representing both the Otariidae and Phocidae families: South American sea lion (Otaria flavescens), South American fur seal (Arctocephalus australis), Subantarctic fur seal (Arctocephalus tropicalis), Antarctic fur seal (Arctocephalus gazella), southern elephant seal (Mirounga leonina), leopard seal (Hydrurga leptonyx), and crabeater seal (Lobodon carcinophaga). The findings revealed that immature males of South American fur seal and mature males of Subantarctic fur seal were the most frequently encountered individuals. Strandings occurred year-round, with the highest number of occurrences observed in winter, the only season during which all listed species were recorded. Furthermore, the southern coast of São Paulo state exhibited the highest concentration of strandings. This study represents the first detailed account of pinniped records along the São Paulo coast.
The giant otter (Pteronura brasiliensis) is a charismatic, South American, social carnivore, and the largest otter species in the world. Historically, giant otters were almost extirpated due to the wildlife skin trade and are currently considered as Endangered. Using the Range Wide Priority Setting methodology, we (a group of 33 giant otter experts) updated the species’ historical range (9,021,590 km2), modelled an adjusted and more conservative aquatic historical range of 2,813,539 km2, systematized 5,593 giant otter distribution points across the range, and identified geographic areas for which there was expert knowledge (63%), including areas where giant otters no longer occur (19%), and geographic areas where giant otter presence is uncertain due to a lack of expert knowledge (37%). To prioritize conservation actions into the future and identify existing giant otter population strongholds, we used expert knowledge to identify 22 of the most important areas for the conservation of the species (i.e., Giant Otter Priority Conservation Units [GOPCUs]) that cover 29% of the historical range, and range in size from 1,367 km2 to 829,152 km2. In general, GOPCUs were relatively large and approximately 35% of the total GOPCU area is already designated as protected areas. Using the Range Wide Priority Setting results, we make a series of recommendations towards the long-term conservation of this iconic aquatic species.
Population abundance and trends of the humpback whale Breeding Stock G (BSG) were estimated from land-based monitoring at the Santa Elena Peninsula tip, Ecuador (2°11.35′S, 81°0.63′W). The study was conducted between May and December from 2010 to 2024. The effort included 3,736.5 hours of observation, during which 7,528 whale groups were recorded. Boat-based data were used to complement land-based observations. The first whales arrived in early May, and the last departed in late December. The northbound migration peak occurred in late June. The observation rate increased from 0.699 whales per hour (whales/h, SD = 0.63) in 2010 to 4.19 whales/h (SD = 3.45) in 2024, concordant with a population increase. Based on an estimated intrinsic population growth rate of 0.107, we estimated the population to be 27,362 whales in 2024. The calf production rate was 0.165 (SD = 0.04). The average annual survival rate of the population was 0.956 (SD = 0.212). These findings suggest that the population has recovered and is likely approaching carrying capacity. The observed interannual variability was associated with ENSO’s impact on whale migration behavior. During strong El Niño years (2015 and 2023), the birth rate increased, likely because a portion of the population did not migrate or reach the breeding area, artificially inflating the rate. In the years following a strong El Niño (2016 and 2024), the birth rate decreased, while the population increased considerably as whales that did not migrate the previous year joined with pregnant females in the former year. This relationship between migration behavior and environmental conditions warrants further analysis, particularly in light of increasing ocean climate variability and its implications for population assessments.
This study presents the age structure and growth patterns, spatial and seasonal distribution, and anthropic interactions of franciscana dolphin Pontoporia blainvillei, using data from stranded individuals through a nine-year effort of daily monitoring on the northern coast of São Paulo, an important area within the Franciscana Management Area (FMA IIa). The main results are compatible with the literature for the region, i.e., asymptotic growth, sexual maturity, and seasonality of stranding events, except with a higher frequency of calves and adults on the north coast of São Paulo than observed in other areas. Our results strengthen the relevance of this FMA as a region with a high occurrence of franciscana strandings, in addition to highlighting the high occurrence of the species’ interaction with gillnet fishing. Approximately 60% of registered individuals presented evidence of fishing interactions. Ubatuba was the area with the highest concentration of events, underlining the need for studies on carcass drift dynamics, population structure, and local fishing, to determine the mortality cause of this species and the significant fishing threat locations.
Killer whales (Orcinus orca) prey on various whale species in the world’s oceans. Here, we present seven cases of mysticetes preyed upon by killer whales on the continental coast of the Gulf of California. Five fin whales (Balaenoptera physalus), one Bryde’s whale (B. brydei), and one gray whale (Eschrichtius robustus) were preyed upon and partly consumed in the same way over 17 years in different areas of the coast of Sonora, Mexico. The methodology included direct inspection of stranded or floating whale carcasses, analysis of predation marks, and review of videos provided by local fishermen. The notorious way in which whales were preyed upon by cutting and ripping large portions of blubber and skin layers is similar to how the whalers used to flense whale carcasses. No internal organs were consumed, although the tongue was consumed in each event. Most attacks occurred in shallow waters, coinciding with high productivity/upwelling areas. These events provide evidence on killer whales’ hunting behavior and consumption patterns, highlighting the importance of shallow waters and selectivity of the skin/blubber and tongue as preferential food, which contributes to understanding the trophic interactions of cetaceans in the Gulf of California.
Coastal ecosystems around the world are facing increasing mercury pollution from various anthropogenic activities, which are affecting many aquatic mammals such as dolphins. Lake Maracaibo receives discharges of industrial water, wastewater, pesticides and herbicides from runoff, and constant oil spills; these discharges include several contaminants. In this paper, we highlight the extent of mercury accumulation in the soft tissues of Guiana dolphins and some fish species from southern Lake Maracaibo. A total of 17 fish species were analyzed. All but one of the species had traces of mercury, but only the mercury level in Gobioides broussonnetii (mean ± standard deviation = 0.9209 ± 0.0134 mg kg-1 wet weight (ww)) exceeded the limit established as safe for human consumption. In Guiana dolphins, mercury levels in four of six individuals exceeded the maximum limit considered safe for human consumption (0.5 mg kg-1 ww), with the highest level of 2.9611 ± 0.1637 mg kg-1 ww in the liver of one individual, suggesting biomagnification through diet and possible adverse effects in this species. It is important to note that the dolphins from which samples were collected were juveniles. There is evidence of a correlation between mercury accumulation and the size and age of dolphins, emphasising the ecological risks posed by anthropogenic pollutants. The wider ecological impacts, including threats to endangered fish species and public health risks associated with mercury-contaminated marine resources are also discussed. This study emphasises the urgent need for comprehensive management strategies to reduce mercury pollution and to protect coastal ecosystems and public health.
In Brazil, the Amazon River dolphin or boto (Inia geoffrensis) is considered a charismatic creature of the Amazonian culture and freshwater biodiversity, which attracts a lot of tourists searching for unique experiences with wildlife. Under several threats, boto’s population is declining and opportunities/alternatives to develop conservation actions are needed, advised, and urgent. This study aimed to investigate from local riverside perspective if the dolphin-watching Community-Based EcoTourism (CBET) is a good conservation alternative for boto. By applying semi-structured interviews and participant observation methods, we studied the perception of 68 riverside people from the Mamirauá Sustainable Development Reserve (MSDR), central Amazon. Some 88.3% of respondents considered the dolphin-watching tourism as an important conservation measure, since it helps in the dissemination of local knowledge about the species, restrains ‘outsider’ fishermen presence, and generates alternative income to communities. The same respondents understand as important the conservation of boto, and 68% said that keeping ecological relations between animal and environment helps in the conservation of its habitats. The economic benefits of dolphin-watching tourism in the MSDR were reported by 32.8% respondents. Community-based wildlife tourism is one of the widely used tools to promote species conservation and their habitats, when following good practices and promoting awareness, economic benefits, and scale up impacts. The results from this study provide information which may support strategies for the touristic management and conservation of botos in the Amazon.
A twenty-five year old dataset of parasites in long-beaked and short-beaked common dolphins (Delphinus spp.), using fisheries as an opportunistic platform of access, registered seven species of helminths and one epizoite, being a unique dataset for the Southeast Pacific. Sampling was conducted in 1985-2000 at six fishing ports in Peru and Ecuador where cetaceans were landed from interactions with small-scale fisheries. From a total of 473 common dolphins examined, we identified helminths including three species of Trematoda: Nasitrema globicephalae, Pholeter gastrophilus, and Braunina cordiformis; three species of Nematoda, including Anisakis spp., Crassicauda spp., and Halocercus sp.; and two cestodes, Tetrabothrius forsteri and Clistobothrium delphini. No acanthocephalans were observed. No statistically significant sexual and ontogenetic variation in helminth prevalence was detected, after which samples were pooled. The highest prevalences in the long-beaked common dolphin (n = 440) were observed for N. globicephalae (87.9%, 29 infested/33 sampled) in cranial sinuses, Crassicauda sp1. (80%, 4/5) in mammary glands, followed by Cl. delphini (28.6%, 2/7) in the blubber, and P. gastrophilus (23%, 26/113) in the pyloric stomach. Although comparative testing was unfeasible due to minimal samples of short-beaked common dolphin (n = 33), several of the same helminth species were found; but not N. globicephalae nor B. cordiformis. No cyamids were encountered while pseudo-stalked barnacles Xenobalanus globicipitis were common. Although no new (global) helminth host records were revealed for common dolphins, this study presents a first checklist of parasites separately for the Southeast Pacific long-beaked and short-beaked common dolphins. Future work should include exhaustive laboratory-based necropsies, enhanced sampling of the short-beaked form, review data from recent parasite collections, focus on intermediate hosts and parasitic pathology, including potential human health impact from consumption of small cetaceans.
