Seasonal variability of copepods and cladocerans in Bahía de los Ángeles (Gulf of California) and importance of Acartia clausi as food for whale sharks

Lavaniegos, BE; Heckel, Gisela

doi:10.7773/cm.v38i1a.2017

Cited by 20 publications

(12 citation statements)

References 14 publications

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“…It is a key species in tropical areas due to its large size and tendency to swarm in high numbers, making it a good food resource for planktivorous fishes (Alvarez-Cadena, Suárez-Morales & Gasca, 1998). This species has been observed at numerous large planktivore feeding aggregation sites, including those visited by M. alfredi in eastern Australia (Couturier et al, 2013;Armstrong et al, 2016), R. typus in the Gulf of Tadjoura, Djibouti (Boldrocchi et al, 2018), both M. birostris and R. typus in the Gulf of California (Notarbartolo-di Sciara, 1988;Lavaniegos, Heckel & De Guevara, 2012), and both M. alfredi and R. typus in the Philippines (Canencia & Metillo, 2013;Yap-Dejeto et al, 2018). Undinula vulgaris is considered an indicator of the influence of neritic-oceanic waters in reef environments, and its local distribution can suggest oceanic water sources (Alvarez-Cadena, Suárez-Morales & Gasca, 1998).…”

Section: Zooplankton Composition and Sizementioning

confidence: 99%

Reef manta rays forage on tidally driven, high density zooplankton patches in Hanifaru Bay, Maldives

Armstrong

Stevens²,

Townsend

et al. 2021

PeerJ

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Manta rays forage for zooplankton in tropical and subtropical marine environments, which are generally nutrient-poor. Feeding often occurs at predictable locations where these large, mobile cartilaginous fishes congregate to exploit ephemeral productivity hotspots. Investigating the zooplankton dynamics that lead to such feeding aggregations remains a key question for understanding their movement ecology. The aim of this study is to investigate the feeding environment at the largest known aggregation for reef manta rays Mobula alfredi in the world. We sampled zooplankton throughout the tidal cycle, and recorded M. alfredi activity and behaviour, alongside environmental variables at Hanifaru Bay, Maldives. We constructed generalised linear models to investigate possible relationships between zooplankton dynamics, environmental parameters, and how they influenced M. alfredi abundance, behaviour, and foraging strategies. Zooplankton biomass changed rapidly throughout the tidal cycle, and M. alfredi feeding events were significantly related to high zooplankton biomass. Mobula alfredi switched from non-feeding to feeding behaviour at a prey density threshold of 53.7 mg dry mass m−3; more than double the calculated density estimates needed to theoretically meet their metabolic requirements. The highest numbers of M. alfredi observed in Hanifaru Bay corresponded to when they were engaged in feeding behaviour. The community composition of zooplankton was different when M. alfredi was feeding (dominated by copepods and crustaceans) compared to when present but not feeding (more gelatinous species present than in feeding samples). The dominant zooplankton species recorded was Undinula vulgaris. This is a large-bodied calanoid copepod species that blooms in oceanic waters, suggesting offshore influences at the site. Here, we have characterised aspects of the feeding environment for M. alfredi in Hanifaru Bay and identified some of the conditions that may result in large aggregations of this threatened planktivore, and this information can help inform management of this economically important marine protected area.

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Section: Zooplankton Composition and Sizementioning

confidence: 99%

Reef manta rays forage on tidally driven, high density zooplankton patches in Hanifaru Bay, Maldives

Armstrong

Stevens²,

Townsend

et al. 2021

PeerJ

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“…In this aggregation site a higher abundance of juvenile whale sharks was observed during the summer months, when most of the Gulf is influenced by the entrance of low productive‐warm water of the North Equatorial Current, which also affects other studied localities such as BLP and NAY (Páez‐Osuna et al ., 2016). It is possible that BLA plays a key role for feeding in juveniles during these warm water conditions, which could allow the growth of whale sharks and eventually sexual maturation (Lavaniegos et al ., 2012; Nelson & Eckert, 2007). In contrast, the presence of this species in NAY was related to warm water conditions, along with minimum slope and shallow waters, but with higher CHLO a concentrations and SST compared with BLP.…”

Section: Discussionmentioning

confidence: 99%

Habitat suitability ofRhincodon typusin three localities of the Gulf of California: Environmental drivers of seasonal aggregations

Petatán‐Ramírez

Whitehead

Guerrero-Izquierdo

et al. 2020

Journal of Fish Biology

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The whale shark is an endangered species that usually feeds in coastal areas of highly productive seas such as the Gulf of California, Mexico. This study aims to describe the effect of sea surface temperature, chlorophyll a, bathymetry and slope on the habitat suitability of whale sharks in three important aggregation sites of the Gulf of California. A total of 2396 records of occurrence of whale sharks were obtained from international databases and scientific literature between 1996 and 2018. These records were used for the creation of a species distribution model using MaxEnt for each of the three aggregation sites. The concentration of chlorophyll a explained 71% of the habitat suitability, followed by bathymetry and slope with a combined 17%, and sea surface temperature constituting 10% of the model. Habitat suitability was related to areas where nontargeted fisheries may impact whale sharks through bycatch, entanglement and ship strikes. The implications for the conservation of whale sharks should be considered for management decisions in terms of marine protected areas, fishing refugees or bans, and other regulations regarding fisheries activities.

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“…For the dusky dolphin Lagenorhynchus obscurus , boat presence negatively affected long-term foraging efficiency, as they stopped feeding, to travel (Dans et al, 2008). If copepod abundance is subject to dynamic and seasonal changes in Bahia de los Angeles (Lavaniegos, et al, 2012), a likely cost of disturbance to whale sharks, particularly during foraging bouts, is lowered energy intake. This potentially translates into a reduction in reproductive output or in long-term survival (Lima, 1998), with local consequences on population trends.…”

Section: Discussionmentioning

confidence: 99%

Ecotourism impacts on the behaviour of whale sharks: an experimental approach

Montero-Quintana

Vázquez-Haikin²,

Merkling

et al. 2018

Oryx

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Tourists approaching wild animals can potentially cause disturbance as a result of the perceived predation risk. Risk effects arise when prey alter their behaviour in response to predators. This response may carry costs through its impact on fitness-related activities such as foraging. We recorded behavioural responses of whale sharks Rhincodon typus to experimental vessel and swimmer approaches. We simulated the disturbance caused by ecotourism in the foraging site of this planktivorous fish in Bahia de Los Angeles, Gulf of Baja California, Mexico. Stress-related behaviours (vigilance, change of direction, diving and acceleration) were more common directly after both types of disturbance than before, in particular after approach by a swimmer. Individuals were more likely to be vigilant when they were new to the bay, but we did not find evidence of within-season behavioural habituation. Sharks were 24% more likely to forage before human stimuli than after. Our study highlights negative effects of vessel and swimmer approaches on whale shark behaviour, with a short-term increase in stress-related behaviours potentially carrying energetic costs, combined with a decrease in food intake following the disturbance. Our results indicate concerns about the impact of ecotourism on large fish species. An important next step would be to determine whether these short-term behavioural responses to the perception of predation risk negatively affect fitness. Among other guidelines, we recommend preventing swimmers from approaching if whale sharks stop feeding when a vessel approaches.

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Seasonal variability of copepods and cladocerans in Bahía de los Ángeles (Gulf of California) and importance of Acartia clausi as food for whale sharks

Cited by 20 publications

References 14 publications

Reef manta rays forage on tidally driven, high density zooplankton patches in Hanifaru Bay, Maldives

Reef manta rays forage on tidally driven, high density zooplankton patches in Hanifaru Bay, Maldives

Habitat suitability ofRhincodon typusin three localities of the Gulf of California: Environmental drivers of seasonal aggregations

Ecotourism impacts on the behaviour of whale sharks: an experimental approach

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