Composition and behavior of mixed-species foraging groups of reef fish in the Lakshadweep islands, India

Author(s):  
Anne Heloise Theo ◽  
Kartik Shanker

Mixed-species foraging groups of reef fishes, although relatively common in occurrence, have historically received little attention. Most studies on this topic have been descriptive accounts of specific associations. In this study, we collected data on mixed-species foraging groups seen in the Lakshadweep islands, resulting in a dataset of 1289 groups. Data was collected from both reefs and lagoons of three islands (Kadmat, Kavaratti, and Agatti) within the Lakshadweep Archipelago over a period of three years. Cluster analysis revealed nine categories based on species composition in groups: parrotfish, juveniles, surgeonfish (small), surgeonfish (large), Anampses spp., wrasses, Parupeneus macronema, Parupeneus barberinus, and other goatfish groups. The clusters are named based on the nuclear species or most frequently seen species within the groups. These groups are distinct not only in terms of composition but also other parameters such as behavior (shoaling or attendant groups), habitat affinity, and group cohesion. Groups comprising herbivorous species such as parrotfish and surgeonfish were almost entirely shoaling in nature (large groups without nuclear individuals), whereas goatfish and wrasses tended to form smaller attendant associations. Groups also occupied different habitat types; for example, parrotfish and P. barberinus groups were seen mostly in lagoons while surgeonfish, wrasses, and P. macronema groups were more abundant on reefs. Our findings suggest that mixed-species foraging groups in fishes are comprised of distinct compositional categories that vary in behavior, cohesion, and habitat affinity.

2021 ◽  
Vol 4 ◽  
Author(s):  
Mélissa Jaquier ◽  
Camille Albouy ◽  
Wilhelmine Bach ◽  
Conor Waldock ◽  
Viriginie Marques ◽  
...  

Islands have traditionally served as model systems to study ecological and evolutionary processes (Warren et al. 2015) and could also represent a relevant system to study environmental DNA (eDNA). Isolated island reefs that are affected by climatic threats would particularly benefit from cost- and time-efficient biodiversity surveys to set priorities for their conservation. Among time efficiency methods, eDNA has emerged as a novel molecular metabarcoding technique to detect biodiversity from simple environmental samples even in remote marine environments. However, eDNA monitoring techniques for marine environments are at a developmental phase, with a few remaining unknowns related to DNA residence time and movement. In particular, the redistribution of eDNA, via ocean currents, could blur the composition signal and its association with local environmental conditions (Goldberg et al. 2016). Here, we investigated the detection variation of eDNA along a distance gradient across four islands in the French Scattered Islands. We collected 30 L of surface water per filter at an increasing distance from the islands reefs (0m, 250m, 500m, 750m). Using a metabarcoding protocol, we used the teleo primers to target a fraction of 12S mitochondrial DNA to detect Actinopterygii and Elasmobranchii. We then applied a sequence clustering approach to generate Molecular Taxonomic Units (MOTUs), which were assigned to a taxonomic group using a reference database. By assigning eDNA sequences to species using a public reference database, we classified species according to their preferred habitat types between benthic/demersal and pelagic. Our results show no significant relationship between distance and MOTUs richness for both habitat types. By using a Joint Species Distribution Modelling approach (JSDM, Hierarchical Modelling of Species Communities), we retained the multidimensional information captured by eDNA and detect species- and family-specific responses to distance (Fig. 1). We showed that benthic MOTUs were found in closer proximity to the reef, while typical pelagic MOTUs were found at greater distances from the reef. Hence, MOTU-level analyses coupled with JSDM were more informative that when aggregating it into coarser richness. Altogether, our eDNA distance sampling gradient detected an ecological signal of habitat selection by fish species, which suggest that eDNA could help understand the behavior of species and their distribution in marine environments at a fine spatial scale.


1982 ◽  
Vol 6 (3) ◽  
pp. 147-152 ◽  
Author(s):  
Joseph W. Roggenbuck ◽  
Alan E. Watson ◽  
George H. Stankey

Abstract Wilderness managers need information about visitor preferences and behavior if they are to protect wilderness experiences and resources. Linville Gorge, Shining Rock, and Joyce Kilmer/Slickrock wilderness users have somewhat different perceptions of wilderness problems, but too many people in certain places, a lack of information about use, litter, and destruction of vegetation are commonly mentioned. Wilderness users expect few contacts with other groups, especially with large groups and at campsites. Use controls are generally supported, and visitors favor unobtrusive management strategies over direct regulation.


The Condor ◽  
2001 ◽  
Vol 103 (1) ◽  
pp. 38-44 ◽  
Author(s):  
Katia Lombardini ◽  
Robert E. Bennetts ◽  
Christophe Tourenq

Abstract We examined habitat use by Little Egrets (Egretta garzetta) and Cattle Egrets (Bubulcus ibis) that nest together in mixed-species colonies in the Camargue of southern France. We explored the relative use of seven habitat types in relation to their availability and tested the hypothesis that selection of habitat types was related to foraging success, with the prediction that increased foraging success in a given habitat corresponded with increased use of that habitat type. Ricefields and other agricultural habitats were used more than expected by Cattle Egrets, an invasive species in southern Europe; whereas Little Egrets, which are native to the Camargue, tended to select natural freshwater marshes and lagoons. Results were consistent with the hypothesis that increasing use of habitats corresponded with higher foraging success for both species. However, when this analysis was restricted to habitats with sufficient numbers of birds to enable estimates of biomass intake, the association was no longer apparent for Little Egrets.


2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
Aymer Andrés Vásquez-Ordóñez ◽  
Inge Armbrecht ◽  
Gabriela Pérez-Lachaud

Eucharitidae are parasitoids that use immature stages of ants for their development.KapalaCameron is the genus most frequently collected in the Neotropics, but little is known about the biology and behavior of any of the species of this genus. We aimed to evaluate the effect of habitat type on eucharitid parasitism and to contribute to the knowledge of the host-parasite relationship betweenKapalasp. and the poneromorph antEctatomma ruidum(Roger) in Colombia. TwentyE. ruidumcolonies were extracted from two different habitat types (woodland and grassland), and larvae and cocoons (pupae) were examined in search for parasitoids in different stages of development. Globally, 60% of the colonies were parasitized, with 1.3% of larvae and 4% of pupae parasitized. Planidia (first-instar larvae), pupae, and adults of the parasitoid were observed. All of the pupae and adult parasitoids belonged toKapala iridicolorCameron. All the colonies collected in the woodlands were parasitized and contained more parasitized larvae (2%) and parasitized cocoons (8%) than those collected in grasslands (4/12 parasitized colonies, 0.5% parasitized larvae, 0.8% parasitized cocoons). The relationship observed between habitat type and parasitism prevalence is a novel aspect of the study of eucharitid impact on ant host populations.


The Auk ◽  
2003 ◽  
Vol 120 (1) ◽  
pp. 82-95
Author(s):  
Patrick J. Hart ◽  
Leonard A. Freed

Abstract Mixed-species flocks of native and introduced birds were studied for four years in an upper elevation Hawaiian rain forest. Those flocks were characterized by strong seasonality, large size, low species richness, high intraspecific abundance, a lack of migrants, and a general lack of territoriality or any sort of dominance hierarchy. There was high variability among years in patterns of occurrence at the species level, and high variability within years at the individual level. These flocks are loosely structured social groupings with apparently open membership. The fluid, unstable movement patterns, high degree of variability in size and composition, and lack of positive interspecific associations are not consistent with the “foraging enhancement” hypothesis for flocking. Two resident, endangered insectivores, the Akepa (Loxops coccineus) and Hawaii Creeper (Oreomystis mana) served as “nuclear” species. Flock composition was compared between two study sites that differed significantly in density of these two nuclear species. Flock size was similar at the two sites, primarily because the nuclear species were over-represented relative to their density. This observation suggests that birds are attempting to achieve a more optimal flock size at the lower density site.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Kamal Raj Gosai ◽  
Eben Goodale

Abstract Background Mixed-species flocks (MSFs) have been well sampled in the South Asia, but there has been as yet surprisingly little work on MSFs of Nepal, despite a diverse and well-studied avifauna. We surveyed MSFs in two forest types in and around the Important Bird Area of Chitwan National Park in Nepal, between 150 and 800 m a.s.l., to provide a first description of the composition of MSFs in this area. We also aimed to understand which species should be considered ‘nuclear species’, important to forming MSFs or leading them forward. Results In total, we collected records on 222 MSFs that included 100 species, and 6097 individuals. The MSFs were similar to worldwide patterns in being dominated by leaf-gleaning, non-terrestrial insectivores. However, the MSFs were more dominated by canopy species than usual, and did not have a clear gregarious, understory leading species. Rather drongos (Family Dicruridae) and minivets (Family Campephagidae, Genus Pericrocotus) acted as leaders, and a cluster analysis of composition showed one group of large body size MSFs particularly characterized by the presence of the Greater Racket-tailed Drongo (Dicrurus paradiseus). Conclusions Drongos are known to provide both costs and benefits to other flock participants: they are aggressive birds that can steal food, and manipulate other species with their vocalizations, but at the same time they are ‘sentinel species’ that produce information about predation risk other species can use. This study demonstrates that drongos can be considered nuclear species for some types of MSFs, despite the potential costs of their presence. MSFs led by sentinel species thus may form in Asia, as well as in the Neotropics.


2017 ◽  
Vol 284 (1852) ◽  
pp. 20162758 ◽  
Author(s):  
Maud C. O. Ferrari ◽  
Mark I. McCormick ◽  
Bridie J. M. Allan ◽  
Douglas P. Chivers

Coral reefs are biodiversity hotpots that are under significant threat due to the degradation and death of hard corals. When obligate coral-dwelling species die, the remaining species must either move or adjust to the altered conditions. Our goal was to investigate the effect of coral degradation on the ability of coral reef fishes to assess their risk of predation using alarm cues from injured conspecifics. Here, we tested the ability of six closely related species of juvenile damselfish (Pomacentridae) to respond to risk cues in both live coral or dead-degraded coral environments. Of those six species, two are exclusively associated with live coral habitats, two are found mostly on dead-degraded coral rubble, while the last two are found in both habitat types. We found that the two live coral associates failed to respond appropriately to the cues in water from degraded habitats. In contrast, the cue response of the two rubble associates was unaffected in the same degraded habitat. Interestingly, we observed a mixed response from the species found in both habitat types, with one species displaying an appropriate cue response while the other did not. Our second experiment suggested that the lack of responses stemmed from deactivation of the alarm cues, rather than the inability of the species to smell. Habitat preference (live coral versus dead coral associates) and phylogeny are good candidates for future work aimed at predicting which species are affected by coral degradation. Our results point towards a surprising level of variation in the ability of congeneric species to fare in altered habitats and hence underscores the difficulty of predicting community change in degraded habitats.


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