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

PeerJ ◽  
2021 ◽  
Vol 9 ◽  
pp. e11992
Author(s):  
Asia O. Armstrong ◽  
Guy M.W. Stevens ◽  
Kathy A. Townsend ◽  
Annie Murray ◽  
Michael B. Bennett ◽  
...  
Keyword(s):  
Tidal Cycle ◽  
Feeding Behaviour ◽  
Linear Models ◽  
Marine Protected Area ◽  
Movement Ecology ◽  
Environmental Parameters ◽  
Zooplankton Biomass ◽  
Foraging Strategies ◽  
Calculated Density ◽  
Zooplankton Dynamics

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.

Diets and foraging behaviour of red and eastern grey kangaroos in arid shrub land: is feeding behaviour involved in the range expansion of the eastern grey kangaroo into the arid zone?

2004 ◽  
Vol 26 (2) ◽  
pp. 169 ◽  
Author(s):  
TJ Dawson ◽  
KJ McTavish ◽  
BA Ellis
Keyword(s):  
Feeding Behaviour ◽  
Foraging Behaviour ◽  
Arid Zone ◽  
Foraging Strategies ◽  
Foraging Patterns ◽  
Grey Kangaroo ◽  
Macropus Rufus ◽  
Dietary Niche ◽  
Domestic Stock ◽  
Total Feeding

Eastern grey kangaroos (Macropus giganteus) have expanded into arid areas usually the habitat of red kangaroos (Macropus rufus). Extra watering sites for domestic stock is the suggested reason. However, changes in vegetation also have occurred due to grazing from domestic stock. We investigated the foraging strategies of M. giganteus and M. rufus in arid rangeland to see if these are involved in the range changes. Foraging patterns were similar, with both species mostly foraging at night; total feeding times were the same. M. giganteus and M. rufus had differing diets, though there was considerable overlap of 81 - 87%. Both species were highly selective, having similar narrow dietary niche breaths. Differences in plant preferences occurred and though both species had a preference for grass that of M. giganteus was higher. A larger foregut in M. giganteus reinforces its focus on grass. M. rufus also selected dicot forbs and malvaceous sub-shrubs. Both kangaroos showed avoidance of abundant chenopod shrubs (saltbushes and bluebushes) and trees. It is likely that the changes to arid-zone vegetation, with a shift to grass and annual dicot forbs, has been important for the expansion of M. giganteus, possibly combined with the greater availability of water.

Ecology of periphyton in a meltwater stream ecosystem in the maritime Antarctic

2003 ◽  
Vol 15 (2) ◽  
pp. 189-201 ◽  
Author(s):  
JOSEF ELSTER ◽  
ONDREJ KOMAREK
Keyword(s):  
Linear Models ◽  
Environmental Parameters ◽  
Dry Weight ◽  
Physico Chemical ◽  
Cell Mortality ◽  
Periphyton Biomass ◽  
Negative Relationships ◽  
Microscope Slides ◽  
Petrified Forest

The ecology of two meltwater streams on King George Island, Ornithologists Creek (with penguin rookeries close to its lower reaches) and Petrified Forest Creek (a highly oligotrophic system), was studied during the 1996–97 summer season. To estimate seasonal productivity of the periphyton and to establish which environmental parameters influenced periphyton growth most strongly, two types of artificial substrata (fibreglass nets – ash-free dry weight (AFDW), and microscope slides – Chlorophyll a (Chl a)) were tested in situ. Thus relative periphyton productivity (RPP) reflects algal colonization and growth as well as losses due to cell mortality and abrasive action of moving sediments. The Petrified Forest Creek was more productive (AFDW = 108.63 μg cm−2 d−1, Chl a = 0.35 μg g cm−2 d−1) than the Ornithologists Creek (AFDW = 69.90 μg cm−2 d−-1, Chl a = 0.26 μg cm−2 d−1). RPP differed both along the streams, and during the season. Significant positive or negative relationships (generalized linear models) were found between RPP and streamwater ‘physico-chemical parameters’ and ‘geomorphological-geographical characteristics’ of the streams' catchments. In addition, in the lower reaches of both streams almost no active colonization or growth was recorded. In the Petrified Forest Creek, the periphyton biomass was so high that mainly passive organic matter deposition occurred. By contrast, in the lower reach of Ornithologists Creek, periphyton colonization and growth was around zero, being negatively influenced by penguin excrement. Ornithologists Creek was richer in nutrients (DIN, DRP), which also fluctuated more widely along its length and throughout the season, than in the Petrified Forest Creek. Parameters associated with the inorganic carbon cycle of the streamwater reflect higher RPP in Petrified Forest Creek. Moreover, RPP was higher in stream reaches with higher amounts of gravel boulders on the bottom.

scholarly journals Human eating behaviour in an evolutionary ecological context

2002 ◽  
Vol 61 (4) ◽  
pp. 517-526 ◽  
Author(s):  
Stanley J. Ulijaszek
Keyword(s):  
Food Availability ◽  
Feeding Behaviour ◽  
Homo Sapiens ◽  
Eating Behaviour ◽  
High Energy ◽  
Homo Erectus ◽  
High Energy Density ◽  
Foraging Strategies ◽  
Economic Transformations ◽  
Feeding Adaptations

Present-day human eating behaviour in industrialised society is characterised by the consumption of high-energy-density diets and often unstructured feeding patterns, largely uncoupled from seasonal cycles of food availability. Broadly similar patterns of feeding are found among advantaged groups in economically-emerging and developing nations. Such patterns of feeding are consistent with the evolutionary ecological understanding of feeding behaviour of hominids ancestral to humans, in that human feeding adaptations are likely to have arisen in the context of resource seasonality in which diet choice for energy-dense and palatable foods would have been selected by way of foraging strategies for the maximisation of energy intake. One hallmark trait of human feeding behaviour, complex control of food availability, emerged with Homo erectus (19 × 106-200 000 years ago), who carried out this process by either increased meat eating or by cooking, or both. Another key trait of human eating behaviour is the symbolic use of food, which emerged with modernHomo sapiens(100 000 years ago to the present) between 25 000 and 12 000 years ago. From this and subsequent social and economic transformations, including the origins of agriculture, humans have come to use food in increasingly elaborate symbolic ways, such that human eating has become increasingly structured socially and culturally in many different ways.

scholarly journals Diurnal feeding strategies of the Ferruginous Duck (Aythya nyroca) in Lake Tonga (Northeastern Algeria)

2019 ◽  
Vol 27 (1) ◽  
pp. 85-98 ◽  
Author(s):  
Khalil Draidi ◽  
Badis Bakhouche ◽  
Naouel Lahlah ◽  
Imed Djemadi ◽  
Mourad Bensouilah
Keyword(s):  
Feeding Behaviour ◽  
Foraging Behaviour ◽  
Time Budget ◽  
Search Time ◽  
Environmental Parameters ◽  
Feeding Strategies ◽  
A Minor ◽  
Northeastern Algeria ◽  
Foraging Time ◽  
Minor Activity

Abstract Although the Ferruginous Duck (Aythya nyroca) has thoroughly been studied, the foraging behaviour of this species is still not completely known. In the present paper we studied the diurnal feeding behaviour of ducks. We monitored the annual cycle of birds through two fieldtrips per month. The instantaneous behaviour of birds was recorded in regular 30-minute intervals from 7 a.m. to 4:30 p.m., amounting a total of 456 observation hours. Food searching activity corresponds to a quarter of the total diurnal time budget of the Ferruginous Duck. Foraging behaviour was classified into five categories dominated by the “diving”, which is almost 45.61% of the total search time. Foraging activities at the water surface considered to be secondary activities, including feeding by “bill”, “neck and head”, and “beak and head” in a rate of 19.86%, 14.53%, and 13.98%, respectively. The “toggle” remains a minor activity and represents only 5.99% of foraging time. The feeding behaviour of this species correlated to several environmental parameters (rainfall, temperature and wind velocity), and linked to the group size of ducks visiting the lake. Regarding the food intensity, our results show the highest values for “bill and head” behaviour. “Diving” has the longest feeding interval (16.16±14.1 minutes), while foraging by “bill” has the shortest (0.69 ± 0.48 minutes).

Feeding behaviour of the common dolphinfish Coryphaena hippurus: older fish use more complex foraging strategies

2015 ◽  
Vol 95 (6) ◽  
pp. 1277-1284 ◽  
Author(s):  
José De Anchieta C.C. Nunes ◽  
Renato H. A. Freitas ◽  
José A. Reis-Filho ◽  
Miguel Loiola ◽  
Cláudio L.S. Sampaio
Keyword(s):  
Feeding Behaviour ◽  
Visual Cues ◽  
Prey Availability ◽  
Learning Experience ◽  
Foraging Strategy ◽  
Foraging Strategies ◽  
Size Classes ◽  
Coryphaena Hippurus ◽  
The Common ◽  
Floating Objects

The common dolphinfish (Coryphaena hippurus) is widely distributed and represents an important part of the currently exploited fishery resources. This species’ feeding behaviour, however, is poorly understood. This study aimed to investigate the feeding behaviour of dolphinfish and the effect of body size (and the consequently aggregated learning experience) on the strategies used for capturing their prey. Observations were made from an oil platform in north-eastern Brazil. Dolphinfish length was visually estimated and classified into three size classes. The following foraging strategies were observed in our study: ‘active chasing’, ‘leaping out’, ‘swimming in circles’, ‘surf’, ‘using floating objects’ and ‘cleaning turtle carapaces’. The most frequently used foraging strategy was ‘active chasing’, suggesting a strong preference of dolphinfish in using visual cues during predation. Smaller size-classes of dolphinfish did not perform the ‘swimming in circles’ and ‘surf’ strategy, probably due to a lack of learning experience, since further social interactions could be needed in order to show this strategy. Smaller dolphinfish regularly showed the ‘using floating objects’ as a foraging strategy, probably reflecting an opportunistic behaviour. The smallest individuals were using more simple strategies, to chase smaller prey that could have different and less complex escape strategies. It indicates learning experience could play an important role into the dolphinfish ontogeny, moving towards more complex foraging strategies throughout their lives. Independently of the age class, the dolphinfish displayed a varied repertory of foraging strategies, maximizing hunting success in the open ocean, a hostile pelagic environment with a low prey availability.

scholarly journals Dugong foraging behavior on tropical intertidal seagrass meadows: the influence of climatic drivers and anthropogenic disturbance

Hydrobiologia ◽  
2021 ◽  
Author(s):  
Anugrah A. Budiarsa ◽  
H. H. De Iongh ◽  
Wawan Kustiawan ◽  
Peter M. van Bodegom
Keyword(s):  
Wind Speed ◽  
Linear Models ◽  
Belowground Biomass ◽  
Foraging Strategies ◽  
Fishing Activity ◽  
Factors Affecting ◽  
Seagrass Meadows ◽  
Seagrass Biomass ◽  
Tropical Areas ◽  
Intertidal Seagrass

AbstractForaging strategies of dugongs in tropical areas are not yet well understood, and that is particularly true for grazing of fast-growing pioneer seagrass meadows in the intertidal zones. In this study, we investigated the driving factors affecting the number of grazing tracks in intertidal seagrass meadows caused by small herds of dugongs in Balikpapan Bay, Indonesia. We investigated seven intertidal seagrass meadows for which the dynamics of seagrass biomass, the ratio aboveground to belowground biomass, and the number of grazing tracks were recorded and measured based on monthly intervals over a year. Seagrass features showed a significant relationship with wind speed, precipitation, desiccation time, the distance of the grazing sward to a residential area, and fishing activity based on multiple (generalized) linear models. While the intertidal seagrass meadows consisted of 5 species in total, only Halodule pinifolia patches were grazed. Dugong feeding tracks were found in four of the seven sites. The strong variation in the number of tracks throughout the year was significantly affected by seagrass biomass of seagrass, location and wind speed. Our results show how the interplay of site conditions related to both shelter (wind speed) and food availability (seagrass biomass) determines its suitability for dugongs.

scholarly journals Unravelling the foraging behavior of the southern stingray, Hypanus americanus (Myliobatiformes: Dasyatidae) in a Southwestern Atlantic MPA

2019 ◽  
Vol 17 (2) ◽  
Author(s):  
Renato H. A. Freitas ◽  
Aline A. Aguiar ◽  
Ana Karina C. H. A. Freitas ◽  
Sergio M. Q. Lima ◽  
Jean L. Valentin
Keyword(s):  
Foraging Behavior ◽  
Tidal Cycle ◽  
Feeding Habits ◽  
Decision Makers ◽  
Foraging Strategies ◽  
Ontogenetic Shift ◽  
Southwestern Atlantic ◽  
Environmental Stimulus ◽  
Management Plans ◽  
Fernando De Noronha

ABSTRACT Previous study suggested that the southern stingray (Hypanus americanus) displays a marked ontogenetic shift in its habitat use in the Fernando de Noronha Archipelago (FNA), an attractive touristic spot in Brazil, that could be associated with changes in its feeding habits and foraging strategies. Here, we conducted underwater visual surveys (~100 h a 3 years’ study) at this site to describe the foraging behavior of the same species in details and to assess diel patterns in activity. We observed that H. americanus is capable of several complex and highly plastic behaviors (we described more than 21 of them) while foraging. The foraging events’ timing appears to be related to the size (as well as sex) of the stingrays, environment and depth. In addition, our results support a segregation of habitat mediated by the size and sex of the stingrays, but it is able to modulate its foraging repertoire based mainly on environmental stimulus. Finally, we found that H. americanus forage intermittently throughout the day and tidal cycle, yet are less active during non-crepuscular periods and at flood and ebb tides. These results, coupled with the fact that the species uses both reef and beach environments, should be considered by decision makers in management plans.

scholarly journals Experimental study protocol of the project “MOtor function and VItamin D: Toolkit for motor performance and risk Assessment (MOVIDA)”

PLoS ONE ◽  
2021 ◽  
Vol 16 (7) ◽  
pp. e0254878
Author(s):  
Valeria Belluscio ◽  
Amaranta S. Orejel Bustos ◽  
Valentina Camomilla ◽  
Francesco Rizzo ◽  
Tommaso Sciarra ◽  
...  
Keyword(s):  
Vitamin D ◽  
Motor Function ◽  
Linear Models ◽  
Environmental Parameters ◽  
Continuous Variables ◽  
Cross Sectional ◽  
Stress Injury ◽  
Recreational Athletes ◽  
Related Data ◽  
Behavioural Factors

Musculoskeletal injuries, a public health priority also in the military context, are ascribed to several risk factors, including: increased reaction forces; low/reduced muscle strength, endurance, body mass, Vitamin D level, and bone density; inadequate lifestyles and environment. The MOVIDA Project–funded by the Italian Ministry of Defence—aims at developing a transportable toolkit (assessment instrumentation, assessment protocols and reference/risk thresholds) which integrates motor function assessment with biological, environmental and behavioural factors to help characterizing the risk of stress fracture, stress injury or muscle fatigue due to mechanical overload. The MOVIDA study has been designed following the STROBE guidelines for observational cross-sectional studies addressing healthy adults, both militaries and civilians, with varying levels of physical fitness (sedentary people, recreational athletes, and competitive athletes). The protocol of the study has been designed and validated and is hereby reported. It allows to collect and analyse anamnestic, diagnostic and lifestyle-related data, environmental parameters, and functional parameters measured through portable and wearable instrumentation during adapted 6 minutes walking test. The t-test, one and two-way ANOVA with post-hoc corrections, and ANCOVA tests will be used to investigate relevant differences among the groups with respect to biomechanical parameters; non-parametric statistics will be rather used for non-normal continuous variables and for quantitative discrete variables. Generalized linear models will be used to account for risk and confounding factors.

scholarly journals Species Archetype Models of Kelp Forest Communities Reveal Diverse Responses to Environmental Gradients

Oceanography ◽  
2021 ◽  
Vol 34 (2) ◽  
pp. 92-101
Author(s):  
Rhiannon Rognstad ◽  
◽  
Andrew Rassweiler ◽  
Daniel Reed ◽  
Li Kui ◽  
...  
Keyword(s):  
Linear Models ◽  
Environmental Gradients ◽  
Kelp Forest ◽  
Environmental Parameters ◽  
Community Change ◽  
Management Tool ◽  
Marine Biodiversity ◽  
Distribution Data ◽  
Kelp Forests ◽  
Ecosystem Integrity

Assessing ecosystem integrity by monitoring populations and communities is an important management tool, but is often limited by the immense variety of species and the rarity of many of them. Grouping species by their responses to variation in the environment is one approach to choosing species to serve as effective indicators of community change. Moreover, identifying species that are characterized by similar archetypical responses to the environment increases the power to predict their occurrence and simplifies management of diverse species assemblages by focusing on a much smaller number of archetypes. To this end, we used the species archetype model (SAM) to fit generalized linear models of environmental covariates to species distribution data in order to identify environmentally correlated groups of kelp forest species in the Santa Barbara Channel region. Eighty-two species of macroalgae, invertebrates, and fish monitored in kelp forests across the channel were grouped into one of 10 archetypes based on their similar responses to environmental parameters, with water temperature emerging as one of the strongest drivers of archetype differences. Predictive maps of the distribution of species archetypes identified sites where multiple archetypes are common, indicating high diversity, as well as sites where rare species are more likely to occur. Potential indicator species were identified for each archetype. New monitoring efforts across the growing Marine Biodiversity Observation Network could use modeling approaches like SAM to guide their designs, optimizing the cost-to-benefit ratio of monitoring whole communities.

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