scholarly journals Influence of environmental parameters on habitat use by sympatric freshwater eels, Anguilla marmorata and A. japonica on Yakushima Island, Japan

2021 ◽  
Author(s):  
Yusuke Kumai ◽  
Mari Kuroki ◽  
Kentaro Morita
Keyword(s):  
Habitat Use ◽  
Current Velocity ◽  
Life Stage ◽  
Habitat Preferences ◽  
Environmental Parameters ◽  
Tropical Species ◽  
River Systems ◽  
Yakushima Island ◽  
Anguilla Marmorata ◽  
Freshwater Eels

It is known that environmental parameters, such as water depth, size of substrate material, and current velocity influence the organization of stream fish communities. However, few studies have investigated the effects of these parameters on sympatric freshwater eels. Here, the habitat use of two anguillid eels, Anguilla marmorata Quoy and Gaimard, 1824 and A. japonica Temminck and Schlegel, 1846, coexisting in the same river systems in Japan was investigated. It was found that the tropical species A. marmorata exclusively utilized habitats with larger substrate materials, fewer fallen leaves and less leaf detritus, higher current velocity, and lower turbidity than the temperate species A. japonica, and the distributions of the two anguillid eels were clearly segregated. Thus, when both species co-occur in the same river systems, clear flowing mainstems and tributaries are preferred habitats for A. marmorata, while stagnant muddy estuaries, backwater areas, irrigation channels, and reservoirs are preferred habitats for A. japonica. These habitat segregations were consistent through body-size increases and life-stage developments from elver to yellow eel and did not show ontogenetic shifts. The findings indicated that both species had strong habitat preferences, and these environmental parameters must be considered in the conservation of anguillid eels in sympatric zones.

scholarly journals Distribution and habitat use of the Madagascar Peregrine Falcon: first estimates for area of habitat and population size

2021 ◽  
Author(s):  
Luke J. Sutton ◽  
Lily-Arison Réné de Roland ◽  
Russell Thorstrom ◽  
Christopher J.W. McClure
Keyword(s):  
Habitat Use ◽  
Population Size ◽  
Habitat Preferences ◽  
High Elevation ◽  
Range Limits ◽  
Tropical Species ◽  
Peregrine Falcon ◽  
Distribution Models ◽  
The Core ◽  
Vegetation Heterogeneity

AbstractAccurately demarcating species distributions has long been at the core of ecology. Yet our understanding of the factors limiting species range limits is incomplete, especially for tropical species in the Global South. Human-driven threats to the survival of many taxa are increasing, particularly habitat loss and climate change. Identifying distributional range limits of at-risk and data-limited species using Species Distribution Models (SDMs) can thus inform spatial conservation planning to mitigate these threats. The Madagascar Peregrine Falcon (Falco peregrinus radama) is the resident sub-species of the Peregrine Falcon complex distributed across Madagascar, Mayotte, and the Comoros Islands. Currently, there are significant knowledge gaps regarding its distribution, habitat preferences and population size. Here, we use point process regression models and ordination to identify Madagascar Peregrine Falcon environmental range limits and propose a population size estimate based on inferred habitat. From our models, the core range of the Madagascar Peregrine Falcon extends across the central upland plateau of Madagascar with a patchier range across coastal and low-elevation areas. Range-wide habitat use indicated that the Madagascar Peregrine Falcon prefers areas of high elevation and aridity, coupled with high vegetation heterogeneity and > 95 % herbaceous landcover, but generally avoids areas of > 30 % cultivated land and > 10 % mosaic forest. Based on inferred high-class habitat, we estimate this habitat area could potentially support a population size ranging between 150-300 pairs. Following International Union for Conservation of Nature Red List guidelines, we recommend this sub-species be classed as Vulnerable, due to its small population size. Despite its potentially large range, the Madagascar Peregrine has specialized habitat requirements and would benefit from targeted conservation measures based on spatial models in order to maintain viable populations.

Summer stream habitat preferences of Nunavik anadromous Arctic char (Salvelinus alpinus) fry and parr

2022 ◽  
Author(s):  
Véronique Dubos ◽  
André St-Hilaire ◽  
Normand E Bergeron
Keyword(s):  
Habitat Use ◽  
Salvelinus Alpinus ◽  
Habitat Preferences ◽  
Arctic Region ◽  
Arctic Char ◽  
The Arctic ◽  
Stream Habitat ◽  
Physical Habitat ◽  
High Plasticity ◽  
Slow Velocity

Arctic char is a fish species known to occupy diverse habitats within the Arctic region. However, summer habitat use during the juvenile stage of the anadromous form is largely unknown. The present study aims to characterize fry and parr summer habitat preferences. Surveys were conducted by electrofishing, associated with physical habitat characterization on several rivers of the Ungava Bay, Nunavik, Canada. At the microhabitat and station scales, fry showed significant habitat preferences for shallow water and slow velocity. At the mesohabitat scale, fry showed a significant habitat selectivity for riffles. This habitat selectivity implies that habitat models can be built to evaluate the potential of habitat suitability for Arctic char fry. However, no significant habitat selectivity was found for parr. Parr size was nonetheless positively correlated with velocity, which was found to be a limitative factor for juvenile habitat use. This first attempt at modeling juvenile anadromous Arctic char habitat in rivers emphasizes the importance of selecting an appropriate spatial scale and reiterates the fact that parr showed relatively high plasticity in stream habitat selection.

scholarly journals Variation in Population Structures of Tropical Freshwater Eels, Anguilla Marmorata, A. Bicolor Bicolor and A. Bengalensis Bengalensis, in the Indo-Pacific

2021 ◽  
Author(s):  
Takaomi Arai ◽  
Hussein Taha
Keyword(s):  
Tropical Species ◽  
Pacific Region ◽  
Oceanic Current ◽  
Dispersion Patterns ◽  
Population Structures ◽  
Different Populations ◽  
And Migration ◽  
Current Systems ◽  
Freshwater Eels ◽  
Spawning Sites

Abstract Freshwater eels, genus Anguilla, have a distinctive catadromous life history, which could be associated with certain oceanic current systems and offshore spawning sites. Thus, migration and dispersion patterns are believed to be important factors influencing the population structures of each species. Temperate eel species are well studied, while little research has been conducted on the tropical counterparts that comprise two-thirds of all eel species. The population structures of three tropical species, A. marmorata, A. bicolor bicolor and A. bengalensis bengalensis, which are distributed widely in the Indo-Pacific region, were explored by means of DNA sequence analysis of mitochondrial cytochrome c oxidase subunit I (COI). This study found that A. bicolor bicolor had two genetically distinct populations, and these different populations co-occur geographically in the Indo-Pacific region, while A. marmorata and A. bengalensis bengalensis showed a panmictic-population structure in this region. The populations of A. bicolor bicolor were also found to have lower genetic variability than the populations of A. marmorata and A. bengalensis bengalensis. This study is the first to explore the population genetic structure of A. bengalensis bengalensis. The present results also suggest plausible dispersion and migration of these tropical species into their continental habitats.

Size-dependent changes in habitat use of Japanese eel Anguilla japonica during the river life stage

2020 ◽  
Vol 103 (3) ◽  
pp. 269-281 ◽  
Author(s):  
Manabu Kume ◽  
Yuki Terashima ◽  
Fumika Kawai ◽  
Alisa Kutzer ◽  
Toshihiro Wada ◽  
...  
Keyword(s):  
Habitat Use ◽  
Life Stage ◽  
Anguilla Japonica ◽  
Japanese Eel ◽  
Size Dependent

Scats can reveal the presence and habitat use of cryptic rock-dwelling macropods

2006 ◽  
Vol 54 (5) ◽  
pp. 325 ◽  
Author(s):  
Wendy R. Telfer ◽  
Anthony D. Griffiths ◽  
David M. J. S. Bowman
Keyword(s):  
Habitat Use ◽  
Radio Telemetry ◽  
Classification Tree ◽  
Habitat Preferences ◽  
Wet Season ◽  
Survey Tool ◽  
Faecal Pellets ◽  
Tropical Environments ◽  
The Tropics ◽  
Larger Sample

The rock-dwelling macropod species of the tropics of the Northern Territory, Australia, are behaviourally elusive and difficult to observe in their rugged habitats. Hence, little is understood about their ecology. We evaluated the potential of using scats (faecal pellets) as a survey tool for this faunal assemblage by: (1) developing a key to the scats of the species; (2) examining the rates of loss and decomposition of short-eared rock-wallaby (Petrogale brachyotis) scats in these tropical environments; and (3) comparing the distribution of scats of P. brachyotis with the species’ use of space and habitats as determined with radio-telemetry. Classification tree modelling discriminated the scats of the seven macropod species, primarily on the basis of width. The reliability of identification was greatly improved with larger sample sizes and inclusion of a habitat parameter. Rates of scat loss and decay were variable and the greatest losses occurred in the wet season, particularly on sandy soils. Scat censuses underestimated the total area used by P. brachyotis but the distribution of scats showed the same broad pattern of habitat use found by radio-telemetry. We conclude that scats can accurately indicate the presence and habitat preferences of rock-dwelling macropod species.

Differential habitat use by a local population of subadult common dunnarts, Sminthopsis murina, following wildfire in coastal wet heath, New South Wales, Australia

2005 ◽  
Vol 32 (7) ◽  
pp. 617 ◽  
Author(s):  
Vaughan Monamy ◽  
Barry J. Fox
Keyword(s):  
Soil Moisture ◽  
Habitat Use ◽  
New South ◽  
Habitat Preferences ◽  
Local Population ◽  
New South Wales ◽  
High Soil Moisture ◽  
South Wales ◽  
Unusual Occurrence ◽  
Habitat Fidelity

Little has been published about Sminthopsis murina, a small insectivorous marsupial encountered infrequently during trapping studies. Individuals favour vegetation associations found in recently burnt heathlands and forests; however, individuals rarely remain in such areas long enough for repeated capture. We report an unusual occurrence of habitat fidelity by a dense population of subadult S. murina in coastal wet heath, New South Wales, Australia. Individuals were captured repeatedly in the first 16 months following wildfire (30 subadults trapped 154 times: recapture rate = 80%). Densities peaked 10 months after fire at 3.75 individuals ha–1. More males than females were captured (23 males, 7 females). Habitat analyses revealed differential use of regenerating coastal wet heathland by S. murina. Significantly more captures were made in areas of high soil moisture in the first six months following fire. Captures then decreased in these areas but increased where soil moisture had been lower and where vegetation had been growing more slowly. Beyond the 1995/96 breeding season, regenerating vegetation became increasingly dense and less patchy and captures of S. murina ultimately declined to zero. This paper records a rare opportunity to examine habitat preferences of a single cohort of subadult S. murina. Habitat use may have been determined by the presence of a narrow range of vegetation structure.

Ecology of the rufous hare-wallaby, Lagorchestes hirsutus Gould (Marsupialia : Macropodidae) in the Tanami Desert, Northern Territory.I Patterns of habitat use.

1993 ◽  
Vol 20 (4) ◽  
pp. 457 ◽  
Author(s):  
G Lundie-Jenkins
Keyword(s):  
Habitat Use ◽  
Environmental Parameters ◽  
Home Ranges ◽  
Faecal Pellets ◽  
Habitat Features ◽  
Food Diversity ◽  
Local Contraction ◽  
Feeding Area ◽  
Controlled Burns ◽  
Insight Into

A 2-year study was conducted to investigate two aspects of the local distribution of the rufous harewallaby, Lagorchestes hirsutus, in a region of the Tanami Desert. These were: (a) patterns of habitat use in response to changing environmental conditions and (b) environmental parameters influencing 'local' choice of habitat. Counts of faecal pellets and tracks were used to obtain indices of hare-wallaby activity within occupied sites and to gain an insight into the movements by individuals. Local choice of habitat was analysed by assessment of numerous habitat features at occupied and unoccupied sites in the region. Previous surveys over the greater part of the study area provide evidence of a significant local decline and local contraction of range by L. hirsutus during recent times. Hare-wallabies showed seasonal trends in the relative use of different vegetation systems in response to the relative availability of food items within each habitat. The home ranges of hare-wallabies consisted of two distinct areas of activity: a large sparsely used area within the dense Triodia pungens vegetation and a small concentrated feeding area within the neighbouring caliche system. Hare-wallabies were dependent upon a specialised form of spinifex habitat. Patchiness, hummock size, food diversity and the degree of floral senescence affected suitability for hare-wallabies. Within the Tanami Desert site, suitable combinations of these characters were associated with tight mosaics of different regenerative stages after fire. Fire is therefore clearly implicated as an important force in creating a greater diversity of feeding and sheltering habitats for the hare-wallabies in the otherwise uniform spinifex sandplains. There is an obvious role for the application of controlled burns as a means of managing habitats to favour L. hirsutus in the Tanami Desert.

scholarly journals Hellbender Salamanders (Cryptobranchus alleganiensis) Exhibit an Ontogenetic Shift in Microhabitat Use in a Blue Ridge Physiographic Region Stream

2017 ◽  
Author(s):  
K. A. Hecht ◽  
M. J. Freake ◽  
M. A. Nickerson ◽  
P. Colclough
Keyword(s):  
Habitat Use ◽  
Life Stage ◽  
Quality Parameters ◽  
Microhabitat Use ◽  
Life Stages ◽  
Ontogenetic Shift ◽  
Ontogenetic Shifts ◽  
Gravel Beds ◽  
Cryptobranchus Alleganiensis ◽  
Significant Difference

ABSTRACTOrganisms that experience large changes in body size during the life span often exhibit differences in resource use among life stages. Ontogenetic shifts in habitat use reduce intraspecific competition and predation and are common in lotic organisms. Although information on the immature life stages of the Hellbender (Cryptobranchus alleganiensis) is limited, this aquatic salamander exhibits ontogenetic shifts in habitat use in some streams, with adults sheltering under large rocks and larvae utilizing interstitial spaces of gravel beds. Due to the geomorphology of Little River, Tennessee, however, limited interstitial spaces within the gravel are filled with sand. Therefore, we quantified microhabitat parameters for three life stages of Hellbenders (larvae, sub-adult, adult) to determine if an ontogenetic shift in microhabitat occurred in Little River. We found no significant differences in stream substrate at capture sites among the stages, but there was a positive correlation between rock shelters underlain with very coarse gravel and overall Hellbender occupancy. Although we found no difference in water quality parameters and streambed particle size among the stage classes at the sites of capture, there was a significant difference in the average shelter size among all stages, with larvae utilizing the smallest shelters. Based on these results, future Hellbender research and conservation efforts should consider differences in life stage habitat use as well as specific stream particle classes.

scholarly journals Aspects of the Biology of Juvenile Freshwater Eels (Anguillidae) in New Zealand

2021 ◽  
Author(s):  
◽  
Donald John Jellyman
Keyword(s):  
New Zealand ◽  
Fresh Water ◽  
Habitat Preferences ◽  
Spring Tide ◽  
Age Groups ◽  
Upstream Migration ◽  
Coastal Lake ◽  
Anguilla Australis ◽  
Glass Eels ◽  
Freshwater Eels

<p>The early freshwater life of the two species of New Zealand freshwater eels, Anguilla australis schmidtii Phillipps and A. dieffenbachii Gray was studied involving an examination of 8131 glass-eels, 5275 migratory elvers, and 4291 resident eels of less than 26 cm. Most eels were collected from the Makara Stream, Wellington by set-net, hand-net and electric fishing. These extensive samples together with subsidiary collections from elsewhere in New Zealand show that glass-eels of both species arrive in fresh-water from July to December. Their otoliths indicate a marine larval life of about 18 months but it is not possible as yet to locate the precise oceanic spawning areas. Migratory movements of glass-eels are in two phases: an invasion of fresh-water from the sea and an upstream migration. The former occurs only at night with a periodicity corresponding to the daily ebb-flood tidal rhythms. There is a seasonal reversal in this response which is attributable to the onset of the behavioural transition taking place prior to the second migratory phase. Increased pigmentation and changes in response to light, flowing fresh-water and schooling tendencies characterise this latter migration which occurs primarily at spring tide periods. Such juvenile eels show specific habitat preferences and a high degree of olfactory differentiation of water types. This behaviour, together with pigment development and physical tolerances, was studied in the laboratory. Measurements of invading glass-eels show that mean length, weight and condition all decline throughout the season of arrival but mean vertebral numbers remain constant. An upstream migration of small eels (elvers) occurs each summer and is readily observed at many hydro-electric stations. These migrations, comprising eels of mixed sizes and age groups, penetrate progressively further upstream each year. In both species, scales begin formation at body lengths of 16.5-20 cm. All features of scale formation, including the number of scale rings, are related to length with relative differences in rate of development occurring between the species. In contrast to scale rings, otolith rings are annual in formation and become visible after grinding or burning the otolith. Growth rates established for 273 eels to 29 cm in length from the Makara Stream, Wellington, are slow, with mean annual increments of 2.2 and 2.1 cm respectively for shortfins and longfins. In contrast, shortfins from a coastal lake near Wellington reach 26 cm in their third year of freshwater life. Length-weight relationships for small eels are given together with mean monthly condition factors. Growth studies on elvers held in a multiple tank unit in which temperature, density, and amount and frequency of feeding could be controlled, show that young eels grow more slowly than normal under such conditions. However, growth appears optimum at 20 degrees C with a feeding rate of 5-7% body weight per day. Feeding efficiency decreases with higher temperatures. At both glass-eel and elver stages, shortfins adapt and survive better under artificial conditions.</p>

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