Evidence Of Habitat Partitioning Research Articles

Population dynamics of Farfantepenaeus subtilis (Pérez-Farfante, 1967) and Litopenaeus schmitti (Burkenroad, 1936) (Decapoda: Penaeidae) and evidence of habitat partitioning in the northeast of Brazil

The population structure, sex ratio, size at the onset of sexual maturity, growth rates, and longevity of Farfantepenaeus subtilis and Litopenaeus schmitti were studied in the State of Sergipe, Brazil. The distribution pattern of juveniles and reproductive females was compared to investigate whether habitat partitioning takes place between these species. The sampling occurred monthly, from September/2013 to August/2014, in nine stations of three transects (5 m, 15 m, and 30 m deep) using a shrimp fishing boat. In total, 1076 F. subtilis and 499 L. schmitti individuals were captured. The sex ratio of F. subtilis was skewed toward females, while L. schmitti had a 1:1 sex ratio. Females of both species were larger than the males. The size at the onset of sexual maturity of F. subtilis females was large than that of males, while the opposite occurred in L. schmitti. The estimated growth parameters of F. subtilis males were: CL∞=33.24 mm, k = 2.30/year and longevity = 2.0 years. For the females, they were: CL∞=42.49 mm, k = 2.15/year and longevity = 2.12 years. The growth parameters of L. schmitti males were: CL∞=32.48 mm, k = 2.41/year and longevity = 1.91 years. For the females, they were: CL∞=38.78 mm, k = 2.01/year and longevity = 2.29 years. The distribution patterns of juveniles and reproductive females differed between species. F. subtilis females predominated in deeper waters. Juveniles of L. schmitti were aggregated in shallow waters (5 m), while F. subtilis aggregated at 15 m. Considering that (1) the relationship between the environmental factors and the abundance of juveniles and females was not evident, and (2) the reproductive and recruitment periods of these species are synchronized, our results suggest that habitat partitioning takes place to decrease the interspecific competition.

Seasonal Habitat Use of Slimy Sculpin and Juvenile Rainbow Trout in a Central New York Stream

Non-native Oncorhynchus mykiss (Rainbow Trout) have been shown to have negative effects on native salmonid populations. However, interspecific associations between Rainbow Trout and native non-salmonid species have received little attention. Cottus spp. (sculpin) are a native benthic species group that comprise an important component of many lentic and lotic ecosystems in North America. In this study, we examined seasonal habitat associations between juvenile Rainbow Trout and C. cognatus (Slimy Sculpin) in a stream in the Lake Ontario watershed in New York. There was evidence of habitat partitioning among the age classes examined, with overyearling Rainbow Trout and subyearling Slimy Sculpin occupying disparate habitat. The habitat use by subyearling Rainbow Trout and overyearling Slimy Sculpin was similar, which may increase the potential for competition between these age groups. Overyearling Rainbow Trout exhibited the highest degree of habitat selection, whereas subyearling Slimy Sculpin exhibited the least. Our observations are the first reported on the ecological associations of Rainbow Trout and Slimy Sculpin and may provide important information in instances where sculpin are being re-introduced.

Distribution and feeding ecology of three juvenile mojarras in a hypersaline tropical estuary in Northeastern Brazil

AbstractAlthough mojarra species usually demonstrate a wide distribution in tropical and subtropical estuaries, relatively little is known about the process influencing the spatial resource partitioning to nearshore habitats. Therefore, the aim of this study was check the existence of habitat and food partitioning among confamiliar species in a hypersaline estuary. The dietary compositions of three co‐occurring species of mojarras were determined, using samples collected with a beach seine from an inverse tropical estuary in Northeastern Brazil, during the rainy and the dry seasons of 2012. Eucinostomus argenteus and Ulaema lefroyi were abundant throughout the year, while Eugerres brasilianus was most abundant during the rainy season. Although these mojarras were found together in all areas of the estuary, there was evidence of habitat partitioning: E. argenteus and E. brasilianus were dominant in areas with submerged vegetation, while U. lefroyi was most abundant in areas with little habitat complexity and minimal shelter. All mojarras consumed, to different degrees, zooplankton, Bivalvia and Polychaeta. However, E. brasilanus also consumed a considerable amount of algae. Although the niches of the mojarra species appeared to significantly overlap, some resource partitioning patterns were apparent. While E. brasilanus was clearly different along the trophic niche, segregation of the other species was more important with respect to the spatial dimension. The different feeding strategies appear to minimize inter‐specific overlap and allow the co‐occurrence of these species in this hypersaline tropical estuary.

Responses of Primates and Other Frugivorous Vertebrates to Plant Resource Variability over Space and Time at Gunung Palung National Park

Identifying patterns of primate diversity and abundance over space and time provides a window into the ecological processes that influence species distributions and community composition. Long-term studies of primate communities across multiple habitat types at small spatial scales are rare, yet can improve our understanding of habitat and resource use. Within primate community ecology, there has been recent interest in studying primate species in the context of the broader faunal communities of which they are a part because interactions with ecologically similar but distantly related species may influence habitat use. We present the results of a 64-mo study of 10 vertebrate frugivore species with highly overlapping diets inhabiting seven distinct forest types at the Cabang Panti Research Station, West Kalimantan, Indonesia. We used survey transects and phenology plots to measure variation in vertebrate population densities (four primate, three hornbill, two squirrel, and one pig species) and fruit resources over space and time. We found little evidence of habitat partitioning or specialization. Densities of all 10 frugivore species, however, varied spatially, due largely to elevation and forest structure. Ordination analyses demonstrated that forest types differed in their structure, floristic composition, plant phenology, and frugivore communities. We also documented substantial temporal variation in orangutan densities, reflecting movements over large spatial scales. The densities of other mammalian and avian frugivores, particularly other primates, varied comparatively little over time. Our results demonstrate the importance of forest structure for determining frugivore community structure and highlight the importance of lowland forest types for the conservation of tropical frugivores.

First characterization of shark nursery habitat in the United States Virgin Islands: evidence of habitat partitioning by two shark species

Little is known of the diversity, demography, and essential fish habitat of sharks within the United States Virgin Islands (USVI) marine ecosystem. To examine species diversity and the relative abundance of elasmobranchs in this region, bottom-longline and hand-gear sampling was conducted in Fish Bay, St. John, USVI, from June 2004 to December 2005. In the 8 sampling trips during this period, 54 standardized longline sets caught 174 elasmobranchs comprising 5 species of sharks and 1 batoid. Overall catch per unit effort [ln(CPUE + 1) ± SE] was 1.83 ± 0.16 elasmobranchs 100 hooks–1 h–1. Lemon sharks Negaprion brevirostris had the highest relative abundance based on log-transformed CPUE data (0.98 ± 0.15), followed by blacktip sharks Carcharhinus limbatus (0.91 ± 0.18), southern stingrays Dasyatis americana (0.28 ± 0.08), nurse sharks Ginglymostoma cirratum (0.08 ± 0.05), blacknose sharks Carcharhinus acronotus (0.06 ± 0.04) and the Caribbean sharpnose Rhizoprionodon porosus (0.03 ± 0.03). The relative abundance of all species was significantly higher in the summer (2.6 ± 0.2) than during the winter (1.1 ± 0.2). For the blacktip (N = 89 captures of 74 individuals) and lemon (N = 66, 48 individuals) sharks, which comprised the bulk of the catch, mean fork length (± SE) was 51.9 ± 0.63 cm and 59.9 ± 1.2 cm, respectively, representing primarily neonatal and young-of-the-year life stages. The recapture rates for blacktip and lemon sharks were 21% and 29%, respectively, and nearly all recaptures occurred within the bay, indicating a high degree of site fidelity. Capture information and limited acoustic tracking provided evidence of spatial and temporal habitat partitioning by these 2 shark species within the bay. Although the CPUE of both species was highest over shallow (<1 m) seagrass substrate, lemon sharks were found and tracked exclusively on shallow, mangrove-fringed seagrass habitat, while blacktip sharks utilized a wider area of the bay. Fish Bay was determined to provide important nursery habitat for young juvenile lemon and blacktip sharks in the USVI.

Effect of Bull Trout and Brook Trout Interactions on Foraging Habitat, Feeding Behavior, and Growth

Abstract Observations of free-ranging sympatric bull trout Salvelinus confluentus and nonnative brook trout S. fontinalis in two eastern Oregon headwater streams provided little evidence of habitat partitioning. Both species held focal feeding points in similar microhabitats and fed primarily from the water column rather than from the surface or benthos. In an instream experiment, 20 enclosures were assigned one of three treatments: two bull trout, four bull trout, or a mix of two bull trout and two brook trout. In the enclosures, macroinvertebrate drift was restricted and trout densities were elevated, creating an environment of reduced food and habitat resources. Under these conditions, there was no indication of a niche shift by bull trout; feeding behavior and habitat use by bull trout did not differ depending on the presence or absence of brook trout. Brook trout in the mixed-species treatment were the most aggressive, maintained dominance in 75% of the enclosures, and exhibited significantly higher ...

Feeding mechanics in Triassic stem-group sauropterygians: the anatomy of a successful invasion of Mesozoic seas

The jaw adductor musculature in Triassic stem-group sauropterygians is reconstructed on the basis of a paradigmatic model of muscle architecture (functional equivalence of sarcomeres) and using invariant traits of the anatomy of the trigeminal jaw adductor muscles in extant reptiles. The reconstructed jaw adductor musculature predicts trophic specializations in stem-group sauropterygians. Suction feeding is a component in prey capture for some benthic feeding, as well as for some pelagic feeding taxa. The differentiation of ‘pincer’ jaws is correlated with the potential for rapid, snapping bites. There is some evidence for habitat partitioning among Triassic stem-group sauropterygians with respect to trophic specialization.

Microsite conditions and spatial pattern in a boreal bryophyte community

This study addresses the hypothesis that the spatial pattern of four bryophyte species on the forest floor of boreal woodland represents habitat partitioning, corresponding to microhabitat heterogeneity. Temperature, vapour pressure deficit, photosynthetically active radiation, incident precipitation, and litter fall were monitored at locations of pure colonies of Pleurozium schreberi, Ptilium crista-castrensis, Dicranum polysetum, and Ptilidium ciliare. From May through November 1990, the species received a mean total of 51.20 ± 1.09 cm of rain and 1.034 ± 0.639 g of litter, primarily spruce needles. They experienced temperatures as high as 40 °C, vapour pressure deficits to 7.3 kPa, and photosynthetically active radiation to 3200 μmol∙m−2∙s−1. The results do not support habitat partitioning by the species on the basis of the variables examined: all four species tolerated the full range of conditions and their combinations that occurred in the study season, and experienced the same ranges during &gt; 90% of the sampling period, with equally broad within-species variation. Although large pure colonies of P. ciliare were delimited by microsites receiving greater spruce needle litter fall and lower incident precipitation per rainfall event, smaller colonies and individual shoots were often found in mixture with other species. Overall, the spatial pattern did not correlate with microsite conditions, and we see no evidence of habitat partitioning in terms of currently occupied microsites. Key words: community structure, microclimate, Pleurozium schreberi, Ptilium crista-castrensis, Dicranum polysetum, Ptilidium ciliare.