Diverse Habitat Use Research Articles

Connectivity between lentic and lotic freshwater habitats identified as a conservation priority for coho salmon

Abstract Juvenile Pacific salmon exhibit diverse habitat use and migration strategies to navigate high environmental variability and predation risk during freshwater residency. Increasingly, urbanization and climate‐driven hydrological alterations are affecting the availability and quality of aquatic habitats in salmon catchments. Thus, conservation of freshwater habitat integrity has emerged as an important challenge in supporting salmon life‐history diversity as a buffer against continuing ecosystem changes. To inform catchment management for salmon, information on the distribution and movement dynamics of juvenile fish throughout the annual seasonal cycle is needed. A number of studies have assessed the ecology of juvenile coho salmon (Oncorhynchus kisutch) during summer and autumn seasons; catchment use by this species throughout the annual cycle is less well characterized, particularly in high‐latitude systems. Here, n = 3,792 tagged juvenile coho salmon were tracked throughout two complete annual cycles to assess basin‐wide distribution and movement behaviour of this species in a subarctic, ice‐bearing catchment. Juvenile coho salmon in the Big Lake basin, Alaska, exhibited multiple habitat use and movement strategies across seasons; however, summer rearing in lotic mainstem environments followed by migration to lentic overwinter habitats was identified as a prominent behaviour, with two‐thirds of tracked fish migrating en masse to concentrate in a small subset of upper catchment lakes for the winter. In contrast, the most significant tributary overwintering site (8% of tracked fish) occurred below a culvert and dam, blocking juvenile fish passage to a headwater lake, indicating that these fish may have been restricted from reaching preferred lentic overwinter habitats. These findings emphasize the importance of maintaining aquatic connectivity to lentic habitats as a conservation priority for coho salmon during freshwater residency.

Diverse habitat use during two life stages of the critically endangered Bahama Oriole (Icterus northropi): community structure, foraging, and social interactions.

Our ability to prevent extinction in declining populations often depends on effective management of habitats that are disturbed through wildfire, logging, agriculture, or development. In these disturbed landscapes, the juxtaposition of multiple habitat types can be especially important to fledglings and young birds, which may leave breeding grounds in human-altered habitat for different habitats nearby that provide increased foraging opportunities, reduced competition, and higher protection from predators. In this study, we evaluated the importance of three habitat types to two life stages of the critically endangered Bahama Oriole (Icterus northropi), a synanthropic songbird endemic to Andros, The Bahamas. First, we determined the avian species composition and relative abundance of I. northropi among three major vegetation types on Andros: Caribbean pine (Pinus caribaea) forest, coppice (broadleaf dry forest), and anthropogenic areas, dominated by nonnative vegetation (farmland and developed land). We then compared the foraging strategies and social interactions of two age classes of adult Bahama Orioles in relation to differential habitat use. Bird surveys late in the Bahama Oriole’s breeding season indicated the number of avian species and Bahama Oriole density were highest in coppice. Some bird species occurring in the coppice and pine forest were never observed in agricultural or residential areas, and may be at risk if human disturbance of pine forest and coppice increases, as is occurring at a rapid pace on Andros. During the breeding season, second-year (SY) adult Bahama Orioles foraged in all vegetation types, whereas after-second-year (ASY) adults were observed foraging only in anthropogenic areas, where the species nested largely in introduced coconut palms (Cocos nucifera). Additionally, SY adults foraging in anthropogenic areas were often observed with an ASY adult, suggesting divergent habitat use for younger, unpaired birds. Other aspects of foraging (vegetation features, food-gleaning behavior, and food items) were similar for the two age classes. Older Bahama Orioles exhibited relatively higher rates of social interactions (intraspecific and interspecific pooled) in anthropogenic areas, and won more interaction outcomes compared to younger adults. Our findings concur with those of other studies indicating dry broadleaf forest is vitally important to migrating, wintering, and resident birds, including the critically endangered Bahama Oriole, which appears to depend heavily on this vegetation type during certain life stages.

Fatty acid composition indicating diverse habitat use in coral reef fishes in the Malaysian South China Sea.

BackgroundIn order to understand feeding ecology and habitat use of coral reef fish, fatty acid composition was examined in five coral reef fishes, Thalassoma lunare, Lutjanus lutjanus, Abudefduf bengalensis, Scarus rivulatus and Scolopsis affinis collected in the Bidong Island of Malaysian South China Sea.ResultsProportions of saturated fatty acids (SAFA) ranged 57.2% 74.2%, with the highest proportions in fatty acids, the second highest was monounsaturated fatty acids (MUFA) ranged from 21.4% to 39.0% and the proportion of polyunsaturated fatty acids (PUFA) was the lowest ranged from 2.8% to 14.1%. Each fatty acid composition differed among fishes, suggesting diverse feeding ecology, habitat use and migration during the fishes’ life history in the coral reef habitats.ConclusionsDiets of the coral fish species might vary among species in spite of that each species are living sympatrically. Differences in fatty acid profiles might not just be considered with respect to the diets, but might be based on the habitat and migration.

Variable habitat use by Japanese eel affects dissemination of swimbladder parasite Anguillicola crassus

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 5:143-147 (2009) - DOI: https://doi.org/10.3354/ab00143 Variable habitat use by Japanese eel affects dissemination of swimbladder parasite Anguillicola crassus Yu San Han1,2,*, Ya Ting Chang2, Wann Nian Tzeng1,2 1Department of Life Science, and 2Institute of Fisheries Sciences, Science College of Life Science, National Taiwan University, Taipei 106, Taiwan *Email: yshan@ntu.edu.tw ABSTRACT: Freshwater habitat use by yellow-stage eels is facultative. Survival, infestation rates, and prevalence of the swimbladder parasite Anguillicola crassus (Nematoda) in European eel is higher in freshwater than in brackish water or seawater. This suggests that infestation patterns vary among habitats with different salinity. To evaluate whether Japanese eel Anguilla japonica populations with different habitat use behavior have different parasite dispersion modes, we examined by electron probe microanalyzer the otolith strontium:calcium (Sr:Ca) ratios of 166 Japanese eels collected from the Kaoping River, southwestern Taiwan, in 2006 and 2007. According to the mean and SD of otolith Sr:Ca ratios, we differentiated between 3 types of habitat use in eels: freshwater, low-migratory (Type 1), brackish water, low-migratory (Type 2), and high-migratory (Type 3). The mean prevalence of A. crassus was lowest in Type 2, intermediate in Type 1, and highest in Type 3, but there were no significant differences. Mean intensity of A. crassus at the larval stage (but not adult stage) was significantly higher for Type 1 than for the other 2 types. Our results suggest that diverse habitat use by Japanese eels implies behavioral plasticity to make use of different ecological niches. High-migratory Type 3 eels, which dominate the population, may serve as vectors disseminating A. crassus among different habitats. KEY WORDS: Otolith · Strontium:calcium (Sr:Ca) ratio · Anguillicola crassus · Infestation · Dissemination · Nematoda Full text in pdf format PreviousNextCite this article as: Han YS, Chang YT, Tzeng WN, (2009) Variable habitat use by Japanese eel affects dissemination of swimbladder parasite Anguillicola crassus. Aquat Biol 5:143-147. https://doi.org/10.3354/ab00143 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 5, No. 2. Online publication date: March 17, 2009 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2009 Inter-Research.

Estimation of roe deerCapreolus capreolus and mouflonOvis aries densities, abundance and habitat use in a mountainous Mediterranean area

The abundance, density, and habitat use of roe deerCapreolus capreolus (Linnaeus, 1758) and mouflonOvis aries Linnaeus, 1758 were studied in a confined Mediterranean area in Greece with a dung survey based on the faecal accumulation rate (FAR) technique. Estimated density was modelled with generalized additive models using altitude, habitat type, and slope as potential covariates. Model selection among the set of candidate models was conducted based on their generalized cross-validation score. Roe deer had an estimated mean density of 13.9 ind./km2 and the best model included slope and habitat type as covariates. The mean density of mouflon in the study area was 22.1 ind./km2 and the best model used altitude and habitat type as covariates. For both species, the highest densities were encountered in abandoned cultivations and glades, followed by conifer forests, while the lowest densities were observed in maquis. However, use of open habitats by mouflon was much greater than it was for roe deer. The strong preference of mouflon (a grazer species) for open habitats that were abundant with grasses probably reflected food availability and contrasted with the more diverse habitat use by roe deer (a selective browser).