جستجوی مقالات مرتبط با کلیدواژه "temporal variation" در نشریات گروه "زیست شناسی"

This study aimed to assess the temporal variation in fish assemblage in Chabahar Bay mangrove habitat. Baited Remote Underwater Video (BRUV) sampling method was applied to record the fish presence. Fishes were sampled monthly from June 2017 to April 2018 at daylight time (9:00 to 14:00) during high tide. Water temperature, turbidity, and salinity were recorded at the time of sampling. During the study, a total of 17 species belonging to 12 families were identified. Ambassis gymnocephalus was found as the dominant fish throughout the year except in November and December. The most abundant fish fauna in numbers was characterized by the following five species: Ambassis gymnocephalus (53.38%), Sardinella sp. (17.13%), Terapon jarbua (4.79%), Rhabdosargus sarba (3.25%) and Acanthopagrus berda (2.9%). ANOSIM showed that significant differences in the assemblage structure occurred among months (R=0.613, P< 0.001), and the CLUSTER analysis, together with the SIMPROF test showed that December is significantly different in term of fish assemblage. Canonical Correspondence Analysis (CCA) on species-environment correlations revealed that temperature and turbidity were the main parameters influencing fish occurrence in the mangrove habitat of Chabahar Bay. The overall diversity (Shannon–Wiener, Simpson’s Index of Diversity, and Pielou’s evenness), as well as functional diversity indexes (FRic and FDis), was higher in autumn and spring pointing out that the diversity is higher when the temperature had the closest value to averaged value

Underwater Visual Census (UVC) and Baited Remote Underwater Video (BRUV) are broadly used methods to study fish assemblages in marine and estuarine environments. This study compared the results of BRUV and UVC methods for assessing seasonal trends in coral reef fish assemblages in a marginal reef in the northern Persian Gulf. In doing so, seasonal surveys of coral reef fishes were done using BRUV and UVC methods. Comparison of assemblage metrics driven from each method indicated that both methods may reveal similar patterns of seasonal changes in fish and trophic group assemblages while there may be between-method differences in species richness, total abundance, and trophic group abundances. The observed differences may be related to the longer sampling times of BRUV.

Gastropod assemblages were investigated along intertidal rocky shore in the Qeshm Island in the northern Persian Gulf. Monthly sampling was undertaken from May 2007 to April 2008. Environmental factors were also measured in each site. A total of 28 gastropod taxa belonging to 15 families were identified and Cerithiidae was the most abundant family and Cerithium caeruleum was the most abundant species (34.77%). Muricidae with 5 species were the most diverse group followed by Cerithiidae and Cypraeidae each with 4 species. Kruskal-Wallis test yielded no significant differences in gastropod assemblages among months and also different seasons (P>0.05). The analysis of SIMPER showed that spring and autumn had the most dissimilarity among seasons and Clypeomorus bifasciatus was the species of gastropods contributing most to the dissimilarities among seasons (37.54%). December showed the highest value of Shanon-Wiener (2.15) and Simpson (0.85) indices. Lack of significant temporal variation in gastropod assemblages during sampling months suggested that intensity of sampling in future studies could be reduced to seasonal intervals in similar environmental conditions.Where intertidal surveys are restricted by time,and resources such as, personnel and finance.