Community structure and niche breadth of some fish in Pangelang Protected Lake, Kapuas Hulu District

Ecologically, weather changes cause local deviations from regional patterns in waters. So that there will be changes in fish types and food habits.The purpose of this study was to determine changes in fish community structure, food preferences, and area of niches for each type of fish in Pangelang Protected Lake. The research was conducted using a survey method in October 2016 (low tide), June 2018 (transition) and September (flood) 2018. The results obtained: 1. Fish communities in Lake Pangelang obtained a total of 12 families, 30 genera, and 37 species. In the low tide season, there are 21 species of fish caught, 17 species of transition season and 16 types of flood during low tide. 2. In the low tide season, the fish community in Pangelang Lake is dominated by detritivorous fish. In the transitional season, the fish community in Pangelang Lake experiences changes with an increase in the union of phytoplanktivore and insectivore fish. During the flood season, the fish communities in Lake Pangelang underwent a change again where the union of herbivores that used plants increased.

Scraping and grazing herbivorous/detritivorous fish display opposite feeding behaviours under different protection regulations

Background:Functional groups, especially herbivorous fishes, are important for mediating benthic community structure on coral reefs. Herbivorous and detritivorous fish display complex feeding behaviour, and research into schooling feeding behaviour and feeding rates, and how these change with environmental and social behavioural variables is lacking. Such knowledge is imperative to infer how herbivory/detritivory will change, in light of changing resources and communities, specifically whether reefs can recover from disturbance. Differences in abundance, feeding rate, body length, diet preferences, and schooling size of three major functional groups, scrapers, grazers and browsers were examined across reef habitats under different fishing regulations, such as no-take restricted zones and open-fishing general use zones. Although marine protected areas have been implemented to conserve reef fish species; further precise management based on ecological behaviour of functional groups is necessary.Results:Scrapers and grazers which were mostly parrotfishes and surgeonfishes were more abundant on reef flats and also displayed the highest feeding rates on reef flats. Although scrapers mainly resided inside the restricted zone, more grazers were found in the general use zone where macroalgae abundance was highest, indicating a higher availability of nutritional resources. Browsers, mostly rabbitfishes, were seldom observed and patchily gathered on the reef flat and slope in both zones. Thus, fishing protection did not appear to benefit grazers and browsers, whereas scrapers gathered on shallow reef flats in the protection zone. Lastly, scraper and grazer feeding rates increased from an individual to paired feeding, and increased with body size, these factors led to variations in feeding behaviours on different habitats under different protection regulations.Conclusions:Fishing protection benefits scrapers which subsequently appears to be resulting in a reduction in algal coverage, and variation in feeding rates was largely related to school sizes. The density of these functionally important grazers was influenced more by changes to benthic composition than protection status. The opposite feeding behaviours of two herbivorous/detritivorous functional groups indicates not only protection status, but fishing gear and size limit regulations are needed to help maintain fisheries and diversity on coral reefs in Taiwan.

Feeding strategies differentiate four detritivorous curimatids in the Amazon

Differences in food intake and morphological attributes may facilitate the coexistence of detritivorous fish. The present study investigated the possible differences in the feeding strategies of four species of curimatids that inhabit the floodplain of the central Amazon. For this, we determined the diet, daily food cycle, and whether characteristics of the intestine were related to the length of the fish and the amount of detritus consumed. The detritivory was confirmed, and we observed a difference in the foraging time between species. We found differences in the length and weight of the intestine and the relationship of these variables with the length of the fish and the amount of detritus consumed. Our study suggests that despite belonging to the same family and food group, curimatids have characteristics that allow them to consume the detritus in different ways.

Divergence in energy sources for Prochilodus lineatus (Characiformes: Prochilodontidae) in Neotropical floodplains

ABSTRACT The stable carbon isotopic variability and the contributions of autochthonous (sediment microbial biomass, phytoplankton, and periphyton) and allochthonous (soil microbial biomass) sources available to the detritivorous fish Prochilodus lineatus were investigated in three environments of the floodplain of the Upper Paraná River. The isotopic composition of carbon sources and fish varied significantly among the studied environments. The autochthonous resources, represented by the phytoplankton, were the most assimilated by the species, followed by periphyton and sediment microbial biomass. The species used the sources differently in each environment. This study suggests that the inherent characteristics of this area, as well as the size of the watershed, the dry season, anthropogenic actions, and phytoplankton productivity, favor the use of autochthonous resources by the species studied. Therefore, studies in the floodplain should employ an eco-hydrological approach that quantifies the magnitude of energy subsidies, as well as an access route to consumers, knowledge about the selectivity of detritivorous species and the effects of different land uses.