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The nearshore fish assemblage structures and their seasonal changes were compared between two habitats (estuarine and surf zones) in three climatic regions (Tropical, 7°S; Transition, 23°S; and Warm Temperate, 32°S) encompassing ∼3200 km in the Brazilian coast. Regional patterns of species richness and taxonomic distinctiveness of the fish community were also described. We expected the highest richness and lowest seasonal variation in the assemblage's structure in the Tropical region and the opposite pattern in the Warm Temperate region. The assemblage structures differed significantly among regions and habitats. In the estuarine habitats, species richness and taxonomic distinctiveness (AvTD) were highest in the Tropical (84 species, AvTD = 92.3) and lowest in the Temperate (31 species, AvTD = 73.9) region. However, in the surf zone the highest species richness and taxonomic distinctiveness were found in the Transition region (49 species, AvTD = 78.5) and the lowest in the Warm Temperate region (19 species, AvTD = 51.9). The two habitats (estuarine and surf zone) differed consistently in the three regions. No seasonal change was found in the structure for the fish assemblage in the Tropical and Transition regions. However, the assemblage structure differed significantly between the spring and summer and between the spring and autumn in the Warm Temperate region. The most significant predictors of the fish community structure were salinity for the Tropical region, temperature and salinity for the Transition region, and transparency and temperature for the Warm Temperate region. The marine fish communities presented low levels of species redundancy in the Warm Temperate region with few species fulfilling key functional roles. The data provided here are references against which to detect future ecological changes at the regional-scale patterns for the Brazilian nearshore fish community and it is important to better inform fisheries management and coastal conservation planning. [ABSTRACT FROM AUTHOR]

We assessed inter-annual changes in fish assemblages of a tropical bay which experienced a heavily industrialized process in the last decades. A highly significant difference in community structure among the bay zones, and a decrease in fish richness and abundance over time were found. Changes in fish richness and abundance between the two first (1987–1988 and 1993–1995) and the two latter time periods (1998–2001 and 2012–2013) were sharpest in the inner bay zone, the most impacted bay area, and in the middle zone, whereas the outer zone remained comparatively stable over time. These changes coincided with increased metal pollution (mainly, Zn and Cd) in the bay and with the enlargement of the Sepetiba Port. Spatial changes in the fish community structure among the bay zones were related to differences in salinity, transparency and depth with this latter variable acting as a buffer stabilizing temporal community changes. [ABSTRACT FROM AUTHOR]

Diel fluctuations in nearshore fish communities were studied at a sandy beach in south-eastern Brazil. A total of 192 samples were performed by beach seines, during 3-hour intervals throughout 48-hour periods, between spring 2005 and winter 2006. Mean biomass and number of species were significantly higher at night, while number of individuals did not differ between day and night. Major disruptions in the fish community occurred during the winter when the assemblages underwent restructuring. Harengula clupeola, Sardinella janeiro, Anchoa lyoleps and Umbrina coroides were the predominant species at night, while Atherinella brasiliensis, Pomatomus saltatrix and Trachinotus carolinus peaked during the day, although significant diel changes in community structure were recorded only in the summer. Biological interactions, behavioural variations and local constraints might explain diel differences in the fish distribution. This study confirms that changes in diel activity in juvenile fish species can differ in similar areas, even for a given species, and the causes of these changes needs to be investigated. [ABSTRACT FROM PUBLISHER]

Short-term dynamics in juvenile fish assemblage structure were studied to test whether the most abundant species show temporal segregation, in order to assess whether selected environmental variables could predict species groupings, and to examine the stability of sunset–day–sunrise–night differences. Samplings were collected at 3-h intervals over 48 h on a seasonal basis between spring 2005 and winter 2006. Fish species richness and abundance were higher in spring, and the lowest values occurred in winter. Harengula clupeola occurred mainly in spring, whereas Atherinella brasiliensis peaked in summer and autumn. On the other hand, Trachinotus carolinus, Umbrina coroides and Mugil liza were abundant in winter. Although temperature, salinity and dissolved oxygen were not found to have a strong effect on the abundance patterns of most species, they did appear to have a significant influence on assemblage groupings, according to canonical correspondence analysis and Spearman rank correlation. There is no consistency of diel usage patterns by a given species across seasons. The relative abundance differed between the time of day, which differed among the seasons; this further complicates an understanding of the dynamics of an assemblage. Studies of diel changes that pooled the sampling period as day or night can miss important changes that occur in a short time scale, such as a 3-h period. [ABSTRACT FROM AUTHOR]

Abstract: This study analyzed the factors structuring demersal fish community in a tropical bay in southeastern Brazil. The results were used to quantify the partitioning of ecological variation among the environmental, spatial and temporal components molding the fish community. Three bay zones (inner, middle and outer) were defined according to depth and salinity gradient. Monthly samplings were conducted by bottom trawl tows during daylight hours, between October 1998 and September 1999. In each zone, three replicate samples were taken. Ninety-three fish species from 73 genera and 37 families were recorded in the 108 samples. Two demersal fish assemblages were evidenced, one in the inner and the other in the outer zone. These assemblages were characterized by changes in species composition and relative abundance. Depth, followed by transparency and salinity, influenced spatial pattern of fish assemblages. The largest part of the explained variation occurred as a result of the spatial structure of environmental variables, which means that both species and environmental variables presented similar spatial structure. The spatial effect, not the seasonal, explained the highest part of species variations. The amount of unexplained variation was relatively high (76%), even assuming that part of it is due to nondeterministic fluctuation, which could be due to local effects of unmeasured (biotic and abiotic) controlling variables. Knowing the relative importance of these factors can be of decisive importance when applying casual hypotheses in the framework of some precise ecological theory and should facilitate management, planning, and usage of bay resources. [Copyright &y& Elsevier]

Abstract: Co-occurrence of demersal fishes was assessed in a tropical bay in southeastern Brazil along an environmental gradient (inner, middle, and outer zones), defined according to depth and salinity. The aim was to test whether fish species are distributed randomly and independently of one another in accordance with a null model. The unconstrained null hypothesis for occurrence of a given species by chance in relation to other species was accepted for each zone separately, and rejected for the bay as a whole, for the full year and for each season separately, except summer. Findings of the environmentally constrained null models, which predict species presence or absence as a function of environmental conditions, were not significant, suggesting that the environmental variables we chose are not key factors for these species and that biotic interactions between species are not strong when species–environment relationships are considered. The partition of available resources inside each zone and fish movements along the three zones during summer may have contributed to higher fish species co-occurrence. Habitat segregation in the bay during the remaining seasons could explain the pattern of reduced co-occurrence, indicating the presence of two fish assemblages associated with different environmental characteristics. [Copyright &y& Elsevier]

Local Ecological Knowledge (LEK) is based on the knowledge that a community has about the organisms that occur in the place where people has lived for generations and can be useful to complement biological knowledge. The LEK of artisanal fishermen in the Sepetiba Bay (coast of the State of Rio de Janeiro) on the reproduction, migration and interactions (feeding and parasitism) of the mullet Mugil liza was analyzed. Semi-structured interviews were conducted with 40 informants (24–79 years old), from November 2017 to January 2019, considering the emic (fisherman's perception) and ethic (scientist's perception) aspects. Fishermen's information coincided with the literature for aspects of the species' biology, such as reproductive period, feeding patterns and parasitic relationships. However, new patterns have been described by the fishermen. These new patterns pointed to a probable reduction in the fish maximum body size and first maturation size. In addition, LEK also points to an additional period of reproduction in the summer, and the presence of north and east winds favoring the appearance of individuals in the bay. The summer spawning, already reported in other areas, was not foreseen in the biological literature for the Sepetiba Bay, and the LEK associated this spawning season to a possible resident population that stay most of the time under structures formed by wharfs of mega-enterprises in the area. Also, the mullet could be forming different metapopulations on the Southeast-South coast of Brazil with part of these populations entering into the Sepetiba Bay. These points raised by LEK need to be tested by biological studies, which could help to a rational management and conservation of this important fishery resource in the southeastern and southern Brazil. [Display omitted] • The LEK of artisanal fishermen in the Sepetiba Bay, State of Rio de Janeiro, Brazil, were assessed for the mullet Mugil liza. • Although fishermen's information coincided with several aspects of the literature, new patterns were described. • According to LEK, there is an additional resident population and an additional spawning season in the summer. • These new information need to be tested by biological studies, and could be helpful to conservation policies. [ABSTRACT FROM AUTHOR]

Abstract: Fish communities and habitat structures were evaluated by underwater visual censuses a rocky location impacted by thermal discharge (I) and at two control locations, one in a Sargassum bed (C1) and the other in a rocky shore with higher structural complexity (C2). Habitat indicators and fish communities exhibited significant differences between the impacted and control locations, with the impacted one showing a significant decrease in fish species richness and diversity, as well as a decrease in benthic cover. At the I location, only 13 fish species were described, and the average water temperature was 32±0.4°C, compared with 44 species at C1 (25.9±0.3°C) and 33 species at C2 (24.6±0.2°C). Significant differences in fish communities among locations were found by ANOSIM with Eucinostomus argenteus, Mugil sp. and Haemulon steindachneri typical of location I, while Abudefduf saxatilis, Stegastes fuscus and Malacoctenus delalandi were typical of the control locations. Our study shows that thermal pollution alters benthic cover and influences fish assemblages by altering composition and decreasing richness. [Copyright &y& Elsevier]

The study of aquatic environments is sometimes difficult to do with normal sampling methods that use gears. Insectivorous fishes represent good users of these ecosystems and analyzing the aquatic organisms present in fish stomachs, is an alternative way to determine resource abundance and utilization. In this paper, the potential of Trachelyopterus striatulus as an insect sampler was examined through dietary analyses of 383 individuals caught between April 1999 and March 2000 in Lajes Reservoir, a 30 km2 oligotrophic impoundment in Southeast Brazil. We estimated frequency of occurrence and Schoener's index of similarity. Diet changes among seasons and reservoir zones were addressed with DCA and ANOVA analyses. Its diet was 92.1% insects (ten orders and nine families). Hymenoptera (57.90%), Odonata (39.76%), Trichoptera (27.41%), Ephemeroptera (26.25%) and Coleoptera (28.96%) were the most common groups. Highest insect occurrence and richness were recorded in autumn-summer, a period of greater rainfall and insect activity. Formicidae, the dominant prey item in all seasons, appeared to be especially important in spring, a season marked by shortness of food resources. Trichoptera and Ephemeroptera were the most consumed prey items in the other seasons. Highest insect occurrence and richness were recorded in the middle and upper reservoir zones, respectively. Trichoptera and Ephemeroptera prevailed in the upper zone, where small pristine rivers and tributaries are abundant, whereas Formicidae and Belostomatidae predominated in the lower and middle zones. Because of its abundance in many freshwater ecosystems of Brazil, the ubiquity of insects in its digestive tract and the low level of prey degradation, T. striatulus has potential as an insect sampler of Neotropical reservoirs. However, conventional sampling in Lajes Reservoir is necessary to compare the effectiveness of T. striatulus with other insect sampling methods. Rev. Biol. Trop. 57 (4): 1081-1091. Epub 2009 December 01. [ABSTRACT FROM AUTHOR]