scholarly journals Site-Level Variation in Parrotfish Grazing and Bioerosion as a Function of Species-Specific Feeding Metrics

Diversity ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 379
Author(s):  
Ines D Lange ◽  
Chris T Perry ◽  
Kyle M Morgan ◽  
Ronan Roche ◽  
Cassandra E Benkwitt ◽  
...  
Keyword(s):  
Body Size ◽  
Fish Assemblages ◽  
First Record ◽  
Limited Range ◽  
Ecosystem Functions ◽  
Central Indian Ocean ◽  
Key Species ◽  
Community Grazing ◽  
Species Specific ◽  
Chagos Archipelago

Parrotfish provide important ecological functions on coral reefs, including the provision of new settlement space through grazing and the generation of sediment through bioerosion of reef substrate. Estimating these functions at an ecosystem level depends on accurately quantifying the functional impact of individuals, yet parrotfish feeding metrics are only available for a limited range of sites, species and size classes. We quantified bite rates, proportion of bites leaving scars and scar sizes in situ for the dominant excavator (Cetoscarus ocellatus, Chlorurus strongylocephalus, Ch. sordidus) and scraper species (Scarus rubroviolaceus, S. frenatus, S. niger, S. tricolor, S. scaber, S. psittacus) in the central Indian Ocean. This includes the first record of scar frequencies and sizes for the latter three species. Bite rates varied with species and life phase and decreased with body size. The proportion of bites leaving scars and scar sizes differed among species and increased with body size. Species-level allometric relationships between body size and each of these feeding metrics were used to parameterize annual individual grazing and bioerosion rates which increase non-linearly with body size. Large individuals of C. ocellatus, Ch. strongylocephalus and S. rubroviolaceus can graze 200–400 m2 and erode >500 kg of reef substrate annually. Smaller species graze 1–100 m2 yr−1 and erode 0.2–30 kg yr−1. We used these individual functional rates to quantify community grazing and bioerosion levels at 15 sites across the Maldives and the Chagos Archipelago. Although parrotfish density was 2.6 times higher on Maldivian reefs, average grazing (3.9 ± 1.4 m2 m−2 reef yr−1) and bioerosion levels (3.1 ± 1.2 kg m−2 reef yr−1) were about 15% lower than in the Chagos Archipelago (4.5 ± 2.3 and 3.7 ± 3.0, respectively), due to the dominance of small species and individuals in the Maldives (90% <30 cm length). This demonstrates that large-bodied species and individuals contribute disproportionally to both grazing and bioerosion. Across all sites, grazing increased by 66 ± 5 m2 ha−1 and bioerosion by 109 ± 9 kg ha−1 for every kg increase in parrotfish biomass. However, for a given level of parrotfish biomass, grazing and bioerosion levels were higher on Maldivian reefs than in the Chagos Archipelago. This suggests that small-bodied fish assemblages can maintain ecosystem functions, but only if key species are present in sufficiently high numbers.

The goldrim surgeonfish (Acanthurus nigricans; Acanthuridae) from Diego Garcia, Chagos Archipelago: first record for the central Indian Ocean

Zootaxa ◽  
2008 ◽  
Vol 1850 (1) ◽  
pp. 65 ◽  
Author(s):  
MATTHEW T. CRAIG
Keyword(s):  
Indian Ocean ◽  
First Record ◽  
Outer Reef ◽  
Central Indian Ocean ◽  
The Pacific ◽  
First Occurrence ◽  
The Pacific Ocean ◽  
Tropical Reef ◽  
Chagos Archipelago ◽  
Dark Body

The goldrim surgeonfish (also known as the whitecheek surgeonfish in the aquarium trade), Acanthurus nigricans (Linnaeus), is a common and widespread member of tropical reef fish communities throughout the Pacific Ocean. It has been reported at low densities at Cocos (Keeling) and Christmas Islands in the eastern Indian Ocean. Named nigricans for its characteristically dark body color, the species usually inhabits shallow depths on the outer reef crest just below the surge zone, but has been observed as deep as 67 m (Chave and Mundy, 1994). The species feeds on filamentous algae (Randall, 2001). In this paper I report the first occurrence of Acanthurus nigricans in the central Indian Ocean (Chagos Archipelago) and provide information on its biogeography and hybridization with A. leucosternon Bennett.

scholarly journals First record of Pachycrocuta brevirostris (Gervais, 1850) from Ukraine on the background of the European occurrence of the species

2021 ◽  
Author(s):  
Adrian Marciszak ◽  
Yuriy Semenov ◽  
Piotr Portnicki ◽  
Tamara Derkach
Keyword(s):  
Body Size ◽  
First Record ◽  
The Body ◽  
Crocuta Crocuta ◽  
Early Pleistocene ◽  
Eastern Asia ◽  
South Eastern

AbstractCranial material ofPachycrocuta brevirostrisfrom the late Early Pleistocene site of Nogaisk is the first record of this species in Ukraine. This large hyena was a representative of the Tamanian faunal complex and a single specialised scavenger in these faunas. The revisited European records list ofP.brevirostrisdocumented the presence of this species in 101 sites, dated in the range of 3.5–0.4 Ma. This species first disappeared in Africa, survived in Europe until ca. 0.8–0.7 Ma, and its last, relict occurrence was known from south-eastern Asia. The main reason of extinction ofP.brevirostrisprobably was the competition withCrocuta crocuta. The cave hyena was smaller, but its teeth were proportionally larger to the body size, better adapted to crushing bones and slicing meat, and could also hunt united in larger groups.

Explaining variability in parasite aggregation levels among host samples

Parasitology ◽  
2013 ◽  
Vol 140 (4) ◽  
pp. 541-546 ◽  
Author(s):  
ROBERT POULIN
Keyword(s):  
Body Size ◽  
Strong Relationship ◽  
Host Susceptibility ◽  
Helminth Parasites ◽  
Susceptibility To Infection ◽  
Host Body ◽  
Parasite Aggregation ◽  
Using Data ◽  
Species Specific ◽  
Host Body Size

SUMMARYAggregated distributions among individual hosts are a defining feature of metazoan parasite populations. Heterogeneity among host individuals in exposure to parasites or in susceptibility to infection is thought to be the main factor generating aggregation, with properties of parasites themselves explaining some of the variability in aggregation levels observed among species. Here, using data from 410 samples of helminth parasites on fish hosts, I tested the contribution of (i) within-sample variation in host body size, taken as a proxy for variability in host susceptibility, and (ii) parasite taxon and developmental stage, to the aggregated distribution of parasites. Log-transformed variance in numbers of parasites per host was regressed against log mean number across all samples; the strong relationship (r2 = 0·88) indicated that aggregation levels are tightly constrained by mean infection levels, and that only a small proportion of the observed variability in parasite aggregation levels remains to be accounted for by other factors. Using the residuals of this regression as measures of ‘unexplained’ aggregation, a mixed effects model revealed no significant effect of within-sample variation in host body size or of parasite taxon or stage (i.e. juvenile versus adult) on parasite aggregation level within a sample. However, much of the remaining variability in parasite aggregation levels among samples was accounted for by the number of individual hosts examined per sample, and species-specific and study-specific effects reflecting idiosyncrasies of particular systems. This suggests that with most differences in aggregation among samples already explained, there may be little point in seeking universal causes for the remaining variation.

scholarly journals Relationships between water transparency and abundance of Cynodontidae species in the Bananal floodplain, Mato Grosso, Brazil

2009 ◽  
Vol 7 (2) ◽  
pp. 251-256 ◽  
Author(s):  
Cesar Enrique de Melo ◽  
Jane Dilvana Lima ◽  
Eliete Francisca da Silva
Keyword(s):  
Fish Assemblages ◽  
Water Transparency ◽  
Predatory Fish ◽  
Mato Grosso ◽  
Central Brazil ◽  
Fish Group ◽  
Species Specific ◽  
Abundance And Distribution ◽  
Number Of Individuals ◽  
Habitat Affinities

The Cerrado in the Central Brazil is currently one of the most threatened ecosystems in the world. As a result, the aquatic habitats in this biome also undergo great impacts. Alterations related to land-use change increase sediment loadings in rivers, streams and lakes, resulting in sedimentation and decrease in water transparency. Water transparency determines underwater visibility conditions, and as a consequence fish assemblages respond to spatial and temporal changes in this variable. This work aimed to examine the influence of transparency on the abundance and distribution of Cynodontidae species, a visually oriented predatory fish group. Fish sampling was conducted in 15 sites located between Mortes and Araguaia rivers in the Bananal floodplain, Mato Grosso State. Regression analysis between relative abundance of Cynodontidae (in number of individuals and biomass) and water transparency showed a positive and highly significant correlation, indicating that this group shows species-specific habitat affinities for clearer waters. These results suggest that the increase in water turbidity in this region can affect the patterns of abundance and distribution of the Cynodontidae species, as well as other visually oriented fishes.

scholarly journals Locally rare species influence grassland ecosystem multifunctionality

2016 ◽  
Vol 371 (1694) ◽  
pp. 20150269 ◽  
Author(s):  
Santiago Soliveres ◽  
Peter Manning ◽  
Daniel Prati ◽  
Martin M. Gossner ◽  
Fabian Alt ◽  
...  
Keyword(s):  
Land Use ◽  
Rare Species ◽  
Common Species ◽  
Ecosystem Functions ◽  
Individual Species ◽  
Conservation Priorities ◽  
Below Ground ◽  
Species Specific ◽  
The Relationship ◽  
Ecosystem Multifunctionality

Species diversity promotes the delivery of multiple ecosystem functions (multifunctionality). However, the relative functional importance of rare and common species in driving the biodiversity–multifunctionality relationship remains unknown. We studied the relationship between the diversity of rare and common species (according to their local abundances and across nine different trophic groups), and multifunctionality indices derived from 14 ecosystem functions on 150 grasslands across a land-use intensity (LUI) gradient. The diversity of above- and below-ground rare species had opposite effects, with rare above-ground species being associated with high levels of multifunctionality, probably because their effects on different functions did not trade off against each other. Conversely, common species were only related to average, not high, levels of multifunctionality, and their functional effects declined with LUI. Apart from the community-level effects of diversity, we found significant positive associations between the abundance of individual species and multifunctionality in 6% of the species tested. Species-specific functional effects were best predicted by their response to LUI: species that declined in abundance with land use intensification were those associated with higher levels of multifunctionality. Our results highlight the importance of rare species for ecosystem multifunctionality and help guiding future conservation priorities.

scholarly journals Patterns of fish utilisation in a tropical Indo-Pacific mangrove-coral seascape, New Caledonia

2018 ◽  
Author(s):  
A Dubuc ◽  
N. Waltham ◽  
R. Baker ◽  
C. Marchand ◽  
M. Sheaves
Keyword(s):  
Fish Assemblages ◽  
New Caledonia ◽  
Lunar Cycle ◽  
Forest Edge ◽  
Temporal Variations ◽  
Conservation Strategies ◽  
Small Scale ◽  
Mangrove Forests ◽  
Species Specific ◽  
Main Component

AbstractMangrove forests are important habitats for fish. However, their utilisation by fish, and the specific values they confer, are still not fully understood. This study describes how fish use mangrove forests in an Indo-Pacific mangrove-coral reef seascape. Sampling was conducted using underwater video cameras (UVCs) to describe spatial and temporal variations in fish assemblages across a small-scale (~ 2.5 km2) system, and over the tidal and lunar cycle. UVCs were deployed in the two main component habitats of mangrove forests: at the mangrove forest edge, and inside the forest (5 m from the forest edge), to establish patterns of utilisation of fish across the tidal and lunar cycle. Proximity to coral reefs had a strong influence on the mangrove fish community, as most fish recorded were reef-associated. Juveniles of 12 reef species were observed, including two species classified as vulnerable on the IUCN list, and one endemic species. Fish assemblages on the mangrove edge differed significantly from those inside the forest. Most fish utilised the forest edge, with few species making regular use of in-forest habitats, supporting the contention that most fish species remain on the edge and potentially retreat into the forest for opportunistic feeding, or when threatened by larger predators. Species-specific patterns of utilisation varied across the tidal and lunar cycle. Small differences in depth profiles and substrate across the small-scale system had a significant effect on fish assemblages, highlighting the importance of accounting for spatial heterogeneity in these factors. These data provide important information for managers to implement adequate conservation strategies that include broader interconnected habitat mosaics.

scholarly journals First record of the semi-slug Omalonyx unguis (d’Orbigny, 1837) (Gastropoda, Succineidae) in the Misiones Province, Argentina

Check List ◽  
2018 ◽  
Vol 14 (4) ◽  
pp. 705-712
Author(s):  
Leila B. Guzmán ◽  
Enzo N. Serniotti ◽  
Roberto E. Vogler ◽  
Ariel A. Beltramino ◽  
Alejandra Rumi ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Morphological Characteristics ◽  
First Record ◽  
Coi Gene ◽  
Cytochrome Oxidase Subunit ◽  
Specific Identification ◽  
Molluscan Fauna ◽  
Misiones Province ◽  
Species Specific ◽  
Northeastern Argentina

Omalonyx unguis (d’Orbigny, 1837) is a semi-slug inhabiting the Paraná river basin. This species belongs to Succineidae, a family comprising a few representatives in South America. In this work, we provide the first record for the species from Misiones Province, Argentina. Previous records available for Omalonyx in Misiones were identified to the genus level. We examined morphological characteristics of the reproductive system and used DNA sequences from cytochrome oxidase subunit I (COI) gene for species-specific identification. These new distributional data contribute to consolidate the knowledge of the molluscan fauna in northeastern Argentina.

scholarly journals Catch-per-unit-effort and size spectra of lake fish assemblages reflect underlying patterns in ecological conditions and anthropogenic activities across regional and local scales

2016 ◽  
Vol 73 (4) ◽  
pp. 535-546 ◽  
Author(s):  
Cindy Chu ◽  
Nigel P. Lester ◽  
Henrique C. Giacomini ◽  
Brian J. Shuter ◽  
Donald A. Jackson
Keyword(s):  
Body Size ◽  
Fish Assemblages ◽  
Anthropogenic Activities ◽  
Ecological Indicators ◽  
Size Spectrum ◽  
Catch Per Unit Effort ◽  
Ecological Processes ◽  
Boosted Regression Tree ◽  
Unit Effort ◽  
Lake Fish

Across broad geographic scales, ecological indicators for fish assemblages should represent causal ecological processes, be sensitive enough to show patterns across the landscape, and reflect underlying biotic or abiotic conditions that influence those patterns. We assessed the responses of commonly applied ecological indicators for lake fish assemblages (mean body size, catch-per-unit-effort (CPUE), and normalized length size spectrum (NLSS) slope) to regional (climate, water chemistry, and watershed stress due to human activities) and local (lake morphometry, water quality, and angling pressure) ecological and anthropogenic variables. The indicators were estimated using fish assemblage catch data acquired via a standardized gillnetting protocol implemented within 693 lakes in Ontario, Canada. To our knowledge, our study is the first size-based or catch-based indicator evaluation to include detailed observations of angling pressure on hundreds of inland lakes. Boosted regression tree models showed that CPUE of large-bodied organisms and NLSS slope best described underlying patterns in the regional and local variables. Models developed with a mix of regional and local variables performed better than models developed with regional or local variables alone. The relative influences of the variables and responses varied among indicators, but in general, ecological variables had greater influence on the indicators than anthropogenic variables. These results emphasize the complex and multiscaled nature of factors and ecological processes affecting body size, habitat-community production, and trophic dynamics in lake fish assemblages.

Pectoral fin locomotion in the striped surfperch. I. Kinematic effects of swimming speed and body size

1996 ◽  
Vol 199 (10) ◽  
pp. 2235-2242 ◽  
Author(s):  
E Drucker ◽  
J Jensen
Keyword(s):  
Body Size ◽  
Swimming Speed ◽  
Beat Frequency ◽  
Limited Range ◽  
The Body ◽  
Small Fish ◽  
Large Fish ◽  
Pectoral Fin ◽  
Transition Speed ◽  
Speed Up

Swimming trials at increasing velocity were used to determine the effects of steady swimming speed on pectoral fin kinematics for an ontogenetic series of striped surfperch Embiotoca lateralis, ranging from 6 to 23 cm in standard length (SL). The fin stroke cycle consisted of a propulsive period, the duration of fin abduction and adduction, and a 'refractory' period, during which the fin remained adducted against the body. Pectoral fin-beat frequency (fp) measured as the inverse of the entire stride period, as in past studies, increased curvilinearly with speed. Frequency, calculated as the reciprocal of the propulsive period alone, increased linearly with speed, as shown previously for tail-beat frequency of fishes employing axial undulation. Fin-beat amplitude, measured as the vertical excursion of the pectoral fin tip during abduction, increased over a limited range of low speeds before reaching a plateau at 0.35&shy;0.40 SL. Pectoral fin locomotion was supplemented by intermittent caudal fin undulation as swimming speed increased. At the pectoral&shy;caudal gait transition speed (Up-c), frequency and amplitude attained maxima, suggesting that the fin musculature reached a physiological limit. The effects of body size on swimming kinematics differed according to the method used for expressing speed. At a given absolute speed, small fish used higher stride frequencies and increased frequency at a faster rate than large fish. In contrast, the relationship between fp and length-specific speed (SL s-1) had a greater slope for large fish and crossed that for small fish at high speeds. We recommend that comparisons across size be made using speeds expressed as a percentage of Up-c, at which kinematic variables influencing thrust are size-independent.

scholarly journals Seascape context modifies how fish respond to restored oyster reef structures

2019 ◽  
Vol 76 (4) ◽  
pp. 1131-1139 ◽  
Author(s):  
Ben L Gilby ◽  
Andrew D Olds ◽  
Christopher J Henderson ◽  
Nicholas L Ortodossi ◽  
Rod M Connolly ◽  
...  
Keyword(s):  
Species Richness ◽  
Fish Species ◽  
Fish Assemblages ◽  
Oyster Reef ◽  
Pivotal Role ◽  
Oyster Reefs ◽  
Total Abundance ◽  
Fish Recruitment ◽  
Abundance And Diversity ◽  
Species Specific

Abstract The seascape context of coastal ecosystems plays a pivotal role in shaping patterns in fish recruitment, abundance, and diversity. It might also be a principal determinant in structuring the recruitment of fish assemblages to restored habitats, but the trajectories of these relationships require further testing. In this study, we surveyed fish assemblages from 14 restored oyster reefs and 14 control sites in the Noosa River, Queensland, Australia, that differed in the presence or absence of seagrass within 500 m, over four periods using baited cameras. Fish assemblages at oyster reefs differed from those at control sites, with higher species richness (1.4 times) and more individuals of taxa that are harvested by fishers (1.8 times). The presence or absence of seagrass nearby affected the abundance of a key harvestable fish species (yellowfin bream Acanthopagrus australis) on oyster reefs, but not the overall composition of fish assemblages, species richness, or the total abundance of harvestable fishes overall. These findings highlight the importance of considering species-specific patterns in seascape utilization when selecting restoration sites and setting restoration goals, and suggest that the effects of restoration on fish assemblages might be optimized by focusing efforts in prime positions in coastal seascapes.

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