The influence of environmental conditions on Parasagitta friderici (Chaetognatha) abundance in a subtropical estuary (south Brazil)

2018 ◽  
Vol 99 (4) ◽  
pp. 785-793
Author(s):  
Miodeli Nogueira Júnior ◽  
Everton Giachini Tosetto ◽  
Emanuel Luís Razzolini
Keyword(s):  
Food Availability ◽  
Zooplankton Biomass ◽  
Early Summer ◽  
Additive Models ◽  
Low Salinity ◽  
Juvenile Abundance ◽  
Subtropical Estuary ◽  
Estuarine Systems ◽  
South Brazil ◽  
General Additive Models

AbstractEstuarine chaetognath population dynamics are poorly known worldwide. We have conducted eight seasonal campaigns (October 2007–August 2008) sampling three sectors in the subtropical Babitonga Bay estuary (26°S 48°W) in order to depict chaetognath abundance and population structure dynamics and test the influence of hydrography and food availability and type. Of three species sampled, Parasagitta friderici represented >93% of abundance in all samples and was examined in detail. There were no differences in P. friderici abundance between the sectors of the estuary, related to its high tolerance to low salinity, a feature not common for most chaetognath species. Salinity tolerance is an important adaptive characteristic to thrive within estuarine systems, and probably is responsible for the dominance of P. friderici in coastal and brackish water environments throughout most of its distribution. Juveniles dominated the population most of the year, except in February–April when abundances were lower and adults predominated. These results suggest that recruitment occurs continuously throughout the year, being more intense between October and January (spring to early summer) and in May (autumn) when densities and proportion of juveniles were higher. General Additive Models suggest that temperature and zooplankton biomass are significant (P < 0.05) factors influencing juvenile abundance while only the latter influenced the adults. We conclude that food availability is the most important driver in the studied population of P. friderici and recruitment peaks, which lead to high densities, seem to occur following peaks of their copepod prey along with particular temperature conditions (22–23°C).

Spatial and seasonal variability of emergent aquatic insects and nearshore spiders in a subtropical estuary

2019 ◽  
Vol 70 (4) ◽  
pp. 541 ◽  
Author(s):  
Martha J. Zapata ◽  
S. Mažeika P. Sullivan
Keyword(s):  
Aquatic Insects ◽  
High Salinity ◽  
Aquatic Insect ◽  
Freshwater Ecosystems ◽  
Dispersal Ability ◽  
Insect Community ◽  
Insect Communities ◽  
Low Salinity ◽  
Subtropical Estuary ◽  
Adult Aquatic Insects

Variability in the density and distribution of adult aquatic insects is an important factor mediating aquatic-to-terrestrial nutritional subsidies in freshwater ecosystems, yet less is understood about insect-facilitated subsidy dynamics in estuaries. We surveyed emergent (i.e. adult) aquatic insects and nearshore orb-weaving spiders of the families Tetragnathidae and Araneidae in a subtropical estuary of Florida (USA). Emergent insect community composition varied seasonally and spatially; densities were lower at high- than low-salinity sites. At high-salinity sites, emergent insects exhibited lower dispersal ability and a higher prevalence of univoltinism than low- and mid-salinity assemblages. Orb-weaving spider density most strongly tracked emergent insect density rates at low- and mid-salinity sites. Tetragnatha body condition was 96% higher at high-salinity sites than at low-salinity sites. Our findings contribute to our understanding of aquatic insect communities in estuarine ecosystems and indicate that aquatic insects may provide important nutritional subsidies to riparian consumers despite their depressed abundance and diversity compared with freshwater ecosystems.

scholarly journals Spatial and temporal differences in the fish assemblage structure in a subtropical estuary

2020 ◽  
Vol 48 (1) ◽  
pp. 74-84
Author(s):  
André P. Cattani ◽  
Gisela C. Ribeiro ◽  
Mauricio Hostim-Silva ◽  
Marcelo Soeth ◽  
Leandro Clezar ◽  
...  
Keyword(s):  
Food Availability ◽  
Fish Assemblage ◽  
Spatial Dynamics ◽  
River Estuary ◽  
Fish Assemblage Structure ◽  
Southern Brazil ◽  
Pomatomus Saltatrix ◽  
Subtropical Estuary ◽  
Micropogonias Furnieri ◽  
Temporal And Spatial

A large number of fish species use the mangrove mainly due to food availability and protection against predators. The knowledge of temporal and spatial dynamics of ichthyofauna allows us to identify patterns of occupation of this ecosystem and to support the assessment and preservation of local biodiversity. In this sense, samplings were conducted in 1988 at five areas of the Itacorubi River estuary, Santa Catarina Island. A total of 3,883 specimens were collected, distributed in 21 families and 41 species with the predominance of Cetengraulis edentulus, Mugil liza, Mugil curema, Genidens genidens, Mugil gaimardianus, Eucinostomus gula, Micropogonias furnieri, Pomatomus saltatrix and Sphoeroides testudineus. On average, abundances differed between seasons and sampled areas. Differences were detected between the fish faunas of fall and winter compared to summer and spring and between sampling sites. This study identified a fish assemblage in the mangrove of the Itacorubi River with a similar structure to other estuaries of southern Brazil.

scholarly journals Essential habitat for sardine juveniles in Iberian waters

2017 ◽  
Vol 81 (3) ◽  
pp. 351 ◽  
Author(s):  
Sílvia Rodríguez-Climent ◽  
Maria Manuel Angélico ◽  
Vítor Marques ◽  
Paulo Oliveira ◽  
Laura Wise ◽  
...  
Keyword(s):  
Fishery Management ◽  
Generalized Additive Models ◽  
Management Strategies ◽  
Coastal Region ◽  
Additive Models ◽  
Spawning Grounds ◽  
Significant Relationships ◽  
Juvenile Abundance ◽  
Spatial Differences ◽  
Core Areas

In a period when the Iberian sardine stock abundance is at its historical minimum, knowledge of the sardine juvenile’s distribution is crucial for the development of fishery management strategies. Generalized additive models were used to relate juvenile sardine presence with geographical variables and spawning grounds (egg abundance) and to model juvenile abundance with the concurrent environmental conditions. Three core areas of juvenile distribution were identified: the Northern Portuguese shelf (centred off Aveiro), the coastal region in the vicinity of the Tagus estuary, and the eastern Gulf of Cadiz. Spatial differences in the relationship between juvenile presence and egg abundances suggest that essential juvenile habitat might partially differ from the prevailing spawning grounds. Models also depicted significant relationships between juvenile abundance, temperature and geographical variables in combination with salinity in the west and with zooplankton in the south. Results indicate that the sardine juvenile distribution along the Iberian Peninsula waters are an outcome of a combination of dynamic processes occurring early in life, such as egg and larva retention, reduced mortality and favourable feeding grounds for both larvae and juveniles.

Interdecadal variation in developmental timing of Neocalanus plumchrus populations at Ocean Station P in the subarctic North Pacific

1998 ◽  
Vol 55 (8) ◽  
pp. 1878-1893 ◽  
Author(s):  
David L Mackas ◽  
Robert Goldblatt ◽  
Alan G Lewis
Keyword(s):  
Large Scale ◽  
Zooplankton Biomass ◽  
Early Summer ◽  
Individual Development ◽  
Developmental Timing ◽  
Upper Ocean ◽  
Surface Mixed Layer ◽  
Mesozooplankton Biomass ◽  
Annual Peak ◽  
Neocalanus Plumchrus

A single copepod species, Neocalanus plumchrus (Marukawa), makes up much of the mesozooplankton biomass in the subarctic Pacific. Its vertical distribution and developmental sequence are both strongly seasonal. Together, they produce a strong and narrow (<60 days duration) annual peak of upper ocean zooplankton biomass in spring and early summer. At Ocean Station P (50°N, 145°W), seasonal phasing of this annual maximum has shifted dramatically between 1956 and the present. Both time series observations of N. plumchrus stage composition ratios and measurements of total upper ocean zooplankton biomass produce consistent pictures of this change. Population development was very late in the early 1970s (biomass maximum in mid-July to late July), early in the late 1950s (late May - early June), and very early in the 1990s (early May to mid-May). The changes in timing are strongly correlated with large-scale year-to-year and decade-to-decade ocean climate fluctuations, as reflected by spring season temperature anomalies in the surface mixed layer within which the juvenile copepodites feed and grow (r2 = 0.56, development about 60 days earlier in warm than in cold years). But the change in developmental timing is too large to be explained solely by physiological acceleration of individual development rate. We suggest instead that the cause is interannual differences in survival among early versus late portions of the annual copepodite cohort.

Hierarchical interpretation of nonlinear relationships linking yellowfin tuna (Thunnus albacares) distribution to the environment in the Atlantic Ocean

2001 ◽  
Vol 58 (3) ◽  
pp. 458-469 ◽  
Author(s):  
Olivier Maury ◽  
Didier Gascuel ◽  
Francis Marsac ◽  
Alain Fonteneau ◽  
Anne-Laure De Rosa
Keyword(s):  
Adult Population ◽  
Yellowfin Tuna ◽  
Additive Models ◽  
Small Scale ◽  
Physical Factors ◽  
Thunnus Albacares ◽  
Catch Per Unit Effort ◽  
Low Salinity ◽  
Nonlinear Relationships ◽  
Unit Effort

Using generalized additive models, we show evidence for nonlinear relationships between various hydrological factors and age-structured catch per unit effort of Atlantic yellowfin tuna (Thunnus albacares) for two fishing fleets. Catchability effects are distinguished from tuna environmental preference effects in the catch per unit effort variability. With respect to catchability, an important nonlinear effect of local fishing effort is highlighted for each fleet. It is interpreted as resulting from a local overfishing phenomenon of adult yellowfin tuna and from vessel fishing tactics (cooperation/spying). The environmental preferences obtained facilitate the interpretation of the hierarchical spatial distribution and age-dependent movements of the yellowfin population. We show that, on a large spatiotemporal scale (the whole ocean), low salinity is a good predictor of yellowfin habitat. Juveniles are mainly distributed in low-salinity waters (<0.035 kg·kg–1) when adults extend their range to waters of 0.036 kg·kg–1. On a mesoscale, adult population annual reproductive transatlantic displacements are probably driven by temperature and salinity gradients to warm and low-salinity locations that are favorable for juveniles. North–south seasonal movements of the population are clearly related to warmwater seasonal oscillations. On a small scale, ocean thermic stability and gradients of sea surface temperature are important physical factors determining yellowfin concentration.

scholarly journals Habitat Suitability Curves for Freshwater Macroinvertebrates of Tropical Andean Rivers

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2703
Author(s):  
Raúl Vázquez ◽  
Diego Vimos-Lojano ◽  
Henrietta Hampel
Keyword(s):  
Habitat Suitability ◽  
Feeding Habits ◽  
Additive Models ◽  
Physical Habitat ◽  
Aquatic Biota ◽  
Physical Chemical ◽  
Main River ◽  
Flowing Waters ◽  
General Additive Models ◽  
Habitat Variables

Sustainable river management requires a thorough understanding of the response of aquatic biota to riverine microhabitat variability. The purpose of this study was to assess macroinvertebrate hydraulic-habitat suitability in Ecuadorian Andean rivers to support habitat modelling for sustainable ecosystem management. 597 macroinvertebrate samples were collected from ten sampling stations the Yanuncay River, Ecuador. Physical, chemical, hydraulic and habitat variables were measured/calculated. Froude number, Reynolds number, substrate index and algae coverage were major drivers of macroinvertebrate response, and were used to develop suitability curves for Baetodes, Andesiops, Camelobaetidius, Ecuaphlebia, Anacroneuria, Atopsyche, Simulium and Palpomyia using General Additive Models. Standardised density contours of taxa as functions of hydraulic and habitat variables were also developed. Taxonomic response was related to body structures/shapes and feeding habits. Baetodoes, Simulium, Anacroneuria and Atopsyche preferred fast flowing waters, and thus, they could be significantly affected in case of flow reduction. Similar habitat suitability curves were developed from the main river and the tributaries, possibly due to the short distance between the sampling stations. This study fills a major knowledge gap by developing macroinvertebrate habitat suitability curves for future physical habitat simulations and environmental flow assessments in the Andean region.

scholarly journals Maximal Fully Tethered Swim Performance in Para Swimmers With Physical Impairment

2020 ◽  
Vol 15 (6) ◽  
pp. 816-824
Author(s):  
Luke Hogarth ◽  
Brendan Burkett ◽  
Peter Van de Vliet ◽  
Carl Payton
Keyword(s):  
Muscle Power ◽  
Objective Assessment ◽  
Significant Proportion ◽  
Additive Models ◽  
Physical Impairment ◽  
Swim Performance ◽  
Positive Correlations ◽  
Competitive Swimmers ◽  
Limb Deficiency ◽  
General Additive Models

The assessment of swimming propulsion should be a cornerstone of Paralympic swimming classification. However, current methods do not objectively account for this component. Purpose: To evaluate the swimming propulsion of swimmers with and without physical impairment using a 30-second maximal fully tethered freestyle swim test. Methods: Tethered forces were recorded during maximal fully tethered swimming in 80 competitive swimmers with (n = 70) and without (n = 10) physical impairment. The relationships between absolute and normalized tether forces and maximal freestyle swim speed were established using general additive models. Results: Para swimmers with physical impairment had lower absolute and normalized tether forces than able-bodied swimmers, and there were moderate positive correlations found between tether forces and sport class (τ = .52–.55, P < .001). There was a nonlinear relationship between tether force and maximal freestyle swim speed in the participant cohort (adjusted R2 = .78–.80, P < .001). Para swimmers with limb deficiency showed stronger relationships between tether force and maximal freestyle swim speed (adjusted R2 = .78–.82, P < .001) than did Para swimmers with hypertonia (adjusted R2 = .54–.73, P < .001) and impaired muscle power (adjusted R2 = .61–.70, P < .001). Conclusions: Physical impairments affect Para swimmers’ tether forces during maximal fully tethered freestyle swimming, explaining a significant proportion of their activity limitation. It is recommended that maximal fully tethered swimming be included in Paralympic swimming classification as an objective assessment of swimming propulsion.

scholarly journals Modelling and predicting low count child asthma hospital readmissions using General Additive Models

2013 ◽  
Vol 03 (03) ◽  
pp. 125-134 ◽  
Author(s):  
Don Vicendese ◽  
Andriy Olenko ◽  
Shyamali Dharmage ◽  
Mimi Tang ◽  
Michael Abramson ◽  
...  
Keyword(s):  
Hospital Readmissions ◽  
Additive Models ◽  
Child Asthma ◽  
General Additive Models

Environmental and biological factors associated with the stage-specific abundance of brown shrimp (Penaeus aztecus) in Louisiana: applying a new combination of statistical techniques to long-term monitoring data

2001 ◽  
Vol 58 (11) ◽  
pp. 2258-2270 ◽  
Author(s):  
Heather L Haas ◽  
E Conrad Lamon III ◽  
Kenneth A Rose ◽  
Richard F Shaw
Keyword(s):  
Bayesian Model Averaging ◽  
Explanatory Power ◽  
Additive Models ◽  
Brown Shrimp ◽  
Small Scale ◽  
Nonlinear Relationships ◽  
Penaeus Aztecus ◽  
Juvenile Abundance ◽  
Abundance Estimates ◽  
Correlative Studies

Several short-term and small-scale correlative studies have associated brown shrimp (Penaeus aztecus) recruitment with high densities of sub-adults, high salinity, warm temperature, low river flow, and low precipitation. In this paper, we address criticisms of traditional correlative studies by using a spatially and temporally extensive dataset, by comparing stepwise multiple regression (SMR) to Bayesian model averaging (BMA), and by investigating nonlinear relationships with generalized additive models (GAMs). We use this combination of statistical methods to examine relationships between annual, stage-specific abundance estimates and environmental factors. BMA and SMR resulted in models with similar explanatory power, but BMA suggested fewer linear predictors. GAMs did not suggest nonlinear relationships among stage-specific abundance estimates. Postlarval abundance was not well described by any model. Juvenile abundance was partially described by environmental variables such as temperature, water clarity, and water level. Adult abundance was well described by early-juvenile abundance, salinity, and temperature. These results suggest that juvenile abundance may be the critical component in determining year-class strength of brown shrimp. Identifying mechanisms that regulate juvenile production within the estuary will be a critical step in effectively managing Louisiana's brown shrimp resource.

Timing of breeding in subarctic passerines in relation to food availability

2000 ◽  
Vol 78 (1) ◽  
pp. 67-78 ◽  
Author(s):  
Tapio Eeva ◽  
Simo Veistola ◽  
Esa Lehikoinen
Keyword(s):  
Food Availability ◽  
Bird Species ◽  
Weather Conditions ◽  
Early Summer ◽  
Egg Laying ◽  
Pied Flycatcher ◽  
Food Sources ◽  
Laying Date ◽  
Timing Of Breeding ◽  
Nestling Period

We studied timing of breeding in four species of hole-nesting passerines, the Siberian tit (Poecile cinctus), great tit (Parus major), pied flycatcher (Ficedula hypoleuca), and redstart (Phoenicurus phoenicurus), and the abundance of the arthropods in their diet (ground-dwelling spiders, winged insects, foliage-feeding lepidopteran and hymenopteran larvae) in Finnish Lapland for 6-12 years. Densities of the invertebrate groups varied considerably, both seasonally and annually. All the bird species started to breed in early summer, when weather conditions were often poor. At the beginning of the breeding season all species relied on ground-dwelling spiders, whose abundances peaked early and were less variable over the years than those of insects. Abundances and timing of emergence of caterpillars in birch and pine canopies (the major food sources for foliage-gleaners) were highly variable, but each year their abundances peaked in July or August, after the nestling period of the birds. This contrasts with reported cases in deciduous forests at midlatitudes and shows that at our site the birds did not time their nestling period ultimately to coincide with peak food availability. Mean clutch sizes declined seasonally in the tit species and the pied flycatcher but not in the redstart. The number of fledglings did not depend on laying date, except in the Siberian tit, for which dependence of fledgling number on laying date varied among years. Although early broods were not more productive (i.e., greater number of fledglings) than later ones, early breeding is ultimately a necessity for recruitment because of the short subarctic summer. Birds cannot delay breeding in the north because late breeding would shorten the time available for moulting, food-hoarding, and preparation for migration or wintering. Our results show that at the time of egg laying, passerines may receive proximate cues to allow them to predict food conditions during the nestling period. Still, exact prediction of food availability during later phases of nesting is constrained by an inherent discrepancy between warm-blooded birds and poikilothermic invertebrates: once a bird has started egg laying, the subsequent phases follow nearly automatically on certain calendar dates, whereas the development of the arthropods depends on the rate of temperature increase.

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