Factors influencing Fish Assemblages and Species Richness in Subtropical Florida Lakes and a Comparison with Temperate Lakes

1990 ◽  
Vol 47 (11) ◽  
pp. 2137-2146 ◽  
Author(s):  
A. E. Keller ◽  
T. L. Crisman
Keyword(s):  
Species Richness ◽  
Littoral Zone ◽  
Trophic State ◽  
Fish Assemblages ◽  
Temperate Lakes ◽  
Florida Lakes ◽  
Factors Influencing ◽  
Dissolved Aluminum ◽  
The Impact ◽  
Lake Size

From detailed analyses of 36 lakes, we determined that while species assemblages and richness change with lake size, trophic state, and pH, the responses were not as dramatic in Florida as in temperate lakes. At a given pH, there were more species in Florida lakes than in comparable lakes of the temperate zone. The impact of lake size on species richness was also less obvious in Florida lakes. The greater importance of centrarchids, increased contribution of the littoral zone to primary production, and lower dissolved aluminum levels may contribute to greater species richness in Florida lakes than in temperate lakes of comparable pH or size.

scholarly journals Impacts of small-scale fisheries on mangrove fish assemblages

2018 ◽  
Vol 76 (1) ◽  
pp. 153-164 ◽  
Author(s):  
José Amorim Reis-Filho ◽  
Euan S Harvey ◽  
Tommaso Giarrizzo
Keyword(s):  
Species Richness ◽  
Fishery Management ◽  
Management Practices ◽  
Fish Assemblages ◽  
Small Scale ◽  
Fishing Pressure ◽  
Community Size ◽  
Small Scale Fisheries ◽  
Fishing Impacts ◽  
The Impact

Abstract The data requirements and resources needed to develop effective indicators of fishing impacts on target stocks may often be great, especially for mangrove fisheries where, for example, tidal cycles sequentially flood and drain the habitat as a result of natural processes. Here, we used underwater video systems to evaluate the impact of small-scale fisheries on mangrove fish assemblages at four levels of fishing pressure (low, medium, high, and no pressure). The lowest values of species richness and abundance were recorded in the areas fished most intensively. Conversely, the highest species richness and the occurrence of larger-bodied fish were recorded in areas of reduced fishing activity, which was surprisingly similar to the “no fishing” areas. The slopes of the community size spectra steepened in response to exploitation, while the relative abundance of medium-sized fish (16–25 cm) declined. Fishing for local or regional markets, rather than subsistence, also led to a decrease in the abundance of larger fish (>41 cm). The marked response of population parameters to fishing pressure reflected the impact of unregulated small-scale fisheries on areas of mangroves. Fishery management practices that ignore contemporary changes in these environments are likely to overestimate long-term yields, leading to overfishing. Thus, size-based approaches to evaluating fishing pressure were suitable for detecting negative responses from the mangrove fish assemblages. A next step will be to integrate size- and species-based ecological approaches that provide mechanisms to address pronounced decreases in specific species as a more profitable indicator of fishing impacts on mangrove fish assemblages. This approach will allow the development of effective conservation and management strategies.

scholarly journals Trophic state (TSISD) and mixing type significantly influence pelagic zooplankton biodiversity in temperate lakes (NW Poland)

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e5731 ◽  
Author(s):  
Łukasz Sługocki ◽  
Robert Czerniawski
Keyword(s):  
Trophic State ◽  
Thermal Structure ◽  
Shannon Index ◽  
Freshwater Ecosystems ◽  
Trophic State Index ◽  
Lake Depth ◽  
Temperate Lakes ◽  
Secchi Disc ◽  
Mixing Regime ◽  
The Impact

BackgroundLake depth and the consequent mixing regime and thermal structure have profound effects on ecosystem functioning, because depth strongly affects the availability of nutrients, light, and oxygen. All these conditions influence patterns of zooplankton diversity. Zooplankton are a key component of the aquatic environment and are essential to maintaining natural processes in freshwater ecosystems. However, zooplankton biodiversity can be different regard to depth, mixing type and trophic state. Therefore, the aim of this study was to examine how depth and mixing regime affect zooplankton diversity in lakes. We also investigated the vertical distribution of diversity across a trophic gradient of lakes.MethodsA total of 329 zooplankton samples from 79 temperate lakes (36 polymictic and 43 dimictic) were collected. The biodiversity of zooplankton was calculated using species richness (SR) and the Shannon index (SI). An index based on Secchi disc visibility was used to determine the trophic state index (TSISD) of lakes. The one-way ANOVA with Duncan’s post hoc test were used to determine differences in zooplankton biodiversity between mictic lake types and thermal layers. To find the best predictors for zooplankton biodiversity a multiple stepwise regression was used. The rarefaction method was used to evaluate the impact of mixing types, thermal layers, and the TSISDon zooplankton biodiversity indices. A Sørensen similarity analysis and nonmetric multidimensional scaling (NMDS) were performed to describe the similarity patterns in species composition among lakes.ResultsWe identified a total of 151 taxa from 36 polymictic and 43 dimictic lakes. Lake depth and the TSISDwere significantly correlated with the biodiversity of lake zooplankton. The results of ANOVA and Duncan tests show that mictic type and thermal zones had a significant effect on zooplankton biodiversity. The rarefaction curve showed significant differences in zooplankton biodiversity, which was greater in lakes with lower trophic state. Ordination by NMDS showed clustering of different mictic types, thermal layers, and composition changes throughout the TSISDprofile. Moreover, we determined that polymictic lakes are more heterogeneous than dimictic lakes in regard to zooplankton similarities.DiscussionBoth mictic lake types were characterized by varying levels of zooplankton biodiversity, which is shaped by the communities’ response to lake depth, thermal layers and TSISDvalues. The zooplankton SR and SI (during daylight hours) depends greatly on the mixing type. Lake type also indicates the importance of the metalimnion in shaping zooplankton biodiversity in dimictic lakes. In addition, data from NW Polish lakes indicated that the increase of the TSISDleads to taxonomic shifts and has a negative effect on the diversity of all groups of zooplankton.

The influence of smallmouth bass (Micropterus dolomieu) predation and habitat complexity on the structure of littoral zone fish assemblages

2001 ◽  
Vol 58 (2) ◽  
pp. 342-351 ◽  
Author(s):  
Pamela SD MacRae ◽  
Donald A Jackson
Keyword(s):  
Habitat Complexity ◽  
Littoral Zone ◽  
Fish Assemblages ◽  
Pimephales Promelas ◽  
Visual Assessment ◽  
Smallmouth Bass ◽  
Micropterus Dolomieu ◽  
Culaea Inconstans ◽  
Brook Stickleback ◽  
The Impact

Fish assemblages in small lakes ([Formula: see text]50 ha) in central Ontario were characterized to determine the impact of smallmouth bass (Micropterus dolomieu) predation and habitat complexity on the structure of littoral zone fish assemblages. Data were collected employing minnow traps and visual assessment. Although species richness did not differ between lakes with and without smallmouth bass, species composition and relative abundance did differ. We identified two distinct fish assemblage types: one characterized by small-bodied species, mainly cyprinids, and a second by large-bodied centrarchid species, e.g., smallmouth bass. Smallmouth bass appear to reduce abundance, alter habitat use, and extirpate many small-bodied species such as brook stickleback (Culaea inconstans), fathead minnow (Pimephales promelas), pearl dace (Margariscus margarita), and Phoxinus spp.

How to Psychologically Minimize Scratching Impulses

2014 ◽  
Vol 222 (3) ◽  
pp. 140-147 ◽  
Author(s):  
Ariane Sölle ◽  
Theresa Bartholomäus ◽  
Margitta Worm ◽  
Regine Klinger
Keyword(s):  
Cognitive Processes ◽  
Placebo Effect ◽  
Psychological Factors ◽  
Pharmacological Treatments ◽  
Physiological Basis ◽  
Psychological Mechanisms ◽  
Physical Complaints ◽  
Factors Influencing ◽  
The Impact ◽  
Placebo Model

Research in recent years, especially in the analgesic field, has intensively studied the placebo effect and its mechanisms. It has been shown that physical complaints can be efficiently reduced via learning and cognitive processes (conditioning and expectancies). However, despite evidence demonstrating a large variety of physiological similarities between pain and itch, the possible transfer of the analgesic placebo model to itch has not yet been widely discussed in research. This review therefore aims at highlighting potential transfers of placebo mechanisms to itch processes by demonstrating the therapeutic issues in pharmacological treatments for pruritus on a physiological basis and by discussing the impact of psychological mechanisms and psychological factors influencing itch sensations.

scholarly journals Modelling natural regeneration of European beech in Saxony, Germany: identifying factors influencing the occurrence and density of regeneration

2021 ◽  
Author(s):  
Maximilian Axer ◽  
Sven Martens ◽  
Robert Schlicht ◽  
Sven Wagner
Keyword(s):  
Natural Regeneration ◽  
Negative Binomial ◽  
European Beech ◽  
Seed Source ◽  
Permanent Plots ◽  
Forest Conversion ◽  
Ecological Knowledge ◽  
Statistical Tool ◽  
Factors Influencing ◽  
The Impact

AbstractThe potential utilisation of natural regeneration of European beech (Fagus sylvatica L.) for forest conversion has received little attention to date. Ecological knowledge is necessary to understand and predict successful natural regeneration of beech. The objective of this study was to improve understanding of what drives the occurrence of beech regeneration and, once regeneration is present, what drives its density. In the study, we utilised a forest inventory dataset provided by Sachsenforst, the state forestry service of Saxony, Germany. The dataset was derived from 8725 permanent plots. Zero-altered negative binomial models (ZANB) with spatial random effects were used to analyse factors influencing occurrence and density simultaneously. The results provided by the spatial ZANB models revealed that the probability of the occurrence of beech regeneration is highly dependent on seed availability, i.e. dependent on source trees in close proximity to a plot. The probability of beech regeneration rises with the increasing diameter of a potential seed tree and decreases with increasing distance to the nearest potential seed source. The occurrence of regeneration is affected by overstorey composition and competition exerted by spruce regeneration. Where sites are affected by groundwater or temporary waterlogging, the impact on the occurrence of regeneration is negative. Although distance to the nearest potential seed source has an influence on occurrence, this variable exerts no influence on density. A high regeneration density arises in conjunction with a high beech basal area in the overstorey. Beech regeneration density, but not occurrence, is negatively affected by browsing intensity. These variables can be used to predict the occurrence and density of beech regeneration in space to a high level of precision. The established statistical tool can be used for decision-making when planning forest conversion using natural regeneration.

scholarly journals Individual Condensation Trails in Aircraft Trajectory Optimization

2019 ◽  
Vol 11 (21) ◽  
pp. 6082 ◽  
Author(s):  
Judith Rosenow ◽  
Hartmut Fricke
Keyword(s):  
Global Warming ◽  
Trajectory Optimization ◽  
Wind Shear ◽  
Impact Factors ◽  
Factors Influencing ◽  
Order Of Magnitude ◽  
Aircraft Trajectory ◽  
The Impact ◽  
Arbitrary Trajectory ◽  
Significant Factors

Contrails are one of the driving contributors to global warming, induced by aviation. The quantification of the impact of contrails on global warming is nontrivial and requires further in-depth investigation. In detail, condensation trails might even change the algebraic sign between a cooling and a warming effect in an order of magnitude, which is comparable to the impact of aviation-emitted carbon dioxides and nitrogen oxides. This implies the necessity to granularly consider the environmental impact of condensation trails in single-trajectory optimization tools. The intent of this study is the elaboration of all significant factors influencing on the net effect of single condensation trails. Possible simplifications will be proposed for a consideration in single-trajectory optimization tools. Finally, the effects of the most important impact factors, such as latitude, time of the year, and time of the day, wind shear, and atmospheric turbulence as well as their consideration in a multi-criteria trajectory optimization tool are exemplified. The results can be used for an arbitrary trajectory optimization tool with environmental optimization intents.

scholarly journals Facilitation Effects of Haloxylon salicornicum Shrubs on Associated Understory Annuals, and a Modified “Stress-Gradient” Hypothesis for Droughty Times

Plants ◽  
2020 ◽  
Vol 9 (12) ◽  
pp. 1726
Author(s):  
Nasr H. Gomaa ◽  
Ahmad K. Hegazy ◽  
Arafat Abdel Hamed Abdel Latef
Keyword(s):  
Species Richness ◽  
Water Availability ◽  
Stress Gradient ◽  
Growing Season ◽  
Annual Species ◽  
Negative Effects ◽  
Growing Seasons ◽  
Dry Seasons ◽  
The Impact ◽  
Haloxylon Salicornicum

Perennial shrub-annual plant interactions play key roles in desert regions influencing the structure and dynamics of plant communities there. In the present study, carried out in northwestern Saudi Arabia, we examined the effect of Haloxylon salicornicum shrubs on their associated understory annual species across four consecutive growing seasons, along with a record of the seasonal rainfall patterns. We measured density and species richness of all the annual species in permanent quadrats located beneath individual shrubs, as well as in the spaces between shrubs. During wet growing season H. salicornicum shrubs significantly enhanced the density and species richness of sub-canopy species, whereas in the relatively dry seasons they exerted negative effects on the associated species. In all growing seasons, the presence of shrubs was associated with enhanced soil properties, including increased organic carbon content, silt + clay, and levels of nutrients (N, P and K). Shrubs improved soil moisture content beneath their canopies in the wet growing season, while in the dry seasons they had negative effects on water availability. Differences in effects of H. salicornicum on understory plants between growing seasons seem due to the temporal changes in the impact of shrubs on water availability. Our results suggest the facilitative effects of shrubs on sub-canopy annuals in arid ecosystems may switch to negative effects with increasing drought stress. We discuss the study in light of recent refinements of the well-known “stress-gradient hypothesis”.

Cyprinid distributions in Northeast U.S.A. lakes: evidence of regional-scale minnow biodiversity losses

1997 ◽  
Vol 54 (7) ◽  
pp. 1593-1607 ◽  
Author(s):  
T R Whittier ◽  
D B Halliwell ◽  
S G Paulsen
Keyword(s):  
New York ◽  
Species Richness ◽  
New England ◽  
Fish Assemblages ◽  
Regional Scale ◽  
Median Number ◽  
Southern New England ◽  
Sample Data ◽  
Golden Shiner ◽  
Northern New England

Fish assemblages were sampled in 195 randomly selected lakes in the northeastern United States during the summers of 1991-1994. Most lakes in northern Maine had three to seven minnow species, constituting 40-80% of species in each lake. Lakes in New Jersey, southern New York, and southern New England rarely had minnows, other than golden shiner (Notemigonus crysoleucas). Lakes in the Adirondacks and the remainder of northern New England had intermediate numbers. We examined minnow native ranges and autecology and evaluated species richness related to littoral predators and human disturbance. Sample data suggested alteration in the minnow assemblages over much of the region. The most consistent factor related to minnow species richness was the presence of littoral predators. Median number of minnow species was two in lakes lacking predators and zero in lakes with predators. Non-native predators, especially Micropterus spp., have been introduced throughout the Northeast; 69% of the sampled lakes had non-native predators. In the absence of predators, minnow species declined with increased human activity in the watershed and along lake shorelines. Only in northern Maine did lake minnow assemblages seem relatively intact.

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