scholarly journals Not all sawsharks are equal: species of co-existing sawsharks show plasticity in trophic consumption both within and between species

2015 ◽  
Vol 72 (11) ◽  
pp. 1769-1775 ◽  
Author(s):  
Vincent Raoult ◽  
Troy F. Gaston ◽  
Jane E. Williamson
Keyword(s):  
Resource Partitioning ◽  
Management Strategies ◽  
Isotopic Analysis ◽  
Trophic Levels ◽  
Multiple Functions ◽  
Isotopic Signatures ◽  
As Species ◽  
Primary Consumers ◽  
Marine Biosphere ◽  
Conservation And Management

Despite the global distribution of sawsharks, little is known about their diets or their role in the marine biosphere. As species in higher trophic positions are generally considered to be more at risk to perturbations such as fishing, understanding their role in the food chain will enable better conservation and management strategies for these species. Two sawshark species (Pristiophorus cirratus, Pristiophorus nudipinnis) co-occur in waters off east Tasmania, Australia. This study determined the trophic positions of these sawsharks and whether they avoided competing with each other through resource partitioning. Isotopic analysis of muscle tissue revealed that P. cirratus and P. nudipinnis had significantly different trophic levels, with P. cirratus likely to have a diet of primary consumers and P. nudipinnis likely to have a piscivorous diet. Owing to their different isotopic signatures, it is also likely that the sawshark rostrum has multiple functions. Both species shifted to higher trophic levels during ontogeny. Maternal isotopic signatures were detectable in P. cirratus juveniles.

scholarly journals Isotopic signatures induced by upwelling tag regional fish populations in Lake Tanganyika

2021 ◽  
Author(s):  
Benedikt Ehrenfels ◽  
Julian Junker ◽  
Demmy Namutebi ◽  
Cameron M. Callbeck ◽  
Christian Dinkel ◽  
...  
Keyword(s):  
Lake Tanganyika ◽  
Management Strategies ◽  
Pelagic Fish ◽  
Trophic Levels ◽  
Fish Populations ◽  
Isotopic Signatures ◽  
Basin Scale ◽  
Different Seasons ◽  
Fundamental Insight ◽  
Isotopic Variations

Lake Tanganyika's pelagic fish sustain the second largest inland fishery in Africa and are under pressure from heavy fishing and global warming related increases in stratification. Only little is known about whether basin-scale hydrodynamics - including a more stratified north and an upwelling-driven south - lead to regional fish populations with varying ecological adaptations. Here, we examine whether the basin-scale dynamics leave distinct isotopic imprints in the pelagic fish of Lake Tanganyika, which may reveal differences in habitat, diet, or lipid content. We conducted two lake-wide campaigns during different seasons and collected physical, nutrient, chlorophyll, phytoplankton and zooplankton data. Additionally, we analyzed the pelagic fish - the clupeids Stolothrissa tanganicae, Limnothrissa miodon and four Lates species - for their isotopic and elemental carbon (C) and nitrogen (N) compositions. The δ13C values were significantly higher in the productive south after the upwelling/mixing period across all trophic levels, implying that the fish have regional foraging grounds, and thus record these latitudinal isotope gradients. However, the degree of regional isolation is insufficient to suppress lake-wide gene flow, suggesting that the fish form regional populations only on a basin-wide and seasonal scale. Based on δ15N and C:N ratios, we found no strong evidence for varying diets or lipid contents between those populations. Additional analyses revealed that isotopic variations between specimens from the same location are not linked to genetic differences. Our findings provide fundamental insight on the connectivity and ecology of Lake Tanganyika's pelagic fish and imply that sustainable management strategies may adopt basin-scale fishing quotas.

scholarly journals Isotopic analysis in teeth of contemporary brazilians with known diet and geolocation and its forensic value for human identification

2021 ◽  
Vol 10 (12) ◽  
pp. e238101220243
Author(s):  
Rachel Lima Ribeiro Tinoco ◽  
Murilo Quitans Ribeiro Bastos ◽  
Carlos Eduardo Palhares Machado ◽  
Roberto Ventura Santos ◽  
Claudia Rodrigues-Carvalho
Keyword(s):  
Isotopic Ratio ◽  
Geographic Origin ◽  
Human Identification ◽  
Isotopic Analysis ◽  
Trophic Levels ◽  
Isotopic Signatures ◽  
Isotope Data ◽  
Isotopic Analyses ◽  
Modern Population ◽  
Forensic Value

Dental anthropological data may provide valuable information about an individual's life, including age at death, health, signs of violence, ancestry, diet features, intentional modifications, and geographic origin. These pieces of information may be further detailed by diet and residential mobility estimates provided by isotopic analyses. The use of isotope data in the modern population is strongly dependent on the diverse origin of food supply, thus requiring an updated and location-specific database. In this study, we have analyzed the isotopic ratio of strontium, carbon, and nitrogen in enamel and dentin collagen of third molars individuals from three main cities in Brazil. Besides the isotope data, we have also surveyed their diet in adolescence habits to develop models to be applied for forensic studies in the Brazilian territory. We show that the forensic value of the place of origin estimation based 87Sr/86Sr levels is reduced in these highly urbanized samples. Among the outliers, most individuals are older than the mean age (25.1) or had water from wells in childhood. The sample's diet has a robust C4 presence and mean trophic levels consistent with the declared high frequency of chicken, meat, and dairy products, also compatible with the high consumption of sugar, rice, and beans in the local culture. Individuals with special diets, either by choice or therapeutic needs, were potential outliers among the group. Our results also contribute to the international human tissues isotopic database and can contribute for human identification of Brazilians or foreigners with distinct isotopic signatures.

scholarly journals Links between Phenology of Large Phytoplankton and Fisheries in the Northern and Central Red Sea

2021 ◽  
Vol 13 (2) ◽  
pp. 231
Author(s):  
John A. Gittings ◽  
Dionysios. E. Raitsos ◽  
Robert J. W. Brewin ◽  
Ibrahim Hoteit
Keyword(s):  
Red Sea ◽  
Phytoplankton Bloom ◽  
Size Structure ◽  
Management Strategies ◽  
Trophic Levels ◽  
Cell Diameter ◽  
Food Web Structure ◽  
Marine Management ◽  
Fisheries Resources ◽  
Phytoplankton Size

Phytoplankton phenology and size structure are key ecological indicators that influence the survival and recruitment of higher trophic levels, marine food web structure, and biogeochemical cycling. For example, the presence of larger phytoplankton cells supports food chains that ultimately contribute to fisheries resources. Monitoring these indicators can thus provide important information to help understand the response of marine ecosystems to environmental change. In this study, we apply the phytoplankton size model of Gittings et al. (2019b) to 20-years of satellite-derived ocean colour observations in the northern and central Red Sea, and investigate interannual variability in phenology metrics for large phytoplankton (>2 µm in cell diameter). Large phytoplankton consistently bloom in the winter. However, the timing of bloom initiation and termination (in autumn and spring, respectively) varies between years. In the autumn/winter of 2002/2003, we detected a phytoplankton bloom, which initiated ~8 weeks earlier and lasted ~11 weeks longer than average. The event was linked with an eddy dipole in the central Red Sea, which increased nutrient availability and enhanced the growth of large phytoplankton. The earlier timing of food availability directly impacted the recruitment success of higher trophic levels, as represented by the maximum catch of two commercially important fisheries (Sardinella spp. and Teuthida) in the following year. The results of our analysis are essential for understanding trophic linkages between phytoplankton and fisheries and for marine management strategies in the Red Sea.

Nitrogen-stable isotopic signatures of basal food items, primary consumers and omnivores in rivers with different levels of human impact

2008 ◽  
Vol 24 (1) ◽  
pp. 127-136 ◽  
Author(s):  
Ayato Kohzu ◽  
Ichiro Tayasu ◽  
Chikage Yoshimizu ◽  
Atsushi Maruyama ◽  
Yukihiro Kohmatsu ◽  
...  
Keyword(s):  
Human Impact ◽  
Isotopic Signatures ◽  
Food Items ◽  
Stable Isotopic ◽  
Primary Consumers ◽  
Different Levels

scholarly journals Cases of spontaneous interbreeding of wolf and domestic dog in the region of Southeast Banat

2006 ◽  
Vol 58 (4) ◽  
pp. 225-231 ◽  
Author(s):  
M. Milenkovic ◽  
Vesna Habijan-Mikes ◽  
Rada Matic
Keyword(s):  
Genetic Structure ◽  
Management Strategies ◽  
Domestic Dog ◽  
Primary Concern ◽  
Local Process ◽  
Conservation And Management

The study presents the first documented data indicating the occurrence of spontaneous interbreeding of wolf and domestic dog in nature on the territory of Serbia, based on three specimens originating from the region of Southeast Banat. Some unique morpho-anatomical malformations of the cranium in two specimens are described. Based on complex morphological and craniometrical analysis of hybrid specimens and comparison with the corresponding material of authentic wolves from this region, it is possible to follow a local process of multiple wolf/dog hybridization and disturbance of the authentic genetic structure of wolf. The identification of wolf/dog hybrids is a subject of primary concern for the development of conservation and management strategies. Because of great vulnerability of the population of South-Carpathian wolves on the boundaries of their range in Serbia, there is a need for permanent and increased protection in order to maintain their adequately strong population in this region. .

Seven new species of Graphidaceae (Lichenized Ascomycetes) from the Coastal Plain of southeastern North America

Phytotaxa ◽  
2014 ◽  
Vol 189 (1) ◽  
pp. 153 ◽  
Author(s):  
James C. Lendemer ◽  
Richard C. Harris
Keyword(s):  
North Carolina ◽  
New Species ◽  
North America ◽  
Coastal Plain ◽  
Management Strategies ◽  
Lichenized Ascomycetes ◽  
North America North ◽  
Effective Conservation ◽  
Conservation And Management

Seven new species of Graphidaceae are described from the Coastal Plain of southeastern North America: Acanthothecis floridana (Florida, USA), A. leucoxanthoides (North Carolina, USA), A. paucispora (North Carolina, USA), Fissurina alligatorensis (Florida and North Carolina, USA), F. americana (Florida and Georgia, USA), F. ilicicola (Florida and Georgia, USA), and Phaeographis oricola (North Carolina, USA). The ecology and distribution of each species is discussed in the broader context of the imminent need for effective conservation and management strategies to maintain the lichen biodiversity in the region. Color illustrations of all species are provided, as are keys to the genera Acanthothecis and Fissurina in North America north of Mexico.

Roadsides are key habitats for birds in the Argentine Pampas: conservation and management implications

2021 ◽  
pp. 1-6
Author(s):  
Daniela María Depalma ◽  
Mariela Verónica Lacoretz ◽  
Cecilia Zilli ◽  
Emilio Martín Charnelli ◽  
Myriam Emilia Mermoz
Keyword(s):  
Management Strategies ◽  
Tall Grass ◽  
Vegetation Diversity ◽  
Seed Availability ◽  
Bird Richness ◽  
Public Areas ◽  
Declining Species ◽  
Native Birds ◽  
Argentine Pampas ◽  
Conservation And Management

Summary Unexploited public areas such as roadsides could provide habitat to help preserve biodiversity in South America, as in other regions. Our objective was to determine the importance of the roadsides of the Argentine Pampas for native birds and to suggest management strategies. We surveyed birds inhabiting roadsides in all seasons and determined whether roadsides were used as habitat. We recorded a total of 95 species on roadsides, which represents 55% of those species described from the area. Species included specialists of grassland, wetland and woodland, 4 vulnerable species and 19 declining species. Bird richness decreased in winter, as well as grassland specialists’ abundances. Most individuals used roadsides for foraging and performing reproduction-related behaviours, mainly on native trees; these and tall grass were the main substrates. We conclude that many species of birds use the habitat provided by roadsides, and we recommend management strategies such as favouring seed availability in winter, restoring trees and tall grass and increasing vegetation diversity to maximize roadside conservation value.

Black Bass Diversity: Multidisciplinary Science for Conservation

2015 ◽  
Keyword(s):  
Population Dynamics ◽  
Management Strategies ◽  
Smallmouth Bass ◽  
Micropterus Dolomieu ◽  
Spawning Period ◽  
Sampling Gear ◽  
Gray Literature ◽  
Black Bass ◽  
Effective Conservation ◽  
Conservation And Management

<em>Abstract</em>.—We reviewed the published and gray literature associated with Neosho Smallmouth Bass <em>Micropterus dolomieu velox</em> and the genetically distinct Ouachita lineage. Substantial interstream variation appears to occur among these populations, particularly related to age. The Neosho subspecies is more abundant, grows faster, and lives longer than the genetically distinct Ouachita lineage. Recruitment is highly variable among streams for both populations and appears to be related to some undescribed aspects of hydrology but also likely reflect bias due to sampling gear. Information on annual and seasonal trends is lacking for the Neosho subspecies and the Ouachita lineages, particularly as related to the spawning period. Conservation efforts for these lineages might benefit from agencies partnering to achieve goals that extend beyond a particular agency’s responsibilities and state boundaries. Recognition of spatial and temporal considerations, combined with a better understanding of the population dynamics as related to abundance, growth, mortality and reproduction, would benefit the creation of more effective conservation and management strategies for genetically distinct populations of Smallmouth Bass <em>M. dolomieu</em>.

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