Trophic niche of the Pacific Sierra (Scomberomorus sierra) in the southeastern Gulf of California: Assessing its importance as a predator and prey (Mesopredator) in the food web

The identification of interspecific links (trophic niche) is important to characterize resource use of a predator, and to know its trophic role (for example, mesopredator or top predator) in the food web. In this study, we examined: a) the trophic ecology of Scomberomorus sierra as a predator (niche breadth, trophic overlap, and trophic position) and b) its presence as a prey in the diets of the region´s top predators, to evaluate the critical link of S. sierra as a probable mesopredator in the food web of the southeastern Gulf of California (GC). Based on %PSIRI, the dominant diet of S. sierra were engraulids and cephalopods. The diet was similar between sexes and among size-classes. However, the isotopic niche breadth values and δ¹⁵N variance (>1) reflect a broad niche for young adults likely related to a) changes in morphology (e.g., size of the mouth), b) development of the visual system, and c) changes in the energy requirements of the species reproductive stages. Seasonal changes in prey species’ availability and abundance resulted in isotopic variations, indicating that S. sierra is an opportunistic predator. A wide range in trophic position value (from 3.8 to 4.2) indicated that it also is an intermediary carnivore, with a high degree of trophic plasticity. Although S. sierra has not a dominant role in top predators’ diets, they share some prey species such as anchovies and other fish, depending on predator size. Therefore, S. sierra is a species with many prey-predator relationships in the southeastern GC food webs that may be considered a critical trophic link. This information is crucial for an ecosystem-based fisheries management in the Gulf of California.     

Current status and potential contributions of fisheries statistics from artisanal fisheries for managing juvenile istiophorid billfishes in Southern Brazil

Environmental Biology of Fishes - Billfishes are considered important fishery resources and the identification of aggregation sites is imperative for proper management. Here we present evidence of...     

Hybrid status of kuwini,Mangifera odorata Griff. (Anacardiaceae) verified by amplified fragment length polymorphism

Mangifera odorata Griff. (Anacardiaceae), was suggested to be a hybrid between M. indica L. and M. foetida Lour. due to morphological intermediacy. Results from this study show that M. indica and M. foetida produced unique amplified fragment length polymorphism (AFLP) profiles. Mangifera odorata did not produce any unique bands. All the M. odorata samples additively inherit bands specific to M. indica and M. foetida, which strongly suggested the hybrid origin. Three major clusters were produced in the phenogram. All samples of M. indica, M. foetida and M. odorata segregated distinctly. Mangifera odorata was closer to M. foetida than to M. indica, indicating that backcrossing with M. foetida might have taken place. AFLP analysis therefore verified the hybrid status of M. odorata.