No abstract

Catfishes of the Family Ariidae are characterized as eurythermal and euryhallne inhabitants of estuarine waters. In the Southern Gulf of Mexico (Terminos Lagoon) there are 3 species: Arius felis, A. melanopus, and Bagre rnarinus. Juveniles of A. melanopus occur in the fluvial-lagoon system (FLS) in areas with oysters Crassostrea virginica, while adults occur throughout the lagoon. A.melanopusreaches sexual maturity at 160 mm total length (TL) and reproduces in FLS in salinities < 12 ppt, temperatures 2 35 "C and high turbidity waters. Males of 160 to 222 mm TL with eggs and/or embryos in their mouths are abundant in August and September, after which they migrate towards areas of greater salinity, lower temperature and less turbidity Juveniles recruit towards the western inlet (estuarine) and central basin of the lagoon. The reproduclve pattern of A. felis is the inverse of A. melanopus. Juveniles are found in areas of hgher salinity in the lagoon, and adults occur throughout the lagoon. The species matures sexually after reaching 200 mm TL and reproduces in salinities > 12 ppt, temperatures 2 30 "C, and in less turbid areas dominated by Thalassia testudi~~um meadows. Males with eggs and/or embryos in their mouths are found In September. After the incubation period adults migrate toward the eastern inlet (marine) and luveniles toward the western inlet (estuarine). B. marjnus is found only in the western inlet (estuarine), central basin, and FLS of Terminos Lagoon. This specles reproduces along the coastline and enters the lagoon at the end of the rainy and winter storm or nortes season. Juveniles use the lagoon as nursery area. The Terminos Lagoon has a high diversity of habitats due to ecological interchange with rivers, swamps and the inner shelf. Three main strategies in the use of the system by catfishes in relation to reproduction and feeding may be characterized as: (1) spawning in the rivers and swamps followed by a migration of juveniles toward the central part of the estuarine system; (2) spawning in the estuarine system; and (3) s p a w~n g in the sea followed by migration of juveniles to the FLS for feeding. Estuarine fish that have separate reproduction, growth, and feeding areas generally occur in great abundance and have adapted by reducing interspecific competition and temporal and spatial niche partition. In tropical high diversity ecosystems, biological cycles are closely related to high productivity of coastal waters, large supply of organic matter, increased food availability, and protection from predators. The estuary-inner shelf or swamp-estuary migrations can be interpreted as small-scale anadromous adaptations.

No abstract

In Terminos Lagoon, M6xico, more than 80 fish species use the mangrove and seagrass habitats. We studied nekton dynamics in an inlet seagrass system and a more sheltered seagrass/mangrove system located behind a barrier island. Seasonal community biomass ranges from 0.6 to 5.2 g wet wt m-2. For the two habitats together, there are 28 dominant species. Eleven species were common to both areas:Valenciennes, 1830), Cichlasoma urophtalmus (Guinther, 1862) and Acanthostracion quadricornis (Linnaeus, 1758). Comparative analysis showed that periodic variation in biomass and diversity of fish assemblages in seagrass and seagrass/mangrove habitats were synchronized with sizes and densities of population, season of the year (dry, wet, 'nortes'), circulation pattern, and patterns of primary production (phytoplankton, Thalassia testudinum Konig, 1805; and Rhizophora mangle Linnaeus). This analysis allowed the definition of 3 life-cycle patterns with a clear nektonic 'seasonal programming' following the timing of primary production in these critical habitats: (1) marine species which spawn in or near the inlet with eggs and larvae transported into and distributed throughout the lagoon by the predominant *EPOMEX Program Contribution No. 0026. 2 currents; (2) estuarine-marine species which spawn in different habitats of the lagoon and use the seagrass/mangrove system as a nursery area, and (3) species which complete their life history in the inlet seagrass and/or seagrass/mangrove systems.

Nekton dynamics were studied in two contrasting habitats in Terminos Lagoon, Mexico. Over an annual cycle, a total of 83 fish species used the high-salinity fringing mangrove/Tha/assiu resfudinum habitat and biomass ranged from 0.43 to 3.43 g m-z. The highest biomass occurred during the dry season when aquatic primary production was highest (i.e. 333 g C m-z year-'). By contrast, 65 species used the freshwater and low-salinity riverine mangrove/Crassostreu virginicu/Vu/lisneriu habitat and biomass ranged from 0.57 to 1.48g m2 with the highest biomass occurring during the wet season, the time of highest primary production in this habitat (i.e. 219 g C m-* yea-'). The high-and low-salinity habitats serve as ecological bridges between freshwater areas and the sea. Fish life histories have evolved to utilize these habitats for spawning, feeding and nursery grounds in a manner which generally leads to the use of different habitats during the periods of highest primary productivity.

Los manglares constituyen un importante recurso forestal en toda la banda intertropical del planeta. Las acciones antrópicas acrecientan los riesgos sobre los ecosistemas y esto ha sido más catastrófico que el propio cambio climático global. Este último induce nuevas incertidumbres en la estabilidad ambiental y aumenta la vulnerabilidad de los hábitats críticos. Frente al desafío que enfrentan los sistemas económicos, sociales y ecológicos se presentan evidencias de estructura funcional de este sistema ecológico, planteando la hipótesis que “los manglares como hábitat forestado crítico de la zona costera presentan respuestas de acomodación frente a la variabilidad ambiental que induce el cambio global, desarrollando un papel estructural y funcional clave en la estabilidad de la línea de costa, la persistencia de hábitats y biodiversidad, el metabolismo del ecosistema, reduciendo riesgos e incertidumbre para el desarrollo sustentable del uso de sus recursos”.

No abstract

Crown displacement in trees is an adaptive response driven by neighbours that optimizes space use and reduces competition. But it can also be the result of wind force. Although morphological responses to neighbours have been well studied, the interplay between neighbours and wind in driving crown shape, and the implications for plant interactions remain poorly understood. However, it is crucial to predict such changes in vegetation structure and function under the scope of global change. We test the hypothesis that aboveground interactions are reduced with increasing soil stress and that wind becomes the main driver of crown shape in mangrove forests. We investigated the effect of neighbours and wind intensity and direction on crown displacement of mangrove canopy and below canopy trees along a salinity gradient, and assessed crown asymmetry for three mangrove tree species, as well as the contribution of crown displacement on reducing crown‐projected area overlap and thus neighbourhood competition. Results show that crown displacement of canopy trees is strongly influenced by winds at all salinities. At low salinities, competition for space accounted for 48% of crown displacement away from neighbours, compared to 49% found for the synthetized effects of wind and neighbours. While trees below the canopy displace their crowns away from their neighbours, no response to wind could be detected. This can be due to the wind protection conferred by a dense canopy stand related to bigger crowns that effectively reduce wind drag. At higher salinities, there was a reduction in canopy overlap due to crown displacement, which suggests reduced aboveground plant interactions with increasing soil stress. While neighbourhood avoidance is a fundamental strategy for optimal light foraging, this study shows that wind strength and directionality are main drivers of crown shape with increasing stress and highlights their potential influence in plant interactions and forest structure, pointing to an increased susceptibility of trees to disturbances that should be further studied. A http://onlinelibrary.wiley.com/doi/10.1111/1365-2435.13218/suppinfo is available for this article.