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Plants and animals in brackish marshes are adapted to live within a wide, yet finite, range of conditions. Events that shift the environmental state beyond that range can dramatically alter habitats and, potentially, the numerous ecosystem services they provide. A prolonged exceptional drought in Texas (October 2010-January 2012) provided a unique opportunity to understand how brackish wetland habitats respond to an extreme environmental event. We examined marshes in the Lower Neches Wildlife Management Area (Texas, USA) that fell within the drought affected area, including restored areas and an adjacent reference marsh. To test our hypothesis that the brackish marsh community would be sensitive to drought conditions, we quantified emergent plant and submerged aquatic vegetation (SAV) and animal (invertebrates, fish) characteristics in summer 2010 and 2011. In spite of its severity, the exceptional drought of 2011 did not have a negative impact on emergent plant communities: biomass, stem density, and chlorophyll a concentrations were the same in pre-drought and drought years in all restored and reference areas. In contrast, SAV biomass was reduced by up to 100 % in the drought year. Some fish and invertebrate densities were also reduced by an order of magnitude or more, possibly due to the loss of SAV. Aquatic faunal species composition was markedly different in the drought year, largely due to the loss of the hydrobiid snail Probythinella protera and the gain of some marine species, including Gulf menhaden ( Brevoortia patronus), brown shrimp ( Farfantepenaeus aztecus), and white shrimp ( Litopenaeus setiferus). By altering aquatic the plant and animal community, this drought event may subsequently reduce trophic support for higher consumers, or contribute to a decline in water quality. Restoration monitoring programs that only focus on relatively stress-resistant, emergent wetland plant communities may underestimate the sensitivity of these ecosystems to extreme environmental events like droughts. [ABSTRACT FROM AUTHOR]

Abstract: Couplings between land use and marine food webs in tropical systems are poorly understood. We compared land–sea coupling in seven sites around Puerto Rico, differing in the degree of precipitation and urbanization, by measuring δ 13C and δ 15N in producers and consumers. δ 15N values were influenced by human activity: the food web from sites near urbanized centers was on average 1‰ heavier in δ 15N compared to undeveloped sites. This is most likely due to wastewater inputs from septic systems relatively near the shoreline. Changes in δ 13C were best explained by differences in the degree of marine influence. Where terrestrial inputs from a major river dominated, δ 13C values were lighter, whereas sites further from land and in locations exposed to oceanic currents had heavier δ 13C values, characteristic of a marine source of dissolved organic carbon. We found no significant effect of precipitation on connectivity in spite of a twofold difference in annual average rainfall between the north and south coast. The results suggest there is some connectivity between land and sea in Puerto Rico, despite high rates of evaporation relative to precipitation. [Copyright &y& Elsevier]