The inflow of fresh water into coastal lagoons is a key factor influencing the structure and function of these ecosystems. Biscayne Bay, a coastal lagoon adjacent to the city of Miami, is located downstream of the Everglades ecosystem where the extensive water management system now in place has modified the historical hydrology, replacing groundwater and overland flows with pulsed releases from canals. In areas where canals discharge directly into littoral habitats, an environment with low-mean salinity and high-salinity variability is created. In this study, we characterize the salinity patterns of nearshore habitats (<500 m from shore) and document patterns of seasonal abundance and distribution of submerged aquatic vegetation (SAV) to evaluate the impacts of water management practices. Seagrasses were the principal component of the SAV community during the 2005 dry season (mean cover = 25.5%), while macroalgae dominated during the wet season (mean cover = 33.4%). The distribution and abundance of SAV were directly related to the tolerance of each taxon to salinity patterns. Seagrass species with high tolerance to low and variable salinity such as Halodule wrightii and Ruppia maritima were found only in canal-influenced areas and increased in abundance and spatial distribution in the wet season when freshwater inflow is highest. The dominance of rhizophytic macroalgae during the wet season was determined by the appearance and high abundance of Chara, a taxon commonly associated with freshwater environments. Thalassia testudinum, the most abundant seagrass species, was found throughout the study region, but decreased in abundance in the canalinfluenced areas during the wet season when lower, more variable salinity resulted in lowered productivity. The data presented here showed a significant relationship between salinity patterns and the seasonal abundance and distribution of SAV. These findings support the use of SAV as appropriate indicators of changes in water quality resulting from future restoration projects associated with the Everglades Restoration Plan, which will once again modify the delivery of fresh water into littoral habitats with unknown ecological consequences.Handling editor: S. M. Thomaz

Vessel groundings are a major source of disturbance to coral reefs worldwide. Documenting the extent of damage caused by groundings is a crucial first step in the reef restoration process. Here, we describe the application of a novel survey methodology, landscape video mosaics, to assessment of the damage caused by vessel groundings. Video mosaics, created by merging thousands of video frames, combine quantitative and qualitative aspects of damage assessment and provide a georeferenced, landscape, high‐resolution, spatially accurate permanent record of an injury. The scar in a Florida reef impacted by a 49‐foot vessel, imaged in 2005 and 2006, covered an area of 150 m2 (total imaged area was >600 m2). The impacted coral community showed limited signs of coral recovery more than 3 years after the initial impact; the cover of corals was still significantly higher in the undamaged areas compared to the scar. However, seagrass colonization of the scar was observed. Finally, no evidence of further physical impacts was documented even when four hurricanes passed near the grounding site in 2005. The video mosaics developed in this study proved to be ideal tools to survey the grounding scars. Mosaics provide a means to collect information on the size of the damage area and the status and trends of the impacted biological communities and provide a permanent visual record of the damage, thereby expanding the quality and diversity of information that can be collected during field surveys.

No abstract

No abstract