Microzooplankton mediate a critical juncture of autotrophic and heterotrophic microbial production in the water column. Taxonomic and ecological work on this group has been substantial, yet few reports exist for the offshore waters of the Gulf of Mexico (GOM). This report focuses on protists in the phylum Ciliophora collected at stations spanning the continental shelf in the northeastern GOM. We hypothesized that patterns of spatial distribution across the region would be west–east along the coast, rather than north–south coastal to offshore, reflecting major freshwater sources. Samples were obtained by 10 µm plankton net for microscopy and by filtration of seawater for DNA extraction and ciliate-specific clone sequencing. Microscopy and molecular analysis recovered 46 and 156 taxa, respectively. Some visually identified taxa were missing from the sequence analysis and sequences from unknown species dominated molecular results. Differences were apparent with both dominant and rare taxa between February and July sampling and across a trophic gradient from coastal influenced stations to those more representative of the offshore environment. This report provides new data on ciliate microzooplankton richness and distribution in the GOM and adds to our understanding of microzooplankton diversity in the ocean.
Seagrasses provide ecosystem services such as nursery habitats, refuge, and biogeochemical cycling. However, because seagrass communities are in decline, restoration efforts have increased. The seagrass restoration and monitoring programs at the Florida Department of Environmental Protection (FDEP) transplanted plugs of salvaged seagrasses from dock and marine construction sites. In this study, we used a 2-yr-old FDEP transplant site at Big Lagoon, Pensacola, FL, to compare primary production, respiration, and nutrient fluxes in mixed seagrass beds of Thalassia testudinum (turtle grass) and Halodule beaudettei (shoal grass) with intact, native beds of these seagrasses. We placed light and dark incubation chambers in native and transplanted seagrass beds on 10 different days during the growing season between May and Oct. to measure fluxes of oxygen, nitrate (NO 3 ), dissolved inorganic phosphate (DIP), and ammonium (NH 4 + ). This study found no significant differences in the fluxes of any of the nutrients measured or in the production or respiration rates of native vs transplanted seagrass beds. The most significant environmental factor influencing net community production was light level. Nutrient fluxes were very low and variable, although there were consistent ammonium uptake and nitrate release early in the growing season. This rapid convergence in seagrass function by the transplanted beds to rates similar to those of native beds was likely the result of several factors, including use of plugs for restoration and planting adjacent to existing, healthy beds.
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