Concerns about global climate change have heightened awareness of the role changing rainfall regimes play in altering plankton communities of coastal ecosystems. In this study spatial and temporal patterns of phytoplankton composition and biomass in a sub-tropical tidal creek in Florida were observed over three wet and dry seasons, which included the major storm year of 2005 and the drought year of 2006. Shifts in rainfall levels were associated with changes in phytoplankton composition and biomass, but the effects varied between the upper and lower reaches of the creek. The upper reach of the creek was fresh throughout the study period. The oligohaline to mesohaline lower creek alternated between fresh and marine species in response to shifts in salinity regimes. Blooms of the freshwater dinoflagellate Peridinium sp., small centric diatoms and nitrogen-fixing cyanobacteria were common in the upper Ten Mile Creek during low rainfall years. The euryhaline marine dinoflagellate Akashiwo sanguinea and centric diatoms (e.g. Leptocylindrus minimus) were observed at bloom levels in the lower creek during low to average rainfall periods. The results are discussed within the context of how variability in rainfall influence water residence times, nutrient concentrations and salinity regimes, which in turn influence phytoplankton composition and biomass.

Oyster populations in south Florida estuaries have declined in part through altered salinity driven by anthropogenic changes in freshwater inputs. In particular, the St. Lucie Estuary (SLE) in southeastern Florida has suffered widespread loss of oyster habitat. With efforts underway to improve water quality and oyster habitat in the SLE, the goal of this study was to develop a model to assess ecosystem level impacts of oyster restoration. Phytoplankton and oyster biomass modeling targets were established from observational data collected from 2005 to 2009. Modeled oyster biomass production and filtration fluctuated with temperature, salinity, and total suspended solids from a combination of observational and predicted input functions in 10-year simulations (1998–2007). Model estimates of oyster biomass fluctuated with salinity from near zero after extreme freshwater discharge in 2002–2003 and 2004–2005 to maximum values near 150.0 and 200.0 g C m−2 in spring 1999 and fall 2006. There was potential for algal blooms as turnover time for the phytoplankton standing stock (15.6 days) was faster than water mass turnover (21.0 days). While >1,000 days were required for 50 ha of oyster habitat to filter the entire volume of the estuarine segment, filter time reduced to <20 days with an estimated fivefold increase in net consumption of phytoplankton if the oyster habitat was increased to 300 ha. Re-establishment of biologically desirable salinity envelopes would stabilize oyster survival allowing the possibility for successful habitat restoration to benefit water quality and faunal attributes of the St. Lucie Estuary.

The St. Lucie Estuary, located on the southeast coast of Florida, provides an example of a subtropical ecosystem where seasonal changes in temperature are modest, but summer storms alter rainfall regimes and external inputs to the estuary from the watershed and Atlantic Ocean. The focus of this study was the response of the phytoplankton community to spatial and temporal shifts in salinity, nutrient concentration, watershed discharges, and water residence times, within the context of temporal patterns in rainfall. From a temporal perspective, both drought and flood conditions negatively impacted phytoplankton biomass potential. Prolonged drought periods were associated with reduced nutrient loads and phytoplankton inputs from the watershed and increased influence of water exchange with the Atlantic Ocean, all of which restrict biomass potential. Conversely, under flood conditions, nutrient loads were elevated, but high freshwater flushing rates in the estuary diminished water residence times and increase salinity variation, thereby restricting the buildup of phytoplankton biomass. An exception to the latter pattern was a large incursion of a cyanobacteria bloom from Lake Okeechobee via the St. Lucie Canal observed in the summer of 2005. From a spatial perspective, regional differences in water residence times, sources of watershed inputs, and the proximity to the Atlantic Ocean influenced the composition and biomass of the phytoplankton community. Long water residence times in the North Fork region of the St. Lucie Estuary provided an environment conducive to the development of blooms of autochthonous origin. Conversely, shorter residence times in the mid-estuary limit autochthonous increases in biomass, but allochthonous sources of biomass can result in bloom concentrations of phytoplankton.

If you enjoyed reading Fundamentals of Aquaculture by James W. Avault, published in 1996, you will find this book to be an informative update on the evolving science of aquaculture best management practices. Covered BMPs are consistent with most regulatory requirements. The first five chapters of Environmental Best Management Practices for Aquaculture emphasize the evolving science by differentiating between “best “and “better” management practices. These chapters illustrate that management practices will continue to improve and regulatory agencies should provide an environment that promotes innovative improvements and experimentation to reduce the potential environmental impacts and increase the sustainability of an aquaculture operation while potentially increasing profits. This can be accomplished through constructive relationships among regulators, academia, and the aquaculture business community. This is good advice for promoting scientifically based BMPs for lake management as well. As a student of consensus development among parties for nonpoint source BMP implementation, I appreciate and agree with the approach described.

Species of submerged aquatic vegetation (SAV) are frequently used in the management of estuarine systems to set restoration goals, nutrient load reduction goals, and water quality targets. As human need for water increases, the amount of freshwater required by estuaries has become an increasingly important issue. While the, science of establishing the freshwater needs of estuaries is not well developed, recent attempts have emphasized the freshwater requirements of fisheries. We evaluate the hypothesis that SAV can be used to establish freshwater inflow needs. Salinity tolerance data from laboratory and field studies of SAV in the Caloosahatchee estuary, Florida, are used to estimate a minimum flow required to maintain the salt-tolerant freshwater species, Vallisneria americana , at the head of the estuary and a maximum flow required to prevent mortality, of the marine species Halodule wrightii at its mouth. For V. americana , laboratory experiments showed that little or no growth occurred between 10‰ and 15‰ In the field, lower shoot densities (<400 shoots m −2 ) were associated with salinities greater than 10‰. Results for H. wrightii were more variable than for V. americana . Laboratory experiments indicated that mortality could occur at salinities <6‰, with little growth occurring between 6‰ and 12‰. Field data indicated that higher blade densities (>600 blades m −2 ) tend to occur at salinities greater than 12‰ Relationships between salinity in the estuary and discharge from the Caloosahatchee River indicated that flows>8.5 m 3 s −1 would produce tolerable salinity (<10‰) for V. americana and flows<89 m 3 s −1 would avoid lethal salinities (<6‰) for H. wrightii .