Why are diverse relationships observed between phytoplankton biomass and transport time?

Lucas, Lisa V.; Thompson, Janet K.; Brown, Larry R.

doi:10.4319/lo.2009.54.1.0381

Cited by 178 publications

(114 citation statements)

References 51 publications

Supporting

Mentioning

106

Contrasting

Unclassified

Order By: Relevance

“…In the absence of freshwater inflow, the flushing time of the SLE is approximately 20 d solely through tidal exchange (Y. Wan and D. Sun, unpublished data). Nutrient budget results suggested that both the concentrations and internal utilization of DIP and DIN stabilized with flushing times greater than 10 d. Longer water residence times allow for increased grazing and sedimentation to respond to primary production and balance system metabolism (Buzzelli et al, 2007;Lucas et al, 2009;Phlips et al, 2011;Swaney et al, 2011). In fact, it appears that the negative relationship between flushing time and NEM observed in this study is a common attribute of many estuaries (Fig.…”

Section: Discussionmentioning

confidence: 71%

Seasonal dissolved inorganic nitrogen and phosphorus budgets for two sub-tropical estuaries in south Florida, USA

et al. 2013

View full text Add to dashboard Cite

Abstract. Interactions among geomorphology, circulation, and biogeochemical cycling determine estuary responses to external nutrient loading. In order to better manage watershed nutrient inputs, the goal of this study was to develop seasonal dissolved inorganic nitrogen (DIN) and phosphorus (DIP) budgets for the two estuaries in south Florida, the Caloosahatchee River estuary (CRE) and the St. Lucie Estuary (SLE), from 2002 to 2008. The Land-Ocean Interactions in the Coastal Zone (LOICZ) approach was used to generate water, salt, and DIN and DIP budgets. Results suggested that internal DIN production increases with increased DIN loading to the CRE in the wet season. There were hydrodynamic effects as water column concentrations and ecosystem nutrient processing stabilized in both estuaries as flushing time increased to > 10 d. The CRE demonstrated heterotrophy (net ecosystem metabolism or NEM < 0.0) across all wet and dry season budgets. While the SLE was sensitive to DIN loading, system autotrophy (NEM > 0.0) increased significantly with external DIP loading. This included DIP consumption and a bloom of a cyanobacterium (Microcystis aeruginosa) following hurricane-induced discharge to the SLE in 2005. Additionally, while denitrification provided a microbiallymediated N loss pathway for the CRE, this potential was not evident for the SLE where N 2 fixation was favored. Disparities between total and inorganic loading ratios suggested that the role of dissolved organic nitrogen (DON) should be assessed for both estuaries. Nutrient budgets indicated that net internal production or consumption of DIN and DIP fluctuated with inter-and intra-annual variations in freshwater inflow, hydrodynamic flushing, and primary production. The results of this study should be included in watershed management plans in order to maintain favorable conditions of external loading relative to internal material cycling in both dry and wet seasons.

show abstract

Section: Discussionmentioning

confidence: 71%

Seasonal dissolved inorganic nitrogen and phosphorus budgets for two sub-tropical estuaries in south Florida, USA

et al. 2013

View full text Add to dashboard Cite

show abstract

“…It has been shown with a simple model of a vertically homogeneous advective system that if growth is faster than losses, phytoplankton biomass will indeed increase with time spent in the system (as is commonly expected); on the other hand, if losses dominate over growth, phytoplankton biomass will decrease with time spent in the system (Lucas et al 2009b). That model (which previously only calculated biomass concentration exiting the habitat) is extended herein to calculate habitat averaged biomass and net primary productivity.…”

Section: Model Testing Of Hypothesismentioning

confidence: 99%

“…The objective was to explore the relationship between phytoplankton and the time it spends in a habitat, and how that relationship is affected by benthic grazing rate. Thus, the role of s tran here is to characterize the time for a water parcel to travel through a defined habitat, from inlet to exit (i.e., a ''transit time''); this quantity thus represents the time phytoplankton within the parcel are exposed to growth-loss conditions within the habitat (Lucas et al 2009b). (See Lucas [2010] for discussion of how ''transit time'' is related to commonly referenced terms such as ''flushing time'' and ''residence time.'')…”

Section: General Model Description and Strategymentioning

confidence: 99%

Changing restoration rules: Exotic bivalves interact with residence time and depth to control phytoplankton productivity

Lucas

Thompson

2012

Ecosphere

Self Cite

View full text Add to dashboard Cite

Citation: Lucas, L. V., and J. K. Thompson. 2012. Changing restoration rules: Exotic bivalves interact with residence time and depth to control phytoplankton productivity. Ecosphere 3(12):117. http://dx.doi.org/10.1890/ES12-00251.1Abstract. Non-native species are a prevalent ecosystem stressor that can interact with other stressors to confound resource management and restoration. We examine how interactions between physical habitat attributes and a particular category of non-native species (invasive bivalves) influence primary production in aquatic ecosystems. Using mathematical models, we show how intuitive relationships between phytoplankton productivity and controllable physical factors (water depth, hydraulic transport time) that hold in the absence of bivalves can be complicated-and even reversed-by rapid bivalve grazing. In lightlimited environments without bivalves, shallow, hydrodynamically ''slow'' habitats should generally have greater phytoplankton biomass and productivity than deeper, ''faster'' habitats. But shallower, slower environments can be less productive than deeper, faster ones if benthic grazing is strong. Moreover, shallower and slower waters exhibit a particularly broad range of possible productivity outcomes that can depend on whether bivalves are present. Since it is difficult to predict the response of non-native bivalves to habitat restoration, outcomes for new shallow, slow environments can be highly uncertain. Habitat depth and transport time should therefore not be used as indicators of phytoplankton biomass and production where bivalve colonization is possible. This study provides for ecosystem management a particular example of a broad lesson: abiotic ecosystem stressors should be managed with explicit consideration of interactions with other major (including biotic) stressors. We discuss the applicability and management implications of our models and results for a range of aquatic system types, with a case study focused on the Sacramento-San Joaquin Delta (California, USA). Simple mathematical models like those used here can illuminate interactions between ecosystem stressors and provide process-based guidance for resource managers as they develop strategies to augment valued populations, restore habitats, and manipulate ecosystem functions.

show abstract

“…First, residence time of water and associated phytoplankton and zooplankton communities can increase within the upper portion of estuaries, facilitating the accumulation of biomass within this region (Lucas et al 2009). Second, smaller order tidal freshwater river channels are characterized by much greater water column irradiance than the non-tidal channels upstream, allowing for pulses of phytoplankton biomass to develop (Ensign et al 2012).…”

Section: Indirect Effects Of Planktivorous Fish On Phytoplankton Biomassmentioning

confidence: 99%

Effects of nutrients and zooplankton on an estuary's phytoplankton: inferences from a synthesis of 30 years of data

Ensign¹,

Leech²,

Piehler³

2014

Ecosphere

View full text Add to dashboard Cite

Abstract. Phytoplankton biomass is commonly used as a water quality metric in the management of anthropogenic nitrogen and phosphorus loading, yet interpretation of the long-term response of phytoplankton biomass to nutrient regulation may be confounded by changes in zooplankton grazing pressure. Zooplankton community structure may be affected by planktivorous fish whose populations are subject to losses through fishing and gains through restoration efforts. We investigated temporal changes in phytoplankton biomass, nitrogen and phosphorus concentrations, zooplankton, and planktivorous fish in the tidal fresh and oligohaline Chowan River, NC, over a 30-year period in order to compare long-term trends in these parameters and infer their relative influence on phytoplankton biomass. Data were compiled from the records of two state agencies and several academic studies and supplemented by our own two year monitoring of water quality and zooplankton in the Chowan River mainstem and two tributaries. Seasonal trend decomposition using locally weighted regression was applied to chlorophyll a (a proxy for phytoplankton biomass), nitrogen, and phosphorus, and showed that chlorophyll a declined more quickly than did nutrient concentrations over the 30-year period. Despite the long-term decline in nitrogen and to a lesser extent phosphorus, the long-term trend in phytoplankton growth rate (predicted using an empirical model involving irradiance and nutrients) remained relatively constant. Zooplankton abundance increased from the period 1981-1982 to 2008-2010, as did the predicted zooplankton community water clearance rate (a proxy for zooplankton grazing). River herring, historically the dominant planktivore, declined dramatically over the 30-year period. The data indicate that the most parsimonious explanation for the long term decrease in chlorophyll a is an increase in zooplankton and not a decrease in nutrients. This inference leads us to hypothesize that the historically large river herring population exerted a positive, indirect influence on phytoplankton biomass in the Chowan River system, and that the decline in river herring has lead to higher zooplankton abundance and subsequently lower phytoplankton biomass.

show abstract

Why are diverse relationships observed between phytoplankton biomass and transport time?

Cited by 178 publications

References 51 publications

Seasonal dissolved inorganic nitrogen and phosphorus budgets for two sub-tropical estuaries in south Florida, USA

Seasonal dissolved inorganic nitrogen and phosphorus budgets for two sub-tropical estuaries in south Florida, USA

Changing restoration rules: Exotic bivalves interact with residence time and depth to control phytoplankton productivity

Effects of nutrients and zooplankton on an estuary's phytoplankton: inferences from a synthesis of 30 years of data

Contact Info

Product

Resources

About