Lower Suwannee River Research Articles

Poleward expansion of common snook Centropomus undecimalis in the northeastern Gulf of Mexico and future research needs.

Globally, rising temperatures have resulted in numerous examples of poleward shifts in species distribution patterns with accompanying changes in community structure and ecosystem processes. In the Gulf of Mexico, higher mean temperatures and less frequent winter freezes have led to the expansion of tropics-associated marine organisms. Our objectives were to quantify changing environmental conditions and the poleward expansion of the common snook Centropomus undecimalis into the Cedar Keys area of Florida, USA (29 deg N). The snook is an economically and recreationally important sport fish found from southern Brazil to south Florida. Cedar Key and the Lower Suwannee River are north of the snook’s historically documented range, likely due to lethal water temperatures during winter. Using data from a long-term monitoring program, we report an increase in catches of snook in this area since 2007. The spatial and temporal expansion of the species began with adult fish in 2007. By 2018, snook of all sizes were found in the region, and we found strong evidence of local reproduction during 2016–2018. The locations of nursery habitat and winter thermal refuges (e.g., freshwater springs) need to be identified and have implications for land-use policy and minimum-flow regulations for rivers. The arrival of the snook in the northern Gulf of Mexico could affect food web ecology and habitat interactions among estuarine predators, and future studies should evaluate snook’s food habits and competitive interactions with resident fishes in this expanded range. Our study provides an example of how species range expansions due to changing temperatures should result in new research priorities to evaluate impacts of climate change on coastal systems.

Stewardship Ecosystem Services Study Series: Assessing Forest Water Yield and Purification Ecosystem Services in the Lower Suwannee River Watershed, Florida

Land-use decisions and ecosystem characteristics affect the amounts of nutrients that end up in water bodies and the ability of the land to provide ecosystem services. Water quality is also highly valued by Florida forest landowners and managers. So, understanding the role of land use and forest cover and types, management practices, and conservation programs in reducing nutrient pollution will allow landowners, forest managers, and policy makers to make informed and better management decisions. In this 6-page fact sheet, we present the results of a study that used easily available models and information to assess the role of forests in providing ecosystem services, including water quality improvement or purification. Specifically, this assessment used available geospatial data and the InVEST Water Purification model to estimate how forest vegetation and soils purify water through the retention, and subsequent export, of nitrogen and phosphorus polluted runoff. Written by Sonia Delphin, Francisco J. Escobedo, Amr Abd-Elrahman, Alison E. Adams, Jackie Martin, Ronald Cademus, and published by the UF Department of School of Forest Resources and Conservation, January 2014.
 FOR317/FR385: Stewardship Ecosystem Services Study Series: Assessing Forest Water Yield and Regulation Ecosystem Services in the Lower Suwannee River Watershed, Florida (ufl.edu)

Mapping potential carbon and timber losses from hurricanes using a decision tree and ecosystem services driver model

Information on the effect of direct drivers such as hurricanes on ecosystem services is relevant to landowners and policy makers due to predicted effects from climate change. We identified forest damage risk zones due to hurricanes and estimated the potential loss of 2 key ecosystem services: aboveground carbon storage and timber volume. Using land cover, plot-level forest inventory data, the Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) model, and a decision tree-based framework; we determined potential damage to subtropical forests from hurricanes in the Lower Suwannee River (LS) and Pensacola Bay (PB) watersheds in Florida, US. We used biophysical factors identified in previous studies as being influential in forest damage in our decision tree and hurricane wind risk maps. Results show that 31% and 0.5% of the total aboveground carbon storage in the LS and PB, respectively was located in high forest damage risk (HR) zones. Overall 15% and 0.7% of the total timber net volume in the LS and PB, respectively, was in HR zones. This model can also be used for identifying timber salvage areas, developing ecosystem service provision and management scenarios, and assessing the effect of other drivers on ecosystem services and goods.

Broiler Litter vs. Ammonium Nitrate as Nitrogen Source for Bermudagrass Hay Production: Yield, Nutritive Value, and Nitrate Leaching

ABSTRACTThe Lower Suwannee River Basin (LSRB) in northern Florida is environmentally sensitive. This study evaluated two surface‐applied N sources for ‘Tifton 85’ bermudagrass (Cynodon spp.) hay production and associated risk of nitrate contamination of groundwater. The study was conducted at two locations in the LSRB where soils are deep, sandy Entisols. During a 2.5‐yr period, bermudagrass received sole N source ammonium nitrate (AN), applied at 42, 84, 126, and 168 kg N ha−1 per growth interval, or sole N source broiler (chicken, Gallus gallus domesticus) litter (BL), applied at 84 and 126 kg N ha−1 Plots were arranged using a randomized block design with three or four replications depending on the location. Suction‐cup lysimeters were installed at a 1.4‐m soil depth to monitor nitrate movement from the primary rooting zone. For AN, dry matter yield and crude protein (CP) concentration increased with an increase in N level, while forage P declined and in vitro digestible organic matter increased. Forage yield with BL was 64, 48, and 67% of yield with AN applied at common levels in 1998, 1999, and 2000, respectively. Forage CP was mostly less for BL than for AN, but forage P was greater for BL. A potential risk to groundwater quality due to nitrate leaching below the primary rooting zone was observed only with AN applied at 168 kg N ha−1 Probable ammonia emissions from surface‐applied BL, however, likely resulted in poorer bermudagrass production and could impact nearby surface waters.

Relative Abundance, Growth, and Mortality of Five Age‐0 Estuarine Fishes in Relation to Discharge of the Suwannee River, Florida

AbstractUnderstanding the relationships between river discharge and recruitment of estuarine fishes is important because of hydrological alterations caused by anthropogenic water withdrawals. Varying river discharge alters salinity, turbidity, nutrient levels, and detrital concentrations, all of which affect estuarine biota. The lower Suwannee River, Florida, is one of the few remaining large‐river systems in the United States that has no major impoundments. We assessed the relationship between seasonal river discharge and relative abundance, growth, and mortality of estuary‐dependent age‐0 fish of five species in the Suwannee River estuary. We analyzed 9 years of data (1997–2005) collected as part of a long‐term, fishery‐independent monitoring program. The results showed a positive relationship between relative abundance and river discharge for age‐0 spotted seatrout Cynoscion nebulosus, sand seatrout C. arenarius, and red drum Sciaenops ocellatus. The pinfish Lagodon rhomboides was the only species for which relative abundance was negatively related to river discharge; the relative abundance of spot Leiostomus xanthurus was not significantly related to changes in discharge. Instantaneous daily growth (G) estimates were positively related to river discharge for all species except spotted seatrout, for which a negative correlation was found. Instantaneous daily mortality (Z) estimates were positively correlated with river discharge for sand seatrout, pinfish, and red drum. The G: Z ratios for pinfish and early recruiting sand seatrout were negatively related to river discharge, indicating that recruitment potential declined with higher discharge. Changes in freshwater discharge affected the abundance, growth, and survival of these juvenile fishes, stressing the importance of water allocation decisions that affect estuarine fishes and the fisheries they support.

Characterizing Agriculture in Florida’s Lower Suwannee River Basin Area

The Suwannee River Partnership (http://www.suwannee.org) was formed in 1999 to determine the sources of nutrient loads in the river basin, and to work with local land users to minimize future nutrient loading through voluntary, incentive-based programs. Agriculture and forestry are the dominant land uses in the watershed. While the environmental impact of forestry is usually low, intensive agricultural production has the potential to affect water quality if nutrients and water are not carefully managed. This document is SL 241, a fact sheet of the Soil and Water Science Department, UF/IFAS Extension. Original publication date May 2006.

Post-Miocene subtropical karst evolution, lower Suwannee River basin, Florida

Morphometric characteristics of ∼25 000 karstic depressions suggest that the last phase of the post-Miocene karstic evolution within the lower Suwannee River basin of Florida has been controlled by the lower sea-level stands of the Pleistocene and the formation of the Suwannee River. During the Pleistocene, as interglacial seas retreated, marine terraces formed by sequential sea-level lowstands and the time period of subaerial exposure diminished toward the sea. Consequently, geomorphologically younger karst landforms formed as the elevation of marine terraces decreased. The evolutionary geomorphological development of this heavily karstified region produced more frequent and/or larger and more complex depressions at higher elevations. A geographic information system analysis of morphometric and spatial distribution parameters of the karstic depressions within the lower Suwannee River basin reveals that the Florida karst is represented by broad, shallow depressions with an average density of 6.07/km 2 and an average pitting index of 14.5. Morphometric and spatial distribution parameters of karstic depressions show a great variation within the lower Suwannee River area and thus preclude a simple morphoclimatic classification of karst landforms. The Tertiary carbonate rocks of the subtropical Florida karst have relatively less joint frequency and significant primary porosity, and do not produce the extreme karst landforms observed in the massive limestones of the tropics.

Hydrochemical evidence for mixing of river water and groundwater during high-flow conditions, lower Suwannee River basin, Florida, USA

Karstic aquifers are highly susceptible to rapid infiltration of river water, particularly during periods of high flow. Following a period of sustained rainfall in the Suwannee River basin, Florida, USA, the stage of the Suwannee River rose from 3.0 to 5.88 m above mean sea level in April 1996 and discharge peaked at 360 m 3 /s. During these high-flow conditions, water from the Suwannee River migrated directly into the karstic Upper Floridan aquifer, the main source of water supply for the area. Changes in the chemical composition of groundwater were quantified using naturally occurring geochemical tracers and mass- balance modeling techniques. Mixing of river water with groundwater was indicated by a decrease in the concentrations of calcium, silica, and 222 Rn; and by an increase in dissolved organic carbon (DOC), tannic acid, and chloride, compared to low-flow conditions in water from a nearby monitoring well, Wingate Sink, and Little River Springs. The proportion (fraction) of river water in groundwater ranged from 0.13 to 0.65 at Wingate Sink and from 0.5 to 0.99 at well W-17258, based on binary mixing models using various tracers. The effectiveness of a natural tracer in quantifying mixing of river water and groundwater was related to differences in tracer concentration of the two end members and how conservatively the tracer reacted in the mixed water. Solutes with similar concentrations in the two end-member waters (Na, Mg, K, Cl, SO4, SiO2) were not as effective tracers for quantifying mixing of river water and groundwater as those with larger differ- ences in end-member concentrations (Ca, tannic acid,

A survey of benthic invertebrates in the Suwannee River, Florida

Benthic invertebrate communities were surveyed in a 233 km reach of the middle and lower Suwannee River in Northwestern Florida in the winter 1987 and early summer 1988 to determine their abundance and distribution as potential foods of the Gulf sturgeon, Acipenser oxyrhynchus desotoi, and to determine the effects of possible natural and human-induced disturbances to the communities. In substrates of the tidal oligohaline to mesohaline lower reach of the East Pass site I (km 2) and site II West Pass (km 5) near the Gulf of Mexico, densities of tube dwelling and free swimming amphipods, polychaetes, oligochaetes, and dipterans in the PONAR grabs were moderate (100-999 {iex} individuals/m(2)) to abundant (1000-9999 {iex} individuals m(-2)). Also, at sites I and II, low (10-99 {iex} individuals m(-2)) to moderate densities of dipteran Chironomidae and olive nerite snail were collected in hardboard multiplate artificial substrate samplers. Diversities of benthic invertebrates in both grabs and hardboard multiplates were relatively low. Baetid mayflies were moderately abundant in the dip net samples. Upriver from sites I and II, the transition of an oligohaline tolerant benthic community to a freshwater one was abrupt due to strong freshwater flow. At sites III (km 48) and IV (km 89), benthic invertebrate populations were low to moderate in hardboard multiplate and dip net samples. In the middle reach (km 101 to km 233), aquatic insects were predominant and included; chironomids, mayflies, and beetles, and also, freshwater gammarid amphipods, gastropods, and the Asian clam. In winter, the bottom substrates at sites VII (km 153) and VIII (km 205) contained diverse and dense populations of Chironomidae (5932 m(-2)), the greatest density for a major taxonomic group recorded in this survey. Crayfish were collected in low densities only in artificial substrate samplers from sites IV to IX. Leeches were widespread in the study area. Empirical Biotic Index values that reflect impacts of organic wastes on benthic invertebrate communities were within a narrow range, 3.16 to 6.38, and indicated 'slightly enriched' to 'enriched' water. Of the total 186 benthic invertebrate taxa, 82% had quality values 0 to 5 that indicate overall 'clean water' conditions. The predominant benthic invertebrates in the Suwannee River were detritivorous and the communities reflected oligotrophic to mesotrophic waters.