Invasion Ecology: Effects of Habitat Alteration on the Survival of an Exotic Species

Metadata:

Identification_Information:
Citation:
Citation_Information:
Originator:
Dauphin Island Sea Lab's (DISL) Valentine Lab
Publication_Date:
Unknown
Title:
Invasion Ecology: Effects of Habitat Alteration on the Survival of an Exotic Species
Description:
Abstract:
The Dr. John Valentine Lab at the Dauphin Island Sea Lab reports the findings of a three year study conducted in the upper reaches of the Mobile Bay Estuary and the lower Mobile Tensaw Delta (MTD). This study evaluates, to the extent possible, that variability in disturbance intensity arising from hydrological modification of estuarine hydrology determines the abundance and distribution of one of the most common exotic submerged aquatic vegetation (SAV) species found in the area, Eurasian milfoil (Myriophyllum spicatum). Prior to this study, no one has experimentally evaluated the impacts of habitat forming exotic SAV species on native SAV species in the Northern Gulf of Mexico. Furthermore, none have evaluated the extent to which natural disturbances or variations in local hydrography control the spread of these exotics in estuarine waters.
Purpose:
The purpose of this study is to evaluate how disturbance intensity of the estaurine hydrology in Mobile Bay affects the abundance and distribution of the SAV Eurasian milfoil (Myriophyllum spicatum), and how Eurasian milfoil affects the native SAVs in Mobile Bay.
Time_Period_of_Content:
Time_Period_Information:
Range_of_Dates/Times:
Beginning_Date:
20051101
Ending_Date:
20071031
Currentness_Reference:
ground condition
Status:
Progress:
Complete
Maintenance_and_Update_Frequency:
Unknown
Spatial_Domain:
Bounding_Coordinates:
West_Bounding_Coordinate:
-88.0096
East_Bounding_Coordinate:
-87.9365
North_Bounding_Coordinate:
30.7271
South_Bounding_Coordinate:
30.6671
Keywords:
Theme:
Theme_Keyword_Thesaurus:
None
Theme_Keyword:
invasive species
Theme_Keyword:
exotic species
Theme_Keyword:
Eurasian milfoil
Theme_Keyword:
Myriophyllum spicatum
Theme_Keyword:
habitat
Theme_Keyword:
estuary
Theme_Keyword:
ecosystem
Theme_Keyword:
submerged aquatic vegetation
Theme_Keyword:
disturbance
Theme_Keyword:
hydrological modification
Theme_Keyword:
species abundance
Theme_Keyword:
species distribution
Theme:
Theme_Keyword_Thesaurus:
ISO Topic
Theme_Keyword:
biota
Theme_Keyword:
002
Theme_Keyword:
environment
Theme_Keyword:
007
Theme_Keyword:
oceans
Theme_Keyword:
014
Theme_Keyword:
inlandWaters
Theme_Keyword:
012
Place:
Place_Keyword_Thesaurus:
None
Place_Keyword:
Mobile
Place_Keyword:
Alabama
Place_Keyword:
Mobile Bay Estuary
Place_Keyword:
Northern Gulf of Mexico (NGOM)
Place_Keyword:
Mobile Tensaw Delta (MTD)
Place_Keyword:
Polecat Bay
Place_Keyword:
Delvan Bay
Place_Keyword:
Chocolotta Bay
Place_Keyword:
Justin's Bay
Place_Keyword:
Grand Bay
Place_Keyword:
Chuckfee Bay
Place_Keyword:
Chacallochee Bay
Place_Keyword:
Big Bateau
Place_Keyword:
Little Bateau
Place_Keyword:
Bay Minette Basin
Place_Keyword:
Blakely River
Place_Keyword:
Tensaw River
Place_Keyword:
Appalachee River
Place_Keyword:
Mobile River
Place_Keyword:
Mobile Bay Causeway
Access_Constraints:
Please contact Dr. John Valentine for information on accessing these data.
Use_Constraints:
Acknowledgment of DISL: Valentine Lab and the Alabama Center for Estuarine Studies (ACES) would be appreciated in products developed from these data, and such acknowledgment as is standard for citation and legal practices for data source is expected by users of these data. Users should be aware that comparison with other data sets for the same area from other time periods may be inaccurate due to inconsistencies resulting from changes in mapping conventions, data collection, and computer processes over time. The distributor shall not be liable for improper or incorrect use of these data, based on the description of appropriate/inappropriate uses described in the metadata document. These data are not legal documents and are not to be used as such.
Point_of_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person:
Dr. John Valentine
Contact_Organization:
DISL: Valentine Lab
Contact_Position:
Principal Investigator
Contact_Address:
Address_Type:
mailing and physical
Address:
101 Bienville Blvd.
City:
Dauphin Island
State_or_Province:
Al
Postal_Code:
36528
Country:
USA
Contact_Voice_Telephone:
251-861-2141 ext. 2261 or 2294
Contact_Electronic_Mail_Address:
jvalentine@disl.org
Hours_of_Service:
8-5:00 CST
Contact_Instructions:
Please email Dr. John Valentine for further information.
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Data_Quality_Information:
Attribute_Accuracy:
Attribute_Accuracy_Report:
Quality control was achieved through a variety of practices. Multiple technicians working on the SAV survey routinely double-checked randomly selected dry weight measurements of SAV samples to ensure biomass estimation was accurate. In measuring hydrodynamic variables, post calibration procedures were performed to make certain the data was valid and any questionable values were investigated by either inspecting the data to see if there could be an explanation for the uncertain reading (for example, by tides, time or wind forcing) or checking the Meaher Park continuous monitoring buoy (in the case of wind speeds and turbidity). Duplicate water samples were used in both the collection and analysis of nutrient variability to ensure accurate assessment of nutrient concentrations during each sampling event. In all comparisons, transformations of data were performed when either of the assumptions of ANOVA (normality or homogeneity of variance) was violated and treatments were considered to be significantly different from one another when p< 0.05. Comparisons of plant community composition in the field survey were made using the non-parametric multivariate Analysis of Similarity (ANOSIM; square root transformed, Bray-Curtis similarity) technique (Warwick & Clarke 1991). Similarity percentages (SIMPER) were used to further explore the data when differences were detected. Both ANOSIM and SIMPER comparisons were made using the multivariate nonparametric software package Primer-E. One-way Analysis of Variance (ANOVA) and t-tests were used to analyze the data found in Vittor (2003), and to compare the distributional patterns of milfoil and native species. Two-way ANOVAs were used to determine if water column nutrient concentrations varied among sites and months. T-tests compared the ratios of carbon to nitrogen in plants collected north and south of the causeway. In the lab experiment, the response of milfoil to salinity stress and sediment type was compared using a 2-way ANOVA. For interspecific competition experiments, a 2-way ANOVA was used to test for effects of treatment (salinity and presence/absence of milfoil) on growth of wild celery (as determined by plant weight).
Logical_Consistency_Report:
not applicable
Completeness_Report:
Data was gathered and processed in the lab from 20051101-20071031 with no major lapses in collection.
Lineage:
Process_Step:
Process_Description:
Analysis of the Vittor (2003) data set: The distributional patterns of submerged aquatic vegetation in Mobile Bay was mapped in 2002 by Barry A. Vittor and Associates using GIS (accessible at Mobile Bay NEP’s website: http://www.mobilebaynep.com/site/news_pubs/Publications/MBNEP_SAVrpt.pdf). We utilized these data (Figure 3) to observe the spatial distributional patterns of milfoil in our study area. In general, the northernmost waters in the MTD (those closest to the freshwater discharge of the watershed) have lower salinities than do waters closer to Mobile Bay (Berrell 2002). If salinity does control the distribution of milfoil, then the aerial coverage of SAV should be greater in areas with lower salinities (northernmost sites) than in areas where higher salinities are observed. SAV Survey To determine if differences in the relative abundances of native and invasive species existed among sites at a much smaller scale than those detected in the Vittor study which very qualitative in nature, we conducted replicated sampling in specific grass beds throughout an entire growing season (May to September). Samples were taken every two months at 40 preselected grass bed sites (20 sites located north and the remaining sites south of the causeway. Replicate 10 cm diameter cores were taken at 5 locations within each grass bed. Cores were placed into individual Ziploc bags which were then placed on ice, and returned to DISL for processing. Upon return, SAV samples were sorted by species, lengths of milfoil and wild celery, the dominant native species, were measured (+ 1mm) with a ruler. All of the SAV species were individually dried to a constant weight at 60oC in a drying oven. Sample weight was then recorded for each species (+ 0.001mg). Hydrographic Conditions: To determine the extent to which hydrographic conditions vary on each side of the causeway (and to determine if these differences could influence the composition of SAV communities in the lower MTD), measurements were taken throughout the growing season (May – December) at a representative location selected on each side of the causeway. A YSI 6600 was deployed in Chocolatta Bay, north of the causeway and at the USS Alabama pier at Battleship Park to south of the causeway. The instruments were mounted horizontally on a PVC frame which was lowered onto the sediment-water interface. Deployed instruments, replaced at two to three week intervals, were programmed to measure water temperature (oC), specific conductance, and turbidity (NTU) at 15 minute intervals. Salinity was calculated from the recorded specific conductance and temperature using an algorithm. Water Column: Nutrient variability among areas sampled north of the causeway (Polecat Bay, Delvan Bay, Tensaw River, Chocolatta Bay, Apalachee River, Justin’s Bay, Blakely River) and directly to the south (multiple sites across the bay from USS Alabama to D’Olive Bay) was documented by taking collections from directly below the water surface in triple-rinsed bottles. The bottles were immediately placed on ice (at approximately 2oC) and returned to the lab for analysis using methods published in Pennock and Cowan (1998). C:N ratio of SAV: In general, plants found in eutrophic areas contain more nitrogen in their tissues than do plants living in more oligotrophic environments (Goecker et al 2005). To determine if either the carbon content or nitrogen content in the tissues of the two dominant species in the area (milfoil or wild celery) differed on each side of the causeway and to determine if nutrient availabilities were positively correlated with areas of milfoil infestation, the ratio of these elements in leaf tissues of each plant were compared with causeway location. These tissues were extracted from plants collected in cores taken during months of May and July during the small scale SAV survey. In the laboratory, these tissues were dried to a constant weight at 60oC, ground into a fine powder with a grinder, and the relative concentrations of carbon and nitrogen in their tissues were analyzed using a Costech CNS analyzer. LABORATORY METHODS Salinity as a Barrier for Milfoil: While milfoil has been successful in colonizing some rivers and bays feeding into Mobile Bay, it’s not well established in others (Vittor 2003, personal observation). Among the potential factors that could inhibit the spread of Eurasian milfoil within the lower MTD is causeway-induced variation in salinity. Salinity peaks in the MTD during fall when the salt wedge encroaches northward to its furthest point (Berrell 2002). There is evidence that the presence of the causeway reduces tidal intrusion during these months resulting in large differences in water column salt content spatially (Figure 4). Previous studies have indicated that Eurasian milfoil biomass is negatively correlated with salinity (Haller et al 1974, Frazer et al 2006) suggesting that alteration of hydrology could be a key determinant of the milfoil distributional pattern in the MTD. Further evidence comes from the observation that, after Hurricane Katrina pushed saline waters into the MTD in September 2005, a noticeable decline in Eurasian milfoil coverage was observed (J. Valentine, personal communication). To date, however, there have been no experimental evaluations of the impacts of increasing salinity on the growth of milfoil within the MTD. Here, we link observational data collected in areas with high and low salinity to manipulative experimentation conducted in the wet lab at DISL to determine the extent to which the observed variation in salinity may explain variation in milfoil coverage. This ANOVA-designed laboratory experiment consisted of 3 salinity treatments (0, 5, and 15psu) that bracketed the range of values observed over the growing season in the MTD. Each treatment was replicated in six randomly selected 98L tanks. Ten plants were stocked in each tank. The plants were collected from the field, placed in a cooler with ambient water and an airstone, and returned to DISL. Epiphytes, algae, dead tissue, and herbivores were removed by hand, and then the plants were placed in a salad spinner, which was turned for approximately 1 minute, to remove excess water before weighting placement in the experimental tanks. Salinity in each tank was increased at a rate of 1psu per day in each tank until the desired treatment salinity was reached. Lighting (held constant between 150-250 lumens during daylight hours) was on a cycle of 12 hours (12 hours of light and 12 hours dark in a 24 hour period) to mimic natural lighting conditions during the summer months. All tanks were maintained such that their predetermined salinities did not change throughout the experiment and relevant measures such as pH and temperature were monitored weekly during the experiment. Algae was scrubbed off the tank walls as needed. At the end of the experiment, plants were removed from the tanks and returned to the salad spinner to remove excess water. Final wet weights (+ 0.01g) were used to compare treatment impacts on milfoil growth. We further hypothesized that differences in sediment composition observed on each side of the causeway could influence the growth of milfoil. Supporting evidence for variability in sediment type with causeway location comes from data collected in 2001 (Valentine and Sklenar 2005) (Figure 5). The results indicate that areas north of the causeway contain less sand (hereafter referred to as “mud”) than do areas to the south. As such, a second factor (sediment type) was added to the experimental design. This factor consisted of two treatments (mud from north of the causeway and sand from south). Each treatment was replicated three times and each set of replicates was randomly assigned to each salinity. To determine if Eurasian milfoil became the abundant of the SAVs found in the MTD by competitively displacing native SAV, as current invasion theory suggests, we also performed a manipulative laboratory interspecific competition experiment using the exotic milfoil and the dominant native grass in the MTD, Vallisneria americana (wild celery). This experiment again took place in Dauphin Island Sea Lab’s recirculating wet lab facility, and results were used to evaluate the impacts of milfoil on the growth of wild celery. Because salinity can vary greatly among locations within the MTD, we also sought to determine if the intensity of this potentially negative interaction might vary across a range of ecologically relevant salinities. Two main effects (presence of milfoil and variation in salinity) on wild celery growth were tested in this factorial design. Each treatment consisted of 3 replicates which were randomly assigned to a series of experimental tanks. Three salinities (again 0, 5, and 15 psu) were used with replicates of wild celery grown in monoculture and wild celery grown with milfoil at each salinity. In each tank containing wild celery only, 10 plants were harvested from the field, placed in a cooler with water and an airstone, and replanted in a 98L tank at DISL. For each tank containing wild celery and milfoil, 5 milfoil plants and 5 wild celery plants were randomly planted in tanks using methods previously mentioned for the salinity tolerance experiment. Procedures for herbivore and epiphyte/algae removal, lighting, light/dark cycle, sediment type (mud from Chocolatta Bay), and maintenance of tanks were identical to that mentioned above for salinity experiments.
Process_Date:
20071031
Process_Contact:
Contact_Information:
Contact_Person_Primary:
Contact_Person:
Dr. John Valentine
Contact_Organization:
DISL: Valentine Lab
Contact_Position:
Principal Investigator
Contact_Address:
Address_Type:
mailing and physical
Address:
101 Bienville Blvd.
City:
Dauphin Island
State_or_Province:
Al
Postal_Code:
36528
Country:
USA
Contact_Voice_Telephone:
251-861-2141 ext. 2261 or 2294
Contact_Electronic_Mail_Address:
jvalentine@disl.org
Hours_of_Service:
8-5:00 CST
Contact_Instructions:
Please email Dr. John Valentine for further information.
Back To Index
Entity_and_Attribute_Information:
Overview_Description:
Entity_and_Attribute_Overview:
Excel tables cataloging data concerning submerged aquatic vegetation in the following categories: Carbon to Nitrogen ratios; vegetation fragment experiments including tensile strength, rooting and tethering; hydrographic conditions; salinity effects; GIS mapping of Mobile Tensaw Delta from 2003 (Vittor); interspecific competition; and biomass surveys.
Entity_and_Attribute_Detail_Citation:
The Carbon: Nitrogen data contains the following attributes: weight (mg), %N, %C, N(mg), C(mg), C(mmol), N(mmol), water C:N ratio, Vallisneria americana C:N ratio, and Eurasian milfoil C:N ratio.
Entity_and_Attribute_Detail_Citation:
Vegetation fragmentation experiments include: fragment density, distance from bed (m), volume (m3), # fragments in tow, and fragments/m3.
Entity_and_Attribute_Detail_Citation:
Rooting with salinity experiments include: salinity, date, time, time from start, hours total, and length.
Entity_and_Attribute_Detail_Citation:
Tensile strength tests (pull tests) with salinity (0, 5, 15 PSU respectively) include: PSU, length, forge (kg).
Entity_and_Attribute_Detail_Citation:
Tethering experiments measuring survivorship includes % survivorship under varying ratios of Vallisneria americana to Eurasian milfoil.
Entity_and_Attribute_Detail_Citation:
Hydrographic conditions (wave action/velocity) were measured using gypsum. A pre-weight, final weight, difference in weight, and %loss was documented.
Entity_and_Attribute_Detail_Citation:
YSI data includes: date, time, temperature (C), pressure (psia), depth (m), hourly mean, and distance from hourly mean.
Entity_and_Attribute_Detail_Citation:
Salinity effects were tested for both Vallisneria americana and Eurasian milfoil. The data includes: start date, end date, days total, salinity (o,5,15 PSU), tank, plant, sediment (mud or sand), initial wet weight (WW) (g), final WW (g), final WW (no dead), WW difference "dead" (g), %dead/plant, # new shoots, pieces WW (g), pieces WW no dead (g), pieces WW difference, dead WW (tank), total dead WW (tank+plants), total all with dead WW, new growth with dead (g), new growth with dead (g/day), % new growth, total all, no dead WW, new growth no dead (g), new growth no dead (g/day), %, filter number, filter + algae WW, algae WW, filter dry weight (DW) (g), filter + algae DW, algae DW, # pieces total, new shoots, STD new shoots, total flowers, short bud tips, short stalks, medium stalks, short stalks with flowers, medium stalks with flowers, spent, total flowers, stalks with flowers, stalks without flowers.
Entity_and_Attribute_Detail_Citation:
GIS mapping of Mobile Tensaw Delta conducted by Vittor in 2003 was analyzed. This data includes: water area (m2), E. milfoil(m2), V. americana (m2), E. milfoil/area, V. americana/area, E. milfoil: V.americana. Survey information North and South of causeway contains the following data: SAV (E.milfoil or V. americana), area (acres), area (m2), area of water (sq. ft.), area of water (m2), SAV area/area of water.
Entity_and_Attribute_Detail_Citation:
Interspecific competition data includes: plant#, # V. americana blades, # E. milfoil branches, intitial lengths, final lengths, # V.americana flowers, treatment, chlorophyll a, chlorophyll b, chlor a : chlor b.
Entity_and_Attribute_Detail_Citation:
SAV survey biomass data includes: raw and primer dry weights for V. americana, M. spicatum, H. dubia, Z. palustris, C. vulgaris, N. guadalupensis, R. maritima, C. demersum, and unknown grasses.
Entity_and_Attribute_Detail_Citation:
Data for sigmaplot pies includes total biomass, % total, and SAV vs. time.
Entity_and_Attribute_Detail_Citation:
Other analyses include dry weight, total SAV biomass, SAV aerial coverage %, total SAV biomass/m2.
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Distribution_Information:
Distributor:
Contact_Information:
Contact_Person_Primary:
Contact_Person:
Dr. John Valentine
Contact_Organization:
DISL: Valentine Lab
Contact_Position:
Principal Investigator
Contact_Address:
Address_Type:
mailing and physical
Address:
101 Bienville Blvd.
City:
Dauphin Island
State_or_Province:
Al
Postal_Code:
36528
Country:
USA
Contact_Voice_Telephone:
251-861-2141 ext. 2261 or 2294
Contact_Electronic_Mail_Address:
jvalentine@disl.org
Hours_of_Service:
8-5:00 CST
Contact_Instructions:
Please email Dr. John Valentine for further information.
Resource_Description:
ACES invasive SAV study
Distribution_Liability:
The Dauphin Island Sea Lab's Valentine Lab makes no warranty regarding these data, expressed or implied, nor does the fact of distribution constitute such a warranty. The Valentine Lab cannot assume liability for any damages caused by any errors or omissions in these data, nor as a result of the failure of these data to function on a particular system.
Technical_Prerequisites:
Users must have a program capable of opening Microsoft Excel spreadsheets.
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Metadata_Reference_Information:
Metadata_Date:
20100203
Metadata_Contact:
Contact_Information:
Contact_Organization_Primary:
Contact_Organization:
Dauphin Island Sea Lab
Contact_Person:
Data Management Specialist
Contact_Position:
Data Management Specialist
Contact_Address:
Address_Type:
mailing and physical
Address:
101 Bienville Blvd.
City:
Dauphin Island
State_or_Province:
Al
Postal_Code:
36528
Country:
USA
Contact_Voice_Telephone:
251-861-2141
Contact_Electronic_Mail_Address:
metadata@disl.org
Hours_of_Service:
8-5:00 CST
Contact_Instructions:
Please email the metadata specialist for further information.
Metadata_Standard_Name:
FGDC Content Standard for Digital Geospatial Metadata
Metadata_Standard_Version:
FGDC-STD-001-1998
Metadata_Access_Constraints:
none
Metadata_Use_Constraints:
none
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