Settlement and Early Post-Settlement Survival of Sessile Marine Invertebrates on Topographically Complex Surfaces: The Importance of Refuge Dimensions and Adult Morphology

We predicted that both refuge dimension and growth form would influence settlement and short-term post-settlement success (≤7 d) of sessile marine invertebrates that live attached to hard substrata in low energy environments. Individuals with unlimited attachment to the substrata should rapidly be protected by their growth form, thus decreasing their need to settle in refuges and limiting the length of time any locations on heterogeneous substrata act as refuges. Alternatively, organisms with limited attachment to the substrata should remain susceptible to the causes of mortality for a longer time, and as a result should settle in high quality refuges (sites that protect individuals from competitors, predators or physical disturbance events until either a size refuge or reproductive maturity is obtained). Results agreed with these predictions for 4 species of invertebrates examined on both the topographically complex surface of the solitary ascidian Styela plicata (hereafter Styela) and on settlement plates with uniformly spaced roughness elements that mimicked the heights of roughness elements (2.0 and 5.0 rnm) found on Styela in Beaufort, North Carollna, USA. On all surfaces, the 2 species with limited attachment to the substrata, Balanus sp. (aclonal, solitary) and Bugula neritina (clonal, arborescent), settled almost exclusively in the location that provided individuals with the best refuge: the crevices formed where the bases of roughness elements intersect with the flat surfaces. Additionally, when roughness elements of various heights were present (Styela, range: 0 6 to 8.8 mm), intermediate size roughness elements (2.0 ˂ x ≤15.0 mm) were picked over 72% of the time. Settlement locations and locations where survival were enhanced were less consistent for the 2 species with unlimited attachment to the substrata: a clonal, encrusting form (Schjzoporella errata) and a clonal stolon-mat form (Tubularia crocea). Fewer individuals of these 2 species settled on roughness elements on Styela and when they did, they were not restricted to the bases of the roughness elements. On the plate surfaces, most settlement did occur in crevices, but both species grew away from this location within days and short-term survival was not consistently greater in this location. Additional trials were run on plates with pits of the same maximum dimensions as the tested roughness elements (2.0 and 5.0 mm depth) to see if crevices and pits provide refuges of equal quality for newly settled individuals. Only survival of Balanus sp. recruits was greatest in both crevices and pits. Evidence for active choice of settlement location comes from consistent results in trials in which some larvae settled in greater numbers on specific size roughness elements on Styela and in areas of high erosion. Overall, these results show that one must be very cautious when generalizing about refuge quality on heterogeneous surfaces, and to determine if a location is a spatial refuge, it is critical to consider: (1) the dimensions of the larva, (2) the relative dimensions of the individual and potential refuge location at any point in time from the moment settlement occurred, and (3) the growth form of the individual which is related to its need for protection from biotic and abiotic sources of mortality

Quantifying Spatial Patterns of Overgrowth in Epibenthic Communities

A method is presented that allows rapid and accurate measurement of changes in the spatial pattern of space occupation in encrusting organisms. The boundaries of organisms are represented as polygons, and geometric difference calculations are used to establish the perimeters of the areas gained or vacated between sampling dates. The influence of interspecific interactions on occupation of space is also quantified: geometric intersection calculations are used to define the perimeters of the areas gained or lost in overgrowth interactions. A method is presented for estimating the sampling frequency necessary for detection of significant changes in occupation of space. The method provides a means of quantifying not only changes in percent cover and diversity but also the dynamics of colony movement and the rates and outcomes of competitive interactions

Biodiversity of sessile and motile macrofauna on intertidal oyster reefs in Mosquito Lagoon, Florida

Our research focused on determining the diversity and abundance of sessile and motile macrofauna that use intertidal reefs of the eastern oyster Crassostrea virginica for feeding, settlement space or refuge in Mosquito Lagoon, Florida. Five replicate lift nets were deployed at six sites (three impacted reefs with seaward margins of disarticulated shells, three reference reefs Without dead margins) to determine the species composition and numbers present on these reef types. All nets were deployed intertidally on backreef areas on living oyster reefs, just above mean low water. One and a half liters of live oysters and oyster shells were placed in each net (1m(2)) on deployment. Nets were surveyed for all fauna monthly for one year. Metrics used to evaluate habitat Use were species richness (total number of different species found) and density (total number of organisms per net). Comparisons were also made between community assemblages found on the two different types of reefs in the area (with and without dead margins) and for sessile species, recruitment on living oysters versus disarticulated shells. Forty sessile and 64 motile species of macroorganisins were found utilizing the oyster reefs in Mosquito Lagoon. However, recruitment on live oysters was twice that on disarticulated shells. Significant temporal variations were documented. When the two reef types were compared, however, no differences were found

Recreational boating activity and its impact on the recruitment and survival of the oyster Crassostrea virginica on intertidal reefs in Mosquito Lagoon, Florida

Along the east coast of central Florida in the Indian River Lagoon system, intense recreational boating activity occurs year-round, and intertidal reefs of the eastern oyster Crassostrea virginica (Gmelin) with dead margins (mounds of disarticulated shells) on their seaward edges are commonly found adjacent to major boating channels. These dead margins are caused, at least in part, by boat wakes and extend significantly higher above the high water line than reefs lacking dead margins (pristine reefs). To determine if these impacted oyster reefs alter recruitment and subsequent survival of C. virginica, three 8-wk field trials were run between May 2001 and April 2002 in Mosquito Lagoon. During each trial, data were also collected on total sediment loads, silt/clay fractions and relative water motion. Although recruitment did not differ between impacted and pristine reef\u27s, juvenile survival was significantly reduced on impacted reefs. Additionally, larval recruitment and subsequent mortality were greatest during our summer trial. Total sediment loads, percent silt/clay, and relative water motion were significantly higher on impacted reefs. For these three variables, the largest values were consistently found at the bases of exposed (seaward) regions of impacted reefs. By documenting a positive relationship between reduced success of C. virginica and dead margins, and knowing that boat wakes contribute to the development of dead margins. we have provided the first cause and effect mechanism between intense recreational boating activity and increased oyster morality

E-commerce and Caulerpa: unregulated dispersal of invasive species

Professional aquarists and hobbyists are thought to be the source of invasions of the aquarium strain of the green macroalga Caulerpa taxi folia in the Mediterranean, southern California, and Australia. The US Department of Agriculture, Animal and Plant Health Inspection Service (USDA-APHIS) restricted interstate commerce and importation of the Mediterranean clone of C taxi folia prior to the California invasion and is currently deciding if it should strengthen regulation of this genus as more species of Caulerpa are being described as invasive. Here we document the importance of e-commerce as a mode of dispersal for many species of Caulerpa in the United States. We purchased Caulerpa from 30 internet retailers and 60 internet auction sites representing 25 states and Great Britain. Twelve different Caulerpa species were confirmed using DNA sequencing. Only 10.6% of sellers provided the correct genus and species names with their shipments. Thirty purchases of live rock provided four species of Caulerpa, as well as 53 additional marine species. Our results confirm the extensive e-commerce availability of this invasive genus and its high dispersal potential via postal services and hobbyists. We recommend that both eBay and the USDA maximize regulation of Caulerpa

Mapping Emotional Attachment as a Measure of Sense of Place to Identify Coastal Restoration Priority Areas

Our applied case study demonstrates how knowledge from community stakeholders about emotional attachment (as a key component of sense of place) can inform and influence future coastal restoration priorities at various scales in the Indian River Lagoon, Florida (USA). We map aggregate measures of emotional attachment from community stakeholders using Geographic Information Systems. We then analyze this human systems level data with kernel density estimation measures at the broader lagoon scale and with inverse distance weighted measures at more localized scales. By connecting these mapped results back to the primary reasons that participants provided for having high or low emotional attachment in a location, we show how varying spatial patterns of emotional attachment as a primary component of sense of place within and across broader geographic regions can be represented, mapped, and visualized to enhance future restoration priorities. We demonstrate how aggregate results gained from community stakeholders can help restoration teams prioritize their science communication and education strategies to align human systems level data with natural systems level data

Life on Jackson Creek, Smith County, Texas: Archeological Investigations of a 14th Century Caddo Domicile at the Leaning Rock Site (41SM325)

The 14th century Caddo Leaning Rock site was initially discovered in the Fall of 2004. It was located during reconnaissance to search out a location for the survey portion of the Texas Archeologica! Society\u27s Academy IO I held in Tyler in February 2005. This was not a formal survey with transect lines. nor one using regularly spaced shovel tests. but was rather more of a windshield \u27 type survey, consisting of driving across pasture lands looking at gopher mounds and checking fore, evidence of archeological deposits on likely looking landforms. !n this area. landform and soil type seem to be the major determining factors in locating Caddo sites. The sandy soils in the scattered gopher mounds appeared almost white. especially in droughty conditions that prevailed at the time. causing an area with darker mounds of soil to catch my attention. Pocket gophers (G. breviceps) can play havoc with buried archeological deposits but can also be useful in bringing buried soils along with archeological materials to the surface from their underground tunnel system. While this dark area could have been the result of past historic land clearing and burning activities. a closer inspection revealed burned bone. mussel she!L and Caddo sherds mixed in the dark brown soils in the scattered gopher mounds. The next step was to record the site with the State of Texas, obtaining the trinomial 41SM325. It is common practice to also gin: sites informal names and after recording several hundred sites, selecting a name becomes a challenge. One large sandstone slab, pan of the R-horizon that is exposed around the margins of Leaning Rock. was unearthed during prior landclearing activities and pushed up against a lonely pine tree on the northern margins of the site: consequently the nom de plume Leaning Rock

Synergistic Effects of Salinity and Temperature on the Survival of Two Nonnative Bivalve Molluscs, Perna viridis

This study examined the combined salinity and temperature tolerance of two marine bivalve molluscs, Perna viridis and Mytella charruana, which have recently invaded the southeastern United States. It is essential to understand the role that these abiotic variables play in invasions and establishment of nonnative species. We simultaneously explored survival at three salinity ranges (5–9, 20–22.5, and 35–40 ppt) in both cold and warm water for juveniles and adults of both species. We determined that Perna viridis can survive at a wide range of temperatures (9–35°C) when the salinity is 35–37 ppt; however, as salinity decreased, the thermal survival range for P. viridis became narrower. With M. charruana, our data suggest that juvenile and adult individuals can survive at a wide range of salinities (5–40 ppt) at 20°C, but the salinity tolerance range narrowed as the temperature decreased or increased. Additionally, we observed that temperature rapidly impacted survival of P. viridis and M. charruana (within hours), while salinity impacts were more gradual (days to weeks). These data can be used to help predict successful introductions and future expansions of P. viridis and M. charruana in introduced habitats

Estimation of Dietary Iron Bioavailability from Food Iron Intake and Iron Status

Currently there are no satisfactory methods for estimating dietary iron absorption (bioavailability) at a population level, but this is essential for deriving dietary reference values using the factorial approach. The aim of this work was to develop a novel approach for estimating dietary iron absorption using a population sample from a sub-section of the UK National Diet and Nutrition Survey (NDNS). Data were analyzed in 873 subjects from the 2000–2001 adult cohort of the NDNS, for whom both dietary intake data and hematological measures (hemoglobin and serum ferritin (SF) concentrations) were available. There were 495 men aged 19–64 y (mean age 42.7±12.1 y) and 378 pre-menopausal women (mean age 35.7±8.2 y). Individual dietary iron requirements were estimated using the Institute of Medicine calculations. A full probability approach was then applied to estimate the prevalence of dietary intakes that were insufficient to meet the needs of the men and women separately, based on their estimated daily iron intake and a series of absorption values ranging from 1–40%. The prevalence of SF concentrations below selected cut-off values (indicating that absorption was not high enough to maintain iron stores) was derived from individual SF concentrations. An estimate of dietary iron absorption required to maintain specified SF values was then calculated by matching the observed prevalence of insufficiency with the prevalence predicted for the series of absorption estimates. Mean daily dietary iron intakes were 13.5 mg for men and 9.8 mg for women. Mean calculated dietary absorption was 8% in men (50th percentile for SF 85 µg/L) and 17% in women (50th percentile for SF 38 µg/L). At a ferritin level of 45 µg/L estimated absorption was similar in men (14%) and women (13%). This new method can be used to calculate dietary iron absorption at a population level using data describing total iron intake and SF concentration