Hydrologic analysis for coastal wetland restoration

Increasing recognition of the value of tidal wetlands has led to interest in how to restore and enhance areas that have been modified by human activity. The policy of recognizing restoration or enhancement as mitigation for destruction of other wetlands is controversial. Once policy questions are separated from technical questions, the steps in a successful project are straightforward A key element in the design of a successful project is quantitative hydraulic and hydrologic analysis of alternatives. Restoration projects at two sites in California used a combination of empirical geomorphic relationships, numerical modeling, and verification with field observations. Experience with these and other wetland restoration projects indicates the importance of longterm postproject monitoring, inspection, and maintenance     

Automated sizing,counting and identification of zooplankton by pattern recognition

A computerized system was developed to automate the analysis of zooplankton samples. Classification to major taxonomic group was based on discriminant analysis of morphological features. Images were generated either from preserved organisms or from silhouette photographs. The latter technique simplified large-scale sample storage. Accuracy of correct classification, among organisms regularly occurring in New England coastal waters, exceeded 90%. Critical problems were due to limitations inherent to the imaging of low contrast, randomly oriented objects by a vidicon camera. One solution would utilize an incoherent-to-coherent transducer in a binocular field of observation through which plankton entrained in a flowing medium passed.This work was supported in part by NOAA grant NA80AA-4 00023     

Density and extra-pair fertilizations in birds: a comparative analysis

Møller and Birkhead (1992, 1993) reported that extra-pair copulations (EPCs) occur more frequently in colonial than dispersed nesting birds. We comprehensively reviewed published data to investigate how breeding density affects extra-pair fertilizations (EPFs). Within species EPFs appeared to increase with density: two of three studies on colonial breeders and six of eight on dispersed nesters showed increases in EPFs with increasing density. However, comparisons among species (n?=?72) revealed no evidence that EPF frequencies correlated with (1) nesting dispersion, (2) local breeding density, or (3) breeding synchrony, even when each of these variables in turn was held constant and phylogenetic relationships were taken into account via contrast analyses. Methodological and biological reasons for the disparity between observational studies of EPCs and molecular genetic analyses of EPFs are discussed.     

Pelagic Sargassum community change over a 40-year period: temporal and spatial variability

Pelagic forms of the brown algae (Phaeophyceae) Sargassum spp. and their conspicuous rafts are defining characteristics of the Sargasso Sea in the western North Atlantic. Given rising temperatures and acidity in the surface ocean, we hypothesized that macrofauna associated with Sargassum in the Sargasso Sea have changed with respect to species composition, diversity, evenness, and sessile epibiota coverage since studies were conducted 40 years ago. Sargassum communities were sampled along a transect through the Sargasso Sea in 2011 and 2012 and compared to samples collected in the Sargasso Sea, Gulf Stream, and south of the subtropical convergence zone from 1966 to 1975. Mobile macrofauna communities exhibited changes in community structure and declines in diversity and evenness within a 6-month time period (August 2011–February 2012). Equivalent declines in diversity and evenness were recorded in the same region (Sargasso Sea, 25°–29°N) in 1972–1973. Recent community structures were unlike any documented historically, whether compared to sites of the same latitude range within the Sargasso Sea, or the broader historical dataset of sites ranging across the Sargasso Sea, Gulf Stream, and south of the subtropical convergence zone. Recent samples also recorded low coverage by sessile epibionts, both calcifying forms and hydroids. The diversity and species composition of macrofauna communities associated with Sargassum might be inherently unstable. While several biological and oceanographic factors might have contributed to these observations, including a decline in pH, increase in summer temperatures, and changes in the abundance and distribution of Sargassum seaweed in the area, it is not currently possible to attribute direct causal links.     

Within-population variation in ejaculate characteristics in a prolonged breeder,Peron’s tree frog, <Emphasis Type="Italic">Litoria peronii</Emphasis>

Sperm number is often a good predictor of success in sperm competition; however, it has become increasingly clear that, for some species, variation in probability of paternity cannot be explained by sperm number alone. Intraspecific variation in ejaculate characteristics, such as the number of viable sperm and sperm longevity, may play an equally important role in determining fertilization success. Here, we assess variation among ejaculates in three factors that may contribute to fertilization success (number of sperm per ejaculate, viability, and longevity), in a population of Peron’s tree frog (Litoria peronii). We detected large variation among males in the number of sperm per ejaculate and the proportion of viable sperm within ejaculates, which could not be explained by variation in either male size or body condition. However, the proportion of viable sperm released by males increased over the season. Finally, we assessed sperm longevity (proportion viable sperm determined using a dual-fluorochrome vital dye) at two different temperatures. At 23°C, on average, 75% of sperm remained viable after 2 h, but there were significant differences amongst males with the percentage of viable sperm ranging from 43% to 95%. For sperm incubated at 4°C, ejaculates varied fivefold in sperm longevity with some males having 50% viable sperm after 5 days. Our data suggest that ejaculate characteristics (sperm number, viability, and longevity) vary widely in Peron’s tree frog and may therefore play an important role in determining siring success both in the presence and absence of sperm competition. We discuss the results in relation to selection on ejaculate traits via natural and sexual selection in this and other amphibians.     

Database-driven models of the world's Large Marine Ecosystems

We present a new methodology for database-driven ecosystem model generation and apply the methodology to the world's 66 currently defined Large Marine Ecosystems. The method relies on a large number of spatial and temporal databases, including FishBase, SeaLifeBase, as well as several other databases developed notably as part of the Sea Around Us project. The models are formulated using the freely available Ecopath with Ecosim (EwE) modeling approach and software. We tune the models by fitting to available time series data, but recognize that the models represent only a first-generation of database-driven ecosystem models. We use the models to obtain a first estimate of fish biomass in the world's LMEs. The biggest hurdles at present to further model development and validation are insufficient time series trend information, and data on spatial fishing effort.     

Sulfur isotopes link overwinter habitat use and breeding condition in Double-crested Cormorants.

North American Double-crested Cormorant (Phalacrocorax auritus) populations have increased greatly. Both breeding and overwintering ground factors have likely contributed to these increases. However, demonstrating how overwintering conditions may affect breeding birds has not been possible because of the difficulty in linking breeding birds to their wintering grounds. Here, we demonstrate the utility of stable sulfur isotopes to elucidate overwintering habitat use by cormorants breeding on Lake Erie. Sulfur isotopes in feathers grown on overwintering grounds provided insights into the degree to which birds used freshwater vs. marine environments. The proportion of birds utilizing freshwater habitats increased through time. This change may have reflected increases in freshwater aquaculture (i.e., catfish) in the U.S. south. Examination of body condition in birds returning to breed on Lake Erie indicated that those individuals that solely used marine habitats for at least a portion of the overwintering period were in poorer condition than birds using freshwater. Enhanced foraging opportunities at aquaculture facilities may improve the fitness of individuals that have returned to breed after overwintering at such locations. This study is the first to demonstrate a linkage between overwinter habitat use and breeding ground parameters in Double-crested Cormorants. These results underscore that factors throughout the Mississippi flyway are likely acting together to regulate cormorant populations.