Environmental and Endogenous Factors Influencing Emigration in Juvenile Anadromous Alewives

We analyzed juvenile anadromous alewife migration at Bride Lake, a coastal lake in Connecticut, during summer 2006 and found that migration on 24-hour and seasonal timescales was influenced by conditions of the environment and characteristics of the individual. To identify environmental cues of juvenile migration, we continuously video recorded fish at the lake outflow and employed information-theoretic model selection to identify the best predictors of daily migration rate. More than 80% of the approximately 320,000 juveniles that migrated from mid-June to mid-August departed in three pulses lasting one or two days. Pulses of migration were associated with precipitation events, transient decreases in water temperature and transient increases in stream discharge. Diel timing of migration shifted over the summer. Early in the season most migration occurred around dawn; late in the season migration occurred at night. To identify individual characteristics associated with migratory behavior, we compared migrating juveniles that we collected as they were exiting Bride Lake to non-migrating juveniles that we collected from the center of the lake. Migrants were a non-random subset of the population; they were on average 1 – 12 mm larger, 2 – 14 d older, had grown more rapidly (11% greater length-at-age), and were in better condition (14% greater mass-at-length) than non-migrant fish. We infer that the amount of accumulated energy has a positive effect on the net benefit of migration at any time in the migratory season.

A sex difference in seasonal timing of birth in a livebearing fish

Sex differences in seasonal timing include differences in hatch- or birth-date distribution and differences in the timing of migration or maturation such as protandrous arrival timing (PAT), which is early male arrival at breeding sites. I describe a novel form of protandrous arrival timing, as a sex difference in birth-date distribution in a live-bearing fish (Dwarf Perch, Micrometrus minimus). In this species, birth coincides with arrival at breeding sites because newborn males are sexually active. A series of samples of pregnant females and young of year was collected in Tomales Bay, CA. I analyzed the daily age record in otoliths to estimate the conception date of broods and the age that young-of-year individuals were born. Males were born at a younger age than females, as indicated by the daily age record and also by the predominance of females in broods from which some young had already been born, which was a common occurrence in pregnant females with older embryos. Sex ratio of broods varied with conception date such that early-season broods were predominantly male, possibly as a result of temperature-dependent sex determination. The combined effects of the sex difference in age at birth and seasonal shift in sex ratio were to shift the mean birth date of males relative to females by five days. The most likely ultimate explanation for PAT in the Dwarf Perch is that it arises from exploitation (scramble) competition for mating opportunities among recently-born young-of-year males.

Anadromous Rainbow Smelt and Tomcod in Connecticut: Assessment of populations, conservation status, and need for restoration plan

(beginning of rainbow smelt executive summary) Evidence indicates that anadromous rainbow smelt (Osmerus mordax) populations in Connecticut and elsewhere in the northeast United States have severely declined. Several sampling programs have documented declines in Connecticut’s smelt populations over the last three decades (Marcy 1976a, Marcy 1976b, Millstone Environmental Laboratory 2005). Similar declines have also been documented in the Hudson River (ASA Analysis & Communication 2005) and in Massachusetts (personal communication, Brad Chase, MA Division of Marine Fisheries 2004). Recreational and commercial fisheries in the region for this species have virtually ceased (Blake and Smith 1984). The Connecticut Fish Advisory Committee of the Endangered Species Program has recommended that rainbow smelt be listed as threatened in Connecticut, and the National Marine Fisheries Service (2004) has recently listed rainbow smelt as a Federal Species of Concern. The purpose of this project is to develop an environmental history of rainbow smelt in Connecticut and surrounding regions, and document the current status of populations in Connecticut waters. An environmental history that assesses trends in abundance, environmental threats and historical efforts to ameliorate the threats will contribute to regional efforts to conserve these fish. Comprehensive review of the regional literature and trends associated with rainbow smelt has not been undertaken since Kendall (1926). Assessment of current abundance, distribution, areas of critical habitat, and whether the species is presently reproducing in state waters is critical for clarifying conservation status, designing a monitoring program and developing a recovery or enhancement plan, if this appears to be necessary. (beginning of tomcod executive summary) Atlantic tomcod (Microgadus tomcod) are believed to have declined significantly in Connecticut and other estuaries of the Northeast and Middle Atlantic states. Several monitoring programs indicate that the species is scarce and/or declining in the region’s estuaries (Gottschall and Pacileo 2004, Molnar 2004, Millstone Environmental Laboratory 2005, ASA Analysis and Communication 2005). Once-active recreational (NMFS MRFSS 2005, http://www.st.nmfs.gov) and commercial fisheries for this species in Connecticut are now dormant. For the past 10 years, the Connecticut Fish Advisory Committee of the Endangered Species Program has recommended that studies be undertaken to quantify the status of tomcod populations and to determine if conservation actions should be initiated. The purpose of this project is to develop an environmental history of Atlantic tomcod in Connecticut and surrounding regions, and document the current status of populations in Connecticut waters. An environmental history that assesses trends in abundance, environmental threats and historical efforts to ameliorate the threats will contribute to regional efforts to conserve these fish. Assessment of current abundance, distribution, areas of critical habitat, and whether the species is presently reproducing in state waters is critical for determining conservation status, designing a monitoring program and developing a recovery or enhancement plan, if this appears to be necessary.

Ecological approaches and the development of “truly integrated” pest management

Recent predictions of growth in human populations and food supply suggest that there will be a need to substantially increase food production in the near future. One possible approach to meeting this demand, at least in part, is the control of pests and diseases, which currently cause a 30–40% loss in available crop production. In recent years, strategies for controlling pests and diseases have tended to focus on short-term, single-technology interventions, particularly chemical pesticides. This model frequently applies even where so-called integrated pest management strategies are used because in reality, these often are dominated by single technologies (e.g., biocontrol, host plant resistance, or biopesticides) that are used as replacements for chemicals. Very little attention is given to the interaction or compatibility of the different technologies used. Unfortunately, evidence suggests that such approaches rarely yield satisfactory results and are unlikely to provide sustainable pest control solutions for the future. Drawing on two case histories, this paper demonstrates that by increasing our basic understanding of how individual pest control technologies act and interact, new opportunities for improving pest control can be revealed. This approach stresses the need to break away from the existing single-technology, pesticide-dominated paradigm and to adopt a more ecological approach built around a fundamental understanding of population biology at the local farm level and the true integration of renewable technologies such as host plant resistance and natural biological control, which are available to even the most resource-poor farmers.

Epidemiology of Opisthorchis viverrini

Opisthorchis viverrini is a food home trematode, important because of the sheer numbers of people infected and its serious morbidities such as hepatobiliary diseases and cholangiocarcinoma (CHCA). Although infections are identified throughout Southeast Asia, the epi-center is northeast Thailand, where high prevalence coexists with a high incidence of CHCA. In this review, we present the basic population features and the factors influencing transmission between the different hosts. (C) 2003 Elsevier B.V. All rights reserved.

The competitive Darwin

Although Darwin was not the first to conceive directional selection as a mechanism of phenotypic change, it is his ideas that were received, and that have shaped population biology to this day. A significant change in his theoretical orientation occurred in the mid-1850s. About then he abandoned environmental selection in favor of competitive selection, and adopted relative adaptation with all its consequences as an alternative. These ideas changed his thinking fundamentally and shaped his argument throughout the writing of his great book. It is still these ideas that predominate today. Here I examine Darwin ' s ideas in relation to his principle of divergence, sexual selection, and the nature and origin of species. Finally I suggest that had he not misunderstood the function of sexual communication he might well have understood the nature of species and provided a more penetrating resolution to Herschell ' s mystery of mysteries, with which he opened his book.

The dynamics of a genetic algorithm under stabilizing selection

A formalism recently introduced by Prugel-Bennett and Shapiro uses the methods of statistical mechanics to model the dynamics of genetic algorithms. To be of more general interest than the test cases they consider. In this paper, the technique is applied to the subset sum problem, which is a combinatorial optimization problem with a strongly non-linear energy (fitness) function and many local minima under single spin flip dynamics. It is a problem which exhibits an interesting dynamics, reminiscent of stabilizing selection in population biology. The dynamics are solved under certain simplifying assumptions and are reduced to a set of difference equations for a small number of relevant quantities. The quantities used are the population's cumulants, which describe its shape, and the mean correlation within the population, which measures the microscopic similarity of population members. Including the mean correlation allows a better description of the population than the cumulants alone would provide and represents a new and important extension of the technique. The formalism includes finite population effects and describes problems of realistic size. The theory is shown to agree closely to simulations of a real genetic algorithm and the mean best energy is accurately predicted.

Pollination, Herbivory, and Habitat Fragmentation: Their Effects on the Reproductive Fitness of Angadenia berteroi, a Native Perennial Plant of the South Florida Pine Rocklands

Angadenia berteroi is a tropical perennial subshrub of the pine rocklands with large yellow flowers that set very few fruits. My dissertation seeks to elucidate the factors that affect the reproductive fitness of Angadenia berteroi a native species of the south Florida pine rocklands. I provide novel information on the pollination biology of this native species. I also assess the effects of herbivory on growth and the reproductive success of A. berteroi. Finally, I elucidate how habitat fragmentation and quality are correlated with reproductive fitness of this native perennial plant. Using a novel experimental approach, I determined the most effective pollinator group. I used nylon fishing line of widths corresponding to proboscis diameter of the major groups of visitors to examine pollen removal and deposition. In the field, I estimated visitation frequency and efficacy of each pollinator type. Using potted plants, I exposed flowers to single visit from different types of pollinators to measure fruit set. I performed artificial defoliation with scissors on plants growing in the greenhouse to assess the effects of defoliation before flowering as well as during flowering. Additionally, I used structural equation modelling (SEM) to elucidate how A. berteroi reproductive fitness was affected by habitat fragmentation and quality. My experiments provide evidence that Angadenia berteroi is specialized for bee pollination; though butterflies, skippers and others also visit its flowers, A. berteroi is exclusively pollinated by two native bees of the South Florida pine rocklands . This research also demonstrated that herbivory by the oleander moth may have direct and indirect effects on Angadenia berteroi growth and reproductive success. The SEM results suggested that habitat quality (litter depth and subcanopy cover) may favor reproduction in native species of the South Florida pine rocklands that are properly maintained by periodic fires and exotic control. Insights from this threatened and charismatic species may provide impetus to properly manage remaining pine rocklands in South Florida for this and other endemic understory species.

Behavioral Ecology of the Western Atlantic Short-finned Pilot Whale (Globicephala macrorhynchus)

Social structure is a key determinant of population biology and is central to the way animals exploit their environment. The risk of predation is often invoked as an important factor influencing the evolution of social structure in cetaceans and other mammals, but little direct information is available about how cetaceans actually respond to predators or other perceived threats. The playback of sounds to an animal is a powerful tool for assessing behavioral responses to predators, but quantifying behavioral responses to playback experiments requires baseline knowledge of normal behavioral patterns and variation. The central goal of my dissertation is to describe baseline foraging behavior for the western Atlantic short-finnned pilot whales (Globicephala macrohynchus) and examine the role of social organization in their response to predators. To accomplish this I used multi-sensor digital acoustic tags (DTAGs), satellite-linked time-depth recorders (SLTDR), and playback experiments to study foraging behavior and behavioral response to predators in pilot whales. Fine scale foraging strategies and population level patterns were identified by estimating the body size and examining the location and movement around feeding events using data collected with DTAGs deployed on 40 pilot whales in summers of 2008-2014 off the coast of Cape Hatteras, North Carolina. Pilot whales were found to forage throughout the water column and performed feeding buzzes at depths ranging from 29-1176 meters. The results indicated potential habitat segregation in foraging depth in short-finned pilot whales with larger individuals foraging on average at deeper depths. Calculated aerobic dive limit for large adult males was approximately 6 minutes longer than that of females and likely facilitated the difference in foraging depth. Furthermore, the buzz frequency and speed around feeding attempts indicate this population pilot whales are likely targeting multiple small prey items. Using these results, I built decision trees to inform foraging dive classification in coarse, long-term dive data collected with SLTDRs deployed on 6 pilot whales in the summers of 2014 and 2015 in the same area off the coast of North Carolina. I used these long term foraging records to compare diurnal foraging rates and depths, as well as classify bouts with a maximum likelihood method, and evaluate behavioral aerobic dive limits (ADLB) through examination of dive durations and inter-dive intervals. Dive duration was the best predictor of foraging, with dives >400.6 seconds classified as foraging, and a 96% classification accuracy. There were no diurnal patterns in foraging depth or rates and average duration of bouts was 2.94 hours with maximum bout durations lasting up to 14 hours. The results indicated that pilot whales forage in relatively long bouts and the ADLB indicate that pilot whales rarely, if ever exceed their aerobic limits. To evaluate the response to predators I used controlled playback experiments to examine the behavioral responses of 10 of the tagged short-finned pilot whales off Cape Hatteras, North Carolina and 4 Risso’s dolphins (Grampus griseus) off Southern California to the calls of mammal-eating killer whales (MEK). Both species responded to a subset of MEK calls with increased movement, swim speed and increased cohesion of the focal groups, but the two species exhibited different directional movement and vocal responses. Pilot whales increased their call rate and approached the sound source, but Risso’s dolphins exhibited no change in their vocal behavior and moved in a rapid, directed manner away from the source. Thus, at least to a sub-set of mammal-eating killer whale calls, these two study species reacted in a manner that is consistent with their patterns of social organization. Pilot whales, which live in relatively permanent groups bound by strong social bonds, responded in a manner that built on their high levels of social cohesion. In contrast, Risso’s dolphins exhibited an exaggerated flight response and moved rapidly away from the sound source. The fact that both species responded strongly to a select number of MEK calls, suggests that structural features of signals play critical contextual roles in the probability of response to potential threats in odontocete cetaceans.

Identifying knowledge gaps in seagrass research and management: An Australian perspective.

Seagrass species form important marine and estuarine habitats providing valuable ecosystem services and functions. Coastal zones that are increasingly impacted by anthropogenic development have experienced substantial declines in seagrass abundance around the world. Australia, which has some of the world's largest seagrass meadows and is home to over half of the known species, is not immune to these losses. In 1999 a review of seagrass ecosystems knowledge was conducted in Australia and strategic research priorities were developed to provide research direction for future studies and management. Subsequent rapid evolution of seagrass research and scientific methods has led to more than 70% of peer reviewed seagrass literature being produced since that time. A workshop was held as part of the Australian Marine Sciences Association conference in July 2015 in Geelong, Victoria, to update and redefine strategic priorities in seagrass research. Participants identified 40 research questions from 10 research fields (taxonomy and systematics, physiology, population biology, sediment biogeochemistry and microbiology, ecosystem function, faunal habitats, threats, rehabilitation and restoration, mapping and monitoring, management tools) as priorities for future research on Australian seagrasses. Progress in research will rely on advances in areas such as remote sensing, genomic tools, microsensors, computer modeling, and statistical analyses. A more interdisciplinary approach will be needed to facilitate greater understanding of the complex interactions among seagrasses and their environment.

Genetic Structure of the Florida Key Tree Cactus, Pilosocereus robinii, using Restriction Site associated DNA (RAD) markers

Rare plant conservation efforts must utilize current genetic methods to ensure the evolutionary potential of populations is preserved. One such effort involves the Key Tree Cactus, Pilosocereus robinii, which is an endangered columnar cactus native to the Florida Keys. The populations have precipitously declined over the past decade because of habitat loss and increasing soil salinity from rising sea levels and storm surge. Next-generation DNA sequencing was used to assess the genetic structure of the populations. Twenty individuals representative of both wild and extirpated cacti were chosen for Restriction Site Associated DNA (RAD) analysis. Samples processed using the HindIII and NotIII restriction enzymes produced 82,382,440 high quality reads used for genetic mapping, from which 5,265 Single Nucleotide Polymorphisms (SNPs) were discovered. The analysis revealed that the Keys’ populations are closely related with little population differentiation. In addition, the populations display evidence of inbreeding and low genetic diversity.

Life history of a wide-ranging deepwater lantern shark in the north-east Atlantic, Etmopterus spinax (Chondrichthyes: Etmopteridae), with implications for conservation

In this paper, the population biology of the velvet belly lanternshark Etmopterus spinax was studied and life-history coefficients determined. Age was estimated from sections of the second dorsal spine and validated by marginal increment analysis. Males attained a maximum age of 8 years while 11 year-old females were found. Several growth models were fitted and compared for both size-at-age and mass-at-age data, showing that even though this is a small-sized species, it has a relatively slow growth rate. This species matures late, specifically at 49.6 and 42.5% of the maximum observed ages for males and females, respectively. It has a low fecundity, with a mean ovarian fecundity of 9.94 oocytes and a mean uterine fecundity of 7.59 embryos per reproductive cycle. This species seems to have a long reproductive cycle, and even though no conclusive data were obtained, a 2-3 year cycle is possible. The estimated coefficients indicate that this species has a vulnerable life cycle, typical of deepwater squalid sharks. Given the high fishing pressures that it is suffering in the north-east Atlantic, this fish may already be facing severe declines or in risk of facing them in the near future. (C) 2008 The Authors Journal compilation (C) 2008 The Fisheries Society of the British Isles

The biology of an isolated population of American Flamingo Phoenicopterus ruber in the Galapagos Islands

A genetically and morphologically divergent population of c.500 American Flamingos, isolated from the parental Caribbean stock of Phoenicopterus ruber, occurs in the Galapagos archipelago. Based primarily on data from a 3-year study, we provide the first description of the feeding and breeding biology of this population. Galapagos provides a suitable habitat comprising lagoons on a number of islands, among which the flamingos travel in response to food and nest site availability. The occurrence and qualnity of some food species was associated with the chlorosity of lagoon water, as was the distribution of flamingos. They bred opportunistically at five lagoons on four islands, sometimes simultaneously on more than one island. Group display usually involved approx 20 birds and colonies contained as few as three nests. Laying occurred during nine months of the year... We review potential dangers to this unique population and suggest conservation measures.

Negligible evidence for regional genetic population structure for two shark species Rhizoprionodon acutus (Rüppell, 1837) and Sphyrna lewini (Griffith & Smith, 1834) with contrasting biology

Biodiversity of sharks in the tropical Indo-Pacific is high, but species-specific information to assist sustainable resource exploitation is scarce. The null hypothesis of population genetic homogeneity was tested for scalloped hammerhead shark (Sphyrna lewini, n = 237) and the milk shark (Rhizoprionodon acutus, n = 207) from northern and eastern Australia, using nuclear (S. lewini, eight microsatellite loci; R. acutus, six loci) and mitochondrial gene markers (873 base pairs of NADH dehydrogenase subunit 4). We were unable to reject genetic homogeneity for S. lewini, which was as expected based on previous studies of this species. Less expected were similar results for R. acutus, which is more benthic and less vagile than S. lewini. These features are probably driving the genetic break found between Australian and central Indonesian R. acutus (F-statistics; mtDNA, 0.751–0.903, respectively; microsatellite loci, 0.038–0.047 respectively). Our results support the spatially homogeneous monitoring and management plan for shark species in Queensland, Australia.

Aspects of the biology and population dynamics of freshwater mussels in Lake Kariba and Lake McIlwaine

The essential aim of this study was to provide a broad foundation of biological knowledge upon which a programme of mussel utilization and management could be built. Results of the study are presented in three main sections. Part 1 describes the stock of Lake Kariba and Lake McIlwaine; part 2 describes various aspects of the breeding biology of the three species; and part 3 presents the results of morphological, biochemical and age analyses - aspects which are used for initial standing crop and production calculations. The final discussion concludes the thesis with a general examination in ecological terms of the factors which have influenced the development and nature of the mussel faunas of the two lakes under consideration.