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661.
Oliver Manlik Robert C. Lacy William B. Sherwin Hugh Finn Neil R. Loneragan Simon J. Allen 《Conservation biology》2022,36(4):e13897
Human-caused mortality of wildlife is a pervasive threat to biodiversity. Assessing the population-level impact of fisheries bycatch and other human-caused mortality of wildlife has typically relied upon deterministic methods. However, population declines are often accelerated by stochastic factors that are not accounted for in such conventional methods. Building on the widely applied potential biological removal (PBR) equation, we devised a new population modeling approach for estimating sustainable limits to human-caused mortality and applied it in a case study of bottlenose dolphins affected by capture in an Australian demersal otter trawl fishery. Our approach, termed sustainable anthropogenic mortality in stochastic environments (SAMSE), incorporates environmental and demographic stochasticity, including the dependency of offspring on their mothers. The SAMSE limit is the maximum number of individuals that can be removed without causing negative stochastic population growth. We calculated a PBR of 16.2 dolphins per year based on the best abundance estimate available. In contrast, the SAMSE model indicated that only 2.3–8.0 dolphins could be removed annually without causing a population decline in a stochastic environment. These results suggest that reported bycatch rates are unsustainable in the long term, unless reproductive rates are consistently higher than average. The difference between the deterministic PBR calculation and the SAMSE limits showed that deterministic approaches may underestimate the true impact of human-caused mortality of wildlife. This highlights the importance of integrating stochasticity when evaluating the impact of bycatch or other human-caused mortality on wildlife, such as hunting, lethal control measures, and wind turbine collisions. Although population viability analysis (PVA) has been used to evaluate the impact of human-caused mortality, SAMSE represents a novel PVA framework that incorporates stochasticity for estimating acceptable levels of human-caused mortality. It offers a broadly applicable, stochastic addition to the demographic toolbox to evaluate the impact of human-caused mortality on wildlife. 相似文献
662.
Constitutive and induced defenses to herbivory in above- and belowground plant tissues 总被引:3,自引:0,他引:3
A recent surge in attention devoted to the ecology of soil biota has prompted interest in quantifying similarities and differences between interactions occurring in above- and belowground communities. Furthermore, linkages that interconnect the dynamics of these two spatially distinct ecosystems are increasingly documented. We use a similar approach in the context of understanding plant defenses to herbivory, including how they are allocated between leaves and roots (constitutive defenses), and potential cross-system linkages (induced defenses). To explore these issues we utilized three different empirical approaches. First, we manipulated foliar and root herbivory on tobacco (Nicotiana tabacum) and measured changes in the secondary chemistry of above- and belowground tissues. Second, we reviewed published studies that compared levels of secondary chemistry between leaves and roots to determine how plants distribute putative defense chemicals across the above- and belowground systems. Last, we used meta-analysis to quantify the impact of induced responses across plant tissue types. In the tobacco system, leaf-chewing insects strongly induced higher levels of secondary metabolites in leaves but had no impact on root chemistry. Nematode root herbivores, however, elicited changes in both leaves and roots. Virtually all secondary chemicals measured were elevated in nematode-induced galls, whereas the impact of root herbivory on foliar chemistry was highly variable and depended on where chemicals were produced within the plant. Importantly, nematodes interfered with aboveground metabolites that have biosynthetic sites located in roots (e.g., nicotine) but had the opposite effect (i.e., nematodes elevated foliar expression) on chemicals produced in shoots (e.g., phenolics and terpenoids). Results from our literature review suggest that, overall, constitutive defense levels are extremely similar when comparing leaves with roots, although certain chemical classes (e.g., alkaloids, glucosinolates) are differentially allocated between above- and belowground parts. Based on a meta-analysis of induced defense studies we conclude that: (1) foliar induction generates strong responses in leaves, but much weaker responses in roots, and (2) root induction elicits responses of equal magnitude in both leaves and roots. We discuss the importance of this asymmetry and the paradox of cross-system induction in relation to optimal defense theory and interactions between above- and belowground herbivory. 相似文献
663.
Pringle RM 《Ecology》2008,89(1):26-33
Ecologists increasingly recognize the ability of certain species to influence ecological processes by engineering the physical environment, but efforts to develop a predictive understanding of this phenomenon are in their early stages. While many believe that the landscape-scale effects of ecosystem engineers will be to increase habitat diversity and therefore the abundance and richness of other species, few generalities exist about the effects of engineering at the scale of the engineered patch. According to one hypothesis, activities that increase structural habitat complexity within engineered patches will have positive effects on the abundance or diversity of other organisms. Here I show that, by damaging trees and increasing their structural complexity, browsing elephants create refuges used by a common arboreal lizard. Observational surveys and a lizard transplant experiment revealed that lizards preferentially occupy trees with real or simulated elephant damage. A second experiment showed that lizards vacate trees when elephant-engineered refuges are removed. Furthermore, local lizard densities increased with (and may be constrained by) local densities of elephant-damaged trees. This facilitative effect of elephants upon lizards via patch-scale habitat modification runs contrary to previously documented negative effects of the entire ungulate guild on lizards at the landscape scale, suggesting that net indirect effects of large herbivores comprise opposing trophic and engineering interactions operating at different spatial scales. Such powerful megaherbivore-initiated interactions suggest that anthropogenic changes in large-mammal densities will have important cascading consequences for ecological communities. 相似文献
664.
We show that a higher vertebrate can graze surficial intertidal biofilm, previously only considered a food source for rasping invertebrates and a few specialized fish. Using evidence from video recordings, stomach contents, and stable isotopes, we describe for the first time the grazing behavior of Western Sandpipers (Calidris mauri) and estimate that biofilm accounts for 45-59% of their total diet or 50% of their daily energy budget. Our finding of shorebirds as herbivores extends the trophic range of shorebirds to primary consumers and potential competitors with grazing invertebrates. Also, given individual grazing rates estimated at seven times body mass per day and flock sizes into the tens of thousands, biofilm-feeding shorebirds could have major impacts on sediment dynamics. We stress the importance of the physical and biological processes maintaining biofilm to shorebird and intertidal conservation. 相似文献
665.
Given recent focus on large rivers as conduits for excess nutrients to coastal zones, their role in processing and retaining nutrients has been overlooked and understudied. Empirical measurements of nutrient uptake in large rivers are lacking, despite a substantial body of knowledge on nutrient transport and removal in smaller streams. Researchers interested in nutrient transport by rivers (discharge >10000 L/s) are left to extrapolate riverine nutrient demand using a modeling framework or a mass balance approach. To begin to fill this knowledge gap, we present data using a pulse method to measure inorganic nitrogen. (N) transport and removal in the Upper Snake River, Wyoming, USA (seventh order, discharge 12000 L/s). We found that the Upper Snake had surprisingly high biotic demand relative to smaller streams in the same river network for both ammonium (NH4+) and nitrate (NO3-). Placed in the context of a meta-analysis of previously published nutrient uptake studies, these data suggest that large rivers may have similar biotic demand for N as smaller tributaries. We also found that demand for different forms of inorganic N (NH4+ vs. NO3-) scaled differently with stream size. Data from rivers like the Upper Snake and larger are essential for effective water quality management at the scale of river networks. Empirical measurements of solute dynamics in large rivers are needed to understand the role of whole river networks (as opposed to stream reaches) in patterns of nutrient export at regional and continental scales. 相似文献
666.
Gilad Heinisch Aldo Corriero Antonio Medina Francisco J. Abascal Jose-Miguel de la Serna Robert Vassallo-Agius Antonio Belmonte Ríos Antonio García Fernando de la Gándara Christian Fauvel Christopher R. Bridges Constantinos C. Mylonas Saadet F. Karakulak Isik Oray Gregorio De Metrio Hanna Rosenfeld Hillel Gordin 《Marine Biology》2008,154(4):623-630
Atlantic bluefin tuna (BFT; Thunnus thynnus) is a migrating species straddling the North Atlantic Ocean and Mediterranean Sea. It is assumed that this species is divided
into a western and an eastern stock, which spawn in the Gulf of Mexico and the Mediterranean Sea, respectively. To learn more
about the reproductive behavior of the eastern BFT stock, we tracked gonadal development in adult fish that were sampled between
April and July during three consecutive years (2003–2005). Sampling campaigns were carried out using common fishing methods
at selected locations within the Mediterranean Sea, namely Levantine Sea, Malta, and Balearic Islands. An additional sampling
point, Barbate, was situated northwest of the Straits of Gibraltar along the Atlantic coast. Morphometric parameters such
as the total body mass (M
B) and the weights of the gonads (M
G) were recorded, and the respective gonadosomatic index (GSI) values were calculated. The data collected revealed two important
trends: (1) GSI values are higher in fish caught in the eastern rather than the western locations across the Mediterranean
Sea, and (2) the GSI reaches maximum values between late May and early June in Levantine Sea (eastern Mediterranean Sea),
and only 2 and 4 weeks later in the central (Malta) and western (Balearic Islands) locations, respectively. The advanced gonadal
development in BFT correlates well with higher sea surface temperatures. Our findings also distinguish the northern Levantine
Sea BFT population (mean M
B 78.41 ± 4.13 kg), and the Barbate BFT population with the greatest M
B (all fish sampled > 100 kg). These data reflect a situation in which the eastern Mediterranean basin may function as a habitat
for young BFT, until they gain a larger M
B and are able to move to the Atlantic Ocean. However, the existence of genetically discrete BFT populations in the Mediterranean
Sea cannot be ruled out. 相似文献
667.
David F. Staples Mark L. Taper Brian Dennis Robert J. Boik 《Environmental and Ecological Statistics》2009,16(4):547-560
Estimates of a population’s growth rate and process variance from time-series data are often used to calculate risk metrics
such as the probability of quasi-extinction, but temporal correlations in the data from sampling error, intrinsic population
factors, or environmental conditions can bias process variance estimators and detrimentally affect risk predictions. It has
been claimed (McNamara and Harding, Ecol Lett 7:16–20, 2004) that estimates of the long-term variance that incorporate observed
temporal correlations in population growth are unaffected by sampling error; however, no estimation procedures were proposed
for time-series data. We develop a suite of such long-term variance estimators, and use simulated data with temporally autocorrelated
population growth and sampling error to evaluate their performance. In some cases, we get nearly unbiased long-term variance
estimates despite ignoring sampling error, but the utility of these estimators is questionable because of large estimation
uncertainty and difficulties in estimating correlation structure in practice. Process variance estimators that ignored temporal
correlations generally gave more precise estimates of the variability in population growth and of the probability of quasi-extinction.
We also found that the estimation of probability of quasi-extinction was greatly improved when quasi-extinction thresholds
were set relatively close to population levels. Because of precision concerns, we recommend using simple models for risk estimates
despite potential biases, and limiting inference to quantifying relative risk; e.g., changes in risk over time for a single
population or comparative risk among populations. 相似文献
668.
Simon Anthony Morley Koh Siang Tan Robert W. Day Stephanie M. Martin Hans-O. Pörtner Lloyd S. Peck 《Marine Biology》2009,156(10):1977-1984
The upper thermal limits for burrowing and survival were compared with micro-habitat temperature for anomalodesmatan clams:
Laternula elliptica (Antarctica, 67°S); Laternula recta, (temperate Australia, 38°S) and Laternula truncata (tropical Singapore, 1°N). Lethal limits (LT50) were higher than burrowing limits (BT50) in L. elliptica (7.5–9.0 and 2.2°C) and L. recta (winter, 32.8–36.8 and 31.1–32.8°C) but the same range for L. truncata (33.0–35.0 and 33.4–34.9°C). L. elliptica and L. truncata had a BT50 0.4 and 2.4–3.9°C, respectively, above their maximum experienced temperature. L. recta, which experience solar heating during midday low tides, had a BT50 0.7–2.4°C below and a range for LT50 that spanned their predicted environmental maximum (33.5°C). L. recta showed no seasonal difference in LT50 or BT50. Our single genus comparisons contrast with macrophysiological studies showing that temperate species cope better with elevated
temperatures.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
669.
Honey bee foragers specialize on collecting pollen and nectar. Pollen foraging behavior is modulated by at least two stimuli
within the nest: the presence of brood pheromone and young larvae and the quantity of stored pollen. Genetic variation in
pollen foraging behavior has been demonstrated repeatedly. We used selected high and low pollen-hoarding strains of bees that
differ dramatically in the quantity of pollen collected to determine if the observed differences in foraging could be explained
by differential responses to brood stimuli. Workers from the high and low pollen-hoarding strains and wild-type bees were
co-fostered in colonies with either brood or no brood. As expected based on previous studies, returning high pollen-hoarding
foragers collected heavier pollen loads and lighter nectar loads than low pollen-hoarding bees. Effects of brood treatment
were also observed; bees exposed to brood collected heavier pollen loads and initiated foraging earlier than those from broodless
colonies. More specifically, brood treatment resulted in increased pollen foraging in high pollen-hoarding bees but did not
affect pollen foraging in low pollen-hoarding bees, suggesting that high pollen-hoarding bees are more sensitive to the presence
of brood. However, response to brood stimuli does not sufficiently explain the differences in foraging behavior between the
strains since these differences persisted even in the absence of brood. 相似文献
670.
Comparative Toxicity of PCBs and PBDEs Using Human Cancer Cell Lines and Zebrafish Embryos 总被引:2,自引:1,他引:1
SHEN Hua-ping HUANG Chang-jiang LU Fang YANG Jun-hu TANGUAY Robert SUN Lu-zhe DONG Qiao-xiang 《生态毒理学报》2009,4(5):625-633
研究了6种多氯联苯(PCBs)3,3′,4,4′-四氯联苯(PCB77)、2,3,3′,4,4′-五氯联苯(PCB105)、2,3′,4,4′,5-五氯联苯(PCB118)、3,3′,4,4′,5-五氯联苯(PCB126)、2,3,3',4,4',5-六氯联苯(PCB156)和商业型混合多氯联苯Aroclor1254,两种多溴联苯醚(PBDEs)2,2′,4,4′-四溴二苯醚(PBDE47)、十溴二苯醚(PBDE209)对人类癌细胞生长和斑马鱼脱膜与不脱膜胚胎发育的影响.8种化合物均使用0.01、0.1、1.0、10μmol·L-14个浓度进行1~6d的暴露实验.结果表明,PBDE209在最高浓度10μmol·L-1下对结肠癌细胞HCT116(暴露3d后)和RKO(暴露5d后)具有显著的生长抑制作用,所有化合物均对乳腺癌细胞没有显著影响.相比之下,化合物对受精后5~6h(5~6hpf)的斑马鱼胚胎的毒性效应显得比较明显,而各化合物对胚胎的致畸和致死效应又不相同,其毒性强弱依次为PCB126≈PCB156>PCB1254(Aroclor1254)>PBDE47>PCB77>PCB105≈PCB118≈PBDE209.其中PBDE209在未脱膜暴毒后均无致畸与致死现象,脱膜暴毒后最高浓度才表现出显著意义的致畸作用,而PBDE47在最高浓度下可产生高达80%的致畸率,这说明胚胎绒毛膜具有有效阻挡大分子物质如PBDE209进入的作用.PCBs的毒性效应与其空间结构密切相关.如PCB126和PCB105具有相同的分子式,前者在1μmol·L-1下就引起了显著的致死和致畸效应,而后者即使在10μmol·L-1下也没有显著的效应.实验结果也说明不同类型的实验对象所展示的毒性效应并不相同,化合物对体外培养的细胞和发育中的胚胎具有不同的影响. 相似文献