Decline In Abundance Research Articles

Influence of Canopy Cover and Meteorological Factors on the Abundance of Bark and Ambrosia Beetles (Coleoptera: Curculionidae) in Avocado Orchards Affected by Laurel Wilt

In the last decade in South Florida, approximately 200,000 avocado trees have succumbed to laurel wilt (LW), a fungal disease vectored by ambrosia beetles. Sanitation (e.g., pruning, stumping, and removal of LW–affected trees) and replanting with young trees are cultural practices currently used by avocado growers to reduce the incidence of LW. Surveillance in these managed orchards suggests a decline in ambrosia beetle abundance, and previous research determined that female flight activity is influenced by light intensity. Therefore, we investigated the effect of three canopy covers (i.e., full canopy, topworked, and new planting) on ambrosia beetle abundance. A total of 28,184 individuals, representing 15 species within Scolytinae and Platypodinae, were captured passively in three LW–affected avocado orchards over a one-year period. Full canopy cover exhibited the highest number of beetles and the lowest light intensity. The opposite was found for topworked and new planting covers. Additionally, we documented the effect of meteorological factors on the flight dispersal of five species known to vector the LW pathogen. The flight activity of Xylosandrus crassiusculus and Xyleborinus saxesenii was highly influenced by abiotic factors (R2 > 0.50), especially solar radiation, whereas the flight of Xyleborus affinis, Xyleborus volvulus, and Xyleborus bispinatus was only partially explained by climatic variables (0.20 < R2 < 0.30). Our results indicate that reducing canopy cover, thereby increasing light intensity, suppresses ambrosia beetle abundance, especially for species associated with the LW pathogen. Abiotic factors play a critical role in the dispersal of invasive species (X. crassiusculus and X. saxesenii), but their effect is less pronounced on native species (X. affinis, X. volvulus, and X. bispinatus). Canopy management alters the microclimatic conditions in avocado orchards, affecting ambrosia beetle abundance and flight activity.

Impact of resuspended mine tailings on benthic biodiversity and ecosystem processes: The case study of Portmán Bay, Western Mediterranean Sea, Spain

Industrial seabed mining is expected to cause significant impacts on marine ecosystems, including physical disturbance and the generation of plumes of toxin-laden water. Portmán Bay (NW Mediterranean Sea), where an estimated amount of 60 Mt of mine tailings from sulphide ores were dumped from 1957 to 1990, is one of the most metal-polluted marine areas in Europe and worldwide. This bay can be used to assess the impact on marine ecosystems of particle settling from sediment plumes resulting from mine tailings resuspension. With this purpose in mind, we conducted a field experiment there to investigate subsequent effects of deposition of (artificially resuspended) contaminated sediments on (i) prokaryotic abundance and meiofaunal assemblages (in terms of abundance and diversity), (ii) the availability of trophic resources (in terms of organic matter biochemical composition), and (iii) a set of ecosystem functions including meiofaunal biomass, heterotrophic C production and C degradation rates. The results of this study show that mine tailings resuspension and plume deposition led to the decline of prokaryotic abundance and nematode's biodiversity. The later decreased because of species removal and transfer along with particle resuspension and plume deposition. Such changes were also associated to a decrease of the proteins content in the sediment organic matter, faster C degradation rates and higher prokaryotic C production. Overall, this study highlights that mine tailing resuspension and ensuing particle deposition can have deleterious effects on both prokaryotes and nematode diversity, alter biogeochemical cycles and accelerate C degradation rates. These results should be considered for the assessment of the potential effects of seabed mineral exploitation on marine ecosystems at large.

Assessment of Australian Sea Lion Bycatch Mortality in a Gillnet Fishery, and Implementation and Evaluation of an Effective Mitigation Strategy

Globally, the bycatch of marine mammals in fisheries represents the greatest source of human-caused mortality that threatens the sustainability of many populations and species. The Australian sea lion (Neophoca cinerea) is an endangered species, whose populations off South Australia (SA) have been subject to bycatch in a demersal gillnet fishery targeting sharks since the 1960s. A comprehensive assessment was undertaken of sea lion bycatch mortality that combined independent fishery observer data with species distribution models (underpinned by satellite tracking, abundance data and population modeling) to model the relationship between at-sea foraging effort and bycatch rate. Combined with the distribution of fishing effort, these models enabled the overall level of bycatch mortality to be estimated by age, sex and subpopulation, facilitating population viability analyses that indicated most subpopulations were declining, and subject to unsustainable levels of bycatch mortality. To reduce this mortality, the Australian Fisheries Management Authority implemented an Australian Sea Lion Management Strategy that included an independent observer program (ultimately 100% electronic monitoring of gillnet fishing off SA), permanent spatial gillnet closures around all sea lion breeding sites, bycatch mortality limits that triggered temporal (18 months) spatial closures when zone-specific bycatch trigger limits were reached, and incentives for gillnet fishers to switch to an alternate fishing method (longlines). The Strategy had immediate impacts on the fishery: it resulted in significant reductions in gillnet fishing effort and on the reported bycatch of sea lions. In the next decade, there was an estimated 98% reduction in sea lion bycatch mortality from gillnet interactions and an apparent stabilization of the decline in sea lion pup abundances at some impacted breeding sites. There was an almost complete transition in the fishery from gillnets to longlines, and fishing catches returned to pre-management levels. The successful implementation of management measures to mitigate sea lion bycatch mortality in the gillnet fishery off SA was rapid, science informed, adaptive, comprehensive, and backed by strong compliance and monitoring of the fishery. It provides an important case study which demonstrates how management measures can be effectively applied to mitigate bycatch mortality of marine mammals and other marine protected species.

Abundance and Foraging Behaviour of Entomophilous Pollinators on Sesame, Sesamum indicum L.

The present study focused on the community of insect pollinators, abundance and foraging behavior of different pollinators on sesame. During the study period 32 species of insect visitors were observed in sesame. The order Hymenoptera shared maximum abundance (81.25 %) followed by Diptera (12.50 %) and Coleoptera (6.25 %). Among them acted as dominant forager contributing 24.72% Apis dorsata followed by (22.44%) and (11.29%) Most of the bees visited sesame flowers, but the density of Apis cerana indica Apis florea . A. dorsata, A. c. indica was maximum and peaked during 1000- 1200 hours with a mean population of 14.06 and 12.0 individuals / m / 5 min whereas the activity 2of peaked (7.05 individuals/ m / 5 min) at 0800-1000 hours and a steady decline in abundance of bees was observed during evening A. florea 2 hours. The flower visitation frequency was found maximum (9.14 flowers/ min) in followed by (7.44 flowers/ min) during A. c. indica A. dorsata 1000- 1200 hours meanwhile the sequence of flower visitation reduces during evening 1600-1800 hours as 3.12 and 3.18 flowers/ min respectively. The time spent by different bees was in the order (18.05 sec/ flower) > (15.04 sec/flower) > (11.14 A. florea A. cerana A. dorsata sec/ flower) between 0600-0800 hours.

Rapid population decline in one of the last recruiting populations of the endangered Clanwilliam sandfish (Labeo seeberi): The roles of climate change and non‐native fish

Abstract Freshwater fish are in decline worldwide as a result of introduced non‐native species, impoundment, water quality changes, over‐abstraction, and climate change. The Clanwilliam sandfish Labeo seeberi is an endangered migratory cyprinid endemic to a single river system in South Africa's Cape Fold Ecoregion. It has declined across its range and persists as fragmented populations in the Doring River system. One of the last recruiting populations occurs in the Oorlogskloof River, where three non‐native fish species are present: smallmouth bass Micropterus dolomieu, bluegill sunfish Lepomis macrochirus (both alien and invasive), and banded tilapia Tilapia sparrmanii (extralimital). Impacts of these non‐natives, together with climate change, may pose a serious threat to this important sandfish population and to other cohabiting native fish species. A 6 year data set, collected over 9 years and spanning 25 km of the Oorlogskloof River, was analysed to characterize spatio‐temporal variation in sandfish abundance and size structure and to evaluate the relative impacts of biotic and abiotic factors on population trends. Sandfish experienced a 92.6% decline in relative abundance from 2013 to 2018, driven by a 99.6% decline in young‐of‐the‐year individuals. A combination of extreme rainfall events and drought appear to have played a key role in the decline and subsequently prevented recovery. Small sandfish (≤200 mm) were almost entirely absent from the centrarchid‐invaded section of the Oorlogskloof but were relatively abundant where these centrarchids were absent, suggesting a strong adverse impact of these non‐native species. Banded tilapia co‐occurred with sandfish without any apparent adverse impacts on the relative abundance or size structure of sandfish. Improved water resource management and preventing the further spread of non‐natives must be conservation priorities. Localized eradication of non‐native species must also be considered to reclaim habitat and restore connectivity. Translocations may be required to prevent species extinctions.

Seasonal and interannual variations of the abundance of the dinoflagellate Noctiluca scintillans in the northern Black Sea

ABSTRACT Noctiluca scintillans (Macartney) Kofoid and Swezy, 1921 contributes ∼ 85% of the total biomass of heterotrophic plankton in Crimean coastal waters. Data for the retrospective analysis come from a 20-year sampling (in 2000s) across the Crimean shelf and in adjacent open sea waters. Samples were collected onboard research vessels, in the upper 150 m layer, by Juday nets (vertical hauls) fitted with 145 µm mesh. These data were compared to field surveys of the 1960s. Seasonal blooms of Noctiluca were pronounced during summer time, with the peak of abundance in June. The mesoscale spatial distribution of Noctiluca abundance was most heterogeneous in June as well. The annual concentration of cells in coastal waters exceeded that of the open sea by four times. The coefficient of Noctiluca seasonal abundance variation in coastal waters was 1.5 times higher than that of the open sea. The Principal Component Analysis implied that the seasonal variation of the Noctiluca abundance offshore was modulated by coupling of the atmospheric precipitation, sea surface temperature, photosynthetically active radiation, euphotic depth, chlorophyll-a concentration, Noctiluca abundance in coastal waters, mesoscale eddies and wind stress. A general decline of Noctiluca abundance and biomass was observed in coastal waters, from the 1960s to the present.

Assessment of the biota condition of the Specially Protected Natural Territory “Sosnovaya Rosha” in the vicinity of a multi-lane road under construction

The article presents the results of a reconnaissance assessment of the state of biota in the area of the highway of Specially Protected Natural Territory “Sosnovaya Rosha” under construction in the city of Yoshkar-Ola (Republic of Mari El, Russia). The studied plant communities, especially mixed forests, in the forest park are characterized by a rather considerable diversity. A decrease in vitality was recorded in coniferous trees caused by low-quality drainage works. Assessment of environmental quality by IFA of the lamina of B. pendula trees has shown reasonably favorable conditions. All reservoirs are characterized by a high abundance of invertebrates. Currently, no sharp decline in the abundance of pedobionts have been noted. The diversity of dendrobiont insects with low abundance and the optimal ratio of phytophagous to predatory insects may indicate stable relationships between consorts and the determinant, a tree species. The distribution of amphibians and reptiles in the SPNT has mosaic character. We have also noted trends toward a decrease in species diversity and populations density of ornithofauna. At the moment, the road is not open for transport yet, and no sharp decline in species diversity or abundance of individuals in populations is observed.

Assessment of Fish Abundance, Biodiversity and Movement Periodicity Changes in a Large River over a 20-Year Period

A river is an ecosystem where fish fauna represents an important structural element. To re-establish connectivity, it is imperative to allow movement between functional habitats. Due to the hydromorphological complexity of large anthropized rivers and the lack of study techniques that can be used in such environments, relevant data with regard to fish ecology are scarce. On the River Meuse, Belgium, at a point 323 km upstream from the North Sea, the Lixhe hydroelectric dam is equipped with two fishways. Both were continuously monitored using capture traps for 20 consecutive years (from 1999 to 2018), representing 4151 monitoring events. The objectives of the present study were to describe the overall abundance and movement indicators of mainly holobiotic potamodromous fish species and to analyse their temporal evolution. We captured 388,631 individuals (n = 35 fish species) during the 20 years of fishway monitoring; 22.7% were adults (>75% of which were cyprinids), and 83.3% juveniles (>90% cyprinids). From 1999 to 2018, the results showed a drastic reduction in yearly captures for some native species as well as the apparent emergence of non-native (e.g., Silurus glanis) and reintroduced species (e.g., Salmo salar). The annual capture periodicities associated with environmental factors were clearly defined and were mostly related to the spring spawning migration of the adult stage. This long-term monitoring demonstrated how the fishways are used by the whole fish community and allowed a better understanding of their movement ecology in a large lowland anthropized river. The appearance of non-native species and the drastic decline in abundance of some common and widespread European fish should prompt river managers to adopt conservation measures.

Southeast Alaskan kelp forests: inferences of process from large-scale patterns of variation in space and time.

Humans were considered external drivers in much foundational ecological research. A recognition that humans are embedded in the complex interaction networks we study can provide new insight into our ecological paradigms. Here, we use time-series data spanning three decades to explore the effects of human harvesting on otter–urchin–kelp trophic cascades in southeast Alaska. These effects were inferred from variation in sea urchin and kelp abundance following the post fur trade repatriation of otters and a subsequent localized reduction of otters by human harvest in one location. In an example of a classic trophic cascade, otter repatriation was followed by a 99% reduction in urchin biomass density and a greater than 99% increase in kelp density region wide. Recent spatially concentrated harvesting of otters was associated with a localized 70% decline in otter abundance in one location, with urchins increasing and kelps declining in accordance with the spatial pattern of otter occupancy within that region. While the otter–urchin–kelp trophic cascade has been associated with alternative community states at the regional scale, this research highlights how small-scale variability in otter occupancy, ostensibly due to spatial variability in harvesting or the risk landscape for otters, can result in within-region patchiness in these community states.

Reduction effect of individual N, P, K fertilization on antibiotic resistance genes in reclaimed water irrigated soil

The transfer of antibiotic resistance genes (ARGs) in soil under reclaimed water irrigation poses a potential environmental risk. Regulation of NPK fertilizer could influence the behavior of bacterial communities, mobile genetic elements (MGEs), and soil properties, which determine the fate of ARGs. To identify the key element in NPK fertilizer and realize efficient regulation, we explored the effect of individual N, P, K fertilization on ARG variation in tomato rhizosphere and bulk soils. Compared with an unfertilized treatment, N fertilization resulted in greater decreases in the abundance of ARGs (decreases of 24.06%–73.09%) than did either P fertilization (increases of up to 35.84%, decreases of up to 58.80%) or K fertilization (decreases of 13.47%–72.47%). The influence of different forms of N (CO(NH2)2, NaNO3, and NH4HCO3), P (Ca(H2PO4)2 and CaMgO4P+), and K (KCl and K2(SO4)) fertilizers was also investigated in this study, and showed the influence of NaNO3, CaMgO4P+, and K2(SO4) on reducing ARGs abundance was greater in different types of N, P, K fertilizers. Bacterial communities showed the strongest response to N fertilization. The reduced bacterial diversity and abundance of ARG-host and non-host organisms explained the decline of total ARG abundance in soil. In soils fertilized with either P or K, the effect of soil properties, especially total nitrogen and pH, on ARG variation was greater than that of bacterial community and MGEs. These results suggest that N regulation of in NPK fertilizer may be an effective way to reduce the risks of ARGs in soil associated with reclaimed water irrigation.

Complex effects of acidification, habitat properties and fish stock on littoral macroinvertebrate assemblages in montane standing waters

Littoral macroinvertebrates in acidified waterbodies are affected by the interaction of acidification and local environmental conditions. Understanding the interplay of these factors in the structuring of communities is essential for interpreting responses to and/or recovery from acidification. Here, we analyse the species composition and richness of littoral macroinvertebrates in a range of acidified montane standing waters in relation to water chemistry, littoral characteristics and fish stock. The main species composition gradients were related to pH and conductivity; however, considerable variation along these gradients was associated with local habitat characteristics (changing water levels and littoral structure) and concentration of ionic aluminium and dissolved organic carbon. Although fish stock effects were confounded by correlated acidity, we observed a significant decline in abundance of macroinvertebrates vulnerable to fish predation at sites with fish stock. Overall, littoral macroinvertebrates of acidic waterbodies were diverse due to the heterogeneity of local habitat properties, despite they were dominated by acid-tolerant species. Acidic humic sites with dense, heterogeneous littoral vegetation were species-rich, hosting numerous habitat specialists and rare species, while chronically acidified lakes with high aluminium concentrations and sparse littoral vegetation had species-poor assemblages, characteristic of strong acid-stress. Water level manipulation resulted in serious assemblage impoverishment, overriding the effects of more favourable water chemistry. This study shows that the littoral fauna of acidic waterbodies is structured by complex effects induced by local factors in addition to acidity, resulting in acid-stressed assemblages with relatively high variability, emphasising a need to analyse local habitat factors when evaluating the impact of acidification on macroinvertebrates.

Native Fish Need A Natural Flow Regime

Water development has threatened the ecological integrity of riverine ecosystems. Increasing water demand, persistent drought, and climate change exacerbate the effects of habitat degradation and loss in altered systems such as the Colorado River basin. Today, biologists are challenged to identify management actions that benefit native fishes while not hindering water development or management. Herein, we discuss the importance of the natural flow regime for functioning riverine ecosystems and provide examples from four tributaries to the Green River, a major headwater branch of the Colorado River. These tributaries represent a gradient of impacts ranging from water abstraction to the point of complete seasonal desiccation to a relatively natural flow regime, and consequently have maintained different levels of instream habitat complexity and native fish persistence. Despite decades of management, endangered species lack self‐sustaining populations and other native species have been extirpated from over half their ranges, which begs the question: can water development and fish conservation be balanced under current water laws and climate change‐driven declines in runoff? Given the continued decline in freshwater biodiversity and abundance occurring across the globe, we contend that immediate designation of rivers with natural flow regimes as freshwater conservation areas will enhance native species recovery.

From pastures to forests: Changes in Mediterranean wild bee communities after rural land abandonment

Abstract In farmland landscapes worldwide, there are pervasive trends for either intensification or abandonment. Intensification is a widely recognised driver of wild bee declines, but little is known about the consequences of land abandonment, though it involves major habitat shifts from fallows, pastures and meadows, to shrublands and forests. Focusing on a Mediterranean landscape, we investigated long‐term changes in wild bee communities during secondary vegetation succession after land abandonment. We used a space‐for‐time substitution approach, sampling plants and wild bees on five successional stages, from grasslands, through shrublands, to oak woodlands. We recorded 2721 bees, representing over 150 species. Grasslands had the highest wild bee abundance and high diversity of oligolectic species. Moving through successional stages, there was a rapid decline in bee abundance combined with a progressive accumulation of rare species, resulting in maximum diversity of the overall community, ground nesters, polyleges, and oligoleges in oak woodlands. Bee diversity was positively related to plant taxonomic and phylogenetic diversity. There was high turnover in community composition along the succession, with species occurring in grasslands being largely absent from later successional stages, and vice versa. From 21 indicator species, 17 were associated with grasslands, including the only threatened species. Our results suggest that a mosaic of habitats at different successional stages, particularly grasslands and oak woodlands, are necessary to maximise the diversity and abundance of wild bees at the landscape scale. Sustained management is thus needed under land abandonment to retain early‐successional herbaceous habitats and to ensure woodland regeneration and protection.

The Rapid Population Collapse of a Key Marine Predator in the Northern Antarctic Peninsula Endangers Genetic Diversity and Resilience to Climate Change

Antarctic fur seals (AFS) are an ecologically important predator and a focal indicator species for ecosystem-based Antarctic fisheries management. This species suffered intensive anthropogenic exploitation until the early 1900s, but recolonized most of its former distribution, including the southern-most colony at Cape Shirreff, South Shetland Islands (SSI). The IUCN describes a single, global AFS population of least concern; however, extensive genetic analyses clearly identify four distinct breeding stocks, including one in the SSI. To update the population status of SSI AFS, we analyzed 20 years of field-based data including population counts, body size and condition, natality, recruitment, foraging behaviors, return rates, and pup mortality at the largest SSI colony. Our findings show a precipitous decline in AFS abundance (86% decrease since 2007), likely driven by leopard seal predation (increasing since 2001, p << 0.001) and potentially worsening summer foraging conditions. We estimated that leopard seals consumed an average of 69.3% (range: 50.3–80.9%) of all AFS pups born each year since 2010. AFS foraging-trip durations, an index of their foraging habitat quality, were consistent with decreasing krill and fish availability. Significant improvement in the age-specific over-winter body condition of AFS indicates that observed population declines are driven by processes local to the northern Antarctic Peninsula. The loss of SSI AFS would substantially reduce the genetic diversity of the species, and decrease its resilience to climate change. There is an urgent need to reevaluate the conservation status of Antarctic fur seals, particularly for the rapidly declining SSI population.

Towards recycling remediated cyanidation tailings water to the mineral biooxidation process – Impact on microbial community and its performance

Biooxidation is a well-established pretreatment technology used in refractory gold mineral processing to enhance metal value recovery. The technology is microbially-mediated and is dependent on appropriate quality water for optimum function. The influence of remediated cyanidation tailings effluent and increasing thiocyanate (SCN−) concentration on a biooxidation microbial community was evaluated in small-scale batch tests. Changes in ferrous iron (Fe2+) oxidation activity, microbial growth and microbial community structure were evaluated. Two detoxified tailings wastewater samples, one sourced from an industrial operation and another from a laboratory system, were evaluated and used as the liquid matrix for medium preparation. These were compared with a standard laboratory medium described for the cultivation of acidophilic biooxidation organisms. Additionally, the effect of increasing SCN− concentration over the range of 0–5 mg/L across the different nutrient matrices. Similar microbial growth and Fe2+ oxidation activity with a nominal shift in community structure were observed in nutrient media containing remediated tailings wastewater relative to experiments conducted using defined medium prepared with deionised water (dH2O). However, a lag in the onset of Fe2+ oxidation activity was observed in systems cultured in media containing remediated effluent. This was attributed to the coupled presence of anions, NO3– and SCN−, in conjunction with additional constituents within the remediated effluent matrix. Exposure to SCN− concentrations up to 1 mg/L across all nutrient media demonstrated marginal differences in Fe2+ oxidation performance, although the observed lag in Fe2+ oxidation activity was sustained in remediated effluent tests. At a SCN– concentration of 1.4 mg/L Fe2+ oxidation activity within the defined medium system was inhibited, however systems cultivated in remediated tailings water exhibited sustained Fe2+ oxidation performance at 1.4 mg SCN− mg/L. Exposure to SCN− concentrations above 1.4 mg/L resulted in negligible Fe2+ oxidation activity, lower cell concentrations and a significant increase in growth lag time in detoxified tailings water media. Microbial community structure data illustrated that Leptospirillum ferriphilum was the dominant Fe2+ oxidising species within all systems; and its decline in abundance at elevated SCN− concentrations corresponded to poor Fe2+ utilisation. The abundance (and inferred growth rate) of sulfur-oxidising Acidithiobacillus caldus remained constant across the SCN− range explored. Abundance of Acidiplasma cupricumulans was found to increase at SCN− concentrations above 1 mg/L; however, it did not contribute toward Fe2+ oxidation. Results from this study indicated that inclusion of remediated tailings wastewater within the biooxidation circuit would be feasible causing negligible disruption to process performance; however, SCN− concentrations should not exceed 1 mg/L.

A decrease in the number and the timing shift of the bird arrival in the North-Eastern Baikal Region

The article deals with the main results of a long-term study of birds in the Barguzin State Nature Biosphere Reserve (Russia). Phenological observations of the bird spring arrival have been carried out from 1938 to 2020. Monitoring of bird communities has been carried out from 1984 to 2020 on permanent counting routes in the valleys of three rivers in the area from the Lake Baikal coast to the highlands of the Barguzin Range (460–1700 m a.s.l.). We detected shifts and cyclical changes in the timing of the bird arrival and revealed a steady decrease in the abundance of the bird population after 1997–1998. The long-term series of observations (taking into account of model bird groups) made it possible to identify some responses of the biota to climatic changes in the Lake Baikal Region. Twenty-six species (40.0%) began to arrive in spring statistically significantly earlier, seven species (10.8%) significantly later, and for 32 species (49.2%) the arrival timing did not change statistically significantly. In contrary to Europe and North America, in the Baikal Region, the proportion of distant migrants in the group of early arriving bird species is higher than in the group of nearby migrants. We suggest that these differences may be associated with different wintering areas of long-distance migrants (species of the Baikal Region winter in South and Southeast Asia in contrast to African wintering areas of European birds). In the Baikal Region, the periods of high and low abundance in background species populations are probably associated with the passage of wet and dry phases of a long climatic cycle. We have identified positive trends in long-term changes in abundance for seven background species (14.0%), and a steady decline in abundance for 17 species (34.0%). In addition, we noted an equal ratio of species with a positive and negative trend in native species abundance. Negative trends of changes in the number of distant and nearby migrants prevailed over positive (increase) trends. So, we found 14 species with negative and four species with positive trends. An increase in the duration of observations makes it possible to give a more reliable assessment of processes in population dynamics, and identify mechanisms of the influence of meteorological and phenological factors on the dynamics of the abundance of bird species. This makes it possible to predict some biota responses to long-term climate changes in the absence of anthropogenic transformations of the natural environment.

Effects of aerial adulticiding for mosquito management on nontarget insects: A Bayesian and community ecology approach

AbstractDiseases transmitted by mosquitoes are emerging across the globe in a broad range of urbanized, rural, and natural environments inhabited by their vector species. Because applications of insecticides remain the most effective, and often the only available tool to prevent or control mosquito‐borne disease outbreaks, their use and scope continue to expand. However, the effects of multiple insecticide applications targeting adult mosquitoes on nontarget insect communities remain poorly characterized. To remedy this knowledge gap, we conducted an evaluation of five aerial insecticide applications on insect communities in a natural environment near Salt Lake City, Utah. Employing a before–after–control–impact approach, we assessed abundance and community composition changes over the study period utilizing Bayesian and community ecology analytical methods. We observed no discernible effects on most insect taxa, and there were no changes in the overall insect community composition. The abundance of Diptera, Coleoptera, and Hemiptera declined in control and treatment sites, Odonata increased over the period of the study, and Hymenoptera and Lepidoptera remained similar, suggesting seasonal trends rather than treatment effects. The only consistently detectable treatment effect was on nonbiting midges (Diptera: Chironomidae), that are closely related to mosquitoes taxonomically and have similar body size and diel activity. Midge abundance declined by 79.9% (95% credible interval: 58.4–91.9). Overall posttreatment abundance decline of 62.2% (95% credible interval: 22.5–87.8) was also detected for leafhoppers (Hemiptera: Cicadellidae), but, these declines were inconsistent and may be attributed to natural variability rather than the treatment effect. Treatment frequency, location, life‐stage targeting, and application techniques may mitigate the effects of mosquito control on nontarget insects to allow protecting human health while limiting environmental impacts.

Toward a conceptual framework for managing and conserving marine habitats: A case study of kelp forests in the Salish Sea.

Kelp forests are in decline across much of their range due to place‐specific combinations of local and global stressors. Declines in kelp abundance can lead to cascading losses of biodiversity and productivity with far‐reaching ecological and socioeconomic consequences. The Salish Sea is a hotspot of kelp diversity where many species of kelp provide critical habitat and food for commercially, ecologically, and culturally important fish and invertebrate species. However, like other regions, kelp forests in much of the Salish Sea are in rapid decline. Data gaps and limited long‐term monitoring have hampered attempts to identify and manage for specific drivers of decline, despite the documented urgency to protect these important habitats. To address these knowledge gaps, we gathered a focus group of experts on kelp in the Salish Sea to identify perceived direct and indirect stressors facing kelp forests. We then conducted a comprehensive literature review of peer‐reviewed studies from the Salish Sea and temperate coastal ecosystems worldwide to assess the level of support for the pathways identified by the experts, and we identified knowledge gaps to prioritize future research. Our results revealed major research gaps within the Salish Sea and highlighted the potential to use expert knowledge for making informed decisions in the region. We found high support for the pathways in the global literature, with variable consensus on the relationship between stressors and responses across studies, confirming the influence of local ecological, oceanographic, and anthropogenic contexts and threshold effects on stressor–response relationships. Finally, we prioritized areas for future research in the Salish Sea. This study demonstrates the value expert opinion has to inform management decisions. These methods are readily adaptable to other ecosystem management contexts, and the results of this case study can be immediately applied to kelp management.

Effects of submerged aquatic vegetation and water quality on waterfowl abundance by foraging guild

Abstract Back Bay, Virginia, has been documented as an important foraging area for waterfowl since at least the mid‐1800s. Expansive submerged plant beds historically supported diverse assemblages of non‐breeding waterfowl; however, coastal development and other anthropogenic influences have since led to fluctuations in submerged aquatic vegetation (SAV) and an associated decline in waterfowl abundance in the bay. To gain insight into the effects of environmental drivers on waterfowl foraging guilds, our study explores the effects of SAV frequency and water quality on the abundance of dabbling ducks, diving ducks and swans and geese in Back Bay. We use 8 years of SAV, water quality, and waterfowl monitoring data collected by state and federal agencies to model the effects of salinity, turbidity, pH and percent frequency of SAV on the relative abundance of waterfowl by foraging guild in Back Bay. The appropriateness of the data and reasonability of the preliminary results were then evaluated through semi‐structured interviews with 11 local informants representing state, federal and non‐governmental organizations. Quantitative results indicated that dabbling ducks are affected differently than other guilds by water quality and percent frequency of SAV. Thematic analysis of the interview data revealed a number of potential explanations for the model results, as well as highlighted areas of uncertainty in need of further research. In a test of face validity, participants demonstrated a significant degree of belief in turbidity, salinity and SAV as drivers of waterfowl abundance, but were not convinced by the potential effects of pH as demonstrated by the model. This mixed methods study provides insights that could potentially influence the management and conservation of non‐breeding waterfowl populations by challenging the assumption that particular environmental conditions serve all foraging groups equally.

The island hoppers: how foraging influences green turtle Chelonia mydas abundance over space and time in the Lakshadweep Archipelago, India

Adult green turtles are known to display either preference in their foraging habits or fidelity to their foraging sites which, in turn, influences their migrations and the availability of forage. With an abundant supply of seagrass and algae, the lagoons of the Lakshadweep Archipelago off the Indian west coast serve as significant feeding grounds for green turtles. In the last 2 decades, the numbers of foraging green turtles have varied across islands, leading to speculation about their foraging patterns and movements. We collated secondary data and conducted periodic surveys between 2013 and 2019 to record trends in green turtle abundance and seagrass characteristics and investigate relationships between them. Over the last decade, green turtle abundances have fluctuated widely with increases followed by sharp declines within different lagoons. Our results also show that a reduction in seagrass density, particularly Thalassia sp. and Cymodocea sp., coincided with the decline in green turtle abundance. Moreover, turtle presence was observed at sites with higher seagrass density and canopy height. Our findings indicate that green turtles appeared to forage in particular lagoons until their preferred resources declined, before moving to other islands within the Archipelago or other unknown locations. Therefore, to devise effective management strategies, it is crucial to understand how this green turtle population will adapt to the decline in foraging resources. The declining seagrass populations also suggest the need for an ecosystem approach towards green turtle conservation.