Fin whales of the Great Bear Rainforest: Balaenoptera physalus velifera in a Canadian Pacific fjord system

Fin whales (Balaenoptera physalus) are widely considered an offshore and oceanic species, but certain populations also use coastal areas and semi-enclosed seas. Based upon fifteen years of study, we report that Canadian Pacific fin whales (B. p. velifera) have returned to the Kitimat Fjord System (KFS) in the Great Bear Rainforest, and have established a seasonally resident population in its intracoastal waters. This is the only fjord system along this coast or elsewhere in which fin whales are known to occur regularly with strong site fidelity. The KFS was also the only Canadian Pacific fjord system in which fin whales were commonly found and killed during commercial whaling, pointing to its long-term importance. Traditional knowledge, whaling records, and citizen science databases suggest that fin whales were extirpated from this area prior to their return in 2005–2006. Visual surveys and mark-recapture analysis documented their repopulation of the area, with 100–120 whales using the fjord system in recent years, as well as the establishment of a seasonally resident population with annual return rates higher than 70%. Line transect surveys identified the central and outer channels of the KFS as the primary fin whale habitat, with the greatest densities occurring in Squally Channel and Caamaño Sound. Fin whales were observed in the KFS in most months of the year. Vessel- and shore-based surveys (27,311 km and 6,572 hours of effort, respectively) indicated regular fin whale presence (2,542 detections), including mother-calf pairs, from June to October and peak abundance in late August–early September. Seasonal patterns were variable year-to-year, and several lines of evidence indicated that fin whales arrived and departed from the KFS repeatedly throughout the summer and fall. Additionally, we report on the population’s social network and morphometrics. These findings offer insights into the dynamics of population recovery in an area where several marine shipping projects are proposed. The fin whales of the Great Bear Rainforest represent a rare exception to general patterns in this species’ natural history, and we highlight the importance of their conservation.

Urban organic aerosol composition in eastern China differs from north to south: molecular insight from a liquid chromatography–mass spectrometry (Orbitrap) study

Air pollution by particulate matter in China affects human health, the ecosystem and the climate. However, the chemical composition of particulate aerosol, especially of the organic fraction, is still not well understood. In this study, particulate aerosol samples with a diameter of ≤2.5 µm (PM2.5) were collected in January 2014 in three cities located in northeast, east and southeast China, namely Changchun, Shanghai and Guangzhou. Organic aerosol (OA) in the PM2.5 samples was analyzed by an ultrahigh-performance liquid chromatograph (UHPLC) coupled to a high-resolution Orbitrap mass spectrometer in both negative mode (ESI-) and positive mode electrospray ionization (ESI+). After non-target screening including the assignment of molecular formulas, the compounds were classified into five groups based on their elemental composition, i.e., CHO, CHON, CHN, CHOS and CHONS. The CHO, CHON and CHN groups present the dominant signal abundances of 81 %–99.7 % in the mass spectra and the majority of these compounds were assigned to mono- and polyaromatics, suggesting that anthropogenic emissions are a major source of urban OA in all three cities. However, the chemical characteristics of these compounds varied between the different cities. The degree of aromaticity and the number of polyaromatic compounds were substantially higher in samples from Changchun, which could be attributed to the large emissions from residential heating (i.e., coal combustion) during wintertime in northeast China. Moreover, the ESI- analysis showed higher H/C and O/C ratios for organic compounds in Shanghai and Guangzhou compared to samples from Changchun, indicating that OA undergoes more intense photochemical oxidation processes in lower-latitude regions of China and/or is affected to a larger degree by biogenic sources. The majority of sulfur-containing compounds (CHOS and CHONS) in all cities were assigned to aliphatic compounds with low degrees of unsaturation and aromaticity. Here again, samples from Shanghai and Guangzhou show a greater chemical similarity but differ largely from those from Changchun. It should be noted that the conclusions drawn in this study are mainly based on comparison of molecular formulas weighted by peak abundance and thus are associated with inherent uncertainties due to different ionization efficiencies for different organic species.

Abundance and Seasonality of Phytoplankton, Zooplankton and Anuran Species in Selected Wetlands of Kogi State, Nigeria

Phytoplankton, Zooplankton and anurans play vital role in the working of wetland ecosystems as they form its dynamic food web. This study was designed to determine the abundance and seasonality of Phytoplankton, Zooplankton and Anuran species in selected wetlands of Kogi State, Nigeria. The study was performed in Abu’ja wetland in Dekina Local Government area and Egwubi seasonal wetland in Ejule, Ofu Local Government area of Kogi state. From each sampled wetlands planktons were collected with plankton net at the sites. Overall, 854 specimens of anurans, 584 from Abu’ja and 270 from Egwubi sites were collected within a period of eighteen months. The abundance of phytoplankton, zooplankton and anuran species were computed. Abundance was computed as a proportion of numbers of organisms in a group to the summation of the total number in all the groups being considered. Simpson’s index (Dominance), Gini-Simpson's, Shannon-Wiener index, Berger-Parker index, Margalef’s index, Menhinick’s index, Fisher alpha, Equitability index, Brillouin index and Chao index were all calculated following standard methods. The data collected was analyzed using the Statistical Package for Social Sciences (SPSS) version 20.0, PAST version 3.14 and Microsoft Office. Level of significance was p < 0.05. Anuran species found in both wetlands included Amietophrymus regularis, A. maculatus and Hoplobatracchus occipitalis. Phytoplankton species encountered in both study stations include Oscilatoria spp, Anabaenia spp, Anacystis spp, Spirogyra spp, Oedogonium spp, Savicular spp and Euglena spp. Zooplanktons encountered include Epiphanes spp, Philodina spp, Synchata spp, Poliathra spp, Holopedium spp, Daphnia spp, Alona spp and Bosmina spp. The abundance and seasonality of phytoplankton, zooplankton and anurans in the selected wetlands studied in Kogi state, Nigeria showed that the organisms abundance are highly influenced by the seasons in Kogi State, with its peak abundance in rainy season and very low abundance in dry season.

Seasonality and timing of peak abundance of Aedes albopictus in Europe: Implications to public and animal health

Aedes albopictus is a known vector of dengue and chikungunya. Understanding the population dynamics characteristics of vector species is of pivotal importance to optimise surveillance and control activities, to estimate risk for pathogen-transmission, and thus to enhance support of public health decisions. In this paper we used a seasonal activity model to simulate the start (spring hatching) and end (autumn diapause) of the vector season. In parallel, the peak abundance of the species was assessed using both VectorNet field survey data complemented with field studies obtained from literature across the Mediterranean Basin. Our results suggest that spring hatching of eggs in the current distribution area can start at the beginning of March in southern Europe and in April in western Europe. In northern Europe, where the species is not (yet) present, spring hatching would occur from late April to late May. Aedes albopictus can remain active up to 41 weeks in southern Europe whilst the climatic conditions in northern Europe are limiting its potential activity to a maximum of 23 weeks. The peak of egg density is found during summer months from end of July until end of September. During these two months the climatic conditions for species development are optimal, which implies a higher risk for arbovirus transmission by Ae. albopictus and occurrence of epidemics.

Short-term variation in abundance of four Acartia species (Copepoda, Calanoida) in a eutrophic bay

The short-term variation in the abundance of Acartia copepods in the eutrophic Gamak Bay of South Korea was investigated with weekly measurements from October 2007 to September 2008. During this period, four Acartia species (A. erythraea, A. ohtsukai, A. omorii, and A. sinjiensis) were recorded as showing seasonally different peak abundance. The abundance of A. erythraea and A. sinjiensis was high in autumn, whereas that of A. omorii was high from winter to spring. In summer, A. erythraea, A. ohtsukai, and A. sinjiensis coexisted at peak abundance significantly related to water temperature and salinity. Results from the response curves of the four Acartia species to water temperature and salinity suggest that A. erythraea and A. sinjiensis increased in abundance at water temperatures >18 °C, whereas A. ohtsukai increased in abundance at water temperatures >27 °C. The occurrence of A. erythraea, A. ohtsukai, and A. sinjiensis decreased with increasing salinity, but chlorophyll-a concentration showed no effect on occurrence. Despite these findings, the coexistence of the three ecologically similar species may be due to prey abundance in summer and autumn (chlorophyll-a concentration >10 µg L−1). Notably, the wide range of the response curve of A. omorii indicates its occurrence at higher salinity levels than other species.

Occurrence and Pest Severity of Whitefly on Different Varieties of Chili

Seasonal abundance, distribution and pest severity of white fly, Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) were studied on the chili (Capsicum spp.) varieties namely BARI Morich 1, BARI Morich 2, BARI Morich 3, BINA Morich 1 and Bogura Morich during November 2017 to June 2018 at Gazipur in Bangladesh. Results showed that the white fly started to build up their population from 2nd week of February on the chili varieties and exerted the peak abundance at the last week of February when the plants were at flowering stage. Abundances of white fly positively correlated with maximum temperature and relative humidity, and negatively correlated with minimum temperature and rainfall. Meteorological parameters predicted 11.6 to 32.9% abundance of whitefly on the chili varieties. Occurrence of white fly on different strata of the varieties was statistically low on BARI Morich 2 compared to other varieties. Virus infection levels among the varieties differed significantly and BARI Morich 2 showed the lowest level of infection. BARI Morich 2, Bogura Morich and BARI Morich 1 revealed low level of leaf curl indices (6.8 to 9.3%) and these varieties could be selected for cultivation in the areas where whitefly is a major pest of chili. Ann. Bangladesh Agric. (2020) 24(1) : 127-135

EFFECT OF POULTRY LITTER AS AN ORGANIC FERTILIZER, IN WATER QUALITY, PARASITIC ABUNDANCE, AND GROWTH NILE TILAPIA

Nile tilapia feed on plankton in natural environments. This food source can be increased in ponds through fertilization and can reduce feed expenses or improve fish performance when used as supplementary food. Organic fertilization is an alternative to commercial fertilization; however, its use increases concerns regarding water quality and sanitary aspects. This study aimed to evaluate the effects of the use of poultry litter as organic fertilizer on the physical and chemical parameters of water, gill ectoparasite metazoan abundance, and growth of Nile tilapia (Oreochromis niloticus) during the culture cycle lasting 240 days. Four earthen ponds, two fertilized with poultry litter and two non-fertilized ponds, as fertilized and non-fertilized treatments, respectively, were used. Stocking density was 3 fish per m2 with an average initial weight of 0.64 ± 0.15 g. The mean water quality values and the growth performance parameters of Nile tilapia did not show significant differences between the two treatments. The gill parasites found in the fish belonged to the class Monogenea, comprising two genera, Cichlidogyrus and Scutogyrus, with significant differences between treatments. The non-fertilized treatment showed a high abundance of parasites throughout the culture cycle months, with peak abundance in the months with low concentrations of dissolved oxygen in the water.

Sharing the burden? Earthworms and woodlice show seasonal complementarity in peak abundances in soil in an oak-beech temperate woodland

Complementarity between functional analogues can confer resistance and resilience on ecosystems in the face of environmental change. High biodiversity can lead to increased ecosystem functionality through complementary effects. Earthworms, woodlice and millipedes can have high densities in leaf litter and soils, but little is known about their seasonal patterns. The two groups play important roles in the breakdown and incorporation of organic matter into soils. Differences in peak abundance could affect the rates of litter break down and incorporation in different seasons. We sampled earthworms, woodlice and millipedes from leaf litter soil every month for ten years in a New Forest woodland. We used non-parametric regression to explore monthly and yearly variation in the abundance of decomposer organisms and soil temperature and moisture. Earthworms have a distinct seasonal peak in density different from woodlice and millipedes. Earthworm peak density is in the winter and spring and is correlated with greatest soil moisture. Woodlice (and millipede) have their peak density is in the summer and is correlated with the highest soil temperatures. This means that earthworms, woodlice and millipedes have complementary peaks in abundance. These two groups have similar functional roles in litter decomposition and these data imply ecological complementarity in this important ecological process. This effect is likely to be widespread in lowland woodland in the UK and Europe, with only extreme temperatures and low pH limiting the distribution. Increased summer drought as a result of climate change may lead to changes in the relative abundance of these three groups and in particular local extinctions of earthworms which will in turn affect litter decomposition.

Abundance and Diversity of Dung Beetles (Coleoptera: Scarabaeoidea) as Affected by Grazing Management in the Nebraska Sandhills Ecosystem

Dung beetles (Coleoptera: Scarabaeoidea) serve a significant role in regulating ecosystem services on rangelands. However, the influence of grazing management on dung beetle communities remains largely unknown. The purpose of this study was to investigate dung beetle abundance and diversity throughout the grazing season in the Nebraska Sandhills Ecoregion. Grazing treatments included: continuous grazing (CONT), low-stocking rotational grazing (LSR), high-stocking rotational grazing (HSR), and no grazing (NG). The abundance and diversity of dung beetles were measured in the 2014 and 2015 grazing seasons using dung-baited pitfall traps. Dung beetle abundance for each grazing treatment was characterized through four indices: peak abundance, species richness, Simpson’s diversity index, and Simpson’s evenness. A total of 4,192 dung beetles were collected through both years of trapping in this study. Peak abundance and species richness were greater in grazed treatments when compared to NG in both years. Peak abundance in the HSR was 200% (2014) and 120% (2015) higher than in the LSR. Species richness in the HSR was 70% (2014) and 61% (2015) higher than in the LSR, and 89% (2014) and 133% (2015) higher than in CONT. Simpson’s diversity index was lower in the NG and CONT treatments when compared to the LSR or HSR treatments for both years. We conclude that rotational grazing, regardless of stocking density, promoted dung beetle abundance and diversity within the Nebraska Sandhills Ecoregion.