Mixoplankton interferences in dilution grazing experiments

It remains unclear as to how mixoplankton (coupled phototrophy and phagotrophy in one cell) affects the estimation of grazing rates obtained from the widely used dilution grazing technique. To address this issue, we prepared laboratory-controlled dilution experiments with known mixtures of phyto-, protozoo-, and mixoplankton, operated under different light regimes and species combinations. Our results evidenced that chlorophyll is an inadequate proxy for phytoplankton when mixoplankton are present. Conversely, species-specific cellular counts could assist (although not fully solve) in the integration of mixoplanktonic activity in a dilution experiment. Moreover, cell counts can expose prey selectivity patterns and intraguild interactions among grazers. Our results also demonstrated that whole community approaches mimic reality better than single-species laboratory experiments. We also confirmed that light is required for protozoo- and mixoplankton to correctly express their feeding activity, and that overall diurnal grazing is higher than nocturnal. Thus, we recommend that a detailed examination of initial and final plankton communities should become routine in dilution experiments, and that incubations should preferably be started at the beginning of both day and night periods. Finally, we hypothesize that in silico approaches may help disentangle the contribution of mixoplankton to the community grazing of a given system.

Constraints as Perceived and Suggestions as Expressed by Sheep Rearing Farmers in Raichur District of Karnataka, India

The study was conducted in purposively selected Raichur district of Karnataka. Highest number of sheep population criteria were used in selection of taluks and villages. A total of 120 respondents were selected from 06 selected villages of 2 taluks namely Lingasuguru and Raichur The quantitative and qualitative data were used to collected the information through interview schedule, The present study is highlighted different constraints and suggestion perceived by sheep rearing farmers during management practices simple statistical tools frequency and percentage are used in the study. In socio economic constraints the result found that majority (71.67%) poor knowledge and Ignorance on management practices followed literacy rate (62.05 %), It was found that a high majority (92.50%) unaware insurance services, poor credit facilities (87.50%), shrinkage of grazing land (76.67%) and cost of medicine (61.67%). Suggestion expressed by 69.17 per cent suggested on vaccination followed by keeping quality of buck (65.00%), increase number of veterinary hospital and staff (60.00%) and increase the community grazing land (37.50%), more than three-fourth of sheep farmers suggested discourage the middle man in market, strengthening the existing the animal market (72.50%) and develop new marketing channel (63.33%).

Land use influence on distribution and abundance of herbivores in Samburu-Laikipia, Kenya

The distribution and abundance of different wildlife herbivores was studied in Samburu-Laikipia landscape. The study sites included; Mpala and Oljogi, both commercial ranches in Laikipia district; Oldonyiro and Kipsing community areas in Isiolo district; West Gate Conservancy, Ngaroni Community area, Kalama Community area and Sessia-Barsalinga Community area in Samburu district; and Buffalo Spring National Reserve and Samburu National Reserve both protected areas in the landscape. The objectives of the study were: 1) Determine the influence of different land use on seasonal abundances and distribution wildlife species and 2) Examine the influence of livestock, human settlements and water on wildlife species in Samburu-Laikipia landscape. Distance sampling was used to estimate wildlife, livestock and bomas densities. Distance to nearest water was projected from GPS coordinates for both wildlife and livestock sighting using ARCGIS. Our analysis showed non-uniform distributions of wildlife groups across the Samburu-Laikipia ecosystem largely driven by seasonal rainfall patterns and land use types. Like predicted, most wildlife groups occurred in higher abundances on protected areas, Laikipia commercial ranches and community conservancies unlike in community grazing areas in both dry and wet season. However, large grazers increased substantially in community grazing areas over the wet season when livestock grazing was heavy, stimulating growth of short annuals plants of high-quality nutrients. Human activities had negative influences on all wildlife groups. Our findings indicate that the type of land -use influenced herbivore distribution and abundance in Samburu-Laikipia landscape. This suggests that human activities, including pastoralism, in conjunction with season rainfall patterns and land-use shape herbivore distribution and abundance in the area. Conservation strategies for successfully increasing survival of wildlife therefore, requires maintenance of a mixture of land-use types with well controlled and sustainable development.

TÁC ĐỘNG CỦA VIỆC THU HỒI ĐẤT ĐỂ XÂY DỰNG NHÀ MÁY ĐIỆN MẶT TRỜI ĐẾN CHĂN THẢ GIA SÚC CỦA CỘNG ĐỒNG ĐỊA PHƯƠNG Ở XÃ CHƯ GU, HUYỆN KRÔNG PA, TỈNH GIA LAI

Nghiên cứu tác động của việc thu hồi đất để xây dựng nhà máy điện mặt trời đến chăn thả gia súc của cộng đồng đã được tiến hành tại xã Chư Gu, huyện Krông Pa, tỉnh Gia Lai năm 2018. Phương pháp nghiên cứu đánh giá nông thôn có sự tham gia đã được sử dụng tại 4 thôn, buôn bị ảnh hưởng bởi nhà máy. Kết quả nghiên cứu cho thấy bò, dê là tài sản quí, được sử dụng trong các nghi lễ quan trọng của người dân tộc Jrai. Việc chuyển nhượng 7,2 ha đất để xây dựng nhà máy điện mặt trời đã tác động trực tiếp đến chăn thả gia súc, giảm lượng thức ăn tính theo vật chất khô 49,26 tấn/năm, làm giảm tiếp cận đến khu vực chăn thả phía sau, tăng lượng thức ăn thêm tại chuồng (rơm: 1,2 lần, cỏ trồng: 1,36 lần, cỏ cắt: 1,26 lần) so với năm 2017. Dự án đã làm mâu thuẫn liên quan đến chăn thả bò gia tăng, người dân không còn kết hợp được việc chăn thả và lấy củi, tai nạn đuối nước xảy ra nhiều hơn vào mùa mưa và tai nạn giao thông có xu thế gia tăng trên Quốc lộ 25. Khi nhà máy điện đi vào hoạt động, số lượng gia súc của 4 thôn, buôn giảm đáng kể, trong đó bò giảm 9,32% và dê giảm tới 42,13% so với đàn gia súc năm 2016. ABSTRACT The research on the impact of land acquisition to build Solar Power Station on community grazing lands was conducted in Chu Gu Commune, Krong Pa District, Gia Lai Province in 2018. The survey was carried out by using the participatory rural appraisal in 4 hamlets under the project area. The result indicated that cattle, goats are valuable assets, used in important festivals of the Jrai people. The land acquisition of 7.2 ha to build the Solar Power Station has a direct impact on grazing capacity, including reducing feed input of 49.26 tones dry matter/year, reducing access to the hill behind, increasing the number of feed supplements at the barn (rice straw: 1.2 times, elephant grass: 1.36 times, natural grass cut: 1.26 times) compared to 2017. The project also increased conflicts related to grazing that local people can no longer combine with grazing and firewood collection, drowning accident happened more and more in the rainy season and traffic accidents tended to increase on Highway 25. When the project operated, the number of animals in 4 hamlets decreased remarkably, of which cattle decreased by 9.32% and goats decreased by 42.13% compared to 2016.

Site-Level Variation in Parrotfish Grazing and Bioerosion as a Function of Species-Specific Feeding Metrics

Parrotfish provide important ecological functions on coral reefs, including the provision of new settlement space through grazing and the generation of sediment through bioerosion of reef substrate. Estimating these functions at an ecosystem level depends on accurately quantifying the functional impact of individuals, yet parrotfish feeding metrics are only available for a limited range of sites, species and size classes. We quantified bite rates, proportion of bites leaving scars and scar sizes in situ for the dominant excavator (Cetoscarus ocellatus, Chlorurus strongylocephalus, Ch. sordidus) and scraper species (Scarus rubroviolaceus, S. frenatus, S. niger, S. tricolor, S. scaber, S. psittacus) in the central Indian Ocean. This includes the first record of scar frequencies and sizes for the latter three species. Bite rates varied with species and life phase and decreased with body size. The proportion of bites leaving scars and scar sizes differed among species and increased with body size. Species-level allometric relationships between body size and each of these feeding metrics were used to parameterize annual individual grazing and bioerosion rates which increase non-linearly with body size. Large individuals of C. ocellatus, Ch. strongylocephalus and S. rubroviolaceus can graze 200–400 m2 and erode >500 kg of reef substrate annually. Smaller species graze 1–100 m2 yr−1 and erode 0.2–30 kg yr−1. We used these individual functional rates to quantify community grazing and bioerosion levels at 15 sites across the Maldives and the Chagos Archipelago. Although parrotfish density was 2.6 times higher on Maldivian reefs, average grazing (3.9 ± 1.4 m2 m−2 reef yr−1) and bioerosion levels (3.1 ± 1.2 kg m−2 reef yr−1) were about 15% lower than in the Chagos Archipelago (4.5 ± 2.3 and 3.7 ± 3.0, respectively), due to the dominance of small species and individuals in the Maldives (90% <30 cm length). This demonstrates that large-bodied species and individuals contribute disproportionally to both grazing and bioerosion. Across all sites, grazing increased by 66 ± 5 m2 ha−1 and bioerosion by 109 ± 9 kg ha−1 for every kg increase in parrotfish biomass. However, for a given level of parrotfish biomass, grazing and bioerosion levels were higher on Maldivian reefs than in the Chagos Archipelago. This suggests that small-bodied fish assemblages can maintain ecosystem functions, but only if key species are present in sufficiently high numbers.

Geometric Analysis of Regime Shifts in Coral Reef Communities

Coral reefs are among the many communities believed to exhibit regime shifts between alternative stable states, single-species dominance, and coexistence. Proposed drivers of regime shifts include changes in grazing, spatial clustering, and ocean temperature. Here we distill the dynamic regimes of coral-macroalgal interaction into a three-dimensional geometry, akin to thermodynamic phase diagrams of state transitions, to facilitate analysis. Specific regime-shifting forces can be understood as bifurcation vectors through the cubic regime geometry. This geometric perspective allows us to understand multiple forces simultaneously in terms of the stability and persistence of interacting species. For example, in a coral-macroalgae community, grazing on macroalgae can lead to alternative stable states when there is no spatial clustering (e.g., high habitat connectivity). However, with spatial clustering, grazing can lead to coexistence because of elevated local intraspecific competition. The geometrical analysis of regime shifts is applicable to any two-species communities and can help conservation efforts navigate complexity and abrupt changes.