177 research outputs found
Tropical Transpacific Shore Fishes
Tropical transpacific fishes occur on both sides of the world's largest
deep-water barrier to the migration of marine shore organisms, the 4,000- to
7,000-km-wide Eastern Pacific Barrier (EPB). They include 64 epipelagic oceanic
species and 126 species of shore fishes known from both the tropical eastern
Pacific (TEP) and the central and West Pacific. The broad distributions of 19
of 39 circumglobal transpacific species of shore fishes offer no clues to the origin
of their TEP populations; TEP populations of another 19 with disjunct Pacific
distributions may represent isthmian relicts that originated from New World
populations separated by the closure of the Central American isthmus. Eighty
species of transpacific shore fishes likely migrated eastward to the TEP, and 22
species of shore fishes (12 of them isthmian relicts) and one oceanic species
likely migrated westward from the TEP. Transpacific species constitute ~12%
of the TEP's tropical shore fishes and 15-20% of shore fishes at islands on the
western edge of the EPB. Eastward migrants constitute ~7% of the TEP's
shore-fish fauna, and a similar proportion of TEP endemics may be derived
from recent eastward immigration. Representation of transpacific species in
different elements of the TEP fauna relates strongly to adult pelagic dispersal
ability-they constitute almost all the epipelagic oceanic species, ~25% of
the inshore pelagic species, but only 10% of the demersal shore fishes. Taxa
that have multiple pelagic life-history stages are best represented among the
transpacific species. Among demersal teleosts that have pelagic larvae, pelagic
spawners are better represented than demersal spawners among transpacific
species, perhaps because offshore larval development and longer pelagic larval
durations provide the former with greater dispersal capabilities. There are
strong phylogenetic effects on representation in the transpacific fauna: (1) elasmobranchs
are proportionally better represented than teleosts, even teleosts
with more pelagic life-history stages; (2) a pelagic juvenile stage with great dispersal
potential allows tetraodontiforms that produce demersal or pelagic eggs
to be well represented; and (3) various speciose central Pacific families with
"adequate" larval dispersal characteristics lack transpacific species. El Niiios
potentially enhance eastward migration by increasing eastward flow and halving
transit times across the EPB. However, that effect may be offset by low productivity
and high temperatures in those eastbound flows. There is little clear
evidence of strongly increased migration across the EPB during El Niiios, including
recent extreme events (1982-1983 and 1997-1998). During such events
shore fishes in the TEP experience range expansions and become locally abundant at marginal areas such as the Galapagos, changes that can be confused with
increased migration across the EPB. Although there is a strong bias toward
eastward migration among the transpacific shore fishes, there likely is much
more westward migration than previously realized: 20-25% of transpacific species
may have migrated in that direction. Stronger eastbound than westbound
currents can account for this bias. Westward migrants have better developed
pelagic dispersal characteristics than many eastward migrants, suggesting that
westward migration is more difficult. Many westward migrants associate with
flotsam and flotsam-mediated migration is more likely to be westward. All
westward migrants occur at Hawai'i, but only about one-fifth of them at the
Marquesas. This bias may be due to: Hawai'i being a larger target and in the
path of most of the flotsam dispersal from the TEP; an eastward current that
impinges on the Marquesas, reducing westward arrivals; and most propagules
dispersing toward the tropical Marquesas originating in the temperate eastern
Pacific. However, the Hawaiian Islands also are much better sampled than the
Marquesas. Although the TEP reef-fish fauna may be depauperate relative to
that of the Indo-Malayan "center of diversity," it is as rich as the faunas of islands
on the western side of the EPB. Hence a preponderance of eastward migration
does not represent a response to a richness gradient across that barrier.
There is little evidence that a paucity of ecological groups in the native TEP
fauna is primarily responsible for the structure of the eastward-migrant fauna.
Rather, eastward migrants may simply represent a cross section of those in the
donor fauna, tempered by phylogenetic variation in dispersal ability. Because
few central Pacific fishes can live only on live corals and coral reefs, the rarity of
such reefs in the TEP is unlikely to strongly limit eastward migration. Differences
between oceanic and adjacent continental reef-fish faunas in the West
Pacific indicate that each is strongly tied to its respective habitat. Hence, the
rarity in the TEP of the (overwhelmingly) most abundant habitat present in the
central Pacific-tropical oceanic reefs-may strongly limit migration in both
directions across the EPB: there is little suitable habitat for eastward migrants in
the TEP and few suitable species and tiny source populations for westward migrants.
The global effects that oceanic/continental habitat differences have on
reef-fish biogeography need further assessment. Genetic data on ~18% of the
transpacific species indicate: that conspecific populations of oceanic species
(especially) and shore fishes are genetically well connected across the EPB; that
circumtropical taxa in the TEP include isolated isthmian relicts and recent
eastward migrants; that all five TEP species of one circumtropical genus (Thalassoma)
were derived by several eastward invasions after the closure of the
Isthmus of Panama; that some isolated Hawaiian central Pacific populations
were established by postisthmian invasion from the TEP; and that Indo-central
Pacific species unsuspectedly can co-occur with their endemic sibling sisters
in the TEP. Genetic data support distributional data that indicate a strong
preponderance of eastward migration across the EPB but also more westward
migration than previously thought. Future genetic studies should resolve
a question that distributional data cannot: how many widespread presumed
eastward-migrant transpacific species actually originated by westward migration
from the TEP
Butterfly pea - a legume success story in cropping lands of central Queensland
The central Queensland region is a major producer of wheat, sorghum and beef. Changes in relative values of cereals and beef, together with a market demand to finish steers at a younger age, has induced farmers to invest more resources into their beef enterprises. Soil fertility decline is seen as a major constraint to cereal production and one that can be overcome by use of pasture phases in crop rotations. Within this environment, butterfly pea (Clitoria ternatea) has emerged as a well-adapted summer-growing legume for the heavy textured cropping soils of the region. It is being sown into existing or new permanent pastures and in pasture phases within cropping rotations to improve animal production and soil nitrogen status. Butterfly pea is relatively inexpensive to establish and can provide liveweight gain of between 0.75 and 1.3 kg/head/day. The combination of farmer, extension and research inputs has resulted in widespread adoption with > 12,000 ha being successfully established over the past 3 years
Challenges of on-farm research - insights from the Central Queensland farming systems experience
The “Sustainable Farming Systems for Central Queensland” project aims to develop profitable and sustainable farming systems in central Queensland and to have these systems widely adopted. Farmer-based groups are involved in on-farm research into system components at ten locations in central Queensland, with project staff facilitating and guiding this research and system development.
At the project’s inception, on-farm research was seen as a means of integrating Research, Development and Extension (R,D&E), resulting in research outcomes relevant to producers therefore improving the rate of adoption. Although the use of on-farm research has produced locally relevant system components that are being adopted, using this methodology has not been without its challenges. This paper describes the experiences of the authors in implementing on-farm research, detailing the challenges faced and methods used to deal with them
Assessing water quality for cropping management practices: A new approach for dissolved inorganic nitrogen discharged to the Great Barrier Reef
Applications of nitrogen (N) fertiliser to agricultural lands impact many marine and aquatic ecosystems, and improved N fertiliser management is needed to reduce these water quality impacts. Government policies need information on water quality and risk associated with improved practices to evaluate the benefits of their adoption. Policies protecting Great Barrier Reef (GBR) ecosystems are an example of this situation. We developed a simple metric for assessing the risk of N discharge from sugarcane cropping, the biggest contributor of dissolved inorganic N to the GBR. The metric, termed NiLRI, is the ratio of N fertiliser applied to crops and the cane yield achieved (i.e. kg N (t cane)−1). We defined seven classes of water quality risk using NiLRI values derived from first principles reasoning. NiLRI values calculated from (1) results of historical field experiments and (2) survey data on the management of 170,177 ha (or 53%) of commercial sugarcane cropping were compared to the classes. The NiLRI values in both the experiments and commercial crops fell into all seven classes, showing that the classes were both biophysically sensible (c.f. the experiments) and relevant to farmers’ experience. We then used machine learning to explore the association between crop management practices recorded in the surveys and associated NiLRI values. Practices that most influenced NiLRI values had little apparent direct impact on N management. They included improving fallow management and reducing tillage and compaction, practices that have been promoted for production rather than N discharge benefits. The study not only provides a metric for the change in N water quality risk resulting from adoption of improved practices, it also gives the first clear empirical evidence of the agronomic practices that could be promoted to reduce water quality risk while maintaining or improving yields of sugarcane crops grown in catchments adjacent to the GBR. Our approach has relevance to assessing the environmental risk of N fertiliser management in other countries and cropping systems
Short-term rotations using the forage legume Lablab have a place in Central Queensland farming systems
Soil nitrogen fertility decline is a problem for the farmers of Central Queensland (CQ). Nitrogen fertilisers are now widely used, but an erratic climate means that economic returns are not always achieved. Two farmer groups in CQ have ongoing experiments to make economic comparisons between a lablab/cereal rotation and conventional grain cropping regimes. At Fernlees, a sequence of lablab/sorghum/wheat is being compared with wheat/sorghum/chickpea on a low fertility open downs soil. At Theodore, an unfertilised lablab/sorghum rotation is being compared with continuous fertilised sorghum. Results after three seasons indicate that the nitrogen benefit to subsequent crops plus returns from a ley legume phase can offset the opportunity cost of not growing a grain crop on a low fertility soil
Experiences from using Action Learning Groups to develop Sustainable Farming Systems for Central Queensland
Farmer-based action learning groups have been used to conduct on-farm research in the “Sustainable Farming Systems for Central Queensland” project, with the aim of developing profitable and sustainable farming systems and having them adopted. Group facilitators and technical staff help guide the groups using the action learning process. This guidance, and the use of adult learning principles has ensured that groups remain focussed on achieving their goals and that profitable and sustainable farming systems are adopted. This paper details the experiences gained in facilitating action learning at key points in group development, including group formation, planning and implementing research and evaluation. Key factors needed for effectively using action learning to develop profitable and sustainable farming systems and improve adoption are identified and discusse
“ECT should never stop”: Exploring the experiences and recommendations of ECT clinical directors and anesthetists about ECT during the COVID-19 pandemic
Electroconvulsive therapy (ECT) is an effective treatment option for severe, treatment-resistant, and life-threating psychiatric illness. The COVID-19 pandemic has significantly disrupted ECT services. Services across North America, Europe, and Australia have reported decreased ECT delivery, and changes in the ways ECT is delivered. This study aimed to identify the impacts of COVID-19 on ECT services globally by exploring clinicians' experiences about ECT during the pandemic, and their recommendations for reducing the negative impacts of the pandemic. Data were collected using an electronic, cross-sectional survey, which included elicitation of free-text responses. The survey was open from March to November 2021. Clinical directors in ECT services, their delegates, and anesthetists were invited to participate. This paper reports the qualitative analysis of responses provided. Fifty-two participants provided qualitative response/s; 74.5% were clinical directors or their delegates, and 25.5% were anesthetists. Greater than one-third of participants were from Australia/New Zealand, and there was also representation from North America, Europe, and the UK. Participants' responses were detailed, averaging 43 words. Three themes were identified: (1) Service provision, about the importance of ECT services continuing during the pandemic, (2) Preparedness, through guidelines and environmental design, and (3) Personal protection, about strategies to increase staff safety. This is the first multi-site, international study to document the experiences and recommendations of ECT clinical directors and anesthetists about the effect of COVID-19 on ECT practice. The findings inform evidence-based practice, and ensure people with major psychiatric illnesses continue to receive ECT during the pandemic
Strategies from A Multi-National Sample of Electroconvulsive Therapy (ECT) Services: Managing Anesthesia for ECT during the COVID-19 Pandemic
Electroconvulsive therapy (ECT) is important in the management of severe, treatment-resistant, and life-threatening psychiatric illness. Anesthesia supports the clinical efficacy and tolerability of ECT. The COVID-19 pandemic has significantly disrupted ECT services, including anesthesia. This study documents strategies for managing ECT anesthesia during the pandemic. Data were collected between March and November 2021, using a mixed-methods, cross-sectional, electronic survey. Clinical directors in ECT services, their delegates, and anesthetists worldwide participated. One hundred and twelve participants provided quantitative responses to the survey. Of these, 23.4% were anesthetists, and the remainder were ECT clinical directors. Most participants were from Australia, New Zealand, North America, and Europe. Most were located in a public hospital, in a metropolitan region, and in a ‘medium/high-risk’ COVID-19 hotspot. Half of the participants reported their services made changes to ECT anesthetic technique during the pandemic. Services introduced strategies associated with anesthetic induction, ventilation, use of laryngeal mask airways, staffing, medications, plastic barriers to separate staff from patients, and the location of extubation and recovery. This is the first multi-national, mixed-methods study to investigate ECT anesthesia practices during the COVID-19 pandemic. The results are vital to inform practice during the next waves of COVID-19 infection, ensuring patients continue to receive ECT
Liveweight prediction from hip height, condition score, fetal age and breed in tropical female cattle
Hip height, body condition, subcutaneous fat, eye muscle area, percentage Bos taurus, fetal age and diet digestibility data were collected at 17 372 assessments on 2181 Brahman and tropical composite (average 28% Brahman) female cattle aged between 0.5 and 7.5 years of age at five sites across Queensland. The study validated the subtraction of previously published estimates of gravid uterine weight to correct liveweight to the non-pregnant status. Hip height and liveweight were linearly related (Brahman: P<0.001, R-2 = 58%; tropical composite P<0.001, R-2 = 67%). Liveweight varied by 12-14% per body condition score (5-point scale) as cows differed from moderate condition (P<0.01). Parallel effects were also found due to subcutaneous rump fat depth and eye muscle area, which were highly correlated with each other and body condition score (r = 0.7-0.8). Liveweight differed from average by 1.65-1.66% per mm of rump fat depth and 0.71-0.76% per cm(2) of eye muscle area (P<0.01). Estimated dry matter digestibility of pasture consumed had no consistent effect in predicting liveweight and was therefore excluded from final models. A method developed to estimate full liveweight of post-weaning age female beef cattle from the other measures taken predicted liveweight to within 10 and 23% of that recorded for 65 and 95% of cases, respectively. For a 95% chance of predicted group average liveweight (body condition score used) being within 5, 4, 3, 2 and 1% of actual group average liveweight required 23, 36, 62, 137 and 521 females, respectively, if precision and accuracy of measurements matches that used in the research. Non-pregnant Bos taurus female cattle were calculated to be 10-40% heavier than Brahmans at the same hip height and body condition, indicating a substantial conformational difference. The liveweight prediction method was applied to a validation population of 83 unrelated groups of cattle weighed in extensive commercial situations on 119 days over 18 months (20 917 assessments). Liveweight prediction in the validation population exceeded average recorded liveweight for weigh groups by an average of 19 kg (similar to 6%) demonstrating the difficulty of achieving accurate and precise animal measurements under extensive commercial grazing conditions
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