Intense El Niño events severely impact seabird populations, often months in advance of peak temperature anomalies. The trophic mechanisms responsible for these impacts are unknown but are assumed to operate at seasonal scales and to be linked to ocean productivity changes. Precursors to El Niño events include changes in both sea-surface temperature and the depth of the 20 degrees C thermocline. Foraging piscivorous seabirds are known to be sensitive to both thermocline depth and sea-surface temperature change, but the potential influence of these phenomena on breeding dynamics is unknown. Using 18 years of data on three seabirds of the western tropical Pacific, we show that pelagic seabird breeding participation is directly and independently related to changes in both surface chlorophyll concentration and thermocline depth that occur well in advance of El Niño generated sea-surface temperature anomalies. In contrast, breeding in an inshore foraging species is not correlated with any environmental/biological parameters investigated. These findings demonstrate that El Niño related phenomena do not affect seabird prey dynamics solely via productivity shifts at seasonal scales, nor in similar ways across different seabird foraging guilds. Our results also suggest that population declines observed in the western tropical Pacific may be directly related to the frequency and intensity of El Niño anomalies over the study period.
Organisms can be strongly affected by a range of natural and anthropogenic stressors in conjunction, making comprehensive assessments of multiple potential drivers of population dynamics essential. An 18-year dataset obtained for Michaelmas Cay in the northern Great Barrier Reef, Australia, was used to assess population trends for three tern species relative to two potential threatening processes, namely human impacts (as either commercial fishing or tourism) and cyclone activity. We found a positive, 2-year lagged relationship between long-line catch per unit effort in the Eastern Tuna and Billfish Fishery in the vicinity of Michaelmas Cay and breeding participation in the two pelagic foraging terns, but not in the inshore foraging tern. The abundance of large pelagic fish may influence recruitment into the breeding populations of the two pelagic terns in the following years through impacts on prey availability. Long-term population trends for all seabirds were not related to localised direct disturbance from cyclones or associated changes in cay size and/ or nesting habitat. Current management protocols in place for the tourism industry at the cay appear to be minimising direct human impacts. Other evidence from this breeding location suggesting that climate variation may be driving foraging success and breeding-population dynamics in the two pelagic terns implies that a precautionary approach is warranted to the management of any potential stressors to birds in this system.
Through the Antarctic Treaty on Environmental Protection all of the Antarctic member nations are required to have in place contingency plans for oil spills including oiled wildlife response. The current risks for marine pollution incidents to the Antarctic environment include refuelling activities associated with Antarctic stations/bases; routine station/base activities; and shipping associated with stations/bases, tourism, commercial fishing and whaling. Between 1981 and 2011 there have been reported 33 spills or near spill incidents associated with the Antarctic marine environment. Wildlife at risk from oil spills include seabirds (flying birds and penguins), pinnipeds and cetaceans. Antarctic and polar environments both provide a number of logistical and practical complications given their climatic and geographic character. The key elements for response actions for Antarctic wildlife identified are divided amongst primary, secondary and tertiary oiled wildlife response activities. Primary activities identified include focussing containment and clean up efforts to protecting wildlife as a priority using tools such as sensitivity mapping, stochastic and real time modelling. Secondary activities specific to individual wildlife groups were identified and included specialised hazing, exclusion and pre-emptive capture mechanisms focussed to the Antarctic environment. Tertiary activities are considered with regards to the real capacity of Antarctic stations to respond, take and rehabilitate oiled wildlife given the Antarctic environment and its limitations. The paper identifies realistic mechanisms and systems considering the climatic, logistical and practical issues of the Antarctic environment. Although specific to Antarctic bases the paper outcomes can be equally applied to other polar environments.
Australia holds regular National oil spill exercises through the National Plan for Maritime Emergencies. Two National Plan exercise activities that have taken place include Exercise Northerly held in Darwin (Northern Territory) in 2014 and Exercise Torres focussed on the Torres Straits (Queensland) in 2018. The overall aim of the two exercises were to implement and review the effectiveness of a combined Commonwealth (Federal), Territory/State and industry marine pollution response to a Level 3 pollution incident. Both Exercise Northerly and Exercise Torres included oiled wildlife response actions to practice and test. Exercise Northerly for wildlife was principally a desk top activity that included a number of injects relating to wildlife threatened and impacted by an oil spill event. Wildlife considered in Northerly included cetaceans, dugong, marine reptiles and seabirds. The key wildlife objectives for Northerly were to establish and maintain a wildlife Incident Management Team under the broader Incident Command structure and develop wildlife incident action plans for hazing wildlife and responding to oil impacted wildlife. Exercise Torres incorporated both planning and field based operational activities and considered cetaceans, dugong, marine reptiles and seabirds both threatened and impacted by oil pollution. Wildlife planning during exercise Torres was principally held in Cairns at the established Incident Control Centre where incident action plans were developed to haze oil threatened wildlife, collect oiled impacted wildlife and then rehabilitate wildlife considering the strict quarantine restrictions imposed on wildlife movements through and out of the Torres Strait Protection Zone. The field deployment activities for Torres were then managed and undertaken through a forward operations base established on Waiben Island, some 800 kilometres or 500 miles north of Cairns that borders Papua New Guinea. The wildlife field teams were required to establish an oiled wildlife response centre making it fully operational with pre-deployed equipment, manage responder safety for actual dangerous wildlife in the area, respond to reports of impacted wildlife, transport impacted mock wildlife through the different contaminant hazard zones (i.e. hot, warm and cold zones) and then to the wildlife care centre, undertake wildlife assessment using narrative techniques, triage wildlife based on provided wildlife assessment data, decontaminate mock wildlife and then provide basic wildlife rehabilitation practices. Both of the National exercises provided effective opportunities to practice the skills necessary to support oiled wildlife response actions and to identify key learnings for better practices when responding to oiled wildlife threatened and impacted in remote areas.
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