Understanding regional migration, residency dynamics, and associated trophic ecology can inform recovery strategies for pelagic species such as Pacific bluefin tuna Thunnus orientalis (PBFT). PBFT residency duration in the eastern Pacific is uncertain, particularly for larger individuals (here, >100 cm or ~3+ years of age). We applied a previously tested “chemical tracer toolbox (Fukushima-derived radiocesium and 13C and 15N stable isotope signatures) to examine migratory and residency patterns and dietary inputs of 428 age 1–6+ PBFT, collected from 2012 to 2015 in the eastern Pacific Ocean. Age 1–3 individuals were a mix of residents and recent (≤ 500 d) migrants, while 98% of age 3–4 and 100% of age 4–6.3 years old PBFT were resident for >500 days in the eastern Pacific. Zooplanktivorous forage (e.g., sardine, anchovy, pelagic red crab, and trophically similar species) of the California Current Ecosystem constituted 57–82% of diet across PBFT sizes. Migration timing estimates show that PBFT may spend two to five years in the eastern Pacific Ocean before returning to the western Pacific.
Marine primary production is a fundamental component of the Earth system, providing the main source of food and energy to the marine food web, and influencing the concentration of atmospheric CO 2 (refs 1,2). Earth system model (ESM) projections of global marine primary production are highly uncertain with models projecting both increases3, 4 and declines of up to 20% by 21005, 6. This uncertainty is predominantly driven by the sensitivity of tropical ocean primary production to climate change, with the latest ESMs suggesting twenty-first-century tropical declines of between 1 and 30% (refs 5,6). Here we identify an emergent relationship7, 8, 9,10, 11 between the long-term sensitivity of tropical ocean primary production to rising equatorial zone sea surface temperature (SST) and the interannual sensitivity of primary production to El Niño/Southern Oscillation (ENSO)-driven SST anomalies. Satellite-based observations of the ENSO sensitivity of tropical primary production are then used to constrain projections of the long-term climate impact on primary production. We estimate that tropical primary production will decline by 3 ± 1% per kelvin increase in equatorial zone SST. Under a business-as-usual emissions scenario this results in an 11 ± 6% decline in tropical marine primary production and a 6 ± 3% decline in global marine primary production by 2100.
Understanding the underlying causes of SCUBA diver contact with sensitive benthic organisms is critical for designing targeted strategies to address and manage diver impacts. For the marine tourism industry to maintain or expand current levels of recreational diving practices, ecologically sustainable management of dive sites is required. This study surveyed 400 SCUBA divers engaged in recreational diving in the subtropical reefs off eastern Australia. A combination of in-water observational research was conducted, with post-dive questionnaires. Linear regression techniques were employed to identify the variables that correlate the frequency of diver contacts with reef biota. Of the 17 variables tested, nine were found to significantly influence contact frequency. These were: the number of days since a diver's last dive, location of original certification, awareness and understanding of marine park zoning (3 variables), site selection, use of photographic equipment, total number of dives logged and diving depth. These results show that while a diver's long-term and recent experience can play a role, awareness of marine park regulations and unidentified differences in prior training (related to location) are also important, suggesting that education and training may provide viable alternatives to limiting diver access at sensitive locations.
Resource managers and policy makers have long recognized the importance of considering fisheries in the context of ecosystems; yet, movement towards widespread Ecosystem-based Fisheries Management (EBFM) has been slow. A conceptual reframing of fisheries management is occurring globally, which envisions fisheries as systems with interacting biophysical and human subsystems. This broader view, along with a process for decision making, can facilitate implementation of EBFM. A pathway to achieve these broadened objectives of EBFM in the U.S. is a Fishery Ecosystem Plan (FEP). The first generation of FEPs was conceived in the late 1990s as voluntary guidance documents that Regional Fishery Management Councils could adopt to develop and guide their ecosystem-based fisheries management decisions, but few of these FEPs took concrete steps to implement EBFM. Here, we emphasize the need for a new generation of FEPs that provide practical mechanisms for putting EBFM into practice in the U.S. We argue that next-generation FEPs can balance environmental, economic, and social objectives—the triple bottom line – to improve long-term planning for fishery systems.
Coral reefs are degraded by the synergistic action of climate and anthropogenic stressors. Coral cover in the Palk Bay reef at the northern Indian Ocean largely declined in the past decade due to frequent bleaching events, tsunami and increased fishing activities. In this study, we carried out a comparative assessment to assess the differences in the recovery and resilience of three spatially distant reefs viz. Vedhalai, Mandapam and Pamban along Palk Bay affected by moderate, severe and low fishing pressure respectively. The assessment was based on the juvenile coral recruitment pattern and its survivability combined with availability of hard substratum, live coral cover and herbivore reef fish stock. The Vedhalai reef has the highest coral cover (14.6 ± 6.3%), and ≥90% of the live corals in Vedhalai and Mandapam were affected by turf algal overgrowth. The density of herbivore reef fish was low in Vedhalai and Mandapam reefs compared to the Pamban reef with relatively few grazing species. The juvenile coral diversity and density were high in the Pamban reef and low in Vedhalai and Mandapam reefs despite high hard substratum cover. In total, 22 species of juvenile corals of 10 genera were recorded in Palk Bay. Comparison of the species diversity of juvenile corals with adult ones suggested that the Pamban reef is connected with other distant reefs whereas Vedhalai and Mandapam reefs were self-seeded. There was no statistically significant difference in the survivability of juvenile corals between the study sites, and in total, ≥90% of the juvenile corals survived the high sedimentation stress triggered by the northeast monsoon and bleaching stress that occurred recurrently. Our results indicated that the human activities indirectly affected the juvenile coral recruitment by degrading the live coral cover and contributed to the spatial variation in the recovery and resilience of the Palk Bay reef. Low species diversity of the juvenile corals will increase the vulnerability of the Palk Bay reef to species-specific endemic threats.
1. Birds breeding on ocean beaches are threatened globally, often requiring significant investments in species conservation and habitat management. Conservation actions typically encompass spatial and temporal threat reductions and protection of eggs and broods. Still, populations decline or recover only slowly, calling for fresh approaches in beach-bird conservation.
2. Because energetic demands are critically high during nesting and chick rearing phases, and chick survival is particularly low, supplementing prey to breeding birds and their offspring is theoretically attractive as a means to complement more traditional conservation measures.
3. Prey for plovers and similar species on ocean beaches consists of invertebrates (e.g. small crustaceans, insects) many of which feed on stranded masses of plant material (e.g. kelp and seagrass) and use this ‘wrack’ as habitat. We added wrack to the upper beach where plovers nest and their chicks forage to test whether algal subsidies promote the abundance and diversity of their invertebrate prey.
4. Adding wrack to the upper beach significantly increased the abundance and diversity of invertebrate prey items. At wrack subsidies greater than 50% of surface cover invertebrate assemblages became highly distinct compared with those that received smaller additions of wrack. Substantial (2–4 fold) increases in the abundance amphipods and isopods that are principal prey items for plovers drove these shifts.
5. This proof-of-concept study demonstrates the feasibility of food provisioning for birds on ocean shores. Whilst novel, it is practicable, inexpensive and does not introduce further restrictions or man-made structures. Thus, it can meaningfully add to the broader arsenal of conservation tools for threatened species that are wholly reliant on sandy beaches as breeding and foraging habitats.
It is widely acknowledged that family and care-giving responsibilities are driving women away from Science, Technology, Engineering, and Mathematics (STEM) fields. Marine mammal science often incurs heavy fieldwork and travel obligations, which make it a challenging career in which to find work-life balance. This opinion piece explores gender equality, equity (the principles of fairness that lead to equality), and work-life balance in science generally and in this field in particular. We aim to (1) raise awareness of these issues among members of the Society for Marine Mammalogy; (2) explore members’ attitudes and viewpoints collected from an online survey and further discussion at a biennial conference workshop in 2015; and (3) make suggestions for members to consider for action, or for the Board of Governors to consider in terms of changes to policy or procedures. Leaks in our pipeline—the attrition of women, and others with additional caring responsibilities—represent an intellectual and economic loss. By striving for equity and promoting work-life balance, we will help to ensure a healthy and productive Society better able to succeed in its aims promoting education, high quality research, conservation, and management of marine mammals.
Nature reserves are created to conserve biodiversity and restore populations of harvested species, but it is not clear whether this strategy is successful in all ecosystems. Reserves are gazetted in estuaries to offset impacts from burgeoning human populations, however, coastal conservation cannot be optimized because their effectiveness is rarely evaluated. We surveyed 220 sites in 22 estuaries in the Moreton Bay Marine Park, Queensland, Australia, including all six current estuarine marine reserves within the park. Fishes were surveyed using one hour deployments of baited remote underwater video stations twice at each site over consecutive days. We show that although the estuarine reserves in Moreton Bay contain a significantly different fish community, they fail to enhance the abundance of harvested fish species. We posit that performance is limited because reserves protect unique spatial features, or conserve narrow estuaries with weak connections to mangrove habitats and the open sea. Consequently, reserves as currently positioned protect only a subset of potential environmental conditions present for fish within the region, and potentially support residual estuarine habitats (i.e. expansive intertidal flats or shallow creeks) which are not particularly significant to either fish or fishers. We argue that reserve effectiveness can be improved by conserving deeper estuaries, with diverse habitats for fish and strong connections to the open sea. Without incorporating these critical spatial considerations into estuarine reserve design, estuarine reserves are doomed to fail.
Sociological critiques of scientific research processes and their application have developed nuanced understandings of the social, cultural and political forces shaping relationships between science and decision-making. Simultaneously, environmental researchers have sought to construct more engaged, dynamic modes of conducting research to facilitate the application of science in decision-making and action. To date, however, there are relatively few theoretically-oriented approaches that have been able to draw productive connections between the sociological critique and the practical applications that can aid in navigating this complex and diverse milieu. In this article, we propose that the concept of “knowledge governance” can bring together targeted inquiry into the socio-political context in which environmental science is situated, alongside analysis of specific interventions that change knowledge-to-action relationships. Drawing together Jasanoff’s (2005) concept of civic epistemology with Cash et al.’s (2003) knowledge systems for sustainability approach, this knowledge governance inquiry framework offers an integrative lens through which to critically reflect on knowledge-based processes, and incorporate that deeper understanding into intervention efforts. We briefly illustrate its application with reference to a pilot project examining conservation decision-making in the Western Pacific island nation of Palau.
Managers of marine protected areas (MPAs) are constantly challenged to encourage positive user behaviour to minimise impacts on marine ecosystems while allowing recreational use. Yet, some marine users continue to act in ways that diminish conservation values of the area. Drawing on social psychological theories, this paper presents a case for informed behaviour change strategies to reduce problem behaviours in MPAs and contribute to conservation efforts. Social psychological drivers of behaviour are explained and applied to an MPA context to demonstrate how they can inform strategies for predicting and changing behaviour using persuasive communication. As behavioural and persuasive communication theories are seldom invoked and almost never rigorously applied to MPAs, the review offers new theoretical and practical insights into how they can assist MPA management to target and shift specific behaviours that ultimately support marine park values.