This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Fission-fusion bat behavior as a strategy for balancing the conflicting needs of maximizing information accuracy and minimizing infection risk.

No abstract

Climate change and fishing are two of the greatest anthropogenic stressors on marine ecosystems. We investigate the effects of these stressors on Hawaii's deep-set longline fishery for bigeye tuna (Thunnus obesus) and the ecosystem which supports it using a size-based food web model that incorporates individual species and captures the metabolic effects of rising ocean temperatures. We find that when fishing and climate change are examined individually, fishing is the greater stressor. This suggests that proactive fisheries management could be a particularly effective tool for mitigating anthropogenic stressors either by balancing or outweighing climate effects. However, modeling these stressors jointly shows that even large management changes cannot completely offset climate effects. Our results suggest that a decline in Hawaii's longline fishery yield may be inevitable. The effect of climate change on the ecosystem depends primarily upon the intensity of fishing mortality. Management measures which take this into account can both minimize fishery decline and support at least some level of ecosystem resilience.

No abstract

No abstract

The effective evaluation of trophic interactions in pelagic food webs is essential for understanding food web ecology, conservation biology, and management. We tested the applicability of compound‐specific isotope analysis of amino acids (CSIA‐AA) for (1) characterizing trophic positions (TPs) of nine species from four trophic groups (tunas, squids, myctophids, and euphausiids) within a pelagic food web in the eastern tropical Pacific (ETP) Ocean, (2) evaluating trophic discrimination factors (TDFs) of each trophic group, and (3) detecting spatial changes in TPs and food chain length across a region with heterogeneous productivity. Although δ15N values of bulk tissues generally increased from south‐to‐north, CSIA‐AA revealed that trophic positions were uniform throughout our study area. These results suggest that variability in δ15N values were largely driven by nitrogen cycling dynamics in the ETP, which highlights the importance of these processes for the interpretation of δ15N values in food web studies. Absolute TP estimates were unrealistic for higher‐level species, and TDFs (tunas: 4.0‰, squids: 4.6‰, myctophids: 5.0‰, and euphausiids: 7.0‰) were lower than a widely used ecosystem TDF. We used remotely sensed oceanographic data to evaluate the physical oceanography and biological productivity throughout our study area and found significant relationships between δ15N values, nitrate concentrations, and SST across our study area. We did not find a gradient in phytoplankton cell size co‐occurring with an expected productivity gradient across our sampling region, which substantiated our isotope results indicating non‐significant spatial changes in TP and food chain length across the ETP.

The Clarion Clipperton Zone (CCZ) is a vast area of the central Pacific Ocean where the abyssal seabed is a focus for future polymetallic nodule mining. Broad-scale environmental gradients occur east-to-west across the CCZ seabed, including organic matter supply and nodule abundance, factors that influence benthic faunal community structure and function. A network of protected areas across the CCZ, called Areas of Particular Environmental Interest (APEIs), has been designated to cover this variation. Most previous studies of the benthic environment and megafaunal communities have focussed on the eastern CCZ, leaving the impact of these large-scale gradients unexamined and the network design untested. Seamounts are a further source of heterogeneity in the region. We examined the benthic megafaunal ecology of three APEIs in the western CCZ, spanning a range of environmental conditions. We used a combination of seabed photography and direct sampling to assess the environment and megafauna on the soft sediment habitats on the abyssal plain in three APEIs, and seamounts in two of those APEIs. We found that environmental conditions on abyssal plains differed between the three APEIs in terms of water depth, nodule abundance and coverage, sediment particle size distribution, and estimated organic matter flux. Megafauna were low density and high diversity, with few common morphotypes between sites and many morphotypes being observed only once. Xenophyophores dominated the assemblages. The density and diversity of invertebrates were greater at the sites with lower organic matter inputs and greater nodule abundance. Seamounts in the same APEIs were nodule-free and had coarser sediments than on the plain. Invertebrate megafaunal diversity was lower on the seamounts than on the plains, and most morphotypes recorded on the seamounts were only found on seamounts. Low morphotype overlap also suggests little connectivity between APEIs, and between seamounts and adjacent abyssal plains. Our results provide the first evaluation of the seabed habitats and megafaunal ecology in the western CCZ, highlighting environmental gradients that influence benthic communities, and are important for evaluating the design of the network of protected areas.