Thread by @ExplorerWieteke

Our research about comparing #arthropod 🪳 communities between islands🏝️with and without house mice🐁on #MidwayAtoll #Pihemanu #Kuaihelani is published! 🥳🎉muse.jhu.edu/article/805231
A thread on what we found out🧵

(Photo credit: Forest & Kim Starr; image shows Protaetia pryeri)

1. Arthropods perform key roles in ecosystem processes on islands, especially on seabird islands where they affect nutrient cycling and disposition. But, what happens when these arthropod communities 🐜🕷️🪰🪲🦗are subject to a novel predator, such as house mice? 🐭

2. Mice are slated for eradication on Midway Atoll NWR once it was discovered that they were attacking and killing nesting albatross😟However, how will Midway's arthropod communities respond or recover once mice are gone? How do communities differ where mice are/aren't present?🧐

3. We monitored ground-dwelling arthropod communities via pitfall traps from April 2018 to February 2020, across Midway Atoll's two main islands🏝️: Sand Island (where mice are present 🐭) and Eastern Island (where mice are absent ✖️). Can you guess how many arthropods we counted?

4. 451,752!
We counted and identified nearly half a million arthropods to order. Overall, Midway Atoll's arthropod communities are dominated by Hymenoptera🐜 Collembola, Isopoda, Amphipoda, Coleoptera 🪲 and Diptera 🪰 But arthropod communities differ strongly between islands...

5. Midway Atoll's arthropod communities form different groups, each characterized by different arthropod orders. Sand🏝️= ticks, earwigs, crickets, flies, and amphipods, and spiders. Eastern🏝️= ants, pseudoscorpions, beetles, collembola, and moths.

6. Moreover, diversity of arthropods (by order) is significantly higher on Sand Island and there are many differences in arthropod communities between habitats, too.

7. So, what does this all mean? And why would we care?
Overall, we don't have a thorough understanding of what arthropods do on islands--and, in the context of rodent eradications, we don't really know how arthropod communities respond or recover.

8. Although this is a pre-eradication study, the arthropod communities on Eastern 🏝️ can help us to predict what might happen on Sand Island. Eastern 🏝️ is characterized by larger, slower-moving insects like moths and beetles, that are far less abundant on Sand 🏝️, which are...

9. ... also the same arthropod taxa that are typically consumed by mice. So, some of the differences that we see between these islands could be due to mice predation! 🐭 And, in turn, we might expect populations of these taxa, like moths and beetles, to recover on Sand 🏝️

10. But, many of the differences in arthropod communities between islands could be due to differences in land-use history (Sand🏝️ has a harbor, Eastern🏝️doesn't) as well and different rates of species introductions to the islands. Consider this...

11. During the early 20th century, 9,000 tons😮of topsoil were imported from Hawaii and Guam to Sand Island to create a 3-acre vegetable garden; in the process, 100s of arthropod species were introduced!

12. So, the increased diversity and more complex arthropod community structure on Sand🏝️could be a form of "ecological inheritance." It goes to show that it's really important to consider history of a layered landscape in the context of restoration and conservation.

13. This is just the start! Our study gives baseline information about Midway's arthropod communities in the presence of an invasive, mammalian predator, which can help us to better understand how island entomofauna respond and recover after rodent eradications.

Mahalo😊 And stay tuned for more exciting research about... what mice are eating on Midway!
Thank you to our funders and supporters: @NIUlive @NSF @USFWSPacific
@DocHPJones @Kaylee_rosen @NoExtinctions