Now You Sea 'Em...

There is a seahorse in this picture. (Photo credit: Beth Deacy, LAIP intern)

Photo credit: Beth Deacy.

In the last few weeks, we've seen a number of seahorses in the fishpond. They're probably Hippocampus kuda (Bleeker 1852), the smooth seahorse, also sometimes called the yellow seahorse. These little guys are pretty common in Kaneohe Bay, but are usually so covered in sediment and filamentous algae that you don't notice them.

'Aumakua and "Great Change"

It turns out there are far more complex questions we can ask about the shark in the fishpond. No, I didn't see it yesterday, but we saw a good deal of thrashing near the dock and think it may have been snacking there. Let's be honest: It's cool that there is a big shark in a small area that we study. But it is a spiritual event as well as a biological one.
Auntie Donnie, professor in the UH Hawaiian Studies program and cultural teacher for the LAIP interns, gave us a little background yesterday on the shark and other spirits around the fishpond and Kaneohe Bay. When she heard there was a shark in the pond, she thought, "This is heavy." Sharks are one form of an 'aumakua, a guardian spirit. 'Aumakua have connections to certain families, so this shark is related by blood to a family here. Family members can communicate with the 'aumakua and invite them to leave or stay. Additionally, guardian spirits (kia'i) patrol the bay and make sure people are treating the land well, sharing with each other, and working hard (an approximation of the Hawai'ian word for this is pau). These spirits include Meheanu, the kia'i of the fishpond. According to legend, Meheanu brings in a lot of fish if people are pau, but can also take them away.
Auntie Donnie says the last time a shark was in the pond, a great change happened there. This could mean that the pond is already transforming, or that the kiai'i are demanding change. As researchers, we have a responsibility to honor this. So what does it mean to be pau as a scientist? We have to know our place at this site, and our responsibilities as stewards of this valuable resource. So as we look forward to great and exciting changes in the pond, we also recognize that we too have a place in making those changes.

Tiger shark in the fishpond?

Word has it, from POH, that there is a 6-foot tiger shark in the fishpond. It was last seen hanging out at one of the makahas, probably because that's the only place where it's deep enough for it to swim. According to research by Dr. Carl Meyer at French Frigate Shoals in Hawaii (Meyer 2010), tiger sharks use their individual experiences to develop habits for feeding sites, so it may either have visited the pond before, or it may come back later.

Really? How did it even get in there?
This is a good example of an organism you don't want in your pond. Ancient Hawai'ians tried to keep predators out. That said, when the pond was originally built, there probably wasn't a space large enough to let something like that in, so they didn't have to worry about the logistics of removing such a large animal.
We're going to look for it tomorrow. I wonder what it's eating...

Meyer, C., Papastamatiou, Y., & Holland, K. (2010). A multiple instrument approach to quantifying the movement patterns and habitat use of tiger (Galeocerdo cuvier) and Galapagos sharks (Carcharhinus galapagensis) at French Frigate Shoals, Hawaii Marine Biology, 157 (8), 1857-1868 DOI: 10.1007/s00227-010-1457-x

Hungry for the Fruit of the Sea: Missing Shrimp

Glass shrimp ('opae) have been present in the fishpond since I started working here. These little shrimp, which typically measure < 3 cm in length, are important nutrient shunts because they consume microalgae and detritus, grow rapidly, and are a food source for fish and invertebrates. Glass 'opae are so small that you have to dissect a lot of them in order to get enough tissue for a single stable isotope sample, and dissection requires a tiny scalpel and many hours at the microscope. In the fishpond, you can see them grazing in the shallows, and when we used dip nets or seines in the past, the nets came up covered in tiny shrimp-- so many that obtaining the 50-100 shrimp needed for a complete muscle tissue sample was not a difficult task. This past weekend, there were barely any. We used seines and dip nets at four sites across the pond, and the most shrimp we got at a single site was...twelve. This may be a result of heavy rains (salinity patterns in the water can change species distributions), or other changes in water quality. There may also be some seasonality (=change over the seasons) in shrimp populations in the pond. Seasonality in the abundance of certain species in the pond will surely affect the diets of fish and invertebrates, so it's something I'll need to investigate more in my field work.

All Eyes

P. vigil caught near the mangroves in the back of the pond.

This weekend we did a series of seines in the fishpond to catch more Thalamita crabs and glass shrimp ('opae). Usually a few seines at one site can turn up 10 crabs, but this weekend, not so. Why? We kept catching these in our nets. Meet mo'ala, or Podophthalmus vigil, the long-eyed swimming crab. The name "vigil" means "watchful," and probably refers their long eye-stalks. We found tens of these in our seines across the pond, and even a few gravid ones holding eggs. I'm not sure why they were so abundant this month. We also spotted an endemic Hawaiian species, the blood-spotted swimming crab (Portunus sanguinolentus). Surveys by Bob Hiatt in Hawaiian fishponds in the 1940's turned up these same species, which are both eaten by ulua, one of the main predators in the pond.

There is some variation in claw color in P. vigil. Notice the eyes peeking out from behind the chelipeds.

Gravid Rainbow. The panel that holds the eggs next to the body is called the apron, and is wider and rounder in females. It can hold millions of eggs at a time. This crab was caught near the seawall.