AIA KE KUMU WAIWAI MA MAKALAWENA: ANALYSIS OF THE NATURAL RESOURCES WITHIN THE MAKALAWENA LOKO WAIʻŌPAE COMPLEX.

Abstract

Loko waiʻōpae (anchialine pools) habitats are tidally influenced, land-locked aquatic habitats with subterranean connections to the sea that are home to unique assemblages of organisms, such as the endemic shrimp ʻōpaeʻula (Halocaridina rubra). However, the stability of anchialine environments is threatened by sea level rise, pollution due to groundwater contamination and runoff, as well as disturbance by invasive species. In the present study, I worked with community partners to characterize the Makalawena loko waiʻōpae complex and investigate extrinsic drivers of ʻōpaeʻula abundance. The Kona landscape is marked by ʻaʻā and pāhoehoe lava flows, which has facilitated distinct organic and inorganic succession. I hypothesized that lava flows in Makalawena act as hydrological barriers to isolate loko waiʻōpae from one another. I assigned ponds to regions based on surface lava flow topology: northern ponds dominated by ʻaʻā-lava rock (North), central ponds amongst pāhoehoe-lava rock (Mid), and ponds surrounded by sandy, mixed-rock composition in the south (South). All but two ponds in the Mid region have ʻōpaeʻula predators. Our data indicate that the Makalawena loko waiʻōpae complex partitions into two types of water chemistry. North loko waiʻōpae are characterized by higher salinity and lower nutrients, whereas Mid and South loko waiʻōpae have lower salinity and higher nutrients. As high levels of Nitrogen and Phosphorus can be harmful to aquatic life, and ʻōpaeʻula aren’t able to reproduce in high salinity environments, I hypothesized that Nitrogen, Phosphorus, and Salinity would have a negative correlation with ʻōpaeʻula abundance. In the Mid and South regions, ʻōpaeʻula abundance positively correlated with mean phosphate and total dissolved phosphorus concentrations, respectively. Mean nitrate/nitrite and total dissolved nitrogen concentrations negatively correlated with ‘ōpaeʻula abundance in the North and South regions, whereas, they were positively correlated in the Mid region. Salinity was not significant; however, silicate concentrations were positively correlated with abundance in the North and Mid regions. Since the Mid correlation plot showed no negative correlations, and those are the only two ponds without predators, we may be able to say that the negative correlations in the other pond regions are due to predator presence, which would have implications for ʻōpaeʻula management across the complex. Decreases in ʻōpaeʻula abundances are of critical concern to lineal descendants, customary practitioners and loko waiʻōpae caretakers. Informed by practitioner knowledge, we investigated the relationship of ʻōpaeʻula behavior/abundance and natural cycles (tides, moon phase, diel). ʻŌpaeʻula are preyed upon by invasive fish species that are more active during the day, and as mentioned earlier, ʻōpaeʻula are not able to reproduce in high salinity environments, yet oral reports have stated that they emerge to mate in the pools during certain moon phases. Therefore, I hypothesized ʻōpaeʻula abundance would be highest at night, during low tides, and during full moons. Our data indicate that ʻōpaeʻula prevalence is highest at night but are not affected by tidal phase or moon phases. Understanding the relationship of these factors to ʻōpaeʻula abundance will be critical as Hawaiʻi’s coastal zones experience increasing salt water intrusion and nutrient influences. Moreover, as these shrimp are highly valued as superior palu (chum/bait) to catch ʻōpelu (mackerel scad, Decapterus macarellus), understanding ʻōpaeʻula abundance is intimately linked to perpetuation of Native Hawaiian fishing practices along the North Kona coast. Our observations will inform development of ʻōpaeʻula monitoring and harvesting approaches for ʻōpelu fishing.