Hawaiian Coastal Waters Research Articles

Detection and modeling of Staphylococcus aureus and fecal bacteria in Hawaiian coastal waters and sands.

Microbial pollution of recreational waters leads to millions of skin, respiratory, and gastrointestinal illnesses globally. Fecal indicator bacteria (FIB) are monitored to assess recreational waters but may not reflect the presence of Staphylococcus aureus, a global leader in bacterial fatalities. Since many community-acquired S. aureus skin infections are associated with high recreational water usage, this study measured and modeled S. aureus, methicillin-resistant S. aureus (MRSA), and FIB (Enterococcus spp., Clostridium perfringens) concentrations in seawater and sand at six beaches in Hilo, Hawai'i, USA, over 37 sample dates from July 2016 to February 2019 using culturing techniques. Generalized linear models predicted bacterial concentrations with physicochemical and environmental data. Beach visitors were also surveyed on their preferred activities. S. aureus and FIB concentrations were roughly 6-78 times higher at beaches with freshwater discharge than at those without. Seawater concentrations of Enterococcus spp. were positively associated with MRSA but not S. aureus. Elevated S. aureus was associated with lower tidal heights, higher freshwater discharge, onsite sewage disposal system density, and turbidity. Regular monitoring of beaches with freshwater input, utilizing real-time water quality measurements with robust modeling techniques, and raising awareness among recreational water users may mitigate exposure to S. aureus, MRSA, and FIB. PRACTITIONER POINTS: Staphylococcus aureus and fecal bacteria concentrations were higher in seawater and sand at beaches with freshwater discharge. In seawater, Enterococcus spp. positively correlated with MRSA, but not S. aureus. Freshwater discharge, OSDS density, water turbidity, and tides significantly predicted bacterial concentrations in seawater and sand. Predictive bacterial models based upon physicochemical and environmental data developed in this study are readily available for user-friendly application.

Alatina alata box jellyfish monthly migrations in Hawai’i: Lunar and physical oceanographic triggers

Alatina alata, a species of box jellyfish, is found in distinct localities throughout tropical zones in the Atlantic, Pacific, and Indian Oceans, and is responsible for the most severe stings reported in Hawaiian coastal waters. Alatina alata is unique among species of box jellyfish (Cubozoa) in that it is only observed in shallow shoreline waters during lunar period-specific monthly mass aggregations and beaching events, which occur 8–10 days after each full moon. At other times of the lunar cycle, this species has been documented in pelagic zone surveys and is not observed close to shore (0 to 5 meter deep area, 0–100 m from shoreline). To assess potential ecological and environmental triggers for the synchronized shoreward migration behavior of Alatina alata, we investigated 14 years of beach count data in relation to lunar transit, luminosity, tides, and ocean currents using: a 14-year time series of Alatina alata pre-dawn counts; morphometric and reproductive status analyses; three full-transect nighttime shipboard observations; modeling studies; and additional supporting data. Model simulations show a persistent anticyclonic eddy in the study area, which may act as a source point for the jellyfish. Additionally, in situ night-long observations over three separate months revealed for the first time that Alatina alata actively swam en masse from over one mile offshore towards the shore before moonrise. Over 500 animals were observed and all showed strong shoreward swimming behavior perpendicular to the prevailing current. While the monthly populations each demonstrated heterogeneity with regard to size and beaching time, there was a slight trend towards the beaching of larger jellyfish first. Despite this heterogeneity in size, all animals were sexually mature adults replete with gametes or freshly spent. For the first time, we document that a key number of hours of darkness between twilight and moon rise correlate with the migration, and we hypothesize that this lunar cycle specific event triggers gonadal maturation in adult jellies, and maturation then triggers migrations to the shallow reef zone for spermcast mating.

Wintertime Easterly and Southeasterly Airflow in the ‘Alenuihāhā Channel, Hawaii

Abstract During the wintertime, easterly (E) to southeasterly (SE) flow in the Hawaiian coastal waters is frequent. These wind regimes alter the location and magnitude of channel and tip jet accelerations and the orientation and horizontal extent of the wake zones from east-northeast (ENE) trade wind conditions. The differences are the result of changes in orographic blocking by the Big Island and Maui, with respect to the prevailing wind. During an E wind event, the fastest winds over the ‘Alenuihāhā Channel (>9 m s−1) occur in the channel exit with sinking of the inversion, which rises again downstream. Although the upstream wind speed is similar to typical summer ENE trade winds (7–8 m s−1), the maximum channel wind speed is 3–4 m s−1 slower in the exit. The SE flow is characterized by maximum (~6 m s−1) northeasterly (NE) channel winds along Maui’s south shore and at the channel exit. These winds are the result of orographic blocking on the eastern end of Maui as the northwestern tail of a tip jet off the northeastern coast of the Big Island impinges on Mount Haleakalā. Channel wind speeds are modulated by the speed and direction of this tip jet, which itself varies diurnally and throughout the approach of a midlatitude cold front. Removal of the Big Island shows how the tip jet speed and orientation modulate the pressure gradients and winds in the ‘Alenuihāhā Channel. Removal of the Maui County terrain reveals the impact of orographic blocking on the occurrence of channel winds off Maui’s south shore.

Comparative time-courses of photoacclimation by Hawaiian native and invasive species of Gracilaria (Rhodophyta)

Invasive seaweeds have rapidly increased in global distribution and abundance in recent years, presenting significant threats to nearshore ecosystems. Developing characteristics diagnostic of potential macroalgal invasiveness is an important step in controlling their spread. Studies have identified photoacclimation, the ability of the photosynthetic apparatus to adjust to changes in light, as one important attribute in the success of several invasive terrestrial and marine plants; several studies indicate that the rate of photoacclimation plays a role in the differential success of invasive plants at the expense of natives. In this experiment, we compare two closely related species that occur in Hawaiian coastal waters with similar distribution, habitat, and morphology, the invasive Gracilaria salicornia, and the native G. coronopifolia. Samples were grown in outdoor culture, acclimated to one of two irradiance regimes, and reciprocally transplanted. Photoacclimation rates were assessed using in vivo spectrophotometry and PAM fluorometry. Results indicate that G. salicornia has remarkable tolerance to irradiance extremes and experiences rapid growth when transplanted from low to high photosynthetic photon flux density environments, and that differential rates of overall photoacclimation are insufficient to explain the relative success of these two plants. Photoacclimation is achieved via several complex processes that do not necessarily occur contemporaneously. Future researchers should be wary of assuming its completion based on single indicators.

Clostridium perfringens testing improves the reliability of detecting non-point source sewage contamination in Hawaiian coastal waters compared to using Enterococci alone

Non-point sources of sewage-related pollution in tropical marine waters are difficult to ascertain. Enterococci (ENT) are widely used as indicators of human waste but their efficacy in tropical waters is highly debated due to natural presence in tropical soils. Clostridium perfringens (CP) is often used as a secondary indicator of fecal contamination because its presence indicates sewage, and in tropical waters environmental sources are unlikely. We analyzed a 27-year dataset containing over 29,000 samples collected by the State of Hawaii, to determine a proposed CP standard for detecting human sewage, which has applicability throughout tropical marine waters globally. Measured ENT concentrations were highly correlated with turbidity. In three instances, sewage contamination was not detected by ENT samples alone, and impairments from non-point pollution may be highly misinformed in Hawaii. The EPA should examine relationships between CP and human health and implement CP as the primary FIB in tropical marine waters.

Sediment Biogeochemistry of Mesophotic Meadows of Calcifying Macroalgae

Mesophotic (low light) sands were studied in Hawaiian coastal waters (39–204 m water depth) from O‘ahu to Kaho‘olawe by sampling inside and outside of extensive macroalgal meadows of chlorophytes Halimeda kanaloana and Udotea sp. during September 2004, December 2004, and November 2006. Porewater nutrient concentrations in these permeable sediments were comparable to those in nearshore sands and were highly elevated at sediment depths available to holdfasts of some algae (5–10 cm); maximum levels were 3.0 µM reactive phosphorus, 33 µM nitrate, 0.70 µM nitrite, 38 µM ammonium, and 130 µM silicic acid. Benthic material is calculated to be the major source of organic matter driving diagenesis in these sediments. Vegetated sediments appeared more oxidizing than unvegetated sediments, and the presence of macroalgae, particularly Halimeda, was generally associated with higher sediment dissolved inorganic carbon levels. Halimeda-vegetated sediments generally had low dissolved inorganic nitrogen (DIN) levels compared to the Udotea-vegetated and non-vegetated sediments, consistent with the net N loss indicated by sediment stoichiometric relationships. In contrast, Udotea-vegetated sediments showed minimal apparent algal DIN uptake.

Oahutanais makalii , a new genus and species of colletteid tanaidacean (Crustacea, Peracarida) from shelf-waters off Hawaii, with a taxonomic key

A new colletteid tanaidacean, Oahutanais makalii gen. et sp. n., is described from Hawaiian coastal waters at depths ranging from 19 to 102 m. The new taxon is tentatively designated as a new genus, although it displays many features in common with the genus Leptognathiella. The new species is distinguished from the morphologically similar tanaidomorphans by having (1) a small body, less than 1.0 mm (reproductively active specimens), (2) a maxillule with two bifid spiniform setae; (3) a maxilliped palp article-2 with geniculate, finely pectinate spiniform seta on sub-distal inner margin, (4) a cheliped attachment ventrally via sclerite not connected to the carapace, and (5) the pereopods 1 to 6 with ischial seta shorter than the merus. A key to the five extant genera of Colletteidae in the North Pacific Ocean is presented herein.

Numerical Simulations and Observations of Airflow through the ‘Alenuihāhā Channel, Hawaii

Abstract During the summer, sustained winds in the ‘Alenuihāhā Channel, Hawaii, may exceed 20 m s−1 with higher gusts. The Advanced Research Weather Research and Forecasting model is used to diagnose airflow in the Hawaiian coastal waters. High-resolution (2 km) runs are performed for July 2005 covering the ‘Alenuihāhā Channel and nested in a 6-km state domain. Under normal trade wind conditions (7–8 m s−1), winds at the channel entrance are 1–2 m s−1 faster than upstream due to the convergence of the deflected airflows by the islands of Maui and Hawaii, and accelerate through the channel due to along-gap pressure gradients and lower pressure in the wakes of both islands. The acceleration is accompanied by descending airflow (>9 cm s−1) in the exit region with lowering of the trade wind inversion. Deceleration occurs downstream of the channel exit with a rapid change from sinking motion to rising motion (>3 cm s−1). Under normal or strong trade wind conditions, the flow is subcritical [Froude number (Fr) < 1] upstream of the channel, supercritical (Fr > 1) in the exit region, and subcritical again (Fr < 1) downstream with a weak hydraulic jump. The localized sinking motion on the lee side of bordering ridgelines (>1 m s−1) is most significant in the afternoon hours and results in warming and lowering of surface pressure on the lee side, into the channel, and farther downstream. As a result, the channel winds and the wind speed maximum along the southeastern coast of Maui exhibit an afternoon maximum.

Diuron from Maui Sugarcane Field Runoff Is Potentially Harmful to Local Coral Reefs

In a grassroots effort to identify stressors influencing the health of Maui’s coral reefs, samples for the pre- and post-emergent herbicide, Diuron, were taken in July–August 2013, prior to, during, and after the passage of Tropical Storm Flossie on the south central coast of Maui, Hawaii. Diuron is routinely used on sugarcane fields adjacent to Hawaiian coastal waters and is a component of the anti-fouling paint used on small boats. It inhibits photosynthesis of terrestrial plants at concentrations as low as 0.1 parts per billion and can be lethal to endosymbiotic dinoflagellates in corals at concentrations less than 3 parts per billion, a concentration measured in runoff samples taken during this study. While Diuron was not detected in samples taken beyond the coastal outfall or in an adjacent boat basin, this effort provides evidence that a detectable influx of Diuron into Maui’s coastal waters can result from a single rain event. Further, this study will inform efforts to support a ban on the use of Diuron in the wet season and guide monitoring efforts to better understand the effects of Diuron in coastal areas.

Antiviral Activities and Putative Identification of Compounds in Microbial Extracts from the Hawaiian Coastal Waters

Marine environments are a rich source of significant bioactive compounds. The Hawaiian archipelago, located in the middle of the Pacific Ocean, hosts diverse microorganisms, including many endemic species. Thirty-eight microbial extracts from Hawaiian coastal waters were evaluated for their antiviral activity against four mammalian viruses including herpes simplex virus type one (HSV-1), vesicular stomatitis virus (VSV), vaccinia virus and poliovirus type one (poliovirus-1) using in vitro cell culture assay. Nine of the 38 microbial crude extracts showed antiviral potencies and three of these nine microbial extracts exhibited significant activity against the enveloped viruses. A secosteroid, 5α(H),17α(H),(20R)-beta-acetoxyergost-8(14)-ene was putatively identified and confirmed to be the active compound in these marine microbial extracts. These results warrant future in-depth tests on the isolation of these active elements in order to explore and validate their antiviral potential as important therapeutic remedies.

Molecular characterization of the spatial diversity and novel lineages of mycoplankton in Hawaiian coastal waters

Microbial community diversity and composition have critical biogeochemical roles in the functioning of marine ecosystems. Large populations of planktonic fungi exist in coastal ocean waters, yet their diversity and role in carbon and nutrient cycling remain largely unknown. Lack of information on critical functional microbial groups limits our understanding of their ecological roles in coastal oceans and hence our understanding of its functioning in the ocean's carbon and nutrient cycles. To address this gap, this study applied the molecular approach denaturing gradient gel electrophoresis (DGGE) coupled with clone library construction to investigate mycoplankton communities in Hawaiian coastal waters. Mycoplankton communities displayed distinct lateral and vertical variations in diversity and composition. Compared with the open ocean, surface (<100 m) near-shore waters had the greatest diversity and species richness of mycoplankton, whereas no differences were found among stations at depths below 150 m. Vertical diversity profiles in the coastal waters suggested that diversity and species richness were positively correlated to phytoplankton biomass in the coastal waters, but not in offshore waters. A total of 46 species were identified and belonging to two phyla Basidiomycota and Ascomycota, with the basidiomycetes as the dominant group (n=42). The majority (n=27) of the basidiomycetes are novel phylotypes showing less than 98% identity in the 18S rRNA gene with any sequence in GenBank. This study provides insight into mycoplankton ecology and is the first molecular analysis of planktonic fungi in the oceans.

Host introduction and parasites: a case study on the parasite community of the peacock grouper Cephalopholis argus (Serranidae) in the Hawaiian Islands

The peacock grouper (Cephalopholis argus) was intentionally introduced to the Hawaiian coastal waters 50 years ago to enhance the local fisheries. Following introduction, this species spread rapidly and became extremely abundant. A comparison of the metazoan parasite community of C. argus was performed between its native range (Moorea Island, French Polynesia) and its introduced range (Oahu and Big Island, Hawaii). Polynesian groupers were infected with a highly diversified parasite community whereas Hawaiian groupers exhibited a depauperate ensemble of parasite species, C. argus having lost most of the parasites common in their native range. Interestingly, the grouper has not acquired new parasites present in Hawaiian waters. This study provides the first field evidence of significant parasite release in a wild but previously introduced fish in coral reefs and is discussed in relation to the Enemy-Release Hypothesis which has never been assessed in those ecosystems.

A survey of epiphytic dinoflagellates from the coastal waters of the island of Hawai‘i

Three hundred and sixty-nine macroalgal and non-algal samples were collected from six coastal sites around the island of Hawai‘i on a biweekly basis over a 1-year period to ascertain (1) the presence of potentially toxigenic benthic dinoflagellates, and (2) substrate and environmental preferences of the dinoflagellates. Twenty-six genera/species of dinoflagellates were encountered including the (potentially) toxigenic species Amphidinium sp., Coolia monotis, Gambierdiscus sp., Ostreopsis ovata, Prorocentrum concavum, Prorocentrum hoffmannianum, Prorocentrum lima, and Prorocentrum mexicanum. Twenty of the species are being reported for the first time as present in Hawaiian coastal waters. There was some evidence of macroalgal host preference (e.g., C. monotis on Tolypiocladia glomerulata), although host morphology preferences was greater (e.g., Gambierdiscus sp., and P. lima on filamentous turfs; O. sp. 1 on sheet-like macroblades). While some dinoflagellate groups were significantly correlated with nutrient concentrations (e.g., total dinoflagellates with nitrate + nitrite and phosphate concentrations), others were not (e.g., Gambierdiscus sp., Prorocentrum emarginatum, P. lima, and Sinophysis microcephalus). The presence of several potentially toxigenic dinoflagellate species in Hawai‘i merits future study on possible impacts of these dinoflagellates on coastal food webs and human health.

The ultrastructure of nematocysts from the fishing tentacle of the Hawaiian bluebottle, Physalia utriculus (Cnidaria, Hydrozoa, Siphonophora)

Fishing tentacle nematocysts of the hydrozoan, Physalia utriculus, from Hawaiian coastal waters, were examined by light microscopy, as well as by scanning and transmission electron microscopy (SEM and TEM). Hawaiian P. utriculus has been assumed to be conspecific with the Australian morph based on general macroscopic descriptions. Ultrastructural examination using SEM and TEM revealed that the cnidome was composed of two sizes of heterotrichous anisorhizas as well as rare rhopoloids (less than one observed per 1000 nematocysts). Beyond classification of the cnidome of Hawaiian P. utriculus, an unprecedented morphological structure was observed. Specifically, SEM revealed fibers (<1 μm in diameter) along the spiral crest of spines of some discharged tubules of P. utriculus anisorhizas. A hypothetical model of spine morphogenesis was formulated based on comparative analysis of hundreds of discharged tubules.

Bioavailability of inorganic and organic phosphorus compounds to natural assemblages of microorganisms m Hawaiian coastal waters

Bioavailability of inorganic and organic phosphorus compounds to natural assemblages of microorganisms m Hawaiian coastal waters