Usage of this form is not approved for other program offices.
OMB Approval No. 0648-0384
Expiration Date: 3/31/2013
Format for Project Final Report
I.
II.
III.
IV.
Report Title, Author, Organization, Grant Number (NA09NOS4260242), Date
Estimating the magnitude of the export of dissolved inorganic and organic
nitrogen from Nu‘upia Ponds to Kāne‘ohe Bay, John Stimson and Evelyn Cox,
University of Hawaii, September 2011.
Executive Summary
Although the input of dissolved nutrients to Kāne‘ohe Bay have been estimated,
the magnitude of nutrient input through the tidal exchange of waters between
Nu‘upia Ponds and the South Bay have never been estimated. This project
measured the volume and rate of exchange of waters between these two bodies
and the concentration of nutrients in the two bodies. The net flow of nutrients is
into the Bay and the quantity of dissolved nutrients flowing into the South Bay is
equivalent to that flowing from any of the streams entering the South Bay.
Nutrient inputs to the Bay are of interest because elevated levels of dissolved
nutrients can stimulate micro- and macro-algal growth.
Purpose
A.
Overarching goal(s) of the project
This project had two goals, to estimate the nitrogen input to Kāne‘ohe Bay from
the Nu‘upia Ponds, and to compare the concentration of dissolved and
particulate nutrients in the Ponds to levels measured in 1995/96.
B.
Management problem addressed
The input of nutrients into the Bay from streams has been measured a number
of times in the past but the input from the Ponds through culverts and a canal
have never been measured.
C.
Hypotheses (if applicable) and objectives of the project.
Objectives:
To measure the current concentrations of dissolved inorganic and dissolved
organic nutrients in the waters of the Nu‘upia ponds which border
Kāne‘ohe Bay.
To estimate the input of nutrients from the Ponds to Kāne‘ohe Bay.
To measure the present nutrient levels in the South Bay.
To estimate the direction of the flow of Pond waters once they enter the Bay
Approach
A.
Detailed description of the work that was performed.
1) Concentrations of dissolved inorganic and organic nutrients in the Ponds
bordering Kāne‘ohe Bay were measured weekly.
2) Concentrations of these nutrients in the South Basin of the Bay were
measured weekly.
1
3) The flow rate of water in the culverts and canal connecting the Ponds with the
Bay were measured during various tidal flows.
4) The input of nutrients to the Bay from the Ponds was calculated using the
nutrient concentrations in the Ponds and the flow rates from the Ponds.
5) The direction of movement of surface waters exiting the ponds was measured
with drogues.
B.
V.
Findings
A.
Actual accomplishments and findings.
Concentrations of nitrates and phosphates in the Ponds are about the same as
they were at the same sites 15 years ago, but concentrations of ammonium are
now lower.
Annual outflow, primarily tidally driven, from the Ponds (culverts + canal) into
the South Bay is greater than that of any of the streams draining into the South
Bay.
Nutrient concentrations in the outflow water are greater than that in the South
Bay waters.
The delivery of inorganic nutrients to the Bay from the ponds per year is greater
than the delivery of these nutrients to the Bay by the streams entering the South
Bay.
Drogue studies indicate that water flowing into the Bay from the Ponds is moved
toward the reefs at the SE end of the Bay by the action of the trade winds.
B.
C.
VII.
Project management: List individuals and/or organizations actually performing
the work and how it was done.
John Stimson PI, Zoology Dept., University of Hawai‘i, collected water samples,
measured water levels, performed drogue studies, directed student help
in field surveys.
Evelyn Cox, CO-PI, Math/Science Dept., University of Hawai‘i West O‘ahu,
performed flow measurements, collected water samples, directed
student help.
Karen Bryan, Student help, University of Hawai‘i, performed drogue studies and
collected water samples.
Debra Ford, Student help, University of Hawai‘i, performed drogue studies and
collected water samples.
If significant problems developed which resulted in less than satisfactory or
negative results, they should be discussed.
None
Description of need, if any, for additional work.
There is the need to determine why nutrient concentrations in the outflowing
water of the canal are elevated.
Applications
2
Outputs and management outcomes achieved. Outputs are defined as products (e.g.
publications, models) or activities that lead to outcomes (changes in user knowledge
or action). How did your project benefit resource managers? Has your project lead
to societal improvements?
A. Outputs
i.
New fundamental or applied knowledge: The fact that the output of dissolved
nutrients from the Ponds to the Bay is high will be an important result for
managers to consider.
ii. Scientific publications: None yet.
iii.
Patents:
iv.
New methods and technology
v.
New or advanced tools (e.g. models, biomarkers)
vi.
Workshops: An informational meeting is planned for the Marine Base
environmental office when we receive and analyze the complete set of
nutrient data still to be supplied by our contractor.
vii.
Presentations: to date, HCRI presentations.
viii. Outreach activities/products (e.g. website, newsletter articles)
Presentation of these findings in University of Hawai‘i West O‘ahu classes
(so far, Marine Biology, to come Coral Reefs and Hawaiian Environmental
Biology).
B. Management outcomes - I. Management application or adoption of:
i.
New fundamental or applied knowledge: There is a high input of dissolved
inorganic nutrients from the Ponds to the Bay. The reasons for the high
input should be explored.
ii.
New or improved skills: The project introduced to students to the process of
collecting and analyzing quantitative field data.
iii.
Information from publications, workshops, presentations, outreach products
iv.
New or improved methods or technology
v.
New or advanced tools
C. Management outcomes - II. Societal condition improved due to management
action resulting from output; examples:
i. Improved water quality: When the results are completed, the Marine Corps
environmental office should explore the reasons for the high nutrient
levels in the canal.
ii. Lower frequency of harmful algal blooms: Herbivorous fishes generally are
responsible for controlling algal biomass on reefs. Herbivorous fishes do
not use all reef habitats, particularly reef flats. The algae growing on reef
flats can grow faster if the nutrient concentrations they are exposed to
are elevated. Stimulation of algal growth by elevated nutrients can result
in the production of drift algae which accumulates on reefs.
iii. Reduced hypoxic zone area
iv. Improved sustainability of fisheries
3
D. Partnerships established with other federal, state, or local agencies, or other
research institutions (other than those already described in the original proposal).
The Marine Corps environmental office is responsible for the management of
this Wildlife Management Area. They were interested to learn about the status
of nutrient concentrations in the Pond waters which have not been assessed
since 1996. Their office handled security and logistics issues associated with the
project.
VIII.
Evaluation
Describe the extent to which the project goals and objectives were attained. Provide
explanation for modification of goals and objectives.
All our goals and objectives have been met in terms of field measurements, but
we are still not in receipt of all data on nutrient concentrations which are to be
provided by our contractor.
4
Project Final Report
Introduction
The inputs of dissolved organic and inorganic nutrients, principally compounds containing
nitrogen and phosphorus into Kāne‘ohe Bay, and the concentration of these compounds in the
Bay, have been of interest since the 1970s because of the potential of these nutrients to cause
blooms of microalgae in the water column and to stimulate the growth of macroscopic algae on
reefs. These two phenomena are antithetical to the growth of corals which are responsible for
the growth of reefs in the Bay.
Past studies of nutrient inputs and nutrient levels in the Bay include the paper by Smith et al.
(1981), which documented the magnitude of the influence of discharge of human sewage into
the relatively closed-off waters of the South Bay. Their results included both concentration of
dissolved nutrients in the Bay and the magnitude of inputs from streams. Freeman (1993)
estimated the input of nutrients to the Bay from a variety of sources. Laws and Allen (1996)
considered nutrient concentrations in the Bay more than a decade after diversion of the
sewage discharge. The impact of stream inputs was also measured in the studies of Hoover
(2002), Ringuet and Mackenzie (2005), Cox et al. (2006) and DeCarlo et al. (2007). Since stream
flow is very variable due to the small size of the watershed, the steepness of the watershed and
the intensity of rain storms, a number of studies have also specifically considered the inputs of
individual storms rather than the annual inputs of water and nutrients.
None of these studies have apparently considered the input of nutrients to the Bay through
the connections between the Nu‘upia Ponds and the Bay. There are 3 connections, two sets of
culverts which connect the western most pond, ‘Ekahi, with the Bay, and a canal which
connects Halekou Pond to the Bay. Both these Ponds have connections with ponds further to
the east. Both ‘Ekahi and Halekou are influenced by changes in tide level, and the changes in
the tides generate considerable flow through these connections. A study performed in 1994
and 1995 showed that waters in the Ponds have considerably higher nutrient levels than do
waters of the South Basin of Kāne‘ohe Bay (Cox and Jokiel 1997). The sources of these
nutrients have not been definitely established but include: overflow from the Aikahi sewage
treatment plant into the Ponds, the breakdown of organic matter generated in the ponds or
along their shores and storm drain runoff into the Ponds (AECOS 1989).
Interest in nutrient input into the Bay stems in part from the fact that increased nutrient
concentrations can enhance microalgal and macroalgal growth. This has been shown
experimentally (Larned and Stimson 1996) and can be seen in the response of the macroalga
Dictyosphaeria cavernosa to the shutoff of domestic sewage release into Kāne‘ohe Bay in 1977.
Following the shutoff/diversion of the nutrient rich sewage (6 million gallons a day) the
recovery of D. cavernosa fell dramatically by 1983 (Hunter and Evans 1995). The response of
microalgae, or phytoplankton, is detailed in Laws and Allen (1996) who showed that the size of
algal cells and biomass per unit water volume of phytoplankton diminished following the
sewage diversion. Ringuet and Mackenzie (2005) and Cox et al. (2006) also showed changes in
5
the abundance and composition of the microbial and microplankton communities following
nutrient inputs associated with elevated stream flows into the Bay. The enhancement of
macroalgal growth can create situations in which macroalgae can outcompete corals for space.
Enhancement of phytoplankton growth can make the water column more turbid, reduce
penetration of irradiance and thus restrict the growth or corals.
The questions addressed by this study were: what are the present nutrient levels in the
Ponds, what are the rates of outflow and inflow between the Ponds and the Bay, and what
areas of reef in the SE Bay are downstream from the discharge points of pond water? Once the
rate of outflow from the Ponds to the Bay and the concentration of nutrients in this water are
established, then combining these figures would allow for the estimation of the delivery rate of
nutrients to the Bay. This delivery rate can then be compared with the delivery rate of
nutrients to the Bay by streams feeding into the South Bay. The Pond-Bay connections differed
from the stream–Bay connections in that the former are two way flows induced by tides, so the
net outflow of dissolved nutrients was computed.
Methods
Measurement of inflow and outflow from the Ponds and measurements of dissolved
nutrient concentrations in pond water, were performed at 3 sites, the mouth of the Canal
draining the NW perimeter of the Ponds and Halekou Pond, and the two sets of culverts
draining ‘Ekahi Pond. The southern set of culverts in ‘Ekahi Pond consists of 2 pipes each 60 cm
in internal diameter and is referred to here as site EK1; the northern set of culverts in ‘Ekahi
Pond consists of 3 pipes each 122 cm in diameter and is referred to here as EK2.
Inflow to the ponds and outflow from the Ponds to the Bay were measured with a Sontek
acoustic Doppler flow meter (Flow Tracker). This device was used to measure flow rates in a set
of points in the plane of the cross section of the flow. The width of the flow and a depth profile
are entered into the device, flow speeds are measured at the points in the plane, and the meter
yields a flow rate in cubic meters per second. Flow rates are dependent on tide heights in the
Bay and the tide heights reported here are in meters above or below MLLW, as reported by
NOAA. Flow rates were measured at a range of tidal heights.
Water samples were collected in the ponds at sites established in 1994 for the analysis of
dissolved organic and inorganic nitrogen and phosphorus. The concentrations in these samples
were used in two ways: they were used to determine how concentrations in the ponds
compared with those measured in 1994/1995/1996, and they were used to estimate the
quantity of nitrogen exported from the ponds on a yearly basis. Concentration values
measured on outgoing tides were used to generate estimates of nutrient discharge to the Bay,
and concentration measured on incoming tides were used to measure nutrient input to the
ponds. Water samples were sent to the University of Washington Technical Services, Marine
Chemistry Lab, for the analysis of NO3, NO2, NH4, PO4, Silicate. Additional samples were taken
from the south Basin of Kāne‘ohe Bay to represent the concentrations of these nutrients in the
receiving waters.
6
Drogues were used to determine how discharged pond water moved once it entered the
Bay. The drogues were one gallon plastic bottles weighted so that their caps were at the water
surface. Attached to the cap was a 20 cm tall wire post which served as a mast for a flag made
of surveyors tape. This design of drogue was used in order that the drogue could pass over
shallow reef flats on most tides.
Results
Outflow rates from the canal and culverts were relatively independent of the tide height in
the Bay, but outflow did not begin until the tide height dropped below a particular sill height for
each structure. As can be seen in Figure 1 for one of the 3 1.2 m culverts at the northern
culvert site in ‘Ekahi Pond, the sill height was about 0.4 m for these culverts: above this tide
height water entered the pond at increasingly greater rates with greater tidal heights. The
relative independence of outflow rates from tide heights is the result of the small changes in
tide height in ‘Ekahi pond, a range of about 20 cm compared with a tidal range in the Bay of
about 1.05 m.
Figure 1: Flow rates measured at the northern culvert site connecting ‘Ekahi Pond to the Bay. Data are
for one of the 3 culverts at this site.
Outflow (m3sec-1) from the Canal was dependent not only on the tide height in the Bay but
also on whether the tide was rising or falling (Figure 2). If the tide was rising, the difference
between the tide height in the Canal–Pond unit and the Bay was less, and therefore inflow
started at a lower tide height. If the tide level was falling, inflow required a greater tide height.
Flow rates out of the canal are on the order of 1.5 m3sec-1(Fig. 2). Outflows on falling tides
were greater than outflows during rising tides. The combined flow out of the 3 northern ‘Ekahi
culverts is only about 0.15 m3sec-1, and the flow out of the 2 southern culverts of ‘Ekahi Pond is
7
about 0.002 m3sec-1 .
Figure 2: Flow rates at the mouth of the Nu‘upia Canal.
Concentrations of dissolved inorganic nitrogen in the waters flowing out of the Canal and out
of the Pond culverts were substantially higher than those measured in the waters of the South
Bay in 2010/11 (One Way ANOVA on natural log transformed concentrations): this can be seen
by comparing the means on the 2010/11 lines for NO3/NO2 and NH4 at EK1, EK2 and Canal with
the South Bay mean (Table 1). However the PO4 concentrations in 2010/ 11 in the ‘Ekahi and
Canal outflows are apparently not different from those in the South Bay.
Between year comparisons by t tests show that the concentration of NH4 in ‘Ekahi Pond is
now significantly lower than it was in 1995/96, possibly due to alterations of the pond wetlands
through removal of mangroves in 1995 (Tab. 1). NO3/NO2 and PO4 concentrations in the Ponds
do not differ between time intervals.
8
Table 1: Comparison of inorganic nutrient levels in water bodies involved in this study. Data of
1994/95/96 from Cox and Jokiel (1997. Values from Te (2001) are for 1995/96. Te data (*) are for a
one year period, other data are from the period January through July. Statistical comparisons made on
the natural log transformed values.
NO3/NO2
1995/96
2010/11
NH4
1995/96
2010/11
PO4
1995/96
2010/11
EK1
EK2
mean
std. dev.
N
0.56
1.22
31
0.60
1.14
31
mean
std. dev.
N
0.70
1.28
27
ns
0.49
0.85
27
ns
mean
std. dev.
N
4.41
3.93
31
3.22
2.88
31
mean
std. dev.
N
1.75
1.23
27
sig,
P<0.001
1.76
2.05
27
sig,
P<0.001
mean
std. dev.
N
0.22
0.17
31
0.19
0.11
31
mean
std. dev.
N
0.19
0.36
27
ns
0.10
0.08
27
ns
Canal
2.39
1.40
23
South Bay
South Bay
Eastern
Corner
0.25*
0.35
13
0.49*
1.38
13
0.04
0.04
24
0.18*
0.21
13
2.60
1.71
24
0.14
0.15
24
0.12*
0.06
13
0.171
0.137
23
0.31*
0.33
13
0.21*
0.20
13
0.07
0.04
27
The flow rates and nutrient concentrations can be combined to make an estimate of the
annual input of dissolved inorganic nitrogen to the Bay from the Ponds. A frequency
distribution was made of the hourly tide heights in the Bay over a one year period. This
frequency distribution was then analyzed to determine what proportion of the time the tide
9
height in the Bay would be below the level which would cause outflow from the Ponds through
the Canal or culvert system EK 2 (EK 1 culverts were ignored because of their very low flow
rates). This proportion of the year’s time was then multiplied times the discharge rates from
the Canal and ‘Ekahi Pond (Figures 1 and 2), and this product was in turn multiplied times the
average concentration of dissolved inorganic nitrogen. The results of this calculation are shown
at the bottom of Table 2. The results show that the volume of discharge per year is greater
than that of figures for any of the streams, and that the discharge of N from the ponds,
particularly through the Canal, is contributing substantially to the input of nitrogen to the South
Bay. The discharge from the Ponds can be compared to the discharges from the 4 major
streams which enter the South Bay: Kawa, Kāne‘ohe (including Kamoalii), and Kea‘ahala
streams. The discharge from the Ponds (culverts plus Canal) is equivalent to the discharge from
any of these streams. The discharges from the streams differ from the discharge from the
Ponds in that stream waters are much richer in NO3.
Table 2: Comparison of the flow rates, nutrient concentrations, and contributions of dissolved inorganic
nitrogen to the waters of Kāne‘ohe Bay by streams and the Nu‘upia Canal as reported in this and
previous studies.
System
Kaneohe Str
Kaneohe Str
Kaneohe Str
Kaneohe Str
Flow rate Flow rate Flow rate Concentrations
per year per day
NO3
NH4
DON
TDN
m3/sec
106m3
0.169
4.500
0.189
5.960
Keaahala Str
Keaahala Str
Keaahala Str
Kawa Str
Kawa Str
Kawa Str
Kawa Str
Kawa Str
14.602
41.202
16.3296
44.604
μM
μM
μM
μM
15.00
2.60
12.00
31.00
6.00
1.90
7.30
17.00
10.79
17.19
3.38
1.53
Source
67.50
Hoover, 2002
Cox et al 1973, pg 15
Yim and Dugan 1975
Cox et al 1973, pg 381
11.70
Hoover, 2002
Cox et al 1973, pg 15
Cox et al 1973, pg 381
12.870
3.780
0.092
0.092
SE Bay pre
Canal
EK2
EK1
EK 1 and EK2
103m3/d
Annual N flux k moles/yr
NO3
NH4
DIN
1.500
0.150
0.002
2.914
2.914
7.983
7.983
3.780
5.103
6.048
5.110
14.000
23.587
2.359
0.038
64.622
6.462
0.103
28.200
2.40
0.49
0.70
2.60
1.76
1.75
31.44
50.09
22.24
20.46
24.13
56.61
1.16
0.03
9.85
4.46
61.33
4.15
0.07
AECOS and DOH KawaStreamNutrientData.xls
AECOS and DOH KawaStreamNutrientData.xls
Cox et al 1973, pg 15
Cox et al 1973, pg 380
Cox et al 1973, pg 381
255.50
Smith et al 1981
117.94
5.31
0.09
This study
This study
This study
Aecos 1985
Drogues released near the outlets from the Ponds moved SW across the reef flat of the SE
end of the Bay when tide levels were greater than the height of the reef, approximately 95 % of
the time. Waters of the Ponds are slightly more saline than the Bay waters but also slightly
warmer, so it is assumed they remain at or near the surface of the Bay waters. The speed of
drogue movement was approximately 12 cm sec-1.
10
26.3
Surface drogues
Shore
Reef margin
26.2
26
25.9
Latitude
26.1
AM
25.8
25.7
25.6
46.2
46
45.8
45.6
45.4
Figure 3: Paths of drogues released in the waters just off the Canal mouth and the ‘Ekahi pond culverts.
Blue and green lines represent the edge of the SE reef flat and the coastline/Pond margin. Aerial
photograph shown for comparison with schematic view.
Discussion
The waters flowing out of the Nu‘upia ponds through the canal and the two sets of culvert
are substantially richer in dissolved inorganic nitrogen than are the waters of the Bay. This is
significant because fixed nitrogen is the limiting nutrient for most algal species in the Bay,
including the invasive macroalgae, and these forms of fixed nitrogen are readily taken up from
the waters by these algae. The estimate of the yearly flux of these nutrients out of the ponds
gives a figure which is equivalent to the estimated input of dissolved inorganic nitrogen by any
of the 3 major streams flowing into the South Bay. This comparison is interesting because
previous considerations of the nutrient budget of the Bay have evidently not considered the
contribution of the outflow from the Ponds (Smith et al. 1981, Freeman 1993).
A previous estimate was made of the volume of water discharged from the Ponds (AECOS
1985). The study only estimated the discharge from ‘Ekahi Pond and produced an estimate of
discharge through the culverts which is higher than the one presented here (Tab. 2), possibly
because the study estimated the flow rates based on: 1) differences in water level in Ponds and
in the Bay and 2) how the characteristics of the culvert pipes would have influenced fluid flow.
The earlier study of flow did not estimate the discharge from the Canal even though at the time
the Canal and the Ponds were connected. As of 1989 the canal and ponds were connected by a
break or breaks in the Canal wall bordering Halekou Pond (AECOS 1989). Breaks in this Canal
wall are evident in Google Earth images dating back to 2000, as are breaks connecting Halekou
and ‘Elua Ponds.
This project did not examine the reasons for these elevated inorganic nitrogen values in the
Pond waters; presumably this results from a combination of causes. There are occasional spills
from the sewage treatment plant on land adjacent to the Ponds. These spills make their way
into the SW corner of the Pond system and most directly into Nu‘upia ‘Elua close to where it
communicates with Nu‘upia ‘Ekahi. Two spills occurred from the plant during the period of this
study: one on June 5, 2011 and one on July 31, 2011. Secondly, there is runoff from the
11
surrounding watershed into the Ponds which could carry nutrients into the Ponds (AECOS
1989). Thirdly, the pond sediments are probably rich in nutrients due to the decomposition of
organic matter including material from the emergent vegetation. In 1995 mangroves were
destroyed in order to create more open shallow-water area at the margins of the Ponds to
encourage nesting by native wading bird species. Decomposition of this material could also be
adding to the dissolved nutrient levels in Pond water. There was no immediate effect on
nutrient concentrations in a comparison of water samples from two stations taken just prior to
and just after mangrove removal (Cox and Jokiel, 1997). The Cox and Jokiel (1997) study
examined nutrient levels at 16 stations distributed around the entire Pond system and shows
little in the way of patterns of nutrient concentrations which might reveal sources, except that
‘Ekahi Pond tended to have higher NH4 levels than the other ponds. More detailed studies,
including more frequent sampling, could now be done to localize high levels of nutrients
particularly focusing on segments of the Canal and points where storm water or overflows
enter the Ponds.
Water exiting the Ponds via the canal and the culverts is moved south west by the action of
the trade winds. Our drogues were approximately 30 cm tall and so presumably represented
the movement of the upper layers of the water column. Although the water exiting the Ponds
would be diluted by Bay water before it reaches the SE fringing reef of the Bay, the waters
would have a somewhat enhanced N content relative to Bay water because Pond waters are
enriched in dissolved N relative to Bay waters. Bioassays could be performed to examine
whether algae on the SE fringing reef have enhanced growth rates or nutrient levels compared
to algae on other reefs not so directly exposed to watershed-derived dissolved nutrients.
12
References
AECOS. 1985. “Before”/”after” monitoring of water quality and hydrological patterns in
association with a channel dredging project at Nu‘upia Ponds Wildlife Management Area
(WMA). 106pp.
AECOS. 1989. Evaluation of predicted stormwater runoff changes on endangered waterbird
habitat Nu‘upia Ponds Wildlife Management Area, Marine Corps Air Station, Kaneohe
Bay, O‘ahu, Hawai‘i, Park Engineering. 88pp.
Cox, D. C., P. F. Fan, K. E. Chave, R. I . Clutter, K. R. Gundersen, N. C. Burbank Jr., L. S. Lau, J. R.
Davidson and others. 1973. Estuarine Pollution in the State of Hawaii. Vol. 2: Kaneohe
Bay Study. Technical Rept. # 31, Water Resources Research Center, Univ of Hawai‘i.
444pp.
Cox E. F. and P. L. Jokiel. 1997. Environmental study of Nu‘upia Ponds Wildlife Management
Area, Marine Corps Base Hawai‘i, Kāne‘ohe Bay. Final report submitted to
Environmental Compliance and Protection Dept., Environmental Affairs Div, Marine
Corps Base Hawaii. 98pp.
Cox, E.F., M. Ribes, R.A. Kinzie III. 2006. Temporal and spatial scaling of planktonic responses to
nutrient inputs into a subtropical embayment. Mar Ecol Prog Ser 324:19-35.
De Carlo, E. H., D. J. Hoover, C. W. Young, R. S. Hoover and F. T. Mackenzie. 2007. Impact of
storm runoff from tropical watersheds on coastal water quality and productivity. App
Geochem 22:1777-1797.
Freeman, W. 1993. Revised total maximum daily load estimates for six water quality limited
segments Island of O‘ahu, Hawai‘i. Environmental Planning Office, Hawai‘i State Dept of
Health, Honolulu, Hawai‘i. 134pp.
Hoover, D. J. 2002. Fluvial nitrogen and phosphorus in Hawaii: Storm runoff, land use, and
impacts on coastal waters. PhD Diss Univ of Hawai‘i.
Hunter, C. L. and C. W. Evans. 1995. Coral reefs in Kaneohe Bay, Hawaii: two centuries of
western influence and two decades of data. Bull Mar Sci 57:501-515.
Larned S. T. and J. Stimson. 1996. Nitrogen-limited growth in the coral reef chlorophyte
Dictyosphaeria cavernosa, and the effect of exposure to sediment-derived nitrogen on
growth Mar Ecol Prog Ser 145:95-108.
Laws, E. A. and C. B. Allen. 1996. Water quality in a subtropical embayment more than a
decade after diversion of sewage discharges. Pac Sci 50: 194-210.
13
Ringuet, S. and F. T. Mackenzie. 2005. Controls on nutrient and phytoplankton dynamics
during normal flow and storm runoff conditions, Southern Kaneohe Bay, Hawaii.
Estuaries 28327-337.
Smith, S. V., W. J. Kimmerer, E. A. Laws, R. E. Brock and T.W. Walsh. 1981. Kaneohe Bay
sewage diversion experiment: Perspectives on ecosystem responses to nutritional
perturbation. Pac Sci 35:279-395.
Te, F. T. 2001 Responses of Hawaiian scleractinian coral to different levels of terrestrial and
carbonate sediment. PhD Diss, Univ of Hawai‘i. 264pp.
Yim and Dugan 1975 Water quality monitoring Kaneohe Bay and selected watersheds: July to
December 1975. Water Res. Research Ctr., Univ. of Hawaii, Technical Rept. #93.
14