Coral Reef Restoration Handbook - Chapter 2 pptx

25

2

A Thousand Cuts? An Assessment
of Small-Boat Grounding
Damage to Shallow Corals of the
Florida Keys

Steven J. Lutz

CONTENTS

2.1 Introduction 25
2.2 Materials and Methods 26
2.3 Results 29
2.3.1 Geographic Distribution 29
2.3.2 Reef Sites 30
2.3.3 Head/Cluster Size 31
2.3.4 Depth of Head/Clusters 32
2.3.5 Mooring Buoys 32
2.4 Discussion and Conclusions 32
2.4.1 Geographic Distribution 33
2.4.2 Reef Size 33
2.4.3 Head/Cluster Size 33
2.4.4 Depth of Head/Clusters 33
2.4.5 Mooring Buoys 34
2.4.6 Impacts to Individual Coral Heads 34
2.4.7 Trend in High User Pressure 34
2.4.8 Management Considerations 34

2.5 Conclusion 36
Acknowledgments 36
References 36

2.1 INTRODUCTION

For thousands of years coral reefs have survived natural impacts, such as storms, diseases, and
predation. What they cannot withstand is the combination of these natural impacts with severe or
repeated anthropogenic damage, such as overfishing, sedimentation, and excess nutrients. Reefs
around Jamaica and San Andres have been devastated by this combination,

1,2

and Florida reefs are
widely reported to decline.

3,4

Indeed, according to Wilkinson (1992),

5

South Florida’s reefs are so
“threatened” that they may disappear in 20 to 40 years.
Anthropogenic impacts to corals can be divided into direct and indirect effects.

6

Indirect
anthropogenic impacts throughout the Florida Keys, which include poor water quality and high

2073_C002.fm Page 25 Friday, April 7, 2006 4:36 PM
© 2006 by Taylor & Francis Group, LLC

26

Coral Reef Restoration Handbook

sedimentation rates, have received great attention from the scientific community.

4,7–11

However,
there is comparatively little information on direct anthropogenic damage, such as broken or over-
turned corals, on Florida coral reefs. Much of this research has been related to the damage and
rehabilitation of larger vessel groundings, which are highly visible and well documented.

12–14

In contrast, little or no information on direct physical damage to corals caused by smaller
vessels is available. Previous studies and reports have noted this form of damage,

12,15–20

also referred
to as “orphan groundings” by Florida Keys National Marine Sanctuary staff. However, the amount
of damage caused by small vessels that are able to leave grounding incidents under their own power
is unreported and may be vast; certainly, such incidents are much more numerous than large vessel
groundings. In the Florida Keys small-vessel grounding damage may be particularly widespread
because many of the reefs that attract visitors have shallow-water corals. Assessing the extent,

amount, and impact of this form of anthropogenic damage to coral is essential for reef management.
This report is the first estimate of the geographic distribution and severity of small-vessel
grounding damage on shallow-water massive corals of patch reefs throughout the Florida reef tract.
In this assay 315 shallow-water massive coral colonies from 49 reef sites within the Florida reef
tract were examined for signs of boat grounding damage.

2.2 MATERIALS AND METHODS

This study was conducted from August 1996 to January 1997 on 49 reef areas with high-profile shallow-
water coral heads or clusters of heads in the Florida Keys reef tract (Figure 2.1 and Figure 2.2). All
but one of the reef sites surveyed were patch reefs; the exception was Carysfort Reef, a bank-barrier
reef. Patch reefs occur throughout the Florida reef tract. They are particularly abundant in the waters
off northern Elliot Key and south Key Largo, which include over 5000 patch reefs.

21

Patch reefs
typically occur in water 2 to 9 m deep and vary from 30 to 700 m in diameter.

22

In the Florida
Keys, the framework builder coral species of patch reefs include

Siderastrea siderea

,

Diploria
strigosa

,

D. labyrinthiformis

,

Colpophyllia natans

,

Montastraea annularis

, and

M. faveolata.

These
corals have been termed boulder or massive corals.

23



Montastraea annularis

(

senso lato

) is partic-
ularly important as it has been described as a “keystone” species

24

and can exhibit lateral growth
as it approaches sea level. This massive coral can be found growing in individual colonies, or heads,
and in groups of amalgamated colonies, or clusters, growing together. They can grow to be up to
100 m

2

in area and have up to 5 m of relief.

25

Shallow-water massive coral heads and clusters of
shallow massive coral heads are termed head/clusters for the purposes of this study. The geographic
location of each reef site was recorded with a hand-held global positioning system.
The exact depth and diameter of each coral head/cluster found within 2 m of the surface was
recorded for each reef site. The survey depth of 2 m was chosen to accommodate for tidal range
(~1.5 m) and the maximum depth of typical hulls and/or propellers for small vessels (~1 m). The
Northern Florida Keys tidal range was determined by inspection of tide tables.

26,27

To account for
tidal variation, all

in situ

depth measurements were standardized to depth below spring mean low
water tide level. Standardized depths ranged from 0.1 to 1.0 m. According to vessel registration
records, the majority of registered vessels in Miami-Dade and Monroe Counties are pleasure craft
from 16 to 26 ft in length. In the two counties, 36,312 such vessels were registered in 1994,
accounting for 56% of all registered vessels.

28

Miami-Dade and Monroe Counties are the closest
counties to the northern Florida reef tract. All of the corals in this survey were potentially susceptible
to small-vessel grounding damage.
Reefs surveyed contained from one to 28 shallow-water head/clusters with the majority, 75%,
containing from one to five head/clusters. In total, 315 coral head/clusters were measured.
Head/clusters ranged in size from less than 1 m (a singular head) to 18 m in diameter (a large
cluster of amalgamated heads). The majority, 79%, were less than 5 m in diameter. Tidal range
corrected depth of the top surfaces of head/clusters ranged from 25 cm to 1 m in depth; 39%
from 0 to 0.25 m deep, 51% from 0.25 to 0.75 m deep, and 10% from 0.75 to 1 m deep.

2073_C002.fm Page 26 Friday, April 7, 2006 4:36 PM
© 2006 by Taylor & Francis Group, LLC

A Thousand Cuts?

27

Of the 315 shallow-water head/clusters surveyed, 312 were

Montastraea

spp. and three were

S. siderea. Montastraea

spp. were identified according to the classifications of Weil and Knowlton
(1994).

29



Montastraea annularis

and

M. faveolata

were the only

Montastraea

spp. recorded in the
survey. These two coral species commonly co-occur.

30

FIGURE 2.1

Approximate locations of reef sites surveyed (North Florida reef tract).
South

Florida
Lower
Keys
Middle
Keys
Upper
Keys
N
Caesar
Creek
Bache Shoal patch reef
Patch reef east of
channel marker 11
Patch reef east of
channel marker 13
Patch reef east of
channel marker 19
Patch reefs southeast
of channel marker 17
Patch reefs east of
channel marker 21
East Basin Hill Shoals patch reefs
Carysfort reef
Basin Hill Shoals patch reefs
North Sound
South Sound
Cannon patch reef
Mosquito Bank patch reefs
Dry Rocks patch reef
80 20' 80 10'

25 10'
25 20'
Land
Reef area with shallow head/cluster
corals, undamaged
Reef area with shallow head/cluster
corals, damaged
Broad Creek
Haw
k Ch
ann
el
(approx. route)
Ell
iot Key
Key Largo

2073_C002.fm Page 27 Friday, April 7, 2006 4:36 PM
© 2006 by Taylor & Francis Group, LLC

28

Coral Reef Restoration Handbook

Although

Acropora palmata

is commonly found growing close to the surface, this coral was not
included in the survey. This coral species is particularly vulnerable to natural fragmentation during

storms, which renders it difficult to distinguish between natural and anthropogenic damage.

31,32

For underwater observations of direct physical damage a meter rule marked in 2- and 10-cm
increments was used. Damage was recorded in square



centimeters and as the extent of surface area
destroyed. Two forms of physical damage were identified, collision damage and scarring damage.
Collision damage occurs when a coral is crushed and split by a vessel’s hull into multiple fragments.
Hull paint is often driven into the coral skeleton (Figure 2.3A and Figure 2.3G). Scarring damage,
from boat propellers, tears off live coral, exposing the skeleton. In propeller scarring, typical scarlike
striations are seen (Figure 2.3B, Figure 2.3C, Figure 2.3D, Figure 2.3E, Figure 2.3F, and Figure 2.3I),
and large fragments of coral can be chipped off (Figure 2.3E, Figure 2.3G, Figure 2.3H, and Figure 2.3I).
Any damage whose source was not readily identifiable, for example when the surfaces were
completely overgrown by turf algae and the corallites were not exposed or identifiable, was not
included in the survey.
Statistical analysis was performed with the

t

-test and analysis of variance (ANOVA) where
applicable.

FIGURE 2.2

Approximate locations of reef sites surveyed (Middle and South Florida reef tract).
South

Florida
Upper
Keys
25 58'
80 34'
81 24'
24 38'
24 36'
Munson Heads patch reefs
Newfound Harbor Keys
81 28'
Loggerhead Key
Monkey Head patch reef
Hawk Channel (approx. route)
Approach to Newfound
Harbor Channel
Hawk Channel to
the southeast
e Rocks patch reefs
Lower
Keys
Land
Reef area with shallow head/
cluster corals, undamaged
Reef area with shallow head/
cluster corals, damaged
Middle
Keys
B
B

A
N
A
Plantation Key
New
Snake Creek

2073_C002.fm Page 28 Friday, April 7, 2006 4:36 PM
© 2006 by Taylor & Francis Group, LLC

A Thousand Cuts?

29

2.3 RESULTS
2.3.1 G

EOGRAPHIC

D

ISTRIBUTION

The results indicate that boat damage was widespread. Most (57.1%) of the shallow-water reef
sites surveyed showed signs of damage. Of the 315 coral head/clusters found on those reefs, 79
(25%) had been damaged. The total estimated area of destroyed coral found was 37,675 cm

2

. The

area of damage to individual head/clusters ranged from 25 to 5800 cm

2

. Most damage found on

(A) (B)
(C)
(D)
(E)
(F)

FIGURE 2.3

Damage to various head/clusters. A. Patch reef southeast of channel marker 17, Biscayne
National Park (BNP). Arrows indicate boat hull paint embedded in coral. B. Patch reef east of channel marker
21, BNP. Arrow indicates small propeller scar. C. Mosquito Bank patch reef, John Pennekamp Coral Reef
State Park (JPCRSP). D. East Basin Hill Shoals patch reef, Florida Keys National Marine Sanctuary (FKNMS).
E. Basin Hill Shoals patch reef, JPCRSP. F. Patch reef area southeast of channel marker 17, BNP. G. Bache
Shoal patch reef, BNP. Arrows indicate crushed coral and boat hull paint. H. Munson Heads patch reef,
FKNMS. I. East Basin Hill Shoals patch reef, FKNMS.

2073_C002.fm Page 29 Friday, April 7, 2006 4:36 PM
© 2006 by Taylor & Francis Group, LLC

30

Coral Reef Restoration Handbook

individual head/clusters was under 250 cm

2

(illustrated in Table 2.1). Two reefs, Bache Shoal and
Mosquito Bank (see Figure 2.1), had much more severe extent of damage than all other reef sites
(3366 +/– 1570 cm

2

(

n

= 6) on Bache Shoal and Mosquito Bank compared to 775 +/– 109 cm

2

(

n

= 22) on all other reef sites,

P

= 0.0017). These two reefs accounted for 60.2% of all damage
found (20,200 cm

2

). However the occurrence of damage incidents to head/clusters was not statis-
tically significantly higher than at other reef sites (48.5 +/– 12.3% of head/clusters damaged on
Bache Shoal and Mosquito Bank compared to 28.9 +/– 5.98% damaged on all other reef sites).

2.3.2 R

EEF

S

ITES

Reef sites surveyed contained from one to 28 shallow-water massive coral head/clusters. The total
amount of damage found on head/clusters per each reef site ranged from 25 to 10,925 cm

2

coral
destroyed.
For a comparative assessment of reef size damage, reef sites were divided into three size
categories: small (zero to five head/clusters per reef); medium (six to 15 head/clusters per reef);

(G)
(H)
(I)

FIGURE 2.3

(Continued.)

TABLE 2.1
Percent of Damaged Head/Clusters by Area of Coral Destroyed

Area of Coral Destroyed (cm

2

)

≤

250



251 to 500 501 to 1500 1501 to 3000

>

3000

Percent of damaged
head/clusters
49.3 (

n



=

39) 24 (

n



=

19) 20.3 (

n



=

16) 5 (

n



=

4) 1.3 (

n

=

1)

2073_C002.fm Page 30 Friday, April 7, 2006 4:36 PM
© 2006 by Taylor & Francis Group, LLC

A Thousand Cuts?

31

and large (>15 head/clusters per reef) (illustrated by Table 2.2). Damage among these reef size
classes was distributed in the following proportions: 17 of the 36 (47.2%) small reefs, four of the
six (66.6%) medium reefs, and seven of the seven (100%) large reefs had signs of damage.
A significant correlation was found between the number of shallow-water head/clusters per
reef site and the amount of damage (mean total area in square centimeters per reef site): large reefs
= 2557 +/– 1414 cm

2

(

n

= 7); medium reefs = 700 +/– 375 cm

2

(

n

= 6); small reefs = 421 +/–
117 cm

2

(

n

= 36),

P

= 0.0055. A significant correlation was also found between the number of
shallow-water head/clusters per reef site and the mean number of damaged head/clusters per reef
site: (large reefs = 5.0 +/– 0.976 (

n

= 7); medium reefs = 2.5 +/– 1.147 (

n

= 6); small reefs = 0.806
+/– 0.19 (

n

= 36),

P

= 0.0001 (illustrated by Table 2.2).
However, the number of shallow-water head/clusters per reef site did not appear to influence
mean damage incidence or wound size: large reefs = 431 +/– 158 cm

2

(

n

= 17); medium reefs =
218 +/– 68 cm

2

(

n

= 4); small reefs = 528 +/– 125 cm

2

(

n

= 7) (illustrated in Table 2.2).

2.3.3 H

EAD

/C

LUSTER

S

IZE

In order to determine whether head/cluster size influenced damage incidence, the 315 shallow-
water massive coral head/clusters were divided into three size categories: small (< 5 m diameter);
medium (5 to 10 m diameter); and large (>10 m diameter) (illustrated in Table 2.3). No connection
was found concerning damage incidence; 54 of the 240 (22.5%) small head/clusters, 17 of the 47
(36.1%) medium head/clusters, and eight of the 28 (28.5%) large head/clusters were damaged.

TABLE 2.2
Reef Size and Damage

Reef Size Class (Number of Head/Clusters)
Small (1 to 5) Medium (6 to 15) Large (Over 15)

Number of head/clusters
per reef size class

3667
Percent of reefs damaged 42.2 (

n



=

17) 66.5 (

n



=

4) 100 (

n



=

7)
Mean area (cm

2

) of
damage
421

+

/

−

117 (

n



=

36) 700 +/

−

375 (

n



=

6) 2557 +/

−

1414 (

n



=

7)
Mean number of
damaged head/clusters
0.806 +/

−

0.19 (

n



=

36) 2.5 +/

−

1.147 (

n



=

6) 5.0 +/

−

0.976 (

n



= 7)
TABLE 2.3
Head/Cluster Size and Damage
Head/Cluster Size
Small (<5 m
Diameter)
Medium (5 to 10 m
Diameter)
Large (>10 m
Diameter)
Number of head/clusters per

head/cluster size class
240 47 28
Percent of damaged
head/clusters
22.5 (n = 54) 36.1 (n = 17) 28.5 (n = 8)
Mean area (cm
2
) of damage
per head/cluster size class
77 +/− 15 (n = 240) 282 +/− 131 (n = 47) 194 +/− 109 (n = 28)
2073_C002.fm Page 31 Friday, April 7, 2006 4:36 PM
© 2006 by Taylor & Francis Group, LLC
32 Coral Reef Restoration Handbook
However, it was found that head/cluster diameter did influence the extent of damage (mean area
in square centimeters per head/cluster size class). Medium and large head/clusters had more damage
than did those in the small size class: small head/clusters = 77 +/– 15 cm
2
(n = 240); medium
head/clusters = 282 +/– 131 cm
2
(n = 47); large head/clusters = 194

+/– 109 cm
2
(n = 28), P = 0.0087.
2.3.4 DEPTH OF HEAD/CLUSTERS
The depth below mean low-water level of the top surfaces of the shallow-water head/clusters ranged
from 0 to 1.0 m. In order to investigate the effect of depth on damage, the head/clusters were divided
into three depth categories: 0 to 0.3, 0.4 to 0.6, and 0.7 to 1.0 m depth (illustrated in Table 2.4).
Damage incidence among the depth classes was distributed in the following proportions: 37 of the

123 (30%) 0- to 0.3-m deep head/clusters had signs of damage, as did 37 of the 161 (22.9%) 0.4-
to 0.6-m deep head/clusters and five of the 31 (16.1%) 0.7- to 1.0-m deep head/clusters. Damage
extent (total square

centimeters of coral damaged per head/cluster) among the depth classes was
distributed in the following proportions: 15,200 cm
2
of the 0- to 0.3-m deep head/clusters coral was
destroyed, 21,775 cm
2
of the 0.4- to 0.7-m deep head/clusters coral was destroyed, and 700 cm
2
of
the 0.7- to 1.0-m deep head/clusters coral was destroyed. The three depth categories do not signif-
icantly differ from each other in either damage incidence or extent. Neither, when damage occurs,
does the depth of the top surfaces of shallow-water head/clusters affect the area of coral destroyed
(mean area

in square centimeters per damaged head/clusters) (0 to 0.3 m depth = 578 +/– 171 cm
2
(n = 37); 0.4 to 0.6 m depth = 410 +/– 76 cm
2
(n = 37); 0.7 to 1 m depth = 140 +/– 67 cm
2
(n = 5).
2.3.5 MOORING BUOYS
Of the seven reef sites with mooring buoys that were surveyed, all but one had signs of damage.
Of the 42 reefs without mooring buoys surveyed, 22 had signs of damage. However upon statistical
evaluation, it was found that whether or not a reef had a mooring buoy did not affect the frequency
of damage incidence (37.3 +/– 16.5% for reef sites with buoys [n = 7] compared to 30.3 +/– 5.9%

for reef sites without buoys [n = 42]). Similarly, the extent of damage (mean area

in square
centimeters) found on reef sites is not affected by the presence or absence of mooring buoys
(1415 +/– 485 cm
2
[n = 22] on reefs without buoys compared to 1021 +/– 485 cm
2
on reef sites
with buoys [n = 6]). The presence or absence of mooring buoys on a reef did not significantly
affect the degree of damage caused by small-boat groundings.
2.4 DISCUSSION AND CONCLUSIONS
Most damage found on individual head/clusters was under 250 cm
2
. Although this category of damage
appears widespread throughout the study range, it does not suggest that it is a cause of any specific
decline in the health of corals throughout the Florida Keys reef tract. Additionally, the Florida Keys
TABLE 2.4
Depth of Head/Clusters and Damage
Head/Cluster Depth
0 to 0.3 m 0.4 to 0.6 m 0.7 to 1.0 m
Number of head/clusters 123 161 31
Percent damaged head/clusters 30 (n = 37) 22.9 (n = 37) 16.1 (n = 5)
Total area (cm
2
) of damage per
head/cluster
15,200 21,775 700
2073_C002.fm Page 32 Friday, April 7, 2006 4:36 PM
© 2006 by Taylor & Francis Group, LLC

A Thousand Cuts? 33
reef tract is a vast natural structure, most of which remains submerged out of smaller-vessel impact
range during tidal fluctuations. While the direct damage from small-boat contact does not pose a
serious threat to its overall survival, the accumulated damage can degrade and destroy the structure
of localized areas of shallow-water corals and coral clusters, demonstrating this impact’s importance
to the health of localized head/clusters and contributing to the stresses these corals already experience.
2.4.1 GEOGRAPHIC DISTRIBUTION
The total amount of damage found at Bache Shoal and Mosqutio Bank was substantial, 60.2%
of all damage found. Indeed, these reefs show impact levels significantly higher than those of
all other reefs. Bache Shoal is one of the closest shallow reefs with mooring buoys to metro-
politan Miami and is directly adjacent to a major boating channel, Hawk Channel (see Figure
2.1). To prevent vessel impacts, it is marked by a triangular reef warning tower and channel
marker at its north tip. It is significant to note that all shallow head/clusters surveyed at Bache
Shoal were damaged, suggesting that its level of use or boat traffic (and related impacts) exceeds
the safety methods used. Mosquito Bank, located adjacent to Hawk Channel and directly in
the line of boat traffic coming from slips on Key Largo and South Sound, also has a high
percentage (42.6%) of head/clusters damaged, indicating a high level of use or traffic and the
need for additional protection. Results also suggest that these reef areas may be experiencing
collisions by vessels that are larger and/or going much faster than on other reef sites. Mosquito
Bank’s high percentage of damage supports the Florida Department of Environmental Protec-
tion’s findings.
33,34
Farther south, navigation channels and boater access may also play important
roles in boat grounding damage, as The Rocks and Munson Heads are both adjacent to boating
routes (see Figure 2.2).
2.4.2 REEF SIZE
It appeared that reefs with five or more shallow-water head/clusters were more susceptible to small-
boating damage than were reefs with fewer than five shallow-water head/clusters. The more shallow-
water head/clusters that a reef has, the more damage incidents or wounds, but the mean wound
size remained the same, regardless of reef size. Larger reefs may receive more damage because

the likelihood of collision with a larger reef area is greater, even though smaller reefs are more
numerous. However, smaller reefs may also not be as attractive to small-boat traffic from tourists
because they have less relief, smaller associated fish populations, and a smaller amount of live coral.
2.4.3 HEAD/CLUSTER SIZE
It appeared that the larger, in diameter, a shallow-water head/cluster, the more damage, but the
frequency of damage remains the same, regardless of diameter. It is possible that small-vessel
impact damage is infrequent overall and occurs at random. However, when such damage occurs,
the larger in diameter a head/cluster, the greater the chance that a single damage incident will result
in substantial damage.
2.4.4 DEPTH OF HEAD/CLUSTERS
It was interesting to find that within the 1-m depth range from spring low tide, the depth of the
top surfaces of shallow-water head/clusters did not significantly influence either the degree or
extent of damage caused by small-boat groundings. Therefore, all corals within a 1-m depth
range from spring low tide are susceptible to small-vessel grounding damage. If the sample
depth range of this survey had been extended to 2 or 3 m, frequency and extent of damage
might have significantly correlated with depth; this, however, would have greatly lengthened
survey time.
2073_C002.fm Page 33 Friday, April 7, 2006 4:36 PM
© 2006 by Taylor & Francis Group, LLC
34 Coral Reef Restoration Handbook
2.4.5 MOORING BUOYS
One would expect to find higher levels of damage to shallow-water massive corals at reef sites with
mooring buoys since mooring buoys tend to attract more recreational boaters. However, the presence
or absence of mooring buoys on a reef did not significantly alter the frequency or extent of damage
caused by small-boat groundings. More recreational boaters may be drawn to reefs with mooring
buoys, but they appear to avoid any significant additional damage to shallow-water massive corals.
2.4.6 IMPACTS TO INDIVIDUAL CORAL HEADS
It might be expected that small-vessel groundings are an important cause of damage on localized
cluster-heads. Because boating damage tends to occur on the top surfaces of coral colonies, their
detrimental effects may be more substantial than those of other types of lesions. Damage caused by

storm rubble, in contrast, tends to occur more often on the sides of large colonies, rather than the tops.
Large lesions may not completely heal, although partial regeneration may occur at the edges.
35,36
It has
been found that within a week of a scarring event, filamentous algae colonize exposed skeleton and
inhibit coral regeneration. Turf algae or other reef organisms may be well established by the time the
healing margin of live coral reaches them. The encrustation of some organisms (e.g., boring sponges,
encrusting zoanthids) can lead to further bioerosion of the colony. Meesters (1995),
36
in a study
regarding damage and regeneration on scleractinian corals, showed that many lesions on the top surfaces
of bleached coral colonies enlarged to numerous times their initial size, occasionally resulting in the
death of the entire colony. Indeed, it appears that M. annularis may be very sensitive to bleaching.
36–38
Herbivorous fish pecking at the edge of a scar can consume turf algae and coral at the same time.
39
In
addition, coral scarring may affect the total health of the colony by forcing the coral to reallocate
resources to regeneration, and away from growth, reproduction, and combating disease.
Additionally, the cumulative effect of this form of damage to individual coral heads may have
negative tourism consequences. As impacts are to the shallowest and most accessible area of reefs,
they are easily within snorkeling range. Figure 2.3 clearly illustrates the diminished aesthetic value
of damaged coral heads.
2.4.7 TREND IN HIGH USER PRESSURE
The increasing trend of recreational use of South Florida marine habitat is evidenced by the 40.8%
increase in registered vessels in 10 years in Miami-Dade and Monroe Counties (from 62,274 in
1993 to 87,699 in 2003).
40,41
Indeed, it appears almost certain that continued high user pressure on
the most frequented reefs will, in a short time, degrade the aesthetic and recreational qualities of

the reefs. Additionally, the continued high and relentless incidence of damage to these colonies
will result in loss of the larger and older massive coral colonies. For these reasons it is imperative
that management deal with the small-boat problem as a priority.
2.4.8 MANAGEMENT CONSIDERATIONS
This study indicates that the cumulative effect of small-vessel groundings presents a serious threat
to localized coral eco-health and contributes significantly to other reef stresses. Marine parks and
management in the Florida Keys are charged with the protection of the natural resources, especially
coral reefs, under their jurisdictions. Table 2.5 illustrates coral damage on shallow water reef sites
by management authority for reefs surveyed. A comprehensive management plan is needed in order
to reduce the number of small-vessel groundings.
Management’s options for minimizing this type of anthropogenic damage would vary according
to available manpower and funds. In order to present a scientifically based management plan, the
author suggests that, first, localized shallow-water reef areas with high levels of user impact must be
identified. For “real time” observations, this type of survey should be carried out on an annual basis,
2073_C002.fm Page 34 Friday, April 7, 2006 4:36 PM
© 2006 by Taylor & Francis Group, LLC
A Thousand Cuts? 35
to gauge the direction of user pressure and to determine the effects of preservation and restoration
actions. The particular criteria for identifying such reefs should include an estimate of the percentage
of impacted shallow-water coral colonies. Special attention should be placed on reefs with over 15
shallow-water head/clusters, reefs with head/clusters over 5 m in diameter, and reefs close to navi-
gation channels and popular marinas. These reefs are especially prone to this type of impact.
Severity of damage incidence can be estimated from measurements of the area of coral destroyed,
as laid out in this chapter. Reefs with a high percentage of shallow-water corals damaged or colonies
with severe damage should be designated for immediate prevention and restoration action.
As a result of such surveys, the management options for damage prevention would depend
upon the severity of impact and could include the following:
1. The placement of additional “shallow reef” markers or other navigational beacons high-
lighting shallow corals prone to this type of impact
2. The targeted placement of additional mooring buoys (There are currently approximately

40 reef sites with mooring buoys throughout the Florida Keys.)
3. The establishment of small targeted preservation zones, which would restrict a certain
use (i.e., boating, diving, or fishing activities) and thereby lessen user pressure on a
particularly stressed and sensitive ecosystem
4. The establishment of critical zones, where all recreational and commercial access is
prohibited (Currently, approximately 6% of the Florida Keys National Marine Sanctuary
is set aside as fully protected zones known as ecological reserves, sanctuary preservation
areas, and special use areas.)
Education would also play an important part in reef preservation. Marinas and boat rental shops
close to damaged reefs could be targeted for educational materials, and boat pilot training programs
highlighting this type of problem could be planned. Advertising fines could help make boaters more
cautious while boating in shallow reef areas.
Individual coral head/cluster restoration options would depend upon the severity of impact and
could include the following:
1. No action taken: the wound size is so minimal that the coral’s natural healing process
will suffice to restore the damage, or restoration action may lead to further direct physical
damage to corals and surrounding benthos.
2. Stabilization and restructuring of unconsolidated coral fragments in a wound area, as
required, in order to mimic the look and function (biological and aesthetic) of the original
ecosystem.
The removal of bioeroding and competing organisms and/or the possible transplantation of
coral in an unnatural wound area, giving the natural healing process of damaged coral colonies a
“boost” (only feasible on the most severe of damage incidents).
TABLE 2.5
Reef Sites Surveyed and Management Authority
Management Authority
Percentage of Shallow
Reef Sites Surveyed
Percentage of Shallow Reef
Sites Surveyed with Damage

Biscayne National Park 22 54.5
John Pennekamp Coral Reef State Park 10 70
Florida Keys National Marine Sanctuary 17 52.9
2073_C002.fm Page 35 Friday, April 7, 2006 4:36 PM
© 2006 by Taylor & Francis Group, LLC
36 Coral Reef Restoration Handbook
2.5 CONCLUSION
In conclusion, this study shows that small-boat groundings on reef areas present a serious wide-
spread negative impact to localized coral eco-health, especially on larger reef areas and to massive
corals, and make a significant contribution to the stresses and pressures that corals already endure
throughout the Florida Keys reef tract (including bleaching, disease, pollution, large-vessel ground-
ings, high use, etc.).
It is imperative that small-vessel grounding damage be minimized. This distinct category of
anthropogenic damage is a major insufficiently recognized negative impact to highly visited coral
reef areas that must be dealt with in any scientifically based management plan.
ACKNOWLEDGMENTS
The author thanks the Florida Keys National Marine Sanctuary, Biscayne National Park, and John
Pennekamp Coral Reef State Park for their assistance, advice, and permission to conduct studies
under their jurisdictions and R.N. Ginsburg for project guidance, comments, and review. This project
was funded by the Filipacchi Hachette Foundation as part of the International Year of the Reef
Program (IYOR) and produced a masters thesis for the Division of Marine Affairs and Policy,
University of Miami, Rosenstiel School of Marine and Atmospheric Science (RSMAS).
REFERENCES
1. Hughes, T., et al. 1985. Mass mortality of the echinoid Diadema antilarum phlippi in Jamaica. Bull.
Mar. Sci. 36:377–384.
2. Hallock, P., et al. 1993. Coral reef decline. National Geographic Research & Exploration 9:385–387.
3. Porter, J.W., Meier, O.W. 1992. Quantification of loss and change in Florida reef coral populations.
Amer. Zool. 32:625–640.
4. La Pointe, B. 1994. Phosphorus inputs and eutrophication on the Florida reef tract. In: Ginsburg, R.N.
(ed.). Proc. Colloq. Global Aspects of Coral Reefs; Health, Hazards, and History, University of Miami,

Florida pp. 106–112.
5. Wilkinson, C. 1992. Coral reefs of the world are facing widespread devastation; can we prevent this
through sustainable management practices? In: Proc. 7th Int. Coral Reef Symp. Guam, Micronesia,
22–27 June, 1987. Mangilao, University of Guam Marine Lab., pp. 11–21.
6. Grigg, R., Dollar, S. 1990. Natural and anthropogenic disturbance on coral reefs. In: Goodall, D.W.
and Dubinsky, Z. (eds.). Coral Reefs; Ecosystems of the World. Elsevier, Amsterdam: pp. 439–452.
7. Glynn, P.W. 1989. Condition of coral reef cnidarians from the Northern Florida reef tract: pesticides,
heavy metals, and histopathological examination. Mar. Pol. Bull. 20:568–576.
8. Shinn, E., Miller, M. 1999, May. The Florida Keys: What is Happening to the Reef Tract and Why?
Poster presented at the South Florida Restoration Science Forum, Boca Raton, FL.
9. Shinn, E.A., Lidz, B.H., Hudson, J.H., Kindinger, J.L., Halley R.B. 1989. Reefs of Florida and the
Dry Tortugas: IGC Field Trip Guide T176. Washington, DC: American Geophysical Union, p. 53.
10. Cole, J. 1990. The state of our seas. Florida Keys Magazine 13(6):20–24.
11. Dustan, P., Halas, J.C. 1987. Changes to the reef-coral community of Carysfort Reef, Key Largo,
Florida: 1974 to 1982. Coral Reefs 6:91–106.
12. Causey, B.D. 1990. Biological assessments of damage to coral reefs following physical impacts
resulting from various sources, including boat and ship groundings. In: Jaap, W.C. (ed.). Proc. Am.
Acad. Underwater Sci., 10th Annual Diving Symposium, St. Petersburg, Florida, pp. 49–57.
13. Wheaton, J.L., Jaap, W.C., Kojis, B.L., Schmahl, G.P., Ballantine, D.L., McKenna, J.E. 1992. Trans-
planting organisms on a damaged reef at Pulaski Shoal, Ft. Jefferson National Monument, Dry
Tortugas, FL. (abstract). Bull. Mar. Sci. 54:1087–1088.
14. Miller, S.L., McFall, G.B., Hulbert, A.W. 1993. Guidelines and Recommendations for Coral Reef
Restoration in the Florida Keys National Marine Sanctuary, workshop report. NOAA, p. 38.
15. Dustan, P. 1977. Besieged reefs of the Florida Keys. Nat. His. 86:73–76.
2073_C002.fm Page 36 Friday, April 7, 2006 4:36 PM
© 2006 by Taylor & Francis Group, LLC

A Thousand Cuts?

37

16. Hudson, J.H., Goodwin, W.B. 2001. Assessment of vessel grounding injury to coral reef and seagrass
habitats in the Florida Keys National Marine Sanctuary, Florida: protocols and methods.

Bull. Mar.
Sci.

69:509–516.
17. Jaap, W.C. 1999. Coral Reefs. Presentation to the Florida Keys Carrying Capacity Study Ecosystems
Workshop, Marathon, FL, July 7–8, 1999.
18. Tilmant, J.T. 1987. Impacts of recreational activities on coral reefs. In: Salvat, B. (ed.).

Human Impacts
of Recreational Activities on Coral Reefs: Facts and Recommendations.

Antenne Museum E.P.H.E.
French Polynesia: pp. 195–209.
19. Tilmant, J.T., Schmale, G.P. 1981. A comparative analysis of coral damage on recreationally used
reefs within Biscayne National Park, Florida. In:

Proc. 4th Int. Coral Reef Symp.

Manila, 1:187–192.
20. Voss, G. 1983. An Environmental Assessment of the John Pennekamp Coral Reef State Park and the
Key Largo Coral Reef Marine Sanctuary (unpublished report).
21. Marszalek, D., Babashoff, G., Noel, M., Worley, P. 1977. Reef distribution in south Florida.

Proc.
3rd Int. Coral Reef Symp.,

Miami, FL. 2:233–230.
22. Jaap, W.C., Hallock, P. 1990. Coral reefs. In Myers, R.N. and Ewel, J.J. (ed.).

Ecosystems of Florida.

University of Central Florida Press: pp. 574–616.
23. Humann, P. 1993.

Reef Coral Identification.

Paramount Miller Graphics, Inc., Jacksonville, FL.
24. Hudson, H. 1981. Growth Rates in

M. annularis

: a record of environmental change in Key Largo
Coral Reef Marine Sanctuary, FL,

Bull. Mar. Sci.,

31:444–459.
25. Ginsburg, R.N., Shinn, E.A. 1993. Preferential distribution of reefs in the Florida reef tract: the past
is key to the present. In: Ginsburg, R.N. (ed.).

Global Aspects of Coral Reefs, Health Hazards and
History

. University of Miami, FL, pp. 21–26.
26. International Marine. 1996.

Tide Tables: High and Low Water Predictions, East Coast of North and
South America

. Camden, ME.
27. International Marine. 1997.

Tide Tables: High and Low Water Predictions, East Coast of North and
South America

. Camden, ME.
28. Boating Research Center. 1994.

Atlas of Boats, Florida, 1994.

University of Miami Rosenstiel School
of Marine and Atmospheric Science.
29. Weil, E., Knowlton, N., 1994. A multi-character analysis of the Caribbean coral

Montastraea annularis

and its two sibling species,

M. faveolata

and

M. franksi.

Bull. Mar. Sci.

55:151–175.
30. Knowlton, N., Mate, J.L., Guzman, H.M., Rowan, R., Jara, J. 1997. Direct evidence for reproductive
isolation among three species of the

Montastraea annularis

complex in Central America (Panama
and Honduras).

Mar. Bio.

127:705–711.
31. Fong, P., Lirman, D. 1995. Hurricanes cause population expansion of the branching coral

Acropora
palmata

(Scleractinia): wound healing and growth patterns of asexual recruits.

Mar. Ecol.

16:317–335.
32. Highsmith, R.C. 1982. Reproduction by fragmentation in corals.

Mar. Ecol.

(Prog. Ser.); vol. 7,
no. 2: pp. 207–266.

33. Deaton, A.S., Duquesnel, J.G. 1996. Marine Research and Resource Monitoring in John Pennekamp Coral
Reef State Park, 1995 Update Report, Update to Section I, Part C. Boat Grounding Assessments. Florida
Dept. of Environmental Protection, Division of Recreation and Parks, District 5 Administration, pp. 1–12.
34. Skinner, R.H., Deaton, A.S., Duquesenel, J.G. 1993. Marine Research and Resource Monitoring in
John Pennekamp Coral Reef State Park. Florida Dept. of Environmental Protection (eds.), Division
of Recreation and Parks, Region VII Administration: pp. 9–35.
35. Bak, R., Brouns, J., Heys, F. 1977. Regeneration and aspects of spatial competition in the scleractinian
corals

Agaricia agaricites

and

Montastrea annularis.

In:

Proc. 3rd Int. Coral Reef Symp.

Miami, FL,
pp. 143–149.
36. Meesters, E.H. 1995. Effects of coral bleaching on tissue regeneration potential and colony survival.
In Meesters, E.H.:

The Function of Damage and Regeneration in the Ecology of Reef-Building Corals
(Scleractinia).

Netherlands Institute for Sea Research (thesis publication): pp. 27–42.
37. Goreau, T.J., Macfarlane, A.H. 1990. Reduced growth rate of

Montastrea annularis

following the
1987–1988 coral bleaching event.

Coral Reefs

8:211–215.
38. Szmant, A.M., Gassman, N.J. 1990. The effects of prolonged bleaching on the tissue biomass and
reproduction of the reef coral

Montastraea annularis. Coral Reefs

8:217–224.
39. Glynn, P.W. 1990. Coral mortality and disturbances to coral reefs in the tropical eastern Pacific. In
Glynn, P.W. (ed.).

Global Ecological Consequences of the 1982–83 El Nino–Southern Oscillation.

2073_C002.fm Page 37 Wednesday, April 12, 2006 10:23 AM
© 2006 by Taylor & Francis Group, LLC
38 Coral Reef Restoration Handbook
40. Boating Research Center. 1994. Atlas of Boats, Dade County, Florida, 1993. University of Miami
Rosenstiel School of Marine and Atmospheric Science.
41. Florida Fish and Wildlife Conservation Commission. 2004. 2003 Boating Accident Statistical Report.
Retrieved October 2004. Available online at: http://www.floridaconservation.org/law/boating/2003
stats/2003StatBook1.pdf.
2073_C002.fm Page 38 Friday, April 7, 2006 4:36 PM
© 2006 by Taylor & Francis Group, LLC