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Spatial Abundance and Colour Morphotype Densities of the Rock-Boring Sea Urchin (Echinometra lucunter) at Two Different Habitats

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The rock-boring sea urchin Echinometra lucunter is a common echinoderm found throughout the intertidal zone along the northeastern coast of, Toco, Trinidad. Sea urchin abundance, size distribution, and colour morphotypes at two sites: Pequelle Bay (SB) and Grande L’Anse (GA) were quantified using 1 m2 quadrats, accessible during extreme low tides, and in two environments, notably low and high wave action. Percent coverage of cnidarian and macroalgae were estimated in each quadrat. Sea urchin densities were 9.9–17.8 urchins/m2 in high wave action, and 25.2–60.7 urchins/m2 in low wave action environments. Size (measured as maximum sea urchin diameter) are highest between 21 and 50 mm for both black and red colour morphotypes. Black colour morphs were significantly larger than red morphs (ANOVA, F2, 175 = 5.55, p < 0.05). Sea urchins at low energy environments were significantly larger than those found in high energy environments for all years (p < 0.05). Mean hard coral, soft coral, and macroalgae cover did not show any relationship with habitat type or urchin densities. Although sea urchin abundance and distribution were variable, larger urchins were more likely to be found in low wave action environments, and smaller urchins were mostly found in the open, and exposed to high wave action.
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1 23
Thalassas: An International Journal of
Marine Sciences
ISSN 0212-5919
Volume 36
Number 1
Thalassas (2020) 36:157-164
DOI 10.1007/s41208-019-00170-2
Spatial Abundance and Colour
Morphotype Densities of the Rock-Boring
Sea Urchin (Echinometra lucunter) at Two
Different Habitats
1 23
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Spatial Abundance and Colour Morphotype Densities
of the Rock-Boring Sea Urchin (Echinometra lucunter)
at Two Different Habitats
S. G. Belford
Received: 27 October 2018 /Revised: 28 February 2019
#Springer Nature Switzerland AG 2019
The rock-boring sea urchin Echinometra lucunter is a common echinoderm found throughout the intertidal zone
along the northeastern coast of, Toco, Trinidad. Sea urchin abundance, size distribution, and colour morphotypes
at two sites: Pequelle Bay (SB) and Grande LAnse (GA) were quantified using 1 m
quadrats, accessible during
extreme low tides, and in two environments, notably low and high wave action. Percent coverage of cnidarian
and macroalgae were estimated in each quadrat. Sea urchin densities were 9.917.8 urchins/m
in high wave
action, and 25.260.7 urchins/m
in low wave action environments. Size (measured as maximum sea urchin
diameter) are highest between 21 and 50 mm for both black and red colour morphotypes. Black colour morphs
were significantly larger than red morphs (ANOVA, F2, 175 = 5.55, p< 0.05). Sea urchins at low energy envi-
ronments were significantly larger than those found in high energy environments for all years (p< 0.05). Mean
hard coral, soft coral, and macroalgae cover did not show any relationship with habitat type or urchin densities.
Although sea urchin abundance and distribution were variable, larger urchins were more likely to be found in
low wave action environments, and smaller urchins were mostly found in the open, and exposed to high wave
Keywords Colour morphotypes .Wave action environments .Sea urchin .Echinometra lucunter .Fringing reef .Southern
The decline of coral reefs in the Caribbean due to
events, such as shifts in macroalgae dominance, local
point-sources of pollution, increasing sea surface tem-
peratures, overfishing, and other anthropogenic distur-
bances have been recorded over the years (Knowlton
2001;Pandolfietal.2003; Cameron and Brodeur
2007; Hughes et al. 2007; Burke et al. 2011;Perry
et al. 2015). In addition, coral bleaching events, and
disease outbreaks are becoming more frequent (Miller
et al. 2009;WeilandCróquer2009; Hoegh-Guldberg
et al. 2014; Heron et al. 2016), and recovery time be-
tween bouts is too short for full recovery (Hughes et al.
2018). Most notably, massive disease-induced sea urchin
Diadema antillarum (Philippi 1845) mortality has not
recovered after the outbreak in the early 1980s (Glynn
1984; Lessios et al. 1984).
Apart from past sea urchin mortality (Lessios et al.
1984;Hughes1994; Gardner et al. 2003), and continuing
trends in climate change, Caribbean reefs may change in a
dynamic way in the future (Raffaelli & Hawkins 1999;
Hernandez-Delgado and Suleiman-Ramos 2014). In partic-
ular, one valuable benthic organism that is important to
ecological reef processes are echinoids (Hughes 1994). In
fact, Echinometra lucunter (Linnaeus 1758) is one such
common echinoid found widely distributed throughout
the western Atlantic Ocean (Lewis and Storey 1984). In
addition, Echinometra virdis also shares common distribu-
tion in the Caribbean (Geyer & Lessios 2009), making
both species sympatric in this region.
Electronic supplementary material The online version of this article
( contains supplementary
material, which is available to authorized users.
*S. G. Belford
Division of Mathematics and Science, Martin Methodist College,
433 West Madison Street, Pulaski, TN 38478, USA
Thalassas: An International Journal of Marine Sciences (2020) 36:157164
/ Published online: 22 October 2019
Author's personal copy
Pawson (2007) stated that the Caribbean Sea alone
has a rich echinoderm diversity, with 433 echinoderm
species. Urchins have an integral impact on coral reef
communities, specifically related to their effects on al-
gae as herbivores, and as controllers of benthic commu-
nities (Carpenter 1986;Sala1997; Sanchez-Jerez et al.
2001; Rivera-Monroy et al. 2004; Cameron and Brodeur
2007; Miloslavich et al. 2010; Schultz 2010) and on
rock substrata with their bioeroding (Shiel and Foster
1986; Hughes 1994; Hendler et al. 1995). Although
much of the echinoid research has focused on
Diadema antillarum, and documenting its demise in
the early 1980s (Glynn 1984; Lessios et al. 1984;
Hughes et al. 2010), research on other echinoid species
is likely to add to current knowledge of their ecology.
E. lucunter is one such species that is common through-
out the Caribbean, and extends its range to Florida,
Brazil, and West Africa (McPherson 1969; Hendler
et al. 1995;Ebertetal.1999;Ebertetal.2008;
McClanahan & Muthiga 2013; Belford et al. 2019).
Two sub-species of E. lucunter have been identified in
the Caribbean (polypora and lucunter, McClanahan &
Muthiga 2013). Commonly found in shallow waters of
<10 m in depth, E. lucunter has an elliptical shape with
a maximum test diameter (measured as maximum sea ur-
chin diameter) of 150 mm, and approximately 100150
spines projecting from its central test (Hendler et al.
1995; Blevins and Johnsen 2004). It is mostly found in
shallow waters, and typically lodges itself in crevices
during the day. Although Ebert et al. (2008) noted that
E. lucunter is geographically located from North
Carolina and Bermuda through the Caribbean to Brazil
and West Africa, distribution of these species follows
the general characteristics of urchins, which at best, dis-
play patchy distributions (Dumas et al. 2007), therefore it
is difficult to explain general distribution and densities.
Average densities have been reported as 11 individuals
per m
Pomba et al. 1990), up to 129 individuals per m
(Greenstein 1993), and 240 individuals per m
(Grunbaum et al. 1978).
Currently, little is known about sea urchin colour
morphotype densities and sizes in the southern
Caribbean. Lewis and Storey (1984) noted that
E. lucunter spine colour, which plays a primary role in
determining colour morphotype were significantly different
at sites, and mentioned this variability as a result of
different food sources. McPherson (1969) noted that drift
algae was the primary food source, and Hendler et al.
(1995) stated that encrusting calcareous red algae was an-
other food source, which possibly plays a role in colour
variability in sea urchins. A wider variety of algal food
availability does result in variable expression of colour
morphotypes (Lewis and Storey 1984).
Surveys on macroalgal cover on reefs show a corre-
lation with sea urchin abundance. For instance,
Cameron and Brodeur (2007) observed highest
macroalgal cover when Diadema antillarum,
Echinometra lucunter,andTripneustes ventricosus spe-
cies were absent. Additionally, surveys also have shown
predatory fishes and a lack of safe shelters to protect
sea urchins from predation, as factors that explain den-
sity and size distribution (Alvarado 2011). Safe shelters
have been reported to harbor specific sea urchin sizes:
large crevasses support larger sea urchins, and smaller
crevasses support smaller urchins (Hereu et al. 2005).
This study aims to determine patterns in abundance,
and density of sea urchin colour morphotypes across
two habitats along the coast of this southern-most re-
gion of the Caribbean Sea. The following questions
were addressed: (1) Do sea urchins show patterns in
abundance in high and low energy environments? (2)
Are there patterns in colour morphotypes abundance in
these two habitats? Finally, (3) do coral and algae cover
have any relationship between habitat type and sea ur-
chin abundance? As in Lewis and Storey (1984), I hy-
pothesize that sea urchin colour morphotypes will be
more abundant and larger at low energy environments
compared to high energy environments, because these
urchins are protected from waves by rocky outcrops.
Additionally, I predict high densities at sites due to a
lack of visible predators. As E. lucunter is a main graz-
er of algae, benthic macroalgae coverage will be quan-
tified to determine if there is a relationship with sea
urchin abundance.
Survey Sites
The northeastern coast of Trinidad adjacent to the Caribbean
Sea has numerous undeveloped patch reefs, and the only
fringing reef of Trinidad and Tobago, West Indies, which lies
on the northeastern coastal tip, located approximately 2 km
south of the Keshon Walcott Toco Lighthouse, Galera Point
(10° 50´´N, 60° 55´ W). This fringing reef has a mixture of
sandy, rocky, and stony beaches in close vicinity of the Matura
River, which periodically has its outflow burst through its
sandy boundary during heavy rainfall. A period of low rainfall
(dry season) exists from January to late May mid-June follow-
ed by a rainy period until December. Salinity and water tem-
peratures range between 31 and 33 ppt. and 2832 °C respec-
tively, and are relatively consistent. Tides are semidiurnal with
a maximum high tide of 2 m in open water, and > 1 m low tide
Thalassas (2020) 36:157164
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Fieldwork was conducted at Pequelle Bay (SB),
which is a part of Salybia Bay reef (Site 1: 10° 50´
N, 60° 55´ W), which is a fringing reef located ~2 km
from Galera Point, that is the most northeast point of
Trinidad (Fig. 1). The reef extends ~200 m towards the
reef crest, of which approximately 180 m is accessible
by wading during lowest low tides. The reef at Grande
LAnse (GA), also known as Toco Bay (Site 2: 10°
50´N,60°55´ W) is an arrangement of underdevel-
oped patch reefs, and most of it extends ~50 m from
the shoreline, however there is a small area that ex-
tends ~80 m during lowest low tides, with ~60 m ac-
cessible from the shoreline (see Belford and Phillip
At each site, a specific rocky outcrop, only accessible
during lowest low tides was designated as an area
where sea urchins were protected from intense wave
action, that is, a low energy environment. A high ener-
gy environment was exposed to the full spectrum of
wave energy, and located close to the reef crest.
Sampling areas were no more than 250 m
where ran-
dom quadrats were used to collect data, with a maxi-
mum of 3 h of exposed lower intertidal zone
Sampling Method
All sampling was done at the lower intertidal zone
close to the reef crest, where these sites were previous-
ly selected for surveying sea urchins. Sea urchin pop-
ulation abundance and densities were collected using
the quadrat method. A 1 m × 1 m
square polyvinyl
chloride (PVC) frame was randomly tossed over each
sampling area of approximately 250 m
(N= 120 quad-
rats per site), and all sea urchins within the quadrat
were counted, with red and black colour morphotypes
(Fig. 2) separately counted to give the total sea urchin
density per m
. Abundance was calculated as total sea
urchins per site/environment. Percentage cover of ben-
thic components, such as hard coral, zoanthid, coral
rubble, invertebrate, and macroalgae coverage within
each quadrat were recorded to determine if any pat-
terns existed between sea urchin densities and benthic
Sea urchin colour morphotypes were randomly select-
ed from each quadrat, and a 20 cm stainless steel micro
spatula with flattened ends was used to gently pry ur-
chins from their benthic substrate. Fragments and algae
lodged between individual spines were manually re-
moved before measurements. Test diameter was mea-
sured using a hand caliper to the nearest 0.1 mm. A
digital hand-held scale was used to measure the weight
of the urchin. All measurements were completed no
longer than 45 s. for each urchin, and urchins were
returned to their aquatic habitat immediately after all
data were recorded. All measurements were done during
a short period of a few weeks in June, which provided
a brief window where turbidity and accessibility were
not an issue, hence the reason to collect data over the
time period mentioned above.
All results gathered from populations of Echinometra
lucunter were sampled at a patch and fringing reef ap-
proximately 3.5 km distance apart, along the northeast-
ern coast of Trinidad, West Indies in order to determine
Fig. 1 Map showing the location of Trinidad relative the Caribbean (left) and the study sites located on the northeastern coast of Trinidad (right)
illustrating the distance of the only marine protected area at Buccoo Reef, Tobago (see Belford and Phillip 2011)
Thalassas (2020) 36:157164 159
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if sea urchin abundance, densities, and sizes were sim-
ilar at these reefs. Sampling was conducted during ex-
treme low tides (0.2 m depth) early June 2015, 2016,
and 2017 over a 1-week period at Pequelle Bay (SB)
reef and Grande LAnse (GA) reef, at habitats associat-
ed with low and heavy wave action.
Data Analysis
A general linear model, such as Analysis of Variance
(ANOVA) was used to compare sea urchin test diam-
eter and weight between years, sites, colour
morphotypes (black and red), and type of environment
(low and high wave action). Test diameter data and
weight recorded were used to analyze correlation. To
test for differences in size between different habitats
and sites, data for test diameter and weight were an-
alyzed using ANOVA.
In 2015 sea urchin densities at Salybia Bay (SB) were
30.5 urchins per m
in low wave action areas compared
to 14.9 urchins per m
in areas of high wave action. At
Grande LAnse reef (GA) 58.0 sea urchins per m
recorded at low wave action areas compared to 9.9 ur-
chins per m
in high wave action areas. In 2016 sea
urchin densities at SB were 60.7 per m
in low wave
for GA were 53.0 urchins per m
in low wave action
in areas of high wave action. For 2017
densities were 60.0 urchins per m
in low wave action,
in high wave action at SB
compared to 25.2 urchins per m
in low wave action
and 16.2 urchins per m
in high wave action at GA
respectively. Altogether higher sea urchin densities were
observed in low wave action (protected), compared to
high wave action (open).
Although sea urchins were just as abundant at both
sites, black colour morphotypes were significantly more
abundant than red morphs (p< 0.05), hence also more
abundant in high versus low wave action environments.
Sea urchin abundance at each site was categorized as
dominant with an average of 25 urchins or more per
quadrat, followed by average between 5 to 25 urchins
per quadrat, and low abundance at less than 5 urchins
per quadrat. Overall, for all years (2015, 2016, 2017)
sea urchins at low wave action habitat were dominant at
both sites, however sea urchins were only abundantly
average if they were found in high wave action.
Interestingly, black colour morphs were abundantly
dominant in low wave action habitat for all years, how-
ever red colour morphs showed average abundance. In
high energy wave action habitat black colour morphs
were abundantly average, whereas red colour morphs
showed low abundance.
Test diameter showed a strong correlation with sea
urchin weight at each site for all years, therefore justi-
fying these parameters as a measure of size (correlation
coefficients 2015: r = 0.91 (SB) r = 0.92 (GA); 2016: r =
0.87 (SB) r = 0.78 (GA); 2017: r = 0.72 (SB) r = 0.90
(GA)). Overall sea urchin mean test diameters (± SD)
for high wave action were 29.68 mm ± 8.03 (2015),
33.69 mm ± 6.76 (2016), and 32.11 mm ± 10.81 (2017).
Test diameter mean (± SD) for low wave action were
33.84 mm ± 12.64 (2015), 38.76 mm ± 9.24 (2016), and
38.18 mm ± 10.44 (2017). Thus urchins in low wave
energy habitat were more likely to be larger for both
colour morphotypes. Sea urchins in both habitats and
at both sites for each year were more likely to have a
test diameter ranging from 21 to 60 mm in length
(Fig. 3a-c), which is typically small (139 mm), and
medium (4060 mm). However, sea urchins with the
largest test diameters (6170 mm), which are defined
as large (61100 mm) were more likely to be found
in areas of low wave action (see Appana et al. 2004
for size classes).
There was a significant increase in sea urchin size
amongst years for test diameter (ANOVA, F2, 321 =
8.33, p< 0.05), and weight (ANOVA, F2, 305 = 3.88,
p < 0.05). Sea urchins at sites for each year showed
significant differences in test diameter and/or weight at
PB, and GA (ANOVA, p< 0.05). Black colour morphs
had significantly larger test diameters than red morphs
(ANOVA, F2, 175 = 5.55, p < 0.05). Additionally, sea
urchins in low energy environments were significantly
larger than those found in high energy environments for
all years (t-test, p<0.05).
Mean test diameter was significantly larger for the
red colour morphed urchins in low wave action, that
is, rocky protected areas versus high wave action, or
open areas at SB in 2015 (t-test, t = 4.41, p<0.05,
Fig. 4a) and 2016 (t-test, t = 2.25, p < 0.05, Fig. 4
Fig. 2 Red and black colour morphotypes observed at Pequelle and
Grande LAnse Bays, Toco, Trinidad
Thalassas (2020) 36:157164
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c), and also for black colour morphs in 2016 (t-test,
t=2.67, p< 0.05, Fig. 4c). In 2017, mean test diame-
ter was significantly larger for the black colour
morphed urchins living in low wave action habitat (t-
test, t = 3.44, p< 0.05, Fig. 4e). Mean weight of red
morphs in low wave action habitat was significantly
heavier than that of red colour morphs in open habitat
at SB in 2015 (t-test, t = 4.97, p < 0.05, Fig. 4b).
Results for 2016 showed red colour morphs in rocky
habitat significantly weighed more than red colour
morphs in open habitat at GA (t-test, t = 2.17, p <
0.05, Fig. 2d). Mean weights showed no significant
increase or decrease for either colour morphs in 2017.
Both sites are dominated by 3550% zoanthid coverage
(see Belford and Phillip 2011,2012), with scleractinian corals
maintaining 1015% coverage throughout the reefs.
Macroalgae coverage recorded 1015% in each year. Fish
diversity includes members represented from a variety of fam-
ilies, such as Chaetodontidae, Acanthuridae, Scombridae,
Pomacentridae, and Muraenidae.
For the first time in Trinidad, sea urchin abundance, density,
and size in low and high wave action habitats were surveyed
over brief periods during a 3-year duration at shallow reefs
along the north-eastern coast. Both sea urchin colour morphs
were abundantly dominant in low wave action habitat, which
was similarly reported for Echinometra lucunter by Lewis and
Storey (1984). Abundance was average for black morphs and
low for red morphs in high wave action. Lawrence and Kafri
(1979) suggested that urchins in high wave action may suffer
higher mortality in general, and the dominant abundance of
sea urchins in low wave action protectedhabitat, may be the
result of a lack of predation from fishes, as fish predation has
been seen to cause differences in abundance and size distribu-
tion in sea urchins (Guidetti 2007;Comaetal.2011).
Black colour morphotypes had highest densities at both
sites, and this morph continued to show high densities at
low wave energy environments. Similar results were
encountered by Lawrence and Kafri (1979) illustrating greater
urchin densities in protected areas. In contrast, not all sea
urchin species show this characteristic, as Echinometra
mathaei and Echinometra oblonga aremoredominantinhigh
wave action habitat (Russo 1977). Other biota in close vicinity
to urchins were surveyed to determine if there were any pat-
terns that existed with urchin densities, however no such pat-
terns were recorded. The black colour morph made up the
dominant type on reefs, but similar differences in size and
weight were recorded for both black and red morphs in low
Although this species can reach 150 mm in size (Hendler
et al. 1995), most urchins in this study were 2150 mm, with
largesttestdiameterreportedat5170 mm. The densest sizes
(2150 mm range) also were found in both low and high
energy environments, however significantly larger urchins
were found in low energy environments at both sites. Lewis
and Storey (1984) found similar results, but no mention was
made to colour morphotypes of E. lucunter, therefore this
study did reveal similar results for both colour morphs.
Appana et al. (2004) reported significantly small
Echinometra sp. (139 mm) dominating the reef crest (high
0-10 11-20 21-30 31-40 41-50 51-60 61-70
Test Diameter (mm)
0-10 11-20 21-30 31-40 41-50 51-60 61-70
Test Diameter (mm)
0-10 11-20. 21-30 31-40 41-50 51-60 61-70
Test Diameter (mm)
Fig. 3 Variation in sea urchin size frequency at Pequelle Bay reef (SB =
Black bars) and Grande LAnse reef (GA = White bars) for (a) June 2015,
N= 72 SB, 70 GA, (b)June2016,N= 58 SB, 51 GA, and (c) June 2017,
N= 24 SB, 55 GA
Thalassas (2020) 36:157164 161
Author's personal copy
wave action), with larger individuals (61100 mm) absent.
Additionally, this study showed near normal distribution of
sea urchin size classes found in both habitats, which also
was reported on Fijian reefs (Appana et al. 2004).
Macroalgae cover throughout this study was considerably
low in comparison to other studies in the Caribbean, which
highlight its dynamic role on benthic communities. For exam-
ple, Olson and Steneck (2007) mentioned a significant in-
crease in macroalgae coverage coinciding with a decline in
parrotfish population in Bonaire during 2003 and 2005, which
resulted in declining reef species. However, a 2007 study stat-
ed that Bonaire reefs had improved, due to macroalgae abun-
dance of 5%, due to an increased in herbivores, such as sea
Zoanthids have been recorded to occupy different zones
according to the nature and type of habitat. For example,
Belford and Phillip (2012) noted that Zoanthus sociatus colo-
nized stressed areas where exposure was the greatest, com-
pared to Palythoa caribaeorum colonies, which preferred less
stressed areas on the reefs. Unlike sea urchins, which can
borrow into crevasses when desiccation increases due to ex-
treme low tides, specific zoanthids may or may not occupy
high wave action areas, which become exposed for at least 3 h
during extreme low tides. Moreover, distribution of
Z. sociatus and P. caribaeorum is related to desiccation toler-
ance (Herberts 1972), whereas E. lucunter colour morph dis-
tribution does not appear to have a determining factor, except
for size being determined by low or high energy
Sea urchin distributions in this study were clumped, but
may generally be patchy, with densities varying from 0 to
100 urchins per m
(Dumas et al. 2007). Moderately dense
concentrations were reported in this study 3033 urchins per
compared to 11 per m
(Pomba et al. 1990) and 111 ur-
chins per m
quadrat (this study) compared to 129 urchins
(Greenstein 1993). Even though moderate densities were re-
ported in this study, Young and Bellwood (2011) noted that
densities may be underestimated, because of urchin activity.
Higher densities are seen at night when most urchins are ac-
tive, however this study collected urchin data during the day,
and at extreme low tides, where access was readily easy at
both energy-related environments.
Both sites are generally unfished areas, therefore urchin
densities are not lost by fishing nets. No attempts were made
Fig. 4 Mean test diameter and weight for sea urchin colour morphotypes
in relation to habitat type at Salybia Bay reef (SB) and Grande LAnse
reef (GA) are illustrated in (a) SB Rocky versus SB Open mean test
diameter in June 2015 (b) SB Rocky versus SB Open mean weight in
June 2015 (c) SB Rocky versus SB Open mean test diameter for both
colour morphs at SB in June 2016 (d) GA Rocky versus GA Open mean
weight in 2016, and (e) SB Rocky versus SB Open mean test diameter in
June 2017. Significant differences (ANOVA, p< 0.05) and error bars
indicate standard error
Habitat Type
Mean Weight (g)
Habitat Type
Habitat Type
Mean Weight (g)
Habitat Type
Habitat Type
Thalassas (2020) 36:157164
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to record urchin densities at night due to the inaccessibility of
these sites, as a result of unpredictable wave action. Urchin
movement away from their shelters have been documented at
night (Carpenter 1986; Young and Bellwood 2011), therefore
this may be worth investigating in a future study.
Overall, both colour morphs distribution on reefs are too
variable to justify a specific pattern. Except for low energy
environments at Pequelle Bay in 2015, both colour morphs
showed stable densities in both environments at both sites.
Once again it should be noted that urchin numbers may be
under-represented, which may deem a night study focusing on
densities necessary.
Acknowledgements This work was supported by partial funding from
the Martin Methodist College Biology department, alumni council, and
International Studies department. Field assistants involved in some data
collection were Bradley Crye, Markeyta Bledsoe, Madeline Woods,
CalliAnna McDonald, and Douglas Dorer. Dawn A.T. Phillip is credited
for field observations that were instrumental to the development of this
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... were most common in shallow waters (<5 m), as reported at sites along the west coast of Curaçao [11]. In fact, Belford and Phillip [9,10,12,28] highlighted zoantharians being more abundant than their Scleractinia counterparts at this study's main sites. Lopez et al. [29] ob-served extensive zoantharian coverage for species Zoanthus solanderi and Zoanthus sociatus at a "zoanthid zone" located at Cabo Verde Islands, central eastern Atlantic,. ...
... Reimer et al. [20] reported variation in Palythoa sp. polyp form and color as a result of variable environments, such as degree of wave action, and benthic type, which were characteristics similarly observed at Toco, Trinidad [9,10,12,28]. ...
Full-text available
Zoantharians are colonial cnidarians commonly found in shallow tropical Caribbean coral reefs, and are known to be globally distributed. Common species in genera Zoanthus and Palythoa occur at Toco, Trinidad, where they are more abundant than their Scleractinia counterparts relative to benthic coverage. In this study, distribution, morphological and molecular data were collected to determine species and symbiont identification to provide more insight on zoantharians. The Line Intercept Point (LIT) transect method recorded coverage at three sites: Salybia (SB), Pequelle (PB), and Grande L’Anse (GA) Bays along the northeastern coast. Variations in morphology, such as tentacle count, oral disk color and diameter were collected from colonies in situ. All specimens were zooxanthellate, and molecular and phylogenetic analyses were done by sequencing the cytochrome oxidase subunit I (COI) gene, and the internal transcribed spacer (ITS) region for species and symbiont identification, respectively. Results showed mean Zoantharia percentage cover was 32.4% ± 5.1 (X ± SE) at SB, 51.3% ± 6.5 (PB), and 72.2% ± 6.1 at GA. Zooxanthellate zoantharians were identified as Palythoa caribaeorum, Palythoa grandiflora, Zoanthus pulchellus, and Zoanthus sociatus. Symbiodiniaceae genera were identified as Cladocopium and Symbiodinium in Palythoa and Zoanthus spp., respectively. Although this is the first molecular examination of zoantharians, and their symbionts in Trinidad, more research is needed to identify and document species distribution and symbiont biodiversity to understand their ecology in these dynamic ecosystems.
Full-text available
A survey of the biological diversity of coral and associated reef organisms was conducted for the Salybia and Grande L'Anse reefs along the northeastern coast of Trinidad by reviewing the literature, museum collections, and conducting field surveys between the years 2005 through 2019. Surveys conducted used the line and point intercept and quadrat techniques to gather data. If unidentified and incompletely identified specimens are not included, this study found 257 species belonging to 134 families, 23 classes, and 11 phyla. Most species belonged to Mollusca (75 species), Chordata (57), Cnidaria (43) and Arthropoda (33). Despite their proximity to each other, only 42 species were common to both reefs. Of the other species, most (178) were found at Salybia Reef. Only members of Phylum Porifera showed a greater species richness at Grande L'Anse Reef than Salybia Reef, with five and two species, respectively. This is the first complete marine biodiversity survey for the most northeastern part of Trinidad, which includes the only fringing coral reef in Trinidad. Coral reef monitoring is essentially important in this area, as there are current plans to build a port at Grande L'Anse Reef, thus potentially destroying a valuable area of the coral reef network observed along the northeastern coast of Trinidad.
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Coral reefs across the world’s oceans are in the midst of the longest bleaching event on record (from 2014 to at least 2016). As many of the world’s reefs are remote, there is limited information on how past thermal conditions have influenced reef composition and current stress responses. Using satellite temperature data for 1985–2012, the analysis we present is the first to quantify, for global reef locations, spatial variations in warming trends, thermal stress events and temperature variability at reef-scale (~4 km). Among over 60,000 reef pixels globally, 97% show positive SST trends during the study period with 60% warming significantly. Annual trends exceeded summertime trends at most locations. This indicates that the period of summer-like temperatures has become longer through the record, with a corresponding shortening of the ‘winter’ reprieve from warm temperatures. The frequency of bleaching-level thermal stress increased three-fold between 1985–91 and 2006–12 – a trend climate model projections suggest will continue. The thermal history data products developed enable needed studies relating thermal history to bleaching resistance and community composition. Such analyses can help identify reefs more resilient to thermal stress.
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The spatial variability of Echinometra lucunter, Lytechinus variegatus and Arbacia lixula was studied in relation to four spatial scales (105, 104, 103 and 102 m) and two depths (0-3 and 3-8 m), along 100 km of the São Paulo coastline (August to October 1996). Echinometra lucunter was the most abundant species, with preference for shallow substrates subject to wave action. An abundance gradient was identified, increasing from southwest to northeast. Arbacia lixula showed the same pattern of spatial variation, but was more abundant in the deeper areas. Both species showed significant differences on a spatial scale of hundreds of meters, and E. lucunter also on a scale of kilometers. Lytechinus variegatus presented a patchy distribution, being more abundant at certain sites. Variations in the water quality and natural heterogeneity of the habitat may explain the spatial distribution of these populations.
The Phylum Echinodermata, comprising approximately 7,000 living species, and 13,000 fossil species, is epitomized by the familiar sea star, a universal symbol of the marine realm. This distinctive group of animals may be briefly defined as possessing a skeleton of calcium carbonate in the form of calcite; a unique water-vascular system which mediates feeding, locomotion, and other functions; and a more or less conspicuous five-part radial symmetry. A closer look at some extant echinoderms will show that some taxa of sea cucumbers lack calcite in their body walls, some taxa of sea stars have “outgrown” five-part symmetry and may have 50 or more arms, and many echinoderms show a more or less conspicuous bilateral symmetry superimposed upon a radial pattern. Fossil echinoderms can be even more puzzling, for some are decidedly asymmetrical, and others may lack evidence of a water-vascular system. Perhaps the only truly reliable taxonomic character of the phylum is that its members today are restricted to the marine realm.
Tropical reef systems are transitioning to a new era in which the interval between recurrent bouts of coral bleaching is too short for a full recovery of mature assemblages. We analyzed bleaching records at 100 globally distributed reef locations from 1980 to 2016. The median return time between pairs of severe bleaching events has diminished steadily since 1980 and is now only 6 years. As global warming has progressed, tropical sea surface temperatures are warmer now during current La Niña conditions than they were during El Niño events three decades ago. Consequently, as we transition to the Anthropocene, coral bleaching is occurring more frequently in all El Niño–Southern Oscillation phases, increasing the likelihood of annual bleaching in the coming decades.
Live (biocoenoses) and dead (taphocoenoses) populations of regular and irregular echinoids inhabiting shallow water environments of San Salvador and Leestocking Island, Bahamas have been censused to test Kier's (1977) hypothesis that the relatively poor fossil record of the regular echinoid is the result of taphonomic bias. In general, results reveal that distributions of living regular echinoids are not reflected by accumulations of their carcasses, while the reverse is true for irregular taxa: subfossil material is more often associated with living populations suggesting that irregulars may have relatively greater likelihood of preservation. -from Author
Coral cover on Caribbean reefs has declined rapidly since the early 1980's. Diseases have been a major driver, decimating communities of framework building Acropora and Orbicella coral species, and reportedly leading to the emergence of novel coral assemblages often dominated by domed and plating species of the genera Agaricia, Porites and Siderastrea. These corals were not historically important Caribbean framework builders, and typically have much smaller stature and lower calcification rates, fuelling concerns over reef carbonate production and growth potential. Using data from 75 reefs from across the Caribbean we quantify: (i) the magnitude of non-framework building coral dominance throughout the region and (ii) the contribution of these corals to contemporary carbonate production. Our data show that live coral cover averages 18.2% across our sites and coral carbonate production 4.1 kg CaCO3 m−2 yr−1. However, non-framework building coral species dominate and are major carbonate producers at a high proportion of sites; they are more abundant than Acropora and Orbicella at 73% of sites; contribute an average 68% of the carbonate produced; and produce more than half the carbonate at 79% of sites. Coral cover and carbonate production rate are strongly correlated but, as relative abundance of non-framework building corals increases, average carbonate production rates decline. Consequently, the use of coral cover as a predictor of carbonate budget status, without species level production rate data, needs to be treated with caution. Our findings provide compelling evidence for the Caribbean-wide dominance of non-framework building coral taxa, and that these species are now major regional carbonate producers. However, because these species typically have lower calcification rates, continued transitions to states dominated by non-framework building coral species will further reduce carbonate production rates below ‘predecline’ levels, resulting in shifts towards negative carbonate budget states and reducing reef growth potential.