If such observations can be made in other parts Dominica, a minimal (albeit very slow) recovery of this species in Dominica may be possible. Orbicella annularis is among the most important components of framework building stony corals in Dominica's. Its continuous loss of live cover throughout the island, had been pointing at a collapse of the these structural components.
The invasive seagrass Halophila stipulacea, appears to persist as dominant seagrass along the west coast, where its explosive expansion between 2007 and 2012 had replaced all native seagrass meadows. I did not have a chance to see whether the remaining native strongholds of Syringodium filiforme still existed and whether H. stipulacea had penetrated the north coast, which it hadn't up to 2013. Compared to previous visits, juvenile fishes were much more common within the invasive seagrasses and there was an abundance of a dark brown, branching sponge (Haliclona sp. ?) on H. stipulacea that I had not seen before in Dominica.
Earlier this year, Kramer et al. (2016) published Dominica’s Coral Reef Report Card 2016. A substantial amount of information used to create the document was derived from this site and the studies made by students and staff of ITME (see www.itme.org/reports). Hopefully, the Coral Reef Report Card will help in reaching a wider audience and in facilitating a better understanding of the scale of Dominica´s coastal marine habitats and the chronic impacts to which they are exposed.(see also Steiner 2015).
Kramer PR, Roth LM, Constantine S, Knowles J, Cross L, Steiner S (2016). Dominica’s Coral Reef Report Card 2016. The Nature Conservancy.
Alternative Link to Document
Steiner SCC (2015) Coral Reefs of Dominica (Lesser Antilles). Ann. Naturhist. Mus. Wien, B, 177:47-119.
SCC Steiner, 09.2016
Please cite: Steiner,
SCC (2016) Marine Habitats of Dominica: Status update 2016. (http:www.itme.org/mhdm/status.htm),
of Marine Habitats 2013
underwater landscape along Dominica's near shore marine environments
continues to change rapidly.
coral cover continues to decline. Even those reefs that were among
the healthiest in terms of (a) their live coral cover (15-20%) and
species richness, (b) the presence of large living coral frameworks,
and (c) a diverse array of reef fishes and invertebrates, up to
2008 (e.g. Grande Savane and Mero) have deteriorated at a pace unprecedented
since our first records from 1999. Coupled with the multiple chronic
stressors described in earlier status descriptions from 2007 and 2008 (below), coral bleaching
in 2010 further expedited this degradation. Virtually all previously
remaining coral frameworks that still harbored considerable live
coral cover are now skeletal ruins overgrown by algae. At
a time when a the first detailed island-encompassing documentation
of Dominica's coral reefs has been completed, the outlook on the
survival of the few remaining coral reef communities is disheartening
like never before.The
forthcoming paper Coral Reefs of Dominica, by SCC Steiner,
provides a detailed look at the current status.Abstract Systematic investigations on corals
reefs of Dominica began in 1999 with the establishment of the Institute
for Tropical Marine Ecology on the island. Taking into account the
geological and oceanographically traits of this volcanic island,
and its history of marine investigation, this report summarizes
data on the distribution and morphology of reefs and coral assemblages,
based on studies carried out between 1999 and 2013. It is the island-encompassing
account, describing 31 coral reefs and 27 coral assemblages, including
46 species of stony corals (Scelarctinia, Anthozoa) and 4 species
of hydrocorals (Anthoathecata, Hydrozoa). The present condition
of Dominica's reefs is discussed in view of historic resource uses
and the current exposure to sediment inputs, solid waste, effluents,
fisheries and tourism. Perpetuated misconceptions on the location
and size of the island's reefs are depicted and guidelines for their
preservation are outlined.
most drastic change in the underwater landscape has been induced
by the explosive expansion of Halophila stipulacea which
replaces most native seagrass meadows and caused a cascade of changes
in Dominica's western sublittoral.The
forthcoming paper The expansion of Halophila stipulacea (Hydrocharitaceae,
Angiospermae) is changing the seagrass landscape in the Commonwealth
of Dominica, Lesser Antilles, by SCC Steiner and DA Willette,
provides a comprehensive account of the recent changes. Abstract The seagrass Halophila stipulacea, alien to the
Caribbean, was first reported from Dominica in 2007, where its rapid
growth and ability to supplant native species, as well as the profiles
of native seagrasses meadows were established in 2008. In 2013 we
reexamined 27 meadows and observed a highly altered underwater landscape
along Dominica's west coast (leeward) and unchanged seagrass
beds along the northeast (windward). On the western sublittoral,
pure stands of H. stipulacea replaced most Syringodium
filiforme meadows and Halodule wrightii in depths greater
than 4 m, as well as all Halophila decipiens stands and meadows.
Fauna and flora occurring within seagrasses was concentrated in
the remaining native seagrass stands. We identified three scenarios
of increasing impact by H. stipulacea; "native strongholds"
of pure native stands, "invasive takeovers" where native
seagrasses were completely replaced, and "new meadows"
in areas previously free of seagrasses. The area covered by Dominica's
seagrasses doubled from an estimated 316 ha in 2008 to 773 ha in
2013; driven exclusively by the spread of the alien seagrass. Benefits
and losses of the recent angiosperm invasion are unforeseeable,
yet the remaining strongholds and the unchanged north coast meadows,
point at ecological limitations in the invasibility of native seagrasses
and environmental circumstances that foster refugia for some native
species. However, based on the increasing number of sightings H.
stipulacea in the Lesser Antilles, we predict large-scale alterations
in the architecture and species composition of seagrass meadows
throughout the Caribbean within the next decade, and the demise
of H. decipiens.See our main reports page for details. www.itme.org/reports.htm
Please cite: Steiner,
SCC (2013) Marine Habitats of Dominica: Status update 2013. (http:www.itme.org/mhdm/status.htm),
(Jan 2015 UPDATE 1: New paper on coral reefs of Dominica Also see our main reports page for related papers. www.itme.org/reports.htm.)
(Jan 2015 UPDATE 2: New paper on invasive seagrass in Dominica. See our main reports page for new papers. www.itme.org/reports.htm)
of Marine Habitats 2008
the past year, the analysis of the data collected during ITME's
2007 large-scale habitat survey has revealed interesting new perspectives
on Dominica's marine resources. The single largest surprise was
the extent of seagrass beds in Dominica. We now know that these
are the largest marine habitats in Dominica created by organisms.
With ca. 266 ha+, their cover far surpasses that of coral reefs.
Furthermore, the new results largely contradict the few governmental
and non-governmental reports mentioning the distribution of marine
habitats, which appear to not have been based on field surveys.
studies on Dominica's benthic communities up to 2007 focused on
coral reefs and assemblages. Only 8.6 ha of reef surveyed last year
had previously not been recorded. It has been clear that coral reefs
are marginal communities on the narrow shelf of Dominica, but just
how marginal is now apparent considering that they only cover approximately
81 ha. This finding does not support non-governmental reports listing
700 ha of coral reefs in Dominica. Even when considering coral assemblages
found in some of Dominica's rocky environments, characterized by
a lack of reef accretion as "coral reefs", the benthic
cover would be far below 700ha.
concrete figures now available for the distribution and dimensions
of Dominica's marine resources provide a key reference point for
future and past studies. Given the extensive distribution of seagrasses,
new studies were launched in 2008, focusing on the horizontal zonation
patterns in local seagrass beds. These on-going studies which include
the deeper seagrass beds not surveyed in 2007, are providing additional
insights into the distribution and benthic cover of the five so
far identified seagrass species (see organism
lists). Furthermore, it has become clear that the distribution
of invasive H. stipulacea (as initially reported by D. Willette),
is far more extensive than anticipated.
most recent studies, revisiting existing species
inventories, fell within the impact of Hurricane Omar. Although
not directly affecting Dominica, its south-eastern windbands led
to strong surge along the west coast, causing coastal erosion and
flooding. In rocky habitats, large numbers of sessile invertebrates
and algae were uprooted. In sandy environments, extensive shifts
in sand were noticed. Seagrass beds in some cases (narrow shelf)
disappeared completely due to a combination of burial and erosion.
Anthropogenic debris and lost fishing gear (gill nets, boats, pots,
engines) also caused considerable damage to reefs. In particular
large nets became death traps for many invertebrates, fishes and
turtles. Given this strong disturbance, recent findings on the distribution
and abundance of selected organism groups were rather conservative.
event, however, highlights the impact of natural disturbances in
narrow shelf settings, and how this has shaped the distribution
of marine habitat types in Dominica. It also serves as a reminder
that the mitigation of local human-induced and enhanced disturbances
remains a key element in any attempt to slow down or stop the degradation
of Dominica's near-shore marine resources.
sediment input increased via coastal construction and dumping, solid
waste (degradable and non-degradable) and fishing pressure are the
negative local disturbances apparent to anyone who spends some time
exploring Dominica's coastal waters.
Please cite: Steiner,
SCC (2008) Marine Habitats of Dominica: Status update 2008. (http:www.itme.org/mhdm/status.htm),
of Marine Habitats 2007
activity along Dominica's shores can be traced back several thousand
years, but the heaviest uses are likely to have started in the mid
1700s with the first concerted settlement attempts by the French
and British. See the writings by Dr. Lennox Honychurch for further
historical information at www.lennoxhonychurch.com
steep terrain of this young volcanic island (with its recent volcanic
formations occurring less than 1.8 million years ago) is evident
in its narrow shelf area and rugged interior. Settlements have historically
sought the coastal zones and in particular the valleys opening to
the sea. Valleys offer the best arable land, easy access to inland
areas and water which became an important source of energy for the
mills of Dominica's estates. This scenario has put marine life and
habitats in close proximity with population centers. Herein lie
the main sources of marine environmental degradation.
runoff from land, a natural process, is exacerbated by activities
such as deforestation for agriculture, logging and other activities
and purposes. In essence, any activity that decreases the sediment
retention (for example via vegetation) of a particular area leads
to increased terrestrial runoff. Increased sedimentation due to
infrastructural development and sand/gravel quarrying are among
the recent sources of this type of disturbance. The negative impacts
of this process include the suffocation of marine organisms, weakening
of animals allocating excessive energy to rid themselves of sediment,
and decreased light levels affecting photosynthetic organisms. The
consequences can bee seen in the burial and consequent death of
coral assemblages (Fond Cole) and sea grass habitats (West Coast).
coastal zone degradation comes in many forms. The most evident is
the illegal and legal dumping of building materials, as well as
industrial and household refuse. Unfortunately, evidence of this
activity is commonly seen throughout the island. Once submerged
in the sea, these materials are out of sight and out of mind for
some, but strong storms and hurricanes occasionally spit these materials
back onto allowing for reconsideration of this practice.
humans add materials into the sea, and the concentration of these
"additions" exceeds the natural background levels, we
speak of contamination. When contamination leads to the degradation
of marine habitats and or human health, as well as human interests
in marine resources, pollution is the term used by international
conventions. Measurements of marine pollution in Dominica have not
been carried out to date. Signs of contamination, however, are evident
in the vicinity of population centers. The clearest signs come in
the form of household and industrial waste and debris, which physically
damages habitats and sessile organisms, and increased algal cover.
forms of degradation arise from the extraction or harvesting of
marine life. Both the extraction techniques applied and the biomass
removed can lead to the collapse of individual species or lead to
phase shifts within entire ecosystems. The narrow sublittoral zone
of Dominica represents a limited resource. Therefore, the multitude
of fishing techniques (line and hook, fish pots, seine nets, and
spear fishing) used for the past centuries have depleted reef fish
communities in Dominica to a point many species are rarely seen
and large reef / near-shore demersal pelagic fishes are an uncommon
sight. Slow growing coral reefs are being out-competed by fast-growing
algae as there are not enough grazers to keep the algae in-check.
Similarly, larvae of sessile organisms find little new space (generated
by grazing) to settle and the live cover of reef corals in Dominica
is steadily decreasing as a result of the aforementioned disturbances
and the emergence of more frequent regional disturbances.
no longer practiced today, mining of stony corals for the production
of lime necessary in construction prior to the availability of cement,
was common practice from the 1770s up into the mid 1900s. It is
unclear how much habitat was lost this way, but it is a form of
degradation that preceded what we are doing to coral reefs today.
disturbances include the rise of sea surface temperatures linked
to global warming. These events have increased in frequency and
intensity in recent decades. In 2005, elevated sea surface temperatures
led to the severest bleaching episode ever recorded for the Caribbean.
It was centered in the NE Caribbean, and Dominica was one of the
islands whose coral reefs suffered the most. The loss of live coral
cover and the virtual absence of particular species were the result
of this event (that followed closely on the heels of the bleaching
events of 2003 and 2004). These disturbances lead to the weakening
of species and ecosystems, which, alone, may not kill a species
or habitat, but when combined with multiple other local disturbances,
individual species or habitats have already. The recent increase
in coral diseases may be linked to such conditions: where corals
weakened by local and global stressors become more susceptible to
disturbances are not easily mitigated by small island nations and
this highlights the urgency of immediate action in reducing local
disturbances if the island's coral reef resources are to have a
chance of being conserved.
species can pose problems in several ways. They can out-compete
local species, possibly taking over entire habitats, and they may
carry other organisms like bacteria with them that could affect
local species. The ballast water from boats and ships is one common
means of invasion by such species. Airborne sources (Sahara Dust)
of introductions have also been documented in a collaboration (2002)
with R. Armstrong (U Puerto Rico).
stony coral Tuastraea coccinea is invasive and currently
can be found in the Scott's Head Soufrier Marine Reserve. Its distribution
is being monitored by S. Steiner. It is not a reef-building species
and tends to remain in small patches. To date, these patches are
spread of a few 100 m2.
much greater concern is the widespread presence of the invasive
seagrass Halophila stipulacea documented by D. Willette. This is an aggressive species that can
out-compete the local seagrass species. It seems that Prince Rupert's
Bay may be the area where this species was introduced, and has been
recorded along most of the west coast between Fond Cole and Lamothe
Please cite: Steiner,
SCC (2007) Marine Habitats of Dominica: Status update 2007. (http:www.itme.org/mhdm/status.htm),