Baird,
A.H., Babcock, R.C. and C.P. Mundy. 2003. Habitat selection by larvae
influences the depth distribution of six common coral species. Marine
Ecology Progressive Series 252:289-294.
It
is commonly held that depth distributions of stony corals are mediated
by environmental factors such as light levels and water motion, as well
as biological interactions such as competition and predation. It is also
commonly held that these mechanisms control the survival of coral larvae
when they settle. In other words, the coral larvae will settle
non-differentially over a wide depth gradient and they either survive or
perish based on the previously mentioned factors. This study takes a
different view and proposes that coral larvae preferentially choose
where to settle based on the substratum of the parental habitat. That is
to say that larvae of corals that are normally found in shallow areas,
will preferentially settle in shallow areas, corals from deeper areas
will settle there while those with wide depth distributions will show no
preference.
In
order to test this hypothesis six coral species were chosen at a study
site on the Great Barrier Reef. These six species showed a marked
difference in depth distribution. The study site was Pelorus Island,
which lies about 18 km off the eastern Australian coast in the central
Great Barrier Reef. Being so close to the mainland, water clarity was
low with 8 to 10 meters visibility the norm.
Table
1 shows the species and their relative abundances by depth as determined
by belt transect surveys. Clay paving tiles were placed at 2 m and 12 m
depths and conditioned by leaving them there for 8 weeks bolted to
concrete blocks. The experiment consisted of placing three tiles from
each depth plus three unconditioned tiles in open system tanks with one
species of coral larvae (several thousand to several hundred depending
on the species). The larvae were added and then given 10 days to settle
and undergo metamorphosis after which time the tiles were examined and
the settled corals counted.
Table
1. Number of each species found at three depths as measured within six
15 x 0.5 m belt transects at Pelorus Island.
Species
2
m
6
m
12
m
Goniastrea
aspera
67
4
0
Goniastrea
retiformis
54
6
0
Fungia
horrida
1
0
21
Fungia
repanda
0
4
28
Platygyra
daedalea
17
23
18
Leptoria
phyrgia
15
13
14
The
results showed a distinct preference by the larvae for tiles from the
parental habitat. Both Goniastrea species showed a high affinity
for the 2 m tiles over the 12 m and unconditioned tiles. The two fungid
species showed an affinity for the deeper tiles, and the Platygyra
and Leptoria species showed a nearly equal distribution between 2
m and 12 m tiles.
The tiles were
also examined for the organisms that had grown on them while they had
been on the reef. The difference in distribution of the Goniastrea
species was mirrored by the abundance of crustose red coralline algae on
the 2 m tiles. Deeper water tiles had a greater abundance of tunicates,
bryozoans, sponges and polychaete worms. Zone-specific coralline algae,
bacteria and microalgae that have been shown to be important settlement
cues in other studies were unfortunately, not examined in this study.
Although
this study shows that settlement can be induced by the presence of
depth-related organisms, it was not 100%. Therefore, other cues also
play a role in the choice of settlement site by the coral larvae i.e.
light intensity and spectral quality. More importantly, this study shows
that, when given a choice, coral larvae can actively choose where to
settle. This suggests that the depth distribution of adult colonies is
influenced by patterns established at settlement and that these
settlement cues are most likely species specific.
This
study may have implications for commercial live coral aquaculture
operations that hope to supply the aquarium hobby with captive grown
corals via sexual reproduction of coral planulae. Unless the proper
settlement cues are available, recruitment may be lower than desired.
For this reason, knowledge of not only the natural distribution of a
coral species over a depth range but also the fouling communities found
at these locations might be critical for those species with narrow depth
distributions.
Olivotto,
I, Cardinali, M., Barbaresi, L., Maradonna, F. and O. Carnevali. 2003.
Coral reef fish breeding: the secrets of each species. Aquaculture
224(1-4):69-78.
I
must confess, when I first came across this paper, I thought I had hit
the holy grail of ornamental fish aquaculture! However, that excitement
quickly dissipated like a pack of killer rabbits on a Holy Knight trail
when I read the paper. The paper describes the first successful rearing
of the yellow tail damselfish, Chrysiptera parasema. I am not
sure how this relates to the secrets of each species, since they only
bred the one species, but fear not, read on.
The
researchers set up four breeding pairs of damsels that had been
purchased at a local pet store in Bergamo, Italy, by buying eight
damsels and placing them in the same 120 liter tank. Once they began to
pair up they removed each pair to their own 80 liter tank. Spawning
began approximately three months after the pairs were placed in their
own tanks. The tanks were kept at 28 oC, salinity of 30 ppt and with a
photoperiod of 13 hours of light and 11 hours of darkness (13:11).
The
males construct a nest under a rock and then entice the female inside
where she deposits several hundred eggs. After 7 days the rock with the
eggs attached were moved to hatching bucket and within two hours of
darkness the eggs began to hatch and then were moved to the rearing
tanks. Rearing tanks consisted of 25 liter tanks with water that was
neither filtered nor aerated since the larvae are very delicate and very
sensitive to any turbulence. The sides of the tank are covered so that
light can only enter from above. Chlorella and Isochrysis
algae were added to tank such that the bottom of the tank was no longer
visible. Approximately 15% of the water was changed every day and two to
three drops of a 5% potassium iodide solution was added twice a day to
help with metamorphosis. Eggs batched were divided into different groups
so that the affect of different photoperiods could be evaluated. Three
different photoperiods were used 13:11, 16:8 and 24:0 to raise various
replicate groups of larvae.
The
larvae still have yolk sacs at hatching but these are consumed within 24
hours so a first food must be introduced soon after hatching or the
larvae will quickly starve. The first food used was the common rotifer Brachionus
plicatilis at a density of 20 rotifers per mL, any greater density
resulted in larval die-off due to reduced oxygen levels. Rotifers were
enriched using Selcon per manufacture’s recommendations. At day 19
from hatching, a second food was used, live, newly hatched Artemia
at a density of 5 nauplii/mL, from INVE technologies in Belgium. These
commercial decapsulated brine shrimp cysts are already enriched by the
company with HUFAs (highly unsaturated fatty acids).
The
results showed a marked difference in survival between
the different photoperiods. Those larvae fed
unenriched foods lasted only 48 hours. Those fed
enriched rotifers under a photoperiod of 13:11 died
within 3 days. Those under the 16:8 photoperiod died
after 7 days and those under the 24:0 photoperiod
survived until settlement at day 17 with a survival
rate of 25%. The 24 hour light group not only survived
better but grew faster as well. The increased survival
under a 24 hours light régime has also been noted for
black porhy, gilthead seabream and rabbitfish.
However, other fish species have been reported to have
better success under 16 or 18-hour régimes. This
points out the need to assess the importance of
photoperiod for each genus of fish that you are trying
to breed.
Ishi
B. I. and K. J. McGlathery. 2003. Effect of
ultraviolet light on dissolved nitrogen
transformations in coastal lagoon water. Limnology
and Oceanography 48(2):723–734.
This study
looked at the effect of ultraviolet radiation on the
production of inorganic nitrogen, urea, and amino
acids from aquatic dissolved organic matter (DOM) in
the waters from Hog Island Bay, a coastal lagoon in
Virginia. Samples from distinct sources of DOM to the
lagoon were subjected to UV light mimicking the
natural solar spectrum. It was found that dissolved
organic nitrogen concentrations did not change
measurably during the 36-h incubation, while
calculated dissolved organic carbon concentrations
dropped by up to 17%. Nitrate and urea levels were not
consistently altered in the light, while ammonium
photoproduction rates of up to 0.032 µmol N L-1 h-1
were observed. However, it was felt that the rates of
ammonium and amino acid formation, when scaled up to
estimate photoproduction in the lagoon system,
appeared to be minor relative to other sources to and
fluxes within the lagoon. What was of greatest
interest to me about this study was that the
calculated dissolved organic carbon (DOC)
concentrations dropped by up to 17%. Activated carbon
is often used in aquaria for removing DOC’s but it
is also possible to reduce the level of DOC using
ultraviolet light and ozone. The combined use of UV
(or ozone) and carbon may prolong the useful life of
activated carbon or other products that remove DOCs.
Proud
sponsor of this column
Recent
Publications
Anemones
Acuna,
F.H., Excoffon, A.C., Zamponi, M.O. and L. Ricci. 2003. Importance of
nematocysts in taxonomy of acontarian sea anemones (Cnidaria, Actinaria).
A statistical comparative study. Zoologischer Anzeiger 242(1):75-82.
Cephalopods
Kier,
W.M. and A.M. Smith. 2002. The structure and adhesive mechanisms of
octopus suckers. Integrative and Comparative Biology 46(6):1146-1153.
Corals
Anthony,
K.R.N. and O. HoeghGuldberg. 2002. Variation in coral photosynthesis,
respiration and growth characteristics in contrasting light
microhabitats: an analogue to plants in forest gaps and understoreys? Functional
Ecology 17(2):241-259.
Bhagooli,
R. and M. Hidaka. 2003. Comparison of stress susceptibility of in
hospite and isolated zooxanthellae among five coral species. Journal
of Experimental Marine Biology and Ecology 291(2):181-198.
Brooke,
S. and C.M. Young. 2003. Reproductive ecology of a deep-water
scleractinian coral Oculina varicosa from the southeast Florida
shelf. Continental Shelf Research 23(9):847-858.
Bongiorni,
L., Shafir, S., Angel, P. and B. Rinkevich. 2003. Survival, growth, and
gonad development of two hermatypic corals subjected to in situ
fish-farm nutrient enrichment. Marine Ecology Progressive Series
253:137-145.
Clode,
P.L. and A.T. Marshall. 2003. Variation in skeletal microstructure of
the coral Galaxea fasicularis: effects of an aquarium environment
and preparatory techniques. Biological Bulletin 204(2):138-145.
Clode,
P.L. and A.T. Marshall. 2003. Skeletal microstructure of Galaxea
fasicularis export septa: A high resolution SEM study. Biological
Bulletin 204(2):146-158.
Goulet,
T.L. and M.A. Coffroth. 2003. Stability of an octocoral-algal symbiosis
over time and space. Marine Ecology Progressive
Series 250:117-124.
Harriott,
V.J. 2003. Can corals be harvested sustainably? AMBIO 32(2):130-133.
Kerswell,
A.P. and R.J. Jones. 2003. Effects of hypo-osmosis on the coral Stylophora
pistillata: nature and cause of “low salinity bleaching”. Marine
Ecology Progressive Series 252:145-154.
Miller,
S.W., Hayward, D.C., Bunch, T.A., Miller, P.J., Bull, E.E., Bardwell,
V.J., Zarkower, D. and D.L. Bauer. 2003. A DM domain protein from a
coral Acropora millepora, homologous to proteins important from
sex determination. Evolution and Development 5(3):251-259.
Orejas,
C., Gili, J.M. and W. Arntz. 2003. Role of small plankton communities in
the diet of two Antarctic octocorals (Primnoisis antarctica and Primnoella
sp.). Marine Ecology Progressive Series 250:105-116.
Stillman,
J.H. 2003. Sunny side up for hot corals. Journal of Experimental
Biology 206(9):1435-1436.
Diseases
Farto,
R., Armada, S.P., Montes, M., Guisande, J.A., Pereze, M.J. and T.P.
Nieto. Vibrio lentus associated with diseased wild octopus (Octopus
vulgaris). Journal of Invertebrate Pathology 83(2):149-156.
Pantos,
O., Cooney, R.P., LeTessier, M.D.A., Barer, M.R., O’Donnell, A.G. and
J.C. Bythell. 2003. The bacterial ecology of a plaque-like disease
affecting the Caribbean coral Montastrea annularis. Environmental
Microbiology 5(5):370-382.
Yambot,
A.V., Jong, Y.L. and H.H. Sung. 2003. Characterizations of Cryptocaryon
irritans, a parasite isolated from marine fishes in Taiwan. Diseases
of Aquatic Organisms 54(2):147-156.
Filtration
Bomo,
A.M., Husby, A., Stevik, T.K. and J.F. Hanssen. 2003. Removal of fish
pathogenic bacteria in biological sand filters. Water Research
37(11):2618-2626.
Chen,
Y.H., Chang, C.Y., Chiu, C.Y., Yu, Y.H., Chian, P.C., Ku, Y. and J.N.
Chen. 2003. Dynamic behaviour of ozonation with pollutant in a counter
current bubble column with oxygen mass transfer. Water Research
37(11):2583-2594.
Du,
G.C., Geng, J.J., Chen, J. and S.Y. Lun. 2003. Mixed culture of
nitrifying and denitrifying bacteria for simultaneous nitrification and
denitrification. World Journal of Microbiology and Biotechnology
19(4):433-438.
Fishes
Asoh,
K. and T. Yoshikawa. 2003. Gonadal development and an indication of
functional protogeny in the Indian damselfish (Dascyllus carneus).
Journal of Zoology 260(1):23-40.
Cohen,
P.J. and D.A. Ritz. 2003. Role of kairomones in feeding interactions
between seahorses and mysids. Journal of the Marine Biological
Association of the U.K. 83(3):633-638.
Cote,
I.M. and P.P. Molloy. 2003. Temporal variation in cleanerfish and client
behaviour: Does it reflect ectoparasite availability? Ethology
14:487-500.
Harding,
JA., Almany, G.R., Houch, L.D. and M.A. Hixon. 2003. Experimental
analysis of monogamy in the Caribbean cleaner goby, Gobiosoma
evelynae. Animal Behaviour 65(5):865-874.
Hilder,
M.L. amnd N.W. Pankhurst. 2003. Evidence that temperature change cues
reproductive development in the spiny damselfish Acanthochromis
polycanthus. Environmental Biology of Fishes 66(2):187-196.
Leis,
J.M. and B.M. Caron-Ewart. 2003. Orientation of pelagic larvae of
coral-reef fishes in the ocean. Marine Ecology Progressive Series
252:239-254.
Payne,
A.G., Smith, C. and A.C. Campbell. 2003. Interactions between ophiuroids
and beaugregory damselfish. Journal of the Marine Biological
Association of the U.K. 83(3):625-632.
Southall,
E.J., Merrett, D.A. and S. Saunders. 2003. Effects of zooplankton
density and diel period on surface-swimming duration of basking sharks. Journal
of the Marine Biological Association of the U.K. 83(3):643-446.
Trotter,
A.J., Pankhurst, P.M., Morehead, D.T. and S.C. Battaglene. 2003. Effects
of temperature on initial swim bladder inflation and related development
in cultured striped trumpeter (Latris lineata) larvae. Aquaculture
221(104):141-156.
Trotter,
A.J., Battaglene, S.C. and P.M. Pankhurst. 2003. Effects of photoperiod
and light intensity on initial swim bladder inflation, growth and
post-inflation viability in cultured striped trumpeter (Latris
lineata) larvae. Aquacultre 224(1-4):141-158.
General
Nash,
R. and B.F. Keegon. 2003. Aspects of the feeding biology of the fanworm Bispira
volutacornis (Polychaete: Sabellidae). Journal of the Marine
Biological Association of the U.K. 83(3):453-456.
Shine,
R., Coggers, H.G., Reed, R.R., Shetty, S. and X. Bonnet. 2003. Aquatic
and terrestrial locomotor speeds of amphibious sea-snakes (Serpentes,
Laticaudidae). Journal of Zoology 259(3):261-268.
Smith,
A.M. 2002. The structure and function of adhesive gels from
invertebrates. Integrative and Comparative Biology 46(6):1164-1171.
Giant Clams
Hean,
R.L. and O.J. Cacho. 2003. A growth model for giant clams Tridacna
crocea and T. derasa. Ecological Modeling 163(1-2):87-100.
This
special issue of the journal Aquaculture, contains 37 published papers
on fish nutrition that were presented at the 10th
International Symposium on Nutrition and Feeding in Fish, held in June
2002 on the Greek island of Rhodes. Papers are divided into the
following categories: Feedstuff/Diet Evaluation, Lipids and Fatty Acids,
Vitamins and Minerals, and Larval Nutrition. The 37 published papers
represent those of most interest to the participants; there were over
250 papers presented.
Castell,
J., Blair, T., neil, S., Hawes, K., Mercer, S., Reid, J., Young Lai, W.,
Gullison, B., Dhert, P. and P. Sorgeloos. 2003. The effect of different
HUFA enrichment emulsions on the nutritional value of rotifers fed to
larval haddock Metamogrammus aeglefinius. Aquaculture
International 11(1-2):109-118.
Mitra,
G. amd P.K. Mukhopadhyay. 2003. Dietary essentiality of ascorbic acid in
rohu larvae: Quantification with ascorbic acid enriched zooplankton. Aquaculture
International 11(1-2):81-94.
Monroig, O.,
Navarro, J.C., Amat, I., Gonzalez, P., Amat, F. and F. Hontoria. 2003.
Enrichment of Artemia nauplii in PUFA, phospholipids and
water-soluble nutrients using liposomes. Aquaculture International
11(1-2):151-162.
Seagrasses
Duffy,
J.E., Richardson, J.P. and E.A. Convel. 2003. Grazer diversity effects
on ecosystem function in seagrass beds. Ecology Letters 6(7).637-646.
Heck,
K.L., Hays, G. and R.J. Orth. 2003. Critical evaluation of the nursery
role hypothesis for seagrass meadows. Marine Ecology Progressive
Series 253:123-136.
