My project page is being updated, the following is
from the past few years:
I have worked on a wide variety of topics in reef fish
biology. My dissertation was on the population biology
of a coral reef wrasse, but I have since concentrated
on larval fishes and collected and catalogued tens of
thousands of fish larvae in the open ocean as well as
on the reef. In addition, I discovered two new species
of razorfishes in the Galapagos Islands and studied
behavioral ecology and mating systems in the Caribbean.
My recent projects primarily focus on exploring the
role larval ecology plays on the population biology,
genetics, and biogeography of coral reef fishes. Virtually
all coral reef fishes have a larval stage that lives
in the open ocean for weeks or months before settling
onto a reef. Since so much of the life of coral reef
fish larvae is completely unknown, it is an interesting
and challenging pursuit. I particularly like the detective
work and deduction required to infer what is happening
in the plankton from the few glimpses we have into the
hidden life of fish larvae. Essentially all I have to
work with is my collections of larvae from the plankton
and, fortunately, a very serendipitous phenomenon- the
formation of daily rings on the otoliths of these fishes.
Otoliths are calcium carbonate accretions (stones) in
the ears of fishes used for balance and hearing. The
otolith of bony fishes grows by adding increments to
the surface each day, like an onion, leaving alternating
dark and light lines which closely resemble tree rings.
Often these increments are laid down each day and transitions
can be detected which correspond to hatching, settlement,
and other life history events. These daily increments
are incredibly valuable as a record of age, previous
growth, and even the chemistry of the environment to
which the larva had been exposed. I helped pioneer this
powerful new aging technique in the 1970s and 1980s,
and have been using otoliths since then to explore all
kinds of questions about the life of reef fish larvae.
I trained at the University of California at Santa Barbara,
known to be a hotbed of rigorous hypothesis testing.
However, larval fishes living out in the open waters
are not the most conducive subjects for this form of
research. The Santa Barbara philosophy is very well-suited
to barnacles and algae and other more "tangible"
organisms and systems and I wholeheartedly endorse it.
Yet, my research is more exploratory and "phenomenological".
While this approach is less "exact" than the
usual rigorous methodological approach to scientific
questions, i.e. erect an hypothesis and go out and measure
the quantities required to accept or reject the hypothesis,
it is more intriguing. I do admire and promote rigorous
approaches, yet these just aren't that easy for this
line of research. There are a number of biologists who
are hewing to the line and testing hypotheses on the
life of larval reef fishes (at AIMS and the Australian
Museum) and I highly recommend their work. However,
I prefer to ask more general questions and deduce what
may be going on by assembling pieces of a puzzle. I
particularly like the idea that each fact discovered
narrows down the world of possible phenomena and can
be used to reject a proposed model and encourage an
alternative. While it doesn't build a correct
model, it is, in essence, a process of elimination spiralling
around the true model, and, in my opinion, a lot more
fun and adventure- rather like a detective instead of
a watchmaker....
I have a variety of projects currently, often slowly,
underway in My first project in this area is on the
pelagic larval duration (PLD) of the rainbow wrasse,
Thalassoma lucasanum. I have been studying the
early life history of this very common fish for many
years with Jerry Wellington (formerly at the University
of Houston). We discovered that there is a large seasonal
difference in the PLD of this fish and some others in
Baja. This is particularly unusual, since reef fish
larvae generally have little temporal variation in PLD,
at least much less than the huge differences we found,
which ranged from 40 to 120 days from one season to
another. Given that so little is known about where fish
larvae go and what they do there, this anomaly may provide
some very useful hints. Finding this focus of extreme
variation allows a set of interesting questions to be
asked: what causes the difference? are the larvae coming
from different places? do they grow at different rates
or just stay longer and grow larger in the plankton
in different seasons? is this pattern uniform or variable
along the coast of Baja California? does the variation
track changes in water temperature or current regimes?
Is the microchemistry different? We also found that
El Nino exaggerated the pattern: during the El Nino
PLDs were very short, and during La Nina PLDs were exceptionally
long. Clearly this site and this species are an excellent
case study of sources of variation in larval duration.
A second study in Baja concerned the effects of very
short and very long larval lives on population genetics
and biogeography. This research was in collaboration
with Cynthia Riginos (U. Queensland) and building on
the work of Mike Brogan in Baja. We studied the small
blennies in the Sea of Cortez because this group of
fishes, unlike most others, displays a very wide variety
of larval strategies- from extremely short larval durations
and a strictly inshore distribution of larvae in the
triplefins (such as Axoclinus nigrocaudus) to
long larval durations and offshore larval distributions
in the Panamic fanged blenny, Ophioblennius steindachneri.
Our findings (see publications) show an impressive difference
in genetic heterogeneity (genetic population "structure")
between the two species: triplefins are clearly genetically
different between sites, even within the Sea of Cortez,
indicating essentially closed populations with larvae
remaining in the local area, while the blenny has no
apparent genetic differences between populations we
sampled. This is one of the first clear documentations
of the effect of larval ecology on genetic population
structure in reef fishes. Other projects I am doing
in Baja include general collections and identifications
of reef fish larvae and collaborations on the population
ecology of the snappers in the region Galapagos Islands
The Galapagos Islands are a very interesting place
to work, although the fishes are not nearly as exotic
as the more famous tortoises, iguanas, penguins and
finches of these islands. There are many endemic fish
species as well as a combination of warm-water tropical
fauna and cold-water Peruvian province species in the
southern and western islands. In addition, the Galapagos
Islands are at the epicenter of the El-Nino Southern
Oscillation (ENSO) event that affects world-wide weather
systems and has important effects on marine life in
the tropics, especially in the eastern Pacific region.
Recently, we assembled the observations of reef fish
biologists in the region, including Jerry Wellington
(ex-University of Houston), Ross Robertson (Smithsonian
Tropical Research Institute in Panama) and Benjamin
Ruttenberg (University of California, Santa Barbara)
to assess the impact of the massive 1997-1998 ENSO on
reef fishes, especially the wrasse family that I have
been surveying for many years. We found that the labrid
reef fishes appeared to do well during the ENSO, with
heavy recruitment noted for most species. The most notable
finding was the arrival of a species previously rare
in the Galapagos, Stethojulis bandanensis. I
found numerous newly-recruited juveniles in many places
in the islands at the end of the ENSO in 1998. Interestingly,
they had a relatively short pelagic larval duration,
only about 30 days, so if they had originated elsewhere
they had traveled very fast. Since it is very unlikely
they originated from the Galapagos, the nearest source
population would be Cocos Island, many hundreds of miles
away. In other words, there must have been some rapid
long-distance dispersal for these larvae- a phenomenon
not easily documented for reef fishes..
My first research project in the islands was a survey
of the pelagic larval duration of the labrids (wrasse
family). During the visit I discovered a new species
of razorfish unknown to science. Razorfishes are a sub-group
of wrasses that live on sandbeds and dive into the sand
when disturbed. As a result, their bodies are very narrow
and their head ends in a sharp keel (the "razor")
allowing them to swim through the sand. This new species
had eluded the previous zoologists that had collected
fishes in the islands, starting with Charles Darwin
(in the age before masks and snorkels, fishing was the
only way to collect fish) up to the present. The reason
was probably that razorfishes live on open expanses
of sand and most biologists naturally gravitate to the
more interesting reefs. Also, this species congregates
in large colonies in particular places- making it a
matter of luck whether one explores that particular
area. Fortunately, I stumbled into a large colony of
these fishes on a dive on the island of Marchena and,
realizing these were an unknown species, collected many
of them with a small spear. Needless to say, it was
one of the more exciting days of my life. The fish,
since named Xyrichtys victori, is a spectacularly
colored fish: the females are bright orange and the
males are iridescent blue-green with prominent black
blotches that vary from individual to individual. Variation
in markings to this degree from one fish to the next
is very rare among reef fishes, and perhaps evolved
in this species to permit individual recognition of
displaying males, since it occurs only in the male of
the species. Since then I have collected two forms of
juvenile razorfishes, one of which is morphologically
unusual, and must represent a new species. I plan to
run some DNA sequence analyses to see where that razorfish
places among the known species in the region.
History: I did most of my early research in
the Caribbean during the 1980s. My dissertation was
on the population biology of reef fishes, in particular,
the bluehead wrasse, Thalassoma bifasciatum.
In those days there was little interest in younger fishes,
which were considered mostly food for the older ones.
The traditional view of ecosystems was concerned with
carrying capacities and the factors controlling the
numbers of adults observed (and ecology was a relatively
new science, which only really got going in the sixties).
Typically, from experience with terrestrial biology,
the important factors were predation and competition-
with a bit of physical factors thrown in. The advent
of scuba and a developing interest in the tropics encouraged
the new wave of young academic ecologists to start to
look at coral reefs in a similar manner, and, very quickly,
they began to find that reefs were not so simple. Interest
in the role of larval settlement was first sparked by
Peter Sale among the (few) tropical marine fish biologists
at the time. Indeed, in May 1976, there was a mini-symposium
at Cornell University on the role of recruitment in
the ecology of reef fishes, where Peter Sale started
some arguments that still continue today. By pure coincidence,
I was a sophomore taking the ichthyology class next
door, blissfully unaware of the existence of any controversies
on palm-studded islands far away (I was pushing sheets
of ice out of the way in pursuit of freshwater stream
fishes at that time). My research project after ichthyology
class was to use otoliths to age some fishes in the
streams around Ithaca, New York. Ed Brothers, who was
working on otoliths after studying the life history
of gobies at Scripps in San Diego, had just started
as a professor at Cornell, and he taught me how to look
at daily otolith increments. After doing a project on
the age and growth of a freshwater cyprinid fish, I
was ready for some warmer weather and applied to Hawaii,
Florida, and Santa Barbara for graduate school. I went
to UC Santa Barbara where Bob Warner was studying the
behavioral ecology of the bluehead wrasse, and then
spent some years at Bob's research site in the San Blas
Islands of Panama. Daily otolith increments happened
to be ideal for studying the early life history of reef
fishes, and I started to collect data on the settlement
patterns and the age and growth of larval and juvenile
bluehead wrasse. After many years I have returned to
my larval collections I made for several years in the
mid-1980s in the San Blas Islands of Panama. Unfortunately,
I had spent hundreds of hours making ink drawings of
the larvae, and now the web and digital photography
have essentially rendered drawings old-fashioned, and
I have now begun to photograph all of my larvae. As
one can imagine, this is a gigantic job, since there
are perhaps a thousand species of reef or reef-associated
fishes in the Caribbean. I started with the gobies,
since they account for well over a hundred of these
species and I like a challenge. Thus far, I have identified
and photographed almost all of the shallow-water gobioid
genera, and I am beginning to photograph other families
of fishes. After that I can move on to my eastern Pacific
collections and even the large collection of larvae
I have from Rangiroa, in French Polynesia. But, the
Indo-Pacific is daunting- since the number of species
goes up exponentially, and I depend on the process of
elimination, to a large degree. By the time I get to
those larvae, molecular techniques, such as dna fingerprinting
or barcoding, will likely be the method of choice for
identifying larvae to species.