Dobkin, Sheldon

This paper presents data relative to the ecology and
bathymetric distribution of hermatypic gorgonians. The
reefs were analyzed with respect to faunal composition and
zonation. Ecological data such as turbidity, light penetration,
salinity, dissolved oxygen and temperature were
taken directly on the reefs. The main reef was carbondated
(C^14 ) to determine the length of time required for
development. Gorgonians were transplanted from 9 meters
to 18 and 30 meters to observe growth rates and spicule
changes. The relationships of zooxanthellae to the hermatypic
Gorgonacea were analyzed and discussed. Experiments
were conducted concerning respiration and photosynthetic
rates, minimum oxygen tolerance, compensation intensities
and depth, and starvation in the light as well as in the
dark. Tolerance limits were establIshed for various levels
of salinity, and temperature. Feeding behavior experiments
were recorded and the relationship of gorgonian populations
to the reef structure and community were discussed.

Many marine organisms possess endosymbiotic dinoflagellates called zooxanthellae. Bleaching is the loss of zooxanthellae, but bleached hosts can be repopulated. Little is known about how repopulation is controlled. The sea anemone Aiptasia pallida was used to study the effects of feeding on repopulation. Two groups of aposymbiotic anemones were reinfected with algae from symbiotic clones. One group was fed and the other starved, and counts of algae within each anemone were made at 3 day intervals for 6 weeks. The experiment was repeated, and results showed that the rate of algal growth did not differ between fed and starved groups. However, starved anemones reached plateau more quickly and lost algal cells after plateau was reached, whereas fed anemones contained more algae and protein. This suggests that starved anemones can support an algal population initially, but cannot maintain it. Space and nutrients are implicated in having a limiting effect on maintenance of symbionts.

The grass shrimp, Palaemonetes paludosus, was studied during a two year period from a population in southern Florida. The shrimp exhibited significant deviations from an expected sex ratio of 1:1 in certain size classes. Males were found more frequently in small to intermediate size classes while females dominated the largest size classes. Recruitment was continuous and ovigerous females were found year-round. Clutch size increased with increasing carapace length of the shrimp. A differential growth rate may account for the variations in sex ratio among different size classes found in this shrimp.

The xanthid crabs Eurypanopeus depressus and E. dissimilis co-occur among oysters on seawalls in southeastern Florida. Population dynamics and aspects of the life history of these two species were compared during a 1-year period, at two study sites. There were no interspecific differences in adult size for either sex. For both species, females were significantly more abundant than males. E. depressus was more abundant at one study site, E. dissimilis at the other. Ovigerous females were found year-round. Number of eggs per female of both species increased with increasing carapace width. Recruitment of young into the population occurred year-round.

Leander tenuicornis (Say) and Latreutes fucorum (Fabricius) are two
caridean shrimps abundant on floating sargassum. The ovigerous females
were captured offshore of Dade and Broward Counties in southern Florida.
Larvae were reared in a recirculating system and in plastic compartmented
trays in sea water of 35 parts per thousand at 24-30°C. The larval
development of Latreutes fucorum is comprised of nine morphological stages
and has a duration between 18 and 30 days in the laboratory. Larval and
postlarval stages of this species are described. The larval development
of Leander tenuicornis is comprised of eight morphological stages. These
are described and compared to larvae of other members of the genus
descr-ibed as well as other previously described specimens of L. tenuicornis.
Distinctions between larvae of L. tenuicornis and those of other
members of the genus in addition to peculiarities shown by the adult, are
sufficient to suggest the erection of a new genus to include this form.