Frederick W. Harrison

Paleoecology of central Kentucky since the last glacial maximum

Pollen grains and spores, plant macrofossils, and sponge spicules from a 7.2-m sediment core from Jackson Pond dating back to 20,000 yr B.P. are the basis for new interpretations of vegetational, limnological, and climatic changes in central Kentucky. During the full-glacial interval (20,400 to 16,800 yr B.P.) upland vegetation was closed spruce forest with jack pine as a subdominant. Aquatic macrophyte and sponge assemblages indicate that the site was a relatively deep, open pond with low organic productivity. During late-glacial time (16,800 to 11,300 yr B.P.) spruce populations continued to dominate while jack pine declined and sedge increased as the vegetation became a more open, taiga-like boreal woodland. Between 11,300 and 10,000 yr B.P., abundances of spruce and oak pollen oscillated reciprocally, possibly reflecting the Younger Dryas oscillation as boreal taxa underwent a series of declines and increases at the southern limit of their ranges before becoming extirpated and replaced by deciduous forest. In the early Holocene (10,000 to 7300 yr B.P.) a mesic deciduous woodland developed; it was replaced by xeric oak-hickory forest during the middle Holocene between 7300 and 3900 yr B.P. Grass increased after 3900 yr B.P., indicating that the presettlement vegetation mosaic of mixed deciduous forest and prairie (the “Kentucky Barrens”) became established in central Kentucky after the Hypsithermal interval. Sponge spicules increased in number during the Holocene, reflecting reduced water depths in the pond. Sediment infilling, as well as climatic warming and the expansion of fringing shrub thickets, increased nutrient and habitat availability for freshwater sponges.

Utilization of freshwater sponges in paleolimnological studies

Abstract Prior to the past decade, freshwater sponges had not been utilized in paleolimnological studies. There were valid reasons for this: the taxonomy of the spongillid freshwater sponges of the world was in complete disarray; the ecological parameters of freshwater sponge species either were not known or were presented in scattered publications that were not readily available to paleolimnologists. The revisionary work of Penney and Racek finally brought order into the chaos of spongillid systematics. Shortly after the appearance of the Penney-Racek landmark monograph, Poirrier, and later Harrison, described the ecological parameters of North American spongillid freshwater sponges in a series of species-by-species treatments. Racek, in a body of pioneering studies, evaluated spicular remains of freshwater sponges in cores dating to 30,000 yr B.P. from several lakes, i.e., Lake Huleh, Lago di Monterosi, Laguna de Petenxil, while Harrison and colleagues characterized the past history of Lake Okeechobee (3000–4000 yr B.P.) and of Serendipity Bog, Graham Island, British Columbia (9400-8500 yr B.P.) using spicular components. It is now evident that freshwater sponge skeletal and reproductive structures can be used to characterize accurately past ecological conditions of freshwater habitats. In this paper, I will introduce the reader to the pertinent literature in freshwater sponge taxonomy, will characterize spongillid species into broad groups based upon their environmental parameters, and will summarize present paleolimnological studies using freshwater sponge remains as a diagnostic tool.

Structure and cytochemistry of the silk glands of the mygalomorph spider Antrodiaetus unicolor (araneae, antrodiaetidae)

Dissection and a variety of absorption and fluorescent cytochemical methods have demonstrated that Antrodiaetus unicolor females have only one type of silk gland and spigot and, consequently, the simplest silk production system of any spider yet investigated histochemically. The small spherical to pear‐shaped glands are grouped into four clusters, each cluster serving one of the four spinnerets. The spigots are long, slender, and slightly bent distally. Although all gland cells are structurally similar, each gland simultaneously produces two different secretory products, the secretion of the distal hemisphere being rich in basic protein and sulfhydryl groups, and the proximal hemisphere secretion being an acidic protein containing a high concentration of histochemically demonstrable C‐terminal carboxyl groups. The two products remain segregated as they pass through the duct, where the acidic protein forms a thin outer layer around a core of basic protein. It is suggested that this segregation may persist in the silk strand after it exits from the spigot and that the outer acidic protein may be an adhesive agent.

The taxonomic and ecological status of the environmentally restricted Spongillid species of North America. V. Ephydatia subtilis (Weltner) and Stratospongilla penneyi sp. nov.

The taxonomic status of Ephydatia subtilis (Weltner) remains undetermined. Despite extensive collecting in the type locality, Lake Kissimmee, Florida, the species was not found. Stratospongilla penneyi sp. nov. is described utilizing spicular diagnosis, cytochemistry, and scanning electron microscopy. Physicochemical data from the type locality are presented and specific threats to the existence of the species are determined.

The taxonomic and ecological status of the environmentally restricted spongillid species of North America. III. Corvomeyenia carolinensis Harrison 1971

The taxonomic validity, present distribution, and specific threats to the existence of the freshwater sponge, Corvomeyenia carolinensis Harrison 1971 were investigated. This species, a valid environmentally restricted species, has not colonized other areas beyond the type locality, Adams Pond, Richland County, South Carolina. At present, the only threat to the existence of this species is the aggressive competition for substrate provided by Heteromeyenia baileyi, a sponge species recently colonizing the habitat. Habitat data, particularly physicochemical data, from Adams Pond and other components of the Mill Creek drainage system greatly extend the known environmental parameters of Corvomeyenia carolinensis, Heteromeyenia baileyi, Anheteromeyenia ryderi, Spongilla lacustris, and Trochospongilla pennsylvanica.

Cytological and cytochemical investigations of development from dormant gemmules of the marine sponge, Haliclona loosanoffi

Vernalized gemmules of the marine sponge Haliclona loosanoffi were cultured at 20°C, fixed at 24‐hour intervals (0–11 days), and processed for light microscopy by using a variety of absorption and fluorescent staining methods. The cytochemistry and morphology of development were compared to the well‐studied developmental patterns of freshwater sponges and to the patterns described in the marine sponge Suberites domuncula. The precocious development of H. loosanoffi gemmules involves early morphogenesis occurring within the unhatched gemmule, as opposed to the patterns in freshwater sponges, where most development occurs after the gemmule hatches. Definitive sponge tissue surrounding a single osculum is present 9 days after release from dormancy.

The taxonomic and ecological status of the environmentally restricted spongillid species of North America. IV. Spongilla heterosclerifera Smith 1918

The taxonomic status, present distribution and specific threats to the existence of the environmentally restricted freshwater sponge, Spongilla heterosclerifera Smith 1918 were investigated. This species, collected only from Oneida Lake, New York, has not colonized other habitats and continues to exhibit typical diagnostic characteristics, thus qualifying as a valid environmentally restricted species. Although the sponge presently colonizes two sites in the lake, both near the northwestern shore, the total absence of sponge fauna from other lake regions near more heavily populated areas of this species. Physicochemical data from Oneida Lake greatly extend the known environmental parameters of Spongilla heterosclerifera.

Scanning electron microscopy of taxonomic diagnostic criteria of the freshwater sponge, Heteromeyenia tubisperma (Potts, 1881) (Porifera : Spongillidae)

Taxonomic diagnostic criteria of the spongillid freshwater sponge, Heteromeyenia tubisperma (Potts, 1881) were examined using scanning electron microscopy. The species is characterized by a gemmule which bears an unusually long, prominent porous tube. The application of SEM to the systematic studies of the freshwater sponges provides diagnostic capabilities not available with the light microscope. It is desirable that a key, coupled with a reference atlas of scanning electron micrographs illustrating taxonomic diagnostic criteria of freshwater sponge species, particularly utilizing type specimens, be developed.