John A. Fornshell

Causation of large-amplitude coastal seiches on the Caribbean coast of Puerto Rico

Abstract Sea-level oscillations at supertidal frequency with amplitudes of the order of the mean tidal range have been reported from the Caribbean coast of Puerto Rico. Analysis of a 10-year time series of digital tide data from Magueyes Island, Puerto Rico, demonstrates that sea-level variance at the fundamental normal mode (sciche) frequency of the shelf has a pronounced fortnightly distribution with a maximum occurring 6–7 days after new and full moon. The sieche variance also shows a bimodal seasonal distribution with an inverse relationship to easterly wind stress. It is argued that the sciches are excited by internal waves generated by strong tides in the southeastern Caribbean. Support is provided by airborne radar imagery showing sea-surface patterns suggesting the presence of internal waves near the southern Aves Ridge, and by the results of two field experiments, carried out during times when large-amplitude sciches were expected, to search for evidence of internal wave forcing near the shelf br...

Early Post-Embryonic Development of Marine Chelicerates and Crustaceans with a Nauplius

Crustaceans that hatch as a nauplius-like larva, as well as xiphosuran and pantopodan chelicerates, are surveyed for five characters: presence or absence of arthrodial membranes separating somites; ventral configuration of the protopod of the second limb; number of transformed (segmented) limbs and limb buds; addition of segments to transformed limbs; fate of limb buds. An arthrodial membrane separates somites 7 and 8 of xiphosurans, a small knob articulates on the protopod of the second limb, and there are nine pairs of limbs but no limb buds. During early development, no arthrodial membranes are added, nor are segments added to limbs 1-9; limbs 10-14 are added as transformed limbs, not as limb buds, after several molts. On the post-embryonic larva of the presumed ancestral pantopodan, arthrodial membranes did not separate adjacent somites, the proximal segment of limb 2 was simple, there were three transformed limbs and no limbs buds. During subsequent molts, arthrodial membranes separated somites 4-7, buds of limbs 4-7 were added in register with each molt, limb buds were reorganized in register into transformed limbs during the following molt, and two segments were added to each transformed limb in register during the next molt. Somites of most crustacean taxa that hatch as a nauplius-like larva are not separated by arthrodial membranes on early post-embryonic stages; exceptions are posterior somites of branchiurans, mystacocaridans and cephalocaridans. Limb 2 (antenna 2) of branchiopods, copepods, thecostracans, mystacocaridans and cephalocaridans bears a naupliar arthrite on the ventral face of the coxa, on branchiurans there is an attenuation, or spine-like outgrowth, on the ventral face, and on 5) Corresponding author; e-mail: ferrarif@si.edu 6) e-mail: johnfornshell@hotmail.com 7) e-mail: avagelli@njaas.org 8) e-mail: ivanenko@mail.bio.msu.ru 9) Co-corresponding author; e-mail: hansdahms@smu.ac.kr

The Development of SONAR as a Tool in Marine Biological Research in the Twentieth Century

The development of acoustic methods for measuring depths and ranges in the ocean environment began in the second decade of the twentieth century. The two world wars and the “Cold War” produced three eras of rapid technological development in the field of acoustic oceanography. By the mid-1920s, researchers had identified echoes from fish, Gadus morhua, in the traces from their echo sounders. The first tank experiments establishing the basics for detection of fish were performed in 1928. Through the 1930s, the use of SONAR as a means of locating schools of fish was developed. The end of World War II was quickly followed by the advent of using SONAR to track and hunt whales in the Southern Ocean and the marketing of commercial fish finding SONARs for use by commercial fisherman. The “deep scattering layer” composed of invertebrates and fish was discovered in the late 1940s on the echo sounder records. SONARs employing high frequencies, broadband, split beam, and multiple frequencies were developed as methods for the detection, quantification and identification of fish and invertebrates. The study of fish behavior has seen some use of passive acoustic techniques. Advancements in computer technology have been important throughout the last four decades of the twentieth century.

Anticyclonic Eddy Observations in the Slope Water Aboard CGC Evergreen

Abstract An anticyclonic eddy was surveyed twice, once in late September and again two months later in early December by the CGC Evergreen. The two surveys involved a total of 25 CTD stations, 184 XBTs and two subsurface drogued buoys for direct current measurements during the December cruise. The eddy was tracked with infrared satellite imagery from 2 September 1977 to 24 January 1978. In the two-month period between the first and second cruises the horizontal extent of the eddy, defined by the juncture of the 15°C isotherm with the 200 m isobath, decreased from 185 to 148 km. The baroclinic currents extended to a depth of at least 3000 m in late September and to a depth of only 1600 m two months later in December. The available potential energy referenced to 1600 m decreased from 75 × 1015 to 32 × 1015 J in the same period. The maximum baroclinic currents decreased from 103 to 73 cm s−1. Direct current measurements in early December with subsurface drogued buoys showed currents as high as 85 cm s−1 at ...

Morphological variability of geographically distinct populations of the estuarine copepod Acartia tonsa

Variations in the number of spines on the left and right posterior dorsal and posterior margins of the prosome as well as the length of the prosome of Acartia tonsa from three estuaries, the upper western side of the Chesapeake Bay, Montauk Bay near the eastern end of Long Island Sound and the coast of Peru were determined. The length of the prosome and number of spines in each of the four locations were used as an indication of morphological similarity between the populations.

Copepod nauplii from the barrier reef of Belize

A study of areal distribution of the copepod nauplii near mangrove covered cays on the barrier reef of Belize was begun in the summer of 1989 and continued in the spring of 1990 with the collection of twenty samples from four locations. At distances in the order of 100 of meters to 1000 from the mangrove prop roots there were thousands of nauplii m−3. In the samples from Twin Cays where the plankton tows were made 15 m from the prop roots or less the average was 387 nauplii m−3. Copepod nauplii compose 60% of the metazoan plankton abundance in all of the samples. Harpacticoid nauplii were the largest single component of the plankton in every sample; they account for 42% to 76% of the copepod nauplii. Cyclopoid nauplii represent 13 to 40% and are second to the harpacticoid nauplii. Calanoid nauplii account for 2% to 23% of the copepod nauplii.

Diel distribution of copepods across a channel of an overwash mangrove island

The distribution of copepod species and their nauplii was studied in a narrow, blind channel on an overwash mangrove island offshore of Belize. Copepodids were sampled with a pump at five stations across the channel during a diel cycle. Diel changes of copepodid stages II – VI were marked by horizontal dispersal of Dioithona oculata, the dominant species, from swarms in the prop roots along the shore during the day to the edge of the prop root habitat at night. Migration of copepodids back to the prop roots appeared to be controlled endogenously because change from a night to a daytime age structure began before first light. Mean copepodid stage at subsurface depths in the channel and prop root edge decreased from 4.2 (with 6.0 = all adults) to 2.9 at predawn to 1.1 during day. The oceanic Oithona nana and O. simplex, and the coastal zone O. fonsecae were evenly distributed with depth and distance from shore during day and night, with avoidance of prop root shoreline during day. These species were much less abundant than Dioithona oculata in the prop roots, but of comparable or greater abundance in the channel. Coastal zone Acartia spinata exhibited evidence of swarming. Nauplii, sampled with a 25μm plankton net, were dominated by harpacticoid (50%) and cyclopoid (34%) nauplii, which generally were more abundant at 1m than at the surface and more abundant at night than the day. Lagrangian current measurements indicated velocities at ebb tide twice those of flood tide (1.9 vs. 0.8 cm s−1) and a minimal residence time of 5 days, which could result in advection of D. oculata nauplii out of the Lair Channel before their recruitment into swarms as copepodid stage II. Previously reported maximum swimming speeds of swarming D. oculata copepodid stages (2.0 cm s−1) and greater densities in prop roots and near the benthos may help copepodids avoid advection. The swarming behavior and diel horizontal migration (or dispersal) reported for D.oculata appears analogous to that of limnetic zooplankton, which may swarm among macrophytes along shorelines during the day to avoid visual predators and disperse or migrate away from the shoreline at night.

Internal wave observations off Punta Tuna, Puerto Rico

Internal waves in the northeastern Caribbean Sea off the south coast of Puerto Rico have been observed in a series of 381 vertical temperature profiles to a depth of 275 m. Internal waves with periods varying from one hour to the inertial period of the Caribbean Sea were observed. The surface tides in this region are of very small amplitude, less than 0.20 m. The observed internal tides in the upper 100 m are distinctly semi-diurnal in nature with a maximum amplitude of 30 m. At depths greater than 100 m the tides become more diurnal in nature with comparable amplitudes. These internal tides produce anomalies in the sea surface elevation comparable in magnitude to the dynamic height ranges reported for the region in atlases. The origin of the internal tides is somewhat problematical. These internal tides represent a significant sink for astronomical tidal energy.

Walking Behavior Observed in Phoxichilidium femoratum (Rathke, 1799) and Nymphon brevirostre Hodge 1863 Collected from Kandalaksha Bay of the White Sea, Russia

In this study, the walking behavior of Phoxichilidium femoratum and Nymphon brevirostre was investigated using video recordings. The walking behavior of P. femoratum while walking over the colonial hydroids that they normally feed on and on relatively smooth glass surfaces was observed. In the case of N. brevirostre, only walking on smooth glass was observed. The movement of the legs while waking does not display a metachronal pattern like that observed in the true spiders. As the animals move, the walking legs on the leading side of the animal are used to pull the animal forward while those on the trailing side make little or no contribution to the motion of the animal. The promoter/remoter motions of the coxa 1-coxa 2 joint of the walking legs are involved in azimuthal changes in the body’s orientation, but not in paraxial locomotion. The extension of the tarsus and propodus segments appears to occur as a result of hydrodynamic drag when the legs are being flexed and/or pressed against a solid substrate.

Variation of Von Vaupel Klein’s organ among genera of the Calanidae and Megacalanidae (Copepoda, Calanoida)

Von Vaupel Klein’s organ (VVKO), an association of the basal seta and proximal segment on the endopod of swimming leg 1 on many gymnoplean copepods, is surveyed on one species each of eight genera of calanids, viz., Calanoides acutus Giesbrecht, 1902, Calanus finmarchicus (Gunnerus, 1770), Canthocalanus pauper (Giesbrecht, 1888), Cosmocalanus caroli (Giesbrecht, 1888), Mesocalanus lighti (Bowman, 1955), Nannocalanus minor (Claus, 1863), Neocalanus robustior (Giesbrecht, 1888) and Undinula vulgaris (Dana, 1849), and three of megacalanids, viz., Bathycalanus richardi Sars, 1905, Bradycalanus typicus Sewell, 1947 and Megacalanus longicornis Sars, 1905. In this exploratory survey, VVKO shows significant variability among the eleven species in the shape of the distodorsal corner of the proximal endopodal segment, presence and location of denticles on the anterior face of the segment, presence and size of denticles along the distal margin of the segment, number of pores on the segment, shape of the seta that originates on the basis, and the nature of the basis at the origin of the seta.