William H. Massmann

Bio: William H. Massmann is an academic researcher from Virginia Institute of Marine Science. The author has contributed to research in topics: Plankton & Continental shelf. The author has an hindex of 9, co-authored 16 publications receiving 198 citations.

Spawning of the cobia,Rachycentron canadum, in the Chesapeake Bay area, with observations of juvenile specimens

Abstract: Pelagic eggs collected in Atlantic coastal waters adjacent to Chesapeake Bay have been identified as those of the cobia,Rachycentron canadum (Linnaeus). The egg diameters ranged from 1.16 mm to 1.42 mm with a mean of 1.27 mm. The single large oil globule had a mean diameter of 0.38 mm.

The Pelagic Eggs and Early Larval Stages of the Black Drum from Chesapeake Bay

Abstract: FISH, MARIE P. 1954. The character and significance of sound production among fishes of the western North Atlantic. Bull. Bingham Oceanogr. Coll. 14:1-109. HERALD, E. S., AND R. P. DEMPSTER. 1957. Courting activity in the whitelined squirrelfish. Aquarium J. 28:43-44. JOHNSON, M. W. 1948. Sound as a tool in marine ecology, from data on biological noises and the deep scattering layer. J. Marine Res. 7:443-458.

Movements of striped bass tagged in Virginia waters of Chesapeake Bay

Abstract: In winter and spring of 1957 and 1958, 2429 striped bass ranging in length from 7 to 35 inches were tagged in the York, James, and Rappahannock Rivers of Virginia and 675 were recaptured. Fish were recaptured by stake, drift, and anchor gillnets, fyke nets, pound nets, hook and line and an oyster dredge. Ninety-four percent of the recaptured fish were taken in the same river system in which they were tagged. Striped bass from the York River moved more extensively than those from the Rappahannock; those from the James River moved least. Twelve fish moved outside of Chesapeake Bay and were recaptured in coastal waters between Maine and North Carolina. Most fish recaptured in fall and winter were taken in the same river system in which they were tagged, while some of those recaptured in spring and summer moved considerable distances. Almost all striped bass less than 12 inches in length remained in the river system in which they were tagged. The distribution of tag returns suggested that subpopulations of striped bass were present in the York and Rappahannock and James Rivers. The James River fish rarely mixed with those from other areas in Chesapeake Bay.

Investigations of inner continental shelf waters off lower Chesapeake Bay

Abstract: A series of monthly exploratory cruises into the neritic waters of the Atlantic Ocean adjacent to lower Chesapeake Bay were initiated late in1959 to: (a) locate the eggs and larvae of fishes spawning in the area; and (b) to trace the transport of these stages by surface and subsurface currents into the Chesapeake Bay system. This paper will serve as an introduction to a proposed series describing the results of the cruises. The survey area, which covers 50 nautical miles offshore and 60 miles in a north-south direction, is the neritic zone lying within the 20 fathom contour and extending from False Cape on the south to Wachapreague Inlet at the northern limit. Twenty-two offshore stations in addition to three stations in lower Chesapeake Bay were sampled monthly with surface and bottom plankton nets. Routine hydrographic data were taken at each station. Surface and bottom water samples from the cruises of December through May indicated these preliminary points: From December through March the water column was essentially homogeneous with respect to temperature. Vernal warming began in April and thermal stratification progressed through May. The distribution of salinities was generally coastal in character with isohalines parallel to the coastline. The discharge of effluent from Chesapeake Bay produces frequent deviations from the normal coastal pattern. In general, the major component of the discharge from Chesapeake Bay passes out around Cape Henry and proceeds southward. Drift bottle returns indicated that the survey area is crossed by a southerly drift having a velocity of 10 to 14 miles per day.

Distribution of larvae of the naked goby,Gobiosoma bosci, in the York River

Abstract: Larvae of the naked goby were collected in large numbers during a series of plankton surveys made in the York and Pamunkey Rivers in the spring and summer months of 1961 and 1962. The greatest numbers and the smallest larvae were taken upriver from the area where adult gobies are commonly found. The distribution of larvae indicate that they did not move upriver in the subsurface wedge of salty water, however their presence far upriver from the apparent spawning area cannot be explained. The larvae appeared in the same upstream areas in equal abundance during late May and early June in both 1961 and 1962.

Tangled webs: reciprocal flows of invertebrate prey link streams and riparian zones

Abstract: SUMMARY 1. Streams and their adjacent riparian zones are closely linked by reciprocal flows of invertebrate prey. We review characteristics of these prey subsidies and their strong direct and indirect effects on consumers and recipient food webs. 2. Fluxes of terrestrial invertebrates to streams can provide up to half the annual energy budget for drift-feeding fishes such as salmonids, despite the fact that input occurs principally in summer. Inputs appear highest from closed-canopy riparian zones with deciduous vegetation and vary markedly with invertebrate phenology and weather. Two field experiments that manipulated this prey subsidy showed that it affected both foraging and local abundance of stream fishes. 3. Emergence of adult insects from streams can constitute a substantial export of benthic production to riparian consumers such as birds, bats, lizards, and spiders, and contributes 25–100% of the energy or carbon to such species. Emergence typically peaks in early summer in the temperate zone, but also provides a low-level flux from autumn to spring in ice-free streams. This flux varies with in-stream productivity, and declines exponentially with distance from the stream edge. Some predators aggregate near streams and forage on these prey during periods of peak emergence, whereas others rely on the lower subsidy from autumn through spring when terrestrial prey are scarce. Several field experiments that manipulated this subsidy showed that it affected the short-term behaviour, growth, and abundance of terrestrial consumers. 4. Reciprocal prey subsidies also have important indirect effects on both stream and riparian food webs. Theory predicts that allochthonous prey should increase density of subsidised predators, thereby increasing predation on in situ prey and causing a negative indirect effect via apparent competition. However, short-term experiments have produced either positive or negative indirect effects. These contrasting results may be due to characteristics of the subsidies and individual consumers, but could also result from differences in experimental designs. 5. New study approaches are needed to better determine the direct and indirect effects of reciprocal prey subsidies. Experiments coupled with comparative research will be required to measure their effects on individual consumer fitness and population demographics. Future work should investigate whether reciprocal prey fluxes stabilise linked stream–riparian ecosystems, explore how landscape context affects the magnitude and importance of subsidies, and determine how impacts of human disturbance can propagate between streams and riparian zones via these trophic linkages. Study of these

Dramatic Declines in North Atlantic Diadromous Fishes

Abstract: We examined the status of diadromous (migratory between saltwater and freshwater) fishes within the North Atlantic basin, a region of pronounced declines in fisheries for many obligate marine species. Data on these 24 diadromous (22 anadromous, 2 catadromous) species are sparse, except for a few high-value forms. For 35 time series, relative abundances had dropped to less than 98% of historic levels in 13, and to less than 90% in an additional 11. Most reached their lowest levels near the end of the observation period. Many populations persist at sharply reduced levels, but all species had suffered population extirpations, and many species are now classified as threatened or endangered. Habitat loss (especially damming), overfishing, pollution, and, increasingly, climate change, nonnative species, and aquaculture contributed to declines in this group. For those diadromous fishes for which data exist, we show that populations have declined dramatically from original baselines. We also discuss the consequen...

Early life history and recruitment in fish populations

Abstract: The early life history of fishes and its role in recruitment processes. Recruitment in fish populations: the paradigm shift generated by ICES committee A. Parent-progeny relationships. Selective processes in the early life history. The contribution of early life history studies to our understanding of recruitment. Conclusions.

Episodic hypoxia in Chesapeake Bay : interacting effects of recruitment, behavior, and physical disturbance

Abstract: Physical disturbance can be an important force at the individual, population, and community levels of organization. The effects of disturbance may differ for mobile and sessile organisms, however, because of differences in the potential for escape and postdisturbance recolonization by survivors. I used field sampling and laboratory experiments to examine how episodic movement of severely oxygen—depleted (hypoxic) bottom water into nearshore habitat in the Chesapeake Bay affects population density, recruitment, and reproduction of a mobile species–the naked goby (Gobiosoma bosc), a benthic oyster bed fish. Oxygen depletion is a common physical disturbance in freshwater, estuarine, and coastal aquatic systems. In this study, episodic hypoxia influenced mortality, size structure of the population, reproductive behavior, and spatial distribution. Intrusion of severely hypoxic water occurred in late July and early August during the 2—yr study. These intrusions coincided temporally with peak periods of recruitment, and caused the most severe drops in dissolved oxygen concentrations in deep and mid—depth areas of the oyster reef, where recruitment was highest. Laboratory experiments suggested that newly settled recruits require higher oxygen concentrations for survival than do older individuals. Field samples also indicated that these new recruits are less able to escape to more highly oxygenated shallow water refuges when an intrusion occurs. Thus, the spatial and temporal patterns of recruitment and disturbance, and physiological requirements, combine to result in extremely high mortality of new recruits during severe intrusions. In contrast to effects on new recruits, some large juveniles and adults successfully migrate inshore when oxygen levels decline. In both field samples and laboratory experiments, adult males continued to guard eggs and shelters until dissolved oxygen closely approached lethal levels. Calculations based on size—specific physiological tolerances and swimming speeds suggest that the occurrence of lethal conditions in the fluctuating environment may be more predictable to larger individuals than to new recruits. This predictability may increase the possibility of an appropriate response to low oxygen disturbances by large juveniles and adults. After the disturbance abates, surviving individuals recolonize abandoned areas. This ability of mobile animals to recolonize a disturbed area as adults or juveniles, rather than solely through reproduction, may lead to differences in postdisturbance ecological interactions and differences in selection for colonizing ability between mobile and sessile species.

Life history, feeding habits, and functional morphology of juvenile sciaenid fishes in the york river estuary, virginia1,2

Abstract: Four abundant sciaenid fishes, Cynoscionregalis, Bairdiellachrysoura, Micropogoniasundulatus, and Leiostomusxanthurus, use the York River, Va., as a nursery ground and as an adult seasonal feeding ground. In addition, six species ofsciaenids, Menticirrhussuxatilis, M. americanus,Sciaenops ocellata, Cynoscion nebulosus, Pogoniascromis, and Larimusfasciatus, are present in the estuary occasionally. Yearling C. regalis were first caught in April and young-of-the-year in July or August. Yearling B. chrysoura were first caught in March or April and young-of-the-year in July or August. Juvenile Micropogoniasundulatus and Leiostomusxanthurus may be present in the York River all year-round. Young-of-the-year L. xanthurus were first caught in April and M. undulatus were first caught in August. Small M. undulatus «20 mm TL) were caught from August to June, which may indicate a prolonged spawningseason (or a late spawningstock). Emigration to the ocean was found in all the four species during late fall or early winter. Water temperature and dissolved oxygen seemedto be the most important factors in the spatial and temporal distributions of these four species in the York River. Mouth position, dentition, gill rakers, digestive tract, pores and barbels, nares, and body shape ofsix sciaenid species, Larimusfasciatus, C. regalis, B. chrysoura, M. undulatus, Menticirrhus suxatilis, and Leiostomusxanthurus, were found to be important in locating and ingesting prey in the water column. Stomach contents indicated that the food partitioning of these six species was closely correlated with the species and their prey habitat. Larimusfasciatus, C. regalis, andB.chrysoura fed mainly above the bottom, whereas Micropogonias undulatus, Menticirrhus suxatilis, and L. xanthurus fed on epifauna, infauna, or both. Juvenile sciaenids are able to coexist in the same area because ofdifferences in spatial and temporal distribution, relative abundance, and food habits.