Clifford A. Siegfried

Zebra Mussel (Dreissena polymorpha) Populations in the Seneca River, New York: Impact on Oxygen Resources.

The character and cause of a major depletion in dissolved oxygen (DO) observed in a 16-km reach of the Seneca River, New York, in the summer of 1993 was evaluated. The decline in oxygen concentrations was attributed to a recent severe infestation by the invading zebra mussel. Zebra mussel densities of 33 000-61 000 individuals m-2 were found in a 1.4-krn section, across which an average (n = 3) depletion in DO concentration of about 1.7 mg L-1 was observed. The estimated areal respiration rate for the zebra mussel population in this section (34 g m-2 d-1) nearly matched the areal sink calculated independently from DO budget calculations (44 g m-2 d-l). The zebra mussels also caused substantial decreases in phytoplankton biomass and increases in water clarity over the study reach. Loss in waste assimilative capacity is expected to occur in other alkaline hardwater rivers and streams with rock substrate in North America as the zebra mussel invasion spreads.

Planktonic rotifer community structure in Adirondack, New York, U.S.A. lakes in relation to acidity, trophic status and related water quality characteristics

AbstractThe structure of the mid-summer planktonic rotifer communities of 101 Adirondack lakes ranging in pH from 4.0 to 7.3 were characterized in relation to acidity and selected water quality parameters. More than 70 rotifer species were identified from collections in 1982 and 1984. None of the species collected could be considered acidobiontic or alkalibiontic. Keratella taurocephala was the most commonly collected rotifer, occurring in 94 of the study lakes. It was abundant throughout the range of pH investigated but was particularly dominant in acidic waters, averaging > 85 % of the rotifers collected from waters of pH < 5.0.Rotifer community structure can be related to three groups of water quality parameters. Community parameters (richness and diversity) are most highly correlated with parameters indicative of acidity status. Rotifer abundance correlates with trophic state indicators, i.e. chlorophyll a and total phosphorus, over the full range of pH investigated. However, in acidic lakes, rotifer abundance is related to true color and DOC, indicators of humic influences.The rotifer communities of the Adirondacks can be classified into four broad types: 1) A diverse, productive community of the more alkaline lakes, generally with ∼ 13 species, and dominated by Conochilus unicornis, Kellicottia bostoniensis, Kellicottia longispina, and Polyarthra major; 2) Relatively diverse communities of productive, highly colored acid lakes, with ∼ 8 species, and often with very large populations (> 200 · 1−1) dominated by K. bostoniensis and K. taurocephala; 3) Depauperate (< 4 species) communities of clear water acid lakes with generally low density populations dominated by K. taurocephala (> 90 % of rotifers in each sample); and 4) Extremely depauperate (2–3 species) acid lake communities associated with small lakes with high flushing rates dominated by C. unicornis.

Tributary Water Quality Feedback from the Spread of Zebra Mussels: Oswego River, New York

Dramatic changes in the water quality of the Oswego River system, including Oswego Harbor, since the early 1990s brought about by zebra mussel (Dreissena polymorpha) infestation are documented. The analysis is based on summertime (June to September) water quality monitoring of the Oswego Harbor (1981 and 1993), the mouth of the Oswego River (1983 to 1993), and three upstream sites in the Oswego River system (1990, 1991, and 1994), and two benthic surveys conducted along a 70 km reach of the system to the mouth of the Oswego River in 1994. It is estimated that water in the Oswego River was filtered more than twice over this length by the mussels in 1994 (at median flow) before it reached Oswego Harbor. The zebra mussel infestation converted the Oswego River and the harbor from a turbid (low clarity), phytoplankton-rich, nutrient-depleted system, to a system with distinctly greater clarity, reduced phytoplankton concentrations, enriched in soluble reactive phosphorus. Most of this impact was attributable to dense zebra mussel populations (e.g., ∼ 30,000 indiv/m2) in a 5 km river section, located > 60 km upstream of Oswego Harbor. These changes in tributary water quality represent a form of feedback associated with the spread of the zebra mussel from the Laurentain Great Lakes. Increased attached algae growth in the Great Lakes proximate to the inflow of infested tributaries is a reasonable expectation in response to the more available form of the phosphorous load.

Life history, population dynamics and production of Pontoporeia hoyi (Crustacea, Amphipoda) in relation to the trophic gradient of Lake George, New York

The life history characteristics, population dynamics and production of Pontoporeia hoyi in Lake George, New York, were studied from May 1981 through October 1982. P. hoyi, in terms of both density and standing crop, is the most prevalent member of the deep water macrobenthos of Lake George. It reproduces in the winter, with young being released in the late winter-early spring. At the southernmost study site, young released in the spring grew to 6–7 mm in length and bred during their first winter. At the remaining sites, P. hoyi required two years to complete its life cycle. This difference in life history characteristics can be related to food availability and temperature differences. The open waters of the south end of Lake George are not only more productive but are also more closely associated with the littoral zone, providing a wealth of bacteria-rich detritus for benthic deposit feeders. The greater food availability in the south basin of Lake George is reflected in significantly larger brood sizes and smaller size at maturity for P. hoyi populations from the south end of the lake.The southernmost study site has significantly greater P. hoyi density and standing crop than all other sites. The cohort of the year dominated density and standing crop at the southern site while the cohort of the previous year dominated standing crop at the other sites. Peak abundance ranged from 600 · m−2 at the north site to 2 900 · m−2 at the south site. Cohort production ranged from ∼2g · m–2 at the north site to ∼15g · m−2 at the south site.

Trophic relations of Crangon franciscorum Stimpson and Palaemon macrodactylus Rathbum: predation on the opossum shrimp, Neomysis mercedis Holmes

Crangon franciscorum and Palaemon macrodactylus are carnivorous shrimp in the Sacromento-San Joaquin River Delta. These shrimp prey primarily on the opossum shrimp, Neomysis mercedis. Behavioral and morphological differences result in P. macrodactylus stomachs containing a greater number of prey, on the average, than C. franciscorum. Dietary overlap and similarity were high (>80%) throughout the study. C. franciscorum is generally larger than P. macrodactylus and is able to ingest larger prey. This results in some size-related resource partitioning.

Changes in the Zooplankton of Onondaga Lake: Causes and Implications

ABSTRACT The zooplankton assemblage of ionically polluted, culturally eutrophic Onondaga Lake was monitored over the 1979–1989 interval, and compared to surveys conducted in 1968 and 1978. A major shift in the assemblage was apparent by 1987, soon after the closure (1986) of an industrial discharger of ionic (Cl; Na+ and Ca2+) waste. Species richness increased from 8 to 18 common species, and more efficient grazers, large-bodied cladocera and the calanoid copepod Diaptomus sitihides, became dominants. Until 1987, a single cyclopoid copepod, Cyclops vernalis, was the dominant component of zooplankton biomass. The most likely cause for the shift in the zooplankton assemblage of the lake is the reduction in salinity, and attendant precipitation of calcium carbonate, associated with the closure of the industry. Improved clarity in the lake, manifested largely as intervals of dramatic increases described as ‘clearing events’, observed annually since 1987, has been attributed to die shift to more efficient graz...

Acidity status and phytoplankton species richness, standing crop, and community composition in Adirondack, New York, U.S.A. lakes

The mid-summer phytoplankton communities of more than 100 Adirondack lakes ranging in pH from 4.0 to 7.2 were characterized in relation to 25 physical-chemical parameters. Phytoplankton species richness declined significantly with increasing acidity. Acidic lakes (pH < 5.0) averaged fewer than 20 species while more circumneutral waters (pH > 6.5) averaged more than 33 species. Phytoplankton abundance was not significantly correlated with any of the measured physical-chemical parameters, but standing crop parameters, i.e., chlorophyll a and phytoplankton biovolume, did correlate significantly with several parameters. Midsummer standing crop correlated best with total phosphorus concentration but acidity status affected the standing crop-phosphorus relationship. Circumneutral waters of low phosphorus content, i.e. < 10 µg·1−1 TP, averaged 3.62 µg·1−1 chlorophyll a whereas acidic lakes of the same phosphorus content averaged only 1.96 µg·1−1 chlorophyll a. The midsummer chlorophyll content of lakes of high phosphorus content, i.e. > 10 µg·1−1 TP, was not significantly affected by acidity status.Adirondack phytoplankton community composition changes with increasing acidity. The numbers of species in midsummer collections within all major taxonomic groups of algae are reduced with increasing acidity. The midsummer phytoplankton communities of acidic Adirondack lakes can generally be characterized into four broad types; 1) the depauperate clear water acid lake assemblage dominated by dinoflagellates, 2) the more diverse oligotrophic acid lake community dominated by cryptomonads, green algae, and chrysophytes, 3) the productive acid lake assemblage dominated by green algae, and 4) the chrysophyte dominated community. The major phytoplankton community types of acid lakes are associated with different levels of nutrients, aluminum concentrations, and humic influences.

Zooplankton Communities of Adirondack Lakes: Changes in Community Structure Associated with Acidification

ABSTRACT The structure of the zooplankton (rotifers + crustaceans) community of Adirondack lakes was evaluated relative to generalizations derived from the literature on the impacts of acidification. The generalization that the number of zooplankton species is reduced in acid lakes was strongly supported by the results of Adirondack studies. Acidity status appeared to be the most important factor determining zooplankton species richness in Adirondack lakes. Generalizations regarding community composition were not strongly supported. Although the relative biomass of daphnids and cyclopoid copepods tended to be reduced in acidic lakes they were also frequent dominants of the communities of acidic lakes. Only two of the “generalist” species of the Adirondack region, Diaptomus minutus and Keratella taurocephala, increased in relative importance in acidic lakes. Acidification had a significant effect on zooplankton biomass.

Brooktrout Lake case study: biotic recovery from acid deposition 20 years after the 1990 Clean Air Act Amendments.

The Adirondack Mountain region is an extensive geographic area (26,305 km(2)) in upstate New York where acid deposition has negatively affected water resources for decades and caused the extirpation of local fish populations. The water quality decline and loss of an established brook trout (Salvelinus fontinalis [Mitchill]) population in Brooktrout Lake were reconstructed from historical information dating back to the late 1880s. Water quality and biotic recovery were documented in Brooktrout Lake in response to reductions of S deposition during the 1980s, 1990s, and 2000s and provided a unique scientific opportunity to re-introduce fish in 2005 and examine their critical role in the recovery of food webs affected by acid deposition. Using C and N isotope analysis of fish collagen and state hatchery feed as well as Bayesian assignment tests of microsatellite genotypes, we document in situ brook trout reproduction, which is the initial phase in the restoration of a preacidification food web structure in Brooktrout Lake. Combined with sulfur dioxide emissions reductions promulgated by the 1990 Clean Air Act Amendments, our results suggest that other acid-affected Adirondack waters could benefit from careful fish re-introduction protocols to initiate the ecosystem reconstruction of important components of food web dimensionality and functionality.

ACIDIFICATION, VERTEBRATE AND INVERTEBRATE PREDATORS, AND THE STRUCTURE OF ZOOPLANKTON COMMUNITIES IN ADIRONDACK LAKES

ABSTRACT Midsummer zooplankton community structures of 50 Adirondack lakes were evaluated in relation to dominant vertebrate and invertebrate predators and selected limnological parameters. The most important factors structuring zooplankton grazer communities were extracted in a principal components analysis. The interaction of acidity status and vertebrate planktivore abundance explains the variation in lake scores for the first principal component. The second principal component was related to predation, while the third was related to lake trophic status and humic influence. The interaction of water quality and predator abundance structures grazer communities of Adirondack lakes.