G. S. Kleppel

Environmental regulation of feeding and egg production by Acartia tonsa off southern California

The feeding, diet and egg production of the copepod Acartia tonsa were dermined during ten experiments in Los Angeles Harbor, California, between November 1986 and October 1987. Copepods were incubated in situ, in quasi-natural food environments. Water temperatures ranged from 14.6 to 21.5°C. Particulate organic carbon and nitrogen (POC and PON) were high (534 to 3710 μg Cl-1, 51 to 459 Nl-1) but dominated by small (<8 μm diam) particles. Plankton (phytoplankton and microzooplankton) C-biomass composed about 10% of the total POC and was usually dominated by particles >8 μm. Plankton biomass was always low. Daily ingestion rates ranged from 3 to 96% of body C; egg production ranged from 4 to 35% of body carbon. Mean ingestion and egg production rates during spring-summer were 1.9 and 1.5 times higher than average for the entire study, respectively. The average gross efficiency of egg production for the study was 80%; the spring-summer mean was 41%. Bivariate and multiple-regression analyses revealed that the ingestion rate was dependent upon both temperature and food availability, but that, below 21°C, egg production depended more upon temperature than upon food concentration. To detect dietary preferences, the composition of diet was compared with that of the food supply. Selective feeding was infrequent, but the diet was often dominated by dinoflagellates and ciliates. It would appear that within metabolic limits governed by temperature, the feeding response of A. tonsa is dependent upon food concentration, while egg production depends more on qualitative attributes of the food supply.

Diets of calanoid copepods on the West Florida continental shelf : Relationships between food concentration, food composition and feeding activity

Bottle incubations were conducted in March, July/August and October 1992. to measure the daily rations (R) and objectively characterize the diets of the calanoid copepodsEucalanus elongatus, Undinula vulgaris, Centropages velificatus andTemora stylifera from the west Florida continental shelf. Daily rations,R, were clustered around two, order-of-magnitude different means, 1.3 and 11.2% of body C d−1, representative of quiescent and active feeding modes, respectively. The food concentration at which the transition from quiescent to active mode occurred was influenced by food particle size. In the quiescent mode, diets were dominated by nanoplankton, whereas no food type dominated the diet in the active mode. Selective feeding, defined as a statistically significant difference between the frequency distributions of foods in the diet and environment, occurred in both quiescent and active copepods. However, what appeared to be selective feeding in quiescent copepods could be explained by processes that passively modified the distribution of the diet relative to that of the food supply. Conversely, selective feeding in active copepods apparently resulted from foraging for particles >5 μm in diameter in food environments dominated by nanoplankton (<5 μm).

Egg Production of the Copepod Acartia tonsa in Florida Bay During Summer. 1. The Roles of Food Environment and Diet

The diet and egg production rate ofAcartia tonsa were measured during the thermally stable period between June and October 1995 at four locations in inner and outer Florida Bay. We sought to characterize the role ofA. tonsa in the bay’s pelagic food web, which has been changing since 1987, when the dominant submerged vegetation began shifting from benthic seagrasses to planktonic algae. At Rankin Lake, a shallow basin on the north side of the inner bay, where extensive seagrass mortality and persistent cyanobacteria blooms have occurred, microplankton biomass was relatively high and dominated by heterotrophic protists and dinoflagellates. Nanoplankton at Rankin, Lake, while numerically abundant, usually contributed only a small portion of the biomass. The ingestion rate ofA. tonsa in Florida Bay varied independently of food concentration (i.e., total microplankton biomass), but rates were higher (mean±SD =3.88 ± 0.73 μg C copepod−1 d−1) on the north side of the bay than on the south side (0.78 ±0.11 μg C copepod−1 d−1). Microzooplankton and dinoflagellates were important dietary constituents, especially in the vicinity of Rankin Lake. Egg production in this region (mean ± SD = 14.2 ± 7.7 eggs female−1 d−1) was considerably high than the baywide mean (5.8±0.81 eggs female−1d−1), and principal components analysis revealed associations between egg production and both dietary microzooplankton and dinoflagellate biomass. However, although grazing rates were relatively high in the inner bay,A. tonsa removed only 1–6% of the primary production from the water column during the summer and its egg production rates were low relative to typical rates for the species.

Responses of Emergent Marsh Wetlands in Upstate New York to Variations in Urban Typology

Although it has been repeatedly demonstrated that urbanization has negative environmental consequences, the conversion of land to urban use is increasing worldwide and is not likely to abate. We tested the hypothesis that different urban typologies, i.e., distributions of human population and infrastructure, differentially influence the water quality and ecological functionality of emergent marsh wetlands in New York States Hudson River Valley. Wetlands were studied in two watersheds, defined as landscapes bounded by ridge lines, containing traditional small-town development and two watersheds containing suburban typologies. Land cover attributes were evaluated by analyzing ground-truthed, orthophotoquad data with a GIS. Water quality, the cover and biomass of emergent vascular plants, phytoplankton biomass, zooplankton biomass, and planktonic trophic transfer efficiency were measured in the wetlands during the fall of 2000, the summer and fall of 2001, and the summer and fall of 2002. Of the 13 variables measured, five exhibited typological differences according to the results of student t-tests. The interactions between these variables were quantified by least squares regression. Two key attributes of urban systems, i.e., the amount of vegetated buffer between the urban landscape and receiving waters and the amount of land in urban use, appeared to strongly influence water quality and ecosystem function in the wetlands studied. Nonpoint source loading and the success of exotic emergent macrophytic invasions varied directly with urban land use and inversely with buffer width. Trophic transfer efficiency declined with urban land use and increased with buffer width. The amounts of buffer and urban land use in a watershed appear to vary systematically with urban typology. Thus, watersheds that were developed in accordance with suburban design criteria exhibited more urban land use and less riparian buffering than did watersheds containing comparably scaled traditional small-town typologies.

Using Sheep to Control Purple Loosestrife (Lythrum salicaria)

Abstract We investigated the use of sheep for controlling the spread of purple loosestrife in a wet meadow in upstate New York from June to August 2008. Changes in the purple loosestrife population and vascular plant community structure were monitored as a function of the grazing of two ewes, “rotated” through four “experimental” paddocks at 2- to 3-d intervals. Comparative data were collected in “reference” paddocks from which sheep were excluded. Purple loosestrife was heavily grazed and most plants did not flower in experimental paddocks. Purple loosestrife cover declined by 40.7% in the experimental paddocks but did not change significantly in the reference paddocks. After grazing, species richness was 20% higher in experimental than reference paddocks. Nomenclature: Purple loosestrife, Lythrum salicaria L Interpretive Summary: Although livestock is widely used to manage nuisance plant species on rangelands, little is known about the effectiveness of this approach, called “targeted grazing,” in wetlands, and controlled, systematic studies on the effectiveness of targeted grazing are scarce. We investigated the efficacy of using Romney sheep to control the spread of purple loosestrife in a wet meadow in upstate New York. We were interested in the impacts of the sheep on both the invasive population and on the larger plant community. The sheep were rotated through a system of small (200-m2) paddocks using a protocol, intensive rotational grazing (IRG), that employs high stocking densities, i.e., two to four times more livestock biomass than conventional grazing, and high frequency rotations (2 to 3 d per paddock). As such, IRG mimics the distribution, in time and space, of large, wild, herbivorous herding mammals on a landscape. The sheep fed on purple loosestrife (and other invasives), preventing flowering and reducing purple loosestrife cover by about 40%, relative to reference paddocks from which sheep were excluded. After the grazing phase of the study, species richness was 20% higher in the grazed paddocks than in the reference paddocks. Although a great deal remains to be learned about the impacts of targeted grazing and its underlying mechanisms, it appears that the technique can be used to help manage purple loosestrife, and perhaps other invasive plant species, in emergent wetlands and wet meadows.

Invasive Plant Control by Livestock: From Targeted Eradication to Ecosystem Restoration

©2011 by the Board of Regents of the University of Wisconsin System. Figure 1. Multiflora rose vitality (percent of plant with foliated, pliable stems). Mean (± 1 standard error) of 20–25 randomly selected plants in grazed (Boer goats; dashed line) and ungrazed (solid line) portions of a pasture at Glynwood Center, Cold Spring, New York, May–October 2009 and April–October 2010. Invasive Plant Control by Livestock: From Targeted Eradication to Ecosystem Restoration g.s. Kleppel, caroline B. girard (Biodiversity conservation & Policy Program, University at albany, sUnY, albany, nY 12222, gkleppel@albany.edu, 518/442-4338), sophia caggiano, and Erin laBarge (Department of Biological sciences, University at albany)

Grazing and the Coupling of Biodiversity in Vascular Plant and Soil Microbial Communities

Abstract This study sought to ascertain how different grazing management protocols affect the coupling between soil microbial and vascular plant communities. Changes in microbial and plant communities were observed over a grazing season (Spring 2013–Spring 2014) at 2 previously ungrazed agricultural sites—a moist lowland (Longfield Farm) and a drier upland (Normanskill Farm)—near Albany, NY. Each landscape was divided into 6 fenced enclosures (paddocks). One paddock at each farm was managed by a managementintensive grazing (MIG) protocol, which employs high stock density and frequent rotations. A second paddock was managed by continuous grazing (CG) at lower (conventional) stock density. A third paddock at each site was left ungrazed (U). Three “simulation” paddocks were used to explore the underlying dynamics of grazer-microbe-plant interactions. By spring 2014, plant species richness (S) was significantly higher (t-tests: P < 0.05) in the MIG paddocks at both farms. At Normanskill Farm, S was correlated with both microbial diversity and biomass, while at Longfield Farm, S was independent of microbial diversity and biomass but varied directly with soil moisture. Our findings suggest that while MIG leads to increased S relative to CG, different forcing factors may be responsible for the enhancements in upland and lowland systems.

Introduction: The Natural History of Agricultural Landscapes

During the past 10 millennia, agriculture has evolved from a tentative “conversation with nature” to a series of exact sciences that have changed our species’ relationship with the natural world. The ability to produce food in large quantities at a single location has been transformative for our species and for the majority of ecosystems on Earth. It has provided an alternative to hunting and gathering, and permitted the emergence of settlements, cities, and civilizations. It has allowed for the division of labor and contributed to the exponential expansion of human population, both in terms of numbers of individuals and geographic range. Simultaneously, agriculture has had and continues to have devastating impacts on natural systems and processes. As a primary contributor to the massive elimination of species and the millennia-long trend toward global deforestation, the loss of tens of billions of tons of soil annually, the contamination of the atmosphere with climate-altering chemicals, and the pollution of lakes, rivers, and coastal marine waters, agriculture is as much a scourge to our life-support system as it is an essential element of that system (see for reviews, Shortley and Abler 2001). As we approach the Earth’s carrying capacity for our species, we will need to produce ever more food, until, potentially, the ability to meet global food demand collapses under the weight of 9–10 billion people in the middle of this century (FAO 2009, Tilman et al. 2011). The transformation of our food system to one that is more efficient and sustainable than it is currently requires input not only from the agricultural community but from a diversity of disciplines. Natural historians will contribute substantively to that conversation, and the Northeast may be a bellwether for the emergence of a regenerative agriculture that simultaneously nurtures us and the ecosystems to which we belong. The agricultural landscape matrix of the northeastern United States (here considered New York and New England) emerged from the practices of small-holder European farmers of the 17 century. It has adapted over 4 centuries to the region’s climate, topography, developing technologies, and cultures. While pre-Colombian natives cleared land for maize-based agriculture, and burned some of the region’s extensive forests to drive game, nearly 50% of the forests in the Northeast were cleared by European immigrants and their progeny between the 17 and 19 centuries (Thompson et al. 2013). Most of that land was repurposed for food and fiber production. As agriculture transitioned westward during the 19 and 20 centuries, much of the farmland in New York and New England that had not been merged into large parcels as dictated by the emerging industrial model of agriculture, was abandoned or sold for development. Between 1900 and 1997, the amount of farmland in the Northeast declined by more than 73% (Fig. 1). This trend appears to have

The Effect of Grazing Regime on Grassland Bird Abundance in New York State

Abstract Grassland breeding bird abundances in New York State mirror a national downward trajectory as land-use changes degrade, destroy, and fragment suitable habitat. We quantified and compared bird abundances on pastures that were subject to continuous grazing, minimal rotation, or holistic resource management. We hypothesized that grassland bird abundance varied systematically with pasture management approaches. We measured grassland bird abundances using 40-m radius point counts performed on 27 pastures. Further, we assessed vegetation and environmental parameters to characterize the available habitat on each pasture. Holistic resource managed pastures had 1.5 and 4.5 times higher average abundances of obligate grassland birds than minimally rotated or continuously grazed pastures, respectively. Overall, our results indicate that farms can employ strategies that promote grassland bird habitat and may therefore have a positive influence on grassland bird metapopulations in New York State.

Grazing as a Control for the Spread of Mile-a-Minute (Persicaria perfoliata) and the Restoration of Biodiversity in Plant Communities in a Lower New York State Parkland

The invasive annual vine, mile-a-minute (Persicaria perfoliata), has disrupted native plant communities throughout the mid-Atlantic United States and is rapidly spreading. This study investigated the efficacy of using sheep to control the spread of mile-a-minute at Ward Pound Ridge Reservation in Westchester County, NY. Animals were rotated, at a high stocking density (equivalent to ca. 9 tons of grazer biomass ha−1) through a system of 200 m2 enclosures at high frequency (2–3 day enclosure−1). An ungrazed reference area was delineated adjacent to each of the grazed enclosures. Cover class analysis was performed, species richness was determined and the inflorescence (presence of flower clusters) of individual mile-a-minute plants was monitored in all enclosures and corresponding reference areas prior to the commencement of grazing and following the final grazing rotation. Prior to sheep deployment, mile-a-minute cover was 3.8 times greater in grazed enclosures than in ungrazed areas. Following grazing, mile-a-minute cover in grazed enclosures (6.69% ± 5.9%) was 3.6 times lower in the ungrazed areas (20.6 ± 21.2%). Furthermore, mile-a-minute inflorescence was significantly lower (X2 = 98.019, n = 4; p < 0.001) in grazed enclosures than in ungrazed areas after completion of the grazing phase of the study. Following the final grazing rotation, an increase in vascular plant species richness (+ 23.08%), was observed in response to grazing whereas a decrease in species richness (−6.94%) was observed in ungrazed areas.