The maximum size of plastic bead ingested by Bosmina Zongirustris and six species of Daphnia increased with increasing body size of the animals. The relationship between the diameter (,u) of the largest bead ingested ( y ) and carapace length (x, in mm) is given by an expression, y = 22x + 4.87. This relationship could be used to predict which members of a phytoplankton community would be available as food for different-sized --

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ABSTBACTFiltering rates of four species of Daphnia were measured at 15, 20, and 2%. Maximum filtering rattc increased with increasing temperature and increasing body size of the animal in all species, but a general equation relating filtering rate to body length could not bc derived.When filtering rates were expressed on a unit body weight basis, the species differed.Filtering rates of adult D. sch@dZeri and D. pulex were similar and at 20C were slightly higher than their rates at 15 and 25C. In contrast, filtering rates of D. magna and D. galeata mendotas increased with increasing temperature and at 20 ancl 25C were more than twice their rates at 15C.

Intermittent saline intrusions are a common feature of many coastal lakes and wetlands. These ecosystems are often important sites of biodiversity, biological productivity, and ecosystem services such as the removal of sediment, nutrients, and contaminants from inflowing rivers. Predicted effects of global climate change, including sea level rise, are likely to intensify saline intrusions into such ecosystems. Analyses of taxonomic diversity and abundance of zooplankton at different salinities in Lake Waihola, South Island, New Zealand, are supported by results of laboratory studies of salinity tolerances of 3 crustacean taxa Gladioferens pectinatus, Boeckella hamata and Daphnia carinata obtained from the lake. The field and laboratory analyses show that severe perturbations of zooplankton community structure and abundance are caused by even minor saline intrusions into Lake Waihola that raise the salinity to >1.2 psu. Our analyses of Lake Waihola, and data from brackish ecosystems around the world, show that even relatively small increases in salinity levels can drive such systems to a state of depleted biodiversity and abundance, altering ecosystem functioning.KEY WORDS: Zooplankton diversity · Zooplankton abundance · Climate change · Community structure · Shallow lake · Salinity · Lake Waihola · Saline intrusion Resale or republication not permitted without written consent of the publisherMar Ecol Prog Ser 251: [181][182][183][184][185][186][187][188][189] 2003 a medium sized (surface area = 5.4 km 2 ), shallow (mean depth = 1.15 m), tidal (mean tidal range ca. 0.40 m) lake, connected to the sea via a 10 km reach of the Taieri River, ca. 30 km southwest of the city of Dunedin. The lake has a diverse fish community and a high catch per unit effort (CPUE) relative to other New Zealand lakes, though not relative to shallow Danish lakes (Jeppesen et al. 2000). Lake Waihola has a hydraulic residence time of 153 d, based on non-tidal, freshwater inflows (Schallenberg & Burns 2003). During drought conditions, when water levels in the Taieri River are low and when other freshwater inputs are small, intrusions of saline water enter the lake, as occurred in the austral summers 1997/98 and 1998/99. Global climate change is expected to affect New Zealand in ways similar to the El Niño climatic pattern, in which westerly and southerly airflows dominate and the east coast of New Zealand experiences dry (drought) conditions more frequently (Mullan 1996, NZMfE 2001. During dry summers, Lake Waihola often experiences saline intrusions which create strong temporal and spatial salinity gradients within the lake. Results of a calibrated hydrological model of the Taieri catchment, which was run using meteorological inputs based on downscaled global circulation models and 2 global climate change scenarios (NZMfE 2001), indicated that runoff in the Taieri catchment will decrease during summer months under both scenarios (B. Fitzharris unpubl. data). In addition to decreased summer freshwater inputs, Lake Waihola will ...