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Society for Conservation Biology: 2002 Annual Meeting

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Society for Conservation Biology: 2002 Annual Meeting


Society for Conservation Biology 16th Annual Meeting July 14-July 19 2002
co-hosted by DICE and the British Ecological Society


Abstracts for Aquatic Ecology

Thursday 18th July, 13.30 - 15.00, Eliot Lecture Theatre 2

Chair: Jan Wanink




(BLOCK CAPITALS indicate the presenting author)


13.30 - 13.45
OGBOGU, SYLVESTER SUNDAY. Department of Zoology, Obafemi Awolowo
University, Ile-Ife 220005, Osun State, Nigeria, <sogbogu@oauife.edu.ng>.

CADDISFLIES OF OBAFEMI AWOLOWO UNIVERSITY, NIGERIA: IMPLICATIONS FOR FRESHWATER CONSERVATION

There are various forms of freshwater ecosystems in Obafemi Awolowo University campus in Ile-Ife, southwestern Nigeria. They include streams, rivers, ponds and reservoirs, utilised by the University community for various purposes. Therefore, they are subject to the impact of all forms of human activities on the campus. As such, it is necessary to investigate the diversity and distribution of aquatic invertebrates that are capable of responding to impairment of the ecosystems. The Order, Trichoptera
(Caddisflies) was chosen because apart from being used for biomonitoring,
it is highly diverse and yet a poorly-known group of aquatic invertebrates in Nigeria. The caddisfly fauna of the ecosystems was sampled between November 2000 and June 2001. It was observed that certain families were restricted to particular ecosystems due to the peculiarity of their in-stream microhabitat features. This suggests that caddisfly diversity can best be maintained by preserving the ecosystems with their respective microhabitats. Adequate protective measures and sustainable
utilisation of the ecosystems were recommended within the context of conservation strategy to reduce the impact of human activities on the caddisfly fauna.

13.45 - 14.00
KASANGAKI, AVENTINO, Jackson Efitre, Dennis Babaasa, Alastair McNeilage and Robert Bitariho. Institute of Tropical Forest Conservation, P.O. Box 44, Kabale, Uganda, <itfc@infocom.co.ug>.

AQUATIC MACROINVERTEBRATES IN BIOMONITORING IN BWINDI IMPENETRABLE NATIONAL PARK, UGANDA

Water quality can be an important indicator of change in a catchment area. Long-term monitoring of water quality can help in understanding changes in an ecosystem, as well as providing an important tool in assessing the effectiveness of management interventions. In Bwindi Impenetrable National Park, various interventions in the past may have affected the psycho-chemical characteristics and aquatic invertebrate communities of the rivers, including logging, mining and agricultural encroachment. In order to establish a baseline for long term monitoring, and to investigate seasonal variation in physicochemical parameters and macroinvertebrate diversity in Bwindi, we monitored pH, conductivity, dissolved oxygen, water discharge, water levels and river width over one year. We also sampled the macroinvertebrates using a Surber sampler and identified them to the family level. Twelve sites were sampled in total, with three sites on each of four rivers. Some taxa were widely distributed, while others were more restricted in distribution. A relationship between invertebrate richness and the level of catchment quality was found at some study sites. Using ordination and other classification techniques, we anticipate identifying indicator taxa for monitoring changes within the catchment.



14.00 - 14.15
WANINK, JAN H., Egid F.B. Katunzi, Martien J.P. van Oijen and Frans Witte. Institute of Evolutionary and Ecological Sciences, University of Leiden, P.O. Box 9516, 2300 RA Leiden, The Netherlands, <wanink@rulsfb.leidenuniv.nl> (JHW, FW), Haplochromis Ecology Survey Team (HEST), P.O. Box 1866, Mwanza, Tanzania (JHW), Tanzania Fisheries Research Institute (TAFIRI), P.O. Box 475, Mwanza, Tanzania (EFBK), Naturalis, National Museum of Natural History, P.O. Box 9517, 2300 RA Leiden, The Netherlands (MJPvO).

ADAPTIVE RESPONSES OF FISH SPECIES SURVIVING ANTHROPOGENIC PERTURBATION IN LAKE VICTORIA

Eutrophication, overfishing and introducing aliens caused a dramatic decline in Lake Victoria’s fish diversity during the 1980s. To survive, species had to cope with increased hypoxia, decreased transparency and increased predation pressure. We investigated adaptive responses in four surviving zooplanktivores, three cichlids and a cyprinid, in the Mwanza Gulf (Tanzania). Distribution patterns before and after the species reduction were compared using daytime and nighttime bottom and surface trawls, and whole-column gill nets over the 24-h cycle. Fish size, stomach contents, maturity, fecundity and gill morphology were checked. Habitat shift and diet expansion, particularly to macrobenthos, was found in all species, probably enhancing scope for growth. The cyprinid increased its growth rate and reproduced earlier, while the cichlids increased their fecundity. Preliminary morphological work on the cyprinid and one of the cichlids revealed an increase in gill surface, an assumed response to increased hypoxia. Gill rakers decreased in numbers or changed in form, in accordance with the shift to benthic feeding. Retina morphology may have formed an important pre-adaptation in the surviving species, allowing for spawning in turbid water. However, we conclude that the observed behavioural, physiological and morphological responses of the ‘former’ zooplanktivores must have contributed considerably to their survival.



14.15 - 14.30
WHITE, SETH M. and Frank J. Rahel, PO Box 3166, Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming 82071, USA <oclarki@uwyo.edu>

TRENDS IN BONNEVILLE CUTTHROAT TROUT PRODUCTION AND SURVIVAL: IMPLICATIONS FOR CONSERVATION IN A LANDSCAPE IMPACTED BY CATTLE

We examined the effects of geomorphology, riparian vegetation, and winter ice on the spatial distribution of age-0 Bonneville cutthroat trout (Oncorhyncus clarki utah) in Thomas Fork headwater streams, western Wyoming, USA. Reach-scale distribution patterns of young fish were analyzed in two drainages: Huff Creek, a stream heavily impacted by cattle grazing, and Water Canyon, a reference system with abundant riparian vegetation and beaver activity. Geomorphic and riparian conditions were measured in areas of high, medium, and low fish density. Fish density estimates in both streams decreased from Fall 2000 to Fall 2001, but areas of high and low relative abundance remained consistent between years. The strongest models predicting fish densities were different for each stream. For example, upwelling of hyporheic water and winter stream ice openings were positively correlated with fish densities in Huff Creek, but not in Water Canyon. Although age-0 fish abundance estimates were greatest in Huff Creek, we have preliminary data showing that in Water Canyon, survival of age-0 fish into the next age class was much greater. These results suggest that Huff Creek may be an ecological trap where high densities of age-0 fish are produced but not recruited into the next age class.



14.30 - 14.45
Räsänen, Katja, ANSSI LAURILA and Juha Merilä. Department of Population Biology, Evolutionary Biology Center, Uppsala University, Norbyvägen 18D, SE-75236 Uppsala, Sweden, <anssi.laurila@ebc.uu.se> (KR, AL), Division of Population Biology, Department of Ecology and Systematics, P.O. Box 17, FIN-00014 University of Helsinki, Finland (JM)

LOCAL ADAPTATION TO ACIDIFICATION IN THE MOOR FROG RANA ARVALIS

Anthropogenic acidification has resulted in severe environmental problems and loss of biodiversity since the onset of industrialisation. However, long-term acidification is also likely to cause directional selection and organisms may evolve adaptations to locally varying acidity. In a series of laboratory experiments, we investigated whether moor frog Rana arvalis populations from southern Sweden, where acidification has been a severe problem since 1960’s, are adapted to local acidity, and what is the relative importance of additive genetic versus maternal effects in acid stress tolerance. We found evidence for local adaptation as indicated by population differences in embryonic survival and larval developmental rate. Quantitative genetic studies revealed that embryonic survival under acid conditions is maternally determined and that the adaptation is related to the jelly membranes surrounding the eggs. Maternal effects also largely determine adaptation in larval development rate, larvae from large eggs developing faster under acid conditions in the acid origin population. The results indicate that moor frog populations can, within certain limits, adapt to acidification, and that maternal effects may provide a fast way for local adaptation to acidity in amphibians.



14.45 - 15.00
TRIGWELL, JACQUELINE A., Phil Buckley, and Georges B. J. Dussart. Ecology Research Group, Canterbury Christ Church University College, North Holmes Road, Canterbury, Kent CT1 1QU, UK, <jat1@canterbury.ac.uk>.

THE EFFECTS OF CHANGES IN SEWAGE TREATMENT IMPACTS ON AN ESTUARY

The Ecology Research Group has carried out quarterly monitoring of biological, physical and chemical parameters of the River Stour and Pegwell Bay since 1993. During this time, two effluent treatment works have been built on the river and Richborough Power Station decommissioned. There have also been climatic changes over the last nine years, which has resulted in significant periods of flooding during the autumn, winter and spring months of recent years. Since surveys began, the River Stour has witnessed movement in the distribution of invertebrates and an overall increase in the number of families recorded. Between 1993 and 1999, the abundance of annelids and molluscs increased but there appeared to be fewer crustacea. In addition, there seemed to have been a decline in the number of molluscs found in Pegwell Bay. Nitrate, orthophosphate and suspended solids are significantly lower than when monitoring began but the percentage of organic material in the water column has increased. There has also been an increase in the concentration of heavy metals bound in the sediments.