Effects of river regulation and diversion on marine fish and invertebrates

Abstract

ABSTRACT1. The effects of freshwater regulation and diversion on the adult and larval stages of fish and invertebrates in coastal marine waters are reviewed.2. Potential impacts of river modification are highlighted based on our present understanding of the role of fresh water on the physical, chemical and biological processes on the marine environment. These include effects on migration patterns, spawning habitat, species diversity, water quality and distribution and production of lower trophic levels. The effect of dams on anadromous and catadromous fish are also presented.3. We discuss in detail the marine response to specific river regulation projects on the Nile, Indus and rivers flowing into the Black Sea, San Francisco Bay and James Bay in Canada. A decline in some coastal fisheries with an overall negative impact on the biota is generally associated with reductions in freshwater flow.4. Extensive ecological considerations are needed during the planning stage of large-scale freshwater modification projects to minimize potential impacts.

Effects of freshwater flow and phytoplankton biomass on growth, reproduction, and spatial subsidies of the estuarine copepod Pseudodiaptomus forbesi

“…Numerous mechanisms potentially contribute to these responses, such as variation in nutrient loading, stratification, and predator-prey interactions (Drinkwater & Frank, 1994;Alber, 2002;Kimmerer, 2002), and these may operate at different seasons and locations. At the landscape scale, the geomorphic, hydrologic, and biological complexity of most estuaries adds variability that may interfere with detection of mechanisms of change that are related to flow.…”

“…This variation appears to be a result of direct mechanisms rather than trophic effects because abundance of their zooplankton prey does not appear to vary with freshwater flow (Kimmerer, 2002;Kimmerer et al, 2013). However, abundance alone is an incomplete measure of productivity, and little is known about how population dynamics of estuarine zooplankton responds to flow or to phytoplankton biomass, which may itself respond to flow (Drinkwater & Frank, 1994). This paper examines the abundance, egg production rate, development, and growth of the introduced calanoid copepod Pseudodiaptomus forbesi to variation in freshwater flow and phytoplankton biomass in the brackish to freshwater region of the San Francisco Estuary.…”

The potential impact of an inter-basin water transfer project on nutrients (nitrogen and phosphorous) and chlorophyll a of the receiving water system

“…The Lesotho Highland Water Project improves the water quality of the Vaal River although it may increase algal growth (Davies et al, 1992). Most of the research focused on the potential threat to biodiversity conservation (Drinkwater and Frank, 1994;Gibbins et al, 2001;Snaddon and Davies, 1998). Only a few studies have concentrated on the effects of water transfers on the physical and chemical changes to water quality.…”

Australia's tropical river systems: current scientific understanding and critical knowledge gaps for sustainable management

“…barramundi: Lates calcarifer) fisheries. In addition to nutrient and organic matter inputs to support aquatic food webs, other linkages between catchment condition, freshwater inflows and marine life include habitat availability and accessibility, and the influence of flow on migratory and reproductive behaviour of aquatic organisms (Drinkwater and Frank 1994;Alber 2002;Gillanders and Kingsford 2002;Robins et al 2005). There clearly is a strong need for better understanding of the influence of catchment condition and catchment-scale processes on the ecological factors that support marine biodiversity as well as fisheries production and conservation in tropical estuaries (see also Blaber 2002).…”