Effects of Harmful Algal Blooms on Fish and Shellfish Species: A Case Study of New Zealand in a Changing Environment

Abstract

Harmful algal blooms (HABs) have wide-ranging environmental impacts, including on aquatic species of social and commercial importance. In New Zealand (NZ), strategic growth of the aquaculture industry could be adversely affected by the occurrence of HABs. This review examines HAB species which are known to bloom both globally and in NZ and their effects on commercially important shellfish and fish species. Blooms of Karenia spp. have frequently been associated with mortalities of both fish and shellfish in NZ and the sub-lethal effects of other genera, notably Alexandrium spp., on shellfish (which includes paralysis, a lack of byssus production, and reduced growth) are also of concern. Climate change and anthropogenic impacts may alter HAB population structure and dynamics, as well as the physiological responses of fish and shellfish, potentially further compromising aquatic species. Those HAB species which have been detected in NZ and have the potential to bloom and harm marine life in the future are also discussed. The use of environmental DNA (eDNA) and relevant bioassays are practical tools which enable early detection of novel, problem HAB species and rapid toxin/HAB screening, and new data from HAB monitoring of aquaculture production sites using eDNA are presented. As aquaculture grows to supply a sizable proportion of the world’s protein, the effects of HABs in reducing productivity is of increasing significance. Research into the multiple stressor effects of climate change and HABs on cultured species and using local, recent, HAB strains is needed to accurately assess effects and inform stock management strategies.

The Effects of the Harmful Algal Bloom Species Karenia brevis on Survival of Red Porgy (Pagrus pagrus) Larvae

“…The later study also failed to detect active ROS in spent media of K. brevis cultures. Recent surveys, while documenting the importance of ROS toxicity in K. mikimotoi , did not identify ROS as a major mechanism by which K. brevis causes toxicity [ 56 , 59 ]. Cumulatively, these data indicate the ROS is unlikely to account for the elevated larval mortality observed with increasing K. brevis concentrations.…”

Algae as an alternative source of protein in poultry diets for sustainable production and disease resistance: present status and future considerations

“…For instance, diatoms that produce domoic acid can cause neurological disorders and fatalities in marine wildlife, which, if transferred through the food chain, pose a threat to terrestrial livestock and poultry. Similarly, dinoflagellates responsible for red tides produce neurotoxins that can contaminate fish and shellfish ( 20 ), potentially affecting animals and humans that consume these affected resources. The implications of such toxic algae blooms are far-reaching, affecting not only the direct health of livestock and poultry but also the safety of food supplies and the broader agricultural economy.…”

Sources, Migration, Transformation, and Environmental Effects of Organic Carbon in Eutrophic Lakes: A Critical Review

“…With the elevated input of algal debris as blooms die, and the algal-derived OC can undergo degradation or heterotrophic utilization, or be transferred, accumulated, or exported (Figure 3). Algae decay consumes oxygen and releases algal toxins, which can cause the death of aquatic organisms due to hypoxia or ingestion of excess toxic substances [64,65]. When fish, shellfish, and other aquatic organisms die, their remains will also become an internal source of organic carbon.…”