Does beach seine fishery permanently alter macroinvertebrate communities and sediment characteristics in the Southern Caspian Sea?

Abstract

The impacts of a beach seine fishery on macroinvertebrate communities and sediment characteristics were investigated in the Southwest Caspian Sea. Samples from a single impacted site that was regularly seined were compared with two control sites outside the fishing area. Benthic macroinvertebrates were sampled on four occasions: 6 months prior to the opening of the beach seine fishery (Time 1), 1 day immediately after the closing of beach seining (Time 2), 1 week after closing (Time 3), and 1 month after closing (Time 4). No significant differences were detected in total density, Shannon diversity, or evenness of the macroinvertebrate assemblages between impact and control sites. Unlike density, species richness increased significantly immediately after fishery closure at all sites. A significant difference was detected in the number of species between Time 2 and Time 3 at all sites and the number of species was reduced at Time 4 in all sites. Pontogammarids increased by twofold in the impact site 1 day immediately after closing beach seine fishery and leveled off toward the end of the closed season. The amplified density of pontogammarids 1 day after fishery closing at the impact site might be driven in part by an increase in sediment oxygen content resulting from disturbance of the sea floor. An alternative explanation is that the effect of fish predation on pontogammarids has largely been minimized at the impact site after 6 months of continuous fishing activity. No significant changes in the sedimentary organic content and chlorophyll-a between the impact and control sites were observed during the courses of sampling; however, a significant change occurred between the average sedimentary pheopigment content of the control sites and that of the impact site. The conclusion from the present study is that beach seine fishery does not harm to benthic communities. The closed season also seemed to allow recovery to pre-season levels of macroinvertebrate richness and sedimentary chlorophyll-a.

Before and after closed season for beach seine fishing in Ghana: Impact on benthic macroinvertebrates species diversity indices

“…These findings align with Nemati et al. (2014) who investigated the impacts of a beach seine fishery on macroinvertebrate communities and sediment characteristics in the Southwest Caspian Sea. They reported that closed season seemed to allow recovery to pre‐closing levels of macroinvertebrate richness.…”

“…ate statistics) used in the current study have all shown that closed season for beach seine fishing at both study beaches did not only improve species numbers but also richness. These findings align withNemati et al (2014) who investigated the impacts of a beach seine fishery on macroinvertebrate communities and sediment characteristics in the Southwest Caspian Sea. They reported that closed season seemed to allow recovery to pre-closing levels of macroinvertebrate richness.…”