Ecosystem Targets and Supporting Indicators

Invertebrate Biomass Index

Invertebrate biomass is an indicator of the productivity of the Long Island Sound.

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Invertebrate Biomass Index
Year	Invertebrate Biomass (kg/tow)
1992	16.6
1993	16.3
1994	11.3
1995	10.2
1996	15.0
1997	13.4
1998	18.2
1999	15.1
2000	13.2
2001	12.0
2002	10.8
2003	11.9
2004	10.1
2005	6.8
2006	5.1
2007	7.9
2008	6.9
2009	7.5
2010	4.8
2011	5.8
2012	4.0
2013	4.3
2014	4.4
2015	4.8
2016	4.0
2017	4.6
2018	4.7
2019	3.7
2020	N\A
2021	7.2
2022	6.3
2023	5.4

What is invertebrate biomass Index?

The Invertebrate Biomass Index is the annual average weight in kilograms of 15 invertebrate species collected in the Long Island Sound Trawl Survey. These species include various crab species (blue crab, flat claw hermit crab, horseshoe crab, lady crab, rock crab, and spider crab), American lobster, Lion’s Mane jellyfish, starfish, mantis shrimp, long-finned squid, gastropods (whelks and northern moon shells), and bivalves (blue mussel and common oyster).

What does invertebrate biomass indicate?

The invertebrate biomass index indicates the productivity of the forage base of the food chain. Many game fish species, which are both recreationally and commercial valuable, depend on the success of invertebrate species as they are important food sources. Invertebrate species Like the finfish biomass, the high invertebrate biomass also indicates good health conditions of the Sound.

Status

The Invertebrate Biomass Index shows a decreasing trend over the past 27 years. Although the American lobster makes up a large component of the invertebrate index early in the time series, analysis show a pronounced decline in many other invertebrate species over the same time series as well – such as spider, rock and lady crab species.